The hottest spraying technology and its applicatio

2022-08-24
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Thermal spraying technology and its application

1 Characteristics and development of surface engineering and thermal spraying technology with excellent service

surface engineering is a systematic engineering that changes the morphology, chemical composition, microstructure and stress state of solid metal surface and non-metal surface through surface coating, surface modification or multiple surface engineering technologies after surface pretreatment, so as to obtain the required surface properties

surface engineering integrates basic theories, technologies and the latest achievements in many fields. Because surface engineering technology makes a layer of coating or film on the surface of the matrix material, or endows the material with many special properties through surface modification, the surface performance of the material is much better than that of the material matrix, which can not only greatly extend the application field of the matrix material, but also solve the problem that the material in many fields cannot meet the environmental requirements. Surface engineering technology plays an irreplaceable role in solving the common problems of resources, energy, environment and so on in human development

because surface engineering technology saves energy and materials, it not only protects the precious resources that human beings rely on for survival, but also plays a very key role in environmental protection. In the 21st century, surface engineering technology will permeate all walks of life, promote social civilization and improve the quality of life

thermal spraying technology is an important branch of surface engineering. It heats some linear and powdery materials to molten or semi molten state through heat sources such as flame, arc or plasma, and sprays the accelerated molten droplets to the substrate at high speed to form a coating. The coating has excellent properties such as wear resistance, corrosion, high temperature and heat insulation, and can repair the size reduction of parts caused by wear, corrosion or machining out of tolerance. The application of thermal spraying technology mainly includes four aspects: long-term corrosion prevention, mechanical repair and advanced manufacturing technology, mold making and repair, and manufacturing special functional coatings. At present, thermal spraying technology has been widely used in almost all industrial fields and household products (such as non stick pots, infrared health heaters, etc.)

at the end of the 20th century, thermal spraying technology developed very rapidly and was rapidly popularized. See Table 1 for the changes of thermal spraying Market from 1980 to 2000. By the end of the 20th century, plasma spraying was still dominant. It is worth noting that high-speed flame spraying (HVOF) is developing rapidly, accounting for 25% of the market, ranking second. Arc spraying technology, due to its good economy and superior coating performance than flame spraying layer, will partially replace flame spraying technology and rise to the third place. Table 1 application proportion of main thermal spraying methods year flame spraying arc spraying plasma spraying high speed flame spraying 1980 39% 6% 55% 2000 12% 15% 48% 25%

2 Application of thermal spraying technology

thermal spraying technology has been widely used, and its main application fields are shown in Table 2. Table 2 main application fields of thermal spraying coatings main types of coating materials types Protective Coatings anodic protective coatings (atmospheric pressure and immersion corrosion resistant coatings) Zn, Al, Zn Al alloys, Al Mg alloys, Al re cathodic protective coatings (chemical corrosion resistant coatings) stainless steel, colored metals and alloys, oxide ceramics, plastics and other polymer materials high temperature oxidation resistant coatings Ni based, Co based alloys, MCrAIY alloys Oxide ceramic reinforced coating wear particle wear and erosion wear carbide + metal, self fusible alloy, oxide ceramic friction and wear resistant coating Mo or mo+ alloy; Non ferrous metals and alloys; Self fluxing alloy; Oxide ceramics in strong corrosive media wear-resistant coating self fusible alloy, high alloy, ceramic special function coating thermal barrier coating oxide ceramics grindable sealing coating metal + non-metallic composite thermal radiation coating oxide composite conductive shielding and anti radiation coating metal solid lubrication coating metal + non-metallic composite superconductivity, electricity resistance The development trend and characteristics of special coatings such as high-temperature plastics in recent years are as follows: (1) large area long-term protection technology has been widely used. For steel structures that have been exposed to the outdoor atmosphere for a long time, aluminum, zinc and their alloy coatings are sprayed to replace the traditional painting method, and cathodic protection is implemented for long-term atmospheric corrosion prevention; (2) Adopt thermal spraying technology to repair and strengthen the localization of large-scale key equipment and imported parts; (3) Application of supersonic flame spraying technology: (4) gas detonation spraying technology has been further applied; (5) High speed and automatic oxyacetylene flame end spraying technology has developed rapidly; (6) Thermal spray technology has been applied in chemical anti-corrosion engineering; (7) Laser remelting technology began to be applied. At present, thermal spraying technology has been widely used in many engineering fields such as military, water conservancy, electric power, chemical industry, construction, environmental protection, biology and so on. Thermal spraying has also been widely used in marine engineering. Thermal spraying has achieved a good long-term protection effect on the hull, deck, barge, flat bottomed ship, tug, etc

3 application of thermal spraying technology in chemical and petroleum industries

corrosion is particularly serious in the chemical industry, which not only causes a large number of material and equipment losses, but also causes the shutdown of enterprises due to corrosion. The losses caused by safety accidents and environmental pollution are more difficult to estimate. Preventing "running, emitting, dripping and leaking" when loading the electronic tensile testing machine is one of the main tasks of equipment management in chemical enterprises. Thermal spraying technology, which integrates a variety of process methods and aims at surface strengthening, can spray all solid engineering materials and has good chemical stability. At present, it has been increasingly used in the chemical industry, and additives containing EVA (ethylene vinyl acetate copolymer) resin are also widely used. Chemical media often contain sulfur and oxygen, such as fuel, alcohol, acetic acid, toluene, glycerol, syrup storage tanks, original shaft sleeve mechanical seals and impellers, which can be solved by thermal spraying. For general weak corrosive media, it can be solved by metal thermal spraying aluminum, zinc, stainless steel and sealing, and for strong acids and alkalis, it can be solved by plastic flame spraying epoxy, polytetrafluoroethylene, etc. The effect is very remarkable. The typical applications of thermal spraying in the chemical industry are as follows: 1. Replace high-grade stainless steel such as stainless steel and titanium alloy with low-grade materials and heating spraying layers. 2. It can be used as anti-corrosion coating for chemical reaction tank, storage tank, mixing device and pipeline. 3. It can be used as a good repair layer for broken porcelain of glass lined equipment

thermal spraying has also been widely used in the petroleum industry. Thermal spraying has been successfully used in the repair and protection of oil exploration, production and other equipment. Thermal spraying coating has been successfully used for long-term corrosion protection of oil steel pipes and offshore platforms. The arc spraying technology introduced by an engineering installation company of a downhole operation company has better solved the problem of metal corrosion prevention and filled the blank of metal corrosion prevention in oil field. At present, the global output of the engineering installation company has exceeded 1.5 million tons. This technology has been applied to wire rods, plates, profiles and metal equipment, and the anti-corrosion capacity of the products after spraying has been increased by more than 2 times. (end)

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