INFLUENCE NICKEL CLADDING PARAMETERS ON THE PROPERTIES OF TUNGSTEN CARBIDE POWDERS

Abstract

The process of cladding of particles of hard alloys based on tungsten carbide with a coating based on nickel by the method of chemical deposition from salt solutions has been investigated. The effect of the chemical composition of the solution, namely acidic based on nickel sulfate salt and alkaline based on nickel chloride, has been studied. It is shown that the coating that is formed does not consist of pure nickel, but is a complex system, where, along with nickel, phosphorus is present in an amount from 2 to 10 wt%. depending on the conditions of receipt. It was found that in both cases the deposition rate of nickel was 8-10 μm / h, while the use of an alkaline solution makes it possible to obtain a coating with a high nickel content and a low phosphorus content. It was found that cladding of particles leads to a change in their physical properties: shape and size. The shape of the clad particles becomes more close to spherical with different thickness of the coating on the particles, which is due to the different surface area and shape of the initial particles. The deposition of a nickel-phosphorus coating on the particles of tungsten carbide powder leads to a change in its size in terms of particle size distribution. The effect of cladding on the technological properties of tungsten carbide powders was investigated, it was found that cladding leads to an increase in fluidity and, accordingly, to an increase in the bulk density of the powder, due to a decrease in the specific surface area of particles and smoothing of their surface relief, which in turn leads to a decrease in the roughness of the particle surface. The research results can be useful in the creation of carbide products for various functional purposes, and, first of all, armor-piercing cores of small arms bullets. The cladding of tungsten carbide hard-alloy particles with a nickel-based coating from an alkaline solution makes it possible to obtain composite powders with high physical and technological characteristics.