Reactions of titanium with silicate or borate glasses and their role in interfacial adhesion.

摘要

Scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and contact angle measurement were used to understand the mechanism for the formation of titanium to silicate (or borate) glass seals which are used in aerospace and biomedical applications. The XPS analysis of titanium film deposited in-situ on glass substrates indicates that the initial stages of Ti-silicate glass and Ti-borate glass reactions are qualitatively similar. An intermetallic titanium silicide or titanium boride phase forms immediately after Ti is deposited on the glass even at room temperature. The oxides of titanium form at a later stage of reaction between the intermetallic phase and the glass. Inspite of the similarity of initial reactions, the interface morphology between titanium and silicate/borate glass is different in the bulk diffusion couples prepared at 700;The present work demonstrates that the reported higher strength of Ti-borate glass seals compared to Ti-silicate glass seals is due to (a) mechanical interlocking of TiB precipitates with Ti and (b) higher values of the thermodynamic work of adhesion at Ti-borate glass interfaces. Pask's theory of adhesion is not applicable for the present Ti-glass systems. Finally, recommendations are also developed for predicting good adhesion in metal-glass seals on the basis of metal-glass forming cation-oxygen (M-X-O) ternary phase diagrams, associated activity diagrams and diffusion information.