scholarly journals Crack Healing Behaviour and High Temperature Strength of Silicon Nitride Ceramics.

1999 ◽  
Vol 65 (633) ◽  
pp. 1132-1139 ◽  
Author(s):  
Kotoji ANDO ◽  
MinCheol CHU ◽  
Yasuyoshi KOBAYASHI ◽  
Feiyuan YAO ◽  
Shigemi SATO
Keyword(s):  
High Temperature ◽  
Silicon Nitride ◽  
High Temperature Strength ◽  
Crack Healing ◽  
Nitride Ceramics

Properties of In Situ Reinforced Silicon Nitride Ceramics

1991 ◽  
Vol 251 ◽  
Author(s):  
C.-W. Li ◽  
J. Yamanis ◽  
P.J. Whalen ◽  
C.J. Gasdaska ◽  
C.P. Ballard
Keyword(s):  
High Temperature ◽  
Silicon Nitride ◽  
Metastable Phase ◽  
Abrasive Particle ◽  
Ceramic Matrix Composites ◽  
Ceramic Composites ◽  
High Fracture Toughness ◽  
High Temperature Strength ◽  
Nitride Ceramics

ABSTRACTIn situ reinforced (ISR) silicon nitride ceramics have been developed to have microstructures that mimic the best whisker containing ceramic matrix composites. Large, interlocking needle-like grains of beta silicon nitride can be produced throughout these materials to create an isotropic, high-temperature ceramic with high fracture toughness (˜9 MPa√m), good high-temperature strength (4 Pt MOR = 750 MPa at 25°C and 500 MPa at 1375°C), high Weibull modulus (m >20), and low creep at high temperature. Since these materials do not rely on transforming metastable phase inclusions as a toughening mechanism, their fracture resistance is virtually insensitive to temperature. The high crack growth resistance of these ceramics also yields a material which is extremely defect tolerant. Residual MOR strengths of 300–400 MPa are typical after multiple 50-kg Vicker's indentations of the sample tensile surface. After abrasive particle impact, the biaxial strengths of the in situ reinforced ceramics are typically more than twice that of traditional, fine-grained silicon nitrides.Unlike ceramic composites toughened using whisker additives, the in situ reinforcement approach to silicon nitride development does not require the use of complicated whisker dispersion techniques for green processing, nor is shape-limiting hot pressing required for densification during sintering.

High temperature strength of silicon nitride ceramics with ytterbium silicon oxynitride

1997 ◽  
Vol 12 (1) ◽  
pp. 203-209 ◽  
Author(s):  
Toshiyuki Nishimura ◽  
Mamoru Mitomo ◽  
Hisayuki Suematsu
Keyword(s):  
High Temperature ◽  
Silicon Nitride ◽  
Bending Strength ◽  
High Strength ◽  
Secondary Phase ◽  
Silicon Oxynitride ◽  
High Temperature Strength ◽  
High Melting Point ◽  
Powder Mixtures ◽  
Nitride Ceramics

Silicon nitride ceramics with ytterbium silicon oxynitride (Yb4Si2O7N2) as secondary phase were fabricated by hot-pressing the powder mixtures, including 50.0 to 97.0 mol% of silicon nitride with a mixture of Yb2O3 and SiO2 (Yb2O3/SiO2 = 4). Sinterability of the materials with Yb2O3 was higher than that with Y2O3 in the same composition of raw powder mixtures. High density materials were obtained under the condition of 50.0 to 89.1 mol% of silicon nitride in raw powder mixtures. Mechanical properties of silicon nitride containing 97.6 mol% of Si3N4 and 2.4 mol% of Yb4Si2O7N2 were measured. Fracture toughness measured by the indentation technique was 5.9 MPam1/2. Bending strength at room temperature and at 1500 °C was 977 MPa and 484 MPa, respectively. The silicon nitride grains consisted of highly elongated rod-like grains and thin needle-like grains. The Yb4Si2O7N2 grains were crystallized at multigrain junctions and bonded close to Si3N4 grains. High strength at high temperature is supposed to be based on the presence of crystalline Yb4Si2O7N2 having a high melting point.

Microstructural characterization and high-temperature strength of hot-pressed silicon nitride ceramics with Lu2O3additives

2003 ◽  
Vol 83 (6) ◽  
pp. 357-365 ◽  
Author(s):  
Shuqi Guo ◽  
Naoto Hirosaki ◽  
Yoshinobu Yamamoto ◽  
Toshiyuki Nishimura ◽  
Yoshizo Kitami ◽  
...  
Keyword(s):  
High Temperature ◽  
Silicon Nitride ◽  
Microstructural Characterization ◽  
High Temperature Strength ◽  
Nitride Ceramics

Lattice Imaging of Grain Boundaries in Ceramics

1977 ◽  
Vol 35 ◽  
pp. 114-115
Author(s):  
D. R. Clarke ◽  
G. Thomas
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Silicon Nitride ◽  
Grain Boundaries ◽  
High Temperature Strength ◽  
Current Interest ◽  
Lattice Imaging ◽  
Special Significance ◽  
Structural Applications ◽  
Refractory Ceramics

Grain boundaries have long held a special significance to ceramicists. In part, this has been because it has been impossible until now to actually observe the boundaries themselves. Just as important, however, is the fact that the grain boundaries and their environs have a determing influence on both the mechanisms by which powder compaction occurs during fabrication, and on the overall mechanical properties of the material. One area where the grain boundary plays a particularly important role is in the high temperature strength of hot-pressed ceramics. This is a subject of current interest as extensive efforts are being made to develop ceramics, such as silicon nitride alloys, for high temperature structural applications. In this presentation we describe how the techniques of lattice fringe imaging have made it possible to study the grain boundaries in a number of refractory ceramics, and illustrate some of the findings.

Electron Microscopy of Silicon Nitride-Based Ceramics

1991 ◽  
Vol 49 ◽  
pp. 926-927
Author(s):  
Gareth Thomas
Keyword(s):  
Electron Microscopy ◽  
High Temperature ◽  
Silicon Nitride ◽  
World Wide ◽  
Sintering Temperature ◽  
Liquid Phase Sintering ◽  
High Temperature Strength ◽  
Sintering Additives ◽  
Glass Forming ◽  
Dense Product

Silicon nitride and silicon nitride based-ceramics are now well known for their potential as hightemperature structural materials, e.g. in engines. However, as is the case for many ceramics, in order to produce a dense product, sintering additives are utilized which allow liquid-phase sintering to occur; but upon cooling from the sintering temperature residual intergranular phases are formed which can be deleterious to high-temperature strength and oxidation resistance, especially if these phases are nonviscous glasses. Many oxide sintering additives have been utilized in processing attempts world-wide to produce dense creep resistant components using Si3N4 but the problem of controlling intergranular phases requires an understanding of the glass forming and subsequent glass-crystalline transformations that can occur at the grain boundaries.

Crack healing behaviour and high-temperature strength of mullite/SiC composite ceramics

2002 ◽  
Vol 22 (8) ◽  
pp. 1313-1319 ◽  
Author(s):  
Kotoji Ando ◽  
Min-Cheol Chu ◽  
Kiichi Tsuji ◽  
Toshikazu Hirasawa ◽  
Yasuyoshi Kobayashi ◽  
...  
Keyword(s):  
High Temperature ◽  
High Temperature Strength ◽  
Crack Healing ◽  
Composite Ceramics

High temperature strength and fractography of sintered silicon nitride

1991 ◽  
Vol 17 (6) ◽  
pp. 335-341 ◽  
Author(s):  
A.K. Mukhopadhyay ◽  
S.K. Datta ◽  
D. Chakraborty
Keyword(s):  
High Temperature ◽  
Silicon Nitride ◽  
High Temperature Strength ◽  
Sintered Silicon

Effect of β-Si3N4 Powder on Thermal Conductivity of Silicon Nitride Ceramics

2015 ◽  
Vol 655 ◽  
pp. 11-16 ◽  
Author(s):  
Xing Li Liu ◽  
Meng Meng Peng ◽  
Xiao Shan Ning ◽  
Yosuke Takahashi
Keyword(s):  
Thermal Conductivity ◽  
Heat Treatment ◽  
High Temperature ◽  
Silicon Nitride ◽  
High Temperature Heat Treatment ◽  
Plasma Sintering ◽  
Nitride Ceramics ◽  
Temperature Heat ◽  
Spark Plasma ◽  
Temperature Heat Treatment

To investigate the influence of β-Si3N4 powder on thermal conductivity of silicon nitride, coarse, fine β-Si3N4 powder and various β-Si3N4/α-Si3N4 ratios of starting powders were adopted to fabricate ceramics by spark plasma sintering at 1600°Cand subsequent high-temperature heat treatment at 1900°C with the sintering additives of Y2O3 and MgO. It is found that with more fine β-Si3N4 powder in the starting powder, β-Si3N4 grains exhibit high thermal conductivity, which is partly resulted from the compaction of β-Si3N4 grains.

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