Application direction of thermal spraying technology in metallurgical industry[1]

       

One. Production characteristics of metallurgical industry

  The metallurgical industry produces from ore to metal materials, during which it goes through multiple production links such as mining, transportation, storage, crushing, classification, sorting, liquid-solid separation, agglomeration, sintering, smelting, casting, and refining. The main equipment of each link is under extremely harsh working conditions such as high wear, high load, high temperature and corrosion. These factors lead to the failure of production equipment, making the metallurgical industry a major energy consumer in the national economy. Faced with this situation, in order to maintain production, a large amount of spare parts must be consumed every year, some of which need to be imported. A large steel company has to pay hundreds of millions of yuan each year. On the other hand, modern metallurgical production is a highly continuous process. Even if the equipment in each part of the production link fails prematurely, it will stop or reduce production and bring huge economic losses. For example, a blast furnace slag hole of a steel company in my country has a very short working life due to the erosion of high-temperature melt. Every time it is replaced, the blast furnace needs to be closed for air decompression, three batches of charge are added, and 60t less iron is born.

  The continuous casting roller table of the converter continuous casting production line of this enterprise has a life span of only 4,000 furnaces (200,000 tons), while the same type of continuous casting roller table in Japan can reach 15,000 furnaces, which is almost four times as high.

Two. Anti-high temperature oxidation coating

  1. Function. These coatings are used to improve the high temperature performance of the substrate (equipment or facility) material (higher temperature can reach 1150°C), so that it can withstand the high temperature chemical or physical dissolution process and the erosion process of mechanical damage, or both.

  2. The requirement of anti-high temperature oxidation coating. In order to prevent the substrate from damage caused by high-temperature oxidation, these coatings must: prevent the diffusion of oxygen in the atmosphere; prevent the coating itself from rapidly diffusing to the substrate; have a melting point higher than the operating temperature; and have a lower vapor pressure at the operating temperature .

  3. The recommended spraying materials are nickel-chromium alloy, nickel-chromium aluminum alloy, and sprayed aluminum for sealing and hot infiltration.

  4. The recommended spraying methods are plasma spraying, high-speed flame spraying, and combustion flame spraying.

  5. Application examples include heating furnaces, soaking furnaces, heat treatment furnaces, sintering furnaces, hot blast furnaces, regenerative furnaces and regenerator walls, the surface of metal grate; annealing pan, annealing hood, heat treatment fixture, outer surface of rotary kiln , High temperature valves, sliding gates, flues and chimneys, etc. Polysilicon furnace, sintered metal forming, exhaust muffler, blast furnace tuyere, air supply system, sintering equipment, blast system, clean air system, smoke exhaust system, annealing furnace roll, Franklin furnace, hot metal impregnation heater, titanium Bars, forging tools, heating mantle, coke oven sealing device, blast cooling system, converter oxygen supply system, coke oven tuyere, continuous casting roll and cooling sand mold, etc.