Electrical contact behavior of Ag-SnO2-In2O3 contact materials prepared via pressurized powder internal oxidation

Abstract

In this study, the pressurized powder internal oxidation method is used to conduct internal oxidation experiments on Ag-8.1Sn-3.83In alloy powders in a pure O2 environment. Through thermodynamic and kinetic analyses of the oxidation process, the optimal oxidation temperature is determined. Additionally, a Richardson-Jeffes plot is generated, and ΔGpO2T are presented on the same thermodynamic diagram for convenient examination. The phase compositions, morphologies, and microstructures of the samples before and after oxidation are analyzed using X-ray diffraction, scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS), and optical microscopy. Additionally, a simultaneous analysis of thermogravimetric and differential scanning calorimetry curves is performed using a synchrotron analyzer. The internal oxidation mechanism of the Ag-8.1Sn-3.83In alloy powders is determined. The oxidized Ag-8.1Sn-3.83In alloy powders are then processed into Ag-SnO2-In2O3 contact materials. Subsequently, the electrical performance of the Ag-SnO2-In2O3 contact materials is tested under DC 24 V/15 A conditions. The results indicate an average fusion welding force of 28.06 cN, an average arcing time of 8.17 ms, an average arcing energy of 520.57 mJ, and an average contact resistance of 0.055 mΩ. SEM/EDS analysis of the electrical erosion reveals that the material transfer direction is from the cathode to the anode. Furthermore, the electrical erosion behavior of the Ag-SnO2-In2O3 contact material is analyzed. By combining the results with the results of open–close electrical contact performance testing, the electro-erosion mechanism of Ag-SnO2-In2O3 contact materials prepared via pressurized powder internal oxidation of Ag-Sn-In alloy powders is clarified. This research provides theoretical support for the preparation of Ag-SnO2-In2O3 contact materials.