Abstract: The present research shows that the composite with Ti (or its alloys) as a substrate and commercial porcelain as its coating has been proved to be
quite effective to resolve bio-compatibility problem since the porcelain, which contains mainly Al₂O₃, SiO₂, K₂O, Na₂O, possesses best bio-
compatibility with human tissues. Moreover, the above composite adding a thin layer of Si₃N₄ between the Ti substrate and porcelain coating has
been proved to be even more effective to resolve present problem due to the adhesion between the substrate and the porcelain coating quite strengthened.
These composites are successfully applied to the present application and may open new application fields since the problems have been effectively resolved. The present investigation not only gives the chemical composition, the
technical process and the performance of the composites, but also gives their microstructure details.

Key words: Ti-alloy-ceramic interface, Si_3N_4 coating,electron microstructure