热震中7YSZ热障涂层结构演变

发布时间：2018-02-27 07:26

本文关键词： 热震热生长氧化物失效机理结构演变　出处：《无机材料学报》2015年12期 　论文类型：期刊论文

【摘要】：采用低温超音速等离子喷涂(LT-HVOF)在镍基高温合金基体上制备了Ni Co Cr Al YTa粘结层,使用大气等离子喷涂(APS)在粘结层上`制备了7wt%Y2O3-Zr O2(7YSZ)陶瓷层。基于动态试验即热震实验研究了粘结层的扩散氧化机制,探讨了陶瓷层的烧结及相变过程并观察了涂层的结构演变。实验结果表明:动态热循环下随着热震次数的增加,粘结层组元扩散氧化形成热生长氧化物(TGO)且厚度逐渐增加。此外,粘结层组元在温度梯度下沿陶瓷层内部裂纹向高温区扩散,最终在陶瓷层表面裂纹区域出现大量的金属氧化物,同时粘结层组元的扩散有助于陶瓷层的烧结,导致其显微硬度逐渐增大,而粘结层由于Kirkendall效应,其内部出现大量的孔洞导致其显微硬度逐渐降低。另外,陶瓷层在相变及热循环应力的作用下表面出现了大尺度的宏观裂纹。
[Abstract]:Ni Co Cr Al YTa bonding layer was prepared on the substrate of nickel base superalloy by low temperature hypersonic plasma spraying (LT-HVOF). A 7w t y _ 2O _ 3-Zr _ 2o _ 2o _ 2o _ 7YSZ ceramic coating was prepared on the adhesive layer by atmospheric plasma spraying (APS). The diffusion and oxidation mechanism of the adhesive layer was studied on the basis of dynamic test, that is, thermal shock test. The sintering and phase transition process of the ceramic layer were discussed and the structure evolution of the coating was observed. The experimental results show that the dynamic thermal cycle increases with the increase of the number of thermal shock. The bonding layer component is diffused and oxidized to form thermal growth oxide (TGOO) and its thickness increases gradually. In addition, the bonding layer component diffuses along the internal crack of ceramic layer to the high temperature region under the temperature gradient. Finally, a large number of metal oxides appear in the cracked area of the ceramic layer, and the diffusion of the bonding elements is helpful to the sintering of the ceramic layer, which leads to the increase of the microhardness of the ceramic layer, and the bonding layer is due to the Kirkendall effect. The microhardness of the ceramic layer decreases gradually due to a large number of pores. In addition, large scale macroscopic cracks appear on the surface of the ceramic layer under the action of phase transformation and thermal cycling stress.
【作者单位】：华南理工大学材料科学与工程学院;广州有色金属研究院现代材料表面工程技术国家工程实验室;广州有色金属研究院新材料研究所;
【基金】：国家“973”计划项目(2012CB625100) 国家“863”计划项目(2012AA03A512)~~
【分类号】：TG174.4

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