Development of slurry-based Ca0.5Sr0.5Zr4(PO4)(6) (CS-50) coatings for SiCin fossil energy applications

Coatings of Ca,,Sr,,Zr,(PO,), (CS-50), an ultra-low thermal-expansion mater ial, have been successfully developed to protect SiC-based materials from s ulfate salt corrosion. The coatings were applied to fiber-reinforced, SiC-m atrix composite heat exchanger tubes and clay-bonded SIG. Aqueous slurries were prepared and applied to the SiC substrates. One coating process for he at exchanger material substrates, consisted of mechanically dipping the sam ples in a slip. A spin-coating process has also been developed that produce d thin, non-obstructing coatings for hot-gas filter substrates. The thermal shock and corrosion resistance of coated parts were evaluated, and prelimi nary results are encouraging for the use of CS-50 as a protective coating.