Elevated-Temperature Creep of Silicon Carbide-Aluminum Nitride Ceramics: Role of Grain Size

Effect of adding up to 5wt% CaF2 on the densification and microstructural development of hot pressed aluminum nitride (AlN) was investigated. SEM investigation showed that the grain size of the sintered sample decreases with the increasing content of CaF2. Secondary-phase evolution paths converge from CA6 to CA phase above 1650°C. TEM micrographs showed that formed secondary phases could evaporate from sintered bodies at higher temperatures in the carbon-containing nitrogen atmosphere and the residuals were mainly distributed at triple grain junctions, keeping direct connections of AlN grains. Translucnet AlN ceramics were prepared using CaF2 additive sintered at 1850°C for 5 h.

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Role of the grain-boundary phase on the elevated-temperature strength, toughness, fatigue and creep resistance of silicon carbide sintered with Al, B and C

Acta Materialia ◽

10.1016/s1359-6454(00)00246-9 ◽

2000 ◽

Vol 48 (18-19) ◽

pp. 4599-4608 ◽

Cited By ~ 80

Author(s):

D Chen ◽

M.E Sixta ◽

X.F Zhang ◽

L.C De Jonghe ◽

R.O Ritchie

Keyword(s):

Silicon Carbide ◽

Elevated Temperature ◽

Grain Boundary ◽

Creep Resistance ◽

Boundary Phase ◽

Elevated Temperature Strength

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The role of CaO additive on sintering of aluminum nitride ceramics

Ceramics International ◽

10.1016/j.ceramint.2017.09.104 ◽

2017 ◽

Vol 43 (18) ◽

pp. 16972-16979 ◽

Cited By ~ 14

Author(s):

A.L. Molisani ◽

H. Goldenstein ◽

H.N. Yoshimura

Keyword(s):

Aluminum Nitride ◽

Nitride Ceramics

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CBED analysis of impurity distributions in AlN

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100174205 ◽

1990 ◽

Vol 48 (4) ◽

pp. 214-215

Author(s):

Daniel Callahan ◽

G. Thomas

Keyword(s):

Aluminum Nitride ◽

Bulk Material ◽

Strong Dependence ◽

Lattice Parameter ◽

Promising Technique ◽

Nitride Ceramics ◽

Surface Phases ◽

Convergent Beam ◽

Oxygen Impurities

Oxygen impurities may significantly influence the properties of nitride ceramics with a strong dependence on the microstructural distribution of the impurity. For example, amorphous oxygen-rich grain boundary phases are well-known to cause high-temperature mechanical strength degradation in silicon nitride whereas solutionized oxygen is known to decrease the thermal conductivity of aluminum nitride. Microanalytical characterization of these impurities by spectral methods in the AEM is complicated by reactions which form oxygen-rich surface phases not representative of the bulk material. Furthermore, the impurity concentrations found in higher quality ceramics may be too low to measure by EDS or PEELS. Consequently an alternate method for the characterization of impurities in these ceramics has been investigated.Convergent beam electron diffraction (CBED) is a promising technique for the study of impurity distributions in aluminum nitride ceramics. Oxygen is known to enter into stoichiometric solutions with AIN with a consequent decrease in lattice parameter.

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High thermal conductivity of pure dense SiC ceramics prepared via HTPVT

Functional Materials Letters ◽

10.1142/s1793604719500322 ◽

2019 ◽

Vol 12 (03) ◽

pp. 1950032 ◽

Cited By ~ 2

Author(s):

Yuchen Deng ◽

Yaming Zhang ◽

Nanlong Zhang ◽

Qiang Zhi ◽

Bo Wang ◽

...

Keyword(s):

Thermal Conductivity ◽

Silicon Carbide ◽

Grain Size ◽

Phase Composition ◽

Room Temperature ◽

Vapor Transport ◽

Physical Vapor Transport ◽

Growth Substrate ◽

Sic Ceramics ◽

Evolution Of Microstructure

Pure dense silicon carbide (SiC) ceramics were obtained via the high-temperature physical vapor transport (HTPVT) method using graphite paper as the growth substrate. The phase composition, the evolution of microstructure, the thermal diffusivity and thermal conductivity at RT to 200∘C were investigated. The obtained samples had a relative density of higher than 98.7% and a large grain size of 1[Formula: see text]mm, the samples also had a room-temperature thermal conductivity of [Formula: see text] and with the temperature increased to 200∘C, the thermal conductivity still maintained at [Formula: see text].

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