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Bulk copper, copper-graphene and copper-graphite composites were produced from copper-thermally expanded graphite (TEG) powder mixtures with 0-3 wt.% TEG contents via modified powder metallurgy process that includes powder milling in a planetary mill at 350 rpm for 5 hours, compaction, and vacuum annealing at 1030 °C for 1 hour. Phase composition and microstructure of the composites were analysed by XRD and SEM techniques. According to Raman spectroscopy, TEG transforms into a few layer graphene flakes in case of composites with 0.1-1 wt.% of carbon additive, while for 3 wt.% of carbon additive it remains in the form of graphite. The addition of 0.1 wt.% TEG results in the tensile strength increase up to 160 MPa (from 93 MPa for pure copper specimen synthesized via the similar synthesis route). Vickers hardness obtained for Specimens under the study is independent fromthe composite composition.

According to the XRD results combined with Rietveld refinement of the patterns, 33.3 La O -66.7 ZrO ceramics after solid-state synthesis are composed of well-formed cubic pyrochlore-type La Zr O with 5 wt.% admixture of monoclinic and cubic ZrO whereas 33.3 La O -66.7 ZrO precursor powders after cryochemical synthesis correspond to low-crystalline La(OH) . The components of the La O -ZrO system evaporate separately: there is no temperature range where lanthanum and zirconium gaseous species are present together. It was found that the activities of lanthania have low negative deviation from the ideal case.

Fully stabilized zirconia/graphene composites are very promising advanced structural materials having mixed ion–electron conductivity for energy storage and energy conversion applications. The existing methods of the composite manufacturing have a number of disadvantages that limit their practical use. Thus, the search for new sintering methods is an actively developing area. In this work, we report for the first time the application of the SiC powder bed sintering technique for fully stabilized zirconia (YSZ) composite fabrication. The reduced graphene oxide (rGO) was used as a graphene derivative. As a result, well-formed ceramics with high density and crystallinity, the maximal microhardness of 13 GPa and the values of the ionic conductivity up to 10−2 S/cm at 650 °C was obtained. The effects of the sintering conditions and rGO concentration on the microstructure and conductivities of ceramics are discussed in detail. The suggested powder bed sintering technique in a layered graphite/SiC/graphite powder bed allowed well-formed dense YSZ/rGO ceramics fabrication and can become a suitable alternative to existing methods for various oxide ceramic matrix composite fabrication: both conventional sintering and non-equilibrium (SPS, flash sintering) approaches.

Nickel matrix composites are important materials for various engineering applications. The present paper describes the fabrication of bulk graphene-nickel (Gr-Ni) and reduced graphene oxide-nickel (rGO-Ni) composites by powder metallurgy technique using various graphene sources, namely, thermally exfoliated graphite (TEFG) and reduced graphene oxide (rGO) and the investigation of the mechanical properties of the composites. Homogeneous distribution of graphene derivatives in the composite matrices was confirmed for all compositions by XRD and Raman spectroscopy. It was proved that different Gr sources in the initial powder mixtures result in some different graphene derivatives type in the composites produced. Nevertheless, scanning electron microscopy data demonstrated that the microstructure of the samples produced using the different graphene sources is rather similar. It was shown that the mechanical properties of the composites are very sensitive to the type of graphene derivative chosen at low additive contents. TEFG addition results in the decreased values of tensile strength, ductility, and elongation for all compositions. It was shown that 0.1 wt.% of rGO addition resulted in the 34 % elongation-to-failure increase with no change in the UTS value of composite. The 0.1 wt.% rGO-Ni composite showed the increased elongation and the tensile strength value comparable to pure nickel specimen. Fractography tests revealed the difference in the mechanical behaviour of rGO-Ni and Gr-Ni composites.