Main raw materials used for tungsten crucible
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Main raw materials used for tungsten crucible
Tungsten crucible is mainly made of tungsten powder raw material.
Tungsten plate rolling can be divided into hot rolling, warm rolling and cold rolling. Due to the large deformation resistance of tungsten, ordinary rollers cannot fully meet the requirements of tungsten sheet rolling, and special material rollers should be used. During rolling, the rollers must be preheated. Depending on the different rolling conditions, the preheating temperature is 100-350℃. The relative density of the billet (the ratio of actual density to theoretical density) is greater than 90% before it can be processed. The processing performance is good when the billet density is 92-94%. The blanking temperature of hot rolling is between 1350 and 1500℃. If the deformation process parameters of blanking are not properly selected, the billet will be delaminated. The starting temperature of warm rolling is 1200℃, and the thickness of the hot-rolled plate with a thickness of 8 mm can reach 0.5 mm after warm rolling. Due to the large deformation resistance of tungsten plate, the roller body bends and deforms during rolling, making the thickness of the plate uneven along the width direction. When changing rollers or rolling mills, the plate may crack due to uneven deformation of various parts. The plastic-brittle transition temperature of the 0.5 mm thick sheet is still at room temperature or above room temperature, and the sheet is brittle. The sheet should be rolled into 0.2 mm at 200-500 ° C. In the later stage of rolling, the tungsten sheet is thin and long. In order to ensure uniform heating of the sheet, graphite or molybdenum disulfide is often coated, which is not only conducive to the heating of the sheet, but also has a lubricating effect during processing.
