Stainless steel is a special material. Its manufacturing process is much more difficult than copper and aluminum plates, but it has good resistance to atmospheric and fresh water corrosion, and it has a beautiful decorative effect after corrosion, polishing, and drawing. The fastest corrosion method for stainless steel is electrochemical corrosion, also called electrolytic corrosion. Electrochemical corrosion is not suitable for electrochemical corrosion, especially for fine patterns, because the ink will come off in the corrosion of the label. We chose the chemical corrosion of Sanlizhuang Craft Factory here. The main raw material of chemical corrosion here is ferric chloride. The following is the formula of ferric chloride corrosion of stainless steel:
Ferric chloride, active agent, water. The Baume degree of ferric chloride in the formula should be maintained at about 42. 0.8-1.2 ml of active agent is added per liter of ferric chloride solution. The stainless steel bottom surface corroded by this formula is smooth and smooth, without black passivation film and pitting.
The factors that affect the corrosion of stainless steel by ferric chloride solution are as follows:
a. Effect of concentration. Chemical corrosion We also call micro battery corrosion. The more positive the redox potential, the faster the corrosion rate. As the concentration increases, the redox potential becomes positive and the corrosion rate increases. Because of its low purity, the industrial-grade ferric chloride has a relatively low redox potential. Only when the Baume degree reaches above 42 can the redox potential meet the requirements of stainless steel corrosion.
b. The effect of pH value in solution on corrosion rate. Low PH value, which is strong for the corrosion of stainless steel; too high PH value, the ferric chloride will be hydrolyzed to the precipitation of iron hydroxide and lose the corrosion effect. The pH value should be adjusted to a certain extent in the production of corrosive fluids.
c. Influence of the temperature of the corrosive solution. The higher the temperature of the corrosion solution, the faster the corrosion rate. However, considering the resistance of the corrosion-resistant ink, the temperature should be controlled between 30--40 ° C.