Laser gas assisted treatment of tungsten carbide tile surface

In order to enhance structural integrity of sintered tungsten carbide tiles, a laser gas assisted melting of tungsten carbide surface is carried out. Metallurgical changes, in the surface region, are examined by using optical and electron scanning microscopes, energy dispersive spectroscopy, and X-ray diffraction. Microhardness and fracture toughness of the laser treated layer are obtained from the indentation data. Residual stress formed at the treated surface is determined through the X-ray diffraction technique. It is found that the treated surface is free from large scale asperities. Microhardness increases at the surface significantly because of formation of lamellar and acucilar morphology, which compose of WC-W2C composite in the dense layer. Fracture toughness of the treated surface reduces considerably due to microhardness enhancement at the surface. Residual stress in the surface vicinity is compressive, which is in the order of -2.1 +/- 0.06 GPa. (C) 2013 Elsevier B.V. All rights reserved.