Study On Extending The Life Of Electroless Nickel Plating And Electroless Composite Plating Solution

The electroless plating Ni-P is surface treating technology using self-catalyze reduction, which has been applied in many industrial fields in recent half century. Based on this, by changing the matrix of metal and dispersed particles, to obtain good resistance to wear, self-lubricating ability, heat-resistant ability and special decorative ability etc., the electroless plating composite coating also has a wide range of applications.However, the key of electroless plating nickel and electroless composite plating is the formula of the bath and the way of maintenance. Extended the bath life can effectively decrease production costs and pollution releases. Therefore, the study on extending the life of the plating bath is great significance.The electroless plating Ni-P was taken through three different plating methods in this thesis, that including non-additive solution plating, adding directly addition liquid plating and interval fetching fluid method plating, the properties of the coatings were tested. According these properties, the bath life can be assessed. The electroless Ni-P/Al₂O₃ composite plating was taken using the interval method. The properties of the Ni-P/Al₂O₃ coatings were tested. The results show that:Taking the non-additive solution plating, the bath of the electroless plating Ni-P deterioration occurred with the organic acids decomposition, alkali metal ion and acid radical ion concentration increasing. The deposition rate of the coating decreased about 50% after plating three times.Taking adding directly addition liquid plating, the bath of the electroless plating Ni-P failure has alleviated in a certain degree. The rate of change of the coating thickness is small. But only plating 6 times, the deposition rate is from 12.2μm/h decreased to 3.9μm/h. Taking the interval fetching fluid method plating, the bath of the electroless plating Ni-P can be used continuously up to 10 times. The coatings have good properties. The rate of change of the thickness and the micro-hardness of the coatings is very small, the deposition rate steady at 12μm/h.Taking the interval fetching method plating, the bath of the electroless Ni-P/Al₂O₃ composite plating can be used continuously up to 10 times. The micro-hardness of composite coating can reach HV700, the rate of change of the coating thickness and micro-hardness is very small, the deposition rate is about 7μm/h and stable.The porosity of the electroless Ni-P coatings and the electroless Ni-P/Al₂O₃ composite coatings, taking the interval fetching fluid method plating, is very small, and the corrosion resistance of the coatings is good. In summary, taking the interval fetching fluid method plating to take the electroless plating Ni-P and electroless Ni-P/Al₂O₃ composite plating, can effectively extend the bath life, and the coating has good properties.