Ah I see. But what about a thin adamantium coating like Wolverine's skeleton as others here have mentioned? People like punisher and daredevil have been able to life wolverine up before so a thin coating can't make tony's armour too heavy.
Well... I think Wolverine weighs around 300lbs.... given his build i'd think he should weigh about 200lbs at the most..... so it seems adamantium is pretty heavy but nothing that the Iron Man armour couldn't handle easily enough.
Ok... Look what I found in a handbook, Apparently he weighs 195lbs without adamantium and 300lbs with it:
That should give a basic idea of how much it might weigh if coated over IM's armour..... probably wouldn't make much difference at all.... it's just much harder to work with
Well he doesn't have to coat the entire body (it would probably be impossible to move if he coated the joint sections). But coating on his chest plate, helmet, leg guards and gauntlets would give him insane durability.
I'd say one of the few things that can truly damage Ironman's armor (besides repeated Hulk-level punches) are sophisticated adamantium weapons. I recall a pretty cool comic book (Marvel fanfare #22), where Doctor Octopus uses adamantium tentacles to literally tear the armor to pieces.
However thats adamantium beta, which is not the same as normal adamatium.
The reason some one like stark does not uses adamatium is due to the fact no one really knows how to create it out side the much cheaper and far less durable 2ndry adamatium.