| 摘要 |
1447794 Abrasive articles GENERAL ELECTRIC CO 25 Oct 1973 [1 Nov 1972] 49854/73 Heading C4V A composite abrasive body is obtained by (a) placing in a particulate metal container in contiguous layers a mass of cubic boron nitride crystals, metal to provide an alloy having a critical temperature of less than 1500‹ C. for wetting capillaries in the mass of cubic boron nitride and a body of material having an elastic modulus of at least 60,000,000 p.s.i., (b) disposing the metal container and its contents in a pressure-transmitting medium, (c) applying substantially isostatic abrasive to the metal container and the contents via the pressure-transmitting medium, the pressure being greater than 20,000 p.s.i. and less than the cubic boron nitride-stable pressure at the operating temperatures, the application of pressure being sufficiently long to substantially stabilize the dimensions of the metal container and the contents at least in planes through the metal container parallel to the interface between the metal and the cubic boron nitride layers, (d) simultaneously applying pressure to and heating the container and contents for a time sufficient to permit infusion of the alloy into the mass of cubic boron nitride crystals, the pressure being at least 500 p.s.i. and less than the cubic boron nitride-stable pressure at the operating temperatures and the heating being sufficient to exceed the critical wetting temperature of the alloy, (e) maintaining substantially at a static pressure the container and contents during cooling, and (f) recovering the resulting composite abrasive body in which a layer of metalbonded cubic boron nitride crystals is directly bonded to the body of material of high elastic modulus. The material having the elastic modulus of at least 60,000,000 p.s.i. may be sintered silicon carbide. The pressure-transmitting medium may be particulate and may consist of particles of hexagonal boron nitride. Suitable bonding metal alloys are NiAl (80- 90% by weight Ni), CoAl (less than 20% by weight Co), FeAl (less than 15% by weight Fe) and NiCr (less than 25% by weight Cr). |
