The paper presents a simple and cost-effective way of enhancing the thermal conductivity of the paraffin/graphite phase change material (PCM) composite spheres manufactured by using a low-cost and eco-friendly method. The composite materials were made of an admixture of 5–20% vol. graphite powder. The manufacturing process of macro-encapsulated PCM consists of creating digital models, mold printing, and PCM injections. The experimental data shows that composite materials have an increased thermal conductivity, from 3 to 11 times compared to paraffin, and are effective in cooling application of electronic components where they lowered the maximum temperature up to 30 °C. For low-volume PCM sphere fabrication, it was proposed the injection molding in the 3D printed mold; the results show that fused deposition modeling (FDM) is efficient in saving energy up to 30% compared to machining. The carbon emissions generated during the fabrication technology were found to be strongly dependent on printing process parameters and the energy mix used to produce the electrical energy used.

This paper presents the usage of spark plasma sintering (SPS) as a method to obtain aluminum-expanded perlite syntactic foams with high porosity. In the test samples, fine aluminum powder with flaky shape particles was used as matrix material and natural, inorganic, granular, expanded perlite was used as a space holder to ensure high porosity (35–57%) and uniform structure. SPS was used to consolidate the specimens. The structures were characterized by scanning electron microscopy and compression tests. Energy absorption (W~7.49 MJ/m³) and energy absorption efficiency (EW < 90%) were also determined.

This study introduces a novel approach to zinc sintering, showcasing the remarkable potential of the cold sintering process. This innovative technique enables the compaction of zinc at close to room temperatures through the synergistic application of uniaxial pressure and a solvent. The cold sintering process stands out as an environmentally conscious production method, yielding substantial reductions in both energy consumption and harmful emissions. The present research demonstrates the sintering of zinc powder utilizing its oxide surface layer. Operating within temperatures close to room temperature and applying a pressure of 500 MPa, cold sintering occurred already after a holding time of 5 min. To increase the porosity, diverse NaCl concentrations (<60%) were employed and the size range of 1.25–1.6 mm was selected to improve the salt dissolution. To facilitate the sintering procedure, a strategic inclusion of diluted acetic acid (50%) and ethanol was made. This additive duo effectively facilitated the dispersion of acetic acid throughout the sample matrix. In the cold sintering process, processing parameters including solvent, pressure, temperature and holding time play critical roles in zinc densification.