Ioana Ion

Silver (Ag)-based conductive coatings are widely used in electrical contacts due to their excellent electrical conductivity, low contact resistance, good thermal stability and oxidation resistance, although their susceptibility to sulfidation and environmental corrosion is a concern under certain service conditions. In recent years, significant progress has been achieved in both the manufacture and performance optimization of Ag-based coatings to satisfy the demanding requirements of modern electrical and electronic systems. This review summarizes recent advances in fabrication techniques and processing parameters for Ag-based coatings, including electroplating, electroless deposition, magnetron sputtering, electrospark deposition, thermal spraying, and electrical explosion spraying on metallic substrates, particularly on copper and steel substrates. More attention is given to microstructural design strategies, such as the incorporation and homogeneous dispersion of reinforcement or solid lubricant phases within the Ag matrix, to enhance contact reliability and operational endurance. The performance of Ag-based coatings is analyzed in terms of their physical, chemical and mechanical properties, electrical contact resistance, friction and wear behavior, arc erosion resistance, and environmental durability under different service conditions. Key challenges, including coating degradation under high electrical loads, mechanical wear, and corrosive environments, are highlighted. Future research directions are outlined, focusing on multifunctional coating structures that enhance surface performance and ensure the long-term durability of electrical contacts.

Silver (Ag)-based conductive coatings are widely used in electrical contacts due to their excellent electrical conductivity, low contact resistance, good thermal stability and oxidation resistance, although their susceptibility to sulfidation and environmental corrosion is a concern under certain service conditions. In recent years, significant progress has been achieved in both the manufacture and performance optimization of Ag-based coatings to satisfy the demanding requirements of modern electrical and electronic systems. This review summarizes recent advances in fabrication techniques and processing parameters for Ag-based coatings, including electroplating, electroless deposition, magnetron sputtering, electrospark deposition, thermal spraying, and electrical explosion spraying on metallic substrates, particularly on copper and steel substrates. More attention is given to microstructural design strategies, such as the incorporation and homogeneous dispersion of reinforcement or solid lubricant phases within the Ag matrix, to enhance contact reliability and operational endurance. The performance of Ag-based coatings is analyzed in terms of their physical, chemical and mechanical properties, electrical contact resistance, friction and wear behavior, arc erosion resistance, and environmental durability under different service conditions. Key challenges, including coating degradation under high electrical loads, mechanical wear, and corrosive environments, are highlighted. Future research directions are outlined, focusing on multifunctional coating structures that enhance surface performance and ensure the long-term durability of electrical contacts.

This study focuses on the development and characterization of biodegradable polymer composites consisting of a polypropylene (PP) matrix, carbon black pigment, and hybrid fillers. The fillers incorporated into these composites consisted of a blend of fibers and particles derived from natural, biodegradable materials, such as flax fibers (FFs) and wood flour (WF) particles. The compositions of polymer material were expressed as PP/FF/WF weight ratios of 100/0/0, 70/5/25, and 70/10/20. The polymer materials were prepared using conventional plastic processing methods like extrusion to produce composite mixtures, followed by melt injection to manufacture the samples needed for characterization. The structural characterization of the polymer materials was conducted using optical microscopy and X-ray diffraction (XRD) analyses, while thermal, mechanical, and dielectric properties were also evaluated. Additionally, their biodegradation behavior under mold exposure was assessed over six months. The results were analyzed comparatively, and the optimal composition was identified as the polymer composite containing the highest flax fiber content, namely PP + 10 wt.% flax fiber + 20 wt.% wood flour.

This study focuses on the development and characterization of biodegradable polymer composite materials with a polypropylene (PP) matrix and hybrid fillers. The fillers incorporated into these composites consisted of a blend of fibers and particles derived from natural, biodegradable materials, such as flax fibers (FF) and wood flour (WF) particles. The compositions of polymer material were expressed as PP/FF/WF weight ratios of 100/0/0, 70/5/25, and 70/10/20. The polymer materials were prepared using conventional plastic processing methods like extrusion to produce composite mixtures, followed by melt injection to manufacture the samples needed for characterization. The structural characterization of the polymer materials was conducted using optical microscopy and X-ray diffraction (XRD) analyses, while thermal, mechanical, and dielectric properties were also evaluated. Additionally, their biodegradation behavior under mould exposure was assessed over six months. The results were analyzed comparatively, and the optimal composition was identified as the polymer composite containing the highest flax fiber content, namely PP + 10% flax fiber + 20% wood flour.

This study focuses on synthesizing a hybrid micro-hydrogel with antibacterial properties by electron beam irradiation. The micro-hydrogel matrix is based on biocompatible polymer poly(vinyl)alcohol functionalized with antibacterial compounds: graphene oxide and silver nanoparticles The polymer composites were synthesized by irradiation with an electron beam at 10, 25, 50 kGy absorbed dose to form silver nanoparticles.

Three types of dry polarizable electric bioimpedance sensor for skin bioimpedance monitoring without skin preparation have been developed. The sensitive materials as a component of these sensors are the conductive polypyrrole and hybrid nanocomposite polypyrrole-Ag, with 10% and 20% Ag incorporated in the polypyrrole matrix. The hybrid nanocomposites Ag nanoparticles (NPs)/polypyrrole were obtained by introducing the colloid solution of Ag NPs in pyrrole solution, followed by polymerisation, and calculated for 10% and 20% of monomer’s mass. The structural characterisation and morphological analysis of these sensitive materials were carried-out by Raman spectrometry, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. In making the electrodes, the technique of pressing powders of polypyrrole and hybrid composites Ag NPs/polypyrrole in a hydraulic press was used in the form of a disk. The electric bioimpedance performance of sensors was investigated using a two-point method in the frequency range of 1–300 kHz, at a voltage of 2 V_peak-peak, on six human subjects, three men and three women. For these three bioimpedance sensors, it was found that the electric bioimpedance of the skin decreases across the frequency range and shows good linearity of the impedance-frequency curve on the range frequency of interest in bioimpedance measurements.

Radiochemical synthesis of metallic nanoparticles is an eco-friendly method allowing the obtaining of controlled size, well dispersed and highly stable particles at very mild conditions. Colloidal silver nanoparticles were synthesized in a one-step process, in an aqueous system consisting of polyvinyl alcohol (PVA)/Ag+/isopropyl alcohol (IPA), irradiated at various doses by using high energy ionizing radiations (g-rays). The UV-Vis spectra have shown a maximum absorption peak in the range of 390-450 nm, specific for silver nanoparticles. The size of the obtained spherical shape nanoparticles was below 50 nm and decreased with increasing of the irradiation dose.

The objective of the work presented in this paper is the obtaining of non-woven fabrics to be used as filtering membranes. These fabrics were produced from expanded polystyrene (EPS) and β-cyclodextrin (β-CD) solutions in dimethylformamide (DMF) using an electrospinning unit with a copper plate collector. The influence of the processing parameters and the percentage of β-cyclodextrin added to expanded polystyrene were investigated.