Preparation and properties of Ti3SiC2-based corrosion mitigation coatings for SiCf/SiC PWR accident tolerant fuel cladding

To enhance the resistance of SiCf/SiC to hydrothermal corrosion in the pressurized water reactor (PWR) environment, structurally tunable Ti3SiC2-based corrosion mitigation coatings for SiCf/SiC were prepared using molten salt synthesis. The influence of various process parameters, such as Si/Ti molar ratio in raw materials, annealing time, and annealing temperature, on the phase composition and the structure of the coatings was explored. Through the process control, the fabricated coatings can be either Ti3SiC2 monolithic structure or TiC/Ti3SiC2 and TiC/Ti3SiC2/Ti5Si3Cx multilayered structures. The coatings demonstrate strong bonding to the substrate due to in-situ reaction, exhibiting tensile and shear strength of at least 26.9 and 30.8 MPa, respectively. Incorporating TiC as a transition layer further enhances the tensile and shear strength to 41.3 and 51.4 MPa, respectively. Monolithic Ti3SiC2 coatings enhance the thermal conductivity of SiCf/SiC by 10%-12%. Notably, Ti3SiC2 coatings effectively protect SiCf/SiC from hydrothermal corrosion, demonstrating an 83% strength retention rate compared to 71% in the control group after corrosion. However, the Ti5Si3Cx layer exhibits unsatisfactory corrosion mitigation. The Ti3SiC2 monolithic coating has higher thermal conductivity, TiC/Ti3SiC2 multi-layered coating has higher bonding strength, and both have desirable resistance to the hydrothermal corrosion.