| Summary: | 碩士 === 國立中興大學 === 材料科學與工程學系所 === 101 === In manufacturing industries, protective coatings have been applied onto the surfaces of tool parts to fulfill the demands of high hardness, thermal stability and abrasion resistance as well as to enhance the lifetime of the parts. In this study, multi-component (AlCrTaTiZr)NSix coatings were deposited by RF magnetron co-sputtering using AlCrTaTiZr-alloy and silicon targets, and their performances were characterized. It was found that, as the applied substrate bias and Si-target power increased, the (AlCrTaTiZr)NSix coatings transformed from a large columnar structure with a [111] preferred orientation to a dense and ultrafine nanocomposite structure. The coatings were strengthened, attributed to the densification of the coatings, the introduction of covalent-like bonds, the refinement of grains, the formation of nanocomposite structure and the existence of large lattice distortions. At an applied bias voltage of -100V and a silicon target power of 50W, the (AlCrTaTiZr)N0.82Si0.14 coating with a silicon content of 7.27% showed the best mechanical performance; the hardness, H/E ratio, and H3/E2 ratio of the coating increased from 13 to 30 GPa, from 0.06 to 0.117, and from 0.05 to 0.411 GPa, respectively, indicating a high resistance to plastic deformation and abrasion wear. From the lattice observations around nanoindent marks, the formation of large numbers of dislocations and lattice distortions was found, suggesting the deformation mechanism of the coating through the activities of low-angle dislocations and stacking faults. As the stress was released, the number of dislocations decreased and a perfect lattice structure was recovered.
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