Surface softening and hardening of WC-Co using pulsed laser irradiation

The surface of cobalt-containing tungsten-carbide was treated using a pulsed Nd: YAG laser beam under atmospheric conditions in order to control its surface hardness by means of surface diffusion or concentration of cobalt. Elemental analyses of the treated surfaces revealed a laser fluence of 0.25 J/cm2 to be the most suitable condition for the concentration of cobalt and the removal of surface contaminants, such as hydrocarbons and oxygen gas, without damaging the surface. At this laser fluence, the concentration of cobalt was reduced close to the center of irradiation but increased in the area surrounding the irradiation center. This concentration of cobalt resulted in a softening of the WC-Co surface by over 10% compared to the non-treated surface, as measured by a Knoop hardness tester under a load of 9.8 × 10− 2 N.