LASER-INDUCED SURFACE ALLOYING OF AL2O3 CERAMICS WITH ZRO2-TIO2 POWDERS

Al2O3 ceramics containing low and high porosity, respectively, were re melted and alloyed with ZrO2 and TiO2 in varying mol% by using CO2 las er radiation. The resulting microstructures were analysed using electr on microscopy, energy-dispersive X-ray spectroscopy (EDX) and X-ray di ffraction techniques. Composite surface layers of a thickness of about 200 mum were obtained which showed distinctly reduced porosity and ho mogeneously distributed ZrO2- and TiO2-rich phases. As a result of the alloying, the tendency for crack formation and grain growth was subst antially reduced in the Al2O3 ceramics during laser treatment. Hardnes s of the structures was lowered, but resistance to cracking under the mechanical action of a sliding diamond (scratch test) was substantiall y enhanced by adding ZrO2 and TiO2 to the alumina. This study has show n that microstructure of a surface layer can be effectively modified o n oxide ceramics by laser-induced alloying. Laser treatment offers som e advantages over conventional methods of ceramic processing and can b e used for many practical applications.