Adhesion strength of Cu coating on substrate at different temperatures

Abstract

Flattening of an individual particle on the substrate is a unit cell for the coating formation in plasma spraying. In this study, individual Cu splats and coatings were collected on the AISI304 substrates at different temperatures by plasma spraying. Microstructures of the splats and coatings were observed by scanning electron microscope, and the adhesion strength of each coating was measured by tensile test. The coating hardness was also evaluated. The splats collected on the unheated substrate performed as splash shape, while most of the splats collected on the substrate at high temperatures exhibited as regular disc type. In particular, less nanopores could be found at the bottom surface of the disc shaped splats. The coating adhesion strength increased dramatically from 22 to 63 MPa with the increase in substrate temperature; the coating hardness also increased with the increase in substrate temperature. Accordingly, the coating performance has a close relation with the splats flattening behaviour on the substrates surface.