Corrosion behavior and strength degradation of Ti3SiC2 exposed to a eutectic K2CO3 and Li2CO3 mixture

The corrosion of polycrystalline Ti3SiC2 was studied in the eutectic Li2CO3 (68 at.%) and K2CO3 (32 at.%) Mixture at 650-850degreesC. Ti3SiC2 exhibited better corrosion resistance at 650 degreesC. However, the mass loss was fast when temperature was above 700 degreesC. It was demonstrated that the surface chemical reaction-controlled shrinking core model could be applied to describe the relationship between the degree of the corrosion and reaction time for the corrosion of Ti3SiC2 in the 700-850 degreesC temperature range. The corresponding apparent activation energy was 206 kJ/mol. Corrosion resulted in roughness of specimen surface. The fracture strength of the corroded samples was evaluated by a three-point bending test. The results showed that the degradation of the fracture strength was about 25% of the original values for the corroded specimens tip to 10% weight loss. The mechanism of the strength degradation was discussed based on the analysis of the microstructure and composition of the corroded sample. (C) 2003 Elsevier Science Ltd. All rights reserved.