Slurry erosion resistance of thermally sprayed Nb2O5 and Nb2O5+WC12Co composite coatings deposited on AISI 1020 carbon steel

Niobium pentoxide (Nb2O5) has excellent physicochemical properties regardless of the processing technology. The interest in its application in several fields has increased, especially in corrosive environments. However, when higher wear resistance is required, this material shows poorer results when compared to carbide base metals. In this work, the erosive wear resistance of thermally sprayed Nb2O5 coatings with and without carbide addition was evaluated. 500 mu m thick coatings of Nb2O5 and Nb2O5 + 25% WC12Co were deposited onto AISI 1020 steel by flame spray. The coatings were characterized in the cross section by SEM/EDS techniques. Microhardness (HV0.05) and fracture toughness (KIC) measurements by the Vickers indentation toughness test (VIT) technique were performed on the cross section of the coatings. Erosive wear resistance was determined using a container tribometer with erosive mixing at a particle velocity of 9.33 m/s and 90 degrees particle incidence angles. A nonparametric Mann-Whitney statistical analysis was performed on the results, considering a p significance level of 0.05. The addition of 25% WC12Co to the Nb2O5 increased the microhardness and fracture toughness of the coating. Nb2O5+ WC12Co composite coatings showed higher resistance to erosive wear, showing 81 +/- 9 mg mass loss, 51% lower than the Nb2O5 coating (157 +/- 6 mg).