ABSTRACT
Thermal spraying (TS) technology at its early developmental stage was used mainly in repairing, restoration works, and for the protection of components against corrosive and erosive wears. TS is a generic term for a family of coating techniques used to deposit metallic, composite, cermet coatings or non-metallic coatings. However, the basic fundamental concept or science behind all thermal spraying processes were not understood clearly up to the early 1980s, when the process handling parameters were fully dependent on the skill, expertise, and experience of the operators. The outcome is unsatisfactory process reliability and poor quality of coatings. But the large-scale acceptance of thermal spraying for industrial sector (mainly in aeronautic and nuclear) had started in the early 1990s, as no feasible solutions were present and the designer, engineers, and researchers were bound to work with these complex processes. In the year 2000, thermal spraying was ranked fourth among the top-quality surface engineering techniques, according to an empirical research conducted by the Institute for Science Transfer by Scientific Education.
Every thermal spraying process has its own characteristic features, area of application, and range of materials that will be sprayed based on its fundamental concepts, and for selecting the appropriate spraying technique, these should be taken into account. In this review article, brief history, characteristic features, area of application, and range of materials that can be sprayed by HVOF, HVAF, plasma, flame, and cold spray will be discussed along with the challenges and future perspectives of thermal spray coating market.
