This paper presents sustainable technology for environmentally friendly composite production. Biobased unsaturated polyester resin (b-UPR), synthesized from waste polyethylene terephthalate (PET) glycosylate and renewable origin maleic anhydride (MAnh) and propylene glycol (PG), was reinforced with unmodified and vinyl-modified biosilica nanoparticles obtained from rice husk. The structural and morphological properties of the obtained particles, b-UPR, as well as composites, were characterized by Fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) techniques. The study of the influence of biosilica modification on the mechanical properties of composites was supported by hardness modeling. Improvement of the tensile strength of the b-UPR-based composite at 2.5 wt.% addition of biosilica modified with vinyl silane, named “b-UPR/SiO₂-V” composite, has been achieved with 88% increase. The thermal aging process applied to the b-UPR/SiO₂-V composite, which simulates use over the product’s lifetime, leads to the deterioration of composites that were used as fillers in commercial unsaturated polyester resin (c-UPR). The grinded artificially aged b-UPR composites were used as filler in c-UPR for the production of a table top layer with outstanding mechanical properties, i.e., impact resistance and microhardness, as well as fire resistance rated in the V-0 category according to the UL-94 test. Developing sustainable composites that are chemically synthesized from renewable sources is important from the aspect of preserving the environment and existing resources as well as the extending their life cycle.

Copper electrodeposition on (111)-oriented Si substrate was performed by the pulsating current (PC) regime at various average current densities in the range of 15–70 mA·cm⁻², obtained by varying either the frequency (30, 50, 80 and 100 Hz for the current density amplitude of 100 mA·cm⁻²) or the current density amplitude (120 and 140 mA·cm⁻² at 100 Hz). The produced Cu coatings were examined by SEM, AFM and XRD techniques. The morphology of the coatings changed from those with large grains to fine-grained and globular, while the crystal structure changed from the strong (220) to the strong (111) preferred orientation by increasing the average current density. The mechanical characteristics of coatings were examined using Vickers micro-indentation tests, applying the Chicot–Lesage (C–L) composite hardness model for the analysis of microhardness. The maximum microhardness was obtained for the Cu coating produced at an average current density of 50 mA·cm⁻², with a current density amplitude of 100 mA·cm⁻² and a frequency of 100 Hz. This copper coating was fine-grained and showed the smallest roughness in relation to the other coatings, and it was obtained in the mixed activation–diffusion control between the end of the effect of the activation control and the beginning of the dominant effect of diffusion control.

Correlation among morphological, structural and hardness characteristics of electrodeposited copper coatings is presented in this review paper. Cu coatings were produced applying constant galvanostatic (DC) and pulsating current (PC) regimes on hard silicon (Si(111)) and brass substrates. The parameters of the electrochemical deposition were analyzed, which include the kinds of electrolyte and cathode, the coating thickness and the electrolyte stirring, as well as the parameters defining PC regime, such as the average current density and the current density amplitude, were analyzed. Morphology and structure of Cu coatings were examined by scanning electron microscope (SEM), atomic force microscope (AFM) and by X-ray diffraction (XRD), while hardness was examined by Vickers microindentation. The coatings of Cu on both Si(111) and brass cathodes belong to “soft film (coating) on hard substrate” composite hardness system, and the Chicot–Lesage (C–L) composite hardness model was applied to estimate a hardness of the Cu coatings. Analyzing the examined parameters and regimes of electrodeposition, the critical relative indentation depth (RID)_c of 0.14 has been defined by the C–L model. Based on done analyses, it is shown that this RID value, separating a zone where measured hardness corresponds to the coating hardness and a zone where it is necessary to apply the C–L model to determine an absolute hardness of the Cu coatings, has an universal character for the electrolytically produced Cu coatings on Si(111) and brass substrates.

The mechanical characteristics of electrochemically deposited copper coatings have been examined by application of two hardness composite models: the Chicot-Lesage (C-L) and the Cheng-Gao (C-G) models. The 10, 20, 40 and 60 µm thick fine-grained Cu coatings were electrodeposited on the brass by the regime of pulsating current (PC) at an average current density of 50 mA cm⁻², and were characterized by scanning electron (SEM), atomic force (AFM) and optical (OM) microscopes. By application of the C-L model we determined a limiting relative indentation depth (RID) value that separates the area of the coating hardness from that with a strong effect of the substrate on the measured composite hardness. The coating hardness values in the 0.9418–1.1399 GPa range, obtained by the C-G model, confirmed the assumption that the Cu coatings on the brass belongs to the “soft film on hard substrate” composite hardness system. The obtained stress exponents in the 4.35–7.69 range at an applied load of 0.49 N indicated that the dominant creep mechanism is the dislocation creep and the dislocation climb. The obtained mechanical characteristics were compared with those recently obtained on the Si(111) substrate, and the effects of substrate characteristics such as hardness and roughness on the mechanical characteristics of the electrodeposited Cu coatings were discussed and explained.

Rice husk was used to produce silica particles, which were then used to reinforce the polymer matrix. The synthesized SiO2 particles were characterized using X-ray diffraction, Fourier transforms infrared spectroscopy (FTIR) and scanning electron microscopy with EDS. In a PMMA matrix, prepared SiO2 particles in amounts of 1, 3, and 5 wt.% were used as reinforcing agents. The goal of this research was to see if SiO2 particles had any effect on the mechanical properties of polymer composite materials. The morphology of the composites was examined using a field emission scanning electron microscope (FE-SEM). Vickers microindentation hardness and impact testing were used to determine the mechanical properties of the obtained composites. The indentation creep?s behavior of a polymethylmetacrylate (PMMA) composite material with varying amounts of nanoparticles (SiO2) was investigated and analyzed.

Mechanical (hardness and adhesion) and electrical (sheet resistance) characteristics of electrolytically produced copper coatings have been investigated. Morphologies of Cu coatings produced galvanostatically at two current densities from the basic sulfate electrolyte and from an electrolyte containing levelling/brightening additives without and with application of ultrasound for the electrolyte stirring were characterized by SEM and AFM techniques. Mechanical characteristics were examined by Vickers microindentation using the Chen–Gao (C–G) composite hardness model, while electrical characteristics were examined by the four-point probe method. Application of ultrasound achieved benefits on both hardness and adhesion of the Cu coatings, thereby the use of both the larger current density and additive-free electrolyte improved these mechanical characteristics. The hardness of Cu coatings calculated according to the C–G model was in the 1.1844–1.2303 GPa range for fine-grained Cu coatings obtained from the sulfate electrolyte and in the 0.8572–1.1507 GPa range for smooth Cu coatings obtained from the electrolyte with additives. Analysis of the electrical characteristics of Cu coatings after an aging period of 4 years showed differences in the sheet resistance between the top and the bottom sides of the coating, which is attributed to the formation of a thin oxide layer on the coating surface area.