摘要
为了消除常规热障涂层的裂纹与热生长氧化物(TGO),研究了激光感应复合快速熔覆制备功能梯度氧化钇稳定的氧化锆(YSZ)和NiCrAlY涂层。结果表明,当激光扫描速度与送粉率分别提高到3200mm/min与90.63g/min时,激光感应复合快速熔覆获得的YSZ/NiCrAlY梯度涂层经检测无裂纹,具有良好的外形,且显微硬度呈梯度分布。原始粉末内立方氧化锆(c-ZrO2)、单斜氧化锆(m-ZrO2)、四方氧化锆(t-ZrO2)完全转变为亚稳态的四方氧化锆(t′-ZrO2)。梯度增加YSZ的涂层具有组织细小、致密、由柱状树枝晶组成的双相结构特征。此外,连续两层间界面消失,完全不同于单纯激光熔覆获得的陶瓷-粘结层双层结构的热障涂层。等温氧化后,激光感应复合快速熔覆功能梯度YSZ/NiCrAlY涂层内亚稳态的四方氧化锆(t′-ZrO2)转变为稳态的四方氧化锆(t-ZrO2),从而提高了高温合金GH4169的抗高温氧化性能。
To eliminate cracks and thermally grown oxide （TGO） in thermal barrier coatings （TBCs）, the functionally graded yttria-stabilized-zirconia （YSZ）/NiCrA1Y coating by laser induction hybrid rapid cladding （LIHRC） is investigated. The results show that the crack-free YSZ/NiCrAIY coating with good profile and gradual microhardness can be obtained when laser scanning speed and powder feeding rate increase to 3200 ram/rain and 90.63 g/min during LIHRC, respectively. The c-ZrO2, m-ZrO2 and t-ZrO2 phases in primary YSZ powder are all completely transformed into the metastable t＇-ZrO; phase. The fine, dense and dual-phase microstructure composed of columnar dendrites is characterized by the gradual increase of YSZ content in the coating. Moreover, the interface of consecutive layer disappears, which is different from ceramic layer-bond layer （i. e., double-layer） constituent of TBCs formed during the individual laser cladding. After the isothermal oxidation, the metastable t＇-ZrO2 phase in the LIHRC-formed functionally graded YSZ/NiCrAlY coating transforms into t-ZrO2, which can increase the oxidation resistance of superalloy GH4169.
出处
《中国激光》
EI
CAS
CSCD
北大核心
2013年第4期87-92,共6页
Chinese Journal of Lasers
基金
国家自然科学基金(51261027)资助课题
