Heat Treatment of Soldered Joints in Dental Casting Gold Alloysan Electron Microprobe Analysis

Abstract

Samples of gold soldered assemblies from three different dental casting gold alloys were subjected to various homogenizing heat treatments. The distribution of available alloy components in the region of the gold-solder junction was investigated using electron-probe micro-analysis. An extensive statistical treatment of the data was performed. Concentration differences between casting alloy and solder alloy were not levelled out to any great extent unless after prolonged heat treatment (3 hours) for one of the three alloys. However, this heat treatment caused grain growth and an increased amount of microporosities in the region of the joint. In the soldered assemblies from two of the three casting alloys microphases with a composition different from the original alloys appeared at the gold-solder junction after heat treatment. The results show that homogenizing heat treatment of gold soldered assemblies should not be performed as a routine.