Techniques and materials for the accelerated removal of catalyst material from diamond bodies

Abstract

A method for making a thermally stable cutting element may include forming an acid mixture containing two different acid species by combining an acid solution and at least one acid-forming compound, wherein the at least one acid-forming compound is provided in solid form, and wherein the at least one acid-forming compound produces an acid that is different than the acid solution; treating at least a portion of a sintered diamond body by placing the sintered diamond body in the acid mixture, wherein the sintered diamond body comprises: a matrix phase of bonded-together diamond grains; a plurality of interstitial regions dispersed within the matrix phase; and a metal material disposed within a plurality of the interstitial regions; wherein the treating removes the metal material from at least a portion of the plurality of interstitial regions; and removing the sintered diamond body from the acid mixture after a predetermined length of time, wherein at least a portion of the diamond body removed from the acid mixture is substantially free of the metal material and is a thermally stable diamond body.

Description

CROSS-REFERENCE OF RELATED APPLICATIONS[0001]This application is a continuation of U.S. patent application Ser. No. 12 / 581,639 filed on Oct. 19, 2009, which pursuant to 35 U.S.C. §119, claims the benefit of U.S. Patent Application No. 61 / 106,912, filed on Oct. 20, 2008, which is herein incorporated by reference in its entirety.BACKGROUND OF THE INVENTION[0002]1. Field of Invention[0003]Embodiments disclosed herein relate generally to polycrystalline diamond constructions and cutting structures comprising the same and, more particularly, to methods and materials used for improving the thermal stability of polycrystalline diamond constructions and the polycrystalline diamond constructions resulting therefrom.[0004]2. Background Art[0005]Polycrystalline diamond compact (“PDC”) cutters have been used in industrial applications including subterranean drilling and metal machining for many years. In a typical application, a compact of polycrystalline diamond (PCD) (or other superhard mater...

AI Technical Summary

Benefits of technology

The patent text describes methods for making thermally stable cutting elements and diamond constructions. These methods involve treating a sintered diamond body by placing it in an acid mixture and removing the metal material from the interstitial regions, resulting in a thermally stable diamond body. The treated diamond body can then be used to make a thermally stable cutting element or a polycrystalline diamond construction. The technical effects of this patent include improved thermal stability and the ability to make high-quality cutting elements and diamond constructions.

Problems solved by technology

This heat causes thermal damage to the PCD in the form of cracks (due to differences in thermal expansion coefficients), which lead to spalling of the PCD body or layer, and / or delamination between the PCD body and substrate, and / or back conversion of the diamond to graphite in the PCD body causing rapid abrasive wear.

Conventional PCD is stable at temperatures of up to about 700 to 750° C., after which observed increases in temperature may result in permanent damage to and structural failure of PCD.

This deterioration in PCD is due to the significant difference in the coefficient of thermal expansion of the binder or catalyst material, e.g., as compared to diamond.

Upon heating of PCD during use, the catalyst material and the diamond lattice expands at different rates, which may cause cracks to form in the diamond lattice structure and result in deterioration of the PCD.

Damage is also due to the catalyzed formation of graphite at diamond-diamond necks at high temperatures, leading to loss of microstructural integrity and strength loss.

While conventional leaching processes with nitric / hydrofluoric acid mixtures are somewhat successful in removing the catalyst or binder material from the PCD, they tend to be time consuming, e.g., using mixtures of acids may easily take many weeks in order to leach out the catalyst or binder material.

Further, the use and handling of acid solutions such as hydrofluoric acid presents potential safety, health, and environmental dangers.

Still further, the use of such conventional leaching techniques presents certain limitations in the degree of catalyst and binder material, as well as other unwanted non-diamond materials, that may be removed from the PCD.

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