Abstract: Materials and associated processes for making the materials. For example the material may include alpha alumina crystalline whiskers. The process may include conducting the process as hydrothermal, and producing the whiskers to have a length to diameter aspect ratio of at least two.

Abstract: A hydrothermal process for making Alpha Alumina (?-Al2O3) crystalline nano-sized powders in the form of at least one of nano-sheets and nano-fibers, the process includes making the Alpha Alumina with an aspect ratio of diameter to thickness ratio of at least two, and with at least one dimension of diameter or thickness being less than 100 nm. A composition in accordance with the process. A porous ceramic that includes the composition.

Abstract: A process to deposit an Alpha Alumina (?-Al2O3) crystalline coating on a substrate surface, wherein the process includes hydrothermal synthesis of the ?-Al2O3 crystalline coating.

Abstract: A process of making a crystalline powder and the powder. The process includes providing at least a precursor material; hydrothermal synthesis to create a predetermined amount of boehmite as an intermediate product from the at least precursor material; hydrothermal synthesis to convert at least a portion of the boehmite to alpha alumina, wherein any remaining, un-converted boehmite is attached to alpha alumina. The process may be part of a process to make and extrudate and the extrudate. The composition and extrudate may include alpha alumina crystals with surface adhesions of boehmite. An apparatus for hydrothermal synthesis of high purity alpha alumina powder, the apparatus including an autoclave with titanium liners, a pressure relief system and a heat exchanger.