Research in this laboratory on glass-to-metal bonding has resulted in a theory of chemical bonding which has been consistent with experimental results and has met with general agreement. The research performed on this project to date indicates that this theory can be applied to multicomponent alloy systems as well if an understanding of the nature and kinetics of the reactions that occur within the system exists. The ongoing studies to develop this understanding have indicated that overall reactions are complex and that additives to the alloys affect their reactivity with glass. A number of reactions can take place involving chromium and other active elements depending on the compositions of both the alloys and glasses. The objectives of this research are: 1) to determine which elements (designated as active) in a multicomponent nickel-chromium based alloy system, including dental alloys are responsible for contributing to the development of a bonding mechanisms and good adherence; and 2) to identify the reactions, their mechanisms and conditions under which they occur that lead to the development of good adherence. Coating and sessile drop experiments under oxidizing conditions will be made to study wetting and prepare specimens for interfacial reaction studies. Cross-sections will be analyzed with a SEM-Kevex and an electron microprobe. Modern surface analytical tools like Auger/ESCA/SIMS will be used for the analysis of the interface with slow sputtering of surfaces parallel to the interface. Experimental and commercial alloys will be subject to short time oxidation studies to determine characteristics and kinetics of the oxidation of alloys with different alloying elements. A new, simple method for adherence measurement based on identation fracture is proposed. The basic method has been developed in our laboratory and provides a quantitative measure of the interface fracture resistance (adherence) with the advantage of simplicity and reproductibility.
| Pask, J A; Tomsia, A P (1988) Oxidation and ceramic coatings on 80Ni20Cr alloys. J Dent Res 67:1164-71 |
| Tomsia, A P; Pask, J A (1986) Chemical reactions and adherence at glass/metal interfaces: an analysis. Dent Mater 2:10-6 |
