Abrasive tool and process of manufacture

Claim 2

An abrasive tool, adaptable for dressing cutoff, grinding and other abrasive wheels, which comprises a tough metal matrix formed of pressed metal particles, the metal being selected from the group consisting of cobalt, iron, nickel and copper and alloys and mixtures thereof, in which matrix are embedded a plurality of substantially uniformly dispersed diamonds, each encircled by fine particles of hard, abradable material, the hard carbide material being selected from the group consisting of carbides of metals such as tungsten, tantalum, titanium, chromium and mixtures, the particles of said hard carbide constituting an abradable barrier at the diamond surface in the matrix, the interstices between the hard particles and the metal particles of the matrix being partly filled with small amounts of particles of the matrix metal due to pressing at high temperature for a short time, the bond between the diamond and the encircling material being readily abradable due to said hard material.

Claim 3

An abrasive tool in accordance with claim 1 wherein the hard material is tungsten carbide and the interstices are filled with particles of cobalt from the matrix metal.

Claim 4

An abrasive tool in accordance with claim 1 wherein the hard material is tungsten carbide and the matrix is formed of particles of an iron alloy.

Claim 5

An abrasive tool in accordance with claim 1 wherein the cross-sectional area ratio of hard material to diamond on the face of the tool is between about 3:1 and 10:1.

Claim 6

A process of making an abrasive tool which is adaptable for dressing cutoff, grinding and other abrasive wheels, and which is composed of a metal matrix formed of pressed metal particles, the matrix having embedded therein a plurality of substantially uniformly dispersed diamonds each encircled by fine particles of hard abradable material, the interstices between the hard particles and the metal particles of the matrix being partly filled with small amounts of metal, said process comprising coating a mass of water-wet diamonds with fine particles of a hard carbide material to form individual balls, the particles of said hard carbide constituting an abradable barrier at the diamond surface in the matrix, dispersing a powdered metal around and in complete contact with the balls to form a uniform mixture of coated balls and metal powder, applying heat and pressure to the mixture in amounts sufficient to raise the temperature to at least the sintering temperature of the metal, and then maintaining the heat and pressure for a period sufficient to permit small amounts of the metal to fill the interstices between the matrix and the hard abradable particles surrounding each diamond to thereby form a shaped abrading tool.

Claim 7

A process of making an abrasive tool which is adaptable for dressing cutoff, grinding and other abrasive wheels, and which is composed of a metal matrix formed of pressed metal particles, the matrix having embedded therein a plurality of substantially uniformly dispersed diamonds each encircled by fine particles of hard abradable material, the interstices between the hard particles and the metal particles of the matrix being partly filled with small amounts of metal, said process comprising coating a mass of water-wet diamonds with fine particles of a hard carbide material to form individual balls, the particles of said hard carbide constituting an abradable barrier at the diamond surface in the matrix, dispersing a powdered metal around and in complete contact with the balls to form a uniform mixture of coated balls and metal powder, applying heat and pressure to the mixture in amounts sufficient to raise the temperature to at least the sintering temperature of the metal, and then maintaining the heat and pressure for a period sufficient to permit small amounts of the metal to fill the interstices between the matrix and the hard abradable particles surrounding each diamond to thereby form a shaped abrading tool.

Claim 8

A process in accordance with claim 5 wherein the hard abradable material is selected from the group consisting of tungsten carbide, tantalum carbide, titanium carbide, chromium carbide and mixtures thereof.

Claim 9

A process in accordance with claim 6 wherein the metal of the matrix is selected from the group consisting of cobalt, iron, nickel and copper and alloys and mixtures thereof.

Claim 10

A process in accordance with claim 5 wherein the mixture is heated to at least about 2400* F. and the pressure is maintained at least at about 500 pounds p.s.i. for at least about 2 minutes.

Claim 11

A process in accordance with claim 5 wherein the ratio of cross-sectional area of hard material to diamond on the face of the tool formed is between about 3:1 and 10:1.

Claim 12

A process in accordance with claim 5 wherein the mixture is first cold-pressed to the approximate shape of the tool before applying heat and pressure.

Claim 13

A process in accordance with claim 5 wherein the tool formed thereby is composed, by volume, of about 11.2 percent diamond, about 50.7 percent hard material, and about 38.1 percent metal.

Claim 14

A process in accordance with claim 5 wherein the tool formed thereby is composed, by volume, of about 5.6 percent diamond, about 53.9 percent hard material, and about 40.5 percent metal.