Surface Engineering and Applied Electrochemistry最新文献

In this paper, an attempt to evaluate the effect of particles on the electrical conductivity of liquid dielectrics is made. For this purpose, a conductivity model is formulated taking into account the presence of relatively large charged microparticles in the dielectric. Based on calculations using the model, a comparative assessment of electrical conductivity was carried out. It is shown that in sufficient quantities, particles can significantly increase the electrical conductivity when forming double electric layers near their surface.

The purpose of this research was to enhance the wear behavior and hardness of cold work D5 tool steel by depositing a TiCrN multilayer nanocoating through the physical vapor deposition with a cathodic arc. A comparison was made between the properties of the applied coatings and the thin-film TiN and CrN nanolayer coatings produced using the same method. Various tests, including micro-hardness tests, surface wear tests, and corrosion examinations using the Tafel test, were conducted. The coating surfaces and the wear lines were analyzed using field emission scanning electron microscopy with energy dispersive X-ray spectroscopy. The results indicated that the TiN thin-film coating, the TiCrN multilayer nanocoating and the CrN coating exhibited higher hardness of 226, 205, and 165 HV, respectively than the less coated sample (101 HV). Additionally, friction coefficients were measured and found to be 0.35, 0.3, and 0.27 for TiN, TiCrN, and CrN coatings, respectively. Furthermore, the corrosion test results demonstrated that the TiCrN multilayer coating exhibited excellent corrosion resistance. The analysis of wear surfaces revealed abrasion wear mechanisms for the TiN and CrN coatings, while fatigue wear mechanisms were observed for the TiCrN coating. Those findings suggest that the TiCrN multilayer nanocoating has potential applications in the production of tool steel pieces, complementary parts, and machine tool components.

The present paper deals with a comprehensive investigation of the wettability of the platinum surface when subjected to water nanodroplets using molecular dynamics simulation. To evaluate the wettability of a solid-liquid interface, the contact angle was analyzed varied with respect to time, temperature, and energy between the atoms and the surfaces using large-scale atomic/molecular massively parallel simulator. It is worth noting here that the research reveals a significant change in the contact angle which goes from a prominent 147.158° to a more favorable 123.65° in an incredibly brief period of 2 to 200 fs. That dynamic change highlights the platinum surface significant improvement in wettability and sheds light on the kinetics of solid-liquid interactions. The result also shows that the ambient temperature reduced from 320 to 285.5 K, and the droplet temperature increased from 2.43 to 170 K in the same temperature range along with a decrease in the total energy. This study emphasizes the progressive aspect of wettability by revealing that, as time increases, the contact angle consistently reduces. This shows the perspective on how the platinum surface becomes increasingly amenable to wetting by H₂O nanodroplets.

The current study was conducted to measure the concentrations of nitrite by a glassy carbon electrode modified with MXene/La³⁺ doped ZnO/hemoglobin (Hb) nanocomposite as a new voltammetric sensor. Chronoamperometry, differential pulse voltammetry, and cyclic voltammetry were employed to characterize the modification of the electrode surface. According to the analytical results, the glassy carbon electrode incorporated with MXene/La³⁺ doped ZnO/Hb nanocomposite was able to detect the presence of different concentrations of nitrite (0.1–700.0 μM), with the detection limit of 4.0 × 10^–8 M. The proposed sensor can be proposed as acceptable electrochemical detector of nitrite in real samples.

Abrasive water jet (AWJ) cutting is an emerging material processing technology with significant advantages, such as no thermal deformation, high processing versatility, high flexibility, and low cutting force. It is used in various applications including machining, cleaning, surface preparation, and material cutting. The main concerns during the AWJ cutting process are the surface roughness and the kerf geometry. This study aimed to successfully predict the surface roughness and the kerf geometry during low pressure AWJ machining to cut metal sheets at low and high water pressures when cutting the stainless steel and copper specimens. The experimental results show that a low water pressure indicates fewer variations between the surface roughness and the kerf angle. At various pressures, the roughness values ranged from 3.087 to 4.817 µm. A regression model was developed to predict the surface roughness and the kerf angle. As a result, the effect of water pressure can only increase the kinetic energy but cannot affect other processing parameters separately. Scanning electron microscopy revealed micro-cracks during the AWJ cutting process.

Based on mathematical modeling of the process of electrohydraulic sheet stamping, the influence of a pressure plate on the deformation of a workpiece rigidly clamped along its outer contour was studied. The influence of the thickness of the pressure plate and its internal diameter, in relation to the diameter of the cavity of the cylindrical discharge chamber, on the energy of plastic deformation of the workpiece and the shape of its deflection; parameters of the pressure plate on the pressure of hydrodynamic waves on the workpiece; and the shape of its deflection and the efficiency of using the energy stored in the capacitor bank for plastic deformation of the workpiece have been established.

The surface plasmon resonance (SPR) of metal nanoparticles (NPs) plays a crucial role in designing numerous chemical and biomolecule sensors. Therefore, in this work, gold (Au) NPs thin films were deposited on a glass substrate at the substrate temperature of 300°C using the pulsed laser deposition method. The effect of the number of laser pulses on the morphology and optical properties of Au NPs was investigated through scanning electron microscopy, ultraviolet-visible spectroscopy, and photoluminescence studies. Scanning electron microscopy revealed that the particle size increased from 14 to 28 nm whereas the inter-particle distance decreased from 19 to 8 nm with an increase of the number of laser pulses from 1000 to 5000, but the thickness of the Au NPs film increased from 107.5 to 132.4 nm. The observance of the SPR peak around 565–586 nm in absorption spectroscopy confirmed the formation of Au NPs. The red shift of the SPR peak position at higher numbers of laser pulses could be attributed to the simultaneous enhancement in the particle size and the reduction of the inter-particle distance. Further, the trend of the full-width half maxima in the intrinsic and extrinsic particle size region was studied, and the phenomena behind the SPR broadening was briefly explained. The photoluminescence spectrum has also shown a strong emission band at 530 nm, with a corresponding energy band gap of 2.34 eV, and the band position was in good agreement with the SPR peak position. This study suggests that the SPR properties of Au NPs can be tuned by varying the number of laser pulses as it strongly affects the morphology of Au NPs.

It has been shown that the response of the functional property of the deposit on the action of dimensional factors of electrolysis conditions equally determines the dimensional property of the electrolyte. It has been established that the most universal assessment methods of dimensional effects can be formed based on the correlation of dimensionless quantities for a number of specified and directional values of the size factor with a number of corresponding values of the functional parameter of the sediment. It is shown that studying the dimensional properties of electrolytes and deposits, depending on the type of dimensional factors and their scale scales, will expand the capabilities of the electrolytes used, increase the controllability of the formation of the functional parameter of the deposit, obtain new information about the process of deposition of nanostructured deposits, and reveal the factors which previously did not attract attention. A determination method and cell for quantifying the dimensional properties of the precipitate and electrolyte are presented.

Research into self-oscillatory processes in semiconductors and semiconductor structures makes it possible to formulate the physical mechanism of these unique phenomena and create solid-state generators and sensors of physical quantities with frequency-amplitude output. It was established that the excitation conditions and parameters of self-oscillations of the current were studied in more detail only in silicon doped with manganese and zinc atoms, as well as in semiconductor compounds CdSe, CdS, InGa and in some structures, while the boundary regions of existence of these current instabilities depending on external factors were not very accurately determined in other materials. This led to the lack of reproducible results and a discrepancy in the correlation between the electrical parameters of the material and the parameters of self-oscillations of the current (amplitude, frequency). In this regard, the results of comprehensive studies of self-oscillations of current in silicon doped with impurity atoms of manganese, zinc, sulfur, and selenium are presented. A physical mechanism of current self-oscillations is proposed, which is in good agreement with the known experimental results obtained.

In this study, new synthesized triazole-containing copolymer derivatives were investigated. The title compounds were identified using Fourier-transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, and carbon-13 nuclear magnetic resonance spectroscopy. The inhibitory effects of the synthesized compounds (1, 2, and 5) on the corrosion of mild steel in a solution containing 0.5 M H₂SO₄ were studied using also the electrochemical polarization technique (Tafel plots). The resulted values of corrosion parameters showed the efficacy of corrosion inhibition by raising the concentration of organic corrosion inhibitors of mild steel in 0.5 M H₂SO₄ solution at 295 K.