相对法评价陶瓷涂层残余应力与界面结合强度

发布时间：2018-11-17 11:55

【摘要】：随着科学技术的发展,工程设备及构件的工作条件日益苛刻,传统材料难以满足工程需求。陶瓷涂层因具有耐高温、耐腐蚀、耐氧化、高强度等优越性能得到越来越广泛地应用。对于陶瓷涂层而言,涂层残余应力与界面结合强度是决定其工程使用安全可靠性的重要性能指标,但它们却常常难以准确评价。针对陶瓷涂层残余应力难以测试的现状,本研究采用相对法理论,分别建立了对同温涂层与异温涂层的残余应力评价方法,其中,同温涂层为制备时涂层与基体材料处于相同温度的涂层,如CVD涂层;异温涂层为制备时涂层与基体材料处于不同温度的涂层,如热喷涂涂层。另一方面,对于陶瓷涂层界面结合强度评价,本研究提出改进十字交叉法测试界面结合强度,并结合相对法对界面破坏形式进行了分析。1.针对陶瓷同温涂层残余应力评价难题,基于均匀应变模型和相对法理论,根据材料的几何相容性与受力平衡原理,建立了同温涂层残余应力评价方程,通过测量涂层与基体的弹性模量、热膨胀系数、横截面积与等效温度即可算出同温涂层残余应力。2.对于陶瓷异温涂层,当样品为单面涂层并产生弯曲变形时,可采用经典的Stoney公式测试曲率计算残余应力,定义这类样品为Stoney型涂层,否则为非Stoney型涂层。工程中大量的涂层构件不发生弯曲变形,均属于非Stoney型涂层,这类涂层残余应力评价是陶瓷涂层领域的关键。本研究采用相对法理论建立Stoney型涂层和非Stoney型涂层的残余应力之间的解析关系,Stoney型涂层的残余应力可通过Stoney公式测试,从而使得非Stoney型涂层的残余应力可通过其关系式计算出来。3.针对陶瓷涂层界面结合强度评价,采用十字交叉法并改进样品制备要求,确保在十字交叉法剪切测试时,界面受到的是纯剪切力,避免弯矩的产生,同时使得界面剪切强度测试不再受到粘结剂强度的限制;通过对十字交叉夹具的修正,避免了在涂层拉伸强度测试过程中摩擦力的产生,提高了测量结果的准确性。
[Abstract]:With the development of science and technology, the working conditions of engineering equipment and components are increasingly harsh. Ceramic coatings are more and more widely used because of their excellent properties such as high temperature resistance, corrosion resistance, oxidation resistance and high strength. For ceramic coatings, the residual stress and interface bonding strength are important performance indexes to determine the safety and reliability of the coatings, but they are often difficult to evaluate accurately. In view of the present situation that the residual stress of ceramic coating is difficult to be measured, the method of evaluating residual stress of the same temperature coating and the different temperature coating is established by using the theory of relative method. The same temperature coating is the coating at the same temperature as the substrate material, such as CVD coating. Heterothermic coating is a kind of coating, such as thermal spraying coating, when the coating and substrate material are at different temperatures. On the other hand, for the evaluation of the interface bonding strength of ceramic coatings, an improved cross method is proposed to test the interface bond strength, and the failure mode of the interface is analyzed in combination with the relative method. 1. Based on the uniform strain model and the theory of relative method, the residual stress evaluation equation of the same temperature coating is established according to the principle of geometric compatibility and stress balance of the ceramic coating at the same temperature. By measuring the elastic modulus, coefficient of thermal expansion, cross-sectional area and equivalent temperature of the coating and substrate, the residual stress of the coating at the same temperature can be calculated. When the sample is a single-sided coating and bending deformation occurs, the residual stress can be calculated by using the classical Stoney formula to measure the curvature of the coatings. The samples are defined as Stoney coatings, otherwise they are non-Stoney coatings. A large number of coating components do not bend and deform in engineering, all of them belong to non-Stoney coating. The residual stress evaluation of this kind of coating is the key in the field of ceramic coating. In this study, the analytical relationship between residual stress of Stoney coating and non-Stoney coating is established by using the relative method theory. The residual stress of Stoney coating can be measured by Stoney formula. Thus, the residual stress of non Stoney coating can be calculated by its relationship. According to the evaluation of the bonding strength of ceramic coating interface, the cross method is adopted and the sample preparation requirements are improved to ensure that the interface is subjected to pure shear force during the cross shear test, so as to avoid the generation of bending moment. At the same time, the interfacial shear strength testing is no longer limited by the bond strength. By modifying the cross clamp, the friction force is avoided during the tensile strength test of the coating, and the accuracy of the measurement results is improved.
【学位授予单位】：中国建筑材料科学研究总院
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG174.453

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