Plating Coatings Research Articles

Time and Potential-Resolved Studies of Bipolar Plate Corrosion for Polymer Electrolyte Membrane Fuel Cells

Stainless steels are regarded as the reference materials for metal bipolar plates for polymer electrolyte membrane fuel cells (PEMFCs) due to their low cost and weight, high electrical conductivity, flexural strength, ease of machining, and ability to be formed into thin sheets. The main drawback is their susceptibility to corrosion in typical acidic, oxidizing environments of PEMFCs, 1,2,3 which can degrade the performance of the plate and other components of the PEMFC. The simultaneous presence of iron ions released by corrosion of the BPP and hydrogen peroxide is responsible for hydroxyl radical production, resulting in degradation of the membrane and cathode catalyst layer ionomer.4 Applying a protective coating to the metal bipolar plates is an effective way to improve its corrosion resistance.5 This work investigates corrosion rates of SS316L bipolar plates on the basis of the measured concentrations of cations (e.g., Fe, Cr, and Ni) in an aqueous electrolyte as a function of applied potential and corrosion environment.Techniques employing electrochemical flow cells (EFC) directly coupled to an inductively-coupled plasma mass spectrometer (ICP-MS) allow for more precise time- and potential-resolved detection of dissolved species. This work will report real-time data on leaching of Fe, Cr, and Ni from SS316L substrates subjected to potential cycles using a flow-through electrochemical cell coupled with an on-line ICP-MS instrument, with sub-part per billion (ppb or μg/L) sensitivity, providing the ability to resolve dissolution during potential scans. The results of this work provide a baseline for studying the efficacy of stainless steel bipolar plate coatings in mitigating degradation of PEMFCs. References Leng, P. Ming, D. Yang, C. Zhang. J. of Power Sources 451, (2020) 227783.Kumagai, S.-T. Myung, T. Ichikawa, H. Yashiro, Y. Katada, J. Power Sources 202 (2012) 92.D. Papadias, R. K. Ahluwalia, J. K. Thomson, H. M. Meyer III, M. P. Brady, H. Wang, J. A. Turner, R. Mukundan, R. Borup. J. of Power Sources 273 (2015) 1237.Elferjani, G. Serre, B. Ter-Ovanessian, B. Normand. International Journal of Hydrogen Energy 46, (2021), 32226-32241.Liu, Q. Jia, B. Zhang, Z. Lai, L. Chen. International Journal of Hydrogen Energy 47, (2022) 22915. Acknowledgements This research is supported by the U.S. Department of Energy, Energy Efficiency and Renewable Energy, Hydrogen and Fuel Cell Technologies Office under the auspices of the M2FCT consortium. Argonne National Laboratory is managed for the U.S Department of Energy by the University of Chicago Argonne, LLC under contract DE-AC-02-06CH11357.

Comparison of Corrosion Behavior of a-C Coatings Deposited by Cathode Vacuum Arc and Filter Cathode Vacuum Arc Techniques

This study explores the utilization of cathodic vacuum arc (CVA) technology to address the limitations of magnetron sputtering technology in preparing amorphous carbon (a-C) coatings, such as having a low ionization rate, low deposition rate, and insufficiently dense structure. Specifically, a-C coatings were prepared by the cathodic vacuum arc (CVA)and the filtered cathodic vacuum arc (FCVA) technology,, one with embedded carbon particles and one without, both having closely related carbon structures. Research is currently underway on bipolar plate coatings for fuel cells. The corrosion behavior of the prepared a-C coatings was examined through Tafel polarization analysis under simulated fuel cell operating conditions as well as potentiostatic analysis at 0.6 V under normal conditions and 1.6 V under start–stop conditions for 7200 s. The coatings before and after corrosion are characterized using scanning electron microscopy, energy-dispersive X-ray spectroscopy, Raman spectroscopy, and infrared spectroscopy. The results reveal that the incorporation of conductive graphite-like particles in the coatings reduces their contact resistance. However, the gaps between these particles and the coatings act as pathways for corrosive solution, exacerbating the corrosion of the coatings. After corrosion at 0.6 V, both sets of coatings with sp2-hybridized carbon structures are contaminated by elements such as hydrogen and oxygen, leading to an increase in their contact resistance. Under high potential conditions (1.6 V), large corrosion pits and defects appear at the locations of graphite-like carbon particles. Furthermore, both sets of samples exhibit more severe oxygen contamination and a transformation of broken carbon bonds from sp3- to sp2-hybridized forms, irrespective of whether embedded graphite particles are present.

Degradation mechanism analysis of a fuel cell stack based on perfluoro sulfonic acid membrane in near-water boiling temperature environment

Perfluoro sulfonic acid (PFSA)-membrane fuel cells for heavy-duty vehicle applications require elevated operating temperature, which may negatively impact the durability of proton exchange membrane fuel cells (PEMFCs). This study evaluated a 10 kW stack by conducting a 100 h driving cycle test in near-water boiling temperature. Performance degradation varied in different regions of the membrane electrode assembly (MEA), with severe degradation observed near the coolant outlet (near-water boiling temperature) and the hydrogen inlet. The rapid degradation of the MEA was examined through an analysis of its electrochemical properties, morphology, pore size, mechanical properties, degree of graphitization, and elemental composition in different regions. It was found that elevated temperatures accelerated the degradation of the PEM, leading to polymer melting, corrosion of carbon support, and the aggregation and growth of Pt nanoparticles within the MEA, ultimately the MEA structural breakdown. the MEA supporting structural breakdown. The combination of high temperatures and the loss of fluoride ions from the MEA resulted in damage to the bipolar plate coatings. Under the collaborative influence of these factors, the average voltage degradation rate of the PEMFC stack was 1.44 %@1.0 A cm−2, and the single cell with the worst degradation was up to 8.6 %@1.0 A cm−2.

Thickness Characterization of Steel Plate Coating Materials with Terahertz Time-Domain Reflection Spectroscopy Based on BP Neural Network.

Accurate monitoring of steel plate coating thickness is crucial in construction quality control and durability assessments. To address this challenge, this study introduces a terahertz time-domain reflection spectroscopy based on a BP neural network model to achieve a quantitative visualization characterization of coating thickness. The BP neural network eliminates the inherent dependence of terahertz reflection spectroscopy on the refractive index value in thickness calculation. This trained BP neural network model effectively establishes a functional relationship between signal feature parameters and the corresponding thickness values. Additionally, the proposed model can innovatively measure different coating materials' refractive indexes, revealing the corresponding values for the black paint, white paint, epoxy resin, and rubber as 2.212, 1.967, 1.924, and 2.185, respectively. The experimental results demonstrate the trained BP neural network model possesses remarkable accuracy in predicting coating thickness within the scanning area, achieving a precision level exceeding 96%. This method enables the visualization of coating thickness and the extraction of thickness characterization values. Furthermore, using the thickness imaging results as a reference, the method can accurately identify the thickness abnormalities across the scanning area, locating the position and size of potential defects such as internal scratches and foreign object defects. This innovative approach offers a superior means of monitoring and assessing the thickness distribution quality of the steel plate coating layer materials.

Enhanced corrosion resistance of LaBC film for bipolar plate coatings in proton exchange membrane fuel cells

LaB6 have been using as hot electron emission materials to serve as hollow cathode ions source, which can help to enhance forming densen films. Besides, La can easy oxide to form La2O3 which can hinder penetration of water to improve the anti-corrosion properties. Thus, we embed LaB6 in carbon which can be employed as sputtering target, expecting to hot the plasma to get more sp2 carbon involved in growth a-C films. As a result, the LaBC film show higher ID/IG values, which improves the graphitization of the carbon matrix, thus partially solving the contradiction between electrical conductivity and corrosion resistance of the LaBC film. The corrosion current density of the LaBC film coated SS316L reduced by one and two orders of magnitude compared to the a-C film coated and uncoated SS316L, respectively, which can be attributed to the formation of boron oxide and lanthanum oxide on the surface of the film. Boron oxide is a waxy substance, and under the dual obstruction of boron oxide and lanthanide oxide, the corrosive solution is difficult to penetrate into the surface and reach the substrate, which greatly delays the oxidation and corrosion of the substrate. Therefore, the LaBC film are expected to be effective bipolar plate coatings for proton exchange membrane fuel cells.

Analyzing the Efficacy of Nickel Plating Coating in Hydraulic Pipeline Drag Reduction

This study delves into the drag-reducing properties of nickel plating coatings applied to hydraulic pipelines. To investigate the drag reduction characteristics of pipeline coatings, we designed a specialized experimental apparatus to conduct deceleration experiments. The primary objective was to systematically assess the drag reduction effect of varying coating thicknesses on liquid flow within the pipeline. Chemical nickel plating was employed for preparing drag reduction coatings with diverse thicknesses, achieved through precise adjustments in the composition and operating conditions of the plating solution. In the design of the experimental apparatus, careful consideration was given to crucial parameters such as the inner diameter of the pipeline, the inlet flow rate, and the control of experimental variables. It quantitatively assesses how varying coating thicknesses, flow velocities, and pipeline diameters impact the pipelines’ resistance to flow. By meticulously measuring the pressure differential across the pipeline, the research evaluates the extent of drag reduction afforded by the coatings and simultaneously elucidates the underlying mechanisms. Findings indicate a peak drag reduction rate of 5% under conditions of a 20 µm-thick nickel coating, 5 m/s flow velocity, and a 10 mm pipeline diameter. This study aims to comprehend how coatings affect linear losses along the pipeline, thereby establishing the groundwork for optimizing drag reduction technology. These outcomes highlight the coatings’ potential to mitigate linear losses due to shear stress during fluid transport, offering a viable solution to enhance hydraulic pipeline efficiency with significant industrial implications.

Advances in development of long-term embryonic stem cell-like cultures from a marine fish, Sciaenops ocellatus

The overall goal of our research was to develop an embryonic stem cell line from red drum, Sciaenops ocellatus. These experiments were conducted to support future production of cell-based cultivated seafood products as a means towards meeting the growing global demand for sustainable seafood. Our hypothesis was that characteristics of embryonic stem cells, such as high proliferation and pluripotency, would facilitate development of a continuous cell line that could eventually be directed toward a muscle cell phenotype. We isolated embryonic stem cells from fertilized red drum eggs at the blastomere stage. These cells were seeded into culture wells at 50,000 cells/well. We tested various media, supplements, growth factors, and plate coatings to achieve growth of red drum embryonic cells. Cells at isolation reacted positively with the stem cell markers, OCT4, Nanog, and Sox2. Our cells had a fibroblast-like appearance and were maintained in culture for more than 43 days before senescence. Over time, most of the cultures showed extensive differentiation or died. The establishment of in vitro cultures of embryonic stem cell-like cells derived from red drum embryos represents progress towards developing cultured seafood products from marine fish.

Wear behavior of graded nickel-phosphorus coatings with a medium phosphorus top layer: An experimental and molecular dynamics simulation study

Nickel-phosphorus electroless plating is widely used to improve surface properties. Despite various applications in industry, mismatch properties at the interface between the Nickel-Phosphorus layer and the substrate can cause stress concentration that could fail of the interface and consequently reduce the wear resistance of the deposit. Recent studies confirmed that the graded Nickel-Phosphorus electroless plating coatings could be considered an effective approach to reducing the stress at the interface. Therefore, in this study, the graded nickel-phosphorus coatings with various phosphorus content in the form of multilayer structures were investigated. The phosphorus content in the nickel-low phosphorus layer (Ni-LP), nickel-medium phosphorus layer (Ni-MP), and nickel-high phosphorus layer (Ni-HP) were 4.88 wt%, 8.99 wt%, and 13.88 wt%, respectively. In the Ni-LP/Ni-MP double layer, the wear resistance was 1.5 times compared to the Ni-MP single layer. Using the molecular dynamics simulation, it is shown that during the wear process, the inhibition of propagation of cracks has occurred for graded structure. The experimental results showed that the higher hardness of the Ni-MP upper layer, compact surface morphology, and the crystallinty graded structure were important parameters in improving the wear resistance of the Ni-LP/Ni-MP coating. The direct relationship between the experimental parameters and the wear simulated results of the Ni-LP/Ni-MP coating also confirmed each other completely.

Advances of xenogeneic ovarian extracellular matrix hydrogels for in vitro follicle development and oocyte maturation

Research aimed at preserving female fertility is increasingly using bioengineering techniques to develop new platforms capable of supporting ovarian cell function in vitro and in vivo. Natural hydrogels (alginate, collagen, and fibrin) have been the most exploited approaches; however they are biologically inert and/or biochemically simple. Thus, establishing a suitable biomimetic hydrogel from decellularized ovarian cortex (OC) extracellular matrix (OvaECM) could provide a complex native biomaterial for follicle development and oocyte maturation. The objectives of this work were (i) to establish an optimal protocol to decellularize and solubilize bovine OC, (ii) to characterize the histological, molecular, ultrastructural, and proteomic properties of the resulting tissue and hydrogel, and (iii) to assess its biocompatibility and adequacy for murine in vitro follicle growth (IVFG). Sodium dodecyl sulfate was identified as the best detergent to develop bovine OvaECM hydrogels. Hydrogels added into standard media or used as plate coatings were employed for IVFG and oocyte maturation. Follicle growth, survival, hormone production, and oocyte maturation and developmental competence were evaluated. OvaECM hydrogel-supplemented media best supported follicle survival, expansion, and hormone production, while the coatings provided more mature and competent oocytes. Overall, the findings support the xenogeneic use of OvaECM hydrogels for future human female reproductive bioengineering.

Semi-analytical technique for the design of disordered coatings with tailored optical properties.

Disordered media coatings are finding increasing use in applications such as day-time radiative cooling paints and solar thermal absorber plate coatings which require tailored optical properties over a broad spectrum ranging from visible to far-IR wavelengths. Both monodisperse and polydisperse configurations with thickness of coatings up to 500 µm are currently being explored for use in these applications. In such cases it becomes increasingly important to explore utility of analytical and semi-analytical methods for design of such coatings to help reduce the computational cost and time for design. While well-known analytical methods such as Kubelka-Munk and four-flux theory have previously been used for analysis of disordered coatings, analysis of their utility has so far in literature been restricted to either solar spectrum or IR but not simultaneously over the combined spectrum as required for the above applications. In this work, we have analysed the applicability of these two analytical methods for such coatings over the entire wavelength range from visible to IR, and based on observed deviation from exact numerical simulation we propose a semi-analytical technique to aid in the design of these coatings with significant computational cost savings.

Adjustable TiN coatings deposited with HiPIMS on titanium bipolar plates for PEMFC

TiN coatings were deposited by HiPIMS at different N2 flow rate to improve the corrosion resistance and conductivity of metallic bipolar plates. The results show that the surface microstructure of TiN coating depends strongly on the N2 flow rate, all the samples (N2 flow rate: 4 to10 sccm) meet the DOE 2025 standard and exhibit good hydrophobicity, which has great potential for industrial application. Among them, at the N2 flow rate of 8 sccm, the TiN coating shows high compactness and the optimum surface microstructure with the lowest surface roughness of 1.083 nm and the highest hardness of 31.172 GPa. The optimized TiN coating exhibits excellent corrosion resistance with corrosion current density of 0.278 μA cm−2 and a low interfacial contact resistance value of 3.51 mΩ cm2. This work has opened a new way for the large-scale preparation of high-performance metal bipolar plate coatings.

Stochastic-Fractal Analysis Modeling of Salts Precipitation from Aqueous Solution

Electrolytes are of interest because thin plate coatings are normally obtained from aqueous solutions. The properties of the surface are important because various properties such as resistance or durability depend on it. To understand the phenomenological processes, it is better to analyze simpler processes such as sodium chloride. In this paper, a model is proposed to predict the temporal behavior of the fractal dimension of the patterns formed in salts precipitation by solvent evaporation in a scattering surface; for fractal-box counting, ImageJ software was used. The model was obtained by applying stochastic methods and fractal geometry, describing the internal fluctuations caused by precipitation and dissolution on the mesoscopic scale of solid crystalline particles. From adjusting the proposed model to the experimental data, it is possible to estimate the velocity constants related to the microscopic precipitation processes of the particles that form the pattern. The model was validated and used to study the precipitation of carbonate salts and sodium chloride, respectively, obtaining predictions corresponding to the physicochemical properties of these salts. From the adjustment of the proposed models to the observed experimental data, the value of the velocity constants of the precipitation and dissolution processes was also estimated.

Cover Image

The cover image is based on the Research Article Physically-cross-linked poly(vinyl alcohol) cell culture plate coatings facilitate preservation of cell–cell interactions, spheroid formation, and stemness by Kathleen Molyneaux et al., https://doi.org/10.1002/jbm.b.34832.

Communication—In Situ Monitoring of Interfacial Contact Resistance in PEM Fuel Cells

A new in situ method for measuring the interfacial contact resistance between the bipolar plate and gas diffusion layer of an operating PEM Fuel Cell has been developed. This method involves the insertion of probe wires, supported by a printed circuit board, between the catalyst-coated membrane and cathode side gas diffusion layer. Initial results suggest that the probe has no significant impact on fuel cell performance and produces real-time contact resistance measurements that are sensitive to changes in relative humidity and cell temperature, thus allowing the investigation of phenomena such as the oxidation of bipolar plate coatings during real operation.

Physically-cross-linked poly(vinyl alcohol) cell culture plate coatings facilitate preservation of cell-cell interactions, spheroid formation, and stemness.

We employed aqueous solutions of highly-hydrolyzed (>99+%) poly(vinyl alcohol), PVA, to coat plastic dishes as a method to efficiently induce three-dimensional (3D) culturing of cells. The coatings were prepared by simple evaporation of 3 wt/vol% solutions of PVA in water and require no additional processing steps after air drying under sterile conditions. The coating allows spheroids to form in solution. Spheroid formation is usually preferable to two-dimensional (2D) culturing as it creates a more realistic ex vivo model of some human tissues and tumors. Using PVA-coated cell culture plates, we demonstrated that we can grow reproducibly sized spheroids using several human glioma cell lines, including LN229, U87 MG, and Gli36, and the embryonic kidney cell line, 293T. Spheroids formed on PVA-coated plates grow as well as on other commercially-available, low-attachment plates, and have excellent optical imaging properties. As spheroids, LN229 cells express markers of cancer stem cells. Finally, we confirmed that spheroids generated on PVA-coated plates are sensitive to molecular perturbations, as increased expression of the cell adhesion molecule PTPμ significantly increased the size of spheroids. The PVA hydrogel layer is an effective tool for creating a more realistic ex vivo culture system than traditional 2D culture and can be used to generate cell spheroids for potential application in drug screening and personalized medicine for diseases such as cancer.

The use of tool materials for monitoring the state of cutting technological systems

The aim was to develop a methodology for monitoring the dynamic state of the links “machine tool – device – cutting tool – detail” comprising a cutting technological system as applied to turning specialized stainless steels using replaceable standard hardmetal inserts. The research object was the hard-to-treat non-corrosive stainless steels 09Х17Н7Ю, 12Х18Н10Т and 13Х15Н5 АМ-3. Monitoring was carried out by simulating plate coatings in the Deform software environment. The diagnostic criterion was the tool life period up to the wear level of 0.5 mm along the rear edge. The effect of coatings on the tool life period was assessed according to the following parameters: temperature in the cutting zone, tension in the tool material and tool deformation. As a result, 10 optimal coatings having the greatest impact on the state of the cutting technological system under study were selected. These coatings can be used for diagnosing the state of cutting technological systems. The coatings were distinguished in terms of architecture (design, composition,structure and coating method). A technique for monitoring and managing the state of cutting technological systems according to the results of diagnostics was proposed. The deviation of the revealed state of the cutting technological system from the desired state was estimated by the life period of tools with different coatings for the same time of their operation. The state of the system under study was considered effective provided that the maximum tool life period due to the use of an optimal coating was achieved. A technique allowing assessment of the state of technological cutting systems by their simulation according to the parameters “temperature in the cutting zone”, “tension in the tool material” and “tool deformation” was proposed. This technique also permits monitoring of the state of cutting systems by the parameter "tool life period" and managing their state according to the results of diagnostics through the use of the most optimal plate coatings. The developed technique can be used to reveal the optimal parameters of the cutting mode of hard-to-treat specialized corrosion-resistant steels.

Effect of Heat Treatment on Microstructure and Performance of Nano-WC Particle-Strengthened Ni Composite Coatings by Electrobrush Plating

Electrobrush plating technology has been widely used in surface remanufacturing and reinforcement and could be used to repair and reconstruct waste machinery and other products. In this paper, the effect of heat treatment on microstructure, wear resistance and thermal shock resistance of nano-WC particle-strengthened Ni composite electrobrush plating coatings was investigated using phase analysis, morphological observation, microhardness testing and coating lifetime evaluation. After heat treatment at 550°C, the cauliflower structure became more compact and the interface between coating and substrate was strengthened due to element diffusion, which led to an increase in the microhardness and coating lifetime. As the heating temperature increased, the microstructure of the coatings and substrate grew abnormally, which resulted in degradation of the coating properties. The extension of the thermal shock lifetime of the coatings after heat treatment contributed to microstructure improvement, element diffusion and new phase formation, which prolonged the times for crack initiation and propagation.

In the Race for Future Energy Provision

AbstractNo abstract.

Development of electro-copper plating with nanodiamonds for electronic interconnects in advanced packaging

In order to advance a technology suitable for fabrication of fine pitch interconnects using copper electro plating, we developed the composite of copper (Cu) and nanodiamonds (NDs). Electro-Cu plating coatings obtained by adding NDs to the electro-Cu plating bath were demonstrated to maintain a smaller crystallite size compared to the plating coatings that NDs were not added. Moreover, in case of the electro-Cu plating coatings obtained by adding NDs, smoothness of the plating coating surface and hardness of the plating coating with time course have been improved, and the electro conductivity has been improved by up to 16%. The composite material of electro-Cu plating and NDs which we developed showed the potential that it could be expected for application to fine pitch interconnects in an advanced packaging technology.

Effect of Graphene Addition on Structure and Properties of Ni–P Plating Coatings on AlCu4Mg1 Alloy

The research involved in selecting graphene as the reinforcing phase and thereby depositing graphene–Ni–P composite coatings with different graphene content on surface of AlCu4Mg1 aluminum alloy as plating. The influence of graphene concentration on the hardness, thickness, surface morphology, structure and composition of the composite coatings was tested and analyzed by mic hardness tester, digital eddy current thickness gauge, electrochemical workstation, scanning electron microscopy and X-ray diffraction, respectively. Results showed that when the graphene concentration in the electrolyte was 0.25 g/L, the hardness of the coatings was 590.3 HV, which was about 1.22 times higher than that of Ni–P coatings. It also showed that the addition of graphene of 0.25 g/L gave the coating the maximum thickness of 10 μm. The corrosion potential was the highest (− 669.8 mV) when the graphene concentration was 0.25 g/L, which was 93.88 mV higher than the Ni–P coating. Addition of graphene refined the grain of the coating, and the grain of the coating was compact and uniform.