Development Of High Efficiency Hydrate Metal Electrochemichal Degreasing Solution For Steel Parts

In order to prevent corrosing and rusting of steel parts,it is common to apply a oil film on the surface of steel parts.The oil film will reduce the use efficiency of the steel parts,so it needs to be removed during using.Based on the properties of the oil film and the chemical and electrochemical properties of the steel strip and the high-speed production requirements of the industry,this paper selected the electrochemical degreasing method of the alkaline system for degreasing.The main components of the oil film include mineral oil,animal and vegetable oil,animal and vegetable oil can be removed by saponification reaction with alkaline substances,and the stable mineral oil is usually not reacted with alkaline substances and can be emulsified with surfactants to remove oil.Electrochemical degreasing fluids usually include strong alkaline materials,complexing agents,penetrating agents,emulsifiers,and so on.In industrial production,in order to reduce production costs and increase production safety,it is usually necessary to strictly control the production process conditions.In this paper,more than twenty kinds of surfactants were selected,and their physical and chemical properties such as cloud point,HLB value,CODCr,foam performance,and oil removal rate were determined.Selected fatty acid methyl ester polyoxyethylene ether sulfonate(FMES),grape alkyl glucoside(APG1214)and fatty alcohol polyoxyethylene ether 9(AEO-9)as the surfactants of degreasing,which have good emulsifying power,long service life,short response time and meet the requirements of industrialized rapid production.The surface tension and oil removal rate of single surfactant and mixed surfactant were determined by single-factor test and orthogonal test to determine the optimal concentration of three surfactants.Refer to JB/T4323.2-1999 "Test method for high-efficiency water-based metal cleaning agent",alkaline substances include anhydrous sodium carbonate,sodium polyphosphate,and sodium metasilicate pentahydrate.In order to reduce water pollution and cleaning difficulty,ammonium benzoate was used instead of sodium polyphosphate,sodium citrate was used instead of sodium metasilicate pentahydrate for degreasing.The single-factor and orthogonal tests of anhydrous sodium carbonate,ammonium benzoate,and sodium citrate were performed respectively to determine their oil removal rate and p H value,so as to determine their optimum concentration.Since the electrochemicaldegreasing needs to be carried out under strong alkaline conditions,the addition of Na OH to the alkaline degreasing solution is used herein to determine the oil remove rate and p H value at different concentrations to determine the optimum concentration.Since a large amount of foam is generated when the degreasing solutiont is in effect,a certain amount of defoaming agent is usually added to the degreasing solutiont.Through the analysis of the commonly used defoaming agents in the industry,a suitable defoaming agent was selected and its defoaming capacity at different times and concentrations was determined to determine the best use concentration.A single factor test was performed on the three process conditions of degreasing time,degreasing temperature,and current density,and the oil remove rate of each process condition was determined to obtain the best use range.The degreasing solution is used to electrochemically degrease the steel strip,and the SEM,corrosion resistance and water contact angle analysis and comprehensive performance measurement show that this degreasing solution has a good degreasing effect.The results show that the degreasing solution has the advantages of good degreasing performance,poor foaming performance and low pollution.The obtained galvanized steel sheet has good corrosion resistance,uniform surface and less plating defects.