Fine Copper Powders Production

The article is devoted to the description of a method for producing electrolytic copper powder with an average particle size of 3 to 10 μm. In order to increase the proportion of the finely dispersed fraction during the electrolysis process, the composition of the electrolyte was changed. In particular, the content of chloride ions was increased from 6 to 53 mg/dm3. After the growth of the powder in industrial baths, its subsequent drying and sieving on vibrating screens, samples were obtained with a fraction of 5 μm content in the range from 3 to 38 %. Additionally, air classification of powders was carried out at various speeds of the classifier rotor from 800 to 2000 rpm. Based on the results of the study, the optimal ranges of the specific surface area and the size of the initial powder particles before classification, as well as the composition of the electrolyte and the operating modes of the classifier, were determined.

Friction Sintering of Copper Powder Using a New Rapid, Cost Effective and Energy Efficient Process

Dendritic electrolytic copper powder was sintered using a newly developed friction sintering process. Green copper pellets of 14 mm height and 16 mm diameter were prepared at room temperature with 5-ton load and 60 seconds holding time. The pellets were sintered using a newly developed rapid, cost-effective, energy efficient, green friction sintering process that allows for easy and quick removal of sintered products. An aluminum plate of 14 mm thickness and 16.1 mm diameter through hole was used to hold green pellets during sintering. Frictional heat and pressure were applied on a top plate through a rotating 18 mm diameter, flat shoulder, WC tool. Sintering was performed at 12 kN axial load and 800 rpm tool rotational speed. Sintering temperatures were measured using K-type thermocouples. SEM (scanning electron microscope) images of fractured surfaces for sintered pellets show neck formation between copper particles. The neck formation is approximately uniform throughout the depth. This is in-line with hardness results along the thickness of the pellet. The process holds promise particularly for solid-state sintering of metal based powders.

Electrical conductivity of poly (L lactic acid) and poly (3-hydroxybutyrate) composites filled with galvanostatically produced copper powder

This manuscript presents experimental studies of composite materials based on poly (L lactic acid) (PLLA) and poly (3-hydroxybutyrate) (PHB) matrices filled with electrolytic copper powder, having a very high dendritic structure. Volume fractions of the copper powder used as filler in all prepared composites were varied in the range 0.5-6.0 vol.%. Samples were prepared by hot moulding injection at 170 ?C. Influence of particle size and morphology, as well as the influence of matrix type on conductivity and percolation threshold of the obtained composites were examined. Characterization included: electrical conductivity measurements using AC impedance spectroscopy (IS), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and Fourier-transform Infrared spectroscopy (FTIR). Presence of three-dimensional conductive pathways was confirmed. The obtained percolation thresholds of 2.83 vol.% for PLLA and 3.13 vol.% for PHB composites were measured, which is about three times lower than the ones stated in the literature for similar composites. This property is ascribed to different morphologies of the filler used in the present investigation.