Characterisation and Corrosion-Erosion Behaviour of Carbide based Thermal Spray Coatings

Abstract

Thermal spraying has emerged as a suitable and effective surface engineering technology and is widely used to apply wear, erosion and corrosion protective coatings for various kinds of industrial applications. Cr 3 C 2 -based coatings have been applied to a wide range of industrial components. Cr 3 C 2 -NiCr coatings offer greater corrosion and oxidation resistance, also having a high melting point and maintaining high hardness, strength and wear resistance up to a maximum operating temperature of 900 C. The corrosion resistance is provided by NiCr matrix while the wear resistance is mainly due to the carbide ceramic phase. This paper reviews the performance, developments and applications of Cr 3 C 2 -NiCr thermal spray coatings for corrosion/erosion-corrosion under different types of environments and outlines the characterization of Cr 3 C 2 -NiCr coatings with respect to their microstructure and mechanical properties, together with some brief characterisation work by the author for HVOF sprayed 75Cr 3 C 2 -25NiCr coating on T91 boiler steel.