【摘要】：鎂是繼鋼鐵、鋁之后的第三大金屬工程材料,被譽為“21世紀綠色工程材料”,具有許多優(yōu)良的性能,通常以鎂合金型材的形式使用,應(yīng)用前景極為廣泛。鎂合金型材主要應(yīng)用在化學(xué)化工、電子工業(yè)、交通工具、航空航天工業(yè)等行業(yè)。目前鎂合金型材防腐所使用的技術(shù)比較落后,主要有鉻酸處理及非鉻酸處理兩種方法。鉻酸處理因其處理時間短、溫度高、濃度高而具有操作難度大、成本高、污染嚴重等缺點。非鉻酸處理技術(shù)不成熟。本課題在實際試用過程中,已經(jīng)克服了以上缺點,找到了一個經(jīng)濟、環(huán)保操作條件溫和,對材料適應(yīng)性廣,通用性強的處理辦法。本課題通過試驗研究了鎂合金(AZ91)的化學(xué)氧化和電化學(xué)氧化兩種成膜機理及其質(zhì)量影響因素。其中,用Cr O3(5g/L)、Ca SO4(5g/L),室溫處理2min,得到鎂合金化學(xué)氧化膜,對其電化學(xué)腐蝕性能進行表征,結(jié)果表明:該膜的自腐蝕電位為-1.358V;用200g/LCr O3、20g/L Ca SO4、30g/LNa NO3處理2min,自腐蝕電位為-1.461V。低濃度鉻酸氧化也可達到高濃度氧化的抗腐蝕效果,產(chǎn)品滿足GB6807-2001和GB6807-86標準,被氧化的鎂合金經(jīng)靜電噴涂75μm環(huán)氧/聚酯粉末涂料,其附著力、鹽霧試驗均滿足正常使用�？紫堵式�(jīng)檢測達到5%左右。鉻酸鹽氧化鎂合金做涂裝前處理,具有經(jīng)濟適用和自修復(fù)的特點,廢水經(jīng)處理后可達到排放標準。近年來,水污染形勢嚴峻,一些地方嚴格禁止使用污染嚴重的六價鉻,為此本課題進行了非鉻的電化學(xué)氧化研究。預(yù)處理的鎂合金,在80~85℃下,電化學(xué)氧化液組成為280 g/L的Na OH、36 g/L的Na2Si O3、4 g/L的苯酚氧化9~10min,所得膜。表面光潔完整,自腐蝕電位為-1.440V,孔隙率≤70%,封閉后可以滿足涂裝前處理要求。涂裝后根據(jù)國標GB/T 9286-88規(guī)定,采用劃格法測試,附著力為“0-1”級。根據(jù)國標GB/T 1771-1991進行漆膜耐鹽霧試驗,測試結(jié)果:35℃下120小時無腐蝕現(xiàn)象產(chǎn)生。漆膜耐濕熱性測定,根據(jù)GB/T1740-1979測定,96小時后漆膜無氣泡、開裂等現(xiàn)象。研究結(jié)果表明:本課題確定的鎂合金成膜方法可以實現(xiàn)處理液低濃度和低溫度,通過延遲處理時間和降低腐蝕速度來提高漆膜穩(wěn)定性并降低成本的目的。方法為大型鎂合金型材的涂裝前處理工程化奠定了基礎(chǔ)。
[Abstract]:Magnesium is the third largest metal engineering material after steel and aluminum. It is known as "green engineering material in the 21st century", and has many excellent properties. It is usually used in the form of magnesium alloy profiles, and its application prospect is very wide. Magnesium alloy profiles are mainly used in chemical and chemical industry, electronic industry, transportation tools, aerospace industry and other industries. At present, the anti-corrosion technology of magnesium alloy profiles is backward, mainly chromic acid treatment and non-chromic acid treatment. Chromic acid treatment is difficult to operate, high cost and serious pollution due to its short treatment time, high temperature and high concentration. Non-chromic acid treatment technology is not mature. In the process of practical trial, this subject has overcome the above shortcomings, and found an economic, environmental protection, mild operating conditions, wide adaptability to materials, strong versatility. In this paper, the mechanism of chemical oxidation and electrochemical oxidation of magnesium alloy (AZ91) and the influencing factors of its quality were studied. Cr O 3 (5g/L), Ca SO4 (5g/L) was used to prepare the chemical oxidation film of magnesium alloy at room temperature for 2 min. The electrochemical corrosion properties of the film were characterized. The results showed that the corrosion potential of the film was-1.358V, and the corrosion potential of the film was-1.358V. When treated with 200g/LCr O3, 20g / L Ca SO4,30g/LNa NO3 for 2 min, the self corrosion potential was-1.461V. Low concentration chromic acid oxidation can also achieve the high concentration oxidation anti-corrosion effect, the product meets the GB6807-2001 and GB6807-86 standard, the oxidized magnesium alloy by electrostatic spraying 75 渭 m epoxy / polyester powder coating, its adhesion, salt spray test meet the normal use. The porosity was about 5%. The pretreatment of chromate magnesium oxide alloy has the characteristics of economical application and self-repair, and the waste water can meet the discharge standard after treatment. In recent years, the situation of water pollution is serious, and the use of heavily polluted hexavalent chromium is strictly prohibited in some places. Therefore, the electrochemical oxidation of non-chromium has been studied in this paper. The pre-treated magnesium alloy was prepared by electrochemical oxidation of 280g / L Na OH,36 / g / L Na2Si-O3 and 4g / L phenol for 9min at 80 ~ 85 鈩，

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