Effect of sintering temperature on microstructure and mechanical properties of highly porous silicon nitride ceramics produced by freeze casting

2010 ◽  
Vol 527 (24-25) ◽  
pp. 6501-6504 ◽  
Author(s):  
Feng Ye ◽  
Jingyi Zhang ◽  
Haijiao Zhang ◽  
Limeng Liu
Keyword(s):  
Mechanical Properties ◽  
Silicon Nitride ◽  
Porous Silicon ◽  
Sintering Temperature ◽  
Freeze Casting ◽  
Microstructure And Mechanical Properties ◽  
Nitride Ceramics ◽  
Highly Porous

Effects of Sintering Additives on the Microstructure and Mechanical Properties of Silicon Nitride Ceramics by GPS

2010 ◽  
Vol 105-106 ◽  
pp. 27-30 ◽  
Author(s):  
Wei Ru Zhang ◽  
Feng Sun ◽  
Ting Yan Tian ◽  
Xiang Hong Teng ◽  
Min Chao Ru ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Phase Transformation ◽  
Silicon Nitride ◽  
Porous Silicon ◽  
Flexural Strength ◽  
Relative Density ◽  
Sintering Additives ◽  
Microstructure And Mechanical Properties ◽  
Nitride Ceramics

Silicon nitride ceramics were prepared by gas pressure sintering (GPS) with different sintering additives, including La2O3, Sm2O3 and Al2O3. Effect of sintering additives on the phase-transformation, microstructure and mechanical properties of porous silicon nitride ceramics was investigated. The results show that the reaction of sintering additives each other and with SiO2 had key effects on the phase-transformation, grain growing and grain boundaries. With 9MPa N2 atmosphere pressure, holding 1h at 1850°C, adding 10wt% one of the La2O3, Sm2O3, Al2O3, porous silicon nitride was prepared and the relative density was 78%, 72%, 85% respectively. The flexural strength was less than 500MPa, and the fracture toughness was less than 4.8MPam1/2. Dropping compounds sintering additives, such as La2O3+Al2O3, Sm2O3+Al2O3 effectively improves the sintering and mechanical properties. The relative density was 99.2% and 98.7% with 10wt% compounds sintering additives. The grain ratio of length to diameter was up to 1:8. The flexural strength was more than 900MPa, and the fracture toughness was more than 8.9MPam1/2.

Fabrication of High-Porosity Silicon Nitride Ceramics with Excellent Mechanical Properties

2011 ◽  
Vol 284-286 ◽  
pp. 1339-1342
Author(s):  
Shao Yun Shan ◽  
Qing Ming Jia ◽  
Ya Ming Wang ◽  
Jin Hui Peng
Keyword(s):  
Mechanical Properties ◽  
Silicon Nitride ◽  
Porous Silicon ◽  
Aspect Ratio ◽  
High Aspect Ratio ◽  
High Strength ◽  
High Porosity ◽  
Microstructure And Mechanical Properties ◽  
Nitride Ceramics ◽  
Sintering Conditions

High-porosity silicon nitride ceramics with excellent mechanical properties were fabricated by the carbothermal reduction of SiO2. The influences of sintering conditions on microstructure and mechanical properties were studied. The results showed that microstructure and mechanical properties of porous silicon nitride ceramics were dependent mostly on the sintering conditions. The sintered porous silicon nitride ceramics exhibited the formation of fibrous microstructure with submicrometer-sized, high-aspect ratio b-Si3N4 grains, and uniform pore structure. Porous Si3N4 ceramics with a porosity of about 70%, and a flexural strength of about 70 MPa were obtained by sintering at 1750°C, with lower rate of temperature rise and no retaining time. The high strength was attributed to fine, high-aspect ratio b-Si3N4 grains and uniform pores between grains.

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