Deposition of SiC/La2Zr2O7 multi-component coating on C/SiC substrate by combining sol-gel process and slurry

Lanthanum zirconate (La2Zr2O7) has been developed as futuristic thermal barrier coatings (TBCs) for Si-based ceramic matrix composite combustor and vane applications. The large mismatch of thermal expansion coefficient between La2Zr2O7 coating and composite substrate is a key limitation to this use of TBCs. To solve this problem, SiC/La2Zr2O7 multi-component coating has been prepared on the C/SiC composites surface by combining sol-gel process and slurry. Well-dispersed, single pyrochlore structured nanoscale La2Zr2O7 powders for coating was synthesized by sol-gel method. The as-prepared SiC/La2Zr2O7 multi-component coating was well bonded to the substrate, which might be associated with the newly formed La4.67(SiO4)3O phase, with a uniform thickness of 85.8 μm. The thermal conductivity of the C/SiC composites decreased by 12% to 28% after deposition of SiC/La2Zr2O7 multi-component coating.