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1
Wang, Yong, and William J. Thomson. "Mullite formation from nonstoichiometric slow hydrolyzed single phase gels." Journal of Materials Research 10, no. 4 (April 1995): 912–17. http://dx.doi.org/10.1557/jmr.1995.0912.
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A comparative dynamic x-ray diffraction (DXRD) and differential thermal analysis (DTA) study was performed in the investigation of mullite and spinel formation from slowly hydrolyzed single phase gels with Al/Si ratios ranging from 1/1 to 14/1. Both metastable tetragonal mullite and spinel were observed to form at temperatures <1000 °C in the gels with Al/Si ratios <8/1 and mullite transformed to the orthorhombic structure at ∼1250 °C. However, at higher Al/Si ratios, spinel was the only crystalline phase detected at <1000 °C and orthorhombic mullite formed directly at temperatures >1250 °C. As the Al/Si ratio increases, both the tetragonal mullite and spinel formation temperatures decrease while the orthorhombic mullite formation temperature increases. Based on the Al/Si composition where the formation extents of tetragonal mullite and spinel were maximum, their compositions are estimated to be 2Al2O3 · SiO2 and 6A12O3 · SiO2, respectively.
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Chakraborty, Akshoy kr, and Sukhen Das. "Al–Si spinel phase formation in diphasic mullite gels." Ceramics International 29, no. 1 (January 2003): 27–33. http://dx.doi.org/10.1016/s0272-8842(02)00084-6.
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Chakravorty, A. K. "Intermediate Si-Al spinel phase formation in phase transformation of diphasic mullite gel." Journal of Materials Science 28, no. 14 (January 1, 1993): 3839–44. http://dx.doi.org/10.1007/bf00353188.
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Ptáček, Petr, František Šoukal, Tomáš Opravil, Magdaléna Nosková, Jaromír Havlica, and Jiří Brandštetr. "The kinetics of Al–Si spinel phase crystallization from calcined kaolin." Journal of Solid State Chemistry 183, no. 11 (November 2010): 2565–69. http://dx.doi.org/10.1016/j.jssc.2010.08.030.
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Chakraborty, Akshoy Kr. "Reinvestigation of Al-Si Spinel Phase in Diphasic Al2O3-SiO2 Gel." Journal of the American Ceramic Society 88, no. 1 (December 29, 2004): 134–40. http://dx.doi.org/10.1111/j.1551-2916.2004.00018.x.
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Kurajica, Stanislav, Emilija Tkalčec, Vilko Mandić, Iva Lozić, and Jörg Schmauch. "Sol-Gel Derived Mullite-Gahnite Composite." Advances in Science and Technology 87 (October 2014): 126–31. http://dx.doi.org/10.4028/www.scientific.net/ast.87.126.
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Mullite-gahnite composites with different phase-proportions were prepared using sol-gel process. Crystallization path was determined using differential thermal analysis (DTA). X-ray powder diffraction (XRD) was used to study the crystal phases development. The course of the thermal reactions is dominated by the intermediate formation of two spinel phases. The former phase was attributed to gahnite, while the latter to Al-Si spinel. Zn loading decreases amounts of mullite and α-alumina, while increases gahnite and amorphous phase. The observed microstructure of sintered bodies is characterized by fine gahnite particles distributed among larger mullite grains, which is highly favourable for ceramics with high mechanical requirements.
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Sagan, P., M. Frugynskyi, R. Mroczka, and G. Wisz. "Properties of multicomponent (Mn-Ni-Co-Al-Si-Ti) oxide spinel hierarchically organized nanostructures deposited by magnetron sputtering in two temperatures." Physics and Chemistry of Solid State 22, no. 3 (September 7, 2021): 494–500. http://dx.doi.org/10.15330/pcss.22.3.494-500.
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Multicomponent spinel films were deposited on Ag/Si substrates by magnetron sputtering. Two substrate temperatures were used. XRD diffraction measurements show that the layers are composed of three metals oxides (Mn2O3, NiO, CoO). The presence of spinel phase is poorly visible. However, electron diffraction measurements (RHEED) clearly confirmed the presence of nanostructured spinel structure on top of the samples. Moreover, AFM measurements show that nanostructured spinel islands are present on the sample surface. The measurements validated that indeed, hierarchically organized spinel-oxides nanostructures were obtained. A possible model growth of the spinel nanostructures at different temperatures is discussed.
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Yokoyama, Takushi, Keisuki Nishu, Shunsuke Torii, Yoshio Ikeda, and Tokuko Watanabe. "Mullite Precursor Part I. Characterization of Mullite Precursor Formed by a Reaction of Monosilicic Acid on Aluminum Hydroxide." Journal of Materials Research 12, no. 8 (August 1997): 2111–16. http://dx.doi.org/10.1557/jmr.1997.0283.
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By adsorption of monosilicic acid on aluminum hydroxide, an amorphous aluminosilicate (AAS) of Si/Al ratio of 1/3 was formed. When the AAS was heated to 1000 °C, mullite (3Al2O3 · 2SiO2) crystallized directly without the formation of a spinel phase. It was clearly evidenced that correct adjustment of three factors, the Si/Al ratio, the proportion of 4- and 6-coordinated aluminums, and the single environment of a unit (no Si–O–Si bond), is important for the direct mullitization from AAS.
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Bosenick, A., M. T. Dove, E. R. Myers, E. J. Palin, C. I. Sainz-Diaz, B. S. Guiton, M. C. Warren, M. S. Craig, and S. A. T. Redfern. "Computational methods for the study of energies of cation distributions: applications to cation-ordering phase transitions and solid solutions." Mineralogical Magazine 65, no. 2 (April 2001): 193–219. http://dx.doi.org/10.1180/002646101550226.
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AbstractThe structural and thermodynamic properties of minerals are strongly affected by cation site-ordering processes. We describe methods to determine the main interatomic interactions that drive the ordering process, which are based on parameterizing model Hamiltonians using empirical interatomic potentials and/or ab initio quantum mechanics methods. The methods are illustrated by a number of case study examples, including Al/Si ordering in aluminosilicates, Mg/Ca ordering in garnets, simultaneous Al/Si and Mg/Al ordering in pyroxenes, micas and amphiboles, and Mg/Al non-convergent ordering in spinel using only quantum mechanical methods.
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Zhu, Chun Xiao, and Shao Feng Zhu. "Preparation of Al2O3-SiO2 Composite Powder by Sol–Gel Method." Advanced Materials Research 1053 (October 2014): 173–76. http://dx.doi.org/10.4028/www.scientific.net/amr.1053.173.
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Al2O3-SiO2 composite powder was prepared by sol-gel method, using TEOS and AlNO3 as the main raw material .XRD, SEM and the specific surface analyzer were used to characterize the powder. The results showed that powder obtained by calcining xerogel of the molar ratio of SiO2/Al2O3=1:1.5 at 1200°C had high crystallinity and purity , homogeneous distribution and small particle size that was 100-200nm. Its specific surface area decreased with the increase of the calcining temperature. The main phase of xerogel was amorphous silica. After xerogel was calcined at 400°C, 600°C and 800°C respectively, the phase of obtained powder was also amorphous silica. But at 1000°C and 1100°C respectively, small amounts of Al-Si spinel were produced. At 1200°C, the powder was all mullite and Al-Si spinel did not exist completely.
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Bae, Chul-Hong, Seong-Ho Ha, Bong-Hwan Kim, Young-Ok Yoon, Hyun-Kyu Lim, Shae K. Kim, and Young-Jig Kim. "Correlation of Surface Oxidation and Mg-Based Intermetallic Phases in Grain Boundaries of Al–Mg Alloys Containing Third Elements." Journal of Nanoscience and Nanotechnology 21, no. 3 (March 1, 2021): 2055–58. http://dx.doi.org/10.1166/jnn.2021.18948.
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In this study, the correlation of surface oxidation and Mg-based intermetallic phases in the grain boundary in Al–Mg alloys containing third elements was investigated. The experimental results were examined by phase diagrams plotted as a function of oxygen partial pressure determined by thermodynamic calculation. The addition of Si and Cu as third elements into the Al–7 mass%Mg alloy formed Mg-based secondary phases during solidification. The 1 mass% Cu addition formed three different types of Mg-based intermetallic compounds. From weight gains by oxidation, all samples exhibited their weight gains depending on time. The Si-added alloy showed a considerably lower weight gain and maintained a nearly constant weight, while the weight gain of the Al–7 mass%Mg–1 mass%Cu alloy was significantly greater than those of other alloys. MgO and MgAl2O4− spinel were the main oxides that formed the oxide scale in all examined alloys. Si addition formed the multi-element oxide including Mg and Si.
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Naghizadeh, Rahim, Hamid Reza Rezaie, and F. Golestani Fard. "Effect of Antioxidants and Atmosphere on the Phase Formation and Microstructure of In Situ MgO-Al2O3 Spinels." Defect and Diffusion Forum 273-276 (February 2008): 542–48. http://dx.doi.org/10.4028/www.scientific.net/ddf.273-276.542.
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The formation of in-situ spinel in Al2O3-MgO-C refractories along with different antioxidants occurs at different atmospheres in surface and inner of refractories. Then the types and microstructures of established phases have become increasingly important in these refractories. In the present work, reactions on firing Al2O3-MgO samples with added graphite, Al, Si and SiC in air or coke bed atmosphere at 1300°C and 1600°C have been studied. The results showed that with the addition of graphite and Al especially at 1600°C in coke bed, high alumina-rich spinel (Mg0.866Al1.83O3.611) was increased and in the microstructure were appeared high amount porosity. In silicon and silicon carbide additive samples after firing at 1600°C in coke bed, sapphirine phase were revealed.
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SHAW, CLIFF S. J., and ALAN D. EDGAR. "Post-entrainment mineral–melt reactions in spinel peridotite xenoliths from Inver, Donegal, Ireland." Geological Magazine 134, no. 6 (November 1997): 771–79. http://dx.doi.org/10.1017/s001675689700784x.
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Spinel lherzolite and harzburgite xenoliths hosted in an alkali basalt dyke near Inver, Donegal, Ireland show abundant evidence of interaction between xenolith minerals and the host melt. Of particular interest are primary Cr-diopside and spinel with sieve-textured coronas. Coronas on primary Cr-diopside are up to 3 mm wide and are associated with veinlets of devitrified glass. The coronas comprise secondary Cr-diopside with vermicular, interstitial alkali feldspar and chlorite grains up to 100 µm in size. The inclusion-free Cr-diopside cores are Al- and Na-rich whereas the coronas are Al- and Na-depleted and Ti-enriched. Sieve-textured spinels have similar texture to the clinopyroxene grains and are also associated with veinlets of infiltrated glass. However, the interstitial inclusions in the sieve-textured region are chlorite and nepheline. Inclusion-free spinel is part of a chromite–spinel solid solution and is Ti-poor. Spinel in the coronas has a greater chromite and ulvospinel component and falls close to a mixing line with spinel in the host alkali basalt. In addition to the sieve-textured grains, primary olivine in contact with infiltrated glass has Fe-rich rims, and orthopyroxene has broken down to form rims of olivine, clinopyroxene and a K-rich phase similar in composition to alkali-feldspar. Comparison of the compositions of the inclusion-free cores and sieve-textured rims shows that the rims have chemical signatures consistent with partial melting, that is, Al and Na depletion for clinopyroxene and Cr-enrichment for spinel. The textures of the coronas, particularly those around spinel and the reaction margins on orthopyroxene are identical to those produced during dissolution experiments.We suggest that silicate liquid from the host magma infiltrated the xenoliths during their ascent and since it was not in equilibrium with the xenolith minerals caused reaction. The occurrence of K-bearing interstitial minerals in the sieve-textured grains and reacted orthopyroxenes indicate that the coronas did not form by simple melting since none of the minerals that underwent breakdown are K-bearing. We suggest that the sieve-textured grains formed initially by partial melting and reaction associated with decompression and infiltration of liquid from the host magma. The melts included in the reacted phases were enriched in K by diffusion from the Si-poor infiltrated melt into the more Si-rich melt inclusions in the coronas.
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Temuujin, J., K. Okada, and K. J. D. MacKenzie. "Characterization of aluminosilicate (mullite) precursors prepared by a mechanochemical process." Journal of Materials Research 13, no. 8 (August 1998): 2184–89. http://dx.doi.org/10.1557/jmr.1998.0305.
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Aluminosilicate precursors were prepared by mechanochemical treatment of gibbsitesilica gel mixtures. The effect of grinding on their structure and thermal behavior has been examined by 27Al and 29Si MAS NMR, x-ray diffraction (XRD), differential thermal analysis-thermogravimetry (DTA-TG), and Fourier transform infrared (FTIR). After 8 h grinding, the hydrated alumina was completely changed to an amorphous phase which showed a new exothermic DTA peak at about 980 °C due to the formation of γ–Al2O3 or spinel phase. This behavior was related to changes in the Al and Si environments, as deduced from the MAS NMR spectra. With increased grinding time, some 4-coordinated Al appears, together with an Al resonance at about 30 ppm. Simultaneously, a new Si resonance appears at about −90 ppm, indicating a greater degree of homogeneity in the ground samples. Mullite crystallizes at 1200 °C from samples ground for 8–20 h, its XRD intensity increasing with increased milling times, in agreement with the NMR, DTA, and FTIR data. Changes in the Al and Si environments during heat treatment, as reflected by the NMR spectra, are also reported.
15
Li, Dong X., and William J. Thomson. "Tetragonal to orthorhombic transformation during mullite formation." Journal of Materials Research 6, no. 4 (April 1991): 819–24. http://dx.doi.org/10.1557/jmr.1991.0819.
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The mullite formation process in both single phase and diphasic sol-gel precursors to mullite was studied using dynamic x-ray diffraction (DXRD). A metastable, tetragonal-like mullite phase was observed in all the single gels at temperatures from 980 °C to 1200 °C, but not in any of the other precursors. The tetragonal to orthorhombic mullite transformation was very slow as the lattice parameters, a and b, split and moved gradually away from each other as a result of a gradual decrease of alumina content in the mullite solid solution with increasing temperature from 1100 °C to 1200 °C. The formation of tetragonal mullite coincides with that of the Al–Si spinel. The occurrence of tetragonal mullite or the spinel (or both) is determined mainly by the processing conditions of the sol-gel precursors.
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Gorbachev, N. S., A. V. Kostyuk, Yu B. Shapovalov, P. N. Gorbachev, A. N. Nekrasov, and D. M. Soultanov. "Phase relations at interaction of phlogopite with carbonate melt at Р = 3.8 GPa." Доклады Академии наук 488, no. 6 (October 30, 2019): 640–44. http://dx.doi.org/10.31857/s0869-56524886640-644.
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The phase relations in the phlogopite-carbonate system were studied at P = 3.8 GPa, T = 1200-1300 C. The interaction of phlogopite with carbonate melt resulted in the formation of a polymineral association of relic and newly formed phases of the phlogopite-carbonate-clinopyroxene-spinel-garnet composition coexisting with carbonate melt. By increasing the temperature from 1200 to 1300 C in the carbonate melt increases the solubility of phlogopite and the concentrations of its components - Si, Al, Mg, K. The phase composition of the quenching phases of the carbonate melt varies from substantially carbonate with isolated microcrystals of apatite and phlogopite at 1200 C to phlogopite-carbonate with a variety of texture ratios at 1300 C, reflecting the spontaneous crystallization of the carbonate melt during quenching. In the studied P-T, close to the mantle adiabate, phlogopite remains stable in the presence of silicate-carbonate melt.
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LIANG, SEN, XIAO ZHANG, HAIBO LI, MIN LUO, JIN LI, LIJUN HE, and JIANFENG YANG. "FABRICATION AND CHARACTERIZATION OF Ni–Mn–Si–Al–O NTC THERMISTOR AND ITS APPLICATION AS TEMPERATURE WIRE SENSOR." Functional Materials Letters 06, no. 04 (August 2013): 1350039. http://dx.doi.org/10.1142/s1793604713500392.
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A series of Al 2 O 3 substituted manganese oxide ceramic compounds, Ni 0.6 Si 0.2 Mn 2.2-x Al x O 4(0 ≤ x ≤ 0.6), were prepared by solid-state reaction route. The phase composition, microstructure, and electrical properties of compounds were studied. The results revealed that all the compounds were composed of cubic spinel structure without any other oxides. Besides they exhibited a linear relationship between logarithm of electrical resistivity (ln ρ) and reciprocal of absolute temperature (1/T) over a temperature ranging from room temperature to 300°C, which indicated a negative temperature coefficient (NTC) characteristic. The B25/85 constant was found to increase with the increase of Al 2 O 3 content. The B25/85 values of the NTC Ni 0.6 Si 0.2 Mn 2.2-x Al x O 4 thermistors for x = 0,0.1,0.2,0.3,0.4, and 0.6 were 4581, 4612, 4680, 4875, and 5089 K, respectively. Finally, a new method to produce one meter long continuous fire wire sensors was also proposed.
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Matrosova, E. А., А. А. Bendeliani, A. V. Bobrov, A. A. Kargal’tsev, and Yu A. Ignat’ev. "Phase relations in the model pyrolite at 2.5, 3.0, 7.0 GPа and 1400–1800°c: evidence for the formation of high-chromium garnets." Геохимия 64, no. 9 (September 20, 2019): 974–85. http://dx.doi.org/10.31857/s0016-7525649974-985.
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Based on study of partial melting in the model pyrolite, it is shown that garnets synthesized at 7.0 GPa in a temperature range of 1400–1800°C are characterized by an excessive Si content (in relation to 3 f.u.), stable admixture of Cr2O3, and, thus, represent a solid solution of the pyrope–majorite–knorringite composition. Increase in the Cr/Al value in the starting composition results in increase of this ratio in garnet. With increasing temperature, the concentration of Cr2O3 decreases in restite and increases in melt. Cr/Al increases in all garnets from the zone of restite and from the quenched melt aggregate. Estimates of the bulk compositions of restite formed by partial melting of the model pyrolite at 2.5 and 3.0 GPa show that the concentration of Cr in it is higher than that in the starting composition. All minerals from the zone of restite are characterized by the high Cr concentrations, and upon partial melting in the spinel-depth facies, Cr is redistributed to restite. Our results show that the formation of high-chromium garnets relates to the protolith with the high Cr/Al value formed as a residue from partial melting in the spinel-depth facies and further transported to the garnet facies.
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Tong, Lin Xin, Jin Hong Li, and Jian Cao. "Synthesis and Characterization of Ti, Fe-Doped Mullite-I." Advanced Materials Research 217-218 (March 2011): 163–68. http://dx.doi.org/10.4028/www.scientific.net/amr.217-218.163.
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A series of gels with 3Al2O3•2SiO2 were prepared by Sol-gel method and heated at several temperatures for 2 h to synthesize Ti, Fe-doped mullite. The powers were characterized by differential thermal analysis (DSC-TG) and X-ray powder diffraction (XRD). Phase separation was promoted by doping both TiO2 and Fe2O3; with increasing the amount of dopant ions the formation temperature of Si-Al spinel decreased and the formation temperature of mullite increased by TiO2 doping but decreased by Fe2O3 doping. The formation temperature of pure mullite was about 1250-1350 °C.
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Janaćković, Dj, V. Jokanović, Lj Kostić-Gvozdenović, Lj Živković, and D. Uskoković. "Synthesis, morphology, and formation mechanism of mullite particles produced by ultrasonic spray pyrolysis." Journal of Materials Research 11, no. 7 (July 1996): 1706–16. http://dx.doi.org/10.1557/jmr.1996.0214.
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Submicrometer spherical particles of mullite powder were synthesized by ultrasonic spray pyrolysis of emulsion and solutions, using tetra-ethyl-orthosilicate (TEOS) or silicic-acid and Al(NO3)3 · 9H2O as initial compounds. Crystallization of mullite phase was determined by differential thermal (DT), thermogravimetric (TG), infrared (IR), and x-ray analyses. The synthesis of mullite from TEOS emulsion occurs by crystallization of γ–Al2O3 (or Al, Si-spinel) from the amorphous phase and its subsequent reaction with amorphous SiO2, as well as by crystallization of pseudotetragonal mullite below 1000 °C and its subsequent phase transformation into orthorhombic mullite. In the powders produced from silicic acid solutions, synthesis of mullite occurs only by crystallization of γ–Al2O3 between 900 and 1000 °C and its further reaction with amorphous SiO2 between 1100 and 1200 °C. Particle formation mechanism depended directly on the initial emulsion or solution preparation, i.e., on the phase separation in the emulsion and on the silicic-acid crosslinking conditions.
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Zhuang, Ying, Zhou Hua Jiang, and Yang Li. "Thermodynamics Software Development on Composition Prediction of Inclusions in Molten 430 Stainless Steel." Advanced Materials Research 430-432 (January 2012): 337–40. http://dx.doi.org/10.4028/www.scientific.net/amr.430-432.337.
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Thermodynamics software on inclusions prediction in 430 stainless steel was developed with Matlab and VC++. The inclusions’ composition could be predicted by composition of molten steel input, and equilibrium phase diagrams of MgO•Al2O3, 2MgO•SiO2, 3Al2O3•2SiO2 and 2Al2O3•2MgO•5SiO2 were displayed on the main interface simultaneously. The following predicted results by inputing experiments data at 1873 K can be gained that When Si content is 3.9×10-3and Al content is 3.5×10-4, MgO•Al2O3 spinel inclusions is unformed in case of Mg content with larger than 1.71×10-5; while MgO•Al2O3 spinel inclusions transformed into 2Al2O3•2MgO•5SiO2 inclusions in case of Mg content being less than 2.9×10-8. The predicted results of software fit well with the experiment results, Therefore, the software can provide some results for controlling the composition of inclusions in molten steel.
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Leivo, Jarkko, Mika Lindén, Cilâine V. Teixeira, Janne Puputti, Jessica Rosenholm, Erkki Levänen, and Tapio A. Mäntylä. "Sol-gel synthesis of a nanoparticulate aluminosilicate precursor for homogeneous mullite ceramics." Journal of Materials Research 21, no. 5 (May 1, 2006): 1279–85. http://dx.doi.org/10.1557/jmr.2006.0152.
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An amorphous nanoparticulate aluminosilicate 3/2-mullite precursor has been synthesized and carefully characterized. The sol contained 2-nm particles of Q3(3Al) silica species together with six-coordinated alumina, which suggested an allophane-like structure of the nanoparticles. The sol remained stable for years, and formed an easily redispersible physical gel upon solvent evaporation. The gel crystallized to mullite at temperatures below 1000 °C, without going through any intermediate spinel phase. Thus, the nanoparticulate precursor is regarded as a homogeneous high-purity mullite precursor with a high Si–O–Al bond density, which is useful in the preparation of various nanostructured Al-rich aluminosilicate materials. The sols and gels were characterized by small-angle x-ray scattering, dynamic light scattering, x-ray diffraction, 27Al and 29Si magic-angle spinning (MAS) nuclear magnetic resonance spectroscopy, and differential thermal analysis.
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Erasmus, Elizabeth. "The influence of thermal treatment on properties of kaolin." Chemical Industry 70, no. 5 (2016): 595–601. http://dx.doi.org/10.2298/hemind150720066e.
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The kinetics of dehydroxylation of South African kaolin revealed that both the inner and the surface hydroxyl groups disappear according to first order kinetics, however, the surface group disappeared faster than the inner groups, showing that diffusion control kinetics is also important. The temperature dependent transformations of the kaolin was measure by means of fractional conversion of the ratios between AlO6:AlO4 and Si-O-Al:Si-O-Si, which showed kobs values 0.0168 s-1 and 0.0089 s-1 for the transformation to the spinel phase and values of 0.0165 s-1 and 0.0156 s-1 for the transformation to mullite respectively. The pozzolanic activities of the kaolin calcined at different temperatures showed a maximum pozzolanic activity when the kaolin is calcined at 650?C and the pozzolanic activity for mullite is even less than for the uncalcined kaolin. XPS revealed that the atomic ratio between Si and Al did not change from kaolin to metakaolin (Si:Al = ca. 1.2) however the mullite showed a atomic ratio of Si:Al = 1.52, implying that some deallumination occurred during calcination at high temperatures.
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Iaiche, Sabrina, Chahra Boukaous, David Alamarguy, Abdelkader Djelloul, and Djamel Hamana. "Effect of Solution Concentration on ZnO/ZnAl2O4 Nanocomposite Thin Films Formation Deposited by Ultrasonic Spray Pyrolysis on Glass and Si(111) Substrates." Journal of Nano Research 63 (June 2020): 10–30. http://dx.doi.org/10.4028/www.scientific.net/jnanor.63.10.
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A complex ZnO/ZnAl2O4 heterostructures thin films on glass and Si (111) substrates have been successively obtained by a soft ultrasonic spray pyrolysis (USP) method deposition using the Zn/Al molar ratios concentrations of 0.07/0.13 and 0.1/0.1, respectively. According to (XRD) an ordered zinc oxide (ZnO) and zinc aluminate (ZnAl2O4) structures deposited onto glass from the air annealing at 500 °C during 2 hours was observed and confirmed by the (EDX), (FTIR) and Raman spectroscopy techniques. The estimated crystallites size and stress values of ZnO and ZnAl2O4 in the ZnO/ZnAl2O4/glass film were 19 nm/0.469 GPa and 11 nm/-0.292 GPa, respectively. The lower Zn/Al molar ratio around 0.035/0.06 produced only ZnO as a single phase, suggesting the Al insufficient quantity. The Si (100) substrate with 0.07 Zn molarity conducted to the Zn2SiO4/ZnO/ZnAl2O4 composite. The Raman integrated intensity bands of ZnO and ZnAl2O4 increases with increasing Zn to Al molar ratio (0.1/0.1 comparatively to 0.07/0.13). The ZnO&ZnAl2O4 crystallinity enhances as Zn molarity increases. The ZnO films in the composites grow with (002) texture. The TC(hkl) value indicated that ZnAl2O4 in the ZnO/ZnAl2O4/glass layer is polycrystalline preferentially oriented along the (311) plane. Spinel ZnAl2O4 oxide onto Si (111) substrate grown according to the (220) orientation. Crystallites are larger in ZnO/ZnAl2O4/Si than in ZnO/ZnAl2O4/glass. The ZnO/ZnAl2O4 film onto glass substrate is transparent in the visible and near infrared regions and sensitive to UV absorption, as characterized by UV-Vis spectroscopy. The ZnO and ZnAl2O4Egvalues in the ZnO/ZnAl2O4/glass composite were 3.25 and 3.88 eV, respectively.
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Zhan, Zhonghua, Weifeng Zhang, Yanling Zhang, Ruxing Shi, and Guoguang Cheng. "Formation and Evolution of DS-Type Inclusions in 15-5PH Stainless Steel." Metals 11, no. 7 (July 16, 2021): 1129. http://dx.doi.org/10.3390/met11071129.
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15-5PH stainless steel castings are key components in fracturing trucks. However, DS-type inclusions can lead to fatigue failure of the material. To elucidate the formation mechanism of large-size DS-type inclusions, the evolution, growth, and aggregation of inclusions during vacuum oxygen decarburization, ladle refining, and vacuum casting were studied. The results show that the DS-type inclusions with sizes larger than 20 μm were CaO–Al2O3–SiO2–MgO–CaS composite inclusions. After Si–Al additions in vacuum degassing, typical inclusions were spinel or Al2O3. After Ca–Si additions during ladle treatment, typical inclusions were liquid or dual-phase Al2O3–CaO–SiO2–MgO. During the solidification process, due to the segregation of S and the decrease in solubility, the typical inclusions in the final casting became Al2O3–CaO–SiO2–MgO–CaS. For optimal fatigue performance of stainless steel castings, slag and refractory composition control were also necessary because the [Mg] contents mainly come from the slag and lining.
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Xing, Xiangdong, Zhuogang Pang, Jianlu Zheng, Yueli Du, Shan Ren, and Jiantao Ju. "Effect of MgO and K2O on High-Al Silicon–Manganese Alloy Slag Viscosity and Structure." Minerals 10, no. 9 (September 14, 2020): 810. http://dx.doi.org/10.3390/min10090810.
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The viscosity, melting proprieties, and molten structure of the high-Al silicon–manganese slag of SiO2–CaO–25 mass% Al2O3–MgO–MnO–K2O system with a varying MgO and K2O content were studied. The results show that with the increase in MgO content from 4 to 10 mass%, the measured viscosity and flow activation energy decreases, but K2O has an effect on increasing those of slags. However, the melting temperature increases due to the formation of high-melting-point phase spinel. Meanwhile, Fourier transform infrared (FTIR) and X-ray photoelectron spectra (XPS) were conducted to understand the variation of slag structure. The O2− dissociates from MgO can interact with the O0 within Si–O or Al–O network structures, corresponding to the decrease in the trough depth of [SiO4] tetrahedral and [AlO4] tetrahedral. However, when K2O is added into the molten slag, the K+ can accelerate the formation of [AlO4] tetrahedra, resulting in the increase in O0 and O− and the polymerization of the structure.
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Ondruška, Ján, Igor Štubňa, Viera Trnovcová, Tomáš Húlan, and Libor Vozár. "DC Conductivity of Illite with Fly-Ash between 20 – 1050 °C." Advanced Materials Research 1126 (October 2015): 123–28. http://dx.doi.org/10.4028/www.scientific.net/amr.1126.123.
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The temperature dependence of the electrical DC conductivity of fly-ash and illite-based ceramics was measured in the temperature range of 20 – 1050 °C. The measurements were done for illite samples with no fly-ash and fired illite added and illite samples containing 10 wt. %, 20 wt. %, 30 wt. %, and 40 wt. % of fly-ash and 0 wt. %, 10 wt. %, 20 wt. %, and 30 wt. % of fired illite. Addition of fly-ash substantially influences temperature dependences of the DC conductivity and introduces a temperature region with a high conduction activation energy which precedes the dehydroxylation. At the lowest temperatures, the main charge carriers are H+ and OH− ions, while at higher temperatures K+ and Na+ ions also play a role. The phase transformation metaillite -> Al-Si spinel is characterized with a current peak at 940 °C.
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Zhang, Tongsheng, Rensheng Li, Wanlin Wang, Shifan Dai, Peisheng Lv, and Yan Tian. "Research on the variation of the inclusion and sulfur content in Pipeline steel." Metallurgical Research & Technology 118, no. 2 (2021): 214. http://dx.doi.org/10.1051/metal/2021010.
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Pipeline steel is widely used in various industries, and the sulfur content and inclusions in steel have a significant impact on performance, which determines whether the steel quality is qualified. The experiments were carried out to explore the sulfur content and inclusion evolution of pipeline steel which was deoxidized by Si–Mn–Al with “EAF-LF-VD-T-CC”. The samples of molten steel and slag were taken during the process of LF-VD-Tundish after EAF tapping. The kinetics model was established to simulate the desulfuration process of molten steel in actual production, obtaining a result which the error is within 3 ppm. It can be summarized that proper calcium treatment can transform the inclusion into a liquid inclusion, the value of [Ca] ranges from 25 to 45 ppm. Too high and lower calcium treatment can cause the compositions of inclusions to deviate from the liquid phase area, while too low calcium treatment will increase the overall size and density of the inclusions. In addition, the evolution of inclusion in steel at refining temperature and during solidification process was comprehensively calculated, considering all types of inclusions such as calcium oxide, magnesium oxide, aluminum oxide, calcium sulfide, spinel, calcium aluminate and liquid inclusion. The thermodynamic calculations are in good agreement with experimental results, which can predict the formation of the inclusions in Si–Mn–Al deoxidized pipeline steel.
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Hensen, B. J. "Theoretical phase relations involving cordierite and garnet revisited: the influence of oxygen fugacity on the stability of sapphirine and spinel in the system Mg-Fe-Al-Si-O." Contributions to Mineralogy and Petrology 92, no. 3 (1986): 362–67. http://dx.doi.org/10.1007/bf00572165.
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Yeh, Chun-Liang, and Yin-Chien Chen. "Formation of Mo5Si3/Mo3Si–MgAl2O4 Composites via Self-Propagating High-Temperature Synthesis." Molecules 25, no. 1 (December 24, 2019): 83. http://dx.doi.org/10.3390/molecules25010083.
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In situ formation of intermetallic/ceramic composites composed of molybdenum silicides (Mo5Si3 and Mo3Si) and magnesium aluminate spinel (MgAl2O4) was conducted by combustion synthesis with reducing stages in the mode of self-propagating high-temperature synthesis (SHS). The SHS process combined intermetallic combustion between Mo and Si with metallothermic reduction of MoO3 by Al in the presence of MgO. Experimental evidence showed that combustion velocity and temperature decreased with increasing molar content of Mo5Si3 and Mo3Si, and therefore, the flammability limit determined for the reaction at Mo5Si3 or Mo3Si/MgAl2O4 = 2.0. Based upon combustion wave kinetics, the activation energies, Ea = 68.8 and 63.8 kJ/mol, were deduced for the solid-state SHS reactions producing Mo5Si3– and Mo3Si–MgAl2O4 composites, respectively. Phase conversion was almost complete after combustion, with the exception of trivial unreacted Mo existing in both composites and a minor amount of Mo3Si in the Mo5Si3–MgAl2O4 composite. Both composites display a dense morphology formed by connecting MgAl2O4 crystals, within which micro-sized molybdenum silicide grains were embedded. For equimolar Mo5Si3– and Mo3Si–MgAl2O4 composites, the hardness and fracture toughness are 14.6 GPa and 6.28 MPa m1/2, and 13.9 GPa and 5.98 MPa m1/2, respectively.
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Griffin, William, Sarah Gain, Luca Bindi, Vered Toledo, Fernando Cámara, Martin Saunders, and Suzanne O’Reilly. "Carmeltazite, ZrAl2Ti4O11, a New Mineral Trapped in Corundum from Volcanic Rocks of Mt Carmel, Northern Israel." Minerals 8, no. 12 (December 19, 2018): 601. http://dx.doi.org/10.3390/min8120601.
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The new mineral species carmeltazite, ideally ZrAl2Ti4O11, was discovered in pockets of trapped melt interstitial to, or included in, corundum xenocrysts from the Cretaceous Mt Carmel volcanics of northern Israel, associated with corundum, tistarite, anorthite, osbornite, an unnamed REE (Rare Earth Element) phase, in a Ca-Mg-Al-Si-O glass. In reflected light, carmeltazite is weakly to moderately bireflectant and weakly pleochroic from dark brown to dark green. Internal reflections are absent. Under crossed polars, the mineral is anisotropic, without characteristic rotation tints. Reflectance values for the four COM wavelengths (Rmin, Rmax (%) (λ in nm)) are: 21.8, 22.9 (471.1); 21.0, 21.6 (548.3), 19.9, 20.7 (586.6); and 18.5, 19.8 (652.3). Electron microprobe analysis (average of eight spot analyses) gave, on the basis of 11 oxygen atoms per formula unit and assuming all Ti and Sc as trivalent, the chemical formula (Ti3+3.60Al1.89Zr1.04Mg0.24Si0.13Sc0.06Ca0.05Y0.02Hf0.01)Σ=7.04O11. The simplified formula is ZrAl2Ti4O11, which requires ZrO2 24.03, Al2O3 19.88, and Ti2O3 56.09, totaling 100.00 wt %. The main diffraction lines, corresponding to multiple hkl indices, are (d in Å (relative visual intensity)): 5.04 (65), 4.09 (60), 2.961 (100), 2.885 (40), and 2.047 (60). The crystal structure study revealed carmeltazite to be orthorhombic, space group Pnma, with unit-cell parameters a = 14.0951 (9), b = 5.8123 (4), c = 10.0848 (7) Å, V = 826.2 (1) Å3, and Z = 4. The crystal structure was refined to a final R1 = 0.0216 for 1165 observed reflections with Fo > 4σ(Fo). Carmeltazite exhibits a structural arrangement similar to that observed in a defective spinel structure. The name carmeltazite derives from Mt Carmel (“CARMEL”) and from the dominant metals present in the mineral, i.e., Titanium, Aluminum and Zirconium (“TAZ”). The mineral and its name have been approved by the IMA Commission on New Minerals, Nomenclature and Classification (2018-103).
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Zulfia, Anne, Tatu Mas’udah, and Syukron Lutfi. "Electroless Deposition of Metal Oxide on SiC Particles Reinforced for Producing Al-Si /SiC Metal Matrix Composites." Advanced Materials Research 277 (July 2011): 43–50. http://dx.doi.org/10.4028/www.scientific.net/amr.277.43.
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Metallization techniques based on electroless coating are used to coat SiC particles reinforced to make Al-Si/SiC metal matrix composites. Nitric Acid (HNO3), aluminum powder and different percentage of magnesium addition were used in solutions as electroless coating medium to coat the surface of SiC particles. Five different percentage of Mg was used from 0.1 to 0.5 wt% in electrolyte solution. Metal oxide coating was characterised by scanning electron microscope (SEM), energy dispersion spectroscopy (EDS), X-ray diffraction (XRD) as well as Transmission Electron Microscope (TEM). It is obtained that metal oxide layer formed on the SiC surface was MgAl2O4or spinel which was analysed by XRD and confirmed by EDS. Spinel (MgAl2O4) layer was found at all composition of Mg, and such layer improved wettability between SiC and Al-Si. It also is found that the solution with 0.2%wt Mg content generated more homogeneous metal oxide layer on SiC particles therefore the solution with 0.2wt% Mg was selected as electroless coating medium to coat SiC particles reinforced to produce Al-Si/SiC metal matrix composites by stir casting route. The phases present in Al-Si/SiC composites was spinel (MgAl2O4), Si eutectic and Mg2Si which was analysed by XRD.
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Jaques, A. Lynton, Frank Brink, and Jiang Chen. "Magmatic haggertyite in olivine lamproites of the West Kimberley region, Western Australia." American Mineralogist 105, no. 11 (November 1, 2020): 1724–33. http://dx.doi.org/10.2138/am-2020-7456.
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Abstract We report the first occurrence of magmatic haggertyite (BaFe6Ti5MgO19) from the Miocene lamproites of the West Kimberley region of Western Australia. This contrasts with the metasomatic formation reported in an olivine lamproite host at the type locality, Prairie Creek, Arkansas. Haggertyite occurs in the groundmass of a diamondiferous olivine lamproite pipe in the Ellendale field, and within the large zoned Walgidee Hills lamproite where it forms part of an extensive suite of Ba- and K-bearing titanate and Ti-rich silicate minerals. The haggertyite co-exists with chromian spinel, perovskite, and ilmenite in the Ellendale lamproite, and with priderite and perovskite and, in one locality, with priderite, jeppeite, ilmenite, and perovskite, in the Walgidee Hills lamproite. Unlike priderite and perovskite, which are common groundmass phases in the Ellendale olivine lamproites and present throughout the Walgidee Hills lamproite, haggertyite appears restricted in its occurrence and crystallization interval, with sparse ilmenite apparently mostly crystallizing as an alternative phase. In the Walgidee Hills lamproite the haggertyite-bearing assemblage is succeeded by the Ba-titanate assemblage priderite plus jeppeite in the evolved central part of the body. The haggertyite in the main zone of the Walgidee Hills lamproite has an average composition of (Ba0.7K0.3)1.0(Ti5.0Fe2.13+Cr0.1Fe3.82+Mn0.2Mg0.6Na0.1)12O19 and is thus very similar to the original haggertyite described from xenoliths in the Prairie Creek lamproite apart from being poorer in Cr and Ni. Haggertyite in the groundmass of the Ellendale olivine lamproite and the central zone of the Walgidee Hills lamproite, in addition to variations in Mg and Cr, show significant variation in Ti and Fe contents and in calculated Fe3+ and Fe2+. A linear inverse relationship between Ti and Fe, and Ti and Fe3+, indicates that Fe3+ is accommodated by the coupled substitution Ti4+ + Fe2+ ⇆ 2 Fe3+. A marked trend to higher Fe3+ in the haggertyite in Ellendale 9 olivine lamproite is ascribed to increasing oxidation during crystallization, with fO2 estimated from the olivine-spinel thermometer and oxygen barometer at Dlog FMQ = –1 to +3 at temperatures of 790–660 °C. The haggertyite in the central zone of the Walgidee Hills lamproite, in contrast, shows a marked trend to Fe2+ enrichment, which is associated with decreasing Fe in perovskite. This is inferred to indicate formation under more reducing conditions, but sufficiently oxidized to permit Fe3+ in co-existing priderite and jeppeite. Trace-element analysis by LA-ICP-MS shows the Walgidee Hills haggertyite contains minor amounts of Na, Si, Ca, V, Co, Zn, Sr, Zr, Nb, and Pb, and only traces of Al, P, Sc, Rb, REE, Hf, and Ta. Moreover, the haggertyite is preferentially enriched in certain lithophile (Ba, Sr), siderophile (Mn, Fe, Co, Ni), and chalcophile (Zn, Pb) elements relative to co-existing priderite. Haggertyite crystallization appears to be a consequence not only of the very high Ba, Ti, and K contents of the lamproite, but of relatively high-Fe concentrations and low temperatures in evolved olivine lamproite magma with the Fe3+/Fe2+ ratio determined by the prevailing fO2. The new data suggest that haggertyite might also be present but previously unrecognized in the evolved groundmass of other olivine lamproites. Haggertyite is one of an increasing number of new minerals in upper mantle rocks and volcanics derived from the upper mantle hosting large-ion-lithophile and high field strength cations.
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Huang, Q., and X. Lv. "Phases transformation of nickel lateritic ore during dehydration." Journal of Mining and Metallurgy, Section B: Metallurgy 47, no. 1 (2011): 45–51. http://dx.doi.org/10.2298/jmmb1101045h.
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The high magnesium nickel laterite ore need first be dehydrated if it is treated by the pirometallurgical means. The nickel laterite ore was dehydrated in a laboratory scale sintering pot in this study. The dehydration mechanism was studied by using the thermo-gravimetric (TG) tests, differential thermal analysis (DTA), and X-ray diffraction (XRD) experiments. The measurements indicated that chlorite (Fe,Mg,Al)6(Si,Al)4O10(OH)8 and serpentine Mg21Si12O28(OH)34H2O are the primary phases, while FeO(OH) and (Fe,Mg,)3Si4O10(OH)2 are the minor phases in the ore. The water in the ore can be divided as free water, crystal water, and hydroxyl group. During the heating process, the temperature range for the removal of the free water is 25~140?C, for the crystal water it is 200~480 ?C, and for the hydroxyl group it is 500~800?C. The experiments with various coal dosages show that the temperatures of off-gas and burden increase with an increase in coal dosage. The sinter samples were analyzed using XRD. The results demonstrated that olivine (Mg,Fe)2SiO4 and spinel MgFe2O4 are the main bonding phases.
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Ortega-Lazcano, Jesús Benjamín, Demetrio Mendoza-Anaya, Eleazar Salinas-Rodríguez, Juan Hernández-Ávila, Otilio Arturo Acevedo-Sandoval, and Ventura Rodríguez-Lugo. "Study of Pigments from the Colonial Convent of Actopan, Hidalgo, Mexico." Minerals 11, no. 8 (August 7, 2021): 852. http://dx.doi.org/10.3390/min11080852.
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In this work, scanning electron microscopy (SEM), X-ray diffraction (XRD), and infrared spectroscopy (FTIR) techniques were used to study blue, red, and ochre pigments from wall paintings of the 16th century colonial convent of San Nicolás de Tolentino in Actopan, Hidalgo, Mexico. In the blue pigments, nanometric fibers with a chemical composition of mostly O, Si, Al, and Mg were identified. XRD and FTIR analysis indicated the presence of palygorskite clay, which suggests that these analyzed blue pigments are similar to Mayan blue. In the red pigment, structures with different morphologies (spines and flake shapes, for instance), with a composition of C, O, Al, Si, S, Ca, Na, Mg, and K and a higher concentration of Fe and Pb, were observed. Complementary analysis showed that the red color originates from hematite and lead. Finally, the ochre pigment showed a significant presence of O and Fe, which was associated with the goethite mineral, while calcite was a crystalline phase identified in all analyzed pigments; these show that these pigments are characteristic of the known Mexican Colonial color palette.
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Ahmad, Nor E., Julian R. Jones, and William E. Lee. "Durability studies of simulated UK high level waste glass." MRS Proceedings 1665 (2014): 291–96. http://dx.doi.org/10.1557/opl.2014.657.
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ABSTRACTA simulated Magnox glass which is Mg- and Al- rich was subjected to aqueous corrosion in static mode with deionised water at 90 °C for 7-28 days and assessed using X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) with Energy X-Ray Dispersive Spectroscopy (EDS) and Inductively Coupled Plasma – Optical Emission Spectroscopy (ICP-OES). XRD revealed both amorphous phase and crystals in the glass structure. The crystals were Ni and Cr rich spinels and ruthenium oxide. After two weeks of incubation in deionised water, the glass surface was covered by a ∼11 μm thick Si-rich layer whilst mobile elements and transition metals like Na, B, and Fe were strongly depleted. The likely corrosion mechanism and in particular the role of Mg and Al in the glass structure are discussed.
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Montoya-Dávila, Miguel, Max A. Pech-Canul, and Martin I. Pech-Canul. "Microstructure and Mechanical Properties of Al/Sicp Composites with Multimodal Size Distribution of Reinforcements." Materials Science Forum 560 (November 2007): 115–20. http://dx.doi.org/10.4028/www.scientific.net/msf.560.115.
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The effect of particle size distribution and particle size ratio of SiCp in SiCp/SiO2 preforms on the microstructure, microhardness of SiCp reinforcements, modulus of rupture, and superficial hardness of Al/SiCp composites produced by pressureless infiltration has been investigated. SiCp/SiO2 preforms in the form of plates (4cm x 3cm x 0.5cm) have been pressureless infiltrated by the alloy Al-15.52 Mg-13.62 Si (wt. %) at 1100 oC for 60 min under inert atmosphere. SiC powders with average particle size of 10, 68 and 140 μm are mixed with SiO2 powders and preforms of 40 % porosity with unimodal, bimodal and trimodal size distributions are prepared by uniaxial compaction. The bimodal (small: large) and trimodal (small: medium: large) preforms are prepared with different particle size ratios in the following levels: 1:1, 3:1, 1:3, 2:2:2, 3:2:1, 3:1:2. Results from characterization by XRD, SEM and energy dispersive X-ray spectrometry show that the typical microstructure of the composites contains the MgAl2O4 (spinel), AlN and MgO phases formed during processing as well as partially reacted silica, SiC, Si and Al. It is found that the density, reinforcement microhardness, modulus of rupture and superficial hardness of the composites increase all with wider particle size distribution. However, whilst the modulus of rupture is mainly affected on going from unimodal and bimodal to trimodal distribution, superficial hardness and microhardness are mostly influenced on going from unimodal to bimodal and trimodal distribution.
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Uher, Pavel, Stanislava Milovská, Rastislav Milovský, Peter Koděra, Peter Bačík, and Vladimír Bilohuščin. "Kerimasite, {Ca3}[Zr2](SiFe3+2)O12 garnet from the Vysoká-Zlatno skarn, Štiavnica stratovolcano, Slovakia." Mineralogical Magazine 79, no. 3 (June 2015): 715–33. http://dx.doi.org/10.1180/minmag.2015.079.3.15.
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AbstractKerimasite {Ca3}[Zr2](SiFe23+)O12, a rare member of the garnet supergroup, has been identified in association with andradite–grossular and their hydrated analogues, monticellite, perovskite, clintonite, anhydrite, hydroxylellestadite–fluorellestadite, spinel, magnetite, brucite, valeriite and other minerals from a Ca-Mg skarn in the exocontact of a granodiorite porphyry intrusion in Vysoká-Zlatno Cu-Au skarn-porphyry deposit, the Štiavnica stratovolcano, Central Slovakia. Kerimasite forms euhedral-to-anhedral crystals, 2 to 100 μm across with 0.73–1.62 atoms per formula unit (a.p.f.u.) Zr (16.2–33.6 wt.% ZrO2), 0.34–0.66 a.p.f.u. Ti (4.6–9.3 wt.% TiO2), 0.01 to 0.05 a.p.f.u. Hf (0.4–1.7 wt.% HfO2: the largest Hf content reported in kerimasite), and small amounts of Sn, Sc and Nb (≤0.02 a.p.f.u.). Tetrahedral Si (0.99–1.67 a.p.f.u.; 9.8–18.1 wt.% SiO2) is balanced by 0.85–1.26 a.p.f.u. Fe3+ and by 0.46–0.76 a.p.f.u. Al. The crystals commonly show regular, oscillatory concentric zoning or irregular patchy internal textures due to Zr, Ti, Fe, Al and Si variations during growth or partial alteration and dissolution-reprecipitation. The main substitutions in kerimasite are Y(Fe,Sc)3+ + ZSi4+ = Y(Zr,Ti,Hf,Sn)4+ + Z(Fe,Al)3+ and Ti4+ = Zr4+. Associated andradite locally contains irregular Ti- and Zr-rich zones with ≤11 wt.% TiO2 and ≤4.4 wt.% ZrO2. In comparison with common Ca-rich garnets, the micro-Raman spectrum of kerimasite shows that many bands shift towards much lower wavenumbers, either due to Fe3+ substitution on the Z site or to the strong influence of neighbouring octahedrally-coordinated Zr4+ on internal vibrations of tetrahedra that share oxygens. The formation of kerimasite, monticellite, perovskite and other phases indicate a relatively Ca-rich and Si, Al-poor environment, analogous to other known occurrences of Ca-Zr garnets (Ca-rich skarns and xenoliths, carbonatites). Kerimasite and associated skarn minerals originated during contact-thermal metamorphism of Upper Triassic marl slates with limestone, dolomite, anhydrite and gypsum by Miocene granodiorite porphyry at T ≈ 700°C and P ≈ 50–70 MPa.
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Spoorenberg, A., S. Arends, M. Sinnige, and M. De Hair. "SAT0392 DIAGNOSIS OF AXIAL SPONDYLOARTHRITIS IN DAILY CLINICAL PRACTICE – A SURVEY AMONG DUTCH RHEUMATOLOGISTS." Annals of the Rheumatic Diseases 79, Suppl 1 (June 2020): 1145.1–1145. http://dx.doi.org/10.1136/annrheumdis-2020-eular.4317.
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Background:Since publication of the ASAS classification criteria for axial spondyloarthritis (axSpA) in 20091and the development of ASAS-endorsed recommendation for early referral of patients with a suspicion of axSpA,2awareness for non-radiographic (nr-) axSpA besides Ankylosing Spondylitis (AS) has increased. Still there is limited information of how nr-AxSpA is addressed in daily clinical practice.Objectives:To get insight into the diagnostic phase of axSpA in daily rheumatologic practice in the Netherlands, and to explore if nr-axSpA is addressed differently from AS.Methods:We set up a 21 multiple choice question survey for rheumatologists in the Netherlands with 5 general questions about their practice and 16 questions addressing the diagnostic phase of axSpA. The questionnaire was taken by representatives of the medical department of Novartis NL during structured face-to-face interviews. Rheumatologists in the Netherlands were invited to participate, aiming to get a sample of rheumatologists varying in geographical location and hospital type, as well as a mix of SpA-experts and non-SpA-experts. Rheumatologists gave approval for anonymous use of the data, which were entered in a database and subsequently analyzed using descriptive statistics.Results:From October 15th2019 until January 16th2020, 36 Dutch rheumatologists participated in the face-to-face survey; 6 from university hospitals, 27 from general hospitals and 3 from private care centers. Most of axSpA patients (61%) were referred by the general practitioner and mean time between referral and first visit was 2-6 weeks. More than 50% of rheumatologists reported a mean symptom duration of >1 year and in 30% even >2 years before first visit. For diagnosing axSpA rheumatologists performed in almost all cases X-pelvis (mean 100% (SD 0%) for both AS and nr-axSpA), CRP/ESR (91% (26%) for AS; 94% (22%) for nr-axSpA) and HLA-B27 (74% (40%) for AS; 86% (26%) for nr-axSpA. MRI of the SI joints was performed in 31% and 82% of patients, respectively, and about 60% of the rheumatologists used of classification criteria for diagnosing axSpA. In addition, rheumatologists marked the level of importance of several (SpA) clinical features for making the diagnosis AS or nr-axSpA (Figure 1). Most rheumatologists graded inflammatory back pain, arthritis/enthesitis/dactylits and uveitis as very important for contributing to the diagnosis. Functional impairment of the spine and male sex were mostly graded neutral or not important for making a diagnosis of axSpA. All features were graded of similar importance for the diagnosis AS and nr-axSpA, except for backpain starting before the age of 45, which was considered more important for diagnosing AS.Conclusion:This survey among Dutch rheumatologists showed that in 30% of patients referred with possible suspicion of axSpA, symptom duration still was >2 years. Almost 60% of rheumatologists make use of the ASAS classification criteria for diagnosing nr-axSpA. Therefore, for early referral awareness of axSpA in first line should enhance. Furthermore, rheumatologists should become aware that classification criteria are not similar to diagnostic criteria and cannot be used as a tick box for diagnosis.References:[1]Rudwaleit M et al, Ann Rheum Dis 2009;68:777-83, 2. Poddubnyy D et al, Ann Rheum Dis 2015;74:1483–7Acknowledgments:We would like to thank all participating rheumatologists.Disclosure of Interests:Anneke Spoorenberg: None declared, Suzanne Arends Grant/research support from: Grant/research support from Pfizer, Mark Sinnige Employee of: Current employee of Novartis Pharma B.V., Marjolein de Hair Employee of: Current employee of Novartis Pharma B.V.
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Kimura, Takafumi, Hideki Yamawaki, Yoshihiro Arimoto, Kazuto Ikeda, Masaru Ihara, and Masashi Ozeki. "High-Quality Thin Si Film By Spe Regrowth on Epitaxially Grown Spinel." MRS Proceedings 53 (1985). http://dx.doi.org/10.1557/proc-53-143.
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ABSTRACTA high-quality thin Si layer on epitaxial spinel(MgO·Al2O3) on Si substrate has been developed. It was obtained by the solid phase epitaxial (SPE) regrowth of amorphous Si with Si seed islands on the epitaxially grown spinel. The SPE-Si layer on the epitaxial spinel was superior to conventional Si on sapphire (SOS) in stacking-fault density, Hall mobility, and contamination from the insulating materials. The SPESi layer has low stacking-fault density of 10–50 cm-2, even for 0.4 μm thickness. This value is eight orders of magnitude less than that of Si on epitaxial spinel obtained by vapor phase epitaxial (VPE) growth with SiH4. The SPE-Si also has high electron Hall mobility of 880 cm2/V-s for n=5×l016 cm-3, for 1-μm-thick Si. This value is about 85% of that in bulk Si, and is higher than that in Si on spinel grown by VPE-growth and SOS. (100) spinel layer was grown on (100) Si substrate by a MgCI2-Al-HCI-CO2-H2 VPE growth system. After thermal oxidation, Si seed islands were grown on the spinel by the pyrolysis of SiH4. Amorphous Si was deposited on the Si seed islands by chemical vapor deposition (CVD) of SiH4. The SPE-Si layer was obtained by regrowth of the amorphous Si in a hydrogen atmosphere.
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Gómez, Cristian, Tushar K. Das, Sadasivan Shaji, Edén A. Rodríguez, Ana M. Guzmán, Alan Castillo, and Laura García. "Influence of Oxide Nanoparticles of Fe, Al and Si on the Sintered Magnesia for the Production of Refractory Material to Be Used in Secondary Ladle Metallurgy." MRS Proceedings 1371 (2012). http://dx.doi.org/10.1557/opl.2012.165.
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ABSTRACTIron oxide (Fe2O3, 20-40 nm), aluminum oxide (Al2O3, 50 nm) and silicon oxide (SiO2, 20-60 nm) nanoparticles were mixed in different concentrations (1 to 5 wt %) in a magnesium oxide matrix to develop new refractory matrixes as candidates in the lining of secondary ladle metallurgy. To avoid agglomeration of nanoparticles in the magnesium oxide (MgO) matrix, it was carried out a dispersion method of nanoparticles with different dispersants. After that, the powder mixture was sintered at a temperature of 1300 and 1500 °C for 4 hours. The refractory samples obtained were studied using X-ray diffraction (XRD) and scanning electron microscopy with energy dispersive X-ray spectrometer (SEM-with EDX) and also measured their density and porosity. The results showed that the samples sintered at 1500 °C with 5 wt % of Fe2O3 reached the highest density and presented the MgFe2O4 spinel-type phase. With the addition of Al2O3-nanoparticles in the MgO matrix, there were the formation of MgAl2O4 spinel phase and in the case of SiO2-nanoparticles addition it was observed the formation of Mg2SiO4 forsterite phase. It is well known that with the increase in spinel phase in the matrix, there is a significant help to retain quantities of ions of iron and nickel due to the dissolution of the slag into the refractory material extending their lining life.
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Stefanovsky, Sergey, Boris Nikonov, Boris Omelianenko, and James C. Marra. "Phase Composition and Elemental Distribution in the Vitrified U-bearing HLW Surrogate." MRS Proceedings 1265 (2010). http://dx.doi.org/10.1557/proc-1265-aa06-14.
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AbstractThe blocks of glassy material at 55 wt.% SB4 waste loading produced in a demountable cold crucible and cooled to room temperature in cold crucible and glasses cooled in a resistive furnace by a canister centerline cooling (CCC) regime were sectioned to investigate phase composition and elemental distribution between various parts of the blocks. X-ray diffraction (XRD), optical microscopy, scanning electron microscopy coupled with energy dispersive spectroscopy (SEM/EDS) and infrared (IR) spectroscopy studies revealed some difference in the texture but not in phase composition of the materials sampled from various parts of the blocks. The glass samples were composed of vitreous and spinel structure phases. Spinel was present as both skeleton-type aggregates of fine (micron- or submicron-sized) crystals segregated at early stages of melt solidification and larger (up to tens of microns) individual more regular crystals formed during slow melt cooling. There was some tendency for elemental segregation in the glass block from the cold crucible with enrichment of the deeper zones with heavier transition metal ions and depletion of Na, Cs, Ca, Al and Si. Uranium was quite uniformly distributed within zones of the block and entered the vitreous phase.
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Stefanovsky, S. V., A. G. Ptashkin, O. A. Knyazev, M. A. Zen'kovskaya, and J. C. Marra. "Cold Crucible Vitrification of Uranium-Bearing High Level Waste Surrogate." MRS Proceedings 1107 (2008). http://dx.doi.org/10.1557/proc-1107-269.
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AbstractThree tests on vitrification of U-bearing DWPF SB2 and SB4 waste surrogates (40-50 wt% waste loading) in a lab-scale (56 mm inner diameter) copper cold crucible with melt surface area of 24.6 cm2 energized from a 5.28 MHz/10 kW generator were conducted. At the feeding of the air-dry batch (3-5 wt% moisture) glass productivity and specific melt productivity achieved under steady-state conditions were 0.64 kg/h and 256 kg/(m2×h) [6150 kg/(m2×day)], respectively. Similar to previously prepared U-free products, the U-bearing vitrified SB2 (highferrous) waste product was composed of U-enriched glassy matrix and high-ferrous spinel structure phase. As expected, the vitreous phase in the vitrified SB2 waste surrogate was enriched with Na, Al, Si, P, S, Ca, Sr, Pb, U oxides and Cl, whereas spinel preferentially accumulated transition metals (iron group elements: Mn, Fe, Ni) as well as Cu and Zn oxides. Iron oxide content in the spinel phase was ∼67–71 wt %. This result was consistent with XRD data and implies that this spinel was close to magnetite with respect to chemical composition and structure. This was consistent with our previous data on characterization of glass crystalline materials containing both U-bearing and U-free SB2 waste surrogate produced in resistive furnace and cold crucibles. The vitrified SB4 (high-alumina) waste products were predominantly amorphous at waste loading of up to 50 wt %. Traces of quartz occurred in the “skull” zone. In all the products, uranium was found to be uniformly distributed within the vitreous phase. Leach rates of Na, Si, Fe, and U from the vitrified SB2 waste surrogate (50 wt % waste loading) determined by a SPFT procedure were found to be 1.38, 1.42, 0.122, and 0.841 (g×m−2×d−1), respectively.
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Oversluizen, Menno, S. M. Clark, and G. N. Greaves. "Elucidating Structural Mechanisms for Cordierite Ceramic Formation using Synchrotron Radiation." MRS Proceedings 307 (1993). http://dx.doi.org/10.1557/proc-307-39.
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ABSTRACTCr2O3 is a common nucleating agent useful for forming ceramics from oxide glasses. In this study we have used a variety of synchrotron radiation techniques to examine the atomic structure, crystallinity and microstructure of a magnesium alumino-silicate glass ceramic whose composition is close to that of the mineral cordierite, Mg2Al4Si5O13. X-ray Absorption spectra on the Cr K-edge have been performed with samples that were heat treated at different temperatures and times to examine the metamorphosis of the nucleating site. This study reveals that Cr3+ is always octahedrally coordinated with oxygen. In addition, the second nearest neighbour environment changes from an amorphous, single shell of Al/Si, but upon crystallisation, develops into a well ordered Al/Mg shell indicative of the formation of a dilute Cr spinel phase. Powder X-ray Diffraction (XRD) patterns, however, reveal that the major phase initially precipitated (˜900°C) is a stuffed quartz and from the lattice parameters that the composition is SiO2 -rich. With prolonged heat treatment a small quantity of a spinel phase emerges whose composition from its lattice parameter is close to MgAl2O4. Combined Small Angle X-ray Scattering (SAXS) and XRD establish that devitrification at these temperatures is associated with particles about 250 Å in size, on average. Energy dispersive powder diffraction patterns were collected in situ to observe changes in crystallinity with temperature and time. From these measurements the stuffed quartz phase identified at 900°C is found to be intermediate, being eventually replaced at higher temperatures by cordierite with a small quantity of spinel.
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Chen, Qi, and W. D. Griffiths. "Modification of Double Oxide Film Defects with the Addition of Mo to An Al-Si-Mg Alloy." Metallurgical and Materials Transactions B, January 5, 2021. http://dx.doi.org/10.1007/s11663-020-02038-w.
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AbstractIn this work, Mo was added into Al melt to reduce the detrimental effect of double-oxide film defect. An air bubble was trapped in a liquid metal (2L99), served as an analogy for double-oxide film defect in aluminum alloy castings. It was found that the addition of Mo significantly accelerated the consumption of the entrapped bubble by 60 pct after holding for 1 hour. 2 sets of testbar molds were then cast, with 2L99 and 2L99+Mo alloy, with a badly designed running system, intended to deliberately introduce double oxide film defects into the liquid metal. Tensile testing showed that, with the addition of Mo, the Weibull modulus of the Ultimate Tensile Strength and pct Elongation was increased by a factor of 2.5 (from 9 to 23) and 2 (from 2.5 to 4.5), respectively. The fracture surface of 2L99+Mo alloy testbars revealed areas of nitrides contained within bi-film defects. Cross-sections through those defects by Focused Ion Beam milling suggested that the surface layer were permeable, which could be as thick as 30 μm, compared to around 500 nm for the typical oxide film thickness. Transmission Electron Microscopy analysis suggested that the nitride-containing layer consisted of nitride particles as well as spinel phase of various form. The hypothesis was raised that the permeability of the nitride layers promote the reaction between the entrapped atmosphere in the defect and the surrounding liquid metal, reducing the defect size and decreasing their impact on mechanical properties.