I was hoping to do my floor / bulk heads in aluminium or steel.
Any clever ways to bond the ally plate to the round steel chassis without the metals reacting?
When I worked on jet fighters we plastered everything that had an ally-steel contact with a paste jointing compound to prevent electrolytic corrosion between the dissimilar metals. Can't remember the brand but a quick google search threw this one up and it looks similar:
http://www.llewellyn-ryland.co.uk/downloads/duralac.pdf
Without it the aluminium turned to white powder very quickly and the fighter jets tended to turn into smoking holes in the ground, which could be detrimental to your pension if you'd put the part together that failed.
Just as an example of what electrolytic corrosion can do, back in the mid eighties the ammunition that went in the aircraft guns started spontaneously exploding.
Luckily(?) it was the propellant that was detonating rather than the high explosive in the projectile, so it was a relatively small explosion with only a little fragmentation of the cartridge cases (which are about the size of a 250ml beer bottle). It would still spoil your day if you happened to be holding it at the time though.
It happened so often that we had to wear body armour, a face shield and kevlar gloves while handling the ammunition and loading the guns. Without getting too technical and breaching the official secrets act, the ammunition has a steel cartridge case with an electrically initiated brass firing cap set in the centre, which is isolated from the case by a plastic insulating ring.
After lots of head scratching by the boffins at the armament research lab they discovered the following: The ammunition was being manufactured for the British by the Italians to a German design. The specification sheet called for a particular type of varnish (shellac, made from recycled beetles, very green. Erm, brown, actually) to be applied over the base of the cartridge to prevent moisture from collecting between the case and the firing cap. If this were to happen, dissimilar metal corrosion would quickly turn the moisture into an electrolyte, making the cartridge into a ferrous/copper battery. Once sufficient potential built up in that battery the firing cap would initiate as advertised and the propellant would go bang, blowing the case apart.
Only the Italians didn't have any of the special varnish so they used something they saw a chap pasting on pizzas in a Bistro. Which was acidic and turned every cannon shell they produced into a time bomb. All for want of a Lira's worth of varnish.
But you tell the young folks that these days and they don't believe you, no they won't...
Oh, and welding's not so difficult. Give it a try, you might surprise yourself.
