Effect of the Sintering Additives on the Microstructure and the Properties of Textured Silicon Nitride

2005 ◽  
pp. 242-246
Author(s):  
Dong Soo Park ◽  
Y.M. Kim ◽  
Byung Dong Hahn ◽  
Chan Park
Keyword(s):  
Silicon Nitride ◽  
Sintering Additives

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.

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.

scholarly journals Synthesis of "in situ" reinforced silicon nitride composites

2004 ◽  
Vol 69 (1) ◽  
pp. 59-67 ◽  
Author(s):  
Aleksandra Vuckovic ◽  
Snezana Boskovic ◽  
Ljiljana Zivkovic
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Silicon Nitride ◽  
Pressureless Sintering ◽  
Sintering Additives ◽  
Sintering Time

The objective of this work was to investigate the effect of two different sintering additives (CeO2 and Y2O3 + Al2O3), sintering time and amount of ?-Si3N4 seeds on the densification, mechanical properties and microstructure of self-reinforced Si3N4 based composites obtained by pressureless sintering. Preparation of ?-Si3N4 seeds, also obtained by a pressureless sintering procedure, is described. Samples without seeds were prepared for comparison. The results imply that self-reinforced silicon nitride based composites with densities close to the theoretical values and with fracture toughness of 9.3MPa m1/2 can be obtained using a presureless sintering procedure.

Development of High Performance Silicon Nitride Ceramics and their Applications

1992 ◽  
Vol 287 ◽  
Author(s):  
Yo Tajima
Keyword(s):  
Mechanical Properties ◽  
Silicon Nitride ◽  
High Performance ◽  
Future Prospect ◽  
Cutting Tools ◽  
Sintering Process ◽  
Sintering Additives ◽  
Nitride Ceramics ◽  
Engine Components

ABSTRACTProgress in sintering process and improvement of mechanical properties of silicon nitride ceramics are reviewed. Emphases are placed on contributions of advanced sintering techniques and better understanding of sintering additives and microstructure-properties relations. Current applications as engine components and cutting tools are described, and future prospect is considered.

Effect of the Sintering Additives on the Microstructure and the Properties of Textured Silicon Nitride

2005 ◽  
Vol 287 ◽  
pp. 242-246
Author(s):  
Dong Soo Park ◽  
Y.M. Kim ◽  
Byung Dong Hahn ◽  
Chan Park
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Silicon Nitride ◽  
Flexural Strength ◽  
Room Temperature ◽  
Sintering Additives ◽  
Significant Difference ◽  
Grain Width

Silicon nitride samples without and with 3 wt% of the aligned b-silicon nitride whisker seeds were prepared with 8.2 wt% Er2O3 and 1.9 wt% AlN. After sintering at 2148 K for 4h, the samples exhibited densities higher than 99.5% TD. The microstructures and properties of the samples were compared with those of the samples sintered with 4.8 wt% Y2O3 and 2.2 wt% Al2O3 at 2273 K for 4h. For samples without the whiskers, the sample with 4.8 wt% Y2O3 + 2.2 wt% Al2O3 had coarser microstructures than those with with 8.2 wt% Er2O3 + 1.9 wt% AlN. However, the samples with the whisker seeds, the former sample appeared to have only slightly larger grains than the latter sample in spite of the significant difference in the sintering temperatures. For the samples without the whisker seeds, the room temperature flexural strength was higher for the sample with Er2O3 + AlN. However, for the samples with the aligned whisker seeds, the sample with Y2O3 + Al2O3 exhibited higher room temperature flexural strength than that with Er2O3 + AlN although the average grain width of the former sample was larger than that of the latter sample. In case of the high temperature flexural strength at 1673 K, the flexural strengths of the samples with the whisker seeds were higher than double the strengths of the samples without the whisker seeds. For samples without the whisker seeds, the sample with Er2O3 + AlN exhibited better mechanical properties than that with Y2O3 + Al2O3. However, for the samples with the aligned whisker seeds, the sample with Y2O3 + Al2O3 exhibited better mechanical properties than those with Er2O3 + AlN. The results were explained in terms of the microstructures of the samples.

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