铝合金挤压型材的钨-钛酸盐化学转化研究
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摘要
采用单因素实验法,以转化膜面密度、耐蚀性为主要评价指标,确定了6063铝合金钨-钛酸盐化学转化最佳工艺:H3PO410.0 mL/L,NaF 3.5 g/L,K2TiF61.1 g/L,Na2WO41.0 g/L,5-磺基水杨酸1.5 g/L,水基复配液,pH值为2.40,40℃,10 min。转化膜完整、均匀,呈灰白色,硫酸铜点滴法耐蚀时间为62 s。采用SEM和EDS分析了化学转化膜的表面形貌及成分,用动电位极化测试研究了转化膜的耐蚀性能。结果表明:钨-钛转化膜是由P、Ti、W、F、O、Al等元素组成的复合物;转化膜试样的自腐蚀电位Ecorr为-0.668 VSCE,较空白试样提高303 mV,说明转化膜呈阴极性;转化膜试样的自腐蚀电流密度Icorr为4.02×10-3μA/cm2,较空白试样降低3个数量级,耐蚀性有效增强。
Taking the surface density of chemical conversion coating and its corrosion protectiveness as the main evaluation indexes, the optimal process parameters of chemical conversion treatment with tungstate-and titanate-containing bath for 6063 Al-alloy extrusion were determined by single factor experiment: i.e. H3 PO410.0 m L/L, NaF 3.5 g/L, K2 Ti F61.1 g/L, Na2 WO41.0 g/L, 5-Sulfosalicylic acid 1.5 g/L,pH=2.40, solution temperature 40 ℃ and treatment time 10 min. The prepared conversion coating is intact, uniform and grayish white, of which the life-time before corrosion occurence by dropping test with copper sulfate solution is up to 62 s. The surface morphology and composition, as well as, corrosion performance of the coating were examined by SEM with EDS and dynamic polarization measurement. Results indicate that W-and Ti-containing conversion films are complex compounds composed of P, Ti, W, F,O and Al. The Ecorrof the conversion treated alloy is-0.688 V, which is 303 mV higher than that of the bare Al-alloy substrate, suggesting that the chemical conversion coating is cathodic. The Icorrof the conversion treated alloy is 4.02×10-3μA/cm2, which is three orders of magnitude lower than that of the contest alloy, manifesting the significant improvement of the corrosion resistance.
Taking the surface density of chemical conversion coating and its corrosion protectiveness as the main evaluation indexes, the optimal process parameters of chemical conversion treatment with tungstate-and titanate-containing bath for 6063 Al-alloy extrusion were determined by single factor experiment: i.e. H3 PO410.0 m L/L, NaF 3.5 g/L, K2 Ti F61.1 g/L, Na2 WO41.0 g/L, 5-Sulfosalicylic acid 1.5 g/L,pH=2.40, solution temperature 40 ℃ and treatment time 10 min. The prepared conversion coating is intact, uniform and grayish white, of which the life-time before corrosion occurence by dropping test with copper sulfate solution is up to 62 s. The surface morphology and composition, as well as, corrosion performance of the coating were examined by SEM with EDS and dynamic polarization measurement. Results indicate that W-and Ti-containing conversion films are complex compounds composed of P, Ti, W, F,O and Al. The Ecorrof the conversion treated alloy is-0.688 V, which is 303 mV higher than that of the bare Al-alloy substrate, suggesting that the chemical conversion coating is cathodic. The Icorrof the conversion treated alloy is 4.02×10-3μA/cm2, which is three orders of magnitude lower than that of the contest alloy, manifesting the significant improvement of the corrosion resistance.
引文
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[18] Huang X Z, Liu Q F, Zhang C, et al. Formation process of chromium-free Mn(VII)-Ti(IV)chemical conversion film on aluminum alloy[J]. Chin. J. Process. Eng., 2014, 14:860(黄啸竹,刘庆芬,张超等.铝合金锰(VII)-钛(IV)系无铬化学转化成膜工艺[J].过程工程学报, 2014, 14:860)
[2] Yang M J, Li K, Du Y, et al. Experimental characterization of ultrastructure of aviation aluminum alloys[J]. J. Aeronaut. Mater., 2017,37(1):36(杨明军,李凯,杜勇等.航空用铝合金超微结构实验表征[J].航空材料学报, 2017, 37(1):36)
[3] Xu L G, Ma D, Li S B, et al. Research progress of aluminum alloy chemical conversion technology[J]. Corros. Sci. Prot. Technol.,2016, 28:173(徐龙贵,马迪,李树白等.铝合金化学转化技术研究进展[J].腐蚀科学与防护技术, 2016, 28:173)
[4] Zuo X, Li W F, Mu S L, et al. Investigation of composition and structure for a novel Ti-Zr chemical conversion coating on 6063 aluminum alloy[J]. Prog. Org. Coat., 2015, 87:61
[5] Liu X H, Ouyang G, Zhan W. Investigation of chromium-free colored chemical conversion technology for 6063 aluminum alloy[J].Mater. Prot., 2014, 47(3):28(刘晓辉,欧阳贵,占稳. 6063铝合金无铬有色化学转化工艺探讨[J].材料保护, 2014, 47(3):28)
[6] Mohammadloo H E, Sarabi A A, Hosseini R M, et al. A comprehensive study of the green hexafluorozirconic acid-based conversion coating[J]. Prog. Org. Coat., 2014, 77:322
[7] Yi A H, Li W F, Du J, et al. Preparation and properties of chromefree colored Ti/Zr based conversion coating on aluminum alloy[J].Appl. Surf. Sci., 2012, 258:5960
[8] Qiao Y L, Dong Y, Zhou S L, et al. Performances of Ti-Zr conversion coating on aluminum alloy[J]. Mater. Prot., 2016, 49(12):54(乔永莲,董宇,周石磊等.铝合金表面钛锆转化膜的性能[J].材料保护, 2016, 49(12):54)
[9] Nordlien J H, Walmsley J C,?sterberg H, et al. Formation of a zirconium-titanium based conversion layer on AA6060 aluminium[J].Surf. Coat. Technol., 2002, 153:72
[10] Smit M A, Hunter J A, Sharman J D B, et al. Effect of organic additives on the performance of titanium-based conversion coatings[J]. Corros. Sci., 2003, 45:1903
[11] Wang E S, Yang B, Xu J B, et al. Technology and mechanism for zinc-system phosphating of aluminum[J]. Mater. Prot., 2010, 43(6):35(王恩生,杨波,徐俊波等.纯铝的锌系磷化工艺及机理[J].材料保护, 2010, 43(6):35)
[12] Li H L, Liu S Z. Modification research of fluorinetitanate conversion coating resistance on 6061 aluminum alloy[J]. Corros. Prot.,2015, 36:938(李红玲,刘双枝. 6061铝合金氟钛酸盐转化膜耐蚀性能的改性研究[J].腐蚀与防护, 2015, 36:938)
[13] Guo R G, Wang X C, Geng Z L, et al. Preparation of environmentally friendly conversion coating on aluminum alloy and its corrosion resistance[J]. Mater. Prot., 2008, 41(12):14(郭瑞光,王晓昌,耿志良等.环境友好型铝合金表面转化膜的制备及其耐蚀性能[J].材料保护, 2008, 41(12):14)
[14] Li Y, Lu Z. Progress in tungstate corrosion inhibition mechanism research[J]. Mater. Prot., 2000, 33(11):29(李燕,陆柱.钨酸盐缓蚀机理的研究进展[J].材料保护, 2000,33(11):29)
[15] Yu J M, Liu X H, Liang Y H. Research on feasibility of tungstate as seawater corrosion inhibitor[J]. Surf. Technol., 2006, 35(5):60(于静敏,柳鑫华,梁英华.钨酸盐作海水缓蚀剂可行性讨论[J].表面技术, 2006, 35(5):60)
[16] Fan S R. Syntheses and structural studies of 5-sulfosalicylate coordination compounds[D]. Hangzhou:Zhejiang University, 2008:23(范赛荣. 5-磺基水杨酸配合物的合成及结构研究[D].杭州:浙江大学, 2008:23)
[17] Chu Y Q, Zhang H L. The stability of the complexes of 3-phenylazo-5-sulfo-salicylic acid with transition metal(II), rare earth(III)and molybdenum(VI)[J]. J. Fudan Univ.(Nat. Sci.), 1999, 38(1):29(储艳秋,张华麟. 3-苯基偶氮-5-磺基水杨酸与过渡金属(II),稀土(III),钼(VI)的络合物稳定性[J].复旦学报(自然科学版),1999, 38(1):29
[18] Huang X Z, Liu Q F, Zhang C, et al. Formation process of chromium-free Mn(VII)-Ti(IV)chemical conversion film on aluminum alloy[J]. Chin. J. Process. Eng., 2014, 14:860(黄啸竹,刘庆芬,张超等.铝合金锰(VII)-钛(IV)系无铬化学转化成膜工艺[J].过程工程学报, 2014, 14:860)