용융 Al-Si 도금 강재의 고온 환경 노출 시 특성 향상에 미치는 금속 박막의 영향 = Effect of metal thin film on characteristic improvement of high temperature environment of hot-dip Al-Si coated steel

다국어 초록 (Multilingual Abstract)

In this study, the effect of Cr thin film deposition on the thermal stability and corrosion resistance of hot-dip Al-Si coated steel was investigated. Deposition of a high-quality Cr film with a thickness of about 300nm was attempted through thermal evaporation, and the deposited specimen was heat treated at 600˚C to induce the formation of an intermetallic compound between the Cr film and the Al-Si plating layer. Specimens were prepared before and after alloying heat treatment with the existing hot-dip Al-Si plated steel. In addition, for the test piece prepared in this way, it was heated for 24 hours in a heat treatment atmosphere of 500˚C that simulated a high-temperature environment, and material analysis such as surface and cross-sectional morphology, phase and crystal structure that changed after high temperature exposure was performed. As a result of phase analysis through grazing incidence X-ray diffraction, it was found that Cr alloy phases such as Al8Cr5 and Al13Cr2 were formed on the top of the plating layer of the specimen heat treated after depositing the Cr film. As a result of conducing a thermogravimetric test to analyze high-temperature oxidation resistance, it was confirmed that the formation of Fe-oxide was reduced as the exposure of Fe to the top surface was suppressed when exposed to a high-temperature environment due to the Cr film, and thus the high-temperature oxidation resistance was excellent. In addition, in order to analyze corrosion resistance electrochemical tests and salt spray tests were conducted on the test pieces before and after exposure to a high temperature environment. As a result of the heat treatment after the deposition of the Cr film, it was confirmed that the corrosion resistance was superior to that of the existing hot-dip Al-Si plated steel due to the stabilization of the oxide film layer due to the formation of Al8Cr5 and Al13Cr2 and the suppression of surface exposure of Fe due to the presence of the Cr film.

목차 (Table of Contents)

• 1. 이론적 배경 1
• 1.1. 용융 Al-Si 합금 도금 1
• 1.2. 고온 환경 노출에 따른 내식성 저하 2
• 1.3. 열 증착법 2
• 1.4. Cr 합금막의 내식 특성 2
• 2. 실험 방법 6
• 3. 실험 결과 및 고찰 9
• 3.1. 제작막의 미세구조 및 결정학적 특성 분석 9
• 3.2. 제작막의 표면 형상 분석 12
• 3.3. 제작막의 고온 내산화특성 평가 12
• 3.4. 고온 환경 노출에 따른 제작막의 내식특성 평가 13
• 3.5. 제작막의 특성 향상에 대한 고찰 15
• 4. 결론 39
• 5. 참고문헌 41