In the third book of the Chinese version(beginning of the second
book "Ambition" in Japanese version), There is a short paragraph describing
Iserlohn's size and armor. It roughly translates to: "diameter sixty
kilometers; the interior could be separated into several thousand levels;
the surface had special treatments to resemble a mirror surface, able to
withstand energy beam attacks; it was made of compound armor of extremely
hardened steel, crystalized fibers, and special ceramics, four levels in
total, almost impregnable." I guess this does not exactly mean liquid metal??
As some additional information: the space dock could accomodate
twenty thousand ships, the refit factories could repair four hundred
battleships, the hospital had two hundred thousand beds, the ammunition
factories could produce seven thousand five hundred laser fusion missiles,
all at the same time.