Research On Mechanism Of Nano Electriless Composite Plating On Cast Iron By Ultrasonic Wave

Cast iron is an important kind of engineering material. Good surface performance of castiron is needed with the development of society and science, so good measures of protectingthe surface of cast iron are needed. Electroless plating is widely used because of low energyefficiency, low cost, pro-environment and simple technics. Electricity is not required in thewhole process of electroless plating. Metal ions is reduced in use of reducing agent. Themetal got by redox reaction deposites on the cast iron surface.By orthogonal experiment, lactic acid 20ml/L, citric acid 25g/L, succinic acid 9g/L andAcONa 15g/L form the best plating liquid, and 60W, 60℃, pH6.2 and Al₂O₃ concentration10g/L form the best technological parameters. The results show that plating got by ultrasonicelectroless plating is more homogeneous and more compact compared with conventionalelectroless plating.The plating performance changed regularly with the ultrasonic power and temperatureby ultrasonic electroless plating Ni-P-Al₂O₃. Deposition rate reached to 11.0 mg /h/cm². Thehardness of plating reached to 511.3HV. The dropping time was prolonged 1801 seconds.When the tempering temperature was 300℃, the plating started to formed [Fe,Ni]. Thedropping time reached to the highest value 1909s. When the tempering temperature was400℃, the plating achieved crystallization and dissolved out Ni₃P. The hardness reached tothe highest value 552HV. When the tempering temperature was 500℃, the plating dissolvedout Ni that leading to the hardness decreasing. When the tempering temperature was 600℃,The plating was oxidized and the hardness and the dropping time decreased obviously.