The production and properties of spherical copper powders and parts from such powders

Abstract

1. Copper powders produced by the methods of plasma spraying and melting of nonspherical powder particles consist of particles which are nearly spherical and have a smooth surface. 2. With the plasma spraying method, copper-wire scrap can be used for producing spherical powder. This method gives a high percentage yield of spherical particles; by regulating conditions of preparation, it is possible to alter the quantitative yield of any powder fraction. 3. The method of powder preparation by melting gives a 100% yield of spherical particles; the resultant powder may be made to consist of particles belonging almost exclusively to one fraction. The deviation from the size range of the required fraction is small and does not extend beyond the neighboring fractions. 4. A study of the formation of parts from spherical powders demonstrated that, by employing compacting, it is possible to produce parts of the required porosity, but this is accompanied by particle deformation. With freely poured powder, the residual porosity is 40–50%. Vibratory densification permits the porosity to be lowered to 35%. The use of vibratory densification is particularly effective in the manufacture of thin-walled parts of complex configuration. 5. The vibratory densification of different powder fractions takes place at different frequencies and amplitudes. The vibratory densification process may be intensified by applying low static pressures. 6. A study of materials obtained by sintering powders with a 0.3% phosphorus addition at a temperature of 1000°C demonstrated that the strength properties of materials are independent of the powder preparation method. The bending strength is 35–55 MN/m2.