The development direction of thermal spraying technology

       After nearly a century of development, thermal spraying technology has developed from a simple sprayer to a complete industrial system, and has become a key technology in surface engineering and an important part of advanced manufacturing technology. Today, thermal spraying technology has developed into an emerging interdisciplinary discipline integrating machinery, materials, thermal power, high-tech and biological engineering through continuous penetration, crossover and integration between multiple disciplines. The development direction of thermal spraying technology mainly focuses on the discovery of new technologies, the innovation of spraying materials, and the improvement of coating quality control systems, which are embodied in the following aspects.



    (1) New thermal spraying technology and new application fields are emerging. The quality of thermal spray coating depends to a large extent on the speed of molten particles, and increasing the speed of thermal spray jet and spray particles has become a new trend in the development of international thermal spray technology. For example, gas explosion spraying technology, supersonic flame spraying technology, high-speed arc spraying technology, supersonic plasma spraying technology, cold spraying technology, etc., which have appeared successively, all focus on increasing the flying speed of particles, thereby reducing the porosity of the coating and improving the the bond strength of the coating.

    Among them, the supersonic plasma spraying technology has advantages that cannot be replaced by other technologies in the preparation of high-performance ceramic coatings and cermet coatings because the temperature and speed of the plasma jet can be adjusted in a wide range, and the spraying atmosphere is relatively pure.

    (2) The development of thermal spraying technology has promoted the development of new materials. Nano-coating materials (nano zirconia, nano-tungsten carbide, cobalt, etc.), multi-functional composite coating materials (functional gradient thermal barrier coating materials), biological functional coating materials, intermetallic compound materials, microcrystalline and amorphous coatings The production of materials has become the focus of increasing attention today.

    (3) The coating quality control system has been continuously improved. On the premise that the spraying process method is determined, the reproducibility and stability of the spraying process parameters are the basic links to ensure the quality of the coating. Through the online detection of the spraying process, the distribution of the temperature field of the spraying heat source and the flying state of the spraying particles can be monitored in a timely manner. It is suitable for the monitoring of most thermal spraying processes, and provides the basic guarantee for optimizing and stabilizing the preparation process of the coating.

    (4) Basic theoretical research on coating preparation and coating performance testing methods. The basic theoretical research of coating preparation mainly focuses on the basic research of thermal spraying physics (heat source characteristics, heat transfer acceleration behavior of sprayed particles, oxidation behavior of molten particles, etc.), and numerical simulation methods are often used. In addition, neural network, experimental design and other methods are used to determine the relationship between the thermal spray coating preparation parameters and coating properties. Research and establish the mathematical model between the heating condition, motion form and nozzle outlet conditions of spraying particles.

    In terms of the development of coating detection methods, it is mainly to explore how to use optical microscope, electron microscope, X-ray diffractometer, high-speed imaging and other detection technologies to accurately characterize the microstructure characteristics of the coating, and accurately analyze the effect of spraying on the coating structure and coating performance. impact and predict the performance of the coating.