The Stainless Steel Plating Pretreatment Process is Analyzed
Stainless steel in the air is easy to passivation, generates a density of passivation film, the passive film has good corrosion resistance. With the development of industrial technology, the application of stainless steel expanded rapidly, which leads to the increasing demand for functional plating on stainless steel.
The difficulties of the stainless steel plating on stainless steel on the bottom of the plating, and the difficulty lies in the pretreatment of stainless steel bottom plating. If mishandled, before often lead to coating layer, peeling, fall off wait for a phenomenon.
Concentrate on high precision, hard metal surface treatment in 12 years of JieChang electroplating factory, said: stainless steel plating pretreatment of the difficulty is how to eliminate the passivation layer on the surface of the stainless steel substrate surface activation completely.
Introduce the main process of the stainless steel plating pretreatment below:
(1) organic solution soaking degreasing
Part of the stainless steel parts can’t electricity method of chemical degreasing, because of some stainless steel parts after electrochemical degreasing, the surface near-black hair, which USES pickling also cannot make its become shining surface. In order not to damage on the surface of the stainless steel bright state, with industrial gas scrubbing of the surface oil pollution, first into chemical degreasing process again after cleaning.
(2) chemical degreasing
Stainless steel parts to be included in the tub with an industrial cleaning agent (general temperature is 50-70 ¡æ), can be equipped with ultrasonic to thoroughly remove oil on the surface of the parts; Oil removal time control for the clean surface oil.
(3) the acid pickling
In the process of stainless steel plating pretreatment, acid pickling is an indispensable process. Because acid can remove the rust on the surface of the stainless steel and passivation film, make it exposed on the surface of the matrix, and improve the adhesion strength of the coating.
(4) activation
Activation of the purpose is to remove the oxide film on the surface of the stainless steel, make its surface activation, to ensure sufficient adhesion coating and stainless steel substrates. The activation process has impregnated activated and cathodic activation. After the test showed that the stainless steel impregnated activated, make its surface passivation membrane quickly remove, electrochemical plating processing, then quickly generate a layer of coating, the coating and the adhesion of stainless steel.
(5) plating
Parts after entering precoated trough, do not electricity, park after 2 ~ 3 minutes, again electrify pre-plating processing. Stainless steel surface oxide layer formation rate is very fast, after chemical activation, is likely to grow a layer of oxide film on the surface. Therefore, when the plating soaks in the solution, first let the solution of hydrochloric acid on the surface activate and parts again at the chemical adsorption of nickel ions in the solution process, again electrifying, generating a layer of the thin nickel layer.
(6) Nickel plating
Immediately after plating, stainless steel parts are not clean in the pre nickel plating tank in the plating processing, so as to guarantee the coating with good adhesion. After pre-plating nickel with flowing water washing twice for subsequent electroplating again.
Stainless steel parts plating pretreatment process, the activation, and pre-plating process are very important. By chemical activation with pre-plating pretreatment methods to remove passivation film on stainless steel parts, make its surface to generate a good coating layer adhesion, so as to realize the stainless steel base material on a variety of metal plating.