Study of the Influence of the Granulometric Composition of Electrospark Cobalt-Chromium Powders on the Physical and Mechanical Properties of Additive Products

Purpose of research.The purpose of this work is to study the influence of the granulometric composition of electrospark cobalt-chromium poweders on the physico-mechanical properties of additive products.

Methods. Wastes of cobalt-chromium alloy“CELLIT" was chosen for this research.Butyl alcohol was chosen as a working fluid. To obtain cobalt-chromium powder materials by electrospark dispersion, a unit for ESD of conductive materials was used. The dispersed material was charged into a desiccator filled with butyl alcohol used as a working fluid for dispersion. Butyl alcohol C₄H₉OH belongs to monatomic alcohols. It is a colorless slightly viscous liquid with a peculiar smell of fusel oil,miscible with organic solvents.Butanol is used as a solvent in the paints and coatings industry, in the manufacture of resins and plasticizers, and in many other industries. To obtain experimental samples of additive products, the unit for lamination of powder materials by plasma was used. The authors studied the granulometric composition of the obtained powders by the method of ultrasonic dispersion in a liquid. The research methodology is FR 1.27.2009.06762 "Technique of particle size measurements in suspensions, emulsions and aerosols in nanometer and colloidal ranges with the use of dynamic light scattering effect".

Results. Experiments proved that the conditions of production and dispersion of powders determine their behavior during sintering.With the increase ofthe dispersion of the powder, sintering process accelerates and proceeds more actively, and the mechanical properties of the resulting products improve.Intensification of powder sintering is facilitated by oxides contained in large quantities in fine powders and reduced when heated during their sintering. The sponge metal surface, formed after the disappearance of the oxide, is more active than the surface, which is initially free from the oxide film.With the increase of dispersion and specific surface area of the powder, its penetration increases, the porosity decreases, and the microhardness increases. The presence of powder particles of different fractions increases the density of its shrinkage by filling cavities and micropores at the joints of large particles, which further leads to the decrease of the roughness of sintered products and the increase of the ultimate compressive and bending strength.

Conclusion. The conducted research reveals the relationship between the technology of electrospark cobalt-chromium powders production and physico-mechanical properties (porosity, microhardness, ultimate compressive strength, ultimate bendingl strength, roughness of the surface layer, etc.) of the experimental samples, and also allows controlling the process of the formation of structure and properties of products obtained by additive technologies.

cobalt-chromium alloy, wastes, electrospark dispersing, powder, additiveproducts, physical and mechanical properties

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