Metal corrosion signage is broadly divided into concave signage. Convex signage and convex-concave word combination of these three kinds of signage. Corrosion of the basic requirements of the sign: beautiful pattern. Clear lines. Depth is appropriate. The bottom surface is flat. Full color. Even drawing. Consistent surface color. The characteristics of corrosion signage: weather-resistant, solvent-resistant; even if the paint falls off still has the function of the nameplate. Strong solvent resistance; even if the paint is peeled off still has the function of the nameplate. Stainless steel is a special material, it has good resistance to corrosion of atmospheric and freshwater media performance, and can be drawn, corrosion, polishing to obtain a good decorative effect. However, stainless steel corrosion than copper, aluminum plate is much more difficult, the fastest corrosion method is electrochemical corrosion also known as electrolytic corrosion. Due to the electrochemical corrosion in the signage corrosion will make the ink off, so the signage is not applicable to electrochemical corrosion, especially the fine pattern. We only choose chemical corrosion. Chemical corrosion can be roughly divided into two kinds: strong acid corrosion and ferric chloride corrosion. Due to the complexity of the formula of strong acid corrosion, maintenance difficulties, and produces a lot of fumes, polluting the air is harmful to human beings, no purification equipment manufacturers can not be used. Ferric chloride corrosion formula is simple, easy to maintain and regeneration.
Ferric chloride corrosion of stainless steel formula: ferric chloride, active agent, water. Formulation of ferric chloride in the boehm degree should be maintained at about 42, per liter of ferric chloride solution add active agent 0.8-1.2 ml. The formula corrosion out of the stainless steel bottom flat and smooth, no black passivation film and pitting.
The factors that affect the corrosion of stainless steel by ferric chloride solution are as follows:
a. The effect of concentration. Chemical corrosion we also call microcell corrosion its redox potential the more positive, the relatively faster the corrosion rate. As the concentration increases, the redox potential becomes positive corrosion rate increases. Industrial-grade ferric chloride because of its purity is not high, the redox potential is more negative, only when the Baume degree reaches 42 or more redox potential to achieve the corrosion of stainless steel requirements.
b.PH value of the solution on the corrosion rate of the impact of low PH value, powerful in the corrosion of stainless steel; PH value is too high ferric chloride hydrolyzed into iron hydroxide precipitation, the loss of corrosion. In the production of corrosive solution used to a certain extent should be adjusted to its PH value.
c. The influence of the temperature of the corrosive solution. The higher the temperature of the corrosive fluid, the faster the corrosion rate. But taking into account the ability of corrosion-resistant ink, the temperature should be controlled between 30 - 40 ℃ is appropriate.