Conical Tip Wear in Transition Deformation – Wear Map Construction under Cyclic Impact of Hardness Ceramic Materials

Abstract

Penetrator tip wear was investigated on an apparatus testing the impact on hard ceramic materials. The experimental tests were done on a vertical impact computerized test bench of original conception. Tapered diamond and carbide-metal pins were used as penetrators. It was noticed that in some situations the tip of the penetrator remained stuck in its target, acting as a Morse cone, due to the friction force between the penetrator and its target being higher than the reaction force of the collision between the two objects. This has led us to choose an angle of 1060 at the tip of the penetrator cone. For most tests we used a maximum strength of 40 N and a sintered carbide impact pin with a 1150 HV 30/15 hardness. For the study of the penetrator tip wear we have used a granite tile that owing to its high hardnes has enabled a noticeable wear of the tip. We have established a method and an algorithm for calculating the tip wear, based on images captured under a microscope after testing. A general finding is that in all tests, besides the cyclical impact deformation and the wear of coating that were tested, the wear of the tip of the pin which applies the impacts is also noticeable regardless of its shape (spherical, conical, etc), so much so that for a large number of cyclical impacts the pin tip wear must be taken into account. Variation curves are presented in the volume of wear material and of the maximum pressure p0 at the tip of the impactor, depending on the number of impacts. From the variation curve of the wear volume of material according to the number of impacts we’ve established an analytical relationship for the wear of the tip. A logarithmic formula allows for a relative assessment of the extent to which the tip is worn, as a function of the total number of incurred impacts.