Coated super hard particles and composite materials made from coated superhard particles

摘要

A method for coating superhard particles comprises mixing superhard particles with MoO3 particles, the ratio of the superhard particles to the MoO3 particles being between 1:1 and 1:10 by weight, heating the mixture in a vacuum or protective atmosphere at a first temperature of no more than 795°C and heating the mixture at a second temperature of at least 830°C in an inert gas at a pressure of between 0.1 and 10 MPa. During the increase from the first to the second temperature, at least one annealing process in a vacuum or protective atmosphere is preferably performed. After heating the mixture at the second temperature, a heat treatment in an atmosphere selected from a vacuum, hydrogen, nitrogen CO or CO2 may be performed. Also disclosed are coated particles having a superhard material core and a coating of molybdenum carbide. A composite material comprises the coated particles and a metallic binder comprising copper, silver or gold or alloys or mixtures thereof. A method of fabricating said composite material comprises forming a green body from a mixture of metallic binder material and the coated particles and electrical resistance sintering the mixture by applying current and pressure.