Researches On Surface Metallization Of Abs Plastics And Anticorrosive Property Of Coating Passivation

The surface metallization processes combine inherent performances of ABS plastics,such as thermal stability,excellent mechanical strength,and high resistance to chemical reagents.Metallized plastics will also bring about the characteristics of the metal,such as conductivity,magnetic shielding,abrasion resistance.It is increasingly high required for low-cost,lightweight products in modern industries.The metallization processes of plastics have been widely used in electrical and electronic,automotive,computer body parts,office equipments,machineries and other industries.The traditional processes contain chromic acid etching and sensitization-activation treatment,and the cohesive strength between coatings and substrate is low,toxic hexavalent chromium passivation is also adopted in this case.It is of great significance to develop non-palladium treatment and chromium-free passivation technology.Benefit from the molecular grafting and chemical spraying processes,so that we have achieved excellent adhesion strength between silver coatings and ABS.On the basis of silver films,the electrodeposition of copper/nickel plating technologies were studied,and finally,by means of plating nickel sealing-chromium-free passivating treatment,the corrosion resistance of the good composite coatings was prepared.The mechanism of chromium-free passivation filming and the corrosion behavior of nickel seal-chromium-free passivation coating were studied,the main conclusions are as follows:(1)ABS plastics were modificated by P-TES and N-TES molecular pre-treatments,and nitrogen groups had been combined with carbon hydrogen bonds in the UV light conditions.N-TES is bonded to P-TES through polycondensation,and N-TES can self-assemble continuously and eventually grafted onto the ABS.The silver plating layers prepared by the chemical spraying process had good bonding with the substrates.The average peel strength reached 8 N/cm.(2)After the chemical spraying of ABS,the pyrophosphate copper plating and the copper sulfate plating process were respectively studied.Two optimum technological conditions were obtained by orthogonal experiment.The sulphate copper plating was compact in various process conditions,and the binding force is maintained at a high level.The corrosion resistance of the pyrophosphate copper layers was lower than that of the sulfate copper plating layer.The corrosion potential of semi-bright nickel coatings and bright nickel coatings were respectively-0.240 V and-0.352 V.Because of the potential difference between the two nickel coatings,a galvanic cell was formed between the two layers.(3)The composite electrodeposition processes were carried out on the double nickel layers.The minimum corrosion current density of the 4 g/L Ni-SiC composite coatings was0.860?A/cm~2.The corrosion current density of the chromium-free passivation films with more positive potential were 0.354?A/cm~2.Neutral salt spray test showed that chromium-free passivation film did not appear obvious rust.Nickel seal-micro-porous chromium-free passivation processes have excellent corrosion resistance,anti-oxidation and anti-discoloration capabilities.