International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

The study is devoted to the identification of technological features of the process of hydrovacuum dispersion (atomization) of liquid aluminium, which provides the accompanying self-generation of the effect of sonochemical hydrogenation of the obtained particles. In order to explain this phenomenon, the study reveals the design and functional features of a special, actually developed installation of continuous vertical suction and dispersion of metallurgical melts. Here the graphical scheme-model of influence of ultrafrequency cavitation pulsation generated by shock waves of hydraulic rarefaction, cumulative splitting of water molecules and sonochemical introduction of released hydrogen in solidifying particles of atomized aluminum melt is reconstructed. The results of the revealed sonochemical hydrogenation process are clearly illustrated by both electron microscopy images and X-ray diffractometry and FTIR spectroscopy. It is established that during hydrovacuum atomisation free hydrogen can be dissolved and retained in aluminum microparticles, both with the formation of blown (foamed) clusters of diffusion-amorphous hydrogenation, and – solid solution of embedding, in the form of crystals of face-centred cubic syngony.

In this paper the physical model for high pressure water atomization of metal melts using hydraulic nozzle of a vortex type was proposed. The developed model assumes, that due to high speed water flow with significant centrifugal component of its velocity vector the rarefaction is formed, which causes intensive air suction leading to the formation of rotating gas (vapor-air) layer of toroid-like shape, providing a gap between the water flow and the metal stream. Thus water stream is separated from the heated surface of metal stream and the formation of particles during crystallization of melt droplets occurs due to surface tension mainly in this vapor-air layer. The cooling of melt droplets in the gas-water leads to the formation of spherical powder particles. The proposed model correlates well with the known experimental data on the production of spherical powders using a vortex-type annular hydraulic nozzle.

The possibility of high energy synthesis of Ti–Al–C system powder grain refiner by using high voltage electric discharges for treatment of powder mixtures of 75 % Ti + 25 % Al and 85 % Ti + 15 % Al composition in kerosene with subsequent briquetting by spark plasma sintering is shown in present work. It is found out that high voltage electric discharge treatment of powders leads to the increase of dispersity as well as to synthesis of new carbon containing phases during chemical interaction between system components and products of working hydrocarbon liquid destruction. The possibility of controlling this process by changing initial composition of powders, specific treatment energy and spatial distribution of plasma formations by changing electrode system type is shown. It is also shown that changing master alloy synthesis parameters allows controlling inoculation efficiency. Thereby it is possible to achieve surface or volumetric inoculation, so selective increasing of plastic or strength properties of Ni-based cast superalloys becomes possible. Introduction of 0.01 % of synthesized grain refiner during the casting of SM88U (СМ88У) superalloy allows decreasing mean grain size from 1…2 mm to 0.2…0.5 mm. Tensile strength of inoculated superalloy at the temperature of 900˚С was 68 MPa while their stress rupture strength increased by 20 % in average. Composition and properties of inoculated alloys comply with standard technical documentation, which allows their usage for the
production of gas turbines blades.

A novel technology for producing metal powders is presented, the distinctive feature of which are the conditions of forming of powder particles. In particular, under the proposed technology the melt is sucked bottom-up by the vacuum produced by the toroidal vortex of the discharged nucleus of high-pressure water flow in the two-layer cylindrical shell cavity, where it is being dispersed as metallic particles and carried over from the working medium to a special store. The so produced powders have a particular morphology and structure, increased specific surface area and microhardness.