Metal powder is a metal that has been broken down into a powder form. Metals that can be found in powder form include aluminium powder, nickel powder, iron powder and many more. [1] [2] [3] [4] [5] There are four different ways metals can be broken down into this powder form: [6]
The following processes can be used to produce metal powder: [6]
Spray drying is a method of forming a dry powder from a liquid or slurry by rapidly drying with a hot gas. This is the preferred method of drying of many thermally-sensitive materials such as foods and pharmaceuticals, or materials which may require extremely consistent, fine particle size. Air is the heated drying medium; however, if the liquid is a flammable solvent such as ethanol or the product is oxygen-sensitive then nitrogen is used.
The nickel–cadmium battery is a type of rechargeable battery using nickel oxide hydroxide and metallic cadmium as electrodes. The abbreviation Ni–Cd is derived from the chemical symbols of nickel (Ni) and cadmium (Cd): the abbreviation NiCad is a registered trademark of SAFT Corporation, although this brand name is commonly used to describe all Ni–Cd batteries.
A substance is pyrophoric if it ignites spontaneously in air at or below 54 °C (129 °F) or within 5 minutes after coming into contact with air. Examples are organolithium compounds and triethylborane. Pyrophoric materials are often water-reactive as well and will ignite when they contact water or humid air. They can be handled safely in atmospheres of argon or nitrogen. Class D fire extinguishers are designated for use in fires involving pyrophoric materials. A related concept is hypergolicity, in which two compounds spontaneously ignite when mixed.
Hydrogenation is a chemical reaction between molecular hydrogen (H2) and another compound or element, usually in the presence of a catalyst such as nickel, palladium or platinum. The process is commonly employed to reduce or saturate organic compounds. Hydrogenation typically constitutes the addition of pairs of hydrogen atoms to a molecule, often an alkene. Catalysts are required for the reaction to be usable; non-catalytic hydrogenation takes place only at very high temperatures. Hydrogenation reduces double and triple bonds in hydrocarbons.
Brazing is a metal-joining process in which two or more metal items are joined together by melting and flowing a filler metal into the joint, with the filler metal having a lower melting point than the adjoining metal.
Powder metallurgy (PM) is a term covering a wide range of ways in which materials or components are made from metal powders. PM processes can reduce or eliminate the need for subtractive processes in manufacturing, lowering material losses and reducing the cost of the final product.
Industrial processes are procedures involving chemical, physical, electrical, or mechanical steps to aid in the manufacturing of an item or items, usually carried out on a very large scale. Industrial processes are the key components of heavy industry.
The Castner process is a process for manufacturing sodium metal by electrolysis of molten sodium hydroxide at approximately 330 °C. Below that temperature, the melt would solidify; above that temperature, the molten sodium would start to dissolve in the melt.
Iron pentacarbonyl, also known as iron carbonyl, is the compound with formula Fe(CO)5. Under standard conditions Fe(CO)5 is a free-flowing, straw-colored liquid with a pungent odour. Older samples appear darker. This compound is a common precursor to diverse iron compounds, including many that are useful in small scale organic synthesis.
A foundry is a factory that produces metal castings. Metals are cast into shapes by melting them into a liquid, pouring the metal into a mold, and removing the mold material after the metal has solidified as it cools. The most common metals processed are aluminum and cast iron. However, other metals, such as bronze, brass, steel, magnesium, and zinc, are also used to produce castings in foundries. In this process, parts of desired shapes and sizes can be formed.
Continuous casting, also called strand casting, is the process whereby molten metal is solidified into a "semifinished" billet, bloom, or slab for subsequent rolling in the finishing mills. Prior to the introduction of continuous casting in the 1950s, steel was poured into stationary molds to form ingots. Since then, "continuous casting" has evolved to achieve improved yield, quality, productivity and cost efficiency. It allows lower-cost production of metal sections with better quality, due to the inherently lower costs of continuous, standardised production of a product, as well as providing increased control over the process through automation. This process is used most frequently to cast steel. Aluminium and copper are also continuously cast.
Titanium powder metallurgy (P/M) offers the possibility of creating net shape or near net shape parts without the material loss and cost associated with having to machine intricate components from wrought billet. Powders can be produced by the blended elemental technique or by pre-alloying and then consolidated by metal injection moulding, hot isostatic pressing, direct powder rolling or laser engineered net shaping.
Spray forming, also known as spray casting, spray deposition and in-situ compaction, is a method of casting near net shape metal components with homogeneous microstructures via the deposition of semi-solid sprayed droplets onto a shaped substrate. In spray forming an alloy is melted, normally in an induction furnace, then the molten metal is slowly poured through a conical tundish into a small-bore ceramic nozzle. The molten metal exits the furnace as a thin free-falling stream and is broken up into droplets by an annular array of gas jets, and these droplets then proceed downwards, accelerated by the gas jets to impact onto a substrate. The process is arranged such that the droplets strike the substrate whilst in the semi-solid condition, this provides sufficient liquid fraction to 'stick' the solid fraction together. Deposition continues, gradually building up a spray formed billet of metal on the substrate.
Thermal spraying techniques are coating processes in which melted materials are sprayed onto a surface. The "feedstock" is heated by electrical or chemical means.
The filler metal (FM) alloys that can be produced as amorphous brazing foils (ABF) are eutectic compositions formed by transition metals such as nickel, iron, copper, etc., in combination with metalloids, such as silicon, boron and phosphorus. In conventional crystalline state, all these materials are inherently brittle and cannot be produced in continuous forms such as foil, wire, etc. Therefore, they were available only as powders, pastes, or their derivates. On the other hand, the very presence of metalloids at or near the eutectic concentration promotes the rapid solidification (RS) conversion of such alloys into a ductile amorphous foil.
Gas diffusion electrodes (GDE) are electrodes with a conjunction of a solid, liquid and gaseous interface, and an electrical conducting catalyst supporting an electrochemical reaction between the liquid and the gaseous phase.
Zinc smelting is the process of converting zinc concentrates into pure zinc. Zinc smelting has historically been more difficult than the smelting of other metals, e.g. iron, because in contrast, zinc has a low boiling point. At temperatures typically used for smelting metals, zinc is a gas that will escape from a furnace with the flue gas and be lost, unless specific measures are taken to prevent it.
Ultrasonic nozzles are a type of spray nozzle that use high frequency vibrations produced by piezoelectric transducers acting upon the nozzle tip that create capillary waves in a liquid film. Once the amplitude of the capillary waves reaches a critical height, they become too tall to support themselves and tiny droplets fall off the tip of each wave resulting in atomization.
Bismuth bronze or bismuth brass is a copper alloy which typically contains 1-3% bismuth by weight, although some alloys contain over 6% Bi. This bronze alloy is very corrosion-resistant, a property which makes it suitable for use in environments such as the ocean. Bismuth bronzes and brasses are more malleable, thermally conductive, and polish better than regular brasses. The most common industrial application of these metals are as bearings, however the material has been in use since the late nineteenth century as kitchenware and mirrors. Bismuth bronze was also found in ceremonial Inca knives at Machu Picchu. Recently, pressure for the substitution of hazardous metals has increased and with it bismuth bronze is being marketed as a green alternative to leaded bronze bearings and bushings.
Selective laser melting (SLM) is one of many proprietary names for a metal additive manufacturing (AM) technology that uses a bed of powder with a source of heat to create metal parts. Also known as direct metal laser sintering (DMLS), the ASTM standard term is powder bed fusion (PBF). PBF is a rapid prototyping, 3D printing, or additive manufacturing technique designed to use a high power-density laser to melt and fuse metallic powders together.
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