Silicon nitride tensile strength

Properties. Properties of structural silicon nitride ceramics are given in Table 2. These values represent available, well-tested materials. However, test methodology7 and the quality of the specimens, particularly7 their surface finish, can affect the measured values. Another important material property is tensile strength. Values obtained on Norton s NT154 material are 750 MPa at RT, 500 MPa at 1200°C, and 350 MPa (50,000 psi) at 1400°C (62). 

The tensile fracture strengths of three different structural ceramics are listed below hot-pressed silicon nitride (HPSN), reaction-bonded silicon nitride (RBSN), and chemical vapor-deposited silicon carbide (CVDSC), measured at room temperature. 

FIGURE 3. Variation of room temperature tensile strength with tested volume for 1-D SiC/RBSN containing -24 vol% fibers and hot-pressed silicon nitride [8, 15]. 

Funayama, M. Arai, Y. Tashiro, H. Aoki, T. Suzuki, K. Tamura, H. Kaya, H. Nishli and T. Isoda, Tensile strength of silicon nitride fibers produced from perhydropolysilazane, Nippon Seramikkusu Kyokai Gakujutsu Ronbushi. 98 [1], 104-107 (1990). 

L. Chuck, S. M. Goodrich, N. L. Hecht, and D. E. McCullum High-Temperature Tensile Strength and Tensile Stress Rupture Behavior of Norton/TRW NT-154 Silicon Nitride, Proceedings of the 14th Annual Conference on Composites and Advanced Ceramic Materials, Cocoa Beach, FL, January 1990. Published by the American Ceramic Society. 

Figure 14.5 Tensile strength of silicon-carbide and silicon-nitride fibers before and after exposure to high temperature. I ...

Sialons, as ceramic alloys of silicon nitride and aluminum oxide, were developed as an economically and fimctionally superior alternative to H PSN (see above). This alloying imposes increased high-temperature mechanical (flexural and tensile strengths, fracture toughness, hardness, wear resistance), thermal (thermal shock resistance) and chemical properties (corrosion and oxidation resistance) compared to unalloyed silicon nitride (see Table 11.13). 

Silicon nitride (Si3N4) based fibers are also of interest and several companies are on the verge of introducing a commercial product [20,21]. Dow s HPZ Si3N4 fibers have elastic moduli of 250-260 GPa and tensile strengths of = 2.5 GPa [20]. Tonen s Si3N4 fibers have elastic moduli of 300 GPa and tensile strengths of = 2.5 GPa [21]. By comparison, the elastic modulus of sintered, hot pressed silicon runs approximately 300-350 GPa [22]. 

C. W. Li, J. Wimmer and J. J. Nick, Tensile Strength of an In Situ Reinforced Silicon Nitride Exhibiting R Curve Behavior, ECD meeting, January 2003, submitted to Ceramics Transactions. 

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