Abstract: An article has a cavity defined by an inner surface, the cavity having a size such that a largest sphere placeable in the cavity has a diameter of less than 7 cm and a smallest sphere placeable in the cavity has a diameter of 0.5 mm; and a hard coating on the inner surface, the hard coating having a hardness between 18 to 100 GPa, the hard coating distributed on the inner surface such that a ratio of a coating thickness at a first region of the hard coating to that at a second region of the hard coating ranges from 0.75 to 1.33.

Abstract: An article has a cavity defined by an inner surface, the cavity having a size such that a largest sphere placeable in the cavity has a diameter of less than 7 cm and a smallest sphere placeable in the cavity has a diameter of 0.5 mm; and a hard coating on the inner surface, the hard coating having a hardness between 18 to 100 GPa, the hard coating distributed on the inner surface such that a ratio of a coating thickness at a first region of the hard coating to that at a second region of the hard coating ranges from 0.75 to 1.33.

Abstract: A thermal barrier coating includes a microstructure and an composition including: at least one ceramic based compound comprising at least one oxide of a material selected from the group consisting of lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, indium, scandium, yttrium, zirconium, hafnium, titanium, and combinations thereof. The coating includes a nano-structure having a porosity of at most 50% by volume of the coating, and the coating comprises nano-structured inclusions.

Abstract: A gas turbine engine airfoil is made from separate cast sections having different cast alloy structures. The cast alloy structures are selected on the basis of the local operating conditions of each section. Friction welding can be used to join the sections together.