The Study of the Electrospark Coating Effect on the Heat Removal Property of Hard Alloy

Abstract

The effect of a protective coating on the heat removal properties of a cutting plate made of VK8 tungsten-containing hard alloy has been studied. The article provides a sequence of measurements made by a thermal imager and a thermograph to install a mechanism for heat removal by a protective coating. The factors affecting the fault in temperature measurements in a static experiment by means of a thermal imager are described. The time to maximum temperature transferred from the heated counterbody to the hard alloy with and without coating has been obtained. The exposure time of the maximum temperature transmitted from the counterbody to the alloys under study has been fixed. It has been demonstrated that a multilayer electrospark coating based on Ni, Cu, Fe, Cr, W reduces the maximum temperature under the same test conditions by 42%, while the surface cooling rate at the point close to the cutting edge increases by 53%. The data obtained show the effect of the protective coating on the heat removal property of the hard alloy. The time of heat propagation over the entire surface of the test sample and the cooling time have been studied by means of a thermograph. There is a temperature difference of 103°С for the alloy without coating that has been calculated simultaneously between the points on the cutting edge and at a distance of 2 mm lower along the front surface, while for the alloy with a protective coating the difference was 79°С, it is less by 24%. The thermograms of alloys with and without coating are clearly shown at time to maximum temperature on the surface. The work of the coating to remove heat from the point of contact with the heated counterbody has been proven, and the heat removal property is explained by the composition of the coating obtained by electrospark alloying with electrodes based on Cu, Ni, Fe, W, and Cr