CMAS Hot Corrosion Behavior Of Si/?Er₂SiO₅,Er₂Si₂O₇?Thermal Barrier Coatings On C_f/SiC Surface

Carbon fiber reinforced silicon carbide ceramic matrix composite?Cf/SiC?as a kind of hot end material of potential,It is considered to be extremely developed in the fields of aerospace,weaponry and other fields.However,when the working temperature is higher than 1200°C,the atmospheric environmental deposits?CMAS?will melt and corrode the hot end parts,which greatly restricts the development prospect of Cf/SiC.In this thesis,we use Er₂SiO₅,Er₂Si₂O₇ rare earth silicate ceramics as coating materials,and study the corrosion behavior of CMAS on two rare earth lanthanum silicates.The Er₂SiO₅,Er₂Si₂O₇ powder required for the test was prepared by a solid phase synthesis method,and the powder was spray-dried and then subjected to high-temperature sintering bulk preparation.Er₂SiO₅,Er₂Si₂O₇ ceramic coating was prepared on the surface of Cf/SiC substrate by atmospheric plasma spraying.Then the corrosion behavior of CMAS on yttrium silicate blocks and coatings was studied.The high temperature anticorrosion test of rare earth erbium silicate block by CMAS found that Er and Si elements in Er₂SiO₅ and Er₂Si₂O₇ were dissolved into CMAS due to the good wettability of CMAS to rare earth lanthanum silicate.Then the Ca₂Er₈?SiO₄?₆O₂ apatite phase was precipitated,which has the effect of blocking CMAS from further attacking the coating.we found that Er₂Si₂O₇produces faster Ca₂Er₈?SiO₄?₆O₂ apatite phase than Er₂SiO₅ after reaction with CMAS.The high temperature corrosion test of rare earth cerium silicate coating by CMAS showed that the depth of CMAS penetration of Er₂SiO₅ coating was only5?m after 8h corrosion.After 48h corrosion,the CMAS penetration depth of the unshed part was about 20?m.After CMAS corrosion of the Er₂Si₂O₇ coating for48h,the CMAS penetration depth was approximately 200?m.Almost penetrates the entire coating.The Er₂SiO₅ coating exhibits excellent CMAS resistance compared to the Er₂Si₂O₇ coating.In the process of CMAS erosion two rare earth lanthanum silicate coatings.CMAS reacts rapidly with Er₂SiO₅ to form a dense Ca₂Er₈?SiO₄?₆O₂ apatite phase reaction layer,which blocks pores and microcracks on the surface of the coating and can effectively prevent further penetration of CMAS.The reaction between CMAS and Er₂Si₂O₇ is very slow.With the extension of time,CMAS will completely react with Er₂Si₂O₇ coating.The Ca₂Er₈?SiO₄?₆O₂ apatite phase reaction layer is not dense,and the anti-CMAS corrosion corrosion effect is poor.