Electronic and electrical
Molybdenum has good conductivity and high temperature performance, especially close to the thermal expansion coefficient of glass. It is widely used in manufacturing the core wire, lead wire, hook, bracket, side bar and other parts of spiral filament in bulb, and as grid and anode support material in electron tube. Molybdenum is used as metal oxide semiconductor gate in VLSI, and bimetallic effect can be eliminated by mounting integrated circuit on molybdenum. The ultra thin seamless molybdenum tube (about 15 μm) can be used as anode support for the picture tube of high definition TV. The number of image scanning lines of this kind of TV is 1125, which is two times higher than that of ordinary TV. The molybdenum wafer can also be used as the base plate and heat sink of power transistor heat shield and silicon rectifier.
In modern electronic industry, in addition to pure molybdenum, MoRe alloy can be used as structural material of electron tube and special light bulb. Mo-50Re and TZM alloy can also be used as thermionic cathode structural element in high power microwave tube and millimeter wave tube. Its working temperature can reach 1200 ℃ and current density can reach 10 a / cm2. In recent years, some people have developed to add Si, K and C to improve the recrystallization temperature and produce "high temperature molybdenum wire". Adding rare earth elements such as yttrium, cerium and lanthanum to molybdenum oxide production process can effectively improve recrystallization temperature and overcome high temperature embrittlement. The molybdenum wire containing 0.1-0.3% zirconium and 0.1% scandium is nitrided at 1200 ℃ to disperse scandium into the whole alloy. The tensile strength of the molybdenum wire can reach 1400 million Pascal at 20 ℃.
With the rapid development of die and mold industry, EDM technology has been widely used. Molybdenum wire is an ideal electrode wire for WEDM, which can cut all kinds of steel and cemented carbide, and process extremely complex parts. Its EDM is stable and can effectively improve the accuracy of the die.
The development of bulb manufacturing industry and the rise of mold manufacturing industry make the production and consumption of molybdenum wire advance by leaps and bounds. According to the statistics of China Lighting Association, in 2001, the national production of molybdenum wire reached 3.15 billion meters, the actual output is estimated to reach 4 billion meters, and the consumption of nearly 800 tons of molybdenum bars is very considerable. Among them, the output of molybdenum wire for WEDM is more than 2 billion meters, accounting for more than half of the total amount of molybdenum wire.
Tungsten copper pseudoalloy is widely used as tool electrode in EDM. However, in recent years, molybdenum has been used instead of tungsten as electrode. The results show that the corrosion resistance of tungsten based and molybdenum based electrodes varies with the content of copper (≤ 50% by weight). In the presence of heating pulse and mechanical load pulse, the corrosion resistance mainly depends on the embrittlement process. The ductile brittle transition temperature of molybdenum is lower than that of tungsten, so the brittleness is smaller and the corrosion resistance is stronger. MoCu and MoAg pseudoalloys have good ablation resistance and good conductivity, and can be used as contacts of air switches, high voltage switches and contactors. MoCu composite film can be used as metal core in multilayer circuit board because of its uniform microstructure, good thermal conductivity and conductivity.
Recently, molybdate trioxide has been developed, which can change color under strong light and can be easily reduced. It can be used as optical storage element of electronic computer and copy material for many times.
