Technological principles for microtexturing the operating surfaces of ceramic cutting inserts by electrical discharge machining

Abstract

The article describes the technological principles of electrical discharge machining of the surface layer of SiAlON dielectric ceramics based on the artificial creation of conductive conditions of the ceramics’ surface layer, making it possible to form microtextures such as microgrooves and microwells/holes. It has been established that the processing stability between the electrode tool and the ceramic insert is increased by the deposition of electrically conductive coatings to ceramic inserts and supplying finely dispersed ZrO2 and TiO2 assisting powders into the interelectrode gap merged in a dielectric medium. The resistance tests carried out have shown that the use of compounds based on hard thermostable nitrides of refractory metals (AlCrTiNbSi)N and TiN-(AlCrTi)N as coatings with subsequent microtexturing provides a mutually reinforcing effect and makes it possible to increase the wear resistance of ceramic inserts up to 2.6 times when turning an Inconel 718 heat-resistant nickel alloy.