what is the strongest ceramic?
porcelain once it is fired, before firing clay is stronger.
in the simplest terms, there are two major families of ceramics -- oxides and carbides. If you mean strongest (rather than hardest), a number of the oxides can form strong structures. Bricks made of kaolin clay are are reasonable example. But, if you mean, hardest, you should consider some of the carbides -- like silicon carbide or tungsten carbide. These are so hard and tough that they are used to cut other ceramics (like the brick we just mentioned).
