Various metallurgical processes are used to produce copper powder parts from finely flaked copper materials through compaction, consolidation and heating. Copper is a reddish brown nonferrous mineral that can be classified as a transition metal.
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Easily fabricated due to its high ductility, copper is used in a variety of applications for its high corrosion resistance and especially for its good electrical and thermal conductivity. When crushed, this metal can be used alone or in the creation of unique alloys. As powder metallurgy heats raw materials to temperatures just below the melting point in order to compress and combine them, copper powder parts retain all of the desirable attributes of the pure metal regardless of mixing. Metallurgy utilizes the unique properties of copper to produce solid metal parts with the same qualities. These powder metal parts are used in a variety of industries. Electronic, current carrying, architectural, construction, automotive, energy and transport production all employ copper powder parts such as heat sinks, radiators, chillers, crucibles, tubes, pipes and fittings. The use of press-and-sinter processes when forming copper parts is popular as it results in little waste. As much as 97% of the raw copper used in manufacturing ends up in the finished parts. When handling the powder, caution should be taken as it can cause irritation to skin, eyes and respiratory tract as well as the liver and kidneys in instances of prolonged exposure.
There are three basic steps to powder metallurgy, the process used to create copper powder parts. First, any of a number of techniques including atomization, flaking, pulverization, chemical reduction, and electrolytic are used to reduce the initial raw copper to a fine dust or powder. Specific amounts of this powder are then placed into the compaction die or mold where pressure is applied from both above and below in precise amounts relevant to the specific materials and intended use of the finished product. After the resulting form is ejected from the die, sintering is used to fuse the powder particles together. The parts are placed on a moving belt which draws them through a controlled-atmosphere furnace, heating the compressed powder to just below the melting point of the raw materials. For copper, the melting point is 1981 degrees Fahrenheit. Sintering occurs at about 2/3 of this temperature or 1321 degrees Fahrenheit. In this manner, the mechanical bonds of raw copper are converted into metallurgical bonds creating solid mass from the powder. While powder metallurgy results in objects close to the finished product, a variety of secondary processes may be used to create application specific copper powder parts. Secondary operations include sizing, coining, infiltration, heat treating, machining, plating, drilling, grinding, reaming and resin impregnation.
