Optimizing the properties of nano WC-10Co-4Cr HVOF coatings by using RSM

Abstract

One of the limitations of using tungsten carbide nanoparticles in the HVOF coating method is decarburization of these particles during the coating operation. These unwanted changes lead to severe drop in coating properties. Optimized effective HVOF parameters is one of the solutions to control this issue. In this article, HVOF effective parameters (oxygen flow rate, powder flow rate and spray distance) were optimized using RSM (response surface methodology) to control this phenomenon and achieve optimum hardness, deviation of hardness and bending strength. The results showed that oxygen flow rate has the greatest effect on hardness and hardness deviation, while spray distance has the most influence on bending strength. In order to obtain optimal properties, in oxygen flow rate: 858 lit/min, distance: 34 cm and powder flow rate: 82 gr/min, the highest hardness (>1270HV0.1) and strength (cracking bending angle <80 degrees) and the lowest hardness deviation (<17HV0.1) reached with more than 92% probability. The validity of the results was confirmed by using XRD analysis. The validation results confirmed the coating properties and RSM model.