Vol 27, No 2 (2018)

The aim of this work was to transform carbon-containing ammonium oxalate, (NH₄)₂C₂O₄, and ammonium acetate, NH₄CH₃CO₂, into 3D graphene-like carbon nanomaterials via magnesiothermic reduction. Both raw and purified products were characterized by XRD, SEM, TGA, and Raman spectra. The conversion of the initial amount of carbon (in salts) into solid carbon (in purified product) varied between 8.5% (for oxalate) and 90.0% (for acetate). The XRD results confirmed the absence of starting salts in the raw products (MgO and C). The purified product was found to contain largely the turbostratic carbon forming a petal-like 3D graphene material. The application potential of synthesized materials was demonstrated on the example of the removal of 4-chlorophenol from its aqueous solution.

Aluminum conductors joining is an important issue in electric transportation industry. In some conditions, electric arc welding or friction stir welding could not be used to join these conductors due to environmental conditions, lack of welding tools, etc. In these cases, SHS method can be used as an appropriate process. In this work, two aluminum conductors (with 9.3-mm diameter and 125-mm length) were joined by SHS method. The conductors were made of commercially pure aluminum (Al > 99%) and, to enhance the joint strength, different weight percentages of copper (0.73–2.4 wt %) were added to green blends. The joints were characterized by hardness testing, electrical resistance, and optical metallography. With increasing Cu percentage, the electrical conductivity of the joint was found to decrease while the strength and hardness, to increase. In the presence of copper, the grain size of the join material was found to decrease.

The gravity-assisted combustion synthesis of γ-TiAl from oxide raw materials by using Al–Ca mixture as a reductant was explored. The use of Al–Ca reductant markedly increased the yield of TiAl and decreased the amount of residual contaminants (such as oxygen, nitrogen, carbon) in target product.

In this work, sugarcane bagasse ash (BA) was used as a low-cost starting material for synthesizing nanosized SiC powder as an alternative to existing techniques for utilizing ever increasing amounts of industrial BA wastes. Fine SiC powder was SHS-produced from BA–C–Mg mixtures and characterized by XRD and SEM. The product powder was found to contain SiC, MgO, and a minor amount of Mg₂SiO₄. Unwanted MgO and Mg₂SiO₄ were leached out with acid solutions. The leached product represented the agglomerated powder of nanoparticles with a mean size of about 50 nm. Our approach can help not only to diminish harmful effects caused by ash disposal but also to suggest a cost-effective process for production of fine SiC powder.

Crystalline Mg_1–xCdxFe₂O₄ ferrites (x = 0.2, 0.4, 0.6, 0.8) were prepared by using simple low-cost solid-state technique and characterized by XRD, FTIR, SEM, and electromagnetic measurements. Low coercivity of synthesized ferrites makes them suitable for low- and high-frequency applications.