Polycrystalline grits and associated methods

Abstract

Polycrystalline grits and methods of making grits which allow for a high degree of shape and size distribution control, as well as improved abrasive performance are described and disclosed. In one aspect, an abrasive slurry can be formed into a plurality of abrasive precursors arranged on a substrate using screen-printing or other techniques. The abrasive slurry can include a binder and a plurality of abrasive particles. The abrasive precursors on the substrate can then be covered with a pressure medium and then subjected to pressure and temperature conditions sufficient to cause sintering of the abrasive particles to form polycrystalline grits. The polycrystalline grits produced by such methods can have a substantially uniform shape and size distribution.

Description

RELATED APPLICATIONS [0001] This application is a divisional application of U.S. patent application No. 10 / 925,894, filed Aug. 24, 2004, which is incorporated herein by reference.FIELD OF THE INVENTION [0002] The present invention relates to methods for use in connection with producing abrasive particles. More particularly, the present invention relates to polycrystalline grits and accompanying methods for making such grits. Accordingly, the present invention involves the fields of chemistry, metallurgy, materials science, and high pressure technology. BACKGROUND OF THE INVENTION [0003] Abrasive particles have long been used in numerous applications, including cutting, drilling, sawing, grinding, lapping and polishing of materials. A wide variety of abrasive particles can be used, depending on the specific application and workpiece. Typically, extraordinarily hard abrasive particles such as diamond and cubic boron nitride (cBN) are referred to as superabrasive particles. [0004] Abra...

AI Technical Summary

Benefits of technology

[0010] Accordingly, the present invention provides a method for forming polycrystalline grits which allows for a high degree of shape and size distribution control, as well as improved abrasive performance. In one aspect of the present invention, a method of forming polycrystalline grits can include forming an abrasive slurry into a plurality of abrasive precursors arranged on a substrate. The abrasive slurry can include a binder and a plurality of abrasive particles. Once on the substrate, the binder can be optionally removed in a dewaxing step. Further, the abrasive precursors can be at least partially covered with a pressure medium to form a precursor assembly. The precursor assembly can then be subjected to pressure and temperature conditions sufficient to cause sintering of the abrasive particles to form polycrystalline grits.

[0015] In another aspect of the present invention, a plurality of precursor assemblies can be assembled to form a multi-layered precursor assembly. This configuration can allow for maximizing usage of limited reaction volumes in high pressure devices and increased production volumes.

[0016] In yet another aspect of the present invention, polycrystalline grits can be formed which include sintered abrasive particles. These polycrystalline grits can have substantially unaltered surfaces. A wide variety of shapes and sizes of polycrystalline grits can be readily manufactured. Additionally, the polycrystalline grits produced by the methods of the present invention can have a substantially uniform shape and size distribution. In many cases, the uniformity can be characterized by a size distribution of less than about 50 μm, and in some cases less than about 5 μm. Further, polycrystalline grits can be formed which allow for microfracture during abrasive applications such that their useful is extended and cutting speed can be maintained over extended periods of time.

Problems solved by technology

Cubic presses are typically cheaper and easier to operate, but also have limited reaction volumes.

Similarly, belt apparatuses can provide larger reaction volumes, but tend to be more expensive and difficult to operate successfully.

Costs of production per unit weight for superabrasive compacts tend to increase with increasing particle size, primarily due to the time required to grow large crystals.

Conversely, the cost of production for abrasive compacts tends to decrease with increasing size.

While such processes do produce useful grits, they tend to have highly irregular shapes and broad particle size distributions.

However, this method tends to be expensive and time consuming, despite improved regular shapes and consistent size distributions.

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