ISOTHERMAL OXIDATION BEHAVIOR AND THERMAL SHOCK RESISTANCE OF THREE-KIND Cr COATINGS ON PCrNi3MoVA STEEL

Abstract

Isothermal oxidation behavior at 900 °C for 5 h and thermal shock resistance at 900 °C of three-kind Cr coatings prepared by electroplating, magnetron sputtering and multi arc ion plating technologies on PCrNi3MoVA steel were investigated. Micromorphologies of three-kind Cr coatings before and after tests were observed by the scanning electron microscopy and crystallization phase identification was studied by the X-ray diffraction. Oxidation of three-kind Cr coatings showed characteristic morphologies of electroplating Cr coating with microcrack, magnetron sputtering Cr coating with columnar crystal and multi arc ion plating Cr coating with microdroplet during coating preparation were main reasons for different properties. Correspondingly, the failure mechanisms of delamination, through spalling caused by through cracks and through spalling caused by surface spalling of droplet were obtained by thermal shock test. The results indicate that multi arc ion plating, for its property of high temperature resistance, could be a more effective approach to prolong gun barrel life.