| Summary: | 碩士 === 義守大學 === 材料科學與工程學系碩士班 === 95 === The study mainly investigates 8% yttria partially stabilized zirconia (Y-PSZ) by way of air plasma sprayed, which produced thermal barrier coating. To improve the properties of sprayed coatings, laser surface treatment was followed up air plasmas spraying in order to modify the TBCs, and then observed the surface mechanical properties. To estimate the possible improvement in the treated surfaces, relevant morphological and interaction characteristics compared with the untreated surfaces.
The experiential results show laser treatment produced smoother surfaces from rough untreated surfaces, due to densification and homogenization of the treated zone. Porosity distribution in the laser treated coatings also relatively reduced for untreated surfaces. Besides, treated surface containing cracks increased with laser power density and processing speed, because inevitably thermal stresses caused by the rapid solidification process. Microstructures change from lamellar to dendritic columnar and generate vertical cracks, as well as without cracks and pores at the interfacial regions. In addition, the phase transformation behavior of yttria partially stabilized zirconia TBCs was affected by the laser-treated process. The predominant constituent of the metastable T’-phase are susceptible to laser-treated, which the content decreased with laser-treated fluence and changed into equilibrium tetragonal phase.
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