The primary application of copper powder is the mixing […]
The primary application of copper powder is the mixing of copper and tin powder to make bronze parts. In the early 1920s, Metal Refining (USMR), located in the Cartwright Autonomous Region of New Jersey, USA, began to produce electrolytic copper powder. This factory has a small area and a large cathode tank. During the peak production period, the powder factory is about 455 tons of copper powder per month. In the mid-1980s, smelting and electrolytic refining companies were forced to close. Due to the closure of the Cartwright plant, although some companies tried to produce electrolytic copper powder, the United States no longer produced electrolytic copper powder products. Today, electrolytic copper powder is produced in Europe, Japan, Russia, India and South Korea.
The electrolytic copper powder particles have dendritic characteristics, the loose packing density is less than 1 g/cm3 through the adjustment process, and the green strength is greater than 35MPa. By adjusting the sedimentation process and powder post-treatment, the bulk density can be increased.
In the United States, copper powder can be produced through water atomization and gas atomization processes plus oxidation-reduction methods, and its shape is spherical or irregular. The physical properties of the atomized powder (such as: bulk density, fluidity, particle size and green strength) are related to the process conditions, such as: specific additives, melting temperature, atomization pressure, reduction temperature and post-treatment of the powder. The median diameter of the powder after oxidation and reduction is 10 microns, the bulk density is less than 1.5 g/cm3, and the green density is greater than 20 MPa. The particle size and reduction temperature of the atomized powder are the key factors that determine the powder product.
The properties of the atomized and redox powder are basically the same as those of the electrolytic copper powder in application, except for the application of dendritic powder and very low bulk density.
Processing self-lubricating copper-tin-based oil-retaining bearings (with internal pores) is a unique feature of powder metallurgy. Such bearings are sintered to a certain density, and the pore oil content can reach 10-30%. Such bearings require regular lubrication to ensure safe operation during the equipment life cycle. In 1920, self-lubricating bearings were first used in Buick cars. The use in other industries is quite large, changing the industry of household equipment. The manufacture of self-lubricating bearings consumes approximately 55% of copper powder output.
Cu-Pb and Cu-Pb-Sn bearings are used in automobiles, turbines, thrust washers and industrial pump equipment. The steel backing material has replaced the cast and forged bronze bearings. The powder is covered on the steel substrate, and a certain density is achieved through sintering and rolling. The porosity of the final product is less than 0.25%.
Brass powder and nickel-silver alloy powder are produced by atomization. The zinc content in the brass powder is 10%-30%. Sometimes lead is added to improve the mechanical properties. It has been used in locks, instrument pointers and driving equipment. Because of its beautiful color, brass is used for decorative metal medals. Brass powder metallurgy parts weighing 2.6 kilograms have recently been used in robot arm parts. The sintered part with a sintered density of 7.7 g/cm3 has a tensile strength of 193MPa and an elongation of 14%. A large number of powder metallurgy parts show that the use of powder metallurgy technology for copper-based materials is very potential and creative.
In 2002, the world's use of copper powder was estimated to be 59-64,000 tons, North America used 22,000 tons, Europe 18,000 tons, and other countries consumed 4,500 tons. About 55% copper powder is used for bronze parts, 13% is mixed with iron powder to produce powder metallurgy parts, 12% is used for infiltration sintering powder, 10% is used for brass, and 10% is used for other applications such as: friction materials, chemistry, W-Cu and Mo-Cu heavy metals, coatings, paints, pastes and inks.
Powder production companies in North America and around the world have been merged and reorganized. Twenty years ago, there were mainly eight copper powder manufacturers in North America. Today, the number has been reduced to four, which may shrink further.