Fabrication and mechanical Properties of Al_2O_3/5Vol/100 Ni Composite by a Powder Coating Technique

摘要

Ni-coated Al_2O_3 powders were prepare by heterogeneous precipitation method. XRD patterns showed that the amorphous coating layer was crystallized to NiO at 550 deg. C for 2 h in air, and then NiO was completely reduced to Ni at 700 deg. C for 4 h in hydrogen atmosphere. TEM micrograph showed that Ni particles with the size of about 20nm in the coating layers were spherical and weakly agglomerated. The bending strength and fracture toughness of the Al_2O_3/5vol/100 Ni composite prepared at 1450 deg. C and 20Mpa were 510 ± 10 Mpa and 4.2 ± 0.1 Mpa.m~1/2, respectively, which were much higher than those of monolithic Al_2O_3.