Galvanic bonding is a method of sputtering in which diamond particles are attached to the coated base and a layer of metal bonding is deposited from the electrolyte, covering and fixing the diamond grains. The method allows to obtain diamond-containing coatings on complex shaped surfaces and to create thin (up to 0.4 mm) diamond-containing elements and coatings.
The methods of attaching diamonds to a metal base are varied. In one embodiment, coarse grain diamond grains are first attached to the surface of the tool body, then a layer of fine grain diamond grains is applied, and the diamonds are finally infilled with electrodeposited metal. In addition, there is a technology of fixing diamond grains of different grain sizes on the tool body. In this case, the tops of the finer grains are located below the level of the tops of the larger grains. According to another technology, diamond grains of two grit sizes are deposited on the body of the insert at the same time. The efficiency of all these variants of diamond fixing, from the point of view of knife sharpening bars application, is practically the same.
The galvanic bond is in any case characterized by the fact that it holds the diamond grains only due to mechanical forces of adhesion, so the grains must be overgrown by the bond to a height of at least 65-70% of the grain size. The metal that securely holds the abrasive grain on the steel body is nickel. It provides the tool with high strength, durability and performance.
Electroplated diamond inserts provide intense metal removal and can be used for knife cutting edges that have significant damage (chips, gouges, etc). They work noticeably more aggressively than organic and metal-bonded bars with similar grain size. This is achieved due to protruding diamond grains, while in metal and organic bonds diamond grains are embedded in the binder and mixed with it. The grain size concentration in the layer is 100%.
At the same time, it should be noted that such stones will be inferior to stones on other binders in terms of the duration of work due to the thin layer of sputtering, which is actively erased in the process of sharpening. It is also important to take into account that when working with such diamonds on soft steels, hardness up to 58 HRC, this type of bars is produced faster than when working on steels with high hardness. Galvanic-bonded inserts do not require preparation for work (leveling, “cheering up”, etc.). In general, they are efficient and inexpensive solutions for fast sharpening.