Fabrication and mechanical properties of Al{sub}2O{sub}3/5volNi composite by a powder coating technique

摘要

Ni-coated Al{sub}2O{sub}3 powders were prepared by heterogeneous precipitation method. XRD patterns showed that the amorphous coating layer was crystallized to NiO at 550°C for 2 h in air, and then NiO was completely reduced to Ni at 700°C for 4 h in hydrogen atmosphere. TEM micro graph showed that Ni particles with the size of about 2Onm in the coating layers were spherical and weakly agglomerated. The bending strength and fracture toughness of the Al{sub}2O{sub}3/5vol%Ni composite prepared at 1450°C and 2OMPa were 510 ± 10 MPa and 4.2± 0.1 Mpa·m{sup}(1/2), respectively, which were much higher than those of monolithic Al{sub}2O{sub}3. Microstructure observations found that most of Ni particles were located at the Al{sub}2O{sub}3 boundary, and a few within the Al{sub}2O{sub}3 grains.