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Rusting problem

We have got peculiar problem the parts which we are electroplating are made out of crca sheets and the deposition is provided on to the parts over 5 micron the packaging is done in the linen cartoons with lots of silica gel packets are put in after packing the cartons are stretch wrapped but still we are getting the rust problem the salt spray test says the life 16 hrs. The part has blue passivation. Can you suggest what measures shall we take to tackle the situation. The position is desperate we have done everything we knew.

Tarachand
chemist - Mumbai, Maharashtra, India
2004

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Dear Sir,

The process you are explaining is the post mortem after plating. There could be various reasons which would lead to development of rust such as improper pretreatment prior to plating,improper drying, parts not being properly plated, etc. You should look into your process before packing and storage is carried out.

K.V. Phadnis
- Mumbai, Maharashtra, India
2004

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Dear Sir,

16 hours is all the corrosion resistance possible from zinc blue with 5 microns. If you are using pickled or HR sheet the resistance will even be less and you may see corrosion even sooner. All the Silica Gel in the world will not help if you spec your parts so poorly.

If plating thickness is not a problem, please ramp up the thickness followed by yellow or olive chromate. Or try Alloy Zinc Plating.

With best regards,

Khozem Vahaanwala
Saify Ind

Bengaluru, Karnataka, India

2004

I follow Vahenwala's reply.

V S Magesh
- Chennai, India
2004