[Technology] Preparation of Magnesium Alloy Before Melting
Preparation of the magnesium alloy before melting Since the molten metal comes into contact with or mixes with water, the water instantly becomes steam regardless of the metal, causing a blowout explosion. Magnesium not only reacts with water, but also generates heat and nitrogen. According to the amount of water, the reaction can also cause hydrogen to explode, leading to serious disasters. Therefore, care must be taken to dry the magnesium ingot and pay attention to articles that may come into contact with the molten magnesium, and maintain the operating point. dry. For rusted magnesium ingots, recycled materials, etc. should be grit blasted, if there is serious flux inclusions and residual burning marks on the surface of the returned material, it must be remelted.
The preheating temperature of the magnesium alloy is 150-3500C. The boiling point of water is 100Ct, so the minimum is 1500C. As the temperature rises, the chemical properties of magnesium alloys become more and more active, and chemical changes easily occur. When the magnesium alloy is heated to 350°C, protective gas protection should be added.
Magnesium alloy furnaces: Magnesium alloys can be melted in a furnace heated with electric heating wire, oil or gas. Due to low gas prices, the United States generally uses gas furnaces. However, the United States is gradually using electric stoves because the scales on the gas furnace will cause galling, as well as the disadvantages of water vapor formation. In Europe, electric stoves dominate. Electric stoves are simple to operate and can precisely control the temperature, and thermocouples are installed inside the furnace and near the heating elements to prevent overheating.
All kinds of covering flux and refining flux should be dried at 120-150°C for more than 1h before use, washing flux to wash the bittern or Rj-1 flux) to be heated to 780-8000C, and the amount of flux should not be less than 80% of the volume capacity of the crucible. And new flux is added according to the consumption of flux. After the continuous smelting of 20 furnace alloys (up to 30 furnaces at the most), the flux in the crucible should be completely renewed. Magnesite and other metamorphic agents should be broken to about 10mm before use, and baked at 120-1500C temperature 11: above. Before the use of flame retardants such as sulfur powder and boric acid, the agglomerates should be crushed, sieved through a No. 40 sieve, and then stored in a closed container for use.
Clean the slag, oxides, and other contaminants on the surface of the tool with wire brushes, shovels, or hammers. The bell jar, stirring spoon, and ladle must be washed clean and preheated to bright red before use. Specimens, fracture specimens, ingot molds should be preheated and sprayed before use.
Finally, check whether there is any crack in the weld bead. If there is leakage, it should be scrapped.
For the new crucible, the flux should be used after cleaning and cleaning; for the old crucible, the wall thickness of the crucible should be measured with a gauge that specifically inspects the thickness, and the available local minimum wall thickness is not less than 6 mm.
Lens,Fused Quartz Cuvette,Optical Elements &Components,Quartz Convex Lens
Yixing Jingke Optical Instruments Co.,Ltd. , https://www.jkgxcn.com