Nano Crystalline Ceramic and Ceramic Coatings Made by Conventional and Solution Plasma Spray

Nanostructured ceramic coatings produced by plasma spray processes are being developed for a wide variety of applications that require resistance to wear, erosion, cracking and spallation [1]. In addition the process is being developed to make near net shaped ceramic performs by dissolution of the substrate after spraying. Attractive properties associated with a nanostructure (in general referring to grain size smaller than 100 nm) have been documented for bulk materials [1–8]. It is anticipated that, if properly deposited, nanostructured ceramic coatings could also provide improved properties for variety of applications, including wear resistant [9, 10] and thermal barrier coatings [11, 12]. Thermal spray techniques are often used to deposit thick oxide coatings and experimental examination of phase constituents, microstructures and mechanical properties with respect to processing conditions have been extensively carried out and reviewed [13–19]. This is one of the first papers that deals with similar studies for nanostructured coatings. In this paper three different applications are discussed. Conventional air plasma spray of nano crystalline alumina-titania ware coatings for ship applications and then liquid precursor spray of nano crystalline thermal barrier coatings for turbine applications finally a brief mention of recent progress in spraying dense materials for use a stand alone ceramics will be presented.