Search Results (12)

In this study, the drilling of an Al 6082-T6 alloy and the effects of cutting tool coating and cutting parameters on surface roughness, cutting temperature, hole diameter, circularity, and cylindrical variations was investigated. In addition, the prediction accuracy of Taguchi, artificial neural networks (ANNs), and adaptive neuro-fuzzy inference system (ANFIS) methods was compared using both experimental results and Signal/Noise (S/N) ratios derived from the experimental results. The experimental design was prepared according to Taguchi L27 orthogonal indexing. As a result, it was observed that increasing the cutting speed and feed rate increases the cutting temperature hole error, circularity error and cylindricity error. Increasing the cutting speed positively affected the surface roughness, while increasing the feed rate led to an increase in the surface roughness. The lowest surface roughness, cutting temperature, hole diameter error and hole circularity error values were measured for the uncoated cutting tool. The minimum cylindricity variation was measured for drilling with TiAlN-coated cutting tools. The optimum cutting parameters were A1B1C3 (Uncoated, 0.11 mm/rev, 200 m/min) for surface roughness, A1B1C1 (Uncoated, 0.11 mm/rev, 120 m/min) for cutting temperature, hole error, circularity error and cylindricity error. In the estimation of the output parameters with Taguchi, ANNs and ANFIS, it was observed that the estimates made by converting the experimental values into S/N ratios were more accurate than the estimates made with the experimental results. The reliability coefficient and prediction ability of the ANN model were found to be higher than Taguchi and ANFIS models in estimating the output parameters. Full article

Due to its excellent specific strength, corrosion resistance, and biocompatibility, titanium alloy is often used as a biological implant material. In order to address the issues of low hardness and poor wear resistance of the Ti-25Nb-3Zr-2Sn-3Mo titanium alloy, a TiN/Sn coating with good biocompatibility was deposited on its surface using a new composite modification technology of surface mechanical strengthening + surface mechanical coating. By taking advantage of the wear resistance of TiN and the adhesiveness of Sn, a composite coating with corrosion–wear resistance was formed to improve its corrosion–wear resistance. Using TiN/Sn powders of different ratios (10% Sn, 20% Sn, 30% Sn, and 40% Sn) as media, the alloy was subjected to a combined strengthening treatment of surface mechanical attrition and solid-phase coating under a nitrogen atmosphere. The microstructure and mechanical properties of the composite-strengthened layer were tested by means of XRD, SEM-EDS, a nanoindentation tester, a white-light interferometer, and a reciprocating wear tester. Moreover, the corrosion–wear properties of the samples under different loads and electrochemical conditions were analyzed. The results show that the surface composite-strengthened layer of the alloy consisted of a TiN/Sn coating + a mechanical deformed layer. With an increase in the Sn content, the thickness of the TiN/Sn coating continuously increased, while the thickness of the mechanical deformed layer continuously decreased. The composite-strengthened layer had good comprehensive mechanical properties. In the SBF solution, the corrosion–wear resistance of the composite-strengthened samples improved; the degree of wear first decreased and then increased with the increase in the Sn content, and it reached the optimal value when the Sn content was 30%. Compared with the raw sample, the corrosion of the coating sample increased, but the wear significantly decreased. The corrosion–wear synergy factor κ value first increased and then decreased with the increase in the Sn content, reaching a maximum value at the 20% Sn content. This is the result of the combined effect of the corrosion resistance and wear resistance of the coating. Full article

This paper analyzes the surface quality characteristics, such as arithmetic average roughness (Ra), maximum peak-to-valley height (Rt), and average peak-to-valley height (Rz), in hard turning of AISI 52100 steel using a (TiN/TiCN/Al₂O₃) coated carbide insert under a minimal cutting fluid environment (MCFA). MCFA, a sustainable high-velocity pulsed jet technique, reduces harmful effects on human health and the environment while improving machining performance. Taguchi’s L27 orthogonal array was used to conduct the experiments. The findings showed that surface roughness increases with feed rate, identified as the most influential parameter, while the depth of cut shows a negligible effect. The main effects plot of signal-to-noise (S/N) ratios for the combined response of Ra, Rt, and Rz revealed the optimal cutting conditions: cutting speed of 140 m/min, feed rate of 0.05 mm/rev, and depth of cut of 0.3 mm. Feed rate ranked highest in influence, followed by cutting speed and depth of cut. The lower values of surface roughness parameters were observed in the ranges of Ra ≈ 0.248–0.309 µm, Rt ≈ 2.013–2.186 µm, and Rz ≈ 1.566 µm at a feed rate of 0.05–0.07 mm/rev. MCFA-assisted hard turning reduces surface roughness by 35–40% compared to dry hard turning and 10% to 24% when compared to the MQL technique. Moreover, this study emphasizes the significant environmental benefits of MCFA, as it incorporates minimal eco-friendly cutting fluids that minimize ecological impact while enhancing surface finish. Full article

The influence of Cr-Al-Si-N, DLC-Si, and Cr-Al-Si-N/DLC-Si thin coatings deposited on titanium alloy (Ti-Al-Zr-Sn-Nb system) samples with different surface reliefs on wear resistance under abrasion and fretting conditions was investigated. The influence of coatings on the initial microrelief after finishing milling and lapping with micro-grained abrasive was studied by profilometry. The Martens hardness (H) and the elastic modulus (E) were determined through nanoindentation. The H/E ratio was 0.08, 0.09, and 0.13, respectively. The adhesion bond strength and H/E ratio relationship was revealed using a scratch testing analysis. Volumetric wear after 20 min of abrasive exposure was reduced by 11, 25, and 31 times for Cr-Al-Si-N, DLC-Si, and Cr-Al-Si-N/DLC-Si coatings compared to uncoated ones after milling and by 15, 32, and 35 times after lapping. Volumetric wear under fretting conditions was reduced by 1.8 and 4 times for Cr-Al-Si-N coating after milling and lapping. It was reduced by tens of times for DLC-Si coating and by hundreds of times for Cr-Al-Si-N/DLC-Si coating. The Cr-Al-Si-N/DLC-Si coating (a thickness of 3.1 ± 0.15/2.0 ± 0.1 µm) is characterized by the best combination of hardness (24 ± 1 GPa), elastic modulus (185 ± 8 GPa), and friction coefficient (0.04–0.05 after milling and 0.1 after lapping) and ensures maximum wear resistance under a wide range of loads. The novelty of the work is that those coatings were not practically under study concerning the deposition on the titanium alloy regarding typical mechanical loads such as abrasive and fretting wear but are of interest to the aviation and aerospace industry. Full article

D-2-hydroxyglutaric acid (D2HG) is overproduced as a result of the D-2-hydroxyglutaric aciduria and relevant cancers, caused by gene mutation. Accurate analysis of D2HG could help rapid diagnosis of these diseases and allow for timely treatment. In this work, a D-2-hydroxyglutarate dehydrogenase from Ralstonia solanacearum (RsD2HGDH) is cloned and recombinantly expressed. This enzyme features the direct electron transfer to chemical electron mediators (such as methylene blue (MB)) in the absence of additional coenzymes. Therefore, NAD⁺, a natural electron acceptor for the commercial D2HGDH and usually known for being unstable and difficult for immobilization can be avoided in the preparation of biosensors. The RsD2HGDH and MB are co-immobilized on a two-dimensional material, Ti₃C₂ MXene, followed by drop-coating on the gold screen-printed electrode (AuSPE) to construct a compact and portable biosensor. The D2HG in samples can be catalyzed by RsD2HGDH, where the current change is measured by chronoamperometry at −0.23 V. The biosensor shows a D2HG detection range of 0.5 to 120 µM (R² = 0.9974) with a sensitivity of 22.26 μA mM⁻¹ cm⁻² and a detection limit of 0.1 µM (S/N = 3). The biosensor retains 72.52% performance of its incipient state after 30 days of storage. The samples of D2HG-containing fetal bovine serum and artificial urine were analyzed with the recovery of 99.56% to 106.83% and 97.30% to 102.47% further indicating the great application potential of our portable D2HG biosensor. Full article

In order to improve the wear and corrosion resistance of micro-arc oxidation (MAO) coating on a Ti-5Al-1V-1Sn-1Zr-0.8Mo alloy, 0–0.20 g/L graphene was added to the electrolyte to prepare micro-arc oxidation coating. The thickness, roughness, micro-morphology, and composition of the MAO coating were characterized, and the wear and corrosion resistance of the coating was tested and analyzed. The results show that with 0.05 g/L of graphene in the electrolyte, the roughness of the coating decreased from 56.76 μm to 31.81 μm. With the increase in the addition of graphene, the microstructure of the coating became more compact, the diameter of micro-holes and micro-cracks decreased, and the corrosion resistance of the coating improved. The wear tests showed that the mass loss of the coating at the early wear stage (0~100 revolutions) was greater than that at the later stage (100~250 revolutions), and the wear resistance of the coating obtained by the addition of 0.10 g/L of graphene was the highest. With 0.10 g/L of graphene, the adhesion force between the coating and the substrate alloy is the largest, reaching 57.1 N, which is 9.98 N higher than that without graphene. After salt spray corrosion for 480 h, the coating with graphene has better corrosion resistance than that of a graphene-free coating. Full article

A novel titanium dioxide nanotube (TiO₂NTS) coated fiber for solid-phase microextraction (SPME) was prepared by in situ anodization of titanium wire in electrolyte containing ethylene glycol and ammonium fluoride (NH₄F). The effects of different electrolyte solutions (NH₄F and ethylene glycol) and oxidation voltages on the formation and size of TiO₂NTs was studied. It was obtained from the experiment that TiO₂NTs arrays were arranged with a wall thickness of 25 nm and the diameter of 100 nm pores in ethylene glycol and water (v/v, 1:1) containing NH₄F of 0.5% (w/v) with a voltage of 20 V at 25 °C for 30 min. The TiO₂NTs were used as solid-phase microextraction fiber coatings coupled with high-performance liquid chromatography (HPLC) in sensitive determination of polycyclic aromatic hydrocarbons (PAHs) in spiked real samples water. Under the optimized SPME conditions, the calibration curve has good linearity in the range of 0.20–500 μg·L⁻¹, and the correlation coefficient (R²) is between 0.9980 and 0.9991. Relative standard deviations (RSDs) of 3.5–4.7% (n = 5) for single fiber repeatability and of 5.2% to 7.9% for fiber-to-fiber reproducibility (n = 3) was obtained. The limits of detection (LOD) (S/N = 3) and limits of quantification (LOQ) (S/N = 10) of PAHs were 0.03–0.05 µg·L⁻¹ and 0.12–0.18 µg·L⁻¹. The developed method was applied to the preconcentration and determination of trace PAHs in spiked real samples of water with good recoveries from 78.6% to 119% and RSDs from 4.3 to 8.9%, respectively. Full article

This work is a comprehensive review of sensing materials, which interact with several target gases pertinent to agricultural monitoring applications. Sensing materials which interact with carbon dioxide, water vapor (relative humidity), hydrogen sulfide, ethylene and ethanol are the focus of this work. Performance characteristics such as dynamic range, recovery time, operating temperature, long-term stability and method of deposition are discussed to determine the commercial viability of the sensing materials considered in this work. In addition to the sensing materials, deposition methods are considered to obtain the desired sensing material thickness based on the sensor’s mechanism of operation. Various material classes including metal oxides, conductive polymers and carbon allotropes are included in this review. By implementing multiple sensing materials to detect a single target analyte, the issue of selectivity due to cross sensitivity can be mitigated. For this reason, where possible, it is desirable to utilize more than one sensing material to monitor a single target gas. Among those considered in this work, it is observed that PEDOT PSS/graphene and TiO${}_2$-coated g-C${}_3$N${}_4$ NS are best suited for CO${}_2$ detection, given their wide dynamic range and modest operating temperature. To monitor the presence of ethylene, BMIM-NTf${}_2$, SWCNTs and PtTiO${}_2$ offer a dynamic range most suitable for the application and require no active heating. Due to the wide dynamic range offered by SiO${}_2$/Si nanowires, this material is best suited for the detection of ethanol; a gas artificially introduced to prolong the shelf life of the harvested crop. Finally, among all other sensing materials investigated, it observed that both SWCNTs and CNTs/SnO${}_2$/CuO are most suitable for H${}_2$S detection in the given application. Full article

The formation process of surface coatings fabricated with laser cladding is very complicated and coating quality is closely related to laser cladding process parameters. Generally, the optimization and control of process parameters play key roles when preparing high-quality ceramic coating. In this paper, three reasonable parameters were selected for each process parameter based on the preliminary experiment. The experiment of Ti(C, N) ceramic coating prepared with laser cladding was designed via the Taguchi method. The laser power, spot diameter, overlapping ratio, and scanning velocity were selected as the main process parameters, and their effects on coating micro-hardness were analyzed using the signal-to-noise (S/N) ratio and analysis of variance (ANOVA). Then, based on the back-propagation neural network (BPNN) and quantum-behaved particle swarm optimization (QPSO) algorithm, we created the prediction model of BPNN-QPSO neural network for laser cladding Ti(C, N) ceramic coating. The mapping of process parameters to the micro-hardness of the coating was obtained according to the model and we analyzed the influence of process parameters that interacted with the coating’s micro-hardness. The results showed that the interaction of laser cladding process parameters had a significant effect on the micro-hardness of the coating. The established BPNN-QPSO neural network model was able to map the relationship between laser cladding process parameters and coating micro-hardness. The process parameters optimized by this model had similar results with ANOVA. This research provides guidance for the selection and control of ceramic coating process parameters Ti(C, N) prepared via laser cladding. Full article

Direct current electrodeposited Sn–Ni/TiO₂ nanostructured coatings were produced by embedding two different doped types of TiO₂ particles within the alloy matrix, a commercially available doped carbon-based and doped N,S-TiO₂ particles. The structural characteristics of the composite coatings have been correlated with the effect of loading, type of particles in the electrolytic bath, and the applied current density. Regardless of the type of doped particles TiO₂, increasing values of applied current density resulted in a reduction of the co-deposition percentage of TiO₂ particles and an increase of Tin content into the alloy matrix. The application of low current density values accompanied by a high load of particles in the bath led to the highest codeposition percentage (~3.25 wt.%) achieved in the case of embedding N,S-TiO₂ particles. X-ray diffraction data demonstrated that in composite coatings the incorporation of the different types of TiO₂ particles in the alloy metal matrix modified significantly the nano-crystalline structure in comparison with the pure coatings. The best photocatalytic behavior under visible irradiation was revealed for the composite coatings with the highest co-deposition percentage of doped N,S-TiO₂ particles, that also exhibited enhanced wear resistance and slightly reduced microhardness compared to pure ones. Full article

Planar perovskite solar cells were fabricated on F-doped SnO₂ (FTO) coated glass substrates, with 4,4’-((1E,1’E)-((1,2,4-thiadiazole-3,5-diyl)bis(azaneylylidene))bis(methaneylylidene))bis(N,N-di-p-tolylaniline) (bTAThDaz) as hole transport material. This imine was synthesized in one step reaction, starting from commercially available and relatively inexpensive reagents. Electrochemical, optical, electrical, thermal and structural studies including thermal images and current-voltage measurements of the full solar cell devices characterize the imine in details. HOMO-LUMO of bTAThDaz were investigated by cyclic voltammetry (CV) and energy-resolved electrochemical impedance spectroscopy (ER-EIS) and were found at −5.19 eV and −2.52 eV (CV) and at −5.5 eV and −2.3 eV (ER-EIS). The imine exhibited 5% weight loss at 156 °C. The electrical behavior and photovoltaic performance of the perovskite solar cell was examined for FTO/TiO₂/perovskite/bTAThDaz/Ag device architecture. Constructed devices exhibited good time and air stability together with quite small effect of hysteresis. The observed solar conversion efficiency was 14.4%. Full article

In this paper, the effect of residual stress on the stress–life (S–N) curve and fracture morphology characteristics of Ti6Al4V titanium alloy after laser shock peening (LSP) without protective coating was experimentally investigated. The fatigue test and residual stress measurement were conducted on specimens before and after the LSP process. It was shown that LSP produced a high-amplitude compressive residual stress field on the surface of the specimen. After the LSP process, the fatigue life limit was increased by 16%, and the S–N curve shifted upward. Then, based on the theory of mean stress, the mechanism whereby the compressive residual stress improves the fatigue life of Ti6Al4V titanium alloy was analyzed. It indicated the improvement in fatigue life was because of the high-amplitude compressive residual stress on the surface and in depth induced by LSP to reduce the tensile stress produced by external loading. In addition, the scanning electron microscope (SEM) pattern of fatigue fracture demonstrated distinct differences in the fracture morphology before and after LSP. After LSP, the crack initiation sites of the samples moved to the subsurface where it was difficult for fatigue cracks initiating here. Moreover, after the LSP process, there were high density of fatigue striations and many secondary cracks on the fracture of the treated specimen. Full article