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標題: | 熱浸鍍鋅鋼板溶膠凝膠鈍化處理之研究 The Study of Sol-Gel Passivation Treatment on Hot-Dip Galvanized Steels |
作者: | Teck-Soon Chin 陳德順 |
指導教授: | 林招松(Chao-Sung Lin) |
關鍵字: | 熱浸鍍鋅鋼板,溶膠-凝聚鈍化處理,矽金屬醇鹽,前處理,硝酸鋁, Hot dip galvanised steel,sol-gel process,silane,pre-treatment,aluminium nitrate, |
出版年 : | 2017 |
學位: | 碩士 |
摘要: | 鋼鐵因著其適當的強度和低廉的價格而在我們的日常生活中扮演了重要的角色。腐蝕,材料劣化的行為是一種無可避免的與環境發生的化學或電化學反應進而成為了鋼鐵於工業及建築應用上其中一個至關重要的課題。鍍鋅是於鋼鐵上生成一擁有犧牲陽極效果的鋅層以增加其抗腐蝕能力,該鋅層會較鋼鐵率先腐蝕。在熱浸鍍鋅鈍化處理中具備障蔽保護能力及自我癒合能力的六價鉻鈍化處理,曾經是工業上的優先的抗腐蝕選擇。一直到六價鉻的高毒性被證實,並在2003歐盟通過危害性物質限制的指令下而被禁止使用。
溶膠-凝膠法是在室溫或接近室溫下,生成一和金屬物質及有機頂層皆有良好附著性的氧化薄層。溶膠-凝膠法是基於金屬醇鹽類的水解及縮合反應。利用3-gycidyloxypropyl trimethoxysilane (GPTMS) 及tetraethyl orthosilicate (TEOS)作為前驅物的複合型溶膠-凝膠鈍化處理,在鋁合金的腐蝕保護上效果較熱浸鍍鋅鋼板(GI)來得好是因為表面處有以氧化物或氫氧化物存在的鋁/鋅分佈不均勻所致。在近年的研究中,經過浸泡於硝酸鋁溶液進行前處理再以沉浸塗佈法溶膠-凝膠鈍化處理的方式能夠與熱浸鍍鋅鋼板表面上形成一較平整的表面,增進其抗腐蝕能力。實驗結果顯示,通過電子顯微鏡可觀察到此皮膜厚度約為80至200 nm,與傳統鉻酸鹽化成處理者互相匹配,電化學量測及鹽霧試驗則顯示了與未經前處理的熱浸鍍鋅鋼板溶膠-凝膠鈍化處理比較中,此皮膜能通過240 h的鹽霧測試,擁有更好的抗腐蝕能力。 Steel plays an important role in our daily life because of its high tensile strength and low cost. Corrosion is an inevitable chemical or electrochemical reaction of material with environment and it becomes one vital issues in the steel application in industry or construction. Galvanization can improve the ability to against the corrosion of the steel by applying a protective zinc coating that can be served as a sacrificial anode, coating corroding before the steel. Hexavalent chromium based passivation treatment of the steel with barrier and self-healing properties used to be a priority anticorrosion option in industry until the high toxicity of the hexavalent chromium was proved and related strict environmental regulation known as ROHS (Restriction of Hazardous Substances Directive) proposed as well in 2003 by the European Union. The sol-gel procedure is method to deposit a thin oxide film with a good adhesion to both metallic substrates and organic top coats at temperature near to room temperature. Sol –gel process is based on hydrolysis and condensation reaction of metal alkoxides. Formation of an organic inorganic hybrid coating with silane solution consist of 3-gycidyloxypropyl trimethoxysilane (GPTMS) and tetraethyl orthosilicate (TEOS) shows better result in corrosion protection of aluminium alloy than hot dip galvanised steel due to the uneven distribution of aluminium and zinc hydroxide/oxide on the surface. In this study, a pre-treatment with immersing the hot-dip galvanised steel (GI) in an aluminium nitrate sol before dipping into the silane sol seemed to be able to get a smooth HDG surface which was followed by an improvement of corrosion resistance properties. The experimental results show that a sol-gel coating with a comparable thickness about 80 – 200 nm to traditional chromate conversion coating had been observed via scanning electron microscopy (SEM). Besides, better anticorrosion properties than without pre-treatment one was obtained via electrochemical analysis and salt spray test last 240 h. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/60045 |
DOI: | 10.6342/NTU201700058 |
全文授權: | 有償授權 |
顯示於系所單位: | 材料科學與工程學系 |
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