壓鑄鎂合金植酸轉化處理中添加劑的研究

壓鑄鎂合金植酸轉化處理中添加劑的研究/宋東福等壓鑄鎂合金植酸轉化處理中添加劑的研究*宋東福' ,趙雅情',戚文軍',梁濤’,農登l(1 廣州有色金屬研究院材料加工研究所,廣州510650; 2廣州市機械科學(xué)研究院有限公司,廣州510700)摘要通過(guò)在植酸基礎轉化液中添加兩種不同組成的成膜促進(jìn)劑制備鎂合金植酸轉化膜，采用SEM、EDS及失重法研究了添加劑對轉化膜結構、形貌及耐蝕性能的影響。結果表明:經(jīng)植酸轉化處理后,鎂合金表面耐蝕性能均得到了大幅提高，120 h鹽水浸泡后失重率僅為鎂合金基材的1/5;Ca(NO3)z、NH,VO3及NaC.HO%●2H2O組合添加劑的加入有利于改善膜層結構和致密性,轉化膜由完整、致密且與基材結合緊密的內層和網(wǎng)紋的外層組成,耐蝕性能較純植酸轉化膜提高1倍,而NaF、Nar: BO及NaeCH4O%●2H2O的組合添加劑則對轉化膜結構和耐蝕性能影響不顯著(zhù)。關(guān)鍵詞鎂合金添加劑植酸轉化膜 失重率中圖分類(lèi)號:TG178文獻標識碼:AStudy on Additives in Phytic Acid Treatment for Diecasting Magnesium AlloySONG Dongfu'，ZHAO Yaqing'，QI Wenjun'，LIANG Tao2，NONG Deng'(1 Material Processing Institute ,Guangzhou Research Institute of Non- ferrous Metals,Guangzhou 510650;2 Guangzhou Mechanical Engineering Research Institute CO. ,LTD, Guangzhou 510700)AbstractTwo different kinds of phytic acid conversion coatings on magnesium alloy were prepared in phyticacid base conversion solution with accelerants. The effect of additives on the structure, morphology and corrosion re-sistance of conversion coating were investigated by SEM, EDS and weight loss method, respectively. The results showthat the magnesium alloy surface corrosion performance is improved substantially through phytic acid conversion treat-ment, and the weight loss of conversion coating is only 1/5 of the magnesium alloy substrate after 120 h saline soa-king. The structure and compactness of conversion coating are greatly improved by adding Ca(NOz)z ,NH VO3 andNa2C. H,O%●2H2O, as the conversion coating consists of inner layer which is combined with the substrate compactlyand outer layer which exhibits overlapping curve. The corrosion resistance of corversion coating increases 100% com-pared to pure phytic acid conversion coating. However, other additives such as NaF,Naz BO and Na2CH4O%●2H2Ohave no significant impact on structure and corrosion resistance of phytic acid conversion coating.Key words magnesium alloy, additive, phytic acid conversion coating, weight-loss ratio鎂及鎂合金具有比強度和比剛度高、鑄造性能好、電磁等6種有毒有害物質(zhì)的RoHS指令。擁有百年歷史的金屬屏蔽和阻尼性能良好及可回收利用等優(yōu)點(diǎn),廣泛應用于航空表面鉻酸鹽處理傳統工藝受到限制,開(kāi)發(fā)其替代工藝迫在眉航天、汽車(chē)摩托車(chē)、電動(dòng)工具、電子通訊、光學(xué)儀器、計算機等睫,在這樣的形勢下,鎂合金低成本、環(huán)境友好型無(wú)鉻轉化工領(lǐng)域”。但耐蝕性差成為了制約鎂合金應用于苛刻領(lǐng)域的藝,如高錳酸鹽、鉬酸鹽.錫酸鹽、鈷酸鹽、有機轉化膜、稀土三大技術(shù)瓶頸之- _[C。 為了改善鎂合金表面的耐蝕性能,許等體系8-1]成為各國研究的熱點(diǎn)。多防護處理方法相繼被開(kāi)發(fā)出來(lái),如化學(xué)轉化、陽(yáng)極氧化、微植酸是廢棄谷殼的提取物,其分子中含有6個(gè)磷酸基，弧氧化、金屬覆層、氣相沉積以及有機涂層等13-1 ,其中化學(xué)是一種少見(jiàn)的金屬多齒螯合劑。當其與金屬絡(luò )合時(shí),易形成轉化法因具有工藝簡(jiǎn)單、成本低廉、不受工件形狀和尺寸的多個(gè)整合環(huán),且所形成的絡(luò )合物穩定性極強。同時(shí),植酸膜影響以及與有機涂層結合力強等優(yōu)點(diǎn)0:1]而備受青睞。最早表面富含羥基和磷酸基等有機官能團,對提高鎂合金表面涂應用于工業(yè)化生產(chǎn)的轉化膜是鉻酸鹽系列，以美國的DOW裝的附著(zhù)力進(jìn)而提高其耐蝕性具有非常重要的意義。崔秀公司開(kāi)發(fā)的一系列處理液為代表,該法工藝成熟，所得轉化芳等[1]采用純植酸溶液制備的鎂合金植酸轉化膜覆蓋度高，膜性能優(yōu)良,在第二次世界大戰期間得到了大規模的應用，無(wú)開(kāi)裂現象,成膜后自腐蝕電流密度降低6個(gè)數量級,大幅但處理液中含有毒的Cr離子,對人體和環(huán)境危害極大,歐盟提高了AZ91D鎂合金的耐蝕性。鄭潤芬等[4 -16]也通過(guò)實(shí)驗已于2003年通過(guò)了關(guān)于在電氣電子設備中限制使用六價(jià)鉻得到了類(lèi)似的中國煤化工中于純植酸溶液條YHCNMH G*廣東省粵港關(guān)鍵領(lǐng)域重點(diǎn)突破項目(2010A090604001);廣東省重大科技專(zhuān)項(zv1IAvOU4UUU5;宋東福:男,1984年生,碩士,工程師,主要從事輕合金加工與成型技術(shù)研究Tel:020-37238039 E-mail:375462908@qq. com.●102●材料導報B:研究篇2013年10月(下)第27卷第10期(2)Ca(NO2)2、NH,VO3及Na2CHO?！?H2O組合添magnesium based metal matrix composites []. 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