摘要
理论分析表明梯度结构能有效减缓氧化铝陶瓷层与基体结合面上的应力突变,涂层内部最大Mises应力明显降低,合理的梯度结构能改善涂层内部Mises应力分布,改变应力分布特征.为验证理论分析结果的正确性,采用等离子喷涂制备具有不同幂指数分布特征的6层“三明治”式梯度结构涂层,对梯度涂层结构进行表征,并试验研究涂层的结合强度及抗冲击性能.结果表明,试验用梯度结构具备=0.25,1.00,4.00次方幂指数梯度结构特征,不同结构梯度层结合强度均在14.0～18.0 MPa,幂指数p=1.00的涂层结合强度最好,而幂指数p=0.25涂层抗冲击性能最好,较线性结构梯度涂层提高了30％,较幂指数=4.00结构的梯度涂层提高了45％,冲击失效后涂层截面分析证实p=0.25次方幂指数梯度结构减少了表面陶瓷层的应力,减缓了陶瓷层基体间应力突变梯度,涂层失效是从底层开始的,失效形式为梯度涂层层状结构间出现分层,而p=1.00、4.00次方幂指数梯度结构涂层冲击失效表现为表面陶瓷层脱落.
Theory analysis results show gradient structure can reduce the stress mutation in the joint surface between the coating and the substrate comparing with the nongraded interface,the maximum Mises stress of the coatings is significantly reduced,reasonable graded structure can effectively improve the Mises stress distribution of the coatings and change the characteristics of stress distribution.Optimization of the microstructure is required to achieve reductions in certain critical stress components believed to be important for controlling interface failure,and an adopting gradient structure of 0.25 power exponent is proposed,which can effectively reduce impact loads and Mises stress mutations.Supersonic air plasma spraying is used to produce gradient coatings,coatings with designed exponential graded structure and 6 interlayers are prepared,the coatings specimen are analyzed and tested using for microstructure,bonding strength and impact resistance separately.The XRD analysis results of coatings cross-section show the gradient coating present multilayer structure with designed exponential grade characteristics,impact experimental results show impact resistance properties of coating with 0.25 power exponent graded structure increased by 30％ compared with linear gradient structure coating,and increased by 45％ compared with 4.00 power exponent graded structure coating.The impact stress of coating with structure of 0.25 power exponent graded reduced,the surfact of coating is not is destroged or peeled off,the graded mutilayer structure is layered,and the impact failure mode of gradient structure of 1.00 and 4.00 power exponent are surface layer peeled off.
出处
《机械工程学报》
EI
CAS
CSCD
北大核心
2014年第10期87-92,共6页
Journal of Mechanical Engineering
基金
广东省高等学校高层次人才资助项目(2011140184002)
关键词
梯度涂层
结合强度
冲击载荷
失效分析
gradient coating
bonding strength
impact load
failure analysis
