Application direction of thermal spraying technology in metallurgical industry[2]

       

Three. Corrosive gas coating

  1. Function: These coatings must protect the substrate material exposed to high-temperature corrosive gas. Due to the simultaneous existence of oxidation and chemical reaction, it is necessary to prevent the product of the coating and gas reaction from damaging the substrate.

  2. Requirements for the corrosion-resistant gas coating: it can withstand high-temperature corrosive gas; it can withstand periodic thermal shock and overheating; it must match the thermal expansion coefficient of the substrate.

  3. The recommended spraying material is nickel-chromium alloy (except for sulfur-containing media), sprayed aluminum for sealing and hot infiltration.

  4. The recommended spraying methods are plasma spraying and combustion flame spraying.

  5. Application examples include the inner surface of rotary kiln, brazing fixture, carbonization box, exhaust fan blade, cyanidation crucible, gas flue system, power plant boiler return pipe, coke oven tube, converter boiler, etc.

Four. thermal barrier coating

  1. Function. These coatings have low thermal conductivity and act as a thermal barrier to reduce the degree of heating of the base metal.

  2. Requirements for thermal barrier coatings. These coatings should meet: must be resistant to oxidation at working temperature; have good thermal shock resistance; be as close as possible to the thermal expansion coefficient of the substrate; and have low thermal conductivity.

  3. The recommended spray materials are chromium oxide, aluminum oxide and magnesium chromate.

  4. The recommended spraying method is plasma spraying.

  5. Application examples include high temperature furnace induction coils, brazing and heat treatment fixtures, torch thermal barriers, heating hoods, pyrometer casings, and U-shaped grooves in cast iron plants.

Five. anti-melting metal coating

  1. Function: These coatings can withstand the action of molten metals such as zinc, aluminum, steel, iron and copper.

  2. Resistance to molten metal coating requirements. These coatings should meet: can withstand the corrosive action of slag and flux and the corrosion of metal vapor and oxygen near the melt level; prevent the coating and the melt from forming low-melting alloys; and can withstand thermal fatigue and thermal shock.

  3. The recommended spraying materials are aluminum oxide, magnesium chromate, white tungsten and platinum.

  4. The recommended spraying methods are plasma spraying and combustion flame spraying.

  5. Application examples include galvanizing tanks, casting tanks, molds, tuyere, zinc distillation tanks, condenser tubes, zinc alloy melting furnaces, galvanizing dip tanks, blast furnace slag ports, aluminum casting molds, copper casting molds, continuous casting machine molds, Sand casting mold, plate crystallizer, zinc smelting stirring device, crystallizer guard plate, oxygen pipe nozzle, converter oxygen lance, ladle nozzle, metal melt temperature measuring head and graphite electrode.

Six. wear-resistant coating

  In the metallurgical industry, the major factor in the failure of various mechanical equipment is wear. The more important function of thermal spraying is to provide wear-resistant coatings to effectively protect a large amount of engineering wear. The application range of this type of coating is wider than other types. The wear mechanism is complex, there are many types, and the metallurgical production conditions are different, so the functions and requirements of this type of coating are not the same.