聚合物前驱体陶瓷/YSZ热障涂层阻抗谱无损检测方法研究

Thermal barrier coatings and environmental barrier coatings have been widely employed to improve the lifetime and satiability of superalloy applied to high temperature and corrosion environment. The main problem for traditional thermal barrier coatings is that the thickening of thermal growth oxides on the bond-coat during high temperature oxidation trends to lead to the spallation and failure of coatings. Currently, the solution of this problem is to update the production method, such as electron beam physical vapour deposition, which consists of column grains and increases the strain tolerance of ceramic coatings. However, this method is complicated and expensive, which is used primarily in the most severe applications. In this study, the dip-coating method will be used to produce a polymer-derived ceramic coating between the traditional plasma-sprayed MCrAlY bond-coat and yttria-stabilized-zirconia top-coat. Then, the oxidized polymer-derived ceramic/yttria-stabilized-zirconia ceramic multi-layer thermal barrier coatings with different oxidation time will be characterized and analyzed by the nondestructive impedance evaluation. The oxidation kinetics of samples will also be investigated. By producing the SiNO/ZrO2 or SiCNO/TiSi2 polymer-derived ceramic coatings, the strain tolerance of ceramic coatings will be enhanced, and the diffusion of oxygen ions in ceramic coatings will be suppressed. Thus, the thickening of thermal growth oxides will be controlled and the lifetime of thermal barrier coatings will be prolonged. The impedance spectra of thermal barrier coatings will reflect the change in the thickness of oxides, the porosity, cracks, sintering and phase transformation of ceramic coatings. This is will help to obtain the oxidation mechanism and failure mechanism of this novel multi-coating. Present study will play an important role in exploring experimental and theoretical basis for low-cost surface modification of thermal barrier coatings.

热障涂层一直被广泛应用以改进合金在高温和腐蚀环境下的使用寿命及稳定性，但传统热障涂层的粘结层氧化后，热生长氧化物层会增厚而导致涂层剥落并失效。目前解决上述问题的主要方法是改进制备技术，如使用电子束物理气相沉积制备柱状晶结构陶瓷层提高其抗应变能力，从而提高涂层的使用寿命，但这类方法复杂并且昂贵。本项目针对上述问题，使用提拉法制备聚合物前驱体陶瓷层，在等离子喷涂制备的传统粘结层和陶瓷层间增加一个中间层。再通过阻抗谱无损检测技术对不同氧化时间的试样进行表征和分析。通过增加SiNO/ZrO2或SiCNO/TiSi2陶瓷中间层可以提高涂层的抗应变能力，并抑制氧离子在陶瓷层中的扩散，从而减缓氧化层的增厚，最终提高热障涂层的使用寿命。阻抗谱可以反映氧化层的厚度，陶瓷层中的孔隙，裂纹，烧结和相组成等变化，获知这种新型涂层的氧化机理和失效机理。研究将为探索热障涂层低成本有效表面改性途径提供实验和理论依据。

热障涂层一直被广泛应用以改进合金在高温和腐蚀环境下的使用寿命及稳定性，但传统热障涂层的粘结层氧化后，热生长氧化物层会增厚而导致涂层剥落并失效。目前解决上述问题的主要方法是改进制备技术，如使用电子束物理气相沉积制备柱状晶结构陶瓷层提高其抗应变能力，从而提高涂层的使用寿命，但这类方法复杂并且昂贵。本项目针对上述问题，使用提拉法制备聚合物前驱体陶瓷层，在等离子喷涂制备的传统粘结层和陶瓷层间增加一个中间层。再通过阻抗谱无损检测技术对不同氧化时间的试样进行表征和分析。通过增加SiNO陶瓷中间层可以提高涂层的抗应变能力，并抑制氧离子在陶瓷层中的扩散，从而减缓氧化层的增厚，最终提高了热障涂层的使用寿命。此外，还对多层结构的梯度热障涂层以及商用FeCrAlY合金的样品进行了氧化失效分析，从氧化层结构以及涂层受力等角度分析了涂层的失效机理。为了延长传统热障涂层的使用寿命，尝试了对涂层粘结层扩散预处理以及陶瓷层表面激光改性处理的方式，都制备出了超过普通热障涂层试样寿命的样品。研究将为探索热障涂层低成本有效表面改性途径提供实验和理论依据。