Abstract
The purpose of the present study is to investigate the influence of critical HVOF spray parameters on mechanical properties of WC–12Co coatings obtained from nanophased powder used as feedstock material. A Taguchi design of experiments approach was used for the selection and optimization of process parameters and coating properties. An L9 table was used for the evaluation of the effect of spray distance, oxygen/fuel ratio, gun traverse speed and feed rate on coating microhardness, adhesion strength, porosity and deposition efficiency – thickness. Results show clearly that each parameter affects in a different way and percentage each property. Furthermore, the comparison of XRD data with a conventional WC–12Co coating indicates that the nanostructure of the initial powder is maintained in the coating, whereas in the conventional one the formation of W2C phase is evident. Finally, fretting tests show similar behavior in terms of friction coefficient, but a significant improvement regarding wear resistance in the case of the nanophased coating.
