▎ 摘　　要

NOVELTY - Electroplating zinc-cadmium alloy and coating hydroxy-graphene modified electrophoretic paint comprises preparing zinc-cadmium alloy coating, phosphating layer and hydroxy-graphene modified electrophoretic paint coating from the inside to the outside in sequence on the metal substrate. The zinc-cadmium alloy coating is prepared by potassium chloride zinc-cadmium alloy electroplating process: 30-50 g/l zinc chloride, 10-25 g/l cadmium chloride, 100-160 g/l complexing agent, 1.5-2.5 ml/l brightener, 25-35 ml/l adjuvant, pH is 6.5-7.5, the temperature of the electroplating bath is 15-35 degrees C, the current density of the cathode is 0.5-2.5 A/dm2, and the anode is zinc plate and separator. The complexing agent includes first component and second component. USE - The method is useful for electroplating zinc-cadmium alloy and coating hydroxy-graphene modified electrophoretic paint. ADVANTAGE - The method: obtains protective layer, which has high wear resistance and corrosion resistance; is suitable for preparing high corrosion resistance coatings in various strong corrosive environments; is designed to solve the strong corrosion of marine environment suffered by ships and offshore oil device in our country; and provides set of novel technical solutions. DETAILED DESCRIPTION - Electroplating zinc-cadmium alloy and coating hydroxy-graphene modified electrophoretic paint comprises preparing zinc-cadmium alloy coating, phosphating layer and hydroxy-graphene modified electrophoretic paint coating from the inside to the outside in sequence on the metal substrate. The zinc-cadmium alloy coating is prepared by potassium chloride zinc-cadmium alloy electroplating process: 30-50 g/l zinc chloride, 10-25 g/l cadmium chloride, 100-160 g/l complexing agent, 1.5-2.5 ml/l brightener, 25-35 ml/l adjuvant, pH is 6.5-7.5, the temperature of the electroplating bath is 15-35 degrees C, the current density of the cathode is 0.5-2.5 A/dm2, and the anode is zinc plate and separator, the complexing agent includes first component and second component, where the first component includes nitrilotriacetic acid and glycine in a mass ratio of 7:(4-6), the second component includes citric acid, tartaric acid, gluconic acid and/or malic acid, the complexing agent includes first component and second component in a ratio of 7:(6-10), and the first component and second component are uniformly mixed together to obtain the complexing agent. The brightener includes third component, fourth component, fifth component, sixth component and seventh component. The third component is alpha -vinyl-N-propanesulfonic acid pyridine inner salt. The fourth component is o-chlorobenzaldehyde. The fifth component includes 3-methoxy-4-hydroxybenzaldehyde, 3,4-dimethoxybenzaldehyde, and/or 4-methoxybenzaldehyde. The sixth component includes propynol salt, propynol ethoxy ether, propynol propoxy ether, N,N-diethylpropynamine, N,N-diethylpropynamine formate, and/or N,N-diethylpropynamine sulfate. The seventh component is butyl ether ammonium salt. The brightener is prepared by uniformly mixing 200 ml deionized water and 400 ml isopropanol, adding 30-60 g third component, 20-30 g fourth component, 30-50 g fifth component, 100-150 g sixth component, and 40-70 g seventh component, stirring until the components are completely dissolved, and adding water to 1000 ml to obtain the brightener. The auxiliary agent comprises small molecular weight polyacrylamide, sodium benzoate, sodium dimethylbenzene sulfonate, and condensate composed of ethylenediamine and epichlorohydrin, prepared by adding 50-80 g small molecular weight polyacrylamide, 30-60 g sodium benzoate, 50-80 g sodium dimethylbenzene sulfonate, 30-70 g ethylenediamine and epichlorohydrin condensate, 30-70 g polyoxyethylene ether phosphate, and 600 g water, stirring to dissolve, then adding water to 1000 ml to obtain the auxiliary agent. The hydroxy-graphene modified electrophoretic paint coating is prepared by cathodic electrophoretic coating process of 300-350 g/l electrophoretic paint concentrate, 150-200 g/l hydroxygraphene filler, and 6-15 g/l pigment, the operating temperature is 25-30 degrees C, the cell voltage is 30-100 V with the coated workpiece as the cathode and 316 stainless steel plate as the anode. The hydroxygraphene filler includes hydroxygraphene, aqueous silane polymer and aqueous polyurethane resin, and prepared by uniformly stirring 250-350 g 1 wt.% nano-scale hydroxygraphene gel, 150-250 g aqueous silane polymer, 30-60 g aqueous polyurethane resin, 300 g deionized water, then adding water to 1000 ml to obtain hydroxygraphene filler, which is used after placed at room temperature for 7 days, and the pH of the 1% nano-scale hydroxygraphene gel with mass fraction of 1% is 7-8.