HIGH TEMPERATURE INTERACTIONS IN PLATINUM/ALUMINA SYSTEM

摘要

There is increasing demand for hermetic metal/ceramic bonds for application in biomedical engineering, in particular for use in neurostimulating prosthetic devices such as, cochlear implants, muscular stimulators and retinal prosthesis. Platinum/Alumina bonds are particularly interesting because of the proven biocompatibility of the two materials and their strong bonding. Yet, the true nature of their bonding is not clear. Platinum/alumina interactions in different atmosphere (i.e. air and hydrogen) and different temperatures were studied by means of high temperature X-ray diffraction, SEM and EDS analyses, to better understand the interfacial reactions and bonding mechanism. It was observed that upon heating the platinum/alumina system in the reduced atmosphere tetragonal Pt_3Al formed in low temperature and transformed to cubic structure at higher temperatures. In addition to that, at temperatures above 1500 °C alumina could migrate and encapsulate the platinum particles, with particle migration mechanism.