The article considers issues related to improving the surface characteristics of titanium Gr2 using one of the lightest, cheapest and most ecological methods—electrospark deposition with low pulse energy and with ultradisperse electrodes TiB₂-TiAl with nanosized additives of NbC and ZrO₂. Using profilometric, metallographic, XRD, SEM and EDS methods, the change in the geometric characteristics, composition, structure, micro and nanohardness of the coatings as a function of the electrical parameters of the ESD regime has been studied. The results show that the use of TiB₂-TiAl electrodes and low pulse energy allows the formation of dense, continuous and uniform coatings that demonstrate a significant reduction in roughness, inherent irregularities and structural defects of electrospark coatings. Coatings with minimal defects, with crystalline–amorphous structures, with newly formed intermetallic and wear-resistant double and triple phases of the type AlTi₃, TiAl₃, TiB, TiN_0.3, Al₂O₃, AlB₂, TiC_0.3N_0.7, Ti_3.2B_1.6N_2.4, Al_2.86O_3.45N_0.55 have been obtained. Possibilities have been found for controlling and obtaining specific values for the roughness and thickness of coatings in the ranges Ra = 1.5–3.2 µm and δ = 8–19.5 µm, respectively. The electrical parameters of the modes ensure the production of coatings with previously known thickness and roughness, with increased microhardness up to 13 GPa, with the maximum possible content of deliberately synthesized high-hard phases and with ultra-fine-grained structures have been defined.

This study examines how the frequency of an innovative energy harvester is tuned and how it behaves. This harvester transforms thermal energy into mechanical oscillations of two polyvinylidene fluoride (PVDF) piezoelectric beams, which produce electrical energy via a shape memory alloy (SMA) thread. The oscillation frequency is modified by two magnetic weights that are positioned symmetrically on the SMA thread and interact with stationary NdFeB permanent magnets. The SMA thread shifts laterally due to longitudinal thermal contraction and expansion induced by a constant-temperature heater. Temperature gradients above the heater trigger cyclical variations in the length of the SMA thread, leading to autonomous vibrations of the masses in both the vertical and horizontal planes. An experimental apparatus was constructed to analyze the harvester by tracking the motions of the masses and the voltages produced by the piezoelectric beams. Information was gathered regarding the correlation between output voltage and power with the consumer’s load resistance. These outcomes were confirmed using a multiphysics dynamic simulation that incorporated the interconnections among mechanical, thermal, magnetic, and electrical systems. The findings indicate that the use of permanent magnets increases the bending vibration frequency from 8.3 Hz to 9.2 Hz. For a heater maintained at 70 °C, this boosts the output power from 1.9 µW to 8.18 µW. A notable property of the considered energy harvester configuration is its ability to operate at cryogenic temperatures.

The tribological and corrosion behavior of commercial pure titanium - Ti-Gr2 with coatings obtained by mechanized contactless local electrospark deposition (LESD) with a rotating electrode with low pulse energy and an ultradisperse TiB2-TiAl electrode reinforced with ZrO2 and NbC nanoparticles is investigated in this work. The current research is driven by the need for improved corrosion resistance of titanium surfaces in automotive components, shipbuilding, aviation, aerospace, petrochemical and many other industrial and domestic areas. The work is a continuation of our previous research, in which the correlations between the electrical parameters of the LESD mode and the relief, roughness, thickness, microhardness, composition and structure of the coatings obtained with this electrode were studied and analyzed. In this work, the influence of the pulse parameters of the LESD process (respectively, the roughness, thickness, composition, structure of the coatings) on the coefficient of friction, abrasive and corrosion resistance of the coatings has been studied and their role in simultaneous protection of titanium surfaces from wear and corrosion has been clarified. Coatings with the presence of newly formed wear-resistant phases and crystalline-amorphous structures, with increased hardness up to 13 GPa, low roughness Ra= 1.5 -2.8 μm, thickness up to 20 μm and minimal structural defects have been formed. By comparing the potentiodynamic polarization curves, polarization resistance, electrochemical impedance and tribological characteristics of the coated surfaces, it has been established that their corrosion resistance increases by more than 2 times and their wear resistance during friction increases by 4-5 times compared to those of the substrate. Appropriate pulse parameters have been defined to allow for uniform coatings with reduced roughness and structural defects, with predictable thickness, roughness and hardness, and with maximized corrosion and abrasive wear resistance.

This paper discusses the frequency tuning and dynamics of a novel energy harvester that converts thermal energy into mechanical vibrations of two polyvinylidene fluoride (PVDF) piezoelectric cantilevers that generate electrical energy through a shape memory alloy (SMA) filament. The vibration frequency is tuned by two ferromagnetic masses symmetrically arranged on the SMA filament and interacting with fixed NdFeB permanent magnets. The SMA filament moves transversely due to its own longitudinal temperature contractions and stretches due to a constant temperature heater. Temperature differences above the heater cause periodic changes in the length of the SMA filament, resulting in self-excited oscillations of the masses in the vertical and horizontal directions. An experimental setup was created to study the harvester by measuring the mass displacements and electrical voltages generated by the piezoelectric cantilevers. Data on the dependence of the output voltage and power on the load resistance of the consumer were obtained. The experimental results have been validated by a multiphysical dynamic model that considers the relationships between the mechanical, thermal, magnetic and electrical domains. Research shows that permanent magnets increase the frequency of bending vibrations from 8.3 Hz to 9.2 Hz. which for a heater with a constant temperature of 70 °C, increases the output power from 1.9 µW to 8.18 µW. A special feature of the proposed energy harvester design is the ability to operate at cryogenic temperatures.

In this work, the tribological and corrosion behavior of commercially pure titanium—Ti-Gr2 with coatings obtained by mechanized contactless local electrospark deposition (LESD) with low pulse energy and a rotating electrode of TiB₂-TiAl reinforced with ZrO₂ and NbC nanoparticles was investigated. The current research is driven by the need for improved corrosion and abrasion resistance of titanium surfaces in automotive components, shipbuilding, aerospace, petrochemical and many other industrial and domestic areas. This work is a continuation of our previous study, in which the dependences of the relief, roughness, thickness, microhardness, composition and structure of the coatings obtained with this electrode on the electrical parameters of the LESD mode were studied and analyzed. In this work, the influence of the pulse parameters of the LESD process (respectively, roughness, thickness, composition and structure of the coatings) on the tribological and corrosion characteristics of the coatings has been investigated and the possibility of simultaneous protection of titanium surfaces from wear and corrosion has been demonstrated. Coatings containing nanocrystalline and amorphous-like structures have been formed, with synthesized new compounds and phases, and with increased hardness up to 13 GPa, low roughness Ra = 1.5–3 μm, thickness 8–20 μm and minimal structural defects. By comparing the potentiodynamic polarization curves, polarization resistance, electrochemical impedance and tribological characteristics of the coated surfaces, it has been established that their corrosion resistance increases by more than 1–2 orders of magnitude and their wear resistance during friction increases by 4–5 times compared to those of the substrate. Appropriate values of the electrical parameters of the LESD mode are presented, which allow obtaining uniform coatings with reduced roughness and structural defects, with predictable thickness, roughness and hardness, and with maximized corrosion and abrasive wear resistance to allow for uniform coatings with reduced roughness and structural defects, with predictable thickness, roughness and hardness, and with maximized corrosion and abrasive wear resistance.

The article considers issues related to improving the surface characteristics of titanium Gr2 using one of the lightest, cheapest and ecological methods - electrospark deposition (ESD) with low pulse energy and with ultradisperse electrodes TiB2-TiAl with nanosized additives of NbC and ZrO2. By means of profilometric, metallographic, XRD, SEM and EDS methods, the change in the geometric characteristics, composition, structure, micro- and nanohardness of the coatings as a function of the electrical parameters of the ESD regime has been studied. The results show that the use of TiB2-TiAl electrodes and low pulse energy allows the formation of dense, continuous and uniform coatings, demonstrating a significant reduction in roughness and inherent irregularities and structural defects of electrospark coatings, as well as the synthesis of newly formed wear-resistant phases and amorphous-nanocrystalline structures. The obtained coatings have crystal-line-amorphous structures, with newly formed intermetallic and wear-resistant phases with minimal defects, with roughness, thickness and microhardness, which can be controlled within the ranges Ra =1.8-3.5 µm, δ= 8-20 µm, HV=9-13 GPa, respectively. Energy pulse parameters have been defined to produce of coatings with a predetermined thickness and roughness, maximum increased hardness and with the most favorable characteristics in terms of abrasive and corrosion resistance.