The Study Of Cathodic Electrodeposition Coating Pretreatment

In this article, the zirconium fluoride acid is the main agent in zirconium technology, zirconium fluoride acid hydrolysis reaction can form a stable chemical properties of the amorphous oxide film in the metal substrate surface, conversion film on zirconium products with metallic base material forms strong bonding force, rely on the combination of organic polymer and coating strongly, so as to obtain good performance of the surface of the metal film, to achieve excellent adhesion and corrosion resistance. Zirconium solution does not contain phosphorus, and other heavy metal ions, low operation temperature, short operation time, it is important to form the former processing conversion coating and metal substrate not only has good adhesion, and has strong combining ability and paint, so that the workpiece reach the goal of good anticorrosion.Through zirconium film appearance state, bottom corrosion and hang ash zirconium we explore cathodic electrodeposition pretreatment process of main parameters, including the concentration of the A is5%, the concentration of the B is5%, pH=3.5, zirconium time for2min, zirconium temperature for more than5℃. Then the parameters for cathodic electrodeposition were discussed. According to the appearance of the electrophoretic coating and coating film thickness we analyse each parameter of the test results:18%solids, pH=6.0+0.2, the temperature of30℃, soft time of15s, working voltage is120v, electrophoresis time is2min in each test film, appearance and film thickness can achieve ideal results. Then through orthogonal test, according to each artifact electrophoresis paint film after the acid resistance of copper ions accelerated salt fog test, to obtain a series of parameters of the cathodic electrophoresis for20%solids, pH=6.0±0.2, the temperature of30℃, soft time is10s, working voltage is140v, electrophoresis time of2min. The results of orthogonal test for verification of the resistance to salt spray test, salt spray test100hours of acidic copper ions accelerated after the little loss. Swim through force of up to45.6%.Zirconium in cathodic electrodeposition pretreatment can replace phosphating treated group were compared in laboratory, the results found that both salt fog corrosion resistance ability and swim through force, zirconium solution can achieve close to the effect of the phosphating liquid, and through some car manufacturers online use further confirmed that the current of cathodic electrodeposition coating on zirconium in liquid can be used to replace phosphating liquid.