Andrew, your'e wrong here.
It is called galvanizing, whether hot dipped or electroplated. Modern car makers do use it to some degree or another. But the important thing you do not understand is the protective effect of galvanizing has *everything* "to do with electrolysis". Do more study, you'll find how that the zinc coating acts as the sacrificial anode when applied to metal, so much that even if the coating is broken it still protects the un-covered steel. Mind you it works better on simple structures like anchor chains, cleats, etc. Less well when the structure is complicated and there can be localised extreme conditions, as in a car, or a fastener through differing materials, stray currents at moorages, etc. Galvanizing works, hot dipped more than electroplated (hot dipped has more zinc applied).
Alistair
On 16-Aug-09, at 1:48 AM, Andrew Grebneff wrote:
> But VW and the other car companies did the > next best thing. They started building cars in the 80s with steel > panels > coated with a sacrificial anode - it's called zinc plating. This is NOT galvanizing. Galvanizing is electroplating... what you end up with is a thin coat of zinc metal (visible as flattened crystals on the surface) over the base metal. What the carmakers do is to treat the metal sheet with some chemical, which leaves a residue on the steel. This is rather ineffective. Thye purpose of galvanizing has nothing to do with electrolysis. What it does is merely to keep the steel surface completely away from water. Nio water, no rust (one form of iron oxide, I think a hydrous one; as a mineral in nature I think it is limonite). |
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