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Steel is widely used in industry, but is also a great loss of corrosion, therefore, study the way to improve corrosion resistance of the steel is of great significance to conserve resources. Electroless plating technology is an important way to improve the steel corrosion resistance. Suitable rare earth elements added to the chemical plating solution to increase the stability of the bath, and to extend the bath life; reduce the plating temperature, the faster chemical deposition; improve the corrosion resistance of the coating. First, the present acidic electroless nickel plating solution for electroless plating, the results show that the deposition rate increased with increasing temperature and will gradually decrease to a certain extent, plating phosphorus content and pH value has been reduced. By orthogonal experiment method and visualization experiments comparing the resulting chemical nickel plating: nickel sulfate 25-30g / L, sodium hypophosphite 25-30g / L, sodium acetate, 5-10g / L , citric acid, 15-20g / L lactate at 5-10 g / L, and succinic acid 3 g / L, and the thiourea 1-2mg / L, and sodium hydroxide q.s., plating temperature 84-88 ° C, the plating pH value 4.5-5.0 plating time 1h. Of SEM, EDS, XRD coating structure were characterized by few pores of uniform coating, corrosion resistance stronger than uncoated steel. Secondly, on the basis of the optimum conditions derived above, add the appropriate amount of rare earth elements lanthanum in the electroless plating solution for electroless plating process and performance. Experimental Lanthanum optimal dosage 15mg / L. The system plus lanthanide bath, studies show that when the temperature reached 81 ° C, the deposition rate reaches the maximum, and in extremely short temperature change, plated speed rise speed quickly, shortening the time of plating. Thus, the addition of RE can reduce the plating temperature, saving energy, reducing costs. Then, in the bath system plus lanthanide optimize the chemical plating process conditions as an index to the stability of the bath and the deposition rate. The results showed that the bath stability increases with increasing pH, enhanced with increasing temperature, a reduction in erratic changes, with the nickel-phosphorus ratio increases with the increase in lactate concentration and enhanced with the increase of the concentration of sodium acetate The big first stable weakened. By orthogonal experiment to study the proportion of citric acid and lactic acid, buffer concentration of sodium acetate and plating time of deposition rate. The optimum conditions are: Nickel sulfate 25-30g / L Sodium hypophosphite 25-30g / L, and sodium acetate, 12-25g / L, citric acid 5-10g / L, and lactic acid at 15-20 g / L, succinic acid 3 g / L, of lanthanum oxide 10-20 mg / L, thiourea 1-2mg / L, an appropriate amount of sodium hydroxide, plating temperature of 78-82 ° C, Shi-plated pH of 4.5-5.0, plating time 1h . Finally, the use of polarization curve test coating corrosion resistance, blank specimen, the corrosion potential of the electroless plating nickel-phosphorus plating of electroless nickel-phosphorus add Lanthanum order-597mv-443mV-371mV; current density of the order of 9.6 × 10-7A · cm-2, 1.4 × 10-7A · cm-2, 0.2 × 10-7A · cm-2. In order of decreasing corrosion current, corrosion potential is increased successively better corrosion resistance coating in the bath, add the appropriate amount of rare earth elements lanthanum.
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