β-アルミナ焼結体の破壊じん性(<小特集>セラミック材料小特集)

概要

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The fracture toughness (K_<Ic>) of two kinds of polycrystalline β-alumina (hot-pressed (HP) and normally sintered (NS) ) were measured by the controlled surface flaw method as a function of temperature up to 1 400℃. The obtained K_<Ic> values for HP and NS decreased from 2.0 MN/m^<3/2> and 2.4 MN/m^<3/2> at room temperature, to 1.9 MN/m^<3/2> and 2.3 MN/m^<3/2> at 900℃, respectively. The brittle fracture in this temperature range initiated intragranularly from the initial intragranular flaw of Vicker's indentation. On the other hand, K_<Ic> of both HP and NS apparently increased with increasing temperature above 900℃. The reason of this rapid increase in K_<Ic>. may be attributed to the plastic behavior or thermal blunting effect at the crack tip, because the fracture initiated from the slow crack growth region. These results were discussed on the bases of the temperature dependence of their elastic moduli (E) and fracture energy (γ) , and also compared with K_<Ic> of single crystal β-alumina measured by the micro-indentation method at room temperature.
社団法人日本材料学会の論文
1982-10-15