Molybdenum crucible is widely used in rare earth, vacuum, chemical industry, laboratory and high temperature processing industry and other fields, but because molybdenum has a high melting point, high strength characteristics, so the processing of molybdenum products has a certain difficulty. The processing method is as follows:
Molybdenum crucible is widely used in rare earth, vacuum, chemical industry, laboratory and high temperature processing industry and other fields, but because molybdenum has a high melting point, high strength characteristics, so the processing of molybdenum products has a certain difficulty. The processing method is as follows:
1. Plasma spraying method
The powder is prepared by ball milling and spray drying, and then the powder is processed into a molybdenum deposit layer with a predetermined thickness by plasma spraying, and then the deposit layer is treated by hot isostatic pressing. The final molybdenum crucible produced has good dimensional stability, strong mechanical properties, but high raw material consumption and high price.
2. Casting method
Molybdenum is first made into electrodes, and then melted into a liquid in a vacuum furnace and molded into an injection model. The process can complete the preparation of various sizes of molybdenum crucible, save raw materials, but the preparation process is complex, need to make a large number of molds, and molybdenum melting point is high, need to consume a lot of energy to melt it.
3. Stamping method
Using the plasticity of molybdenum slab under heating condition, the crucible was prepared by stamping process. Its material utilization rate can reach 75%. However, it is very suitable for making crucible with large wall thickness, and it is difficult to process crucible with large size and thin wall.
4. Welding method
According to the size of the required crucible, a suitable molybdenum sheet was obtained, and the sheet was heated in the hydrogen furnace, and the copper bottom was stitched with the welding cylinder of the vacuum welding box. The process has the advantages of low cost, simple production process and suitable dimensional accuracy. However, the welding crucible is easy to crack at the weld during use, which will reduce the service life of the crucible.
5. Sintering method
Molybdenum and its alloy powder are formed by isostatic pressing, turning and shaping, and then sintering by high temperature furnace. The method has high utilization rate of raw materials, high dimensional precision and stable mechanical properties of the produced crucible. However, the crucible is easy to deform in sintering molding, and the larger the crucible size and the thinner the wall thickness, the more likely it is to deform. Moreover, the existence of pores in the sintering process will affect the strength and service life of molybdenum crucible.
