A ceramic paintball barrel tends to be a misconception within paintball. When someone talks about a ceramic paintball barrel they are referring to an aluminum barrel with a ceramic coating on the inside.
The main benefit of having a "ceramic paintball barrel" is for any player that breaks a paintball. The broken paint from the ball does not stick well to the ceramic which allows you to shoot the majority of broken paint out of your gun without having to squeegee your barrel.
There are no fully ceramic paintball barrels available for purchase at this time.