基于数字图像相关法的EB-PVD热障涂层体系拉伸失效分析
发布时间：2019-06-12 15:23
【摘要】：作为一种隔热防护的结构体系,在苛刻的服役环境下热障涂层能有效提高涡轮叶片的服役温度,降低了服役环境对于涡轮叶片金属基底的损伤。高温环境下热障涂层体系难以预测的界面失效及脱落问题极大限制了其广泛应用和可靠性评价。因此,目前亟待发展新型实验测试技术及实验设备完善热障涂层体系的高温力学性能,对于有效掌握其破坏机理具有重要的意义。本文改进了传统测试设备,发展了一种1600°C范围内材料力学性能测试的新方法,对传统的热障涂层体系进行了不同服役温度下的实验和裂纹失效机制分析。主要内容如下:第一,对传统的DIC测试设备进行升级改造。自主配置了两个高温放大镜头以及蓝光滤镜,引进了用于高温实验的补偿光源,充分解决了服役高温下实验的放大倍数不够、热辐射和光线不足等不稳定因素;发展了一种新型测试方法,可以实现1600°C范围内的材料力学性能测试,在位移场和应变场基准上验证了其可行性;并成功授权了一项高温散斑制备方法的发明专利(CN103792117A)。第二,基于上述改进的设备和方法,在常温和800°C~1000°C温度下对粘结层-基底结构进行拉伸实验,准确获得了整个拉伸实验中粘结层材料表面位移场和应变场的演化过程。通过对关键阶段和初始裂纹准确数据的提取,得到了随着温度升高临界断裂应变由0.35%逐渐地降低到0.21%;临界断裂强度由700 MPa降低到252 MPa;临界剪切强度由117.6 MPa降低到42.4 MPa,充分表明了实验温度对实验结果的影响;结合实验过程中数字图像相关法计算得到的全场应变云图和扫描电镜微观形貌图,详细探讨了不同服役温度下粘结层-基底结构失效机制。第三,利用搭建的测试平台在常温和800°C~1000°C服役温度下进行拉伸实验,计算分析得到EB-PVD热障涂层体系表面位移场和应变场的演化过程。提取出关键阶段和初始裂纹相关数据并结合拉曼光谱法测试得到的陶瓷层表面残余应力值,得到EB-PVD热障涂层体系陶瓷层临界断裂应变逐渐由0.45%降低到0.12%;相对应的临界断裂强度由239.7 MPa降低到74 MPa;临界剪切强度由53.8 MPa降低到20.5 MPa,充分表明了实验温度对实验结果的影响;相似地,借助实验后试样的宏微观形貌图和数字图像相关法计算得到的全场应变云图,详细探讨了不同服役温度下三层结构EB-PVD热障涂层体系失效机制。
[Abstract]:As a kind of thermal insulation protection structure system, the thermal barrier coating can effectively increase the service temperature of turbine blades and reduce the damage to the metal substrate of turbine blades in harsh service environment. The interface failure and shedding of thermal barrier coating system which is difficult to predict in high temperature environment greatly limit its wide application and reliability evaluation. Therefore, it is urgent to develop new experimental testing technology and experimental equipment to improve the high temperature mechanical properties of thermal barrier coating system, which is of great significance for effectively mastering its failure mechanism. In this paper, the traditional testing equipment is improved, and a new method for testing the mechanical properties of materials in the range of 1600 掳C is developed. the experiments and crack failure mechanism analysis of the traditional thermal barrier coating system at different service temperatures are carried out. The main contents are as follows: first, upgrade the traditional DIC test equipment. Two high temperature magnifying lenses and blue light filters are equipped independently, and the compensation light source for high temperature experiment is introduced, which fully solves the unstable factors such as insufficient magnification, thermal radiation and insufficient light in the service high temperature experiment, and a new testing method is developed, which can realize the mechanical properties test in the range of 1600 掳C, and its feasibility is verified on the in-situ shift field and strain field benchmark. A patent for the preparation of high temperature speckle (CN103792117A) has been successfully authorized. Secondly, based on the above improved equipment and method, the tensile experiments of bonding layer-substrate structure at room temperature and 800 掳C ~ 1000 掳C were carried out, and the evolution process of surface displacement field and strain field of bonding layer material in the whole tensile test was obtained accurately. Through the extraction of the accurate data of the key stage and the initial crack, it is obtained that the critical fracture strain decreases from 0.35% to 0.21% with the increase of temperature, and the critical fracture strength decreases from 117.6 MPa to 252 MPa; critical shear strength from 117.6 MPa to 42.4 MPa, which fully indicates the effect of the experimental temperature on the experimental results. Combined with the whole field strain cloud diagram and scanning electron microscope microtopography calculated by digital image correlation method, the failure mechanism of bonding layer-substrate structure at different service temperatures is discussed in detail. Thirdly, the tensile experiments were carried out at room temperature and 800 掳C ~ 1000 掳C, and the evolution process of surface displacement field and strain field of EB-PVD thermal barrier coating system was calculated and analyzed. The residual stress on the surface of ceramic layer measured by Raman spectroscopy was obtained by extracting the relevant data of critical stage and initial crack, and the critical fracture strain of ceramic layer in EB-PVD thermal barrier coating system gradually decreased from 0.45% to 0.12%, and the corresponding critical fracture strength decreased from 239.7 MPa to 74 MPa;. The decrease of critical shear strength from 53.8 MPa to 20.5 MPa, fully shows the effect of experimental temperature on the experimental results. Similarly, the failure mechanism of three-layer EB-PVD thermal barrier coating system at different service temperatures is discussed in detail with the help of the macro and micro morphology of the sample and the full field strain cloud diagram calculated by digital image correlation method.
【学位授予单位】：湘潭大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TG174.4
[Abstract]:As a kind of thermal insulation protection structure system, the thermal barrier coating can effectively increase the service temperature of turbine blades and reduce the damage to the metal substrate of turbine blades in harsh service environment. The interface failure and shedding of thermal barrier coating system which is difficult to predict in high temperature environment greatly limit its wide application and reliability evaluation. Therefore, it is urgent to develop new experimental testing technology and experimental equipment to improve the high temperature mechanical properties of thermal barrier coating system, which is of great significance for effectively mastering its failure mechanism. In this paper, the traditional testing equipment is improved, and a new method for testing the mechanical properties of materials in the range of 1600 掳C is developed. the experiments and crack failure mechanism analysis of the traditional thermal barrier coating system at different service temperatures are carried out. The main contents are as follows: first, upgrade the traditional DIC test equipment. Two high temperature magnifying lenses and blue light filters are equipped independently, and the compensation light source for high temperature experiment is introduced, which fully solves the unstable factors such as insufficient magnification, thermal radiation and insufficient light in the service high temperature experiment, and a new testing method is developed, which can realize the mechanical properties test in the range of 1600 掳C, and its feasibility is verified on the in-situ shift field and strain field benchmark. A patent for the preparation of high temperature speckle (CN103792117A) has been successfully authorized. Secondly, based on the above improved equipment and method, the tensile experiments of bonding layer-substrate structure at room temperature and 800 掳C ~ 1000 掳C were carried out, and the evolution process of surface displacement field and strain field of bonding layer material in the whole tensile test was obtained accurately. Through the extraction of the accurate data of the key stage and the initial crack, it is obtained that the critical fracture strain decreases from 0.35% to 0.21% with the increase of temperature, and the critical fracture strength decreases from 117.6 MPa to 252 MPa; critical shear strength from 117.6 MPa to 42.4 MPa, which fully indicates the effect of the experimental temperature on the experimental results. Combined with the whole field strain cloud diagram and scanning electron microscope microtopography calculated by digital image correlation method, the failure mechanism of bonding layer-substrate structure at different service temperatures is discussed in detail. Thirdly, the tensile experiments were carried out at room temperature and 800 掳C ~ 1000 掳C, and the evolution process of surface displacement field and strain field of EB-PVD thermal barrier coating system was calculated and analyzed. The residual stress on the surface of ceramic layer measured by Raman spectroscopy was obtained by extracting the relevant data of critical stage and initial crack, and the critical fracture strain of ceramic layer in EB-PVD thermal barrier coating system gradually decreased from 0.45% to 0.12%, and the corresponding critical fracture strength decreased from 239.7 MPa to 74 MPa;. The decrease of critical shear strength from 53.8 MPa to 20.5 MPa, fully shows the effect of experimental temperature on the experimental results. Similarly, the failure mechanism of three-layer EB-PVD thermal barrier coating system at different service temperatures is discussed in detail with the help of the macro and micro morphology of the sample and the full field strain cloud diagram calculated by digital image correlation method.
【学位授予单位】：湘潭大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TG174.4
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1 王利强 ,阎殿然 ,何继宁 ,宋向阳;热障涂层研究状况及进展[J];新技术新工艺;2002年03期
2 谢冬柏,王福会;热障涂层研究的历史与现状[J];材料导报;2002年03期
3 刘志;周洪;;热障涂层研究进展[J];河海大学常州分校学报;2006年03期
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