Colourful Phosphating Technics And Film-Forming Mechanism Research Of Steel

In metal superficial treatment fileds, phosphating technology is a kind of technics which is used wildly and more mature.Developing non-poisonous and low pollution normal temperature phosphate solution is the focus of study of people at present, but,in normal temperature phosphate solution which existed now,most of phosphate film made by zinic series phosphate solution are coloured by black and gray, they have good corrosion resistance but lack of good decorative effect,and for iron series phosphate solution, multi-coloured phosphate film which has good decorative effect can be obtained,but the techincs is not stable,and the corrosion resistance of the film is not so good.so the phosphate film which have both good corrosion resistance and decorative appearance is needed bo be studied.Under these backgrounds, in foundation of analysising low and normal temperature of phosphating technologies situations both at home and abroad,golden-brown phosphate film and blue phosphate film was developed in two kind of normal temperature phosphate solution with non-poisinous and non-sludge through single factor experiment investigation and orthogonal experiment optimization.The colusion and leading are as follows:1.According to singal factor experiment investigation,make sured the formulation and leading ingredient content range of new normal temperature,non-poisinous,non-sludage,golden-brown phophating phosphate solution.2.Based on basic phosphate solution prescription,being sured the most optimization prescription of golden-brown phosphating phosphate solution and its technological parameters range. The formulation and technological parameters of the phopate solution are as follows:HO-R-COOH 3.0g/L; accelerator 3.5g/L; Na3PO43.0 g/L; Zn2+4.8g/L; Mn(H2PO4)2·2H2O 1.2g/L; H3PO413.6 mL/LRange of phopahting temperature:25～31℃;Range of pH value of phosphate solution:2.34～2.84; the time of phosphating:15-20min.Good appearance and corrosion resistance golden-brown phosphate film are obtained in these range of technological parameters and the best apearace and corrosion resistance phosphate film are gained in the phosphate solution with pH2.34and 30℃in 16 minutes.The appearance,micro-cristal appearance,the resistance to CuSO4 drips and NaCl solution are checked3.The influence of pH value and temperature to the process of phosphating was investigated by open circuit potential-time curve.The results showed that the higher the temperature and pH value were,the faster the open circuit potential became stable, and the larger the difference value between the intial open circuit potential and the final stable open circuit potential is,the better the corrosion resistance of the phosphate film obtained.In adition,the process of golden-brown phophating could be devided into four stage,the first stage last-ed from 0 to 80 seconds,the open circuit potential decreased sharply,the second stage lasted from 80 to 280 seconds,the open circuit potential decreased slowly,the third stage lasted from 280 to 460,the open circuit potential reached stable, the final stage started from 460,as phosphating continuing,the open circuit potential increased slowly.4. The normal temperature and non-sludge poshahte solution of blue phsophating was obtained by orthogonal experiment and singal factor experiment.the prescription and technological parameters of this phosphate solution are as follows:ZnO 4.0g/L,H3PO412ml/L; Mn(H2PO4)2·2H2O 1.2g/L,second accelerator 3.7g/L,Ni(NO3)23.1g/L,accelerator 1.3 g/L, cupric salt 0.07g/L.Technological parameters:pH 2.5～3.0,phosphating temperature 23～31℃, phosphating time 15min.5.The appearance, film weight,micro-structure,the resistance to salt solution and CuSO4 drips of blue phosphate film which gained in optimization phosphate solution in best technologica parameters were tested.6.The process of blue phosphating were investigated by open circuit potential-time curve and SEM,The final content and phase of blue phosphate film were analysised by EDS and XPS7.Contrast blue phosphating phosphate solution,normal oxidation solution and high temperature oxidation solution of steel from process of technics production cost treatment fluid cost and poisonous of these solution, Also contrast the corrosion resistance of blue phosphate film,normal temperature oxidation film and high temperature oxidation film.The results showed that this phosphate solution which can produce blue phosphate film in the surface of steel could instead normal temperature oxidation solution and high temperature oxidation solution and have the value of industrial application...