Preparation Of Ultrafine WC Powders And Its Application In Wearable Coatings

The preparation of ultrafine WO₃ powders and the deoxidizing and carbonizing of WO₃ to WC were studied. Well abrasive resistant metal composite coating strengthened by ultrafine WC particles was prepared by flame thermal spray method and abrasive wear property was studied.Ultrafine WO₃ powders were prepared by colloidal chemical method using sodium tungstate, hydrochloric acid and palmityl trimethyl ammonium bromide as starting materials. The effect of concentration of reactant, mixing manner, surfactant on size, morphology and agglomeration of powders were studied, and the parameters were investigated. It was found that dropping reactants together at the same time and mechanical stirring could improve the disperse property of the particles in the solution. Keeping concentration of reactant could make electrolyte particles produce appropriate thickness of electrical double layer on colloidal particles. Mechanical force between colloidal particles decreased the chance of collision and restrain colloidal particles from growing. This contributed to formation of non-agglomerate ultrafine WO₃ powders.Ultrafine WC powders were prepared with the mixing of ultrafine WO₃ powders with carbon black by continous direct carburization process. The effect of different molar ratio of WO₃/C, reaction temperature and reaction time were studied. The powders were characterized by using several techniques such as BET, XRD, SEM, and so on. The ultrafine WC powders and the Ni-based powders were mixed. The ultrafine WC-metal composite coating was prepared by flash thermal spray method .The effect of the volume fraction of ultrafine WC on the coating preparation technique and the abrasive resistant ability were studied. The composite coating dispered with lvol% ultrafine WC particles presented the best wear resistance property and the best microhardness.