Internal-oxidation kinetics of ag-cd alloys

Abstract

The oxidation kinetics of the Ag-Cd alloys with different Cd contents in mass fractions (9.5, 11, 12 and 16) % at (670, 750 and 795) degrees C during the production of Ag-CdO electrical-contact materials was investigated. It was found that the internal oxidation of the investigated Ag-Cd alloys generally follows the parabolic-rate law for all the applied oxidation times (5, 9.5, 20.5, 36 and 48) h. The parabolic-rate-law constant for the measured oxide-thickness gain was evaluated at every examined temperature and the Arrhenius-type equations were determined in order to describe the temperature dependence of the rate constants. Microstructures of the obtained Ag-CdO electrical-contact materials were investigated using a SEM-EDS analysis and the microstructure of a sample produced under the optimum process conditions is illustrated with the corresponding micrographs and chemical compositions.