Plating this Magnesium Metal Layer onto Carbon Steel

What is in the tank, its pressure and temperature?

There are lots of ways to do it.

How good a job do you want and how long does it have to last?

If the inside of the tank is etched you could just throw in some magnesium powder, add some ball bearings of appropriate size, fill the tank with C O² and seal the tank. Then rotate the tank. This hammers the soft metal into the etched surface.

You could try Sherardising.

http://en.wikipedia.org/wiki/Sherardising

You could even shrink fit a solid Mag liner or a foil liner.

The purpose size and life expectancy would be useful information.

By the way magnesium burns beautifully and it is great fun to watch some body try to put it out with water. Dangerous but interesting.

BAB

Magnesium is too active a metal to elctroplate out of an aqueous solution. Mechanical bonding as others have suggested looks to be the most likely method. What thickness of coating? what other properties you looking for?

Milo