対称的に組成傾斜したアルミナ系高次機能セラミックスの製造と性質

Abstract

Hyperfunctional Al2O3 ceramics with symmetrically graded structures of the A12O3/TiC/ Ni/TiC/Al2O3 and Al2O3/Cr3C2/Ni/Cr3C2/Al2O3 were fabricated by SHS/HIP. The SHS/HIP is both a new sintering process of such heterogeneous materials with different sintering tempreratures and a recycling process using a chemical oven of Si waste in zinc smelting. Strong residual compressive stress of 200-800 MPa were produced in the outer Al2O3 layers mainly due to the thermal expansion mismatch between the outer Al2O3 and inner cermet layers. The compressive stress acted to enhance intrinsic toughness and hardness of Al2O3. Moreover, the local stress change produced by the surface damage reached to the opposite side through disturbance of the internal stress balance of compression/tension/ compression designed in these materials. This effect is potentially available to give a damage detectable function.