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Neutral salt spray resistance for zinc plating with clear passivation
We have analysed a component plated with Zinc plating and clear (blue) passivation for neutral salt spray as per ASTM B117 [affil. link to spec at Techstreet] and didn't find white rust even after 450 hours. Is this possible? What are the factors make this different?Narasimhun Parthasarathy
auto electricals - Chennai, Tamilnadu, India
First of two simultaneous responses -- 2006
Any thing is possible, at least on a one time basis. Assume that it is a thick coating that has been very well done with an excellent blue chromate and has been handled with care.. My real guess is that they put a very thin coat of clear lacquer or wax on it.James Watts
- Navarre, Florida
Second of two simultaneous responses -- 2006
Dear Mr Parthasarathy;
Yes its possible with a combination of Alloy Plating, amazing chromate products and really good topcoats.
My plating shop commits 250 hours to white rust for Zinc but delivers much more!
Bengaluru, Karnataka, India
1. I would check all the operating parameters of the salt spray cabinet.
2. 450 hours can be reached with a zinc alloy (zinc cobalt/iron/nickel) with an organic sealer on top of it.
It is a Zinc plating with clear passivation having thickness of 10-16 microns. And please let me know the methodology to find out the presence of topcoat or sealant by any instrument/chemical test?Narasimhun Parthasarathy
autoelectricals - Chennai, Tamilnadu, India
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