Development of Evaluation Methods for Thermal Stress Relief Type Ceramic Coating Design

本研究的目的是发展的方法来评估热应力释放型陶瓷涂层的基础上瞬态热应力分析。本研究特别关注功能梯度材料（FGMs）的发展。在本研究中，开发了以下评价和分析方法来评价功能梯度材料的抗热震性。(1)成分材料的机械性能评价（小冲杆试验法）为了确定FGM在热环境下的最佳微观结构，在材料设计中需要作为成分混合比的函数的机械性能。为此，开发了小冲杆（SP）方法，用于使用薄的小型化试样（0.5*10* 10 mm）测定弹性模量和断裂性能。用SP法建立了SiC/C和ZrO_2/金属复合材料性能数据库。(2)用有限元法计算瞬态热应力的计算机模拟方法对SiC/C和ZrO_2/金属涂层等几种功能梯度材料在应用热环境下的瞬态热应力进行了分析。还进行了分析，以模拟激光加热的测试，以促进制造-评估循环。利用模拟方法，研究了梯度组织变化对瞬态热应力的影响。(3)抗热震性评价方法（激光和等离子弧加热技术）激光和等离子弧加热方法辅以瞬态热应力分析，开发了用于评价功能梯度材料抗热震性的方法。测试证明了功能梯度材料的有用性，以减轻陶瓷涂层材料内的诱导热应力。

The objective of this research is to develop methods for evaluating thermal stress relief type ceramic coatings on the basis of transient thermal stress analyses. This study especially focuses on the development of functionally gradient materials ( FGMs ). The following evaluation and analysis methods were developed for evaluating the thermal shock resistance of FGMs in this study.(1) Evaluation of mechanical properties of constituent materials ( Small punch testing method )In order to determine the optimum microstructure of FGMs under the thermal environment, the mechanical properties as a function of the mixture ratio of the component are required for the materials design. For this purpose, the small punch ( SP ) method was developed for determining the elasticity modulus and fracture properties using a thin, miniaturized specimen ( 0.5*10*10mm ). By use of the SP method a material properties data base was established for SiC/C and ZrO_2/metal composiltes.(2) Computer simulation method for evaluating transient thermal stress using a finite element methodTransient thermal stress analyses were conducted on several FGMs such as SiC/C and ZrO_2/metal coating systems under the thermal environments of their applications. The analyses were also performed to simulate the test of laser heating in order to facilitate the fabrication- evaluation loop. Using the simulation method, the effect of varying the gradient microstructure on the transient thermal stresses was examined.(3) Thermal shock resistance evaluation method ( Laser and plasma-arc heating technique )Laser and plasma-arc heating methods supplemented by the transient thermal stress analysis were developed to evaluate the thermal shock resistance of FGMs. The tests demonstrated the usefulness of FGMs to mitigate the induced thermal stress within the ceramic coating materials.