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Journal articles on the topic 'Silicon nitride (Si3N4)'

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Published: 4 June 2021

Last updated: 18 June 2025

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Joshi, Bhupendra, Hyun Hwi Lee, Seung Ho Kim, Zheng Yi Fu, Koichi Niihara, and Soo Wohn Lee. "Boron Nitride Doped Transparent Polycrystalline Silicon Nitride Ceramics." Materials Science Forum 658 (July 2010): 428–31. http://dx.doi.org/10.4028/www.scientific.net/msf.658.428.

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The addition of h- BN to a polycrystalline Si3N4 was to increase the fracture toughness and other mechanical properties such as flexural strength and hardness of the material. The hot pressed samples were prepared from the mixture of α-Si3N4, AlN, MgO and h-BN. The composite contained from 0 to 2 wt.% BN powder with sintering aids (9% AlN + 3% MgO). The transparency, mechanical properties and microstructure of hot pressed polycrystalline Si3N4-BN composite materials were investigated by UV/VIS spectrophotometer, scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The transparency decreased with increasing the content of h-BN into Si3N4.

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Rao, R. Ramachandra, and T. S. Kannan. "Nitride-bonded silicon nitride from slip-cast Si + Si3N4 compacts." Journal of Materials Research 17, no. 2 (2002): 386–95. http://dx.doi.org/10.1557/jmr.2002.0054.

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The dispersability of Si and Si3N4 powders in aqueous media was monitored by particle-size distribution, sedimentation behavior, viscosity/rheological studies, and electrokinetic behavior [zeta potential (ZP) analysis] as a function of pH of their slips. The pH values of 4 and 8 for Si and 10 for Si3N4 resulted in optimum dispersion, characterized by minimum in sedimentation height, minimum in viscosity, and maximum in ZP. The optimum slips of Si + Si3N4 mixtures conditioned in the pH range 8 to 10 were slip cast to obtain green compacts having a density in the range of 59% to 66% theoretical value. When nitrided, these compacts yielded nitride-bonded Si3N4 products having a density of 2.06 to 2.28 g cm−3, Si3N4 bonding phase of 20–60%, and 3-point flexural strength values in the range of 50 to 150 MPa. The microstructure consisted of very fine particles as well as fibrous or whiskerlike α–Si3N4 binding phase enveloping the matrix Si3N4, in total consisting of 90% α–Si3N4 and the rest being β–Si3N4 phase.

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Zhang, Ke, Qiang Zhang, Peng Fei Wang, Ling Bai, Wei Ping Shen, and Chang Chun Ge. "Silicon Nitride/Boron Nitride Composite by Combustion Synthesis." Materials Science Forum 561-565 (October 2007): 531–34. http://dx.doi.org/10.4028/www.scientific.net/msf.561-565.531.

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Machinable silicon nitride/ hexahedral boron nitride (Si3N4/h-BN) composites were in-situ synthesized in a nitrogen (N2) atmosphere by means of combustion synthesis gas-solid reaction with silicon (Si) powder and h-BN as raw materials. The effect of the volume fraction of h-BN on the machinable properties of Si3N4/BN composite was studied. The results show that Si powder was fully nitrified and no residual Si was found. Microstructures by a scanning electron microscopy (SEM) show Columnar crystals of β-Si3N4 are the main phase and acicular crystals of h-BN disperse β-Si3N4 intergranular. With the increasing of the volume content of h-BN, the machinability of the composite increases, but the bending strength of composite decreases firstly and then increases. The lowest bending strength is 84.96MPa at 25% volume fraction of h-BN.

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Yurkov, Andrey. "Silicon Carbide–Silicon Nitride Refractory Materials: Part 1 Materials Science and Processing." Processes 11, no. 7 (2023): 2134. http://dx.doi.org/10.3390/pr11072134.

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Silicon carbide and silicon nitride materials were intensively studied in the end of the past century, yet some aspects of its physical chemistry require investigation. The strength characteristics of Si3N4-SiC refractories are moderate; however, these materials sometimes demonstrate “stress–strain” behavior, more typical for composite materials than for the brittle ceramics. These materials may be considered to be ceramic composites because they consist of big grains of silicon carbide surrounded by small grains of silicon nitride, with strict interfaces between them. There is no direct certainty whether Si3N4-SiC compositions may be called composite materials or brittle ceramic materials from the viewpoint of mechanics and strength. The balance of α/β modifications of silicon nitride in Si3N4-SiC composite material and, the occurrence and the role of silicon oxynitride Si2ON2 are also a matter of scientific interest in processing of Si3N4-SiC composite material. The same may be said about the particles of silicon nitride between the grains of silicon carbide—there is no direct understanding whether silicon nitride grains will be isometric grains or needle-like crystals.

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Zhang, Ming, Hongliang He, F. F. Xu, T. Sekine, T. Kobayashi, and Y. Bando. "Cubic silicon nitride embedded in amorphous silicon dioxide." Journal of Materials Research 16, no. 8 (2001): 2179–81. http://dx.doi.org/10.1557/jmr.2001.0296.

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A cubic silicon nitride embedded in amorphous SiO2 compound has been characterized by means of high-resolution analytical electron microscopy. The specimen was prepared from β–Si3N4 powders at a high pressure and temperature by shock wave compression. The typical high-resolution electron microscopy image from one small crystallite together with its diffractodiagram pattern indicated that the Si3N4 crystallites had a cubic symmetry. The electron energy loss spectrum from the small crystallite is very different from those of outside amorphous SiO2 phase and raw β–Si3N4 particles, and there are more N elements that were detected in this small crystallite than those in standard Si3N4.

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Jiang, Guo Jian, Jia Yue Xu, Hui Shen, et al. "Fabrication of Silicon Nitride Ceramics with Magnesium Silicon Nitride and Yttrium Oxide as Sintering Additives." Advanced Materials Research 177 (December 2010): 235–37. http://dx.doi.org/10.4028/www.scientific.net/amr.177.235.

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Si3N4 ceramics have been fabricated through pressureless sintering and hot-pressing sintering with MgSiN2-Y2O3 or only MgSiN2 as sintering additive, respectively. The effects of MgSiN2 and Y2O3 and sintering methods on sintering properties of Si3N4 ceramics were studied. The results indicate that the bend strength of Si3N4 ceramic with 5.6wt.%MgSiN2-15.8wt.%Y2O3 sintered at 1820°C for 4h could achieve 839MPa. The bend strength of Si3N4 ceramic with 4.76wt.%MgSiN2 produced by hot-pressing sintering at 1750°C for 1h under uniaxial pressure of 20MPa is 1149MPa. The thermal conductivity of the Si3N4 ceramic was 92Wm-1K-1 and could remarkably increase to 129Wm-1K-1 by prolonging the sintering time from 1 h to 12 h. The present work demonstrated that MgSiN2 additives and hot-pressing sintering were effective to improve the thermal conductivity of Si3N4 ceramic.

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Wang, E. Y., X. Pan, J. P. Mansfield, T. Kennedy, and S. Hampshire. "TEM Studies of Silicon Nitride-Silicon Carbide Nanocomposites." Microscopy and Microanalysis 3, S2 (1997): 411–12. http://dx.doi.org/10.1017/s1431927600008941.

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Si3N4/SiC nanocomposites have been shown to exhibit excellent strength and fracture toughness compared to monolithic Si3N4 materials. Recently, the microstructure and chemistry of Si3N4-based nanocomposites fabricated by hot-pressing amorphous Si-C-N precursor powders has been investigated. In the present work, our studies on the microstructure of Si3N4/SiC nanocomposites made by hot-pressing the mixture of Si3N4 and SiC commercial powders are reported.Si3N4/SiC nanocomposites were prepared by hot-pressing at 1750 °C for 1 hour at 40 Mpa in a nitrogen atmosphere, with sintering aids of 5.5 wt% Y2O3 and 3 wt% Al2O3. The details of the processing procedure have been reported elsewhere. Two different materials were investigated in this work: specimen A consisting of 5 vol% β-SiC; and specimen B consisting of 5 vol% α-SiC. TEM specimens were prepared by conventional procedures. The microstructure and chemical composition were studied in the University of Michigan Electron Microbeam Analysis Laboratory on a JEOL 2000FX.

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Brito, M. E., K. Watari, K. Hirao, and M. Toriyama. "“Special Boundaries” in Silicon Nitride With High Thermal Conductivty." Microscopy and Microanalysis 6, S2 (2000): 384–85. http://dx.doi.org/10.1017/s1431927600034413.

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Significant improvements in the fracture resistance, fracture toughness and thermal properties of silicon nitride ceramics are obtained by tailoring the microstructure. Combined use of seeding and tape casting techniques allowed the production of highly anisotropic microstructures. The seeded silicon nitrides exhibited a distinct bimodal microstructure, with large elongated β-Si3N4 grains, grown from seeds, dispersed within a fine-grained matrix. These large grains in the seeded silicon nitrides lie in the casting planes and self-align along the casting direction during tape forming process. It is here, when due to the high degree of alignment that “special boundaries” without the, otherwise, ubiquitous amorphous phase occurs. These “special” boundaries, hardly seen in three dimensionally random microstructures, are the object of the present study.Silicon nitride with high thermal conductivity of up to 120 W/mK (ref. 3) is produced by hot-pressing at 1800 °C for 2 h. powders with the following nominal composition: α-Si3N4 ;5 wt% Y203; 5 vol.% (β-Si3N4 seeds.

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Yao, Huai, Qiao Yu Xu, and Jing You Tang. "Synthesis and Stability of Cubic Silicon Nitride." Advanced Materials Research 79-82 (August 2009): 1467–70. http://dx.doi.org/10.4028/www.scientific.net/amr.79-82.1467.

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Experiments using a planar metal disc flyer driven by explosives and a cylindrical chamber was designed to synthesize cubic silicon nitride with the mixtures of α-Si3N4 and copper powders as starting materials. The ratio of transformation from α-Si3N4 to γ-Si3N4 approached to 80% percent at 45 GPa pressures and 4000K temperatures. The purity of γ-Si3N4 reached 100% after the synthesized samples were treated with hydrofluoric acid at 440K for 9-10h. High pressure sintering was carried out with a DS6×800A link-type cubic anvil apparatus at a pressure of 5.7GPa and calculated temperature of 1370-1670K over the course of 15 minutes. The result showed that γ-Si3N4 was completely transformed into β-Si3N4 at 5.7GPa, 1420-1670k and was partly transformed into β-Si3N4 at 5.7 GPa, 1370k. Micro-analysis indicated that the typical microstructure of sintered Si3N4 was elongated β-Si3N4 rod crystals in disordered orientation, the highest relative density of the sintered samples was 99.06% and Vickers hardness of them was 21.15GPa.

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Holla, M., Tzanimir Arguirov, Winfried Seifert, and Martin Kittler. "Analysis of Silicon Carbide and Silicon Nitride Precipitates in Block Cast Multicrystalline Silicon." Solid State Phenomena 156-158 (October 2009): 41–48. http://dx.doi.org/10.4028/www.scientific.net/ssp.156-158.41.

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We report on the optical and mechanical properties of Si3N4 inclusions, formed in the upper part of mc-Si blocks during the crystallization process. Those inclusions usually appear as crystalline hexagonal tubes or rods. Here we show that in many cases the Si3N4 inclusions contain crystalline Si in their core. The presence of the Si phase in the centre was proven by means of cathodoluminescence spectroscopy and imaging, electron beam induced current measurements and Raman spectroscopy. The crystalline Si3N4 phase was identified as β-Si3N4. Residual stress was revealed at the particles. While the stress is compressive in the Si material surrounding the Si3N4 particles tensile stress is found in the Si core. We assume that the stress is formed during cool down of the Si block and is a consequence of the larger thermal expansion coefficient of Si in comparison to that of β-Si3N4. Iron assisted nitridation of Si at temperatures below 1400 °C is considered a possible mechanism of Si3N4 formation.

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A., H. M. Nasib, H. Ahmad M., Nawawi Z., A. B. Sidik M., and I. Jambak M. "Electrical treeing and partial discharge characteristics of silicone rubber filled with nitride and oxide based nanofillers." International Journal of Electrical and Computer Engineering (IJECE) 10, no. 2 (2020): 1682–92. https://doi.org/10.11591/ijece.v10i2.pp1682-1692.

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This article presents a study on electrical treeing performances with its associated partial discharge (PD) and the influence of filler concentration in silicone rubber (SiR) samples which are filled with silicon dioxide (SiO2) and silicon nitride (Si3N4) as nanofillers for electrical tree growth suppression. There are many researches on electrical treeing in SiR with SiO2 nanofillers but none of the publication have reported on Si3N4 nanofillers for suppression of the electrical tree growth. In this study, the treeing experiments were conducted by applying a fixed AC voltage of 10 kV and 12 kV at power frequency of 50 Hz on unfilled SiR, SiR/SiO2, and SiR/Si3N4 nanocomposites with different filler concentrations by 1, 3, and 5 weight percentage (wt%) and the treeing parameters were observed with its correlated PD patterns. The outcome from this study found that the SiR/Si3N4 nanocomposites were able to withstand the electrical treeing better than the pure SiR or SiR/SiO2 nanocomposites. Furthermore, the increase in filler concentration improved the electrical tree performances of the nanocomposites. This finding suggests the Si3N4 can be used as filler in polymeric insulating materials for electrical tree inhibition. Meanwhile, the PD activity shows increment when the tree progresses thereby indicating correlation in both parameters which can be as key parameter for monitoring unseen treeing in non-transparent samples.

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Gao, Mei, Yong Li, Hai Xia Qin, et al. "Distribution Status of Trace Oxygen in Fe₃Si-Si₃N₄." Key Engineering Materials 680 (February 2016): 107–10. http://dx.doi.org/10.4028/www.scientific.net/kem.680.107.

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The distribution status of trace oxygen in the ferro-silicon nitride (Fe3Si-Si3N4) was investigated at the present, which was prepared by flash combustion synthesis method from FeSi75. The results showed that while the grain size of FeSi75 used in preparing Fe3Si-Si3N4 was less than0.074 mm, “active oxidation” occurred firstly, silicon was oxidized to form gaseous SiO(g), oxygen partial pressure was reduced in the system, silicon reacted with nitrogen directly to form Si3N4 while the system oxygen partial pressure approached less than 10-19MPa (T=1823K). O2(g) promoted the formation of Si3N4, Gaseous SiO(g) finally reacted with nitrogen and Si to form Si2N2O. The ferro silicon nitride was characterized by X-ray diffractometer and scanning electron microscope, the distribution of Si2N2O was uneven in the silicon nitride, and Si2N2O mainly distributed around Fe3Si or near the hole.

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Van Landeghem, Hugo, Raphaële Danoix, Mohamed Gouné, et al. "Contribution of Local Analysis Techniques for the Characterization of Iron and Alloying Elements in Nitrides: Consequences on the Precipitation Process in Fe–Si and Fe–Cr Nitrided Alloys." Materials 11, no. 8 (2018): 1409. http://dx.doi.org/10.3390/ma11081409.

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Atom Probe Tomography (APT), Transmission Electron Microscopy (TEM), and 3D mechanical calculations in complex geometry and anisotropic strain fields were employed to study the role of minor elements in the precipitation process of silicon and chromium nitrides in nitrided Fe–Si and Fe–Cr alloys, respectively. In nitrided Fe–Si alloys, an original sequence of Si3N4 precipitation was highlighted. Al–N clusters form first and act as nucleation sites for amorphous Si3N4 nitrides. This novel example of particle-simulated nucleation opens a new way to control Si3N4 precipitation in Fe–Si alloys. In nitrided Fe–Cr alloys, both the presence of iron in chromium nitrides and excess nitrogen in the ferritic matrix are unquestionably proved. Only a certain part of the so-called excess nitrogen is shown to be explained by the elastic accommodation of the misfit between nitride and the ferritic matrix. The presence of immobile excess nitrogen trapped at interfaces can be highly suspected.

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Thallapalli, Nagaveni, K. Kishore Kumar, and C. S. P. Rao. "Preparation and Characterization of Si3N4-BN Ceramic Composites by Gelcasting." Material Science Research India 13, no. 1 (2016): 28–33. http://dx.doi.org/10.13005/msri/130105.

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In this work, a novel method for the preparation of colloids has been studied for the fabrication of silicon nitride –Boron nitride composites. In the present work, the dispersion of mixed silicon nitride –Boron nitride powders in aqueous media was studied with the changes dispersant concentration, solution pH etc. Polyethylenimine (PEI) additive as a dispersant were used for Si3N4 and BN powders in aqueous media. Well-dispersed Si3N4 and BN powders in aqueous media were attained atthe 1 wt% PEI and pH 9. 40 vol% covered Si3N4/BN slurries with varying BN content was adapted for gel casting. The gel casted material waspreheated at normal room temperature, debindered at 6000C and sintered at 17000C. The sintered composite material composed mainly of alpha-Si3N4, beta-Si3N4, and h-BN. The prepared composite material shows uniform microstructure with faceted particles, α-Si3N4 and abundant pores.

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Rabenberg, Lew, J. P. Zhou, Kil-Soo Ko, and Rita Johnson. "TEM Imaging of Amorphous Silicon Oxide - Silicon Nitride - Silicon Oxide Dielectric Films." Microscopy and Microanalysis 7, S2 (2001): 1228–29. http://dx.doi.org/10.1017/s1431927600032219.

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Thin films of amorphous silicon oxide and silicon nitride are routinely used as gate dielectrics in silicon-based microelectronic devices. It is valuable to be able to image them and measure their thicknesses quickly and accurately. This brief note describes conditions that can be used to obtain accurate and reproducible TEM images of oxide-nitride-oxide (ONO) thin films.Obtaining adequate contrast differences between oxide and nitride is not trivial because they have the same average atomic number, and both phases are amorphous. As stoichiometric compounds, both SiO2 and Si3N4 would have average atomic numbers equal to 10. For SiO2, (14+2(8))/3=10, and for Si3N4, (3(14)+4(7))/7=10. Thus, the atomic number contrast between these two is weak or nonexistent. Similarly, the amorphous character prevents the use of conventional diffraction contrast techniques.However, the density of Si3N4 (3.2 g/cm3) is considerably greater than the density of SiO2 (2.6 g/cm3), reflecting the higher average coordination of N compared with O.

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Qu, Shoujiang, Aihan Feng, Lin Geng, Jun Shen, and Daolun Chen. "Silicon Nitride Whisker-Reinforced Aluminum Matrix Composites: Twinning and Precipitation Behavior." Metals 10, no. 3 (2020): 420. http://dx.doi.org/10.3390/met10030420.

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Aluminum composites reinforced with ceramic whiskers exhibited a unique combination of high specific strength and superior specific modulus. A 20 vol.% Si3N4w/Al-11.5Si-1.0Mg-0.5Cu-0.5Ni (wt.%) composite was fabricated via squeeze casting in the present study. It was observed that the addition of silicon nitride (Si3N4) whiskers in the Al-Si cast alloy promoted extensive twinning in the eutectic silicon particles due to a coupled role of thermal stresses between the matrix and silicon and residual stresses present in the composite. Double aging peaks were present in the age-hardening curves. The precipitation mechanism involved the formation of Mg2Si and Al2CuMg phases. The presence of Si3N4 whiskers in the composite retarded the nucleation process of Mg2Si precipitate while enhancing its growth rate.

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Herrmann, Mathias, Zhijian Shen, Ingrid Schulz, Jianfeng Hu, and Bostjan Jancar. "Silicon nitride nanoceramics densified by dynamic grain sliding." Journal of Materials Research 25, no. 12 (2010): 2354–61. http://dx.doi.org/10.1557/jmr.2010.0313.

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The densification behaviors of two silicon nitride nanopowder mixtures based respectively on α-Si3N4 and β-Si3N4 as the major phase constituent were studied by spark plasma sintering. Sintering conditions were established where a low viscous liquid not in equilibrium with the main crystalline constituent(s) stimulated the grain sliding yet did not activate the reprecipitation mechanism that unavoidably yields grain growth. By this way of dynamic grain sliding full densification of silicon nitride nanoceramics was achieved with no noticeable involvement of α- to β-Si3N4 phase transformation and grain growth. This processing principle opens the way toward flexible and precise tailoring of the microstructures and properties of Si3N4 ceramics. The obtained silicon nitride nanoceramics showed improved wear resistance, particularly under higher Hertzian stresses.

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Nguyen, Tue, Herbert L. Ho, David E. Kotecki, and Tai D. Nguyen. "Reaction study of cobalt and silicon nitride." Journal of Materials Research 8, no. 9 (1993): 2354–61. http://dx.doi.org/10.1557/jmr.1993.2354.

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The interaction of cobalt (Co) and low-pressure chemical-vapor-deposited silicon nitride (LPCVD Si3N4) during anneals from 200 °C−1000 °C in vacuum, Ar, and Ar–H2 ambient (95% Ar and 5% H2) has been studied. After the anneals, reduction of Si3N4 by Co to form cobalt silicide and cobalt nitride phases has been observed. Reduction of Si3N4 initially occurs at 600 °C; however, gross physical damage occurs at temperatures of ∼900 °C in Ar. The addition of hydrogen to the ambient enhances the onset of physical damage to the nitride film by as much as 200 °C. Mechanisms governing the Co/Si3N4 reaction have been proposed.

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Ding, Yong, Yuan Lu, Ke Yun, Jin’e Liu, and Nan Liang. "The Study on Porosity Controllable Filter Material for the Integrated Gasification Combined Cycle." Solid State Phenomena 315 (March 2021): 10–15. http://dx.doi.org/10.4028/www.scientific.net/ssp.315.10.

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The porous ceramic filter material is the most effective filter materials in the integrated gasification combined cycle. The porous silicon nitride due to its higher mechanical strength, as well as good corrosion resistance, is considered as a promising material in the integrated gasification combined cycle, and it were prepared directly though the SiO2 and α-Si3N4 through carbothermal reduction - pressureless sintering in nitrogen. There was a great lot weight loss in this reaction, so it was expected to create the high porosity materials. The rod-like β-Si3N4 grains and uniform pores were formed through changing the content of α-Si3N4, SiO2 and C. So high-performance and porosity controlled porous silicon nitride filter material was obtained. With an increasing in the α-Si3N4 content, the weight loss, the linear shrinkage, and the porosity decreased, the flexural strength increased accordingly. The porous silicon nitride filter material with addition of 50wt% α-Si3N4 showed a higher aspect ratio β-Si3N4 grains and better mechanical properties .

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Kumar, Deepak, and B. S. Pabla. "Characterization of the Aluminum Matrix Composite Reinforced with Silicon Nitride (AA8011/Si3N4) Synthesized by the Stir Casting Route." International Journal for Research in Applied Science and Engineering Technology 11, no. 10 (2023): 1154–60. http://dx.doi.org/10.22214/ijraset.2023.56173.

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Abstract: The result of different volume % of Silicon Nitride (Si3N4) in AA 8011 alloy fabricated through stir casting process & then tested for hardness, wear test. Energy Dispersive Spectroscopy (EDS), and Scanning Electron Microscopy (SEM) of these samples are done. It is found that the highest hardness and wear strength can be obtained with the addition of 80 μm particle size of Si3N4 with 6% of its total volume fraction. This increase in the properties is due to the increase in density caused by the addition of Si3N4 reinforcement particles. SEM study also shows that the distribution of Si3N4 with the matrix material. The maximum hardness is obtained at 40.7 HV in sample 04 having 6% of Silicon Nitride (Si3N4) and 94% of Aluminium Alloy 8011, Similarly, maximum wear is recorded in the sample having 6% of Silicon Nitride (Si3N4) and 94% of Aluminium Alloy 8011when the load is 4kg and RPM is 1800.

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Li, Cui Wei, Chang An Wang, and Yong Huang. "Mechanical Properties and Oxidation Behavior of Si₃N₄/BN Laminated Ceramics." Key Engineering Materials 280-283 (February 2007): 1869–72. http://dx.doi.org/10.4028/www.scientific.net/kem.280-283.1869.

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Laminated ceramics with high mechanical properties were fabricated in the Si3N4/BN system. The mechanical properties at elevated temperatures were tested, and the oxidation behavior during tested procedure was studied at the same time. The flexure strength of the Si3N4/BN laminated ceramics changed a little below 1000°C. The displacement-load curves appeared non-linear characteristic even at high temperature. During testing procedure at high temperature, oxidation behavior of silicon nitride and silicon carbide happened, and no oxidation product of boron nitride was found. The silicon nitride layers were oxidized to form a protective silicate scale, which prevented oxidation of the boron nitride interlayers. The stability of boron nitride was beneficial to the boron nitride interlayer to partition the silicon nitride matrix layers at high temperature.

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Wang, Jian Lei, Jiu Ming Liu та Shu Xia Ren. "Preparation of β-Phase Silicon Nitride Powders". Advanced Materials Research 650 (січень 2013): 58–60. http://dx.doi.org/10.4028/www.scientific.net/amr.650.58.

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Silicon nitride powders high in β-phase content have been prepared by direct nitriding method. The silicon powders were first milled with 30%α-Si3N4 and 4% FeCl3 for 30 minutes. Then the mixture was heat-treated at 1400°C for 2 hours in the pure nitrogen gas. The phase and the microstructure of the as-prepared product were detected by X-ray diffraction (XRD) and scanning electron microscope (SEM). The results showed that the product mainly consisted of β-Si3N4, whose content is more than 92%, and a little amount of α-Si3N4, and no silicon were detected within the detection limit.

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Bai, Ling, Xing Yu Zhao та Chang Chun Ge. "Sintering of β-Si₃N₄ Powder Prepared by Self-Propagating High-Temperature Synthesis (SHS)". Materials Science Forum 546-549 (травень 2007): 2179–82. http://dx.doi.org/10.4028/www.scientific.net/msf.546-549.2179.

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Sintering of the Self-Propagating High-Temperature Synthesis (SHS) of β-Si3N4 powder with 6.67 wt.% Y2O3 and 3.33 wt.% Al2O3 as sintering additives has been emphatically investigated using hot-press sintering process. The relative density of hot-pressed β-Si3N4 reached near to the full densification (99.43%) at 1700°C. The similar micrographs with self-reinforcing rod-like β-Si3N4 grains forming an interlocking structure were observed. The better mechanical properties of hot-pressed Si3N4, such as the hardness (16.73GPa), fracture toughness (5.72 MPa·m1/2) and bending strength (611.72MPa) values, were obtained at 1700°C. The results indicate that good sinter ability can be obtained with the cheaply SHS of silicon nitride powder for preparing silicon nitride materials, which will make the cost of silicon nitride materials lowered.

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Wang, Chong-Min, Xiao-Qing Pan та Manfred Rühle. "Origin of dislocation loops in α-silicon nitride". Journal of Materials Research 11, № 7 (1996): 1725–32. http://dx.doi.org/10.1557/jmr.1996.0216.

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Dislocation loops and stacking fault formation mechanism in α–Si3N4 have been studied by annealing α–Si3N4 powders at 1500 °C and 1750 °C. Thermally activated vacancies and the structural vacancies generated with replacement of nitrogen by oxygen have been tentatively suggested to be two sources of vacancies in α–Si3N4. From the point of view of mechanism, incorporation of these vacancies is believed to lie at the building-up stage of α–Si3N4 lattice. As a result of the vacancies agglomeration, dislocation loops and stacking faults seem to be a distinctively structural feature of α–Si3N4 fabricated by different routes [chemical vapor deposition (CVD), silicon nitridation, silica carbothermal reduction, and imide decomposition]. A general discussion has been extended to the historical controversy over the oxygen and vacancy stabilization of α–Si3N4 lattice arisen from the fact that the observed unit cell dimension of α–Si3N4 has a wide variation, and also to some related phenomena in processing of Si3N4.

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Kusunose, Takafumi, Rak-Joo Sung, Tohru Sekino, Shuji Sakaguchi, and Koichi Niihara. "High-temperature properties of a silicon nitride/boron nitride nanocomposite." Journal of Materials Research 19, no. 5 (2004): 1432–38. http://dx.doi.org/10.1557/jmr.2004.0192.

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Hexagonal graphitic BN (h-BN) is interesting as a second phase for high-temperature structural ceramics because it has the same crystal structure as graphite, for which fracture strength and Young’s modulus increase with increased temperature. In this study, high-temperature mechanical properties of Si3N4/BN nanocomposite were evaluated to clarify the effect of fine h-BN particles at elevated temperatures. As a result, we found that high-temperature strength and hardness of the nanocomposite were maintained up to high temperatures; also, its Young’s modulus increased gradually, concomitant with elevated temperatures up to 1400 °C. Finally, these properties were compared with those of monolithic Si3N4 and Si3N4/BN microcomposite.

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Chowdhury, K. Das, R. W. Carpenter, and W. Braue. "Grain boundaries in silicon nitride." Proceedings, annual meeting, Electron Microscopy Society of America 51 (August 1, 1993): 920–21. http://dx.doi.org/10.1017/s0424820100150435.

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Research on whisker/matrix interfaces and matrix grain boundaries in Si3N4 and Al2O3 composites reinforced with SiC whiskers by HREM imaging have shown that disordered layers exists in these regions. The disordered interfacial regions are often considered amorphous layers, particularly when they are thicker than ∼1nm. They appear to be discontinuous in the whisker/matrix interfaces and continuous in matrix grain boundaries. Thin amorphous layers in composites and conventionally synthesized ceramics, particularly those based on Si3N4, are expected to contain oxygen from sintering aids and powder particle surface impurities. In this paper we report the results of an investigation of silicon nitride matrix grain boundaries in Si3N4/SiC(w) composites (CMC) and polycrystalline CVD silicon nitride, using very high spatial resolution position resolved EELS and HREM imaging. Interfaces between SiC and silicon nitride in CMC materials have been discussed elsewhere.The CMC's were prepared by pressing and presintering Toyo-Soda α-silicon nitride (TS10) powder with 5.5 wt% Yttria and 1.1 wt% Alumina as sintering aids and 20 vol% β-SiC Huber whiskers at 1500°C in 0.1MPa Argon.

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Fu, L., M. J. Hoffmann, and X. Pan. "Grain Boundary Microstructure of a Hot Isostatically Pressed Silicon Nitride." Microscopy and Microanalysis 3, S2 (1997): 731–32. http://dx.doi.org/10.1017/s1431927600010540.

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Si3N4-based materials exhibit attractive mechanical properties for high-temperature applications. These properties are influenced strongly by the size and morphology of the grain boundaries and grain-boundary phase. An amorphous intergranular film (IGF) commonly exists at two grain junctions. The thickness of these IGFs sensitively depend on the chemical composition of the intergranular phase.In this work, our studies on the grain boundary microstructure of Si3N44 ceramics made by Hot Isostatically Pressing (HIPing).Si3N44 materials were densified by HIPing Si3N4 powders (UBE E-10) at 1950°C at 200 MPa for 1 hour, with sintering aids of either Y2O3 or Y2O3 + A12O3. Two materials were made: material A consisting of 2 wt% Y2O3; material B consisting of 5 wt% Y2O3 and 1 wt% A12O3. Both as-HIPed and oxided samples were investigated. TEM specimens were prepared by conventional procedures. The microstructure and chemical composition were studied on a JEOL 2000FX.

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Shan, Shao Yun, Jian Feng Yang, Ji Qiang Gao, et al. "Fabrication of Porous Silicon Nitride with High Porosity." Key Engineering Materials 336-338 (April 2007): 1105–8. http://dx.doi.org/10.4028/www.scientific.net/kem.336-338.1105.

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In this study, porous Si3N4 ceramics were fabricated by carbothermal reduction reaction between silicon dioxide and carbon. The influences of different starting powders and sintering additives on microstructure and mechanical properties were investigated. XRD analysis demonstrated the formation of single-phase β-Si3N4 except for glass phase and minor of α-Si3N4 phase. SEM analysis showed that the resultant porous Si3N4 ceramics occupied fine microstructure and uniform pore structure. The samples with fine starting powder showed fine, high aspect ratio of β-Si3N4 grains and good mechanical properties. The addition of Al2O3 accelerated the densification of porous Si3N4 ceramics. With an increasing in the sintering additive content, the porosity decreased, the flexural strength increased.

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Choi, Dae Ho, Byung Kyu Moon, Rak Joo Sung, Seung Ho Kim, and Koichi Niihara. "Mechanical and Thermal Properties of Silicon Nitride Hot Pressed with Adding Rare-Earth Oxides." Materials Science Forum 486-487 (June 2005): 181–84. http://dx.doi.org/10.4028/www.scientific.net/msf.486-487.181.

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Mechanical and thermal properties of Si3N4 ceramics with various rare-earth oxides (La2O3, CeO2, Lu2O3, Dy2O3, Sm2O3, Nd2O3, Yb2O3, and RuO2) were investigated. Flexural strength of silicon nitride with addition of 5vol% Nd2O3, CeO2, Dy2O3, and Sm2O3 showed higher value than that of silicon nitride with Lu2O3 and La2O3 added because they form denser microstructure and smaller elongated grain. Thermal conductivity of silicon nitride with an addition of 5vol% RuO2 was more enhanced than that of silicon nitride added with Nd2O3, Sm2O3, and Dy2O3 because the addition of RuO2 depressed grain growth. It is also associated with lattice oxygen governing thermal conductivity of Si3N4 when added rare-earth oxides.

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Park, Min Kyu, Ha Neul Kim, Kee Sung Lee, et al. "Effect of Microstructure on Dielectric Properties of Si₃N₄ at Microwave Frequency." Key Engineering Materials 287 (June 2005): 247–52. http://dx.doi.org/10.4028/www.scientific.net/kem.287.247.

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Silicon nitride (Si3N4) has been researched intensively because of superior mechanical properties up to high temperature. The mechanical properties of Si3N4 are strongly related to microstructure. The microstructure control of silicon nitride is well known to be a key issue for tailoring the mechanical properties of structural ceramics. This work was performed to reveal the effect of microstructure on dielectric properties at microwave frequency. Three starting powders were used fine, course a-Si3N4 and b-Si3N4. Sintering additives, 5 wt.% Y2O3, 2 wt.% Al2O3 and 1 wt.% MgO were mixed with each starting powder. Si3N4 ceramic with different b/a phase specimen were obtained by hot pressing. The post-resonator method was used for the measurement of dielectric properties, dielectric constant (e′) and dielectric loss (tand), at microwave frequency range. Silicon nitride ceramics show dielectric constant of 8.1 – 8.6 and dielectric loss 1.1 x 10-3 – 5.6 x 10-3. The effect of grain size and the role of phase on microwave dielectric properties are discussed.

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Xiao, Xiaolan, Jiayun Deng, Qiang Xiong, Qiusheng Yan, Zhengtao Wu, and Huatay Lin. "Scratch Behaviour of Bulk Silicon Nitride Ceramics." Micromachines 12, no. 6 (2021): 707. http://dx.doi.org/10.3390/mi12060707.

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Si3N4 ceramic is generally recognized as being difficult to machine due to its hardness and brittleness. It is necessary to control the normal load applied and the machined depth of the abrasive particles in order to eliminate surface/subsurface damage and defects during the grinding or polishing. In this study, scratch experiments were conducted on the polished surface of Si3N4 specimens to investigate the brittle–ductile transformation and the evolution of material removal mechanisms. In addition, the cracking behaviour of Si3N4 ceramic was characterized by indentation tests. The Vickers indentation produced cracks that exhibited good developmental integrity and geometric symmetry. The results indicate that the scratch track can be divided into three stages: the ductile regime, the brittle–ductile coexisting stage, and the brittle fracture regime. The critical loads and the corresponding penetration depths of cracking occurrence in Si3N4 were recorded. The material removal of Si3N4 ceramic was primary attributed to ductile regime removal when the load was less than 9.8 N. Microcrack initiation on the subsurface was observed when the penetration depth of the scratch tip reached 8 μm or the depth of the indentation tip reached 3.2 μm. Microcracks expanded rapidly as the load was further increased, resulting in a brittle fracture of the Si3N4 ceramic.

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Suematsu, H., J. J. Petrovic та T. E. Mitchell. "Dislocation loops in α-silicon nitride single crystals". Proceedings, annual meeting, Electron Microscopy Society of America 50, № 1 (1992): 342–43. http://dx.doi.org/10.1017/s0424820100122113.

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Silicon nitride(Si3N4) is well known to be a most promising ceramic material for high temperature structural applications. It has high strength even at 1200°C and its fracture toughness is about 5 to 7 MPa•m½. Si3N4 has been manufactured on mass production lines as the compressor rotor for turbo chargers. For high temperature use, it is important to know the deformation characteristics of the material and the role played by dislocations and other defects. However, research on the nature of defects in Si3N4 has been limited considering the importance of Si3N4. In this study, we have examined defects in single crystals of Si3N4.

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Shan, Shao Yun, Qing Ming Jia, Ya Ming Wang, and Jin Hui Peng. "Fabrication of High-Porosity Silicon Nitride Ceramics with Excellent Mechanical Properties." Advanced Materials Research 284-286 (July 2011): 1339–42. http://dx.doi.org/10.4028/www.scientific.net/amr.284-286.1339.

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High-porosity silicon nitride ceramics with excellent mechanical properties were fabricated by the carbothermal reduction of SiO2. The influences of sintering conditions on microstructure and mechanical properties were studied. The results showed that microstructure and mechanical properties of porous silicon nitride ceramics were dependent mostly on the sintering conditions. The sintered porous silicon nitride ceramics exhibited the formation of fibrous microstructure with submicrometer-sized, high-aspect ratio b-Si3N4 grains, and uniform pore structure. Porous Si3N4 ceramics with a porosity of about 70%, and a flexural strength of about 70 MPa were obtained by sintering at 1750°C, with lower rate of temperature rise and no retaining time. The high strength was attributed to fine, high-aspect ratio b-Si3N4 grains and uniform pores between grains.

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Kasuriya, Supawan, and Parjaree Thavorniti. "Preparation of Silicon Nitride-Silicon Carbide Composites from Abrasive SiC Powders." Materials Science Forum 534-536 (January 2007): 1073–76. http://dx.doi.org/10.4028/www.scientific.net/msf.534-536.1073.

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Silicon nitride - silicon carbide composite was developed by using an abrasive SiC powders as a raw material. The composites were prepared by mixing abrasive SiC powder with silicon, pressing and sintering at 1400°C under nitrogen atmosphere in atmosphere controlled vacuum furnace. The proportion of silicon in the initial mixtures varied from 20 to 50 wt%. After sintering, crystalline phases and microstructure were characterized. All composites consisted of α- Si3N4 and β-Si3N4 as the bonding phases in SiC matrix. Their physical and mechanical properties were also determined. It was found that the density of the obtained composites increased with an increase in the Si3N4 content formed in the reaction.

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Wang, Fu-Xing, Yin-Qian Cheng, and Lin-Heng Haung. "Study on Tribology of Silicon Nitride Ceramic Tappet." Journal of Tribology 115, no. 2 (1993): 295–98. http://dx.doi.org/10.1115/1.2921005.

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In order to elucidate the tribological behavior of the Si3N4 ceramic used in automobile engine, a series of tests was carried out to measure the friction coefficient and wear resistance of Si3N4 during lubricated sliding against metals. A Timken type test machine and a spring loaded wear test machine were used for this study. Tests were also conducted with metal against metal pairs for comparison. The simulation tests of hot-pressed Si3N4 Ceramic tappet against metal cam pairs were conducted on a single cam-follower test machine. The test results showed that not only that the Si3N4 ceramic has excellent wear resistance, but also that the wear of the metal parts in contact with the Si3N4 ceramic decreased. These results were supported by engine bench test results.

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Luo, Jun Ting, Kai Feng Zhang, Guo Feng Wang, and Guo Qing Chen. "Superplastic Forming of Silicon Nitride at Low Temperature." Key Engineering Materials 280-283 (February 2007): 1249–52. http://dx.doi.org/10.4028/www.scientific.net/kem.280-283.1249.

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Si3N4 ceramic bodies were prepared by liquid phase sintering (LPS) with the amorphous nano-sized Si3N4 powders. Nano-sized Al2O3 and Y2O3 powders were introduced as additives. XRD analysis showed that the sintered body consists of β-Si3N4 and Si2N2O which confirms that phase change temperature of β-Si3N4 is lower than traditional Si3N4. SEM examination showed that the grain size of sintered body is smaller than 300 nm. Superplastic forming can be undertaken at the low temperature of 1550°C in a nitrogen atmosphere when the forming velocity is less than 0.5 mm/min. The formed parts rupture when the forming velocity is 1 mm/min or the forming temperature is 1500°C. Only a few defects are observed in the blank before forming, but many cavity groups are present in the formed workpiece.

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Saponjic, Aleksandra, Sladjana Maslovara, and Milan Gordic. "Short review on thermal conductivity of silicon nitride ceramics." Thermal Science, no. 00 (2024): 187. http://dx.doi.org/10.2298/tsci240615187s.

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One of the most promising substrate materials for the next-generation power devices with high thermal conductivity is silicon nitride (Si3N4). There are several ways to improve thermal conductivity of Si3N4. Substantially higher thermal conductivities for the Si3N4 ceramics could be attained by reduction of lattice oxygen content or by the increasing the ?/? phase ratio during nitridation thus enhancing grain growth during post-sintering. The method of purification of the grains and decreasing the two-grain junction films by adding large ?-Si3N4 grains to the raw Si3N4 powder, seeding by grain growth of Si3N4 crystals in polycrystalline ceramics also improves thermal conductivity. High thermal conductivity can be further achieved by development a textured microstructure in which elongated ?-Si3N4 grains are oriented almost unidirectionally. This paper summarizes the extrinsic factors governing the thermal conductivity of Si3N4 ceramic regarding microstructural parameters such as lattice defects in single-crystal, sintering additives, change in microstructural parameters like ?/? ratio, grain size, aspect ratio, grain orientation and the morphology, composition of grain-boundary, secondary phases, processing method.

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Leal-Cruz, Ana Lilia, and Martin I. Pech-Canul. "Synthesis of Si₃N₄ from Na₂SiF₆ as a Solid Precursor: Thermodynamic Study." Materials Science Forum 560 (November 2007): 11–16. http://dx.doi.org/10.4028/www.scientific.net/msf.560.11.

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CVD silicon nitride (Si3N4) is typically produced from gas or liquid precursors containing nitrogen and silicon. The method using Na2SiF6(s) as silicon solid precursor to produce films/coatings, reinforcements and powders of silicon nitride by CVD has been recently proposed in the literature. In this investigation, a thermodynamic study is carried out using the FactSage Thermochemical Software and Databases, in order to explain the phenomena associated to the synthesis of Si3N4 with Na2SiF6 as solid precursor. Accordingly, CVD diagrams for Na2SiF6, SiF4, SiF3, SiF2, SiF, and Si both with N2 and NH3 are constructed using such a software. Thermodynamically Si3N4 can be produced from SiF4(g) or Na2SiF6(s) with ammonia. Although thermodynamic considerations show that Si3N4 cannot be produced with the use of nitrogen, experimental results in this investigation show that it is formed with both ammonia and nitrogen.

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Kim, Yoon Ho, Tohru Sekino, Hirokazu Kawaoka, Takafumi Kusunose, Tadachika Nakayama, and Koichi Niihara. "Fabrication of Silicon Nitride Ceramics with Electrical Conductivity." Materials Science Forum 486-487 (June 2005): 501–5. http://dx.doi.org/10.4028/www.scientific.net/msf.486-487.501.

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The electrical conductivity was provided to structural ceramics by controlling the grain boundary phase. We focused on the grain boundary phase of Si3N4 ceramics, which can be considered as an infinite network for conducting paths. In this study, we investigated the correlationship of the microstructure, mechanical properties, and electrical conductivity of Si3N4 ceramics with V2O5 based glasses. The Si3N4 ceramic with V2O5 based glasses were successfully fabricated by controlling the composition of grain boundary phase. Fabricated materials by a PECS method indicated a very fine microstructure. The mechanical properties of Si3N4 ceramics with V2O5 based glasses were not good compared to those of conventional Si3N4. However, the values for the SNVB and the SNVBA were four or six orders of magnitude higher at room temperature and had excellent mechanical properties compared to pure V2O5 based glasses.

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Wu, Hsing Chen, Emanuel I. Cooper, and Heng Kai Hsu. "Selective Nitride Etch by Using Fluorides in High Boiling Point Solvent." Solid State Phenomena 195 (December 2012): 50–54. http://dx.doi.org/10.4028/www.scientific.net/ssp.195.50.

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Conventional wet etching techniques for selectively removing silicon nitride (Si3N4) have utilized hot (approximately 145-180°C) aqueous phosphoric acid (H3PO4) solutions (often referred to as hot phos). The typical Si3N4:SiO2 selectivity is about 40:1 when using 85% fresh hot phosphoric acid. Advantageously, as the nitride layer is removed, hydrated silicon oxide forms and dissolves in the etchant. Consistent with Le Chatelier principle, this inhibits the additional removal of silicon oxide from the device surface; thus selectivity gradually increases with use [.

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Nishimura, Toshiyuki, Mamoru Mitomo, and Hisayuki Suematsu. "High temperature strength of silicon nitride ceramics with ytterbium silicon oxynitride." Journal of Materials Research 12, no. 1 (1997): 203–9. http://dx.doi.org/10.1557/jmr.1997.0027.

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Silicon nitride ceramics with ytterbium silicon oxynitride (Yb4Si2O7N2) as secondary phase were fabricated by hot-pressing the powder mixtures, including 50.0 to 97.0 mol% of silicon nitride with a mixture of Yb2O3 and SiO2 (Yb2O3/SiO2 = 4). Sinterability of the materials with Yb2O3 was higher than that with Y2O3 in the same composition of raw powder mixtures. High density materials were obtained under the condition of 50.0 to 89.1 mol% of silicon nitride in raw powder mixtures. Mechanical properties of silicon nitride containing 97.6 mol% of Si3N4 and 2.4 mol% of Yb4Si2O7N2 were measured. Fracture toughness measured by the indentation technique was 5.9 MPam1/2. Bending strength at room temperature and at 1500 °C was 977 MPa and 484 MPa, respectively. The silicon nitride grains consisted of highly elongated rod-like grains and thin needle-like grains. The Yb4Si2O7N2 grains were crystallized at multigrain junctions and bonded close to Si3N4 grains. High strength at high temperature is supposed to be based on the presence of crystalline Yb4Si2O7N2 having a high melting point.

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Ding, Shu Qiang, Yu Ping Zeng, and Dong Liang Jiang. "Microstructure and Strength of Oxidation-Bonded Porous Silicon Nitride Ceramics." Key Engineering Materials 353-358 (September 2007): 503–6. http://dx.doi.org/10.4028/www.scientific.net/kem.353-358.503.

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An oxidation bonding process was developed to fabricate oxidation-bonded porous silicon nitride (Si3N4) ceramics from α-Si3N4 powder in air at 1100-1400oC. Si3N4 particles are bonded by the oxidation-derived silica (SiO2) and the pores derive from the stack of Si3N4 particles and the release of N2 and SiO gas during the sintering. The microstructure of oxidation-bonded porous Si3N4 ceramics was observed. Moreover, the fracture mechanism was analyzed. Effects of the bonding phases and pores on the flexural strength were investigated. Oxidation-bonded porous Si3N4 ceramics with high flexural strength was obtained by restraining the crystallization of amorphous silica and forming the well-developed necks between Si3N4 particles.

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A., Azmi, A. A. Seman K., and Y. Lau K. "Breakdown characteristics of polyethylene/silicon nitride nanocomposites." TELKOMNIKA Telecommunication, Computing, Electronics and Control 17, no. 4 (2019): 1853–58. https://doi.org/10.12928/TELKOMNIKA.v17i4.12754.

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Silicon nitride (Si3N4) has been utilized as a nanofiller in polymeric insulation due to its good characteristics in both electrical insulation and thermal conduction properties. In this work, a comparative study was performed between unfilled polyethylene and polyethylene containing different amounts of Si3N4 nanofiller. The study showed that the low density polyethylene (LDPE) added with 15 wt% of Si3N4nanofiller could have higher breakdown strength compared to equivalent LDPE with 10 wt% of Si3N4nanofiller. Morphological characterizations of the nanocomposite samples were performed using field emission electron microscopy (FESEM) and the results showed that the breakdown performance of the investigated materials were affected by the agglomeration of Si3N4 nanoparticles.

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Schneider, J. A., S. H. Risbud, and A. K. Mukherjee. "Rapid consolidation processing of silicon nitride powders." Journal of Materials Research 11, no. 2 (1996): 358–62. http://dx.doi.org/10.1557/jmr.1996.0043.

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Using a Plasma Assisted Sintering (PAS) process, submicron size, silicon nitride powders were consolidated to >99% of the theoretical density (TD) at 1750 °C in less than 5 min with retention of the a phase and the submicron grain size. The silicon nitride powders were sintered with 5 wt.% Y2O3 and 5 wt.% Y2O3 + 5 wt. % MgAl2O4 additives. The PAS processing method for the silicon nitride additive mixtures is attractive for retention of fine-grained microstructures favorable for superplastic deformation. Post superplastic forming heat treatments to transform the α−Si3N4 to lath-like, creep-resistant β−Si3N4 is another feature of the present processing method.

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Rumbao, Ana Carolina S. Coutinho, José Carlos Bressiani, and Ana Helena A. Bressiani. "Sintering Behavior of Si₃N₄-TaC Based Composites." Materials Science Forum 498-499 (November 2005): 357–62. http://dx.doi.org/10.4028/www.scientific.net/msf.498-499.357.

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Silicon nitride was the first nitride developed for engineering applications. The excellent combination of thermomechanical properties makes silicon nitride a good candidate for applications where high hardness and mechanical properties are fundamental. However, the low fracture toughness of this material limits its use as structural material. The improve of mechanical properties of silicon nitride comes from many factors, like refined microstructure by restraining grain growth, localized stress, crack tip bridging, etc. Within these factors, microstructure formation of the silicon nitride is critically important for the final properties. The design of silicon nitride based composite materials is of particular interest because of their improved high temperature strength and fracture toughness. In this work, Si3N4-TaC particulate composite was investigated. For this study was prepared a basis composition (CB) with 90%wt a-Si3N4, 6%wt and 4%wt Y2O3 and Al2O3, respectively. TaC (20%vol) was added into CB and after mixture, in high-energy milling, the powder was compacted into pellets. The kinetics of sintering was studied by means of dilatometry. The shrinkage rate versus time and temperature curves exhibit two well-defined peaks. The first peak refers to the particle rearrangement process and the second, more pronounced, to solutionreprecipitation process. It is quite clear that the presence of TaC particles has small influence on sintering kinetics of silicon nitride. It was observed the complete a®b-Si3N4 phase transformation. The microstructure shows good homogeneity both in regard of grain size and secondary phase distribution.

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Ma, Jian, Qingyu Zeng, Lijian Zhan, Jingwen Mo, Yan Zhang, and Zhonghua Ni. "Power Generation from Salinity Gradient by Reverse Electrodialysis in Silicon Nitride Nanopores." Nano 15, no. 11 (2020): 2050148. http://dx.doi.org/10.1142/s1793292020501489.

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Solid-state nanopores have shown great potential in investigating salinity gradient energy generation as a renewable power generator. In this work, various diameter silicon nitride (Si3N[Formula: see text] nanopores were fabricated to investigate the power generation between two potassium chloride solutions with different concentration gradient ratios by reverse electrodialysis. The maximal estimated power density of a Si3N4 nanopore measured experimentally can be high to 16[Formula: see text]649Wm[Formula: see text]. To compare with the single Si3N4 nanopore, multiple nanopores array has also been investigated. The equivalent circuit model of multiple Si3N4 nanopores array generator is quantitatively constructed by massive reproducible experimental data and theoretical derivation. For nanopore array, the osmotic current basically keep a linear growth with the number of the nanopores at every concentration ratio. While, the osmotic voltage is basically independent on the number of nanopore. The power generation circuit of the nanopore array can be regarded as a parallel circuit of multiple nanopores. Power generation from concentration gradients in Si3N4 nanopores could be widely used in a variety of applications like ultra-low power devices and micro-nano electromechanical systems.

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Imada, Y., K. Kamamura, F. Honda, and K. Nakajima. "The Tribological Reaction Accompanying Friction and Wear of Silicon Nitride Containing Titanium Nitride." Journal of Tribology 114, no. 2 (1992): 230–35. http://dx.doi.org/10.1115/1.2920878.

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Effect of humidity in atmosphere gas, air, or argon, is investigated for the tribochemical reaction in Si3N4 – 23 percent TiN-Si3N4 – 23 percent TiN sliding contact system using a pin-on-plate type testing machine by reciprocal movement of pin against plate. An examination is also conducted on Si3N4 – Si3N4 couple in comparison with the above system. The experimental results have shown that the wear rate decreases with increasing humidity, and the wear property is somewhat improved by adding a suitable amount of TiN to Si3N4. Reaction products formed on the interface under the sliding contact are analysed by using EPMA and XPS. It is confirmed that SiO2 (or TiO2) is produced on the surface during friction and wear, and the amount of SiO2 (or TiO2) increases with the increase of humidity. Formation of NH3 caused by development of tribochemical reaction on friction surface is examined by a spectrometric study using Nessler’s reagent. The results show that the formation of NH3 is connected directly with the amount of SiO2 (or TiO2), and that three types of formation rate are observed depending on the humidity.

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Palmer, Michael J., R. Wayne Johnson, Mohammad Motalab, Jeffrey Suhling, and James D. Scofield. "Development of a Silicon Nitride High Temperature Power Module." Additional Conferences (Device Packaging, HiTEC, HiTEN, and CICMT) 2011, HITEN (2011): 000172–79. http://dx.doi.org/10.4071/hiten-paper7-rwjohnson.

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Silicon nitride (Si3N4) offer potential advantages as a substrate for high temperature power packaging. Si3N4 has higher fracture strength than alumina and aluminum nitride. The coefficient of thermal expansion (CTE) of Si3N4 is ~3 ppm/°C and the thermal conductivity ranges from 30–50W/m-K. Active metal brazed Cu-Si3N4 substrates are commercially available for power modules. However, the large mismatch in CTE between Si3N4 and Cu results in ceramic fracture and delamination with the wide temperature thermal cycling ranges encountered in high temperature applications. In this work Cu-Carbon and Cu-Mo metal matrix composites have been investigated to reduce the CTE mismatch. The process details are presented along with finite element modeling of the proposed structure. Ultimately, the proposed structure was unsuccessful.

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Park, Chan, Kook Soo Bang, Kwon Taek Lim, Dong Soo Park, and Hai Doo Kim. "The Effect of Nitrogen Partial Pressure on Microstructure of Reaction Bonded Silicon Nitride." Solid State Phenomena 121-123 (March 2007): 231–34. http://dx.doi.org/10.4028/www.scientific.net/ssp.121-123.231.

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The interaction between gas atmosphere and silicon during reaction bonded silicon nitride(RBSN)process leads to a non-uniform band formation of alpha silicon nitride. The reaction layer, α -Si3N4, was formed near the surface of the sample in the early stage of RBSN. Reactive nitrogen gas was supplied as static state using computer controlled gas delivery system. The formation of α -Si3N4 band near the surface of the sample can be explained thermodynamically, based on the nitrogen partial pressure in the gas mixtures.

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Suematsu, H., J. J. Petrovic та T. E. Mitchell. "Stacking faults in deformed α-silicon nitride single crystals". Proceedings, annual meeting, Electron Microscopy Society of America 51 (1 серпня 1993): 916–17. http://dx.doi.org/10.1017/s0424820100150411.

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Silicon nitride(Si3N4) is well known for its high toughness and strength. This is the reason why it is selected for ceramic turbo charger rotors in automobile engines. However, the high strength of most sintered Si3N4 products drops above 1200°C because sintering aids like Y2O3 and MgO are required which form glassy phases with low melting points on the grain boundaries. This secondary phase degrades the high temperature characteristics of Si3N4. In order to overcome this deficiency, much work has been reported which aims at crystallizing or removing the glassy phase. If this aim could be successful, resulting in an increase in high temperature strength, other processes would determine the high temperature performance of Si3N4, such as diffusional creep and dislocation slip. Line and planar defects in Si3N4 play an important role in such the processes particularly in slip, however, available knowledge about them is limited. In the present work, stacking faults in deformed Si3N4 single crystals are investigated using high resolution electron microscopy(HREM).

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