Shlonsky P. Explosive welding technology of copper-aluminum coaxial conductors

The dissertation is devoted to the studying of the structure and mechanical properties of copper and aluminum coaxial joints obtained by explosion welding (EW) and the creation of equipment for this process. The analyzes of the methods of coaxial joints obtaining was fulfilled. The advantages of EW over other methods of copper with aluminum joining were established. The relevance of equipment for EW creating is also shown. The microstructure of the connection of copper and aluminum obtained by means of EW in flat and coaxial schemes is investigated. It has been established that welding on the same energy mode more intermetallics are formed in the coaxial joint, which is due to the absence of lateral leakage of shock-compressed gas. The term was introduced and the phenomenon of "channel effect" in EW was experimentally studied. The mass transfer ratio of metal particles from the surfaces to be joined was evaluated during EW of the plates of steel 20. It was found that the thickness of the metal layer, which is ripped off to the surface of the plate was 30 μm, which is 4..7 times higher than the estimating calculation. This increase in the mass of the cumulative jet leads to a decrease in its velocity and the capture of its content in a vortex. The chemical composition of vortices on copper-aluminum bimetal samples was studied. It is established that Al2Cu (θ-phase, ~ 28.2-29% Al) and AlCu (η-phase, ~ 46-46.7% Al) structures are formed during welding in air, and when welding in vacuum-type Al3Cu (ζ-phase, ~ 24.6-25.3% Al) and alloy eutectic Al-Al2Cu. Phases appeared in vacuum have more electrical conductivity. The microstructure and mechanical properties of a copper-aluminum bimetallic rod with a degree of compression of 90% during drawing and subsequent exposure at different temperatures were studied. It was found that during exposure for a period of one hour at a temperature of 300 ° C a layer of intermetallics 1-2 μm thick is formed, and during the same period at a temperature of 350 ° C a layer of intermetallics 4-5 μm thick is formed. The relative elongation of tensile samples after cold drawing increases from 11.6% in the initial state to 57.5% after heat treatment. A numerical method for determination of the stress-strain state of the tubular chamber power elements during an explosion of a flat explosive charge has been developed. The calculated values of stresses are satisfactorily correlated with the experimental results. Additionally the stress-strain state in the elements of the tubular explosive chamber was experimentally investigated and a criteria of the critical stress state in elements of the chamber was suggested. A tubular explosive chamber with an automated process of billets loading into EW has been developed, it increases the productivity of the process. The calculation method of optimal geometrical parameters choice for an aluminum bar and a copper tube was developed. A special form of aluminum billet is proposed, which has a number of practical advantages. The results of the research are the basis for the development of the technology of copperaluminum power lines manufacturing with a thin (300 μm) copper layer for control systems of aircraft company "Antonov". The influence of the filler matter inside inner tube during external cladding was experimentally investigated to preserve the shape of the workpiece. A special design of the container for backfilling explosives was developed, which ensured uniformity of backfilling. A combined technology (EW + friction welding) for obtaining bimetallic sleeves for connecting flexible multi-core wires at the request of a South Korean company has been developed.