Laser Surface Treatment of Ceramic-Metal Composite Coatings

摘要

Ceramic-metal Cr_3C_2-NiCr composite coatings obtained by high velocity oxy fuel thermal spraying (HVOF) lack of wear and corrosion resistance due to their high porosity. One solution to this problem can be achieved through the irradiation of the coating by means of a high power laser in order to melt a thin superficial layer and seal the coating. A Nd: YAG laser has been used to irradiate samples under those conditions where the best sealing results are obtained. The properties of either untreated and laser treated coatings have been investigated through scanning electron microscopy, x-ray diffractometry and profilometry. These analyses have revealed that the laser treatment induces important changes in the surface of the irradiated samples leading to a decrease in roughness, the elimination of porosity and an increase in hardness. Unfortunately, the treatment also promotes the presence of cracks.