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The process of advanced aluminum-alumina powders production for selective laser melting was studied. The economically effective method of obtaining aluminum-alumina powdery composites for further selective laser melting was comprehensively studied. The aluminum powders with 10–20 wt. % alumina content were obtained by oxidation of aluminum in water. Aluminum oxidation was carried out at ≤200 °C. The oxidized powders were further dried at 120 °C and calcined at 600 °C. Four oxidation modes with different process temperatures (120–200 °C) and pressures (0.15–1.80 MPa) were investigated. Parameters of aluminum powders oxidation to obtain composites with 10.0, 14.5, 17.4, and 20.0 wt. % alumina have been determined. The alumina content, particle morphology, and particle size distribution for the obtained aluminum-alumina powdery composites were studied by XRD, SEM, laser diffraction, and volumetric methods. According to the obtained characteristics of aluminum-alumina powdery composites, they are suitable for the SLM process. [ABSTRACT FROM AUTHOR]

The process of advanced aluminum-alumina powders production for selective laser melting was studied. The economically effective method of obtaining aluminum-alumina powdery composites for further selective laser melting was comprehensively studied. The aluminum powders with 10-20 wt. % alumina content were obtained by oxidation of aluminum in water. Aluminum oxidation was carried out at ≤200 °C. The oxidized powders were further dried at 120 °C and calcined at 600 °C. Four oxidation modes with different process temperatures (120-200 °C) and pressures (0.15-1.80 MPa) were investigated. Parameters of aluminum powders oxidation to obtain composites with 10.0, 14.5, 17.4, and 20.0 wt. % alumina have been determined. The alumina content, particle morphology, and particle size distribution for the obtained aluminum-alumina powdery composites were studied by XRD, SEM, laser diffraction, and volumetric methods. According to the obtained characteristics of aluminum-alumina powdery composites, they are suitable for the SLM process., Competing Interests: The authors declare no conflict of interest.

Yields of liquid products (bio-oil and residual organics in aqueous solution) of hydrothermal liquefaction (at 300℃ and 60 min) of own cultivated Arthrospira platensis using different solvents have been determined. Nonpolar hexane, moderately polar dichloromethane, and relatively more polar acetonitrile have been used. High-resolution mass spectrometry based on linear quadrupole ion trap and Fourier transform mass spectrometer (LTQ FT) has been used for liquid sample characterization. Concentration of bio-oil in a unit of solvent volume after solvent extraction took the following arrangement: acetonitrile > dichloromethane > hexane. Concentration of residual organics in a unit of aqueous solution after solvent extraction took the following arrangement: hexane >dichloromethane > acetonitrile. Yield of total organics was arranged as follows: hexane > dichloromethane > acetonitrile. Content of carbon in bio-oil was increased and the content of oxygen was decreased with the increasing of solvent polarity. From mass spectrometric analysis it was established that in the positive electrospray ionization (ESI) mode the compounds containing two nitrogen atoms dominate and the considerable portion of the compounds containing single nitrogen atom are also presented for both bio-oil and residual organics samples. In the negative ESI mode the compounds containing four oxygen atoms dominated except bio-oil obtained using hexane where the compounds containing two oxygen atoms dominated. Bio-oil fraction had highly saturated compounds with low double bond equivalent values while the compounds of the residual organics fraction had large double bond equivalent values.