Thermal spray refers to a series of processes in which finely divided and dispersed metallic or non-metallic coating materials are deposited in a molten or semi-molten state onto a surface of a prepared substrate to form a spray-on deposit Floor.
Since the invention of a flame spraying device (ie, thermal spraying) by Dr. Schoop in Switzerland in 1910, thermal spraying technology has been greatly developed, especially since the 1980s, the application of thermal spraying technology has made great Achievements. Compared with a variety of other surface technologies, thermal spraying technology has its own characteristics:
(1) Coatings of various materials, including metals, ceramics, cermets, engineering plastics, glass, wood, cloth, paper, etc., can be prepared on a variety of substrates.
(2) The substrate temperature is low. The substrate temperature is generally between 30 ~ 200oC, small deformation, heat affected zone shallow.
(3) flexible operation. Spraying objects of various sizes and shapes is particularly suitable for large area coatings and working in the field.
(4) Coating thickness range. From tens of microns to a few millimeters of the coating can be prepared, and easy to control, spraying efficiency, low cost. Spraying production efficiency of several kilograms per hour to dozens of kilograms. However, as a surface treatment technology, it also has many shortcomings, mainly reflected in the three aspects of low thermal efficiency, low material utilization, waste and strength of the coating and substrate.
The traditional thermal spraying method according to the different heat sources can be divided into combustion and electric heating method, the former includes flame spraying, explosion spraying, the latter including arc spraying, plasma spraying. In recent years, with the further improvement of coating performance requirements, the majority of scientists through the constant innovation, based on the original development of supersonic flame spraying and supersonic plasma spraying. At the same time, they have also developed laser spraying, reactive thermal spraying and cold spraying processes.