Overview of Thermal Spray Technology

       It is well known that, except for a few precious metals, metal materials will suffer from chemical and electrochemical reactions with the surrounding medium and suffer from corrosion. In addition, the wear of metal surfaces caused by various mechanical actions is also extremely serious. A large number of metal components fail due to corrosion and wear, resulting in great waste and loss. According to the statistics of some industrially developed countries, the annual loss of steel due to corrosion and wear accounts for about 10% of the total output of steel, and the amount of loss accounts for about 2-4% of the total output value of the national economy. The value is even more astonishing if the stoppages and production stoppages caused by metal corrosion and wear and the corresponding losses caused by work-related injuries, fires, explosions, etc. are included. Therefore, the development of metal surface protection and strengthening technology is a major issue that countries are generally concerned about.



With the development of science and modern industry, various industrial sectors increasingly require mechanical equipment to be able to operate under high parameters (high temperature, high pressure, high speed and high automation) and harsh working conditions (such as severe wear and corrosion) Long-term stable operation. Therefore, higher requirements are also placed on the performance of materials. It is obviously uneconomical and sometimes even impossible to use high-performance advanced materials to manufacture integral equipment and parts to obtain surface protection and strengthening effects. Therefore, the research and development of material surface treatment technology has great technical and economic significance. The surface treatment technology has also been rapidly developed and improved under the impetus of this demand.



Thermal spraying technology is one of the surface protection and strengthening technologies and an important discipline in surface engineering. The so-called thermal spraying is to use a certain heat source, such as electric arc, plasma arc, combustion flame, etc., to heat powder or filamentary metal and non-metallic coating materials to a molten or semi-molten state, and then use the power of the flame itself or external heating. The high-speed airflow is atomized and sprayed onto the surface of the pretreated base material at a certain speed, and combined with the base material to form a surface covering coating with various functions.



In recent years, the important role played by thermal spraying technology in national economic construction has attracted more and more attention. As an important part of surface technology, it has made remarkable achievements in the key promotion and application of my country's national "Sixth Five-Year Plan" to "Ninth Five-Year Plan" for four consecutive five-year plans, and obtained significant economic benefits. At present, both in equipment, materials, technology, scientific research and other aspects are developing and improving rapidly. From the special reports of domestic and foreign experts and the papers read at the "15th National Thermal Spray Technology Experience Exchange Conference" held in Ningbo in October 2006, it can be seen that the general situation and characteristics of the recent development of thermal spray technology in my country are: The equipment (spray gun) is developing towards high energy and high speed; the material is developing towards serialization, standardization and commercialization to ensure the needs of multi-functional and high-quality coatings; the technology is developing towards mechanization and automation.