Coated Abrasives

a technology of coating and abrasives, applied in the field of coating abrasives, can solve the problems of diamond particles being susceptible to graphitisation of the surface of diamond particles, diamond particles being susceptible to oxidative and chemical attacks, and poor retention of particles in the bonding

Inactive Publication Date: 2008-02-14
EGAN DAVID PATRICK +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Common problems in applications are retention of particles in the bond matrix, and resistance against oxidative and chemical attack during the sintering process and the subsequent application.
A problem with the use of titanium carbide coatings where the bond matrix contains bronze or Cu is that these materials tend to react with the titanium carbide, such that it may be reacted away.
The diamond particles are then susceptible to graphitisation of the diamond particle surfaces, where the bond matrix consists of metals that are typically used as solvent / catalysts for diamond synthesis.
This process of graphitisation of the diamond surface not only weakens the particles but may also result in poorer retention of the particles in the bond.
At the sintering temperatures this oxygen is liable to attack the surface of the diamond particles, which weakens the particles.
Further, loss of diamond particles from the bond matrix by pull-out of the particles is a common reason for loss of performance, caused by poor adhesion of the particles to the bond matrix.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0034]Diamond grit from Element Six, 40 / 45 US mesh size, was coated in a CVD process to produce TiC coated diamond according to general methods commonly known in the art. The CVD TiC coated diamond was then used as the substrate for the second coating step.

[0035]1,000 carats of this TiC coated diamond, 40 / 45 US mesh size, was placed in a magnetron sputter coater with a rotating barrel and a large pure titanium metal plate as the target. The coating chamber was evacuated, argon was admitted and the power turned on to form plasma. Sputtering power was increased to 10 A (400V) on target while rotating the barrel to ensure an even coating on all the diamond particles at 20 sccm argon pressure. Methane gas was admitted to achieve an Optical Emission Measurement of 50%, and coating continued for 30 minutes. Subsequently, coating using methane gas was continued at an Optical Emissions Measurement of 60% for a further 30 minutes. Coating using methane gas was continued at an Optical Emissio...

example 2

[0038]CVD TiC coated diamond, produced in a first coating step as described in Example 1, was used as the substrate for the second coating step. 1,000 carats of this TiC coated diamond, 40 / 45 US mesh size, was placed in a magnetron sputter coater with a rotating barrel and a large pure titanium metal plate as the target. The coating chamber was evacuated, argon was admitted and the power turned on to form plasma. Sputtering power was increased to 10 A (400V) on target while rotating the barrel to ensure an even coating on all the diamond particles at 20 sccm argon pressure. Methane gas was admitted to achieve an Optical Emission Measurement of 50%. While continuing coating the Optical Emissions Measurement was increased gradually to 100% in 165 minutes. Coating without using methane was continued for 30 minutes. The total coating time was 195 minutes. The coated diamond was allowed to cool before removing from the chamber.

[0039]An analysis of this coated diamond was undertaken, cons...

example 3

[0041]CVD TiC coated diamond, produced in a first coating step as described in Example 1, was used as the substrate for the second coating step. 1,000 carats of this TiC coated diamond, 40 / 45 US mesh size, was placed in a magnetron sputter coater with a rotating barrel and a large pure titanium metal plate as the target. The coating chamber was evacuated, argon was admitted and the power turned on to form plasma. Sputtering power was increased to 10 A (400V) on target while oscillating the barrel to ensure an even coating on all the diamond particles at 20 sccm argon pressure. Coating with titanium metal continued at 2 kW (420V, 10 Amps) for 30 minutes. Methane gas was admitted to achieve an Optical Emission Measurement of 60%. This was continued for 30 minutes. Methane admission was stopped, and coating with titanium metal alone continued for 30 minutes. Methane gas was again admitted to achieve an Optical Emission Measurement of 60%. This was continued for 30 minutes. Lastly, meth...

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Abstract

A coated super-hard abrasive comprises a core of super-hard abrasive material, which is typically diamond or cBN based, an inner layer of a metal carbide, nitride, boride, boronitride or carbonitride chemically bonded to an outer surface of the super-hard abrasive material and one or more outer layers of a metal carbide, nitride, boride or carbonitride physically deposited on the inner layer. In the case of a single outer layer, the single outer layer has a composition gradient extending through its thickness, and in the case of more than one outer layer, the composition of each layer is different to provide a gradient of material through the various layers. In the case of several outer layers, each layer may also include a composition gradient.

Description

BACKGROUND OF THE INVENTION[0001]This invention relates to coated abrasives, a process for their production, and to coated abrasives for use in abrasive-containing tools.[0002]Abrasive particles such as diamond and cubic boron nitride are commonly used in cutting, grinding, drilling, sawing and polishing applications. In such applications, abrasive particles are mixed with metal powder mixes, then sintered at high temperatures to form bonded cutting elements. Typical bond matrices contain iron, cobalt, copper, nickel and / or alloys thereof.[0003]Common problems in applications are retention of particles in the bond matrix, and resistance against oxidative and chemical attack during the sintering process and the subsequent application.[0004]These problems are commonly addressed by coating the abrasive particles with metals or alloys which bond chemically to the particle, and alloy to the bond matrix. Typically, chemical vapour deposition (CVD) or physical vapour deposition (PVD sputte...

Claims

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Application Information

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IPC IPC(8): B24D11/00C04B41/52C09K3/14
CPCB24D11/001C09K3/1445C09K3/1436C04B41/52
InventorEGAN, DAVID PATRICKENGELS, JOHANNES ALEXANDERFISH, MICHAEL LESTER
OwnerEGAN DAVID PATRICK