Characterization of vacuum plasma spray VPS - W coating deposited on stainless steel substrates

Abstract

In this paper, studied was the melting of W powder particles in plasma, their behavior at oxidation as well as the mechanism of hardening on the surface of the substrate. Tungsten coating layers were deposited with vacuum plasma spray technology (VPS) on the test specimens of steel Č.4171 (X15Cr13 EN10027). VPS technology has advantages over the APS technology due to decreased oxidation of melted powder particles, by producing a coating with a controlled proportion of micro pores and greater uniformity of the deposited layers. Evaluation of mechanical characteristics of the layers was done by examining the microhardness using the HV0.3 method and tensile bond strength by tensile testing. The microstructures of the deposited layers were analyzed by means of optical microscopy (OM) and scanning electron microscopy (SEM). The results obtained showed that the tungsten coating consisted of well melted particles that interconnected and were overlapping, which shows a typical lamellar microstructure. Present in the microstructure are micro pores in very small proportion at the inter-lamellar boundaries. Tests have shown that layers of W coating deposited by plasma spray in inert gas shielding at low pressure have good mechanical properties and microstructure, which in the fully enables its use in exploitation.

Keywords

• tungsten
• vacuum plasma spray (vps)
• microstructure
• interface
• microhardness
• bond strength