Laser-induced surface alloying of Al 2O 3 ceramics with ZrO 2TiO 2 powders

Abstract

Al 2O 3 ceramics containing low and high porosity, respectively, were remelted and alloyed with ZrO 2 and TiO 2 in varying mol% by using CO 2 laser radiation. The resulting microstructures were analysed using electron microscopy, energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction techniques. Composite surface layers of a thickness of about 200 μm were obtained which showed distinctly reduced porosity and homogeneously distributed ZrO 2- and TiO 2-rich phases. As a result of the alloying, the tendency for crack formation and grain growth was substantially reduced in the Al 2O 3 ceramics during laser treatment. Hardness of the structures was lowered, but resistance to cracking under the mechanical action of a sliding diamond (scratch test) was substantially enhanced by adding ZrO 2 and TiO 2 to the alumina. This study has shown that microstructure of a surface layer can be effectively modified on oxide ceramics by laser-induced alloying. Laser treatment offers some advantages over conventional methods of ceramic processing and can be used for many practical applications.