Preparation and Reparation and Mechanical properties of Nanocobalt Coated AL_2O_3-TIC Composites

摘要

AI_2O_3-TiC composites were fabricated by hot-pressing Cobalt coated powders at low temperature through liquid phase sintering. Cobalt coating layers effectively hinder the growth of grain and harmful reaction between Al_2O_3 and TiC particles, which would improve the mechanical properties of Al_2O_3-TiC composites. The hardness decreases with the increase of Co content and the bending strength was enhanced to 782MPa owing to the grain refinement effect of Co phase. The fracture toughness, about 9.23 MPa.m~(1/2), was measured for the composites containing 3wt% Co sintered at 1550℃. SEM images of fracture surface show that the toughening effect should be attributed to the conversion of fracture mode caused by the Co phase.