Effect of grain boundary phase on the thermal conductivity of aluminium nitride ceramics

The wear properties under low loads of β Si3N4 and α sialon materials sintered with different rare-earth oxide sintering additives have been studied under dry sliding conditions using block-on-ring wear tests. All the worn surfaces showed an absence of fracture and smooth surfaces with the presence of an oxygen-rich filmlike debris indicating tribochemically induced oxidation of the surfaces. Extensive grain boundary removal was observed on the worn surfaces thought to be due to adhesion between this silicate phase and the tribochemically oxidized surfaces. The resistance to such oxidation and the properties of the residual grain boundary phase are thought to be important parameters affecting the wear behavior under the present testing conditions. For both the β Si3N4 and α sialon materials, there was an increase in wear resistance with decreasing cationic radius of the rare earth, thought to be due to improved oxidation resistance, and this was more remarkable in the case of the sialon materials where the incorporation of the sintering additives into the Si3N4 structure results in a lower amount of residual boundary phase.

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Aluminium nitride ceramics with high thermal conductivity from gas-phase synthesized powders

Journal of the European Ceramic Society ◽

10.1016/0955-2219(94)90031-0 ◽

1994 ◽

Vol 13 (3) ◽

pp. 229-237 ◽

Cited By ~ 33

Author(s):

Peter Greil ◽

Michael Kulig ◽

Dachamir Hotza ◽

Horst Lange ◽

Robert Tischtau

Keyword(s):

Thermal Conductivity ◽

Gas Phase ◽

Aluminium Nitride ◽

High Thermal Conductivity ◽

Nitride Ceramics

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Silicon Nitride Ceramics with Sodium Ion Conductive Grain Boundary Phase

Journal of Materials Research ◽

10.1557/jmr.2003.0383 ◽

2003 ◽

Vol 18 (12) ◽

pp. 2752-2755 ◽

Cited By ~ 13

Author(s):

Hirokazu Kawaoka ◽

Tohru Sekino ◽

Takafumi Kusunose ◽

Koichi Niihara

Keyword(s):

Electrical Conductivity ◽

Silicon Nitride ◽

Ionic Conductivity ◽

Grain Boundary ◽

Sodium Ion ◽

Boundary Phase ◽

Structural Ceramics ◽

Silicon Nitride Ceramic ◽

Nitride Ceramics ◽

Conductive Particles

Sodium ion-conductive silicon nitride ceramic with Na2O–Al2O3–SiO2 glass as the grain boundary phase was fabricated by adding Na2CO3, Al2O3, and SiO2 as sintering additives. The electrical conductivity was two and four orders of magnitude higher than that of Si3N4 ceramic with Y2O3 and Al2O3 additives at 100 and 1000°C, respectively. This result clearly indicates that ionic conductivity can be provided to insulating structural ceramics by modification of the grain boundary phase without dispersion of conductive particles.

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Microstructure and microanalysis of silicon nitride ceramics in the Y-Si-Al-O-N and Y-Si-O-N systems

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100178495 ◽

1990 ◽

Vol 48 (4) ◽

pp. 1072-1073

Author(s):

Michael K. Cinibulk

Keyword(s):

Silicon Nitride ◽

Grain Boundary ◽

Grain Boundary Sliding ◽

Liquid Phase Sintering ◽

Boundary Phase ◽

Full Density ◽

High Temperature Strength ◽

Transmission Electron ◽

Structural Applications ◽

Nitride Ceramics

Silicon nitride ceramics are among the leading candidate materials for use in structural applications at high temperatures. Due to the highly covalent nature of the Si-N bond and therefore low self-diffusivity, processing Si3N4 to full density requires the use of additives to provide a medium for liquid-phase sintering. When exposed to temperatures above ∼1000°C the resulting amorphous grain-boundary phases soften, leading to grain-boundary sliding and the eventual failure of the ceramic. The objectives of this work were to modify the grain-boundary phase composition and then attempt to devitrify the resulting intergranular phase to a refractory crystalline phase, producing a sintered Si3N4 with improved high-temperature strength and oxidation resistance. Transmission electron microscopy (TEM) and energy-dispersive x-ray spectroscopy (EDS) were used to characterize these materials. This paper describes these results.

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Effect of Grain Boundary Phase on Contact Damage Resistance of Silicon Nitride Ceramics

Key Engineering Materials - Advanced Si-Based Ceramics and Composites ◽

10.4028/0-87849-965-2.421 ◽

2005 ◽

pp. 421-426 ◽

Cited By ~ 1

Author(s):

Chul Seung Lee ◽

Kee Sung Lee ◽

Shi Woo Lee ◽

Do Kyung Kim

Keyword(s):

Silicon Nitride ◽

Grain Boundary ◽

Boundary Phase ◽

Contact Damage ◽

Damage Resistance ◽

Nitride Ceramics

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Effect of oxygen on the thermal conductivity of aluminium nitride ceramics

Journal of the European Ceramic Society ◽

10.1016/s0955-2219(97)00078-2 ◽

1997 ◽

Vol 17 (15-16) ◽

pp. 1891-1895 ◽

Cited By ~ 47

Author(s):

J. Jarrige ◽

J.P. Lecompte ◽

J. Mullot ◽

G. Müller

Keyword(s):

Thermal Conductivity ◽

Aluminium Nitride ◽

Nitride Ceramics ◽

Effect Of Oxygen

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Fabrication of Silicon Nitride Ceramics with Electrical Conductivity

Materials Science Forum ◽

10.4028/www.scientific.net/msf.486-487.501 ◽

2005 ◽

Vol 486-487 ◽

pp. 501-505 ◽

Cited By ~ 2

Author(s):

Yoon Ho Kim ◽

Tohru Sekino ◽

Hirokazu Kawaoka ◽

Takafumi Kusunose ◽

Tadachika Nakayama ◽

...

Keyword(s):

Mechanical Properties ◽

Electrical Conductivity ◽

Grain Boundary ◽

Room Temperature ◽

Boundary Phase ◽

Si3n4 Ceramic ◽

Nitride Ceramics ◽

Infinite Network ◽

Fine Microstructure ◽

Si3n4 Ceramics

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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