High Temperature Oxidation Behaviors of Ni-Cr Based Thermal Sprayed Coatings

Abstract

Ni-Cr coating and Ni-Cr/ZrO2 gradated coating were deposited on C45 carbon steel by high velocity arc spraying and micro-plasma spraying to solve the high temperature oxidation problem of medium carbon steel components. The oxidations of Ni-Cr coating, Ni-Cr/ZrO2 gradated coating and C45 carbon steel substrate were carried out for up to 108 hours in air atmosphere at 1100°C. The oxidation behaviors were investigated after detailed examinations by thermal gravimetric analysis (TGA), x-ray diffraction (XRD) and scanning electron microscopy (SEM). Ni-Cr coating and Ni-Cr/ZrO2 gradated coating show similar and low dynamics curve near to the logarithms function. Surface observations with SEM and XRD reveal that the oxidizing surface of the C45 carbon steel substrate is mainly a loose spherical structure consisted of mainly Fe2O3 and Fe3O4. The surface structures of Ni-Cr coating and Ni-Cr/ZrO2 gradated coating after 108 hours oxidization are rather denser than that of C45 carbon steel, which can effectively improve the properties of the oxidation resistance of C45 carbon steel substrate.