Anti-corrosion protection

Alan_uk

A2OC Donor
I've just read the BBC article about the Bloodhound 1,000 mph record attempt car [or is it more a plane that's kept on the ground ;) ]. Besides use of titanium (very hard to work) it also mentions anodising the aluminium to protect it from corrosion, specifically salt in the salt beds in South Africa. Doesn't mention what the coating is but says it creates a "protective aluminium oxide layer about 1,000 times thicker.. but is still thinner than a human hair." http://www.bbc.co.uk/news/science-environment-32993861

So I thought I would check to see what is done on the A2. Answer is a

After the raw body shell has been finished and the heat treatment has been carried out, the body is cleaned and prepared with a 3-cation phosphating layer (Zn = zinc, Ni = nickel, Mg = manganese) that forms a bonding layer for the subsequent cataphoretic immersion painting (CIP).

CIP: After the phosphating process the body receives a cataphoretic primary coating, which provides an excellent protection against oxidisation. CIP primary coating produces a layer of paint up to 20 µm thick on the body.

I also read that
All fastening components that come into contact with aluminium are coated with Dacromet, Delta Tone or a similar coating to prevent contact corrosion. In addition these parts are coloured with a green lubricant on an alkyd resin basis to provide a clear distinction to normal fastening components.

Source: Audi A2 Body Construction and Function Self-study programme 239 http://forum.a8parts.co.uk/attachment.php?attachmentid=10544&d=1430156249 opens in external pdf reader

I do hope when our A2s are serviced they use the correctly coated bolts. I'm sure I read once that dealers are supposed to use different sets of tools when working on aluminium cars but I can't see that happening, especially with independents.

Over the years we've had a number of threads about corrosion and for many of us the 12 years warranty (for what it's worth) has ended or will end soon. Still, my A2 is looking far better at 11 years old than any car I've owned. And that's true for many members cars as well. Long may it continue.
 
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