Coating on pdc/tsp cutter for accelerated leaching

Abstract

A cutting element that includes a polycrystalline diamond layer having a cutting face and a diamond layer side surface, a substrate attached to the polycrystalline diamond layer, the substrate having a bottom surface and a substrate side surface, an interface between the diamond layer and the substrate, and a mask covering at least the bottom surface and the substrate side surface of the cutting element is disclosed.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims the benefit of U.S. Provisional Application 61 / 468,849 filed on Mar. 29, 2011, which is herein incorporated by reference in its entirety.BACKGROUND[0002]1. Technical Field[0003]Embodiments disclosed herein relate generally to polycrystalline diamond composites and cutting structures. More particularly, embodiments disclosed herein relate to methods of leaching polycrystalline diamond cutting elements.[0004]2. Background Art[0005]Polycrystalline diamond compact (“PDC”) cutters have been used in industrial applications including rock drilling and metal machining for many years. In a typical application, a compact of polycrystalline diamond (PCD) (or other superhard material) is bonded to a substrate material, which is typically a sintered metal-carbide to form a cutting structure. PCD comprises a polycrystalline mass of diamonds (typically synthetic) that are bonded together to form an integral, tough, high-strength ...

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Benefits of technology

[0016]Other aspects and advantages of the invention will be apparent from the following description and the appended claims.

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 polycrystalline diamond layer, delamination between the polycrystalline diamond and substrate, and back conversion of the diamond to graphite causing rapid abrasive wear.

As mentioned, conventional polycrystalline diamond is stable at temperatures of up to 700° C., after which observed increases in temperature may result in permanent damage to and structural failure of polycrystalline diamond.

Upon heating of polycrystalline diamond, the cobalt and the diamond lattice will expand at different rates, which may cause cracks to form in the diamond lattice structure and result in deterioration of the polycrystalline diamond.

However, thermal fatigue does not only occur at temperatures above 700° C. Rather, the differential expansion (between cobalt and diamond) even occurs at temperatures as low as 300-400° C., still causing thermal fatigue in the diamond body.

Further, damage to polycrystalline diamond can also result from the loss of some diamond-to-diamond bonds (from the initiation of a graphitization process) leading to loss of microstructural integrity and strength loss.

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