Molybdenum metal powder

Manufacturing Processes. Ammonium molybdate or molybdenum trioxide is reduced to molybdenum metal powder by hydrogen in a two-stage process. In the first stage, MoO or ammonium molybdate is reduced to molybdenum dioxide, M0O2, at temperatures around 600°C in the... 

Ammonium molybdates are used to prepare high purity grade molybdenum metal powder, sheet, or wire for colorimetric analysis of phosphates and arse-... 

Molybdenum hexacarbonyl usually is made by treating molybdenum pen-tachloride with zinc dust in carbon monoxide under high pressure (90 to 120 atm). Also, it can be prepared by direct combination of molybdenum metal powder with carbon monoxide under pressure. 

In the case of fluorine and chlorine, molybdenum metal powder reacts with the elemental halogen to give the higher halides in accordance with the general equation... 

The reaction of molybdenum metal powder with an excess of iodine in a sealed tube at 300°C. gives MoI8.1 An earlier preparation which gives a less pure product is the reaction of... 

Mo(CO)6 with iodine in a sealed tube at 105°C.17 The thermal dissociation of Mol at 100°C. in a vacuum is reported to give M0I2.1 The sealed-tube furnace reaction of iodine with molybdenum metal powder at 300-400°C.19 as well as the thermally induced reaction of MoCI with fused lithium iodide1 are mentioned. 

Molybdenum(III) chloride has been prepared in limited quantities by the reduction of molybdenum(V) chloride with hydrogen or molybdenum metal powder.1 2 The procedures give low yields and require several steps. The new procedure described here for the preparation of molybdenum (III) chloride gives a high yield and involves reduction of pure molybdenum(V) chloride, using anhydrous tin(II) chloride as a reducing agent. 

Dry lubricants are usually added to the powder in order to decrease the friction effects. The more common lubricants include zinc stearate [557-05-17, lithium stearate [4485-12-5] calcium stearate [1592-23-0] stearic acid [57-11-4] paraffin, graphite, and molybdenum disulfide [1317-33-5]. Lubricants are generally added to the powder in a dry state in amounts of 0.25—1.0 wt % of the metal powder. Some lubricants are added by drying and screening a slurry of powder and lubricant. In some instances, lubricants are appHed in Hquid form to the die wall. 

Powder Formation. Metallic powders can be formed by any number of techniques, including the reduction of corresponding oxides and salts, the thermal dissociation of metal compounds, electrolysis, atomization, gas-phase synthesis or decomposition, or mechanical attrition. The atomization method is the one most commonly used, because it can produce powders from alloys as well as from pure metals. In the atomization process, a molten metal is forced through an orifice and the stream is broken up with a jet of water or gas. The molten metal forms droplets to minimize the surface area, which solidify very rapidly. Currently, iron-nickel-molybdenum alloys, stainless steels, tool steels, nickel alloys, titanium alloys, and aluminum alloys, as well as many pure metals, are manufactured by atomization processes. 

Cobalt-chromium alloy (see Chromium and chromium compounds) Cobalt-chromium-molybdenum alloys (see Cobalt and cobalt compounds) Cobalt metal powder (see Cobalt and eobalt compounds)... 

The fuels are finely powdered metals (2.0-10.0 g) among which titanium, zirconium, manganese, tungsten, molybdenum and antimony are very common. Sometimes, non-metal powders such as boron and silicon (for fast burning delays), binary alloy powders such as ferrosilicon, zirconium-nickel, aluminum-palladium and metal compounds such as antimony sulfide, calcium silicide etc. are also used. 

The Eulr2 alloy was prepared by direct combination of the metals. Europium chips, % in. on edge were placed in a V4 in.-diameter cavity of a die. Iridium metal powder, —325 mesh and 99.9% pure, was sprinkled over the rare earth element, and the mixture was compressed at 5000 psi. The compressed pellet was placed in a molybdenum boat, which then was transferred to a quartz sleeve, followed by insertion into a quartz reaction tube. The tube was attached to a glass vacuum line and evacuated. Argon was added to approximately 1 atm and the compressed pellet was heated to 900° C and held at the temperature for 14 hr. The product was air quenched to room temperature. The product was crushed in an agate ball mill, compressed into a pellet again, and reheated in the same manner as before. 

The reaction between molybdenum hexacarbonyl and elemental fluorine at —65° results in the formation of Mo2F9, which upon thermal degradation produces molybdenum pentafluoride as one of the products.1 Other syntheses of molybdenum pentafluoride include the reduction of molybdenum hexafluoride with phosphorus trifluoride,2 tungsten hexacarbonyl, or molybdenum metal at high temperatures3 and the oxidation of powdered molybdenum metal with elemental fluorine at 900°.3 The present method consists in the reaction of molybdenum hexafluoride with powdered molybdenum metal at 60° and results in the formation of pure molybdenum pentafluoride in yields of 80% and greater. 

Loose molybdenum disulphide powder has only a limited tendency to adhere to solid surfaces. Very fine powders will attach loosely to metal surfaces, but the coarser grades commonly used for lubrication will not. However, there are several techniques which will produce soft adherent coatings. 

The flotation process used by Matsunaga and Tsuya involves floating fine molybdenum disulphide powder on the surface of a liquid, and lifting it off onto the surface of a flat metal plate. After the liquid is removed by draining and drying, a weakly-adherent thin uniform film of the powder is left on the metal surface. The film appears to consist of randomly-oriented crystals, and has been extensively used for research purposes, but not for use in practical machinery. 

Molybdenum disulphide itself is most reliably considered as a semi-conductor (see Chapter 4), and if used as a continuous film over the contact surfaces it forms a high-resistance layer. Attempts to overcome this problem have included coatings containing metal powder and molybdenum disulphide and very thin molybdenum disulphide films formed in by burnishing" or by sputtering . The in situ and... 

The implication of this work is that the presence of a burnished film on a metal surface should help to improve lubrication by a mineral oil, especially where there might otherwise be some tendency for partial oil starvation. It should be remembered, however, that this film was produced by burnishing molybdenum disulphide powder. Commercial dispersions, bonded films, composites or greases, as well as fully formulated lubricating oils all contain other substances which may significantly affect wetting behaviour. 

It has been involved in many industrial explosions. Explodes on contact with aluminum + barium nitrate + potassium nitrate + water. Forms explosive mixtures with aluminum powder + titanium dioxide, ethylene glycol (240°C), cotton lint (245°C), furfural (270°C), lactose, metal powders (e.g., aluminum, iron, magnesium, molybdenum, nickel, tantalum, titanium), sulfur, titanium hydride. Reaction with ethanol + heat forms the explosive ethyl perchlorate. Violent reaction or ignition under the proper conditions with aluminum + aluminum fluoride, barium chromate + mngsten or titanium, boron + magnesium + silicone rubber, ferrocenium diammine-tetrakis(thiocyanato-N) chromate(l —), potassium hexacyanocobaltate(3—), A1 +... 

Magnesia, magnesium carbonates, magnetite, malcic anhydrate, manganese dioxide, metal powders, molding compounds, molybdenum, monocalciumphosphate (MCP)... 

X-ray Diffraction of Pure MoFe, High Temperature Form. X-ray diffraction powder photographs of MoFe taken at 10 °C. can be indexed on the basis of a body-centered cubic unit cell with a lattice constant, a = 6.23 zb 0.01 A. The similarity of the MoFe diffraction pattern to that of molybdenum metal indicates that the molybdenum atoms in the hexafluoride, as in the metal, are located at the body center and comers of a cube. 

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