What is tungsten crucible? It is made by turning and welding with tungsten rod, and produced from pure tungsten plate, tungsten sheet and pure tungsten rod according to relevant technology, many types of preparation methods are available. It has wide application in rare earth smelting, quartz glass, crystal growth and other industries, and plays an important role in modern industry.
Six main preparation methods of tungsten crucible are available:
1.0 Isostatic pressing sintering method
2.0 Forging method
3.0 Chemical vapor deposition method
4.0 Plasma spray forming method
5.0 Spinning method
6.0 Riveting and welding forming method
Among them there are three types usually used: isostatic pressing sintering, forging, riveting and welding forming method. Most products are made by them. High-purity, high density and large-size products can be produced by using chemical vapor deposition method, predictably its development will play an important role in future.
As the isostatic pressing sintering method is one of the most important preparation technologies and the most common production method for the production of this crucible, the production level of large-size crucible in China ranks top in the world. In the future, the emphasis will be laid on continuous improving the process level of cold isostatic pressing and sintering technology, the following is preparation detail:
The isostatic pressing sintering method mainly has six working procedures including raw material batch, powder loading, isostatic pressing, high temperature sintering, turning and finished product inspection. There are the following steps: assemble the mold based on the required size of the die, put the tungsten powder raw materials into the mold and seal according to the requirements of the national standard, put them into the cold isostatic pressing machine to press with the forming pressure of generally 180~250 MPa, and then put the compact into the high temperature induction sintering furnace for sintering, the temperature rising rate is 80~150℃/h, the maximum temperature is 2200~2400℃, and the high temperature holding time is 4~8h. The sintered mass is processed in accordance with the requirements of the finished products, then the last is to inspect the appearance, size and density of the finished products.
