Obtaining nanopowder pseudo-ligatures Cu–(SiC+Si3N4) for modification and reinforcement of aluminum alloys

Abstract

The mechanical mixing and subsequent compaction of a powder mixture consisting of carrier powder (electrolytic copper (Cu) with particle size of 20–100 μm) with nanopowder modifier compound (powders of silicon carbide (SiC)—50–70%, silicon nitride (Si₃N₄)—20–30%, sodium hexafluoroaluminate (Na₃AlF₆)—10–20%) with particle size of 70–100 nm obtained by azide technology of self-propagating high-temperature synthesis (SHS) were investigated. The mixtures containing 2.5, 5, 10, 15% of the modifier were investigated. Mechanical mixing was carried out for 30–45 min at speed of 150 rpm in a Pulverizette-5 planetary mill. An analysis of mixing of the raw powder components was performed. Some physicotechnological properties of the obtained powder mixtures, such as particle size distribution, density, bulk weight, and flowability, are determined. The formation of briquettes—the nanopowder pseudo-ligatures from powder mixtures of composition Cu–(SiC + Si₃N₄) with different concentration of modifier—was carried out by cold pressing. Compacting of the received mixtures of powders was carried out in cylindrical mold using a PSU-50 hydraulic press under pressure of 85–310 MPa. The dependence of the relative density and porosity of the briquettes on the pressure of pressing is determined. The microstructures of pseudo-ligatures pressed at maximum pressure of pressing are presented. Briquettes—nanopowder pseudo-ligatures with diameter of 25 mm, height up to 2 mm, weight of 5 g, with relative density of 53–85% and porosity of 15–47%—intended for subsequent input to aluminum melt with the aim of inoculation are obtained.