alumina is aluminum oxide. Not to familiar with its properties.

Im a bit of a fan of Joe Buff's books, involving the USS Challenger, an ultra-high tech SSN, (basically a seawolf with VLS and a ASDS hangar). This sub is unusual in the face that its made out of something called 'alumina', described as a ceramic composite. The hull of this boat is supposed to enable it to dive to, and engage in combat at, depths of approaching 4000m. It is supposed to give this sub, and other ceramic-hulled SSN's in the books, a huge advantage in undersea combat. Would the expense (And Im assuming it would be very expensive!) of such a superstrong hull be worth the battlefield advantage? Thoughts..