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Home  >  Journal list  >  Journal of the Society of Materials Science, Japan  >  Vol.60  No.11 (2011)  >  pp.1037-1042

Journal of the Society of Materials Science, Japan
<<Previous article Vol.60  No.11 (2011)   pp.1037 - 1042 Next article>>

Effect of Sintering Additive on the Strength and Fractography of Hot-Pressed Silicon Nitride Ceramics

Kaname MORI1), Akira UCHIYAMA2), Yoshiki SHOUJI3) and Hideaki OKUMURA1)
1) Eng., Teikyo Univ.
2) Teikyo Univ.
3) Kanto Auto Works, Ltd.


Several silicon nitride ceramics with different compositions and amounts of sintering additive were fabricated by hot-press method. The effect of sintering additive on the sinterability, flexural strength and fractography was examined. The flexural strength of silicon nitrides sintered with alumina as an additive were not high at approximately 400MPa, although the sinterability was good in that bulk densities of 3.05-3.18 × 103kg m-3 were obtained. The sinterability of silicon nitrides sintered with yttria as an additive resulted in low bulk densities of approximately 2.7 × 103kg m-3, with flexural strength ranging from 370 to 650MPa. The sinterability of silicon nitrides that were sintered with both yttria and alumina additives resulted in relatively high bulk densities of approximately 3.21 × 103kg m-3 and extremely high flexural strength in the range of 900 to 1140MPa. The fractography of fracture origin was dependent on the type of sintering additive used; an inclusion size of approximately 30μm for the alumina additive, pores for the yttria additive and small secondary sintering defects for both yttria and alumina as additives were observed at the respective fracture origins.


Keyword:
Ceramics, Silicon nitride, Sintering additive, Strength, Fractography, Fracture origin, Sinterability

Received: January 12, 2011
Published online: November 21, 2011
Copyright (c) 2011 by The Society of Materials Science, Japan

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