Sintered polycrystalline diamond material with extremely fine microstructures

Abstract

A sintered polycrystalline diamond material (PCD) of extremely fine grain size is manufactured by sintering a diamond powder with pre-blended catalyst metal under high pressure / high temperature (HP / HT) processing. The PCD material has an average sintered diamond grain structure of less than 1.0 μm.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This patent application claims priority to co-pending U.S. provisional patent application No. 60 / 717,227, filed Sep. 15, 2005 entitled “Sintered, Polycrystalline Diamond Compact with Extremely Fine Microstructures”, the disclosure of which is incorporated herein by reference in its entirety.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH [0002] Not applicable. NAMES OF PARTIES TO A JOINT RESEARCH AGREEMENT [0003] Not applicable. SEQUENCE LISTING [0004] Not applicable. BACKGROUND [0005] 1. Technical Field [0006] The disclosed embodiments generally relate to the field of sintered diamond cutting and forming tools and more particularly to such diamond tools having extremely fine microstructures imparting improved tool properties, machinability, and an ability to impart improved surface finish to workpiece materials. [0007] 2. Description of the Related Art [0008] Polycrystalline diamond (PCD) is used extensively in industrial applications...

AI Technical Summary

Benefits of technology

[0019] In an exemplary embodiment, a polycrystalline (PCD) body has diamond crystals that have an arithmetic mean, as-sintered diamond grain size less than 1 μm. In another embodiment, the PCD body comprises grain sizes greater than about 0.1 μm and less than about 1.0 μm. In still another embodiment the as-sintered grain size of a PCD body is substantially uniform. In a further embodiment, the PCD body is monolithic; there are no added bonding phases, such as carbides, nitrides, or borides, in the PCD body. An embodiment of a PCD body may have an oxygen content less than about 0.05 weight percent. In still another embodiment of a PCD body, the nitrogen content is less than about 0.01 weight-percent. A PCD body embodied herein may have diamond crystals wherein at least 63% of the crystals have a grain size that is less than 1.0 μm. Another embodiment is a PCD body which has a mean as-sintered grain size between about 0.1 μm and 1.0 μm, with a body thickness greater than about 0.5 mm.

Problems solved by technology

However, PCD as currently produced, does not provide extremely smooth cut, drawn or otherwise formed workpiece surfaces.

Single crystal diamond, while expensive, anisotropic, and limited in size, remains the preferred tool material for single point turning of optical materials or drawing of highly finished, fine wire.

Mechanical failure, from limited strength and impact resistance, of PCD tools is also common

Finer, uniform, as-sintered diamond grain sizes, for example, of about 0.1 μm to about 1.0 μm (referred to as “submicron”) have proven challenging to produce commercially using the PCD manufacturing process described above.

Submicron diamond particles are difficult to produce, and have proven difficult to handle during blending and mixing due to their high surface area's ability to attract and retain contaminants that affect the sintering process and product properties.

Submicron diamond particles have low packing densities that cause problems during loading of shielding enclosures and HP / HT processing.

The very fine pores between the submicron diamond grains in the initial diamond particle mass are difficult to uniformly penetrate with catalyst metal, leading to incomplete bonding and sintering between diamond particles.

It is almost always observed that the high surface area of submicron diamond powders causes the diamond solution-reprecipitation process to occur non-uniformly.

This leads to non-uniform detrimental diamond grain growth and other complications that make the production of larger parts unfeasible when final diamond grain sizes less than 1 micron are attempted.

These non-uniform materials were not hard enough to be useful as cutting tools.

The wear resistance, strength, and thermal stability of this product will be substantially inferior to true PCD.

Because no catalyst metal is present, the application does not describe a true PCD product; the product will have significant defects, and will be difficult to produce due to inherent problems of handling fine powders.

The prior art falls short of achieving a submicron particle size.

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