Purpose of stainless steel chromium plating:
(1) Improved rust resistance. Martensitic stainless steel in stainless steel such as 2Cr13, 3Cr13, 9Cr18, 9Cr18MoV, Cr17Ni2 and other chromium 12%(wt) more than, but does not contain nickel or a small amount of nickel stainless steel, in the atmosphere will change color and corrosion. Decorative chrome or hard chrome plating is available for improved corrosion resistance.
(2) Improve the appearance. Stainless steel products and electroplating decorative chromium together, there are obvious differences in appearance, in order to make the appearance of the same color, also often stainless steel chromium plating.
(3) improve the hardness of stainless steel. In particular, the hardness of austenitic stainless steel is low, although the corrosion resistance is better, but it is not wear-resistant, so hard chromium plating is needed to improve the hardness, increase wear resistance, and prolong the service life.
(4) milky chrome layer. In order to obtain a soft and not dazzling coating, such as in stainless steel measuring tools (ruler, micrometer, etc.) on the scale or disk can be plated with milky white hard chrome, both decorative and optical requirements.
General method of stainless steel chromium plating (1) stainless steel chromium plating can be used before activation – pre-nickel plating method to obtain the bottom layer, and then chromium plating on the nickel layer, can obtain a good bonding force of chromium layer.
(2) low current cathode activation – step current charge – impact current chromium plating – normal current chromium plating to the required thickness of the slot, so that the four stages of treatment and electroplating can get good adhesion coating.
(3) Potassium iodide cathode treatment. Cathodic treatment is carried out in 5%-10%(wt) sulfuric acid solution containing 1g/L potassium iodide. Voltage 6V, time 30s, temperature, room temperature, cathode current electrolysis, on the surface of the stainless steel surface to produce a layer of brown and black film, fully rinsed to remove sulfuric acid, leaving the brown film of stainless steel products into the chromium plating tank chromium plating, can obtain a very good binding force of decorative chromium or hard chromium plating. The brown film dissolves rapidly during chrome plating without noticeable contamination and without any deterioration of the original surface.
By ten stainless steel composition variety, different shapes, plating before the state is different, according to the actual situation, to take the appropriate process and process specifications, as well as special fixture.
