等离子喷涂改性YSZ涂层耐熔融玻璃腐蚀机制

Molten glass corrosion resistance mechanism of plasma spray-modified YSZ coating

采用Al_(2)O_(3)、TiO_(2)掺杂改性8%Y_(2)O_(3)-ZrO_(2)(质量分数,YSZ)陶瓷粉末,通过等离子喷涂制备Al_(2)O_(3)-TiO_(2)-Y_(2)O_(3)-ZrO_(2)(AT+YSZ)热障涂层,1200℃,保温2 h,对两种涂层进行熔融玻璃腐蚀试验。采用扫描电子显微镜(SEM)、X射线衍射仪(XRD)、维氏显微硬度分析仪对AT+YSZ涂层及YSZ涂层的基本性能进行对比分析。结果表明:AT+YSZ涂层截面的层状结构更为明显,与纯YSZ涂层相比,孔隙率从20.04%(YSZ)降低至14.25%(AT+YSZ),平均显微硬度从577 Hv(YSZ)提高到920 Hv(AT+YSZ);经熔融玻璃腐蚀后,AT+YSZ涂层没有出现玻璃溶液渗入现象,YSZ涂层则出现熔融玻璃渗入且涂层表面熔解现象。1200℃,AT+YSZ涂层中的Al^(3+)扩散至熔融玻璃层中,并与Ca^(2+)、Al^(3+)、Si^(4+)生成高熔点的钙长石(CaAl_(2)Si_(2)O_(8))相。同时,有少量的MgSiO_(3)晶相生成。Al_(2)O_(3)-20%TiO_(2)(质量分数,AT20)掺杂YSZ不仅提高了涂层的物理性能,还改变了熔融玻璃腐蚀下涂层的热化学反应过程。钙长石相和MgSiO_(3)晶相提高了涂层的致密度,减缓了熔融玻璃对涂层的渗入,提高了涂层耐熔融玻璃腐蚀性能。

Al_(2)O_(3)-TiO_(2)-Y_(2)O_(3)-ZrO_(2)(AT+YSZ)thermal barrier coating was prepared by plasma spray,using 8%Y_(2)O_(3)-ZrO_(2)ceramic powder which was modified by Al_(2)O_(3)and TiO_(2).The molten glass corrosion test of the two coatings was performed at 1200°C for 2 h.Scanning electron microscopy(SEM),X ray diffraction(XRD)and Vickers hardness test were used to study the intrinsic properties of the AT+YSZ and YSZ coatings.The results showed that the AT+YSZ coating possesses a clear layered structure compared with the YSZ coating.The porosity of the coating decreased from 20.04%(YSZ)to 14.25%(AT+YSZ),and the average microhardness increased from 577 Hv(YSZ)to 920 Hv(AT+YSZ).After molten glass corrosion test,the molten glass could not infiltrate into the AT+YSZ coating,but it infiltrated into the YSZ coating.The surface of YSZ coating was melted.At 1200℃,Al^(3+)of the AT+YSZ coating diffused into the molten glass,and reacted with Ca^(2+),Al^(3+)and Si^(4+)to form a anorthite(CaAl_(2)Si_(2)O_(8))phase with high melting point,while a small amount of MgSiO_(3)crystal phase was formed.Al_(2)O_(3)-20%TiO_(2)-doped YSZ not only improves the physical properties of the coating,but also changes the thermochemical reaction process of the coating upon molten glass corrosion.The anorthite phase and the MgSiO_(3)crystal phase increase the density of the coating,retard the infiltration of molten glass into the coating,and improve the resistance of the coating to molten glass corrosion.