Evaluation of stellite coatings by µ-PTA powder, laser, and PTA deposition processes

Abstract

This article presents comparative evaluation of microplasma-transferred arc powder deposition (µ-PTAPD), laser deposition, and plasma-transferred arc deposition (PTAD) processes for sound quality and cost-effective deposition of Stellite 6 on AISI 4130 steel substrate. Dilution, deposition thickness, microstructure, secondary dendritic arm spacing (SDAS), microhardness, and abrasive wear resistance have been used for comparative evaluation. Analysis of morphology of Stellite deposition revealed that µ-PTAPD process and laser deposition processes could produce a coating of less than 1 mm thickness having good deposition quality, smaller dilution, and SDAS as compared with PTAD process. Analysis of X-ray diffraction patterns revealed that the Stellite coatings manufactured by all three processes had a lamellar structure consisting of Co phases, chromium-rich carbides (Cr23C6 and Cr7C3), and tungsten-containing compounds (W2C). Analysis of microhardness and abrasive wear resistance found that the Stellite coatings manufactured by µ-PTAPD and laser deposition processes exhibited a lower coefficient of friction, wear volume, and higher microhardness as compared with the coating manufactured by PTAD process, this imparting them with higher abrasive wear resistance. This work proves that µ-PTAPD process has a capability to offer an economical and sustainable solution for good-quality thin coating of Stellite on metallic substrates. © 2017 Taylor & Francis.