In recent year, many structures and devices are exposed in severe environments, such as high temperature, high pressure, complex atmosphere etc. Therefore, thermal spray coatings play a role in protection of substrate materials under such severe environments. However, in the case of exposing such environments, there is a possibility that unpredictable degradation or damage occurs. Accordingly, elucidation of the mechanism of degradation and damage of the coatings is very important. Moreover, the diagnostic of degradation and damage for the structure based on the mechanism improves the reliability and safety of the structure with coatings. In this article, reliability and safety study for thermal spray coatings, which is exposed in severe environments, is described. In particular, degradation mechanisms of the coatings and their nondestructive evaluation technique are mentioned.
The material thermal processing using the nano-technology is now advanced towards more precise and controllable smart stage. Regarding plasma processing, plasma system with high precise, has been expected for smart thermal processing. A gas tunnel type plasma system exhibits high energy density and also high efficiency. One practical application of plasma processing is thermal spraying of ceramics such as Al2O3 and ZrO2. The characteristics of these ceramic coatings were superior to the conventional ones. The ZrO2 composite coating has the possibility of the development of high functionally graded TBC (thermal barrier coating). In this paper, the performance such as the mechanical properties, thermal behavior and high temperature oxidation resistance of the alumina/zirconia functionally graded TBCs produced by gas tunnel type plasma spraying was described and discussed. The results showed that the alumina/zirconia composite system exhibited the improvement of mechanical properties and oxidation resistance. Now, one of the advanced plasma application is expected to obtain the desired characteristics of ceramics with improved corrosion resistance, thermal resistance, and wear resistance. One application of the smart coating technology is a formation of Hydroxiapatite coating for bio-medical application, and another is the metallic glass coating with high function.
In state-of-the art semiconductor equipment such as dry etchers, CVD and PVD chambers as well as in the liquid crystal manufacturing industry, it is very important to consistently keep silicon wafers or glass on the susceptor. The main objectives are to improve the accuracy of both positioning and temperature control. Generally electrostatic adsorption force is used for holding silicon wafers or glass inside of a treatment chamber. The sintered ceramics, the polymer resin, and the thermal sprayed ceramic coatings are used as the dielectric substance to isolate and protect the surface of the electrostatic chuck and limit contamination and particle generation. However, investigations of the electrostatic adsorption force through thermal sprayed ceramic coatings have been limited. In this study, a ceramic coating having the electrostatic adsorption force was developed and its basic mechanical and electrical characteristics were investigated, and compared with those of sintered ceramics.