Soldering techniques are often used to avoid difficulties which arise in accurately casting large-span dental bridges. To avoid this problem, subunits are cast and assembled by soldering. A detailed understanding of the alloy/ solder interface does not exist. There are conflicting reports on alloy/solder epitaxy and on the formation of interfacial phases. This study will correlate the mechanical properties of several dental alloy/solder interfaces with the microstructures observed by cross-sectional transmission electron microscopy (XTEM). Five alloys with varying amounts of Au and Pd will be joined using simulated preceramic and postceramic soldering techniques. The alloy/ solder strength will be measured using threepoint flexural bending. The microstructure will be examined using XTEM. The results of this study should provide a solid experimental basis for the nature of the alloy/solder interface and enable materials scientists to tailor alloy/solder combinations to optimize their important parameters. Phase II of this program will apply the principles learned in Phase I to the development of new alloy/solder combinations. In addition, the techniques developed under Phase I will be extended to other dental materials systems, for example, the ceramic/metal interface.National Institute of Dental Research (NIDR)
