Wear Resistance of Post Heat Treated HVOF Coatings Based on Cermet - Nickel Based Alloys Mixture

Published in: Engineering for a Smarter Planet: Innovation, ITC, and Computational Tools for Sustainable Development: Proceedings of the 9th Latin American and Caribbean Conference for Engineering and Technology
Date of Conference: August 3-5, 2011
Location of Conference: Medellin, Colombia
Authors: Linda Gil
Maria Rodriquez
Refereed Paper: #320

Abstract

The aim of the present work was studied the influence of both the chemical composition and the post heat treatment on the wear resistance of composite coatings deposited by using HVOF JP-5000 gun onto AISI 1020 steel substrate. For such a purpose, prior to deposition, the NiCrBSiWFe alloy powder was mechanically mixed with different amounts of WC-12%Co powder in order to conform three coatings having the following composition: 100% NiCrBSi; 50%NiCrBSi + 50 % (WC-12%Co) and 30% NiCrBSi +70 % (WC-12%Co). An oxyacetylene flame was used to perform the post heat treatment, whose duration was of 300 seconds. The evaluation of the wear resistance of these coatings was achieved by means of abrasion wear tests according to ASTM G65-C. The hardness of the coating was determined by means of Vickers indentation using a load of 300 g. A detailed study of the wear track was carried out by Scanning Electron Microscopy (SEM) combined with Energy Dispersive X-ray microanalysis (EDX) in order to provide information of the wear mechanisms. The results have shown that the wear resistance increases with the increase of the WC-Co amount in the powder mixture. However, this increase is more significant once the post heat treatment was performed, as consequence to both the precipitation hardening, which takes place in the nickel matrix ensuring a more uniform particles distribution, and to a considerable decrease in the porosity.