Molybdenum foil analysis for lamps
Think about it, molybdenum foil of the same width and different thickness, if 0.1mm thickness can withstand 10 N force, 0.2mm thickness should withstand 20 N force. From this point on, the thickness of the molybdenum foil should. The thicker the better. However, the thicker the molybdenum foil is, the higher the probability that there is no crushing and air gap in the sealing part, so it is necessary to find and determine the optimal point of thickness. The actual situation is also the same. If a thinner molybdenum foil is used, for example, the thickness of the molybdenum foil is 0.03mm, the cracking and crushing of the molybdenum foil will reach about 80%. If the thickness of molybdenum foil is thickened, and the thickness is 0.07~0.08 mm, the tensile mechanical property will be greatly improved, and the cracking and crushing of molybdenum foil will be basically 0.
Molybdenum foil oxidizes easily in air and forms a "cold" oxide layer. Molybdenum foil with oxide layer, what kind of sealing effect will it have? It can be understood through the test that the deplated I batch of molybdenum foil is placed for 1 year, and then taken out. It is found that the surface of the deplated batch of molybdenum foil has no outdated metallic luster, and there is a dull "cold" oxide layer.
During the test, the molybdenum foils with oxidized layer were divided into two groups: the first group was first treated with hydrogen burning, and then mounted and sealed into lamps; The other group is not processed by hydrogen burning, and is directly mounted and sealed into lamps. The results showed that the degree of cracking and crushing in the group without hydrogen burning was about 17% higher than that in the group after hydrogen burning.
It can be inferred that the oxidizing layer on the surface of molybdenum foil belongs to the weak oxidation state and quickly forms the strong oxidation condition when it meets high temperature. The mechanical properties of molybdenum foils in strong oxidation state are greatly changed and their toughness is decreased, which is one of the main causes of molybdenum cracking and crushing.
So, the group 1 that has been burned hydrogen in the above test, after all, has been placed for 1 year before processing, and peroxide has occurred, then compared with the molybdenum foil that is immediately sealed after deplating, its qualified rate will be what? The same batch of deplated molybdenum foils at that time were immediately mounted and then pressed and sealed into lamps to test the qualified rate of cracking and crushing degree (through the production qualified rate report), and it was found that there was little difference between them.
Vacuum cabinet can be used to delay or reduce the "cold state" oxidation degree of molybdenum foil. There are two ways to use vacuum cabinet: the first is to pump vacuum into the cabinet directly after the device is placed into the cabinet to reduce the damage of oxygen or water; The second is to put the device into the cabinet after the first vacuum, and then filled with inert gas to protect. The second method is more effective, but also expensive. To eliminate the "cold state" oxidation layer of molybdenum foil, only re-burning hydrogen reduction method is adopted at present. But this method is best used only once or twice, such as multiple use, will also cause the toughness of molybdenum foil decline.
