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Статті в журналах з теми "NiAl-Al2O3":
1
Hwang, Chii-Shyang, and Tien-Jui Liu. "Microstructure and mechanical properties of NiAl/Al2O3 composites." Journal of Materials Research 14, no. 1 (January 1999): 75–82. http://dx.doi.org/10.1557/jmr.1999.0013.
Анотація:
To improve mechanical properties of NiAl, a method for making NiAl matrix composites containing oxide ceramics is introduced. The method involves oxidation of NiAl powder in air to form a thin and uniform oxide scale, mainly Al2O3, on the NiAl particles. The Al2O3 contents increase with increasing oxidation temperature. The NiAl/Al2O3 composites are then formed by hot-pressing the oxidized NiAl powder under vacuum atmosphere. Al2O3 inhibits the grain growth of NiAl during the hot-pressing. The residual stress and the Ni-rich NiAl composition exist in the hot-pressed NiAl/Al2O3 composites. Strength and toughness data on NiAl/Al2O3 composites indicate that the use of oxidation of NiAl powder is a viable technique for improving these properties over that of monolithic NiAl.
2
Davies, I. J., G. Pezzotti, A. Bellosi, D. Sciti, and S. Guicciardi. "Mechanical Behaviour of Nickel Aluminide Reinforced Alumina (AL2O3-NiAl) Composites." Advanced Composites Letters 11, no. 6 (November 2002): 096369350201100. http://dx.doi.org/10.1177/096369350201100601.
Анотація:
The microstructure and mechanical properties of hot-pressed alumina (Al2O3) matrix composites containing 20, 35, or 50 vol% of nickel aluminide (NiAl) were investigated. The mean Al2O3 grain size was found to decrease from approximately 2.0 μm (monolithic Al2O3) to 1.0 μm for the composite containing 50 vol% NiAl. Composite flexural strength values were lower than both the monolithic Al2O3 and NiAl and attributed to the weakly bonded NiAl particles acting as flaw origins. In contrast to this, the fracture toughness increased with NiAl volume fraction to a maximum of 4.90 MPa·m1/2, thus confirming the toughening effect of NiAl addition on Al2O3 ceramics, with the slope of the rising R-curve for the composite being approximately 8 times that of monolithic Al2O3.
3
Konopka, Katarzyna, Marek Krasnowski, Justyna Zygmuntowicz, Konrad Cymerman, Marcin Wachowski, and Paulina Piotrkiewicz. "Characterization of Al2O3 Samples and NiAl–Al2O3 Composite Consolidated by Pulse Plasma Sintering." Materials 14, no. 12 (June 19, 2021): 3398. http://dx.doi.org/10.3390/ma14123398.
Анотація:
The paper describes an investigation of Al2O3 samples and NiAl–Al2O3 composites consolidated by pulse plasma sintering (PPS). In the experiment, several methods were used to determine the properties and microstructure of the raw Al2O3 powder, NiAl–Al2O3 powder after mechanical alloying, and samples obtained via the PPS. The microstructural investigation of the alumina and composite properties involves scanning electron microscopy (SEM) analysis and X-ray diffraction (XRD). The relative densities were investigated with helium pycnometer and Archimedes method measurements. Microhardness analysis with fracture toughness (KIC) measures was applied to estimate the mechanical properties of the investigated materials. Using the PPS technique allows the production of bulk Al2O3 samples and intermetallic ceramic composites from the NiAl–Al2O3 system. To produce by PPS method the NiAl–Al2O3 bulk materials initially, the composite powder NiAl–Al2O3 was obtained by mechanical alloying. As initial powders, Ni, Al, and Al2O3 were used. After the PPS process, the final composite materials consist of two phases: Al2O3 located within the NiAl matrix. The intermetallic ceramic composites have relative densities: for composites with 10 wt.% Al2O3 97.9% and samples containing 20 wt.% Al2O3 close to 100%. The hardness of both composites is equal to 5.8 GPa. Moreover, after PPS consolidation, NiAl–Al2O3 composites were characterized by high plasticity. The presented results are promising for the subsequent study of consolidation composite NiAl–Al2O3 powder with various initial contributions of ceramics (Al2O3) and a mixture of intermetallic–ceramic composite powders with the addition of ceramics to fabricate composites with complex microstructures and properties. In composites with complex microstructures that belong to the new class of composites, in particular, the synergistic effect of various mechanisms of improving the fracture toughness will be operated.
4
Afandi, N. F., Abreeza Manap, Halina Misran, S. Z. Othman, and N. I. M. Pauzi. "Characterizations of NiAl-Al2O3 Produced Using Gel Combustion Synthesis Method." Applied Mechanics and Materials 761 (May 2015): 457–61. http://dx.doi.org/10.4028/www.scientific.net/amm.761.457.
Анотація:
NiAl is widely used for elevated temperature application because it gives better properties, especially in the gas turbine application. This study was done in order to investigate the effects of calcination temperature on NiAl and α-Al2O3 formation using gel combustion synthesis method. This method used fatty alcohol and fatty acid ester for producing NiAl powders. X-Ray diffraction patterns of calcined samples exhibited NiAl and α-Al2O3 at temperature 1050°C. Therefore, nanostructured NiAl-α- Al2O3 can be successfully produced with the gel combustion method using less expensive and more environmental friendly fatty alcohol and fatty acid ester as fuels.
5
Zhang, X. J., and Yan Niu. "Oxidation of Four NiAl-Ag Alloys at 900°C in 1 Atm O2." Materials Science Forum 475-479 (January 2005): 775–78. http://dx.doi.org/10.4028/www.scientific.net/msf.475-479.775.
Анотація:
Small amounts of silver have been added to the intermetallic compound β-NiAl for the purpose of improving its mechanical properties. Four ternary NiAl-Ag alloys NiAl-0.5Ag, NiAl-1Ag, NiAl-5Ag and NiAl-10Ag (at.%), and an Ag-free β-NiAl have been oxidized at 900oC for 24 h in 1 atm O2 to study the effect of the presence of silver on the oxidation of β-NiAl. The kinetics of all the alloys were generally composed of two main parabolic stages with slightly larger parabolic rate constants for the second stage, except for NiAl-10Ag, which has an instantaneous parabolic rate constant decreasing with time. A continuous external layer of Al2O3 formed on all the alloys. In particular, the scales formed on NiAl-5Ag and NiAl-10Ag contained a thin and discontinuous layer of silver at the alloy/Al2O3 interface. Furthermore, NiAl-10Ag formed also isolated Ag particles or even a discontinuous Ag layer occasionally surmounting the Al2O3 scale. The addition of minor amounts of silver does not affect significantly the oxidation of β-NiAl, because silver is essentially present as a second phase due to its very small solubility in this intermetallic compound.
6
Zygmuntowicz, Justyna, Katarzyna Konopka, Marek Krasnowski, Paulina Piotrkiewicz, Jan Bolek, Marcin Wachowski, Radosław Żurowski, and Mikołaj Szafran. "Characterization of Al2O3 Matrix Composites Fabricated via the Slip Casting Method Using NiAl-Al2O3 Composite Powder." Materials 15, no. 8 (April 16, 2022): 2920. http://dx.doi.org/10.3390/ma15082920.
Анотація:
This work aimed to characterize Al2O3 matrix composites fabricated by the slip casting method using NiAl-Al2O3 composite powder as the initial powder. The composite powder, consisting of NiAl + 30 wt.% Al2O3, was obtained by mechanical alloying of Al2O3, Al, and Ni powders. The composite powder was added to the Al2O3 powder to prepare the final powder for the slip casting method. The stained composite samples presented high density. EDX and XRD analyses showed that the sintering process of the samples in an air atmosphere caused the formation of the NiAl2O4 spinel phase. Finally, the phase composition of the composites changed from the initial phases of Al2O3 and NiAl to Al2O3, Ni, and NiAl2O4. However, in the area of Ni, fine Al2O3 particles remaining from the initial composite powder were visible. It can be concluded that after slip casting, after starting with Al2O3 and the composite powder (NiAl-Al2O3) and upon sintering in air, ceramic matrix composites with Ni and NiAl2O4 phases, complex structures, high-quality sintered samples, and favorable mechanical properties were obtained.
7
Chmielewski, M., S. Nosewicz, K. Pietrzak, J. Rojek, A. Strojny-Nędza, S. Mackiewicz, and J. Dutkiewicz. "Sintering Behavior and Mechanical Properties of NiAl, Al2O3, and NiAl-Al2O3 Composites." Journal of Materials Engineering and Performance 23, no. 11 (August 12, 2014): 3875–86. http://dx.doi.org/10.1007/s11665-014-1189-z.
8
Konopka, Katarzyna, Justyna Zygmuntowicz, Marek Krasnowski, Konrad Cymerman, Marcin Wachowski, and Paulina Piotrkiewicz. "Pulse Plasma Sintering of NiAl-Al2O3 Composite Powder Produced by Mechanical Alloying with Contribution of Nanometric Al2O3 Powder." Materials 15, no. 2 (January 6, 2022): 407. http://dx.doi.org/10.3390/ma15020407.
Анотація:
NiAl-Al2O3 composites, fabricated from the prepared composite powders by mechanical alloying and then consolidated by pulse plasma sintering, were presented. The use of nanometric alumina powder for reinforcement of a synthetized intermetallic matrix was the innovative concept of this work. Moreover, this is the first reported attempt to use the Pulse Plasma Sintering (PPS) method to consolidate composite powder with the contribution of nanometric alumina powder. The composite powders consisting of the intermetallic phase NiAl and Al2O3 were prepared by mechanical alloying from powder mixtures containing Ni-50at.%Al with the contribution of 10 wt.% or 20 wt.% nanometric aluminum oxide. A nanocrystalline NiAl matrix was formed, with uniformly distributed Al2O3 inclusions as reinforcement. The PPS method successfully consolidated NiAl-Al2O3 composite powders with limited grain growth in the NiAl matrix. The appropriate sintering temperature for composite powder was selected based on analysis of the grain growth and hardness of Al2O3 subjected to PPS consolidation at various temperatures. As a result of these tests, sintering of the NiAl-Al2O3 powders was carried out at temperatures of 1200 °C, 1300 °C, and 1400 °C. The microstructure and properties of the initial powders, composite powders, and consolidated bulk composite materials were characterized by SEM, EDS, XRD, density, and hardness measurements. The hardness of the ultrafine-grained NiAl-Al2O3 composites obtained via PPS depends on the Al2O3 content in the composite, as well as the sintering temperature applied. The highest values of the hardness of the composites were obtained after sintering at the lowest temperature (1200 °C), reaching 7.2 ± 0.29 GPa and 8.4 ± 0.07 GPa for 10 wt.% Al2O3 and 20 wt.% Al2O3, respectively, and exceeding the hardness values reported in the literature. From a technological point of view, the possibility to use sintering temperatures as low as 1200 °C is crucial for the production of fully dense, ultrafine-grained composites with high hardness.
9
Lee, W. Y., Y. W. Bae, and K. L. More. "Synthesis of functionally graded metal-ceramic microstructures by chemical vapor deposition." Journal of Materials Research 10, no. 12 (December 1995): 3000–3002. http://dx.doi.org/10.1557/jmr.1995.3000.
Анотація:
A composite microstructure consisting of small α-Al2O3 particles dispersed in a β-NiAl coating matrix was synthesized by chemical vapor deposition (CVD). White the surface of a pure Ni substrate was being reacted with AlCl3 and H2 to form β-NiAl at a temperature of 1050 °C, the partial pressure of CO2 in the reactor was controlled via pulsing to nucleate and disperse 50 to 500 nm α-Al2O3 particles in the β-NiAl matrix. The relative amount of the α-Al2O3 phase increased with coating thickness as the rate of the β-NiAl formation decreased with time. These experimental observations suggest that the synthesis of a graded composite microstructure by the CVD method is feasible.
10
Ramdan, Raden Dadan, Budi Prawara, and Rochim Suratman. "Thermal Oxidation of NiAl-Al2O3 Coated on Mild Carbon Steel." Advanced Materials Research 488-489 (March 2012): 437–41. http://dx.doi.org/10.4028/www.scientific.net/amr.488-489.437.
Анотація:
Thermal oxidation is believed as an important phenomenon that naturally occurs on material subjected to elevated temperature such as NiAl-Al2O3 coated material. In the present study, thermal oxidation on this coated layer was prepared by heating processes of NiAl-Al2O3 coated on mild carbon steel. Deposition of NiAl-Al2O3 was performed by high-velocity oxy fuel (HVOF) process, whereas subsequent heating processes were performed at 3 different temperatures 600oC, 800oC and 1000oC. After the process, the effects of this thermal oxidation process on the phases formation, microstructure and qualitative toughness of thermally sprayed NiAl-Al2O3 coating were investigated. The results showed that significant amount of NiAl-Al2O3 phase was transformed into NiO phase by heating process at temperature higher than 800°C. In addition, decreasing of thickness of the coating layer was also found as the service temperature increases from 800 to 1000oC. Increasing of hardness was also observed as the heating temperature increases, which is predicted due to the formation of excessive oxide on the coating layer that in turn might impart the toughness of this layer. These conditions suggested that a careful determination of service temperature have to be taken in order to avoid excessive oxidation of the coating layer.
Дисертації з теми "NiAl-Al2O3":
1
Bihr, Jean-Claude. "Le Matériau composite NiAl-Al2O3." Phd thesis, Université Sciences et Technologies - Bordeaux I, 1996. http://tel.archives-ouvertes.fr/tel-00149385.
Анотація:
Les industries aéronautiques tentent de mettre au point de nouvelles structures plus résistantes et surtout réutilisables en vue d'accélérer la conquête de l'espace. A cet effet, le matériau composite à matrice intermétallique NiAl renforcée par des fibres longues d'alumine semble prometteur et adapté à ces applications. Les travaux présentés concernent a la fois l' élaboration du composite par infiltration liquide sous pression de gaz et l'étude du couplage fibre-matrice (F/M), phénomène prépondérant qui gouverne les caractéristiques macroscopiques du matériau. Le couplage a été étudié par le biais de la microscopie électronique en transmission et de la spectroscopie de photo-électrons X ; une approche thermodynamique du couplage a ete obtenue au travers de l'étude de mouillabilite du renfort par la matrice. Ces différentes caractérisations des interfaces et interphases sont correlées les unes avec les autres pour permettre une compréhension globale des phénomenes de couplage a l'interface F/M.
2
Zhong, Yunlong [Verfasser]. "Interface Structure, Interface Properties and Tensile Properties of Single Crystalline Al2O3 Fiber Reinforced NiAl and IP75 Matrix Composites / Yunlong Zhong." Aachen : Shaker, 2008. http://d-nb.info/1164341332/34.
3
Troncy, Romain. "Synthesis and high-temperature behavior of self-restoring coatings." Thesis, La Rochelle, 2021. http://www.theses.fr/2021LAROS034.
Анотація:
La sélection des matériaux utilisés dans les parties chaudes des moteurs aéronautiques ou dans les centrales de production d’énergie est devenue un enjeu crucial au vu des impératifs écologiques et économiques. L’un des composants critiques de ces systèmes sont les aubes de turbine dont la tenue mécanique est assurée par la nature des substrats employés (aciers et superalliages à base nickel). Cependant, leur tenue environnementale nécessite l’application de revêtements protecteurs source d’Al capables de former de barrières d’oxyde (Al2O3) imperméables à l’attaque externe par oxydation et corrosion aux hautes températures. L’épuisement de l’Al pour former l’oxyde et par interdiffusion avec le substrat conduit inexorablement à la perte de protection. Ainsi, des structures spécifiques de revêtement telles les barrières de diffusion peuvent alors être mises en place pour augmenter la durée des vies des aubes au détriment de leurs propriétés mécaniques et de coûts élevés de fabrication et environnementaux. Durant cette étude, des nouvelles voies originales de synthèse des revêtements de diffusion d’aluminium « autorégénérants » ont été étudiées. Ces revêtements disposent d’une structure composite, avec une matrice de phases intermétallique (NixAly) renforcée par des microréservoirs constitués d’un cœur (NixAly) et d'une paroi en Al2O3 à travers laquelle l’Al du cœur peut ravitailler la matrice et maintenir une concentration globale en Al suffisamment élevée dans la matrice capable de former la couche externe protectrice d’Al2O3.Nos études démontrent que les réactions aluminothermiques entre du NiO et l’Al permettent de former un tel revêtement autorégénerant avec une barrière de diffusion à l’interface substrat/revêtement lorsque le Ni est initialement pré-oxydé à 1100°C pendant 2h. Néanmoins, aucun compromis n’a été trouvé pour former des revêtements sans NiO résiduel qui pourrait compromettre l’adhérence du revêtement au substrat. En revanche, une voie électrochimique permet d’incorporer de microparticules d’Al3Ni2 dans des électrodépots de Ni. A la suite d’un traitement d’aluminisation par barbotine, les microparticules préoxydées s’incorporent de manière homogène dans un revêtement de β-NiAl. Après traitement d’oxydation isotherme à 1000°C durant 48h, ce revêtement par voie électrodéposition + aluminisation présente une teneur en aluminium supérieure à 40 at%, ce qui est supérieur à un revêtement de diffusion absent de microréservoirs démontrant ainsi le caractère autorégénerant des nouveaux revêtementsThe selection of materials used in the hot parts of aeronautical turbines or in power plants has become a crucial issue in view of ecological and economic imperative. Turbine blades are amongst the most critical components. Their mechanical resistance is ensured by the substrate itself (steels and Ni alloys and superalloys). However, their low environmental resistance requires the application of protective coatings delivering Al to form oxide barriers blocking the external oxidative and corrosive attack. Upon exposure at high temperatures, Al depletes from the coating by oxidation to grow the oxide scale and by interdiffusion with the substrate’s elements resulting in the loss of protection. Some specific coating structures like the diffusion barriers have been investigated in the past but the overall mechanical properties are lowered and the fabrication and environmental costs are high. Therefore, a pioneering and original investigation has been conducted to synthesize “self-regenerating” aluminum diffusion coatings. These coatings are characterized by a composite structure whereby the matrix made of NixAly intermetallic phases is strengthened with microreservoirs made of NixAly core and an Al2O3 shell through which Al diffuses out to maintain the adequate Al concentration in the matrix, hence to stabilize the external protective Al2O3 scale.Our studies demonstrate that the aluminothermic reactions between NiO and Al lead to the formation of such a self-regenerating coating with an interdiffusion barrier at the coating/substrate interface whenever Ni is preoxidized at 1100°C for 2h beforehand. However, all the coatings sintered through this method possess residual NiO, which may compromise their adherence to the substrate. In contrast, the use of electrochemical methods allows to incorporate Al3Ni2 microparticles in the NI electrodeposits. With a subsequent slurry aluminizing treatment, the preoxidized particles incorporate homogeneously in a β-NiAl coating matrix. After exposure at 1100°C for 48h in air, the Al content in the self-regenerating coatings is greater than 40 at% as opposed to the micro-reservoirs-free aluminide coating allowing to demonstrate the self-regenerating property of these new coatings
4
Tyler, Samson. "Modelling the Effects of Element Doping and Temperature Cycling on the Fracture Toughness of β-NiAl / α-Al2O3 Interfaces in Gas Turbine Engines". Thèse, Université d'Ottawa / University of Ottawa, 2013. http://hdl.handle.net/10393/23685.
Анотація:
This document describes work performed related to the determination of how elemental additions
affect the interfacial fracture toughness of thermal barrier coatings at the bond coat/thermally grown oxide interface in gas turbines. These turbines are exposed to cyclical thermal loading, therefore a simulation was designed to model this interface in a temperature cycle between 200 K and 1000 K that included oxide growth between 2 μm and 27 μm. The fracture toughness of this interface was then determined to elucidate the function of elemental additions. It was shown that minimal concentrations of atomic species, such as hafnium and yttrium cause notable increases in the toughness of the bond coat/thermally grown oxide interface, while other species, such as sulphur, can dramatically reduce the toughness. Furthermore, it was shown that, contrary to some empirical results, the addition of platinum has a negligible effect on the fracture toughness of this interface.
5
Shih-Kai, Weng, and 翁勢凱. "Wear Resistance of NiAl/Al2O3 Composites." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/17950341821774896099.
Анотація:
碩士國立臺灣大學
材料科學與工程學研究所
88
The objective of this work is to study the sliding wear behavior of NiAl/Al2O3 composites. The composites were prepared by hot-pressing in vacuum. The NiAl/Al2O3 composites were then brazed onto a AISI 1045 carbon steel in vacuum to enhance the heat relief produced during wear test. Dry pin-on-wheel wear test were conducted, SKD11 and diamond wheels are used as contact surface materials. The wear behavior and the work hardening on the surface were investigated. The result shows that the wear mechanisms against SKD11 wheel are dominated by abrasive and adhesive wear. The wear rates of composites are decreased with the increase of Al2O3 content; however, the friction force and mean reference temperature are increased with the increase of Al2O3 content. The wear mechanism against diamond wheel is dominated by abrasive wear, but there is no relationship with the increase of Al2O3 content. The wear rates of the composites containing 100~80 v% NiAl are low due to the block and blunt of the diamond wheel induced by the presence NiAl debris. The composites containing 60~40 v% NiAl have the poorest wear resistant because the pull-out of NiAl and Al2O3 particles. However, the wear rates of composites containing below 40 v% NiAl show no relationship with the NiAl content. It may be related to the pile-up of Al2O3 particles during wear. On the aspect of work hardening, the surface of pure NiAl is hardened by wearing against diamond or SKD11 wheels. A maximum degree of work hardening is produced against SKD11 wheel, and the degree of work hardening shows no clear trend with the increase of Al2O3 content in the NiAl/Al2O3 composites. The size of debris of the composite containing 20 v% Al2O3 content is the biggest. It’s primarily due to the composite has the highest toughness and strength.
6
TSAI, CHEN-HUNG, and 蔡政宏. "Mechanical properties of Al2O3/NiAl composite." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/71565420473299278700.
Анотація:
碩士國立臺灣大學
機械工程學系
85
Structural ceramic (also named Engineering ceramic) is a newly developedmaterial. Compared with metal for structure, it demonstrates manyexcellent physical and mechanical properties. Such as low density, lowcoefficient of expansion,low heat transfer coefficient, high Young'smodulus, high hardness, high compress strength, and good corrosion, oxidization,and creep resistance. Howrver, extreme brittleness is the primany obstacleto its application in engineering. Alumina is the typical material of ceramic. It is execellent for its high srengthand good ability to resist corrosion and oxidization. However,alumina alsopossess the weakness of low toughness.By adding reinforcement, its strengthand toughness can be improved. For example, the fracturetoughness can be increased by adding the metallic reinforcement. However, theoxidization resistance and the property of low density will be sacrificed.Therefore, it will be a target for researchers to choose areinforcement that will improve the weaknesses of the material and keep itselementary properties at the same time. Owing to its low density,easy to conduct heat, and excellent oxidization resistance,NiAl is chosen as a reinforcement in this study. To make a sample, we add NiAl particleinto alumina matrix evenly, from the mixed powder into the initial sample bydie-pressing method, and then sinter it in argon atmosphere at 1500℃. After sintering and milling, we proceed the following experiments: phase identificatinoby X-ray, measurement of mechanical and physical properties (including density,flexural strength, and fracture toughness)in room temperature, strength and toughnessof the samples after oxidization, and properties of the composite after thermalshock. By observing the microstructure of the samples, We tempt to find out thecauses that effect strength and toughness of the composit. Because of the complexity of making ceramic materials and time consumingprocess, we try to use the remaining material with other materials glued toboth ends to reduced the processing time and procedure.Thus, we can reusethe material and conduct the experiments repeatedly. Meanwhile, we comparethe data with that we got from experiment by standard sample. key words：fracture toughness, NiAl metallic compound ,methanical properties,
7
Chen, Yi-Ren, and 陳怡仁. "Preparation and oxidation behavior of NiAL/Al2O3 composites." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/47330474327285717727.
Анотація:
碩士國立成功大學
材料科學(工程)學系
86
NiAl介金屬化合物與其他超合金相比較，具有低密度、高融點、高強度 以及較佳的抗氧化性等優點，因此成為航太工業上深具潛力的結構材料。 前人曾利用粉末預先氧化方法與控制晶粒大小的方法製成NiAl/Al2O3複合 材料，該複合材料具有優於NiAl者的機械性質與高溫強度。為繼續瞭解 NiAl材料及NiAl/Al2O3複合材料在高溫時的氧化行為，本研究利用前述二 種方法製成NiAl/Al2O3複合材料，檢討預先氧化的溫度和晶粒的尺寸對於 該材料在1000℃/24h長時間高溫氧化的影響。 本研究主要以熱重分析儀 （Thermogravimetric analyzer，TGA）進行實驗，以檢測試樣在高溫氧 化時之重量增加量與增重的速率，來評定該試樣的抗氧化性質是否良好。 實驗結果顯示，NiAl/Al2O3複合材料的高溫氧化行為可分為二階段進行： 氧化開始後的十小時間，NiAl/Al2O3複合材料表面形成氧化膜的速率（即 熱重曲線的斜率）較快，十小時以後的第二階段，因氧化膜逐漸長成緻密 的保護膜使得氧化速率減緩。NiAl粉末經過適當的預先氧化而製成的 NiAl/Al2O3複合材料，其氧化速率低於NiAl材料。在本實驗中，經過分級 為7mm的NiAl粉末，再以650℃/2h預先氧化後，形成的NiAl/Al2O3燒結體 有最佳的抗氧化性。 另一方面，由於NiAl的價格較為昂貴，為降低製作 NiAl/Al2O3複合材料的成本，吾人亦嘗試以較為廉價的Ni、Al元素粉末與 強化用的Al2O3粉末為起始原料，利用反應燒結的方式來合成NiAl/Al2O3 複合材料。此實驗是藉由製程條件的改變，以尋求一個最佳的反應燒結製 程。實驗結果顯示，以2atm的Ar氣氛、15℃/min昇溫速度進行反應燒結， 所得的NiAl/Al2O3燒結體之形狀與緻密性，會比在真空下、以5℃/min昇 溫速率進行反應燒結的燒結體來的好。 然而，以反應燒結製成的最佳 NiAl/Al2O3燒結體，其相對密度僅有89.8％，導致其機械性質與抗氧化性 並不好，甚至遠低於以預先氧化法製成的緻密燒結體的性質。 Compared with other superalloys, Nickel aluminide compound (NiAl) has many advantages such as low density, high melting point, high strength, and excellentoxidation resistance. Therefore, NiAl is the most potential material for application in aerospace industry. Some works have been done by using of the methods of powder pre-oxidation and controlling grain sizes to prepare NiAl/Al2O3 composites, which have better mechanical properties and elevated temperature strength than that of NiAl. To understand continuous the monolithicof NiAl and understand the oxidation behavior of NiAl/Al2O3 composites at high temperatures, two methods prescribed above are used to produce the monolithic NiAl and NiAl/Al2O3 composites. Then, the effects of pre-oxidation and controlsof grain size on the oxidation behavior of monolithic NiAl and NiAl/Al2O3 composites at 1000℃ for 24h are investigate. The thermogravimetric analyzer is used to determined the weight gain and the oxidation rate of NiAl/Al2 O3 composites. The results show that two stages can beobserved in the oxidation behavior of NiAl/Al2O3 composites. In the first stage of initial ten hours, oxides formed on the surface of NiAl/Al2O3 composites increases with oxidation time. In the second stage, the oxidation rate becomes slower as result of formation of the dense protective layer. The oxidation rate of the NiAl/Al2O3 composites is lower than that of NiAl. In this study, the NiAl/Al2O3 composite prepared from 7 micrometer NiAl powder and pre-oxidized at 650℃/2h has the best oxidation resistance. On the other hand, for reducing the production cost, the syntheses NiAl/Al2O3 composites with cheaper Ni, Al and Al2O3 powders by the reactive sintering method are investigated in this study. The result shows that the shape and density of the reactive sintered NiAl/Al2O3 composite synthesized in 2 atm Ar atmosphere and in a heating rate 15℃/ min. to 1450℃ is better than that composites synthesized in vacuum and in a heating rate of 5℃/min. to 1400℃. However, the relative density of the best reactive-sintered NiAl/Al2O3 composites is only 89.8%, which makes the mechanical and the oxidation properties decrease.Key Words: NiAl, NiAl/Al2O3 composites, oxidation, synthesis
8
YANG, Shyh-Chyi, and 楊士奇. "High Temperature Mechanical Properties of NiAl/Al2O3 Composites." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/64590805629751039863.
Анотація:
碩士國立成功大學
材料科學(工程)學系
85
NiAl介金屬化合物具有高熔點、高楊氏係數、低密度及高抗氧化的特 性，使其在航太工業之高溫應用上，足以取代傳統的鎳基及鈦基超合金而 成為深具發展潛力的材料。但是，NiAl亦有室溫脆性及高溫強度不足的缺 點。為改善NiAl的性能，以往的研究中有以預先氧化法將Al2O3添加於 NiAl中，而提升了NiAl的室溫機械性質。甚至藉由控制NiAl基材的晶粒尺 寸，更進一步提升此NiAl/Al2O3複材的機械性質。為進一步瞭解此NiAl/ Al2O3複合材之高溫機械性質，本實驗吾人繼續採用預先氧化法，先調製 出NiAl/Al2O3粉末再將之熱壓燒結緻密後，分別以壓縮測試法及單邊缺口 誶法(SENB)檢討了NiAl/Al2O3複合燒結體的高溫壓縮強度與韌性。 實 驗結果顯示：含有16.5 vol%Al2O3之NiAl/Al2O3複合燒結體在600, 800及1000 K的0.2%應變量之壓縮應力值分別為867, 678及366 MPa，而僅 含微量3.4vol%Al2O3的試樣其相同測試條件下之壓縮應力值分別為621, 629, 304 MPa。即Al2O3含量愈多，其高溫壓縮強度愈強。由壓縮應力與 溫度關係圖可知：藉由夾頭速率的提升(由0.01 mm/min提升10倍至0.1mm/ min)或Al2O3含量的增加(由3.4vol%增至16.5vol%)，NiAl/Al2O3複合材的 脆韌轉換溫度(BDTT)提升了50~100 K。 利用SENB法以三點抗折方式量 測高溫破斷韌性的結果顯示：各試樣的破壞韌性值皆隨測試溫度之升高而 增加。NiAl /3.4 vol%Al2O3試樣在1000 K時具有本研究中最高的破壞韌 性值26.4 MPa.m1/2，而NiAl/16.5 vol%Al2O3試樣會因較多的Al2O3抑制 了NiAl的延展性，使其在1000 K時的破壞韌性值減為18.8 MPa.m1/2。 Nickel aluminide intermetallic compound (NiAl) has high melting point, high strength , low density and excellent oxidation properties. It is possible to substitute for traditional Ni-based and Ti-based superalloys and is considered as the most potential high temperature material for applications in aerospace industry. However, the major drawback of NiAl is a lack of room temperature ductility and low creep resistance. NiAl/Al2O3powders can be prepared by preoxidizing the NiAl powder. The mechanical properties of hot pressed NiAl/Al2O3 composites at room temperature is better than NiAl compound. By controlling the grain size of NiAl matrix, the mechanical properties of NiAl/Al2O3 composites were also enhanced. In this study the high temperature strength and toughness were investigated by compressive testing and SENB method. The results show the compressive strength of hot pressed NiAl/Al2O3 composites containing 16.5 vol% Al2O3 is 867, 678, 366 MPa at 0.2% compressive strain at 600, 800, 1000 K individually. The compressive strengthof samples without preoxidation is 621, 629, 304 MPa. The high temperature compressive strength increased with incressing the content of Al2O3. The brittle to ductile transition temperature of NiAl increased by increasing thecross head rate from 0.01 to 0.1 mm/min or the content of Al2O3 from 3.4 to 16.5 vol% Al2O3. All fracture toughness measurement were done in four point bending with SENB method from 600 ~1100 K. The results show that KIC values of all samplesincreased with testing temperature increased. The NiAl/3.4vol%Al2O3 compositesshow the maximum fracture toughness of 26.4 MPa．m1/2 at 1000 K in this study. However, the KIC value of NiAl/16.5vol% Al2O3 composites is only 18.8 MPa．m1/2.
9
Hsu, Hsin-Chung, and 許信忠. "Growth of C60 thin-film on Al2O3/NiAl(100) and Au-Pt bimetallic clusters on Al2O3/NiAl(100) exposed to methanol." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/53861004915873516283.
Анотація:
碩士國立中央大學
物理研究所
100
We present a scanning tunneling microscopy study of C60 films grown on Al2O3/NiAl(100) under ultrahigh vacuum conditions. The C60 islands formed on the crystalline Al2O3 have rectangular shapes whereas those on the amorphous area have irregular shapes, resembling those on NiAl(100). The long side of the C60 rectangular islands was along the direction of protrusions, which are along two directions ([001] and [010] of NiAl(100)) and perpendicular to each other.. Increasing the C60 coverage, layer-by-layer grown was found to dominate the growth. On the grown C60 films, the boundary defects caused by mismatch of C60 islands were identified. Annealing to 400 K, C60 film was still stable but became rougher; increasing the temperature to 500 K or higher, C60 film became unstable and a lot of C60 desorbed. The Au-Pt bimetallic clusters at varied coverages on Al2O3/NiAl(100) were exposed to methanol 1 L. The morphological change is not recognized. Annealing to the sample up to 170 K, coalescence and dissociation of the bimetallic clusters are not observed.
10
Gu, Don-Lin, and 古東林. "Microstructure and Mechanical Properties of the NiAl/Al2O3 composites." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/06479379492601697733.
Анотація:
碩士國立成功大學
材料科學及工程學系
87
The intermetallic compound NiAl has potentials as a high temperature structural material because of its high melting point, low density, and excellent oxidation resistance. However, some disadvantages of NiAl which needs solving are brittleness at room temperature and low creep resistance. To improve the mechanical properties of NiAl, adding second phase to from intermetallic matrix composites is a practicable direction . It has been reported on "Pre-Oxidation Method", which shows NiAl/Al2O3 composites have better room temperature mechanical properties than that of NiAl. So it is worth studying further. In this study, as received NiAl powder and oxidized NiAl/Al2O3 powder were dry ball milled for a long time, and then hot-pressed in vacuum. The effects of ball milling on the NiAl/Al2O3 composite powder and the microstructures and mechanical properties of the hot pressed NiAl/Al2O3 composites were investigated. The results of the experiment show that both as received NiAl powder and pre-oxidized NiAl/Al2O3 powder oxidizes, refines, and strains after ball milling , and their particle size distributions are bimodal distributions. α-Al2O3 disperses in the grain boundary and within the grain of the NiAl/Al2O3 composites. As the ball milling time increases, NiAl/Al2O3 composites show refinement of grain size and increase in the content of α-Al2O3. Fracture mode of NiAl/Al2O3 transforms from intergranular mode to transgraular mode as the content of α-Al2O3 increases, and it benefits to increase the room temperature mechanical properties of NiAl/Al2O3 composites.
Частини книг з теми "NiAl-Al2O3":
1
Hwang, C. S., T. J. Liu, and J. P. Shich. "Metal Oxidation Process : NiAl/Al2O3 Composites." In Multiphased Ceramic Materials, 87–97. Berlin, Heidelberg: Springer Berlin Heidelberg, 2004. http://dx.doi.org/10.1007/978-3-642-18752-0_10.
2
Hu, Weiping, Keyun Wen, Hao Chen, Stepan Kyrsta, and Günter Gottstein. "Untersuchungen zu chemischer Stabilität, Grenzflächenstruktur und Debonding-Verhalten der von kontinuierlichen Al2O3-Fasern verstärkten NiAl-Verbundwerkstoffe." In Verbundwerkstoffe, 153–58. Weinheim, FRG: Wiley-VCH Verlag GmbH & Co. KGaA, 2006. http://dx.doi.org/10.1002/9783527609017.ch23.
Тези доповідей конференцій з теми "NiAl-Al2O3":
1
Liu, Dawei, Tong Zhou, Yan Wang, and Jinping Suo. "Design, Optimization and Performance Testing of Self-Healing Tritium Permeation Barriers." In 2014 22nd International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/icone22-30678.
Анотація:
Tritium permeation barriers (TPBs) are essential to reduce the tritium permeation through blanket structural materials and cooling tubes. The pores and cracks are the most important problem of thermally sprayed TPBs. Irradiation swelling is another serious problem in NiAl which used as adhesive layer in traditional Al2O3 coatings. A self-healing coating TiC+mixture (TiC/Al2O3)+Al2O3 without NiAl had been designed and manufactured by our group. It can cure 90% porosity after a certain heat treatment under normal atmosphere. The adhesive strength is as good as the traditional coating NiAl+Al2O3. The thermal shock cycles were 300, 210 and 123 at 600°C, 700°C and 800°C respectively. On the basis, the self-healing treatment parameters were explored further, and a more effective and efficient treatment was found. Structural design and component design were also researched. The thermal shock results showed that the thicknesses of TiC layer and mixture (TiC/Al2O3) layer both had a significant effect while the Al2O3 layer hadn’t. The interface of TiC and mixture (TiC/Al2O3) was most easily damaged, so other proportion of TiC and Al2O3 was applied, and several kinds of new coatings were designed, manufactured and tested. A better coating has been found, and it will probably be a good candidate for TPBs in fusion reactors.
2
Afandi, N. F., A. Manap, S. N. A. Yusof, M. A. Salim, M. Al Azim, S. Z. Othman, N. I. M. Pauzi, Nooririnah Omar, and H. Misran. "Effect of calcination time on NiAl-Al2O3 using gel combustion synthesis method." In PROCEEDINGS OF THE 23RD SCIENTIFIC CONFERENCE OF MICROSCOPY SOCIETY MALAYSIA (SCMSM 2014). AIP Publishing LLC, 2015. http://dx.doi.org/10.1063/1.4919180.
3
Hearley, J. A., J. A. Little, and A. J. Sturgeon. "Oxidation Properties of NIAI Intermetallic Coatings Prepared by High Velocity Oxy-Fuel Thermal Spraying." In ITSC 1998, edited by Christian Coddet. ASM International, 1998. http://dx.doi.org/10.31399/asm.cp.itsc1998p0089.
Анотація:
Abstract A reaction-formed NiAl intermetallic compound (IMC) powder has been deposited as a coating onto low carbon steel test coupons by the High Velocity Oxy-Fuel (HVOF) process using both gaseous and liquid fuels. The microstructure of this coating has been examined using scanning electron microscopy and x-ray diffraction and was found to depend on spraying conditions. Oxidation tests on the coating in air, between the temperatures of 800°C-1200°C, revealed that an α-alumina (Al2O3) scale formed on the coating's surface. At 1200°C, a nickel spinel (NiO/NiAl2O4) and haematite (Fe2O3) phases were observed. Diffusion studies were performed to calculate an activation energy for iron ion diffusion in NiAl.
4
OLESZAK, D., and A. OLSZYNA. "CRYSTALLITE SIZE AND LATTICE STRAIN DETERMINATION OF NIAL-AL2O3 NANOCOMPOSITE OBTAINED BY REACTIVE MILLING." In Proceedings of the XIX Conference. WORLD SCIENTIFIC, 2004. http://dx.doi.org/10.1142/9789812702913_0008.
5
Page, Richard A., and Gerald R. Leverant. "Inhibition of Interdiffusion From MCrAlY Overlay Coatings by Application of a Ni-Re Interlayer." In ASME 1998 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/98-gt-375.
Анотація:
The durability of protective coatings on combustion turbine blades and vanes is a critical issue in the power generation industry. Coating life usually dictates the refurbishment intervals for these components, and these intervals have generally been of shorter duration than desired by the operators of the equipment. Both MCrAlY and aluminide type coatings protect against oxidation and hot corrosion by forming a protective Al2O3 surface layer. Degradation of the coatings occurs by depletion of the aluminum content of the coating through interdiffusion with the substrate and through the formation and spallation of an external Al2O3 scale. The results obtained in this study clearly show that the application of a thin interlayer of Ni-Re beneath the MCrAlY coating can significantly decrease the growth rate of the inner β-NiAl depletion zone. Order of magnitude reductions in the inner depletion zone thickness formed at 1000 hours were obtained with both the Ni-32 wt.% Re and the Ni-47 wt% Re interlayer coatings. Since formation of the inner depletion zone is believed to result from interdiffusion with the substrate, these results suggest that the Ni-Re interlayer provided a significant impediment to the inward diffusion of Al into the substrate.
6
Nylén, P., J. Wigren, J. Idetjärn, L. Pejryd, M. Friis, and P. Moretto. "On-Line Microstructure and Property Control of a Thermal Sprayed Abrasive Coating." In ITSC2001, edited by Christopher C. Berndt, Khiam A. Khor, and Erich F. Lugscheider. ASM International, 2001. http://dx.doi.org/10.31399/asm.cp.itsc2001p1213.
Анотація:
Abstract A process control tool has been developed for air plasma spraying of a NiAl (bond coat) and Al2O3 (top coat) coating systems. The process is employed at Volvo Aero Corporation for abrasive purposes, such as knife-edge applications on compressor parts. In-flight particle temperatures, velocities and diameters were measured by the DPV2000 system. Several samples were sprayed and the coating microstructures were evaluated using Image Analysis techniques on optical and scanning electron microscope images. Top and bond coat thickness, oxides, porosity, grit blast residues, delaminations, surface roughness (on top, bond and substrate) and tensile strength were evaluated. Statistical regression analysis was then used to establish relationships between process parameters (i.e. current and primary gas flow), particle in-flight characteristics (i.e. velocity and temperature), microstructure properties, and mechanical properties. The equations derived were finally used for development of a tool, which can be used by the operator for on-line monitoring and control of the coating characteristics based on information of the current particle inflight characteristics. The tool makes it possible to continuously adjust the process set points, ensuring a high reproducibility and stability of the process.