I was at a 'It's a Beautiful Day' concert in 1970, on acid, so I guess I'm an Electrochemist responding to Andrew's request! Please, no calls until after 1300 hrs!! Miguel
On Sun, Aug 16, 2009 at 9:39 AM, Alistair Bell<albell@shaw.ca> wrote: > 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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