Abstract
The Mo-Ni-B cermets were sintered in cans at various temperature by the hot isostatic pressing (HIP), to obtain the thick layers of the cermet securely bonded with steel. The bonding strength between cermet and steel HIPed at 1393-1523K was enough, but the mechanical properties of HIPed cermet were inferior to those of the vacuumsintered cermet. Especially, the fracture toughness (K1C value) was 65% of the latter.
The gas evaporation from the cermet was investigated during the sintering in Ar, and evaporation of CO and boride gas at 1300K-was clarified. In HIP process, this evaporation could not occur sufficiently. The remained carbon reacted with Ta, W or Mo, and the brittle complex carbides were formed certainly. It is thought that the poorness in mechanical properties of HIPed cermet is due to the excess of carbon, oxygen and so on.
