摘要
目的阐明56%(质量分数)氧化钇稳定氧化锆(56YSZ)涂层1350℃条件下CMAS(钙镁铝硅酸盐)腐蚀行为,分析腐蚀产物及其演变规律,揭示等离子喷涂56YSZ涂层高温CMAS腐蚀机理。方法利用大气等离子喷涂方法制备56YSZ涂层,在1350℃条件下对表面涂敷CMAS(33Ca O-9Mg O-13Al O1.5-45SiO_(2))的56YSZ涂层进行CMAS腐蚀试验。结合X射线衍射仪(XRD)、扫描电镜(SEM)和能谱分析仪(EDS),表征经1350℃腐蚀不同时间后涂层物相结构与微观形貌,以分析1350℃条件下56YSZ涂层CMAS腐蚀行为。结果在1350℃高温环境下,涂层CMAS腐蚀速率随时间延长呈明显的下降趋势,8 h后涂层CMAS腐蚀速率最低(0.50μm/h),且经过50 h腐蚀后CMAS腐蚀深度由(150.9±11.0)μm增至(172.5±18.3)μm。在腐蚀初期,CMAS熔体快速渗透,与涂层反应生成了磷灰石相;然而,随着CMAS熔体中Si^(4+)/Al^(3+)比值逐渐降低,熔体与涂层反应生成了石榴石相,且c-ZrO_(2)包裹磷灰石相与石榴石相形成了致密的保护层;最终涂层腐蚀区反应产物主要为c-ZrO_(2)、磷灰石相及石榴石相。结论56YSZ涂层在1350℃条件下展现出优异的抗CMAS腐蚀性能,腐蚀反应生成的磷灰石相、石榴石相以及c-ZrO_(2)共同组成了致密保护层,有效阻滞了CMAS熔体的腐蚀渗透,并快速消耗CMAS熔体活性元素,在56YSZ涂层抗腐蚀过程中起到了积极作用。
The CMAS(calcium-magnesium-alumino-silicate)corrosion behavior of the free-standing 56 wt.%yttria stabilized zirconia(56YSZ)coatings fabricated via atmospheric plasma spraying process at 1350℃is investigated and its corrosion mechanism is also elucidated in the research.Firstly,the mixture powders composed of 33%CaO,9%MgO,13%AlO1.5,and 45%SiO_(2) are uniformly mixed and coated to the surface of as-deposited coatings,and then the coated samples are subject to high-temperature exposure in a muffle furnace at 1350℃for different times.After corrosion at 1350℃for different times,the phase composition and microstructure of the corrosion products are characterized by X-ray diffraction(XRD)and scanning electron microscopy(SEM)equipped with an energy dispersive X-ray spectroscopy(EDS).As a result,the corrosion depth of 56YSZ coating is increased rapidly from(57.6±6.7)μm to(150.9±11.0)μm with the prolonged exposure time after being exposed at 1350℃,and the final corroded layer with the thickness of(172.5±18.3)μm is achieved after corrosion for 50 h.It is easy to note that a positive relationship between the depth of the corroded layer and the corrosion duration is obtained.During the initial stage of corrosion,the CMAS mixture powders are deposited on the coating surface and gradually melted with the increasing temperature,which could be infiltrated into the coating through the presence of cracks and pores.As we all know,the CMAS corrosion rate is directly related to the viscosity of the melt and its element content.In this corrosion stage,the CMAS melt would quickly react with Y^(3+)to form an apatite phase,and the corrosion rate is also increased,which is mainly attributed to the richest CMAS melt and its highest viscosity.However,the viscosity of the CMAS melt is then reduced under the combined effect of the decreasing SiO2/CaO ratio and the permeate of Y^(3+).With the reaction proceeding,the apatite phase consumes large amounts of Si4+and Ca^(2+),and lower Si^(4+)/Al^(3+)ratio in the CMAS melt creates favorable conditions for the formation of garnet,resulting in the decrease of the corrosion rate from 28.8μm/h to 15.9μm/h.After corrosion for 4 hours,it is observed that the two dense layers appear in the inner region and the outer region of the corrosion layer.Based on the element distribution,the outer region of the corrosion layer is mainly consisted of c-ZrO_(2) and the apatite phase,while the c-ZrO2 and the garnet phase present in the inner region.Due to the formation of dense layers,the CMAS melt penetration is blocked.When the corrosion time is prolonged to 8 hours,the elements in the melt are nearly consumed and the corrosion rate is significantly reduced to 0.5μm/h.At this stage of corrosion reaction,the appearance of element diffusion and segregation is present in the corrosion products,and large-scale pores appear in the corrosion layer,while a thin calcium-rich layer is formed on the surface.Consequently,the CMAS corrosion behavior of plasma-sprayed 56YSZ coating could be divided into three stages,including the initial rapid corrosion dominated by the thermal penetration of CMAS melt,followed by the formation of a dense layer composed of apatite and garnet phases via thermochemical reactions,and the arreargae of the CMAS corrosion resulting in the slowly increase of corrosion layer.The primary phases in the CMAS corrosion products are found to be c-ZrO_(2),apatite,and garnet.It is concluded that the 56YSZ coating could be considered to be a promising candidate material for thermal barrier coatings(TBCs)with exceptional CMAS corrosion resistance.
作者
胡延浩
范习之
黄文质
赵凯睿
毛卫国
HU Yanhao;FAN Xizhi;HUANG Wenzhi;ZHAO Kairui;MAO Weiguo(School of Materials Science and Engineering,Changsha University of Science&Technology,Changsha 410114,China;Science and Technology on Advanced Ceramic Fibers&Composites Laboratory,College of Aerospace Science and Engineering,National University of Defense Technology,Changsha 410073,China;School of Materials Science and Engineering,Dalian University of Technology,Liaoning Dalian 116024,China)
出处
《表面技术》
北大核心
2025年第12期61-71,共11页
Surface Technology
基金
国家自然科学基金(52371087)
湖南省自然科学基金(2025JJ20043)。
关键词
高氧化钇稳定氧化锆
CMAS腐蚀
热障涂层
腐蚀机理
热渗透
大气等离子喷涂
high yttria stabilized zirconia
CMAS corrosion
thermal barrier coating
corrosion mechanism
thermal penetration
atmospheric plasma spraying
