The lamp with molybdenum strip
Molybdenum strip is widely used in halogen tungsten lamp and high pressure mercury lamp as a non-matching sealing material of quartz glass shell. Metal halide lamp. Although it is only a very small part of the bulb surface, the proportion in the cost is also very small, but it has a great impact on the welding pass rate and lamp life. Many lamp manufacturers use pure molybdenum strip as sealing material of quartz glass shell.
The pure molybdenum strip developed in the early stage is still in use at present because of its low price, simple production technology and its ability to meet the basic requirements of lamp making. The doped molybdenum foil is developed to future improve some properties of molybdenum strip to meet the requirements of lamp making technology, increase the pass rate, prolong the life and reduce the cost. The doped molybdenum strip is divided into silicon doped molybdenum strip (silicon doped concentration is 100 ~ 150ppm Si) doped yttrium molybdenum strip (yttrium concentration is 0.4%~0.6%Y) and lanthanum doped molybdenum strip according to the different trace elements.
The size of the section is mainly determined by the power of the lamp, that is, the current through the molybdenum strip and the mechanical strength required by the welding frame. The shape of the section is very important to ensure good sealing performance with quartz, that is, the gas tightness of the bulb. The edge of the molybdenum strip should be blade shaped, and the thickness of the strip should be less than 5 microns at a width of 10% from the edge. The lamp manufacturer had better check the shape of the section of the molybdenum strip used.
The crystal of molybdenum strip is fibrous and has good mechanical properties because it has been pressed many times in the process. When the temperature increases to a certain value, the molybdenum strip will recrystallize and its fibrous crystal structure will change to granular. The recrystallization temperature of molybdenum strip and the shape and size of grains after recrystallization are related to the kinds of trace elements. From the point of view of lamp making, we hope that the recrystallization temperature is high and the grains after recrystallization are not too large.
