被覆二氧化鈦之304不鏽鋼於含過氧化氫與溶氫之高溫純水環境的腐蝕行為研究

Corrosion Behavior of TiO2 Treated Type 304 Stainless Steels in High Temperature Pure Water Environments with Dissolved Hydrogen Peroxide and Hydrogen

李宗翰(Li, TsungHan)

指導教授 ： 葉宗洸 ； 王美雅

國立清華大學/原子科學院/工程與系統科學系/碩士(2014年)

摘要

二氧化鈦具n型半導體特性，照光下會產生自由電子，促使金屬基材表面帶有負電位，適合應用於具Cherenkov radiation的電廠爐心附近組件防蝕應用上。本研究主要探討在高溫高壓純水環境下，經二氧化鈦抑制性被覆處理的304不鏽鋼試片之電化學特性研究。304不鏽鋼試片首先在288°C及溶氧量300 ppb的水環境下進行為期14天的預長氧化膜處理，或於288°C且溶氧量300 ppb及溶氫量50 ppb之水環境下各浸放7天；接著再分別於150°C及280°C，含濃度10 ppm或100 ppm的二氧化鈦奈米粉末之純水環境下，以動態循環熱水沉積法進行為期4天的被覆處理；最後以電化學極化掃描(Electrochemical Potentiodynamic Polarization)分析經二氧化鈦處理及未處理的試片在288°C及過氧化氫濃度300 ppb或溶氫量50 ppb的水環境下之腐蝕行為；除此之外，同時亦會觀察在照射紫外光源後經二氧化鈦被覆的試片之光電效應。實驗結果顯示，在280°C進行被覆處理之試片的被覆量高於在150°C進行被覆處理之試片；此外，於過氧化氫濃度300 ppb或溶氫量50 ppb的水環境中，不論照光與否，經二氧化鈦被覆處理的試片之電化學腐蝕電位(Electrochemical Corrosion Cotential, ECP)都小於未處理的試片。

關鍵字

應力腐蝕龜裂 ； 二氧化鈦 ； 電化學腐蝕電位 ； 動態電位極化掃描

並列摘要

Titanium dioxide (TiO2) coupled with ultraviolet irradiation was selected as a coating material for corrosion mitigation of Type 304 stainless steel (SS) in high temperature water with different water chemistry conditions. Type 304 SS specimens were pre-oxidized in oxygenated pure water at 288°C for 14 days, or they were pre-oxidized in oxygenated pure water at 288°C for 7 days and then further exposed to hydrogenated pure water also at 288°C for another 7 days. The pre-oxidized specimens were deposited with TiO2 nanoparticles by hydrothermal deposition at 150°C or 280°C for 4 days in pure water with a TiO2 concentration of 10 ppm or 100 ppm. Electrochemical potentiodynamic polarization analyses were conducted to investigate the corrosion behavior of both TiO2-treated and pre-oxidized specimens in 288°C pure water with H2O2 concentration of 300 ppb or H2 concentration of 50 ppb. Ultraviolet (UV) irradiation was then imposed upon the TiO2-treated specimens to examine if there was any photoelectric effect on the corrosion behavior of the treated samples. The TiO2 loading on the specimen treated at 280°C was significantly greater than that treated at 150°C, as verified by the ICP-MS loading measurements. The results showed that UV irradiation on the TiO2 treated samples led to decreases in corrosion rate of the samples in high temperature water with the presence of hydrogen peroxide. Further examinations on the impact of UV irradiation on the corrosion behavior of TiO2 treated Type 304 SS samples in H2O2-rich or hydrogenated pure water are being conducted.

並列關鍵字

Stress corrosion cracking ； Titanium dioxide ； Electrochemical corrosion potential ； Electrochemical potentiodynamic polarization.

參考文獻

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