Thread: Corrosion - any ideas how this happened??

Originally Posted by macbac

eat at own risk should be labled on the can.

I agree. I'd bring that food up to the rolling boil for at least 2mins before consuming.

Aluminium & steel aren't good companions. That is why, in LRs, the joints are insulated.

Aluminium is resistant to corrosion because it forms a stable oxide layer. Break through that layer and corrosion is rampant.

Dis-similar metals. Always a place to watch for corrosion on light aircraft too

Originally Posted by Bushwanderer

Aluminium & steel aren't good companions. That is why, in LRs, the joints are insulated.

Aluminium is resistant to corrosion because it forms a stable oxide layer. Break through that layer and corrosion is rampant.

Marvellous. Now I'm going to be paranoid about the SIII for "stable oxide layers". What do they look like?

Originally Posted by Panda

Marvellous. Now I'm going to be paranoid about the SIII for "stable oxide layers". What do they look like?

Its just the aluminium oxide coating that covers aluminium. Aluminium is highly reactive, but it forms an Aluminium oxide coat extremely quickly which doesn't react with much and it forms a physical protective barrier.

Originally Posted by Slunnie

Its just the aluminium oxide coating that covers aluminium. Aluminium is highly reactive, but it forms an Aluminium oxide coat extremely quickly which doesn't react with much and it forms a physical protective barrier.

Yea, but what colour is it? How can I tell if it's formed a coat? Is it some sort of colour coding? Like brown for steel, green for aluminium? How big a barrier is it? Where will it form on my SIII?

Originally Posted by Panda

Yea, but what colour is it? How can I tell if it's formed a coat? Is it some sort of colour coding? Like brown for steel, green for aluminium? How big a barrier is it? Where will it form on my SIII?

Paint starts to bubble and lift. Unlike rust on steel there is no real discolouring.

Originally Posted by Panda

Yea, but what colour is it? How can I tell if it's formed a coat? Is it some sort of colour coding? Like brown for steel, green for aluminium? How big a barrier is it? Where will it form on my SIII?

When you look at a piece of aluminium, what you're actully seeing is Aluminium oxide, not aluminium. They are the same colour, though the oxide I think can go whitish depending on what it is exposed to. Every bit of aluminium on your SIII was totally covered in Aluminium oxide before the factory even got paint on it, it happens quickly. The oxide layer is good because it protects the aluminium and thats the end of the oxidising process - its not like rust that continues to decay the steel.

Green is more a copper corrosion colour