High-Temperature Properties of Silicon Nitride with Lu-Si-O-N Grain Boundary Phases

2006 ◽  
Vol 317-318 ◽  
pp. 425-428 ◽  
Author(s):  
Yoshinobu Yamamoto ◽  
Toshiyuki Nishimura ◽  
Naoto Hirosaki ◽  
S. Guo ◽  
J. Cao ◽  
...  
Keyword(s):  
Weight Gain ◽  
High Temperature ◽  
Silicon Nitride ◽  
Grain Boundary ◽  
Strain Curve ◽  
Secondary Phase ◽  
Silicon Oxynitride ◽  
Stress Strain Curve ◽  
High Temperature Properties ◽  
Nitride Ceramics

High-temperature properties of silicon nitride ceramics with Lu-silicon-oxynitride grain boundary phases were investigated. Si3N4 powder with 1.2 mol% (SN12) and 4.8 mol% (SN48) of Lu2O3 were gas-pressure hot-pressed at 1950°C for 2 h under 20 MPa in 1 MPa N2. SN12 consisted of elongated β-Si3N4 and a secondary phase, Lu4Si2O7N2, whilst SN48 consisted of elongated β-Si3N4 and Lu4Si2O7N2 + Lu2SiO5. At 1500°C and 1600°C, the stress-strain curve of SN48 was nonlinear, whilst that of SN12 was linear, indicating that SN12 broke as a brittle fracture at these temperatures. SN12 had excellent oxidation resistance and weight gain during the oxidation at 1500°C for 1000 h was 4 g/m2. Creep lifetime of SN12 at 1500°C under tensile stress of 137 MPa exceeded 1678.5 h.

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.

Joining of silicon nitride ceramics for high-temperature applications

2000 ◽  
Vol 15 (1) ◽  
pp. 136-141 ◽  
Author(s):  
Rong-Jun Xie ◽  
Mamoru Mitomo ◽  
Li-Ping Huang ◽  
Xi-Ren Fu
Keyword(s):  
High Temperature ◽  
Silicon Nitride ◽  
Grain Boundary ◽  
Bond Strength ◽  
Room Temperature ◽  
Hot Isostatic Pressing ◽  
Joint Zone ◽  
Nitride Ceramics ◽  
High Bond ◽  
High Bond Strength

A refractory silicon nitride joint, which contains β–Si3N4 grains and grain boundary amorphous phase in the joined layer, was developed with the aid of a ceramic adhesive based on the system Si3N4–Y2O3–SiO2–Al2O3. The similarity in chemistry and microstructure between the parent ceramic and the joint zone indicates that the joining mechanism is the same as that involved in the sintering of Si3N4. The resultant joint exhibits a high bond strength of 550 MPa at 25 °C and retains a strength of 332 MPa at 1000 °C. Post-joining hot-isostatic pressing was applied to strengthen the joint, resulting in increased strengths of 668 MPa at room temperature and 464 MPa at 1000 °C.

ChemInform Abstract: Dopant Distribution in Grain-Boundary Films in Calcia-Doped Silicon Nitride Ceramics.

ChemInform ◽  
2010 ◽  
Vol 30 (13) ◽  
pp. no-no
Author(s):  
Hui Gu ◽  
Xiaoqing Pan ◽  
Rowland M. Cannon ◽  
Manfred Ruehle
Keyword(s):  
Silicon Nitride ◽  
Grain Boundary ◽  
Dopant Distribution ◽  
Nitride Ceramics ◽  
Doped Silicon ◽  
Boundary Films

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

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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