Lanthanum molybdenum oxide foil strip and its manufacturing method
Due to the high temperature strength, good electrical and thermal conductivity, low expansion coefficient and easy processing of refractory metal molybdenum, molybdenum wire has been widely used in automobile halogen tungsten lamp, high pressure sodium lamp, lighting halogen tungsten lamp and special electric light source devices to manufacture the hooks, core wires, lead wires, plastic support and other parts required by them. However, when pure molybdenum foil strip with thickness between 0.02 ~ 0.06mm is used as the gas sealing material between molybdenum rod and quartz glass in special light bulbs and special electric light source devices, the sealing temperature is as high as 1700 ~ 1800℃, while the recrystallization temperature of pure molybdenum is only 1000 ~ 1200℃, so brittle and fracture often appear. Its high temperature strength is also low and easy to deformation. This is because the recrystallized grains grow up and form equiaxed grain structure after recrystallization. At present, molybdenum foil strip is generally replaced by molybdenum foil strip processed by high temperature molybdenum wire doped with Al2O3, SiO2 and K2O. However, its processing performance is poor, and it needs to be processed by hot rolling and multiple intermediate annealing above 800℃. As a result, the process is complicated and prone to crack and delamination, so the yield is low and the price is high. Lanthanum molybdenum alloys foil strip can solve this problem well.
The characteristics of lanthanum molybdenum alloy foil strip are that it also contains La2O3, which is 0.2 ~ 0.6% by weight of molybdenum. It is successively made from the following steps: (1) La2O3-Mo wire is made by traditional powder metallurgy or plastic processing, where the weight ratio of La2O3 to molybdenum is 0.2 ~ 0.6%; (2) The graphite milk or oxide skin on the surface of La2O3-Mo wire is removed by well-known electrolytic or chemical cleaning method, and the graphite milk or oxide skin is pre-annealed in a hydrogen furnace with a temperature of 1300 ~ 1400℃; (3) When La2O3-Mo wire is cold rolled at room temperature, the first deformation is 20 ~ 30%; (4) When the total deformation reaches 60 ~ 65%, the rolling is interrupted and the first intermediate annealing is carried out between 900 ~ 1100℃; (5) The La2O3-Mo strip after the first intermediate annealing is fine rolled at room temperature. When the total deformation reaches 70 ~ 80%, the strip can be rolled directly to lanthanum molybdenum oxide foil strip after the second intermediate annealing at 800±10℃.
