Preparation and properties of Ti ₃SiC ₂-based corrosion mitigation coatings for SiC _f/SiC PWR accident tolerant fuel cladding

Abstract

To enhance the resistance of SiC_f/SiC to hydrothermal corrosion in the pressurized water reactor (PWR) environment, structurally tunable Ti₃SiC₂-based corrosion mitigation coatings for SiC_f/SiC were prepared using molten salt synthesis. The influence of various process parameters like Si/Ti molar ratio in the raw materials, annealing time and annealing temperature, on the phase composition and the structure of coatings was explored. Through process control, the fabricated coatings can be either Ti₃SiC₂ monolithic structure or TiC/Ti₃SiC₂ and TiC/Ti₃SiC₂/Ti₅Si₃C_x multi-layered structures. The coatings demonstrate strong bonding to the substrate due to in-situ reaction, exhibiting tensile and shear strengths of at least 26.9 MPa and 30.8 MPa, respectively. Incorporating TiC as a transition layer further enhances the strengths to 41.3 MPa and 51.4 MPa, respectively. Monolithic Ti₃SiC₂ coatings enhance the thermal conductivity of SiC_f/SiC by 10%~12%. Notably, Ti₃SiC₂ coatings effectively protect SiC_f/SiC from hydrothermal corrosion, demonstrating an 83% strength retention rate compared to 71% in the control group after corrosion. However, the Ti₅Si₃C_x layer exhibits unsatisfactory corrosion mitigation. Ti₃SiC₂ monolithic coating has higher thermal conductivity, TiC/Ti₃SiC₂ multi-layered coating has higher bonding strength, and both have desirable resistance to hydrothermal corrosion.