Advances in biomedicine and development of modern technologies in the last century have fostered the improvement in human longevity and well-being. This progress simultaneously initiated the need for novel biomaterials. Recently, degradable metallic biomaterials have attracted serious attention in scientific and clinical research owing to their utilization in some specific applications. This work investigates the effect of the polyethylene glycol (PEG) coating of open-cell iron and phosphorus/iron foams on their microstructure and corrosion properties. The addition of phosphorus causes a slight increase in pore size and the deposition of a polymer coating results in a smoothened surface and a moderate decrease in pore diameter. The PEG coating leads to an increase in corrosion rates in both foams and potentially a more desirable product.

Al₂O₃ with SiC, silver, and graphene nanoplatelets (GNPs) powder mixture was produced by ball milling using ethanol as dispersion media. The GNP-reinforced Al₂O₃-SiC-Ag ceramic–metal composites were densified by spark plasma sintering technology (SPS). A homogeneous dispersion of GNPs in Al₂O₃-SiC-Ag was observed from the sintered samples, and the GNPs were embedded between the grains, which resulted in increasing the contact area. The trans-granular mechanism of crack propagation becomes increasingly dominant by adding GNPs. The hardness reaches 27 GPa, as tested by the Vickers microhardness method, which reflects an increase of 11% compared to Ag-GNPs-free Al₂O₃-SiC. On the other hand, by adding Ag-GNP content, the improvement in density is limited. Wear mechanisms, as determined through ball-on-flat testing, including adhesion, abrasion, and microcracks, are observed and discussed. The composite demonstrated remarkable self-lubricating properties, exhibiting a lower coefficient of friction (COF) and wear rate in an air environment compared to monolithic Al₂O₃-SiC. This improvement is attributed to the formation of a self-lubricating film, enabled by the uniform distribution of Ag and GNPs within the Al₂O₃-SiC matrix. The findings of this study propose a novel material design approach for developing self-lubricating ceramic composites with hybrid solid lubricants.

In this study, we investigate the effect of small amounts of zirconium alloying the medium-entropy alloy (TiVNb)₈₅Cr₁₅, a promising material for hydrogen storage. Alloys with 1, 4, and 7 at.% of Zr were prepared by arc melting and found to be multiphase, comprising at least three phases, indicating that Zr addition does not stabilize a single-phase solid solution. The dominant BCC phase (HEA₁) is the primary hydrogen absorber, while the minor phases HEA₂ and HEA₃ play a crucial role in hydrogen absorption/desorption. Among the studied alloys, Zr4 (TiVNb)₈₁Cr₁₅Zr₄ shows the highest hydrogen storage capacity, ease of activation, and reversibly retrievable hydrogen. This alloy can absorb hydrogen at room temperature without additional processing, with a reversible capacity of up to 0.74 wt.%, corresponding to hydrogen-to-metal ratio H/M = 0.46. The study emphasizes the significant role of minor elemental additions in alloy properties, stressing the importance of tailored compositions for hydrogen storage applications. It suggests a direction for further research in metal hydride alloys for effective and safe hydrogen storage.

Alumina (Al₂O₃) ceramics are interesting for low-weight and mid-high temperature applications. The addition of indium (In) and graphene nanoplatelets (GNPs) can be used to reduce the density and modify the functional properties and mechanical performance of the ceramic matrix. GNP and In-reinforced Al₂O₃ matrix composites were prepared by the spark plasma sintering (SPS) technique. Monolithic Al₂O₃ and Al₂O₃ matrix composites with either 5 or 10 wt.% of In and 2 wt.% of GNPs (Al₂O₃-5In-2GNPs and Al₂O₃-10In-2GNPs) were compacted into disc-shaped samples. The microstructure was studied and characterized with light-optical microscopy (LOM) and scanning electron microscopy (SEM). Hardness was determined using the Vickers technique and tribological properties were studied by the ball-on-disk method. The coefficient of friction (COF) and specific wear rates were evaluated from tribological tests. Worn surfaces were studied by SEM and confocal microscopy. Interdiffusion transition regions were formed among individual microstructural constituents (Al₂O₃, In, GNPs) under high sintering temperatures, which were responsible for the balanced hardness and low porosity of the produced composites. The addition of In and graphene nanoplatelets resulted in smaller COF and wear rates indicating good improvement in the tribological behavior. The prepared Al₂O₃-5In-2GNP and Al₂O₃-10In-2GNP composites represent promising nanocomposites for self-lubricating applications.