High temperature oxidation and hot corrosion behavior of Ti₃SiC₂- based materials

The high temperature oxidation behavior of Ti₃SiC₂ was studied from 900°C to 1200°C in air. The present results showed that scale growth obeyed a parabolic law below 1100°C, while above 1200°C it was a two-step parabolic law or linear law depending on the TiC content in Ti₃SiC₂. The oxide scale was generally composed of an outer layer of coarse-grained TiO₂ (rutile) and an inner layer of fine-grained TiO₂ and SiO₂ (tridymite) above 1000°C. A discontinuous SiO₂ "barrier" was observed within the outer coarse-grained TiO₂ layer on the samples oxidized at 1100°C and 1200°C. The TiC content in Ti₃SiC₂ is deleterious to its oxidation resistance. Ti₃SiC₂ demonstrated good hot corrosion behavior beneath Na₂SO₄ coatings, while beneath 25wt.% NaCl + 75wt.% Na₂SO₄ coatings, it showed deleterious hot corrosion behavior, suggesting that the presence of NaCl accelerated the hot corrosion of Ti₃SiC₂ materials.