温度梯度热循环下纳米7YSZ陶瓷层结构演变
发布时间：2019-05-31 18:28
【摘要】：目的采用低温超音速等离子喷涂(LT-HVOF)在镍基高温合金基体(K417)上制备了NiCoCrAlYTa粘结层,使用大气等离子喷涂(APS)在粘结层上制备了纳米7%Y_2O_3-ZrO_2(7YSZ)陶瓷涂层,以获得温度梯度热循环下纳米陶瓷层的结构演变机制。方法通过燃气热冲击实验仪对热障涂层模拟真实服役条件下温度梯度热循环的工作环境,采用一维稳态热传导模型计算了热障涂层中各涂层界面的温度,探讨了在热驱动作用下等径晶粒和非等径晶粒的扩散长大机制。结果热循环次数为40次时,涂层近表面出现了烧结致密化现象,而陶瓷层底部涂层保持原来的结构。热循环次数增加到460次时,整个陶瓷层断面都发生了烧结致密化现象。结论温度是涂层烧结致密化的主导因素。涂层中当等大晶粒接触形成弯曲颈时,由于弯曲颈只受水平方向静压力作用,晶粒中原子扩散速率慢,导致晶粒长大速率较慢;而当非等大晶粒接触形成弯曲颈时,在晶粒接触弯曲颈处存在一偏大晶粒方向的剪切力,其导致晶粒向弯曲颈扩散速率增加,晶粒长大速率较快。
[Abstract]:Objective to prepare NiCoCrAlYTa adhesive layer on nickel base superalloy matrix (K417) by low temperature supersonic plasma spraying (LT-HVOF). Nano-7%Y_2O_3-ZrO_2 (7YSZ) ceramic coating was prepared by atmospheric plasma spraying (APS) on the bonding layer to obtain the structural evolution mechanism of the nano-ceramic layer under temperature gradient thermal cycle. Methods the working environment of temperature gradient thermal cycle of thermal barrier coating was simulated by gas thermal shock tester, and the interface temperature of each coating in thermal barrier coating was calculated by using one-dimensional steady-state heat conduction model. The diffusion growth mechanism of equal diameter grain and non equal diameter grain under thermal drive is discussed. Results when the number of thermal cycles was 40 times, the sintering densification appeared near the surface of the coating, while the coating at the bottom of the ceramic layer maintained the original structure. When the number of thermal cycles increases to 460, sintering densification occurs in the whole ceramic layer section. Conclusion temperature is the main factor of sintering densification of coating. When the curved neck is formed by equal grain contact, the diffusion rate of atoms in the grain is slow because the curved neck is only affected by the horizontal static pressure, which leads to the slow grain growth rate. When the bending neck is formed by non-equal grain contact, there is a shear force in the direction of large grain at the grain contact bending neck, which leads to the increase of grain diffusion rate to the bending neck and the faster grain growth rate.
【作者单位】： 广东省新材料研究所;现代材料表面工程技术国家工程实验室;华南理工大学材料科学与工程学院;
【基金】：国家“973”计划(2012CB625100)~~
【分类号】：TG174.453
本文编号：2489929
[Abstract]:Objective to prepare NiCoCrAlYTa adhesive layer on nickel base superalloy matrix (K417) by low temperature supersonic plasma spraying (LT-HVOF). Nano-7%Y_2O_3-ZrO_2 (7YSZ) ceramic coating was prepared by atmospheric plasma spraying (APS) on the bonding layer to obtain the structural evolution mechanism of the nano-ceramic layer under temperature gradient thermal cycle. Methods the working environment of temperature gradient thermal cycle of thermal barrier coating was simulated by gas thermal shock tester, and the interface temperature of each coating in thermal barrier coating was calculated by using one-dimensional steady-state heat conduction model. The diffusion growth mechanism of equal diameter grain and non equal diameter grain under thermal drive is discussed. Results when the number of thermal cycles was 40 times, the sintering densification appeared near the surface of the coating, while the coating at the bottom of the ceramic layer maintained the original structure. When the number of thermal cycles increases to 460, sintering densification occurs in the whole ceramic layer section. Conclusion temperature is the main factor of sintering densification of coating. When the curved neck is formed by equal grain contact, the diffusion rate of atoms in the grain is slow because the curved neck is only affected by the horizontal static pressure, which leads to the slow grain growth rate. When the bending neck is formed by non-equal grain contact, there is a shear force in the direction of large grain at the grain contact bending neck, which leads to the increase of grain diffusion rate to the bending neck and the faster grain growth rate.
【作者单位】： 广东省新材料研究所;现代材料表面工程技术国家工程实验室;华南理工大学材料科学与工程学院;
【基金】：国家“973”计划(2012CB625100)~~
【分类号】：TG174.453
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