Hot corrosion behavior of Ti 3SiC 2 in the mixture of Na 2SO 4–NaCl melts

Abstract

The corrosion behavior of polycrystalline Ti 3SiC 2 was studied in the mixture of Na 2SO 4–NaCl melts with various mass ratios at 850 °C. The results demonstrated that Ti 3SiC 2 suffered from serious hot corrosion attack in the mixture of Na 2SO 4–NaCl melts when the concentration of Na 2SO 4 was higher than 35 wt.%. A large amount of corrosion products spalled from specimens during the tests and obvious mass loss was observed. Hot corrosion of Ti 3SiC 2 would become severe because NaCl had lower melting-point and caused Na 2SO 4–NaCl mixture melted below 850 °C. However, when the concentration of Na 2SO 4 was lower than 25 wt.% in the mixture, a protective oxide layer (SiO 2 + TiO 2) formed on the substrate, the corrosion rate of Ti 3SiC 2 became quite slow and slight mass gain was observed, the corrosion products did not spall from substrate at 850 °C. The microstructure and phase composition of the corroded samples were investigated by SEM/EDS and XRD.