High Velocity Oxy-fuel Spraying

High Velocity Oxy-Fuel (HVOF) Spraying is widely used now for many industrial applications and is probably the best among the thermal spray techniques for some specific needs, e.g., for deposition of the cement coatings. Both industry and research laboratories have a need to improve their understanding of the HVOF spray processing in order to develop the optimum conditions and effective control of HVOF spraying which enables production of the quality coatings. Addressing this need is the main objective of this book. HVOF spraying has proved to be technically feasible and has become indispensable in many areas of high technology, such as aerospace industry, automobile manufacturing, powder production, electronics, chemical industry, pulp and paper industry, machinery manufacturing, petroleum and petrochemical industry, biomedical applications, etc. World industry faces serious new challenges. A new emphasis on the conservaion of materials will bring higher demand for HVOF sprayed coatings to increase wear and corrosion characteristics of many different substrates. It is expected that the newly developed multicomponent coatings (metastable, mixed, multilayered or graded with carbides, oxides, nitrides and cermets), special coating structures (nanocrystalline and amorphous), superhard deposits and polymer coatings will soon become standard items in the list of engineering materials. This book covers the main aspects relating to fundamentals and applications of HVOF spraying. The first chapter deals with the basic methods of characterisation of materials structure, which include optical microscopy, transmission electron microscopy and scanning electron microscopy. There are many references in literature relating to the standard methods of characterisation, however, we guess that a very simple general view on these issues would help the readers to refresh their memories. The issues related to powders for HVOF spraying (powder materials and methods of powder manufacturing and evaluation) are described in the second chapter. The third chapter is devoted to the methods of coating evaluation and includes valuation of the coating structure and properties.