摘要
目的提高热障涂层抗氧化性能,并减小二次反应区的形成。方法采用真空电弧离子镀技术在二代单晶高温合金DD32表面制备NiCoCrAlYHf(HY5)金属粘结层,分别在870℃及1000℃下进行真空扩散处理,利用电子束物理气相沉积(EB-PVD)技术制备氧化钇部分稳定氧化锆(YSZ)陶瓷层。采用扫描电子显微镜(SEM)、电子探针(EPMA)以及能谱(EDS)等测试方法,研究高温循环氧化过程中热障涂层的微观形貌、成分及扩散机制,同时计算了1、125 h氧化时间下Al元素互扩散系数。结果经过1000℃热循环、1000℃热处理的涂层氧化质量增量的绝对值较小,氧化速率常数为7.21×10-4,抗循环氧化性能较好。1100℃热处理试样,从涂层表面到基体方向Ni、Al、Cr等元素分布都比较均匀,在涂层与基体界面处,元素含量变化较为平滑。870℃热处理试样,Ni等元素质量分数分布不均,在涂层与基体界面处元素含量陡然变化,元素均质化程度低。Al元素扩散系数随着浓度的增加而增大,随着氧化时间的延长,粘结层与高温合金之间的元素扩散程度加剧,Al元素扩散系数减小。经过125h循环氧化,粘结层/基体界面出现互扩散区,互扩散区局部区域富Cr,Al含量低。循环氧化250 h后,热障涂层试样扩散区下方有拓扑密堆相TCP析出,形成二次反应区SRZ。真空扩散温度为870℃的试样,二次反应区更加明显。结论金属粘结层在1000℃下进行真空热处理可以有效提高涂层的抗氧化性能。涂层内部元素均质化程度高,Al元素扩散速率慢。同时,扩散区宽度较小,二次反应区不明显。
Objective To improve the oxidation resistance and decrease the second reaction zone (SRZ) of thermal barrier coating (TBC).Methods The bond coating of HY5 (NiCoCrAlYHf) was prepared by vacuum arc ion plating on second generation single crystal super-alloy DD32 to carry out vacuum diffusion treatment at 870 ℃ and 1000 ℃ respectively.And then YSZ was deposited on the bond coating by EB-PVD.Microstructure,composition and diffusion mechanism of the thermal barrier coating during high temperature cyclic oxidation were studied through test with SEM,EDS and EPMA.The inter diffusion coefficient of Al element in 1,125 h of oxidation was calculated.Results After thermal circulation at 1100 ℃,the absolute value of oxidation mass increment of the coating after thermal treatment at 1000 ℃ was small;the oxidation rate constant was 7.21×10^-4;and the cyclic oxidation resistance was good.For samples after thermal treatment at 1000 ℃,the distribution of Ni,Al,Cr and other elements was relatively uniform from the surface of the coating to the direction of the substrate;and the change of element content was relatively smooth at the interface between the coating and the substrate.For samples after thermal treatment at 870 ℃,the mass fraction of Ni and other elements was unevenly distributed;the element content changed abruptly at the interface between the coating and the substrate,resulting in a low degree of element homogenization.The diffusion coefficient of Al element increased with the increase of concentration.With the extension of oxidation time,the element diffusion between the bonding layer and the superalloy increased and the diffusion coefficient of Al element decreased.After 125 h of cyclic oxidation,the bonding coating/substrate interface had interdiffusion region.Local region of interdiffusion region was rich in Cr,but the Al content was low.After 250 h of cyclic oxidation,topologically dense phase TCP precipitated under the diffusion region of the thermal barrier coating sample,forming a secondary reaction
作者
杨文慧
牟仁德
YANG Wen-hui;MU Ren-de(Aviation Key Laboratory of Science and Technology on Advanced Corrosion and Protection for Aviation Material,AECC Beijing Institute of Aeronautical Materials,Beijing 100095,China)
出处
《装备环境工程》
CAS
2019年第1期7-12,共6页
Equipment Environmental Engineering
关键词
热障涂层
热处理
互扩散
二次反应区
thermal barrier coating
heat treatment
interdiffusion
second reaction zone
