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

Contact damage resistances of silicon nitride ceramics with various grain boundary phases are investigated in this study. The grain boundary phases are controlled by the addition of different types of sintering additives, or the crystallization of intergranular phase in a silicon nitride. We control the microstructures of materials to have similar grain sizes and the same phases to each other. Contact testing with spherical indenters is used to characterize the damage response. The implication is that the grain boundary phase can be another controllable factor against contact damage and strength degradation even though it is not critical relative to the effect of grain morphology.

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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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Contact Damage and Strength Degradation in Nitrided Pressureless Sintered (NPS) Silicon Nitrided Ceramics

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.353-358.102 ◽

2007 ◽

Vol 353-358 ◽

pp. 102-105

Author(s):

Chang Gyu Kang ◽

Chul Kim ◽

Tae Woo Kim ◽

In Sub Han ◽

Kee Sung Lee

Keyword(s):

Silicon Nitride ◽

Cost Effective ◽

Strength Degradation ◽

Pressureless Sintering ◽

Contact Damage ◽

Damage Resistance ◽

Plastic Damage ◽

Nitride Ceramics ◽

Damage Response ◽

Bend Tests

A study is made of the damage resistance and strength degradation of nitrided pressureless sintered (NPS) silicon nitride ceramics. The silicon nitride is prepared by cost-effective NPS process combining by nitridation and consecutive pressureless sintering. Contact testing with spherical indenters is used to characterize the damage response. Examination of the indentation sites indicates a quasi-plastic damage modes are observed. Bend tests on specimens containing quasi-plastic contact damages reveal those materials to be not susceptible to strength degradation.

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Effect of Oxynitride Grain Boundary Phase on Toughening of Silicon Nitride Ceramics

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.317-318.649 ◽

2006 ◽

Vol 317-318 ◽

pp. 649-652 ◽

Cited By ~ 1

Author(s):

Takafumi Kusunose ◽

Tohru Sekino ◽

P.E.D. Mogan ◽

Koichi Niihara

Keyword(s):

Fracture Toughness ◽

Silicon Nitride ◽

Grain Boundary ◽

Crack Propagation ◽

Hot Pressing ◽

Boundary Phase ◽

Toughening Mechanism ◽

Nitride Ceramics

The Si3N4/YSiO2N composite in which crystalline YSiO2N was formed as grain boundary phase was fabricated by hot-pressing the mixture of SiO2, Si3N4 and Y2O3. The fracture toughness of this composite was significantly improved, compared to the Si3N4 composites containing Y5Si3O12N or Y2Si3O3N4 as a grain boundary phases. To clarify the toughening mechanism, the microstructure and the crack propagation profiles were observed.

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The effect of grain boundary phase on contact damage resistance of alumina ceramics

Journal of Materials Science ◽

10.1023/b:jmsc.0000047547.09325.3d ◽

2004 ◽

Vol 39 (23) ◽

pp. 7023-7030 ◽

Cited By ~ 3

Author(s):

Jae Hun Kim ◽

Shiwoo Lee ◽

Kee Sung Lee ◽

Do Kyung Kim

Keyword(s):

Grain Boundary ◽

Boundary Phase ◽

Alumina Ceramics ◽

Contact Damage ◽

Damage Resistance

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Aspects of Stability of Amorphous Grain Boundary Phase in Silicon Nitride Ceramics

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.89-91.361 ◽

1993 ◽

Vol 89-91 ◽

pp. 361-366 ◽

Cited By ~ 1

Author(s):

A.K. Jha ◽

Se Joong Yoon

Keyword(s):

Silicon Nitride ◽

Grain Boundary ◽

Boundary Phase ◽

Nitride Ceramics

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Examination of Fracture Interfaces in Silicon Nitride

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100113925 ◽

1975 ◽

Vol 33 ◽

pp. 60-61

Author(s):

Nancy J. Tighe

Keyword(s):

Silicon Nitride ◽

Grain Boundary ◽

Crack Growth ◽

Subcritical Crack Growth ◽

Slow Crack Growth ◽

Ceramic Materials ◽

Grain Boundary Sliding ◽

Boundary Phase ◽

Turbine Engines ◽

Boundary Sliding

Silicon nitride is one of the ceramic materials being considered for the components in gas turbine engines which will be exposed to temperatures of 1000 to 1400°C. Test specimens from hot-pressed billets exhibit flexural strengths of approximately 50 MN/m2 at 1000°C. However, the strength degrades rapidly to less than 20 MN/m2 at 1400°C. The strength degradition is attributed to subcritical crack growth phenomena evidenced by a stress rate dependence of the flexural strength and the stress intensity factor. This phenomena is termed slow crack growth and is associated with the onset of plastic deformation at the crack tip. Lange attributed the subcritical crack growth tb a glassy silicate grain boundary phase which decreased in viscosity with increased temperature and permitted a form of grain boundary sliding to occur.

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Effect of rare-earth species on the wear properties of α sialon and β silicon nitride ceramics under tribochemical type conditions

Journal of Materials Research ◽

10.1557/jmr.2004.0357 ◽

2004 ◽

Vol 19 (9) ◽

pp. 2750-2758 ◽

Cited By ~ 6

Author(s):

Mark I. Jones ◽

Kiyoshi Hirao ◽

Hideki Hyuga ◽

Yukihiko Yamauchi

Keyword(s):

Rare Earth ◽

Grain Boundary ◽

Wear Behavior ◽

Rare Earth Oxide ◽

Lower Amount ◽

Boundary Phase ◽

Wear Properties ◽

Sintering Additives ◽

Nitride Ceramics ◽

Worn Surfaces

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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