Encapsulation of abrasive particles by plasma CVD

A new abrasive material for high-temperature cutting processes has been designed, which combines hardness and chemical stability, by encapsulating hard particles (SiC) with an inert metal oxide film (alumina). Using a circulating fluidised bed reactor system and the plasma chemical vapour deposition (CVD) technique, the coating is very uniform and it can be combined with a subsequent surface treatment for improved adhesion to the bonding matrix. A barrier layer thickness of 1 μm is sufficient to stabilize the particles in a Ni-alloy matrix at 1000 °C. Partial film removal by attrition during the film deposition process causes local dissolution at the edges.