RE-Si-Al-O玻璃相对高熵稀土双硅酸盐微结构及耐CMAS腐蚀性能的影响

Influence of RE-Si-Al-O Glass Phase on Microstructure and CMAS Corrosion Resistance of High Entropy Rare Earth Disilicates

环境障涂层是高功重比航空发动机的关键技术,其目的是阻挡燃气及环境腐蚀介质的侵蚀,为陶瓷基复合材料热端部件提供有效保护。目前,高熵稀土双硅酸盐((xRE_(1/x))_(2)Si_(2)O_(7))是最具潜力的新一代环境障涂层材料。为了进一步提升高熵稀土双硅酸盐的耐高温(1500℃)CMAS(CaO-MgO-Al_(2)O_(3)-SiO_(2))腐蚀能力,本工作设计制备了一种新型高熵(Y_(0.25)Yb_(0.25)Er_(0.25)Tm_(0.25))_(2)Si_(2)O_(7)/RE-Si-Al-O(RE=Yb、Y、La)复相陶瓷。结果表明,在复相陶瓷中,RE-Si-Al-O玻璃相不仅能够包裹陶瓷晶粒,而且能够促进稀土双硅酸盐晶粒长大,减少晶界数量,使CMAS熔体的渗入通道数量减少。同时,随着RE-Si-Al-O玻璃相中稀土离子半径增大,玻璃相更易与CMAS熔盐中的Ca^(2+)离子反应,生成磷灰石相,降低CMAS熔体的活性,抑制高温CMAS熔盐对高熵稀土双硅酸盐晶粒的侵蚀,从而提高高熵稀土双硅酸盐的耐高温CMAS腐蚀能力。在1500℃腐蚀48 h后,(Y_(0.25)Yb_(0.25)Er_(0.25)Tm_(0.25))_(2)Si_(2)O_(7)/La-Si-Al-O复相陶瓷表面仍残留CMAS熔盐层,表明该复相陶瓷具有良好的耐高温CMAS腐蚀能力。该复相陶瓷的微结构设计为增强环境障涂层材料在高温CMAS环境下的长期应用提供了一种新的思路。

Environmental barrier coating(EBC)is a key material for high power-to-weight ratio aero engine,which can provide effective protection for the hot end components of ceramic matrix composites,and prevent the erosion of gas and environmental corrosive media.At present,high entropy rare earth disilicates((xRE_(1/x))_(2)Si_(2)O_(7))are the most promising next-generation environmental barrier coatings.In order to enhance the CMAS corrosion resistance of high entropy rare earth disilicates,a novel high entropy(Y_(0.25)Yb_(0.25)Er_(0.25)Tm_(0.25))_(2)Si_(2)O_(7)/RE-Si-Al-O(RE=Yb,Y,and La)multiphase ceramic was designed and prepared.The results show that the RE-Si-Al-O glass phase can not only wrap the ceramic grains,but also exist at the grain boundaries.Moreover,this multiphase ceramics can promote the growth of rare earth disilicate grains,reduce the number of grain boundaries,and decrease the number of diffusion channel of CMAS melt.As the radius of rare earth ion in the RE-Si-Al-O glass phase increases,the glass phase is more prone to react with Ca^(2+)ion in the CMAS melt,generating apatite,reducing the activity of the CMAS melt,inhibiting the erosion of high entropy rare earth disilicate grains by the CMAS molten salt,and thus improving the CMAS corrosion resistance of high entropy rare earth disilicates.After corrosion at 1500℃for 48 h,there is still a residual CMAS layer on the surface of(Y_(0.25)Yb_(0.25)Er_(0.25)Tm_(0.25))_(2)Si_(2)O_(7)/La-Si-Al-O multiphase ceramics,indicating that the multiphase ceramics have good resistance to CMAS corrosion.In conclusion,the microstructure design of this multiphase ceramic provides a new approach to improve the long-term application of EBC materials in high-temperature CMAS environments.