Plating Pretreatment Process
Clean and plating state level is to obtain high-quality surface coating fundamental guarantee, rough surface oil can not get a smooth, bright, a good combination of strength, corrosion resistance and strong coating. Practice has proved that the coating spalling, blistering, piebald, corrosion resistance and poor are often caused by improper plating pretreatment.
Galvanized seamless steel pretreatment process including polishing, degreasing, etching and pre-plating processes.
(1) degreasing liquid degreaser capable of removing grease plated surface, so the surface of the plating bath has good wetting properties. Degreasing liquid cleaning agent is a metal, mainly by NaOH, Na2CO3, Na2SiO3, and emulsifiers and other components.
(2) etching solution capable of etching solution to remove the surface oxide passivation film and plating that the plating surface activation. Etching solution of acidic and alkaline etching solution etching solution, extensive application of acid etching solution by acid, corrosion inhibitor, surfactant.
(3) polishing liquid slurry coating makes the surface smooth glossy, minutes and electrochemical polishing liquid chemical polishing liquid two kinds. Chemical polishing liquid from a variety of acid, emulsifier and corrosion inhibitor composition, electrochemical polishing liquid from the acid, corrosion inhibitors, emulsifiers, oxidants and other components.
(4) Pre-plating bath can be prevented in some immersion plating solution, the substrate was dissolved and replaced with a poor adhesion of the coating. Different metal bath pre different composition. The most used is the pre-nickel plating, copper plating, chrome and other pre-solution. Aluminum and its alloys, magnesium and its alloys before pre-plating but also heavy metals leaching.