Research on performance and improvement of electroplated diamond tools I

In response to the above problems, people have adopted various measures to solve the bonding force between diamond and coating metal. This article comprehensively introduces the methods for improving the performance of electroplated diamond tools that have been developed at home and abroad in recent years, and summarizes and categorizes them, hoping to give people a detailed and clear understanding.

Because diamond has a series of excellent physical and chemical properties such as high hardness, high strength, high wear resistance and small linear expansion coefficient, it is used to make diamond tools for processing hard and brittle materials that are difficult to machine. The preparation of diamond tools by electroplating is to consolidate loose diamond particles in the electroplating layer through metal electrodeposition, so that the diamond particles have cutting ability. Diamond tools prepared by electroplating have a low manufacturing temperature, which avoids heat loss to the diamond, and the production process is simple, with low equipment investment, short manufacturing cycle, easy molding, and can be repaired. Therefore, electroplated diamond products include various grinding wheels, grinding heads, assorted files, cutting knives, dressing rollers, geological drills, hole reamers, internal and external circular cutting blades, reamers, wire saws and other special tools, which are widely used in industrial fields such as machinery, electronics, construction, drilling, and optical glass processing [1-3].

At present, when electroplating is used to prepare diamond tools at home and abroad, the main problem is that the bonding force between the coating matrix metal and the diamond particles is low. When the diamond particles are subjected to force during use, they are easy to loosen and fall off, resulting in a short service life. The main reason for these phenomena is that the manufacturing temperature is low when diamond tools are prepared by electroplating, which makes the surface of diamond particles difficult to be wetted by ordinary metals. Not only is there no strong chemical bonding, but gaps often occur. In addition, due to the influence of the electroplating process, the available types of diamond tool coating metals are limited (limited to a small amount of metals such as nickel and chromium and their alloys), which is not as extensive as the metal types used in hot press tools.

1. Improve the matrix material

In electroplated diamond tools, the coating supports and binds the diamond and is called the matrix or matrix metal. It determines whether the diamond particles can fully exert their cutting effect. It is generally required to meet performance requirements such as high hardness, high wear resistance and high toughness. Therefore, people first consider improving diamond tools by improving the performance of the matrix material.

1.1 Alloying of matrix metal

Although a single coating (such as nickel) has high strength, especially toughness, its hardness is generally low, so people often use alloy coatings.

1.1.1Ni-Co binary alloy coating [1-5]

Cobalt can not only improve the strength of nickel metal (the matrix compressive strength of nickel-cobalt alloy is 1600MPa), but also improve the heat resistance of the matrix metal. The NiCo binary alloy matrix metal strength limit at 800°C is 500MPa, and it can also improve the toughness of the matrix metal.