A thermal spray coatings have been widely applied to parts in different industries, including metallurgy and steelmaking, automotives, chemical processing, oil and gas exploration, paper and pulp, textiles, electric/electronic, and aeronautic and aerospace industries to effectively improve their performance and reliability through enhancing wear resistance, corrosion resistance, high-temperature resistance, thermal barrier effect, and so on. Among those up to over 30 industries, the aircraft gas turbine industry is regarded as the most lucrative market for thermal spray. As shown in Figure 6.1 (Walser 2004), thermal spray coatings have been applied to whole aircraft from the fan to the turbine section. It was estimated that some engines have close to 5500 parts which are thermal spray coated (Gorham 1990). The need for thermal spray coatings is still increasing due to the expanding applications, particularly for ceramic coatings for thermal barrier coatings (TBCs) and for clearance control.