Ammonium perrhenate (APR) is an intermediate product in rhenium extraction process, by which it is possible to produce rhenium powder. The main purpose of this research is to investigate the behaviour of APR in different atmospheres as a part of reduction process. In this research, differential thermal analysis and thermo gravimetric analysis are used to peruse the APR behaviour in nitrogen, argon and hydrogen atmospheres. Also for further validation, X-ray diffraction analysis and the scanning electron microscopy were used. The results indicate that APR behaves almost the same in the argon and nitrogen atmospheres. In these conditions, APR decomposes to rhenium oxides during thermal decomposition. However, APR in hydrogen reductive atmosphere is reduced to pure rhenium powder without any reactions. SEM images showed that hydrogen reduced APR had a spherical morphology, but on the other hand the directly reduced rhenium powder in hydrogen atmosphere showed flake morphology.

In this paper, the copper-based nanocomposites with TiO2 nanoparticles were synthesized by the self-propagating high-temperature synthesis (SHS) process. The effect of the different amounts of excess copper, in comparison with the stoichiometric ratio (CuO:Ti ratios of 1:1, 2:1, and 3:1), on the phase formation of achieved samples was studied. A thermodynamical study showed that increasing the excess copper powder reduces the adiabatic temperature, which helps the phase formation. The maximum Brinell hardness (89) was obtained for the sample with the CuO:Ti ratio of 1:1. Finally, the wear behavior of the synthesized nanocomposites was evaluated by the pin on disk test, and the variation of friction coefficient and lost weight were measured. The friction coefficient decreased by the formation of phases and distribution of titanium oxide particles during the SHS process in the presence of the stoichiometric ratio of CuO:Ti. Therefore, the wear behavior was improved. The lowest depth of wear trace was measured 0.68 where the ratio of CuO: Ti was 1:1.