3 edition of Hot-pressed silicon nitride with various lanthanide oxides as sintering additives found in the catalog.
Hot-pressed silicon nitride with various lanthanide oxides as sintering additives
|Statement||K. Ueno and Y. Toibana|
|Series||NASA technical memorandum -- 77424|
|Contributions||Toibana, Yasuo, United States. National Aeronautics and Space Administration, Leo Kanner Associates|
|The Physical Object|
ume friction of TiN (Tab. 1) and constant amount of sintering additives (6 wt.% of Al 2O3 and 4 wt.% of Y 2O3 count to the amount of Si 3N4) were hot pressed from the following com-mercially available powders: silicon nitride (SILICUM NI-TRIDE Si 3N4 GRADE M 11 HP, H.C. Starck GmbH), titanium nitride (TITANIUM NITRIDE TiN GRADE A H.C. Silicon nitride is usually deposited using one of the following silicon precursors: silane, dichlorosilane, trichlorosilane, or silicon tetrachloride. Model composite systems of monazite-coated fibers in hot pressed billets of alumina have shown very promising interfacial debonding induced by propagating cracks generated by Vickers.
A process for preparing a self-reinforced silicon nitride ceramic body of high fracture toughness comprising hot-pressing a powder mixture containing silicon nitride, a densification aid such as sodium oxide, a conversion aid such as lanthanum oxide and a compound, such as gallium oxide, which enhances growth of β-silicon nitride whiskers-under conditions such that densification and the in. The investigation of multi-component complex systems composed of oxides, nitrides, and carbides has intensified in the last few years. Phase Diagrams in Advanced Ceramics reviews some of the recent advances inthe understanding of these composite systems, providing insight into how phase diagrams can be utilized in the fabrication of whiskers and ceramic-matrix whisker-reinforced ceramics.
Comprehensive Hard Materials deals with the production, uses and properties of the carbides, nitrides and borides of these metals and those of titanium, as well as tools of ceramics, the superhard boron nitrides and diamond and related compounds. Under the auspices of the NATO Science Committee an Advanced Research Workshop (ARW) was held on the Physics and Chemistry of Carbides, Nitrides and Borides (University of Manchester, September, ) in order to assess progress to date and identify the most promising themes and materials for future research.
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Get this from a library. Hot-pressed silicon nitride with various lanthanide oxides as sintering additives.
[Kazuo Ueno; Yasuo Toibana; United States. National Aeronautics and Space Administration.; Leo Kanner Associates.]. the first commercial hot-pressed silicon nitride (HPSN) .
In the ’s, a full-scale effort to produce the ceramic gas turbine was initiated in the USA. The protective atmosphere suppresses the evaporation of silicon, nitrogen and additives, and enables the sintering reaction to take place. Higher temperatures ( - °C) and longer times (up to 5 hours) are needed than used to produce hot-pressed silicon nitride, and strengths approaching those of hot-pressed silicon nitride can be achieved.
The elastic moduli and fracture toughness of hot-pressed Si 3 N 4 ceramics, using, and wt.% of Lu 2 O 3 additives, were studied by means of ultrasonic measurements and Vickers indentation crack size measurements, respectively. The elastic moduli were found to increase with the amount of Lu 2 O 3 additive for silicon nitride which was not completely by: Hot-pressed silicon nitride with various lanthanide oxides as sintering additives Technical Report Ueno, K ; Toibana, Y The effects of addition of various lanthanide oxides and their mixture with Y2O3 on the sintering of Si3N4 were investigated.
Oxide additives (Al 2 O 3 1 Y 2 O 3 or RE 2 O 3) are mixed with silicon nitride powder and react at sintering temperatures of À C with silica present on the surface of the silicon. Silicon nitride is a chemical compound of the elements silicon and nitrogen. Si 3 N 4 is the most thermodynamically stable of the silicon nitrides.
Hence, Si 3 N 4 is the most commercially important of the silicon nitrides when referring to the term "silicon nitride". It is a white, high-melting-point solid that is relatively chemically inert, being attacked by dilute HF and hot H. Int. High Technology Ceramics 3 () High-Temperature Durability and Limits of Sintered and Hot-Pressed Silicon Nitride Materials U.
Ernstberger, G. Grathwohl and F. Thiimmler Institut fiir Werkstoffkunde II, Universit~it Karlsruhe, Institut fiir Material- und Festk6rperforschung, Kernforschungszentrum Karlsruhe, PostfachD Karlsruhe 1, FRG SUMMA R Y Hot.
The effect of water vapour on oxidation was studied with hot-pressed silicon nitride containing both yttria and alumina as sintering aids in wet air flow w 20, 30, and 40 vol% H 2 O at °C for h.
The oxidation kinetics were determined in a wet air flow with 20 vol% H 2 O and in a dry air flow at °C for oxidation times up to h. The water vapour in the atmosphere slightly. Silicon Nitride. Silicon nitride, like Silicon Carbide, is also available in two main types, reaction bonded and sintered.
Silicon nitride ceramics are electrical insulators and are resistant to attack by many molten metals. With low thermal conductivity and excellent thermal shock resistance, silicon nitride ceramics are used in many RF heating applications where the material is in contact.
The high temperature strength and oxidation behaviour of the hot-pressed ceramics were investigated and correlated with the cationic radii of the oxide additives. The flexural strength at °C increased, from MPa for Si3N4-La2Si2O7 to MPa for Si3N4-Sc2Si2O7 which is correlated with a decreasing cationic radius of the oxide additive.
tend to improve with the addition of rare-earth oxides to silicon nitride ceramics. A number of studies about the influence of rare-earth ox-ides as sintering aids of silicon nitride were performed in 80s, 90s and 00s. Among these, Sanders et al. investi-gated the effect of adding SiO 2 together with Y 2O 3, CeO 2, La 2O 3 or Sm 2O.
sition that is a function of the sintering aids used and the silica on the surface of the silicon nitride, acts as a “glue” to hold the BN platelets together. It is proposed that if the sintering aids are added in the appropriate proportion directly to the BN powder , as well.
Hot Pressed Silicon Nitride Material Properties Keywords: hot pressed silicon nitride, hpsn, density, Flexural strength, MOR, modulus of rupture, elastic modulus, youngs modulus, poissons ratio, hardness, maximum use temperature, thermal conductivity, CTE, coefficient of thermal expansion, material properties, physical properties Created Date.
Background. Hot pressing of Silicon Nitride produces a material of virtually zero porosity. This hard, grey ceramic is, however, still very lightweight.
Silicon Nitride shows good resistance to wear and abrasion. It shows very little oxidation at elevated. Hot pressing of Silicon Nitride produces a material of virtually zero porosity.
This hard, grey ceramic is, however, still very lightweight. Silicon Nitride shows good resistance to wear and abrasion. It shows very little oxidation at elevated temperatures, and high hardness and strength above C. Microstructure Development in Hot-Pressed Silicon Carbide: Effects of Aluminum, Boron, and Carbon Additives Xiao Feng Zhang1, Qing Yang2, Lutgard C.
De Jonghe1,2 1 Materials Sciences Division, Lawrence Berkeley National Laboratory, University of California, Berkeley, CA The influence of Lu2O3 on phase transformation and seeds morphology was investigated.
The result showed that the β-Si3N4 seeds with up to 95% β phase content could be obtained with 2wt% Lu2O3 as the additive content under °C for two hours. The microstructure and mechanical properties of hot-pressed Si3N4 ceramics, using 9wt.% of Lu2O3• additives were investigated by the means of MTS.
Acronym Definition; HPSN: Hot-Pressed Silicon Nitride: HPSN: High Performance Scalable Networking: HPSN: Human Patient Simulation Network (Medical Education Technologies, Inc.): HPSN: Hampshire Public Service Network (UK): HPSN.
Silicon nitride (SigN4) in both the pressure-sintered (hot pressed) and reaction-sintered forms offers a great potential for use in hot-flow-path components in gas *Associate Professor of Metallurgy, Cleveland State University, Cleveland, Ohio; Summer Faculty Fellow at the Lewis Research Center in.
non-oxide ceramics are silicon carbide SiC, silicon nitride Si3N4 and the so-called sialons, nitride-based ceramics with varying oxide contents. Non-oxides must undergo high-temperature processing in reducing or inert atmosphere to prevent oxidation. Furthermore, their strong and predominantly covalent (i.e.
directional) atomic bonds inhibit atomic.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.After firing, as for Hot Pressed Silicon Nitride, it can be diamond ground to tolerances as close as mm.
Although not as strong as Hot Pressed Silicon Nitride, its strength is held up to C, with long term oxidation resistance up to C. The thermal and electrical properties of the two forms of Silicon Nitride are however very similar.