In the previous article, we discussed how to prolong the life of molybdenum crucible and continue to share this theme today.
Performance ratio of pure molybdenum material and F4200J material,Compared to the table
material quality |
conditions
| tensile strength
| σb(900℃)/σb(room temperature)%
| hardness
| Number of grains/mm2
| ||
σbMPa | σsMPa | HBS | HVσ0.2 | ||||
M molybdenum
| room temperature
| 360 | 295 | 23.2 | 146 | 188 | 768 |
900℃ | 100 | 65 | |||||
F4200J | room temperature
| 360 | 345 | 59.2 | 156 | 227 | 1024 |
900℃ | 215 | 96 |
Service life of molybdenum crucible ——to improve tensile strength
As shown in Table 1, although the strength of the two materials at room temperature is basically the same, the high temperature strength of F4200J is much better than that of molybdenum, and its retention value is much higher than that of molybdenum. The difference is that molybdenum has obvious yield points, while F4200J does not. Table 1 also shows that the microhardness of F4200J is higher than that of molybdenum and the grain is more refined. The metallographic examination showed that the grain was more uniform before the use of molybdenum material, with a small amount of impurity holes, and the number of grain was 768 /mm2. After 2 months, the grain was seriously grown, and the coarse recrystallized tissue was formed and the grain size was about 1. The grain size of F4200J was fine and uniform before use, and the grain number was 1024 /mm2. After 2 months, the grain grew slightly and the number of grains was 768 /mm2. Therefore, adding cerium oxide 2 can improve Mo structure, grain refinement and high temperature strength.
Service life of molybdenum crucible ——to improve corrosion resistance
The molybdenum crucible is used in the production of molten salt electrolysis. In the high temperature medium, such as hydrochloric acid and hydrofluoric acid, graphite and oxygen, corrosion resistance is poor and the amount of corrosion is large. The smelting products teach and pity M. The addition of cerium oxide can increase the corrosion resistance. The corrosion rate of the three materials is shown in Table 2 (10-9mm/s).
molybdenum
| TM | F4200J |
5.47 | 2.89 | 2.09 |
Table 2 shows that the corrosion rate of TM is close to that of F4200J, and the corrosion rate of F4200J is much lower than that of molybdenum. Therefore, the molybdenum impurities in the rare earth metals such as neodymium and lanthanum are low in the smelting products of F4200J base molybdenum crucible.
Service life of molybdenum crucible - application effect
The service life of molybdenum crucible is prolonged. The service life of F4200J molybdenum alloy crucible is 3 months on average, and is 4~5 times of that of pure crucible.
The molybdenum impurity content in the rare earth metal is reduced. The pure molybdenum crucible is used and the impurity content is >0. 07%. Using F4200J based alloy crucible, molybdenum impurity content dropped to 0. 03%~0.05%
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