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The wetting behavior was measured for Al2O3-C in contact with AlSi7Mg with a conventional sessile drop test (vacuum, 950 &deg, C and 180 min) and a sessile drop test with a capillary purification unit (vacuum, 730 &deg, C and 30 min). The conventional test yielded contact angles of around 92&deg, whereas the sessile drop measurement with capillary purification showed a strongly non-wetting behavior with a determined apparent contact angle of the rolling drop of 157&deg, Filtration tests, which were repeated twice, showed that the Al2O3-C filter possessed a better filtration behavior than the Al2O3 reference filter. For both filtration trials, the PoDFA (porous disc filtration analysis) index of the Al2O3-C filter sample was equal to half of the PoDFA index of the Al2O3 reference filter sample, indicating a significantly improved filtration performance when using Al2O3-C filter. Notable is the observation of a newly formed layer between the aluminum and the Al2O3-C coating. The layer possessed a thickness between 10 &micro, m up to 50 &micro, m and consisted of Al, C, and O, however, with different ratios than the original Al2O3-C coating. Thermodynamic calculations based on parameters of the wetting and filtration trials underline the possible formation of an Al4O4C-layer.

Aiming at the problem that melt inclusions in the casting process of 7085 aluminum alloy seriously affect the ingot quality, this study introduces ultrasonic bending vibration into the melt of the launder in the semi-continuous casting process of 7085 aluminum alloy and investigates the online purification effect of ultrasonic bending vibration on the melt of 7085 aluminum alloy through a metallographic analysis, SEM analysis, and EDS energy spectrum analysis. The results show that, under the action of the ultrasonic, the inclusions in the aluminum melt are transformed from a large number of elongated large inclusions with a size of more than 50 μm, and granular inclusions with a size of about 5–15 μm, into a small amount of smaller than 30 μm point-like small inclusions. In addition, the average area ratio of inclusions in the melted sample was reduced from 3.835 (±0.05)% to 0.458 (±0.05)%, and the residual refining agent in the aluminum melt was effectively removed. It was also found that under the action of ultrasonic bending vibration, the tiny inclusions in the melt aggregate with each other, and interact with the residual refining agent in the melt to further grow, and are attached to the inner surface of the ceramic cavity channel to be removed.

A mathematical model has been developed for single bubble motion and mass transfer for aluminum degassing under a compound field of ultrasonic and rotating flow, and it showed good agreement with experimental data. The effects of the ultrasonic frequency and acoustic pressure on the bubble size, bubble trajectory, and mass transfer rate between the bubble and melt were investigated. The ultrasonic frequency and acoustic pressure had little effect on the bubble trajectory, and its curve radius gradually increased with increasing distance. The retention time of the bubble in the compound field was much greater than that in a single rotating flow field, which is conducive for improving the purification efficiency. Under the experimental conditions of 450 rpm rotation speed and 1.1 m/s gas flow rate, the optimal parameters are a frequency of 50 kHz and an acoustic pressure of 100 kPa.

Представлены результаты расчета поверхности растворимости компонентов в металле для системы Al–Mg–O. Результаты расчетов сопоставлены с собственными и литературными экспериментальными данными. Results of calculations of the surface of component solubility in metallic melt for the Al–Mg–O system are presented and compared with the author’s and literary experimental data. Трофимов Евгений Алексеевич, кандидат химических наук, доцент кафедры общей металлургии, Южно-Уральский государственный университет, филиал в г. Златоусте. 456209, Челябинская обл., г. Златоуст, ул. Тургенева, 16. Тел.: (3513)665829. E-mail: tea7510@gmail.com Trofimov Evgeny Alexeevich, candidate of chemical science, associate professor of the General Metallurgy department, Zlatoust Branch, South Ural State University. 16 Turgenev street, Zlatoust, Chelyabinsk region, Russia 456209. Tel.: (3513)665829. E-mail: tea7510@gmail.com