High temperature oxidation of higher manganese silicides

Abstract The oxidation kinetics and mechanisms of higher manganese silicides (HMS) MnSi1.75, MnSi (1.75-x)Gex, MnSi(1.75-x)Alx (with x = 0.005 and 0.01)were studied and the effects of densification methods and dopant concentration discussed. Oxidation experiments were conducted using thermogravimetry (TGA), while post characterization with X-ray Photoelectron Spectroscopy (XPS) and Scanning Electron Microscope (SEM) showed that spark plasma sintering (SPS) is a better densification method than hot pressing (HP). Except for undoped HMS, HMS doped with 0.5at% Ge had the lowest oxidation rate. Stable formation of a SiO2 protective layer was the main reason for improved oxidation resistance in air in the temperature range 200 °C-500 °C.