Toshio Kawanami

Mechanical Properties at High Temperature of High Purity Mullite Ceramics

Publisher Summary This chapter investigates the mechanical properties at high temperature, which were the flexural strength and creep resistance of high-purity mullite ceramics. Mullite is not a stoichiometric composition, as discussed in the phase equilibrium diagrams for Al2O3-SiO2 system. Therefore, the mechanical properties at high temperatures should change as a function of Al2O3/SiO2 ratio. Ohnishi revealed that mullite ceramics with 74-76wt% Al2O3 exhibited smaller degradation of strength and high creep-resistance, and reported impurity dependence of mechanical properties for near stoichiometric composition was investigated. The influence of the relationship between Al2O3/SiO2 ratio and impurity on the mechanical properties have been investigated. This chapter investigates the purpose of the influence of impurity of mullite ceramics prepared using the sol-gel method on the mechanical properties at high temperature.

Hiping Effects for ZrO2 Strengthened A12O3 based Nanocomposites

ZrO2 strengthened A12O3/SiC nanocomposites, A12O3/5vol%SiC/20 vol% ZrO2, were successfully fabricated by the pressureless sintering method. However, the pores and defects remained during pressureless sintering were found to decrease the fracture strength and toughness of A12O3/SiC/ZrO2 nanocomposites. To eliminate these pores and defects, the A12O3/SiC/ZrO2 composite was hot-isostatically pressed after pressureless sintering. The mechanical properties of A12O3/SiC/ZrO2 nanocomposites were significantly improved by the post HIPing. Especially, the fracture strength increased approximately twice by the HIP treatment.