Research And Analysis Of Electroless Nickel Plating Process In Acidic Solution

Fe-based material is one of the most widely used materials; however, iron is apt to rustiness when exposed in the air, which has a serious impact on its service life and range of application. In order to improve the performance of ironware, surface processing is often employed. For example, chemical plating can give a large improvement for Fe-based material and expand its usage in a big extent. Chemical nickel-plating layer has perfect properties especially on anti-corrosion, wear-resisting, electromagnetic screen, mechanical treatment and castability that it has been widely used in almost every area such as aerospace, automobile, electronics and computer, machining manufacture.In this thesis the definition, history and category were introduced in the first part, and the physical and chemical properties were given in the second part. The principle of chemical nickel-plating and the composition of solution for chemical nickel-plating were explained in the final part. In the experimental part, all steps of the technological operation for the plating on iron sheet such as pretreatment, preparation of the plating solution, determination of the stability of the plating solution, and baking before or after the plating, were discussed. Observation of the surface and the determination of the hardness on the plating-layer were performed after the plating. The effect of every composition in the plating solution on the deposition rate was also studied. The try of using urea as additive was adopted in the plating process, and a perfect technical formula for plating was got as the following:nickel sulfate (30g/L), sodium hypophosphite (35g/L), sodium acetate (15g/L), sodium citrate (25g/L), lactic acid (6g/L), sodium dodecyl sulfate (0.01g/L), and urea (1g/L). The average values at different pH or temperature were also determined and it was found that the optimal pH and temperature were5.0and80℃, respectively. Under these two optimal conditions, the plating rate was15.21μm/h. In the final part the processing of waste plating solution was studied. By designing reasonable experimental procedure the waste plating solution reached the standard for discharge to the environment, which could not only save resource but protect the environment from pollution.