Optimum Deposition Conditions Research Articles

Hydrogen Evolution Reaction of Electrodeposited Ni-W Films in Acidic Medium and Performance Optimization Using Machine Learning.

Ni-W alloy films were electrodeposited from a gluconate aqueous bath at pH=5.0, at varying current densities and temperatures. While there is little to no difference in composition, i. e., all films possess ~12 at.% W, their activity at hydrogen evolution reaction (HER) in acidic medium is greatly influenced by differences in surface morphology. The kinetics of HER in 0.5 M H2SO4 indicates that the best performing film was obtained at a current density of -4.8 mA/cm2 and 50 °C. The Tafel slopes (b) and the overpotentials at a geometric current density of -10 mA/cm2 (η10) obtained for 200 cycles of linear sweep voltammetry (LSV) from a set of films deposited using different parameters were fed into a machine learning algorithm to predict optimum deposition conditions to minimize b, η10, and the degradation of samples over time. The optimum deposition conditions predicted by the machine learning model led to the electrodeposition of Ni-W films with superior performance, exhibiting b of 33-45 mV/dec and an η10 of 0.09-0.10 V after 200 LSVs.

Pulse-constructed energy–saving PbO2 electrode for copper electrowinning

Energy-saving PbO2 exhibit significant application potential in the non-ferrous metal electrowinning industry. By optimizing the deposition time, heteropolar spacing, nitric acid concentration, pulse current density and pulse frequency, the optimum conditions for deposition of PbO2 electrode were obtained. Meanwhile, the effects of electrodeposition parameters on the electrochemical performance, phase structure and morphology of β-PbO2 were systematically evaluated. The mechanism of action of pulse and direct current deposition was proposed. The simulated copper electrowinning experiment shows that an improved current efficiency (91.6 %) was achieved and the low energy consumption (1855.1 kW⋅h/t) for copper production per ton was significantly reduced. Compared with the electrode prepared by direct current deposition, the current efficiency of copper is increased by 4.3 % and the energy consumption is reduced by 198.6 kWh/t. Additionally, the PbO2 electrode produced by the optimized pulse deposition process exhibits excellent stability, which service-time is increased by approximately 99.4 %. This research offers insights for developing energy-efficient and long-lived electrode materials.

Modelling-assisted geometrical optimization of colloidal quantum color convertor based pixels fabricated by dielectrophoretic directed assembly

Hypothesis: Building competitive color conversion pixels for microdisplays made of semiconductor nanocrystals requires reaching a deposition thickness high enough to absorb all the blue light from the backlight unit. In the case of dielectrophoretic directed assembly of such nanocrystals, modeling and simulations may help understand what the intrinsic limitations of the process are, and may be used to propose new assembly routes.Experiments: A theoretical model of dielectrophoretic interactions between polarizable nano-spheres and an electrostatically patterned substrate has been developed. Monte Carlo simulations have been run using this model to rationalize the effects of parameters driving the dielectrophoretic directed assembly and to find optimal deposition conditions for reaching a maximal thickness of nanocrystal pixels. Experiments with CdSe quantum plates and with alumina spheres embedding quantum plates (micro-pearls) have been carried out and compared to the model.Findings: Modeling and simulations reveal that the directed assembly of semiconductor nanocrystals is limited essentially by the small object size, which sets the maximum dielectrophoretic force they can undergo. They indicate that using larger objects should allow reaching unprecedented assembly heights, but will induce lateral extension of the assembly. This trade-off has been illustrated with diagrams in the parameter space and confirmed experimentally with micro-pearls.

Charged Microdroplets Deposition for Nanostructured-Based Electrode Surface Modification

Accelerated synthesis of gold nanoparticles (AuNPs) in charged microdroplets produced by electrospray ionization (ESI) was exploited to modify the surface of graphite screen-printed electrodes (GSPEs). The deposited AuNPs were then functionalized by the charged microdroplets deposition of 6-ferrocenyl-hexanethiol (6Fc-ht) solutions that act as reducing and stabilizing agents and provide electrochemical properties for the modified electrodes. The morphology and composition of the AuNPs were characterized by scanning electron microscopy (SEM). Cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) were used to investigate the electrochemical behavior of the modified electrodes. The results showed that the ESI microdroplets deposition technique produces uniform and well-dispersed AuNPs on GSPE, and optimal conditions for deposition were identified, enhancing GSPE electrocatalytic performance. Further functionalization by ESI microdroplets of AuNPs with 6Fc-ht demonstrated improved redox properties compared with the conventional self-assembled monolayer (SAM) method, highlighting the technique’s potential for the easy and fast functionalization of electrochemical sensors.

Electrochemical Detection of Cd2+ and Pb2+ in Wastewater by Amino C-dot-MOF/GCE

Carbon dots(C-dots) and metal-organic frameworks (MOFs) have found widespread applications in sensing, energy storage, and catalysis, yet their utilization in electrochemical sensing remains relatively limited. This study focuses on the preparation of C-dots/UiO-66-NH2 as a modified material on glassy carbon electrodes to detect cadmium and lead ions in water using electrochemical methods. The material was created by utilizing m-phenylenediamine as a C-dots source and amino-functionalized zirconium-based metal-organic frameworks, combining these two popular materials. The presence of amino groups in the structure facilitated the complexation with metal ions, providing an effective interface for metal ion adsorption. Under optimized deposition conditions, C-dots/UiO-66-NH2 demonstrated excellent linearity and low detection limits for metal ions (Cd2+ and Pb2+) within the concentration range of 30 to 180 μg l−1. The limits of detection (LOD) were LOD(Cd) = 2.16 μg l−1 and LOD(Pb) = 1.08 μg l−1 for individual detection, and LOD(Cd) = 2.62 μg l−1 and LOD(Pb) = 1.36 μg l−1 for simultaneous detection. These results highlight the suitability of C-dots/UiO-66-NH2 for the determination of Cd2+ and Pb2+ in water. Furthermore, the C-dots/UiO-66-NH2/GCE sensor exhibited robust immunity to interference and maintained detection stability, showcasing its potential for practical applications.

ZnO thin films co-doped with III-valence metals and halogens: theory and experiment

The efficiency of metal-halogen co-doping of ZnO thin films deposited by DC magnetron sputtering of ceramic targets has been studied theoretically and experimentally. The influence of deposition temperature (300 − 900 K range), ZnX2 pressure (10−10−1 atm), Me2O3 dopant concentration (10−3 − 10 mol %), and Zn pressure (10−14 − 10−6 atm) on the composition of ZnO − Me2O3 − ZnX2 − Zn (Me = Al, Ga, In; X = F, Cl, Br, I) systems has been analyzed theoretically. The surface migration velocity of oxides and halides is also estimated for a wide temperature range. According to the calculation results, the optimal deposition conditions have been recommended. ZnO thin films co-doped with Al+Cl, Ga+Cl, Ga+Br, Ga+I, and In+Cl were deposited using ZnO:Me:X ceramic targets sintered by chemical vapor transport based on halides. The influence of the stoichiometric deviation of ceramic targets, the concentration of halogens, and metal impurities on thin films’ electrical, structural, compositional, and optical properties has been investigated. It is shown that Ga+Cl+Zn co-doping is the most promising. This co-doping increases both the structural perfection of films (electron mobility) and doping efficiency by Ga (charge carrier concentration), reducing the resistivity of thin films by two times compared to the use of classical ZnO:Ga ceramic targets. The optimal stoichiometric deviation of ZnO:Me:X ceramics targets, corresponding to the highest electron mobility and figure of merit of thin films, has been recommended.

Nanostructured thin film SrCo0.8Nb0.1Ta0.1O3-δ cathode for low-temperature solid oxide fuel cells

Nanostructured perovskite-type cathodes are considered essential for the realization of high-performance solid oxide fuel cell (SOFC). However, perovskite-type cathode materials demonstrating high electrochemical performance in the low-temperature operating region below 600° are limited. SrCo0.8Nb0.1Ta0.1O3-δ (SCNT) has been identified as a material that exhibits exceptional performance even in the low-temperature region of 500 °C. This paper investigates the growth behavior and electrochemical properties of SCNT thin films for SOFC cathode applications. Pulsed laser deposition (PLD) was employed to fabricate SCNT films under varying chamber pressures: 5 mTorr, 75 mTorr, and 150 mTorr. Systematic analysis through X-ray diffraction and X-ray photoelectron spectroscopy indicates that the structural factors of PLD perovskite oxide nanostructures, such as grain size, porosity, and in-plane connectivity, are intricately influenced by deposition pressure without affecting crystallinity and chemical composition. The findings demonstrate that achieving desired electrochemical properties of the nanostructured PLD perovskite oxide necessitates specific optimal deposition conditions for these structural parameters. Electrochemical assessments revealed an optimal nanostructure achieved with 1200 nm at 75mTorr, demonstrating enhanced power density due to increased active reaction surface area, which significantly reduced resistances in ohmic and polarization. Excessive thickness, however, led to performance decline due to film delamination. Integration of optimized SCNT films into an anodic aluminum oxide supported thin film SOFC exhibited 907 mW/cm2 of peak power density at 550 °C.

Effect of Deposition Parameters on Micromechanical Properties and Machining Performance of CrN Coating for Wet Finish Turning of Ti6Al4V Alloy.

This study aims to optimize the performance of CrN coatings deposited on WC cutting tools for machining Ti6Al4V alloy, where the formation of built-up edge (BUE) is a prevalent and critical issue. In-house CrN coatings were developed using the PVD (Physical Vapor Deposition) process, with variations in deposition parameters including nitrogen gas pressure, bias voltage, and coating thickness. A comprehensive experimental approach encompassing deposition, characterization, and machining performance evaluation was employed to identify the optimal deposition conditions. The results indicated that CrN coatings deposited at a nitrogen gas pressure of 4 Pa, a bias voltage of -50 V, and a thickness of 1.81 µm exhibited superior performance, significantly reducing BUE formation and tool wear. These optimized coatings demonstrated enhanced properties, such as a higher elastic modulus and a lower coefficient of friction, which contributed to improved tool life and machining performance. Comparative studies with commercial CrN coatings revealed that the in-house developed coatings outperformed the commercial variants by approximately 65% in tool life, owing to their superior mechanical properties and reduced friction. This research highlights the potential of tailored CrN coatings for advanced machining applications and emphasizes the importance of optimizing deposition parameters to achieve high-performance tool coatings.

Effect of nitrogen pressure on the microstructure, conductivity, and corrosion resistance of ZrN-coated stainless steel as bipolar plate for proton exchange membrane fuel cell

Zirconium nitride (ZrN) coatings were deposited on the stainless steel using multi-arc ion plating under varying nitrogen partial pressures (PN) ranging from 0.5 to 3.5 Pa. The effect of phase composition, microstructure, and surface morphology on the corrosion resistance and conductivity of the ZrN-coated stainless steel in a simulated proton exchange membrane fuel cell (PEMFC) cathode environment was systematically explored. XRD and TEM revealed that the columnar-structured ZrN coating mainly comprised the fcc-ZrN phase. The Zr3N4 phase was discovered near the substrate during coatings prepared at low nitrogen partial pressures. Surface defects were reduced at nitrogen partial pressures exceeding 2.5 Pa. The ZrN coating exhibited enhanced corrosion resistance and conductivity (ZrN-3.5, Ecorr = 0.307 V, Icorr = 2.085 × 10−7 A/cm2, Rct = 1.125 × 105 Ω·cm2) compared to bare stainless steel in the simulated PEMFC cathode environment. The presence of surface defects influenced the corrosion resistance, while differences in conductivity were related to the phase composition and microstructure of the coating. Thus, the findings indicate that ZrN coatings prepared under optimal deposition conditions can have potential applications in PEMFC bipolar plates.

Optimization of HVOF spraying parameters for enhanced Fe-based amorphous coatings: A taguchi approach

In this work, Fe57Cr15Mo8P10C7B3 amorphous coatings (ACs) were fabricated on 316L stainless steel (316L SS) substrate using high-velocity oxygen-fuel (HVOF) spraying technique. The Taguchi's method guided the design of L16 (43) orthogonal experiments to optimize the process parameters, including spraying distance, oxygen flow rate, and kerosene flow rate. Through statistical analyses, including signal-to-noise ratio analysis, analysis of variance (ANOVA), and response surface methodology (RSM), empirical relationships for evaluating the influence of these parameters on coating quality were established, with porosity as the primary metric. Our findings indicate a pronounced sensitivity of the porosity of the ACs to spraying conditions, in which oxygen flow rate has the most significant effect on the porosity of the ACs, while kerosene flow rate has the smallest impact. Meanwhile, it is predicted that a minimum coating porosity of 0.75 % can be achieved under the optimal deposition conditions of the spraying distance of 330 mm, the kerosene flow rate of 6.0 GPH, and an oxygen flow rate of 1900 SCF. Experimental validation confirmed these conditions, yielding coatings with superior coating quality and performance with a minimum coating porosity of 0.68 %, a microhardness of 826 ± 65 HV0.1, improved corrosion resistance in 3.5 wt% NaCl solution with a high self-corrosion potential of −0.37 V, a low self-corrosion current density of 1.08 × 10−6 A/cm2, and a low passivation current density of 1.16 × 10−5 A/cm2, and enhanced wear performance with a wear volume loss of only 4.00 × 10−5 mm3 N−1 m−1 and a friction coefficient of as low as 0.42 ± 0.022. The present study confirms the reliability of Taguchi's method in determining optimal HVOF processing parameters, evidenced by the consistency between theoretical predictions and experimental results.

Electrodeposition of MnAs-Based Thin-Film as a Possible Promising Candidate in Spintronics Applications

A thin film material obtained by Mn As co-electrodeposition was electrochemically deposited. Electrodeposition was chosen because is a versatile and easily scalable technique with low costs, and achievable under ambient conditions in water solution. These advantages are often unmatched by the typical production routes of spintronic materials. The use of different substrates was investigated, and the optimal deposition conditions were sought to reach the required morphology and composition, considering also the influence of pH and O2. The deposition conditions were optimized using multivariate analysis. The samples were characterized morphologically, crystallographically, and compositionally with SEM-EDS, XRD, and XPS, suggesting that the deposit chemical composition was predominantly constituted by MnAs and MnO2. Magnetic characterization performed with a SQUID magnetometer showed that the sample disclose a ferromagnetic component. MnAs and MnO2 are known to have properties suitable for applications in spintronics, making this system interesting as an alternative for spintronic-based devices.

Development of electrode by using gold-platinum alloy nanopar¬ticles for electrochemical detection of serum amyloid A protein

Gold-platinum alloy nanoparticles (AuPtNP) were electrochemically deposited on the surface of indium-tin-oxide (ITO) modified with (3-aminopropyl)triethoxysilane (APTES), after optimizing deposition conditions for the electroplating solution and number of deposition cycles. Different part ratios of Au/Pt used were 4/0, 3/1, 2/2, 1/3 and 0/4 (AuNP, Au3Pt1, Au2Pt2, Au1Pt3 and PtNP, respectively) in preparation of 1 mM solutions. FE-SEM, EDAX and XRD surface characterization techniques were used to confirm the presence of deposited AuPt alloy nanoparticles on the modified ITO surface. Electrochemical methods (CV, DPV and EIS) were used to investigate the electrochemical properties of prepared electrodes in the presence of ferri/ferrocyanide redox couple, which indicated the following increasing order of electrocatalytic peak current: Au < Au2Pt2 < Pt < Au1Pt3 < Au3Pt1. The most active electrode, Au3Pt1NP/APTES/ITO (with Au/Pt part ratio 3:1), was further used to fabricate the immunoelectrode SAA-Ab/Au3Pt1NP/APTES/ITO. The prepared immunoelec­trode was tested for detection of serum amyloid A protein biomarker (APO-SAA) by immobilising SAA-specific antibodies (SAA ½ Ab) on its surface. Sensing studies on this immunoelectrode, performed by DPV technique, revealed the SAA biomarker detection in the linear range of 10 to 106 fg ml-1. The limit of detection was calculated as 7.0 fg ml-1.

Production and Characterization of Electrodeposited Cadmium Sulfide Semiconductor Films with Different Boron Content

AbstractIn this study, Cadmium Sulfide (CdS) semiconductor films are electrodeposited on Indium Tin Oxide (ITO) substrates at 80 °C base temperature for different boric acid (H3BO3) ratios. The effect of boric acid on these films is investigated. For this, first of all, the structural change of the films is examined. Among the films obtained with different boric acid ratios, the optimum film is achieved with 0.06 m boric acid doped. From the basic absorption spectra (αhʋ) of the obtained CdS:B films, the variation of hʋ is drawn and it is determined that the CdS:B semiconductor films has a direct band transition. From the basic absorption spectra of the obtained CdS:B films, it is observed that the CdS:B semiconductor films has a direct band transition. In addition, the optical energy bandgap values obtained are in agreement with the values in the available literatures. The results of the structural, optical, and morphological properties of the films produced in this study indicate that among the selected additive ratios, 1% boric acid gives the best and optimum deposition condition. The thin films obtained are also found to be useful as absorber layers in photovoltaic solar cells.

Plasmon assisted synthesis of TiN-supported single-atom nickel catalysts

We report the deposition of single atom nickel catalyst on refractory plasmonic titanium nitride (TiN) nanomaterials supports using the wet synthesis method under visible light irradiation. TiN nanoparticles efficiently absorb visible light to generate photoexcited electrons and holes. Photoexcited electrons reduce nickel precursor to deposit Ni atoms on TiN nanoparticles’ surface. The generated hot holes are scavenged by the methanol. We studied the Ni deposition on TiN nanoparticles by varying light intensity, light exposure time, and metal precursor concentration. These studies confirmed the photodeposition method is driven by hot electrons and helped us to find optimum synthesis conditions for single atoms deposition. We characterized the nanocatalysts using high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), energy dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). We used density functional theory (DFT) calculations to predict favorable deposition sites and aggregation energy of Ni atoms on TiN. Surface defect sites of TiN are most favorable for single nickel atoms depositions. Interestingly, the oxygen sites on native surface oxide layer of TiN also exhibit strong binding with the single Ni atoms. Plasmon enhanced synthesis method can facilitate photodeposition of single atom catalysts on a wide class of metallic supports with plasmonic properties.

Enhancing Electrical and Mechanical Properties of Conductive Textile for Wearable Embedded Systems Through Copper Electroplating

Wearable electronics, particularly electronic textiles, hold promise for significant advancements, yet their limited electrical conductivity hinders widespread application. This study examines the application of copper electrodeposition to enhance the electromechanical attributes of textronics. The conductive fabric undergoes copper electroplating for varying durations, assessing the increase in electrical conductivity relative to copper thickness. Experimental conditions span current densities from 0.2 to 20 A dm−2. Additionally, the research evaluates the mechanical resistance of the resulting interconnection with conventional electronic components. Voltammetric measurements, sheet resistance, and microscope observations establish optimal copper deposition conditions. As hypothesized, an inverse proportionality between the sheet resistance of the electrodeposited fabric and the thickness of the copper layer has been observed. This improvement raises a query: does the electromechanical reliability of e‐textiles improve with the addition of only a few micrometers of copper? The study reveals the significant enhancement of the mechanical resistance of soldered interconnections with rigid components after a few seconds of electrodeposition as well as an improvement of the quality factor of a textile antenna. In conclusion, electroplating significantly improves the electromechanical properties of textronics without compromising their wearability. This discovery paves the way for novel applications such as wireless fast charging with textile antennas.

Non-transferring arc and wire additive manufacturing: microstructure, mechanical properties and bulk texture evolution of deposits

PurposeThis study aims to demonstrate a modified wire arc additive manufacturing (AM) named non-transferring arc and wire AM (NTA-WAM). Here, the build plate has no electrical arc attachment, and the system’s arc is ignited between tungsten electrode and filler wire.Design/methodology/approachThe effect of various deposition conditions (welding voltage, travel speed and wire feed speed [WFS]) on bead characteristics is studied through response surface methodology (RSM). Under optimum deposition condition, a single-bead and thin-layered part is fabricated and subjected to microstructural, tensile testing and X-ray diffraction study. Moreover, bulk texture analysis has been carried out to illustrate the effect of thermal cycles and tensile-induced deformations on fibre texture evolutions.FindingsRSM illustrates WFS as a crucial deposition parameter that suitably monitors bead width, height, penetration depth, dilution, contact angle and microhardness. The ferritic (acicular and polygonal) and lath bainitic microstructure is transformed into ferrite and pearlitic micrographs with increasing deposition layers. It is attributed to a reduced cooling rate with increased depositions. Mechanical testing exhibits high tensile strength and ductility, which is primarily due to compressive residual stress and lattice strain development. In deposits, ϒ-fibre evolution is more resilient due to the continuous recrystallisation process after each successive deposition. Tensile-induced deformation mostly favours ζ and ε-fibre development due to high strain accumulations.Originality/valueThis modified electrode arrangement in NTA-WAM suitably reduces spatter and bead height deviation. Low penetration depth and dilution denote a reduction in heat input that enhances the cooling rate.

A rapid two-step process to prepare a high-throughput, efficient, reusable superhydrophobic–superoleophilic stainless steel mesh for oil/water separation

Currently, due to the industrial development, the direct discharge of large amounts of oil-containing wastewater has led to serious water pollution. It is necessary to develop an efficient, durable, and high-throughput material for oil–water separation. To achieve this, we prepared a nickel (Ni) coating with a loose leaf-like micro/nanostructure on the surface of stainless steel mesh (SSM), imparting it with superhydrophobic and superoleophilic properties. The deposition of ions onto the substrate was carefully controlled by adjusting the deposition parameters. Subsequently, the as-prepared Ni coating was further modified using a solution of perfluorooctyltriethoxysilane (PFOTS) in ethanol to obtain a PFOTS/Ni mesh (PNM) with excellent superhydrophobic–superoleophilic properties. Wettability tests revealed that the water contact angle (WCA) and oil contact angle (OCA) of the PNM, prepared under the optimized deposition conditions, were 161 ± 1° and 0°, respectively, with a water sliding angle (WSA) of less than 10°. Importantly, the PNM demonstrated remarkable mechanical stability in blade scratch and tape peel tests, as well as excellent chemical stability in acid-alkali resistance and electrochemical corrosion tests. And, the PNM exhibited remarkable self-cleaning capability. Additionally, PNMit filters displayed outstanding efficiency in separating oil and water (reaching 91.5%) and remarkable durability. The results indicate that the well-designed superhydrophobic–superoleophilic SSM exhibits advantages such as simple fabrication, low cost, high reusability, and strong robustness. It holds great potential for practical applications in the treatment of oily wastewater and oil spill remediation.

Enhanced interface structure of electroformed copper/diamond composites for thermal management applications

Abstract As the power density of electronic devices increases, the requirement for heat sinks with enhanced thermal properties becomes imperative for advanced heat dissipation. Copper/diamond composites are next-generation heat dissipators with high thermal conductivities, yet fabrication of these composites requires high energy and complex instruments. In this study, copper/diamond composites are fabricated by electroforming. The sediment co-deposition process is modified to obtain uniform diamond particle distribution with tailorable volume fraction. Diamond particles were initially settled on the cathode surface outside the electrolyte, and then the setup was immersed in an acidic copper sulfate electroforming bath. Varying amounts (0–100 mg l−1) of thiourea are introduced to the electrolyte to enhance the matrix–particle interface. The gaps between diamond particles are filled with electrodeposited copper using optimized deposition conditions. The composite structure detaches from the cathode by itself after the production with desired shape and dimensions. The effect of operating conditions on cathodic polarization, composite microstructure, and thermal properties are investigated. Thermal conductivity of 49 vol.% diamond containing sample fabricated with optimized parameters exceeds 667 W m−1 K−1. The increase in thermal conductivity and enhanced interface structure is attributed to the excellent void-filling ability of the optimized electrolyte.

Effect of Long-Term Sodium Hypochlorite Cleaning on Silicon Carbide Ultrafiltration Membranes Prepared via Low-Pressure Chemical Vapor Deposition.

Sodium hypochlorite (NaClO) is widely used for the chemical cleaning of fouled ultrafiltration (UF) membranes. Various studies performed on polymeric membranes demonstrate that long-term (>100 h) exposure to NaClO deteriorates the physicochemical properties of the membranes, leading to reduced performance and service life. However, the effect of NaClO cleaning on ceramic membranes, particularly the number of cleaning cycles they can undergo to alleviate irreversible fouling, remains poorly understood. Silicon carbide (SiC) membranes have garnered widespread attention for water and wastewater treatment, but their chemical stability in NaClO has not been studied. Low-pressure chemical vapor deposition (LP-CVD) provides a simple and economical route to prepare/modify ceramic membranes. As such, LP-CVD facilitates the preparation of SiC membranes: (a) in a single step; and (b) at much lower temperatures (700-900 °C) in comparison with sol-gel methods (ca. 2000 °C). In this work, SiC ultrafiltration (UF) membranes were prepared via LP-CVD at two different deposition temperatures and pressures. Subsequently, their chemical stability in NaClO was investigated over 200 h of aging. Afterward, the properties and performance of as-prepared SiC UF membranes were evaluated before and after aging to determine the optimal deposition conditions. Our results indicate that the SiC UF membrane prepared via LP-CVD at 860 °C and 100 mTorr exhibited excellent resistance to NaClO aging, while the membrane prepared at 750 °C and 600 mTorr significantly deteriorated. These findings not only highlight a novel preparation route for SiC membranes in a single step via LP-CVD, but also provide new insights about the careful selection of LP-CVD conditions for SiC membranes to ensure their long-term performance and robustness under harsh chemical cleaning conditions.

Comparative analysis of Direct Energy Deposition parameters for Ti-6Al-4V using laser beam and coaxial wire (DED-LB/CW)

This study presents a comprehensive comparison of various process parameters employed in Direct Energy Deposition (DED) using Laser Beam (LB) and Coaxial Wire (CW) techniques for Ti-6Al-4V (DED-LB/CW/Ti-6Al-4V). The main objective is to achieve flawless parts following a zero-defect strategy through the optimization of deposition conditions, focusing on the morphology of single beads and layers. These geometrical aspects are directly related to the resultant inter-run porosity and mechanical properties, thus specific criteria are stablished based on the aeronautical standard ASM 2175. Deposition processes were conducted within an inert atmosphere generated by a chamber filled with commercially pure argon. Additionally, supplementary insights are provided regarding laser-deposited Ti-6Al-4V coaxial wire in vacuum environment. Therefore, this work serves as a comprehensive investigation into optimizing DED-LB/CW parameters for Ti-6Al-4V deposition in an inert atmosphere under atmospheric pressure and vacuum for zero-defect Additive Manufacturing (AM) components.