Aluminum 2219 Tank

A while back, I was experimenting with joining an aluminum square 0.125" thickness to a copper square, also 0.125" thickness. Without having sophisticated welding techniques in my home shop, I was needing to form an ohmic contact on these 1" edge pieces.

Direct application of aluminum braze rod did not stick, however, when I tinned the copper with resin core solder, the braze rod worked by dissolving solder into the joint where the Alumiweld was wetting the aluminum. The joints lasted long enough for my tests, which involved "domino" like stacks with phonon cell media between the dominoes. The alkaline nature of the crystals played havoc with the welds eventually, though.

It is possible also to purchase aluminum clad with copper (as an overlay through the implosion forming process). This is highly useful in electric bus bars.

I presume on a rocket fuel tank, having high tensile and hoop stress strength with low ductility is a good thing, or they would not be using it for that. Are there not separate vessels within the big tank, one for hydrogen, the other for oxygen?