Something About Refractory Metal In Powder Metallurgy-pretty rhythm

Reference-and-Education Refractory metals (mainly tungsten, molybdenum, tantalum, niobium) and alloys are produced in powder metallurgy method. And the main process of the refractory metals, especially tungsten, molybdenum materials, is powder metallurgy process. 1903 German Bolton (W.vonBolton) obtained tantalum wire, as the incandescent filament. 1909 U.S. Kuli Ji (WDCoolidge) replaced with a tantalum powder obtained tungsten wire for incandescent lamps. Made in 1910 with the same process molybdenum wire, which opened up the tungsten, molybdenum powder metallurgy of the road. Early tungsten, molybdenum and other refractory metal products are the small size of the rod, wire, foil and strip, mainly for light bulbs and electronics industries. Since the 1940s, the aviation, aerospace and nuclear sectors such as high-performance, large-sized refractory metal material needs, the development of vacuum smelting technology for the development of large-scale and high-temperature isostatic press sintering furnace (2400), manganese powder in order to advance powder metallurgy process development. China in the mid-1950s, industrial production, electric light and electronics required tungsten, molybdenum material; the late 1950s early 1960s and developed into a tungsten-rhenium alloy wire, heavy alloy and tungsten-based contact materials; built in the mid-1960s, large cold isostatic press and high-temperature sintering furnace, the development and production of a series of large and high-performance tungsten, molybdenum material and products. .pared with the melting process, refractory metal powder metallurgy process has the advantage: the alloy can produce many kinds, made of alloy .position and uniform grain size small, short process, low energy consumption, high material collected. However, this method of production of material purity as the production of high vacuum smelting (interstitial elements such as carbon, oxygen, nitrogen content), thus affecting the performance of certain products. Preparation process of tungsten powder, molybdenum powder of Preparation process, including the extraction, boron powder pressing, sintering and machining processes. Industrial use of hydrogen reduction of tungsten trioxide and molybdenum trioxide Preparation of tungsten powder and molybdenum powder. Reduction process is mainly based on the production system of powder required powder size and size distribution may be. The higher reduction temperature, from tungsten powder and molybdenum powder particle size the more crude to take fine-grained powder is generally used to restore the second: the first is at a lower temperature (W550 ~ 800, Mo450 ~ 650) under the three oxide reduced to dioxide, the second and then at higher temperatures (W750 ~ 900, Mo900 ~ 950) under the two oxide reduction to metal powder. Preparation of coarse powder using a restore, that is, the higher temperatures in the three direct reduction of metal oxide powder, or to improve the second reduction temperature obtained coarse particles of metal powder. In recent years the development of blue tungsten oxide reduction process from the system tungsten powder. Tungsten powder and molybdenum powder particle size of its repressive, sintering, and final product performance has a significant impact. Preparation of the powder .pact tungsten, molybdenum products, silicon powder powder metallurgy industry, there are two ways: the tungsten or molybdenum powder with a powder made of billet metal molding, sintering and then melting down, and then swaging, and then forging rods, drawing or rolled into a sheet; can be used for making small size of the wire, foil, strip. the tungsten powder and molybdenum powder formed by cold isostatic pressing and then sintered into billets or finished products, this process can produce large-sized and shaped parts; such as crucibles, molds, head and all kinds of pipes and so on. Refractory metal powder refractory metal materials in addition to the electronics industry and a large number of applications of industrial light bulb filament, ribbons, tubes, sheets and bars, but there is a large amount of industrial use of molybdenum glass electrode, nickel powder seamless steel pipe with perforation molybdenum titanium zirconium alloy head, heavy alloy, tungsten copper, tungsten copper, nickel, tungsten-nickel-iron, tungsten alloy silver fake. The following sections describe these types of materials: fused glass with molybdenum electrodes. Molybdenum has excellent resistance to molten glass corrosion, use it instead of molten glass platinum electrode, using a good effect, saving precious metals platinum, greatly reducing production costs. The use of molybdenum metal with wood accounts for more than 60%. Pure molybdenum powder electrode is formed by cold isostatic pressing, sintering temperature (2000 ~ 2200) and then from 1200 to 1250 under the hot-rolled or forging, made of plate or rod electrodes. heat-resistant steel seamless steel tubes perforated titanium zirconium alloy with molybdenum head. Now produces two powder metallurgy molybdenum alloy head: the head and sintered sintering – change shape head. Head of the fine grain powder metallurgy, plastic good, work is not easy to crack, long life, wear a tube of good quality it is the powder of molybdenum powder and TiH, ZrH powder mixing, cold isostatic molding, high temperature (about 2000) sintering made to further improve performance, can be extruded or forging. heavy alloy. Tungsten-based (including the amount of 90 to 98% tungsten), add a small amount of Fe, Ni, Cu and other elements, obtained by liquid phase sintering of the alloy, with a high proportion (16.5 ~ 18.8g/cm), so called heavy alloy. Heavy alloy is divided into W-Ni-Fe and W-Ni-Cu two series, due to their high specific gravity, high strength and strong absorption of X-ray and -ray capabilities, widely used as inertial .ponents, armor-piercing core and storage of radioactive materials and shielding. Since W added Ni, Fe and other elements, so the liquid phase sintering process appear to greatly reduce the sintering temperature, resulting in the so-called "sintering." The proportion of industrial production of high alloy sintering temperature is 1400 ~ 1550. tungsten copper, tungsten, silver alloy false. Tungsten and copper (or silver) alloy does not occur (not the formation of solid solution), nor the formation of .pounds, their physical properties are very different from the system can not take melting process, metal powder supplier but can only use powder metallurgy method from the system. They are a two-phase structure, integrated performance of the two metals .posites, so called "fake alloy." Arc erosion resistant alloys such false high, welding resistance is good, good electrical conductivity, thermal conductivity, as early as the 1930s it was used as electrical switch contact (contact). W-Ag than the W-Cu contact resistance is low, more as a contactor contacts, W-Cu than for high-voltage circuit breaker contact, especially W-20Cu as the most successful high-voltage circuit breaker contact material (see powder metallurgy electrical materials). W-Cu is also used as resistance welding and EDM electrodes. Since at high temperatures, W-Ag and W-Cu, Ag or Cu in the hair with a cooling effect, so since the 1960s has been used as a solid fuel rocket motor nozzle throat insert gas, temperature up to 3000 and more. About the Author: 相关的主题文章: