Wear resistance of cermet coatings deposited by hvof post heat treated

The aim of the present work was to study the influence of chemical composition and post heat treatment on the wear resistance of cermet (ceramic metallically) coatings deposited by the process of High Velocity Oxy-Fuel (HVOF). For such purpose, a NiCrBSiWFe alloy was chosen which was mixed mechanically with WC-12%Co powders to form three coatings with the following proportions: 100 % of alloy NiCrBSiWFe (100NiCr), 50%NiCrBSi + 50 % WC-12%Co (50-50) and 70 % WC-12%Co + 30%NiCrBSi (70-30). The feeder powders were deposited on an AISI 1020 steel substrate by using a JP-5000 gun. An oxyacetylene flame was used to perform the post heat treatment. The evaluation of the resistance to wear for these coatings was achieved by means of the test ASTM G65-A, B y C. The microstructure and chemical composition of the coatings as well as the wear surfaces were evaluated by means of Optical Microscopy (MO) and Electronics Microscopy (MEB) coupled with an EDAX DX4 energy dispersive X-Ray spectrometer (EDS). The study showed that the resistance to abrasion wear increased with the increase of WC-Co particles in the mixture WC-Co-NiCrBSiWFe; nevertheless, the more significant increase is due to the post heat treatment which was attributed to the precipitation hardening of the nickel s matrix and to the better cohesion and better distribution of the second phase particles in the coating.