Polyacrylonitrile Infused in a Modified Honeycomb Aluminum Alloy Bipolar Plate and Its Acid Corrosion Resistance

Development of cellulose acetate poly acrylonitrile (CAPA)-SiC/epoxy coating to mitigate corrosion of copper in chloride containing solutions

A new conducting polymer of the cellulose acetate poly acrylonitrile (CAPA)-SiC composite was produced using an in situ oxidative polymerization technique in an aqueous medium. SiC was synthesized from Cinachyrella sp. as a source of carbon and silicon at 1200 °C under an argon atmosphere via a catalytic reduction process. The structure and morphology of the CAPA-SiC composite were characterized using surface area studies (BET), X-ray diffraction (XRD), Fourier transformation infrared spectroscopy (FT-IR), and surface morphology (SEM & TEM). To protect copper, the produced CAPA-SiC composite was mixed with commercial epoxy paint using a casting technique, and the copper surface was coated with the three components of the CAPA-SiC/epoxy paint mixture. The corrosion inhibition improvement of the CAPA-SiC/paint coating was assessed using electrochemical impedance spectroscopy followed by Tafel polarization measurements in a 3.5 wt% NaCl solution. The corrosion protection ability of the CAPA-SiC/epoxy coating was found to be outstanding at 97.4% when compared to that of a CAPA/paint coating. SEM and XRD were used to illustrate the coating on the copper surface.

Collective Enhancements on Thermal-Electrical and Mechanical Properties of Graphite-Based Composite Bipolar Plates through the Coupled Manipulations of Molding and Impregnation Pressures

The performance and durability of proton exchange fuel cells (PEMFCs) are greatly affected by the bipolar plate (BP). In this paper, the thermal and electrical conductivities and mechanical property of graphite filled with resin composite BPs were collectively enhanced through the effectively coupled manipulations of molding pressure and impregnation pressure. The microstructures show that the resin tends to distribute at the top region of the rib under high impregnation pressure. The thermal and electrical conductivities of the pure expanded graphite BP is well reserved in the composite BPs under high molding pressure, which can facilitate the heat transfer and electron conduction in the PEMFCs. The relative density and compressive strength of composite BPs were greatly enhanced by the impregnation of resin compared to the expanded graphite under high molding pressure without the impregnation of resin (HU-BP). The maximum thermal conductivity, compressive strength, and minimum interfacial contact resistance (ICR) are collectively achieved in the HL-BP. The enhanced thermal-electrical and mechanical properties could be mainly attributed to the well-reserved continuous networks of graphite in the composite BPs. The findings in this paper are expected to synergetically improve the thermal, electrical, and mechanical properties of composite BPs through coupled manipulations of the molding and impregnation pressures, which in turn enhances the power density and durability of PEMFCs.

Improving the Anti-Corrosion and Anti-Wear Performance of Anodic Coating on the Surface of AA 5052 via Hydro-Thermal Treatment

Hydro-thermal technology had been used to improve the anti-corrosion and anti-wear performance of anodizing coating on the surface of aluminium alloys. The micromorphology of the coating has been studied by SEM and results proved the coating had a compact structure. The element in the substrate had been characterized by EDS and results proved Fe had redissolved to the Al substrate. The crystalline structure of the coating had been studied by XRD and results proved the anodic coating could be transformed into η-, p- and γ-alumina. The electrochemical properties had been researched using an electrochemical workstation; results proved after the coating had been treated by hydro-thermal technology, its anti-corrosion properties could be improved. At the hydro-thermal temperature of 400 ℃, its open circuit voltage and impedance reached -0.46 V and 160 kΩ × cm2, respectively. The hardness of the coating had to be measured with an HVS-100 micro-hardness tester, with results proving that, after the hydro-thermal treatment, the hardness of the coating increased to 150 HV. The friction coefficient of the coating had been studied using a ball-on-disk tester, and the results proved it decreased to 0.46. The MMW-2 scratch tester had been used to measure the adhesion between the coating and substrate; results proved the coating had better adhesion with the substrate. The thermal conductivity of the coating had been studied by a heat conduction coefficient measurement device; results proved that it reached 11.2 W/m × K at a hydro-thermal temperature of 400 ℃, far higher than that of organic coating.

High-Performance Graphene Coating on Titanium Bipolar Plates in Fuel Cells via Cathodic Electrophoretic Deposition

In this article, we proposed a facile method to electrophoretically deposit a highly conductive and corrosion-resistant graphene layer on metal bipolar plates (BPs) while avoiding the oxidation of the metal substrate during the electrophoretic deposition (EPD). p-Phenylenediamine (PPD) was first grafted onto negatively charged graphene oxide (GO) to obtain modified graphene oxide (MGO) while bearing positive charges. Then, MGO dispersed in ethanol was coated on titanium plates via cathodic EPD under a constant voltage, followed by reducing the deposited MGO with H2 at 400 °C, gaining a titanium plate coated with reduced MGO (RMGO@Ti). Under the simulated environment of proton exchange membrane fuel cells (PEMFCs), RMGO@Ti presents a corrosion current of < 10−6 A·cm−2, approximately two orders of magnitude lower than that of bare titanium. Furthermore, the interfacial contact resistance (ICR) of RMGO@Ti is as low as 4 mΩ·cm2, which is about one-thirtieth that of bare titanium. Therefore, RMGO@Ti appears very promising for use as BP in PEMFCs.

Preparation of Nanoscale Urushiol/PAN Films to Evaluate Their Acid Resistance and Protection of Functional PVP Films

Different amounts of urushiol were added to a fixed amount of polyacrylonitrile (PAN) to make nanoscale urushiol/PAN films by the electrospinning method. Electrospinning solutions were prepared by using dimethylformamide (DMF) as the solvent. Nanoscale urushiol/PAN films and conductive Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS)/polyvinyl pyrrolidone (PVP) films were prepared by electrospinning. In order to prepare an electrospun sandwich nanoscale film, urushiol/PAN films were deposited as both the top and bottom layers and PEDOT:PSS/PVP film as the inner layer. When the PAN to urushiol ratio was 7:5, the fiber diameter ranged between 150 nm and 200 nm. The single-layer urushiol/PAN film could not be etched after being immersed into 60%, 80%, and 100% sulfuric acid (H2SO4) for 30 min, which indicated the improved acid resistance of the PAN film. The urushiol/PAN film was used to fabricate the sandwich nanoscale films. When the sandwich film was immersed into 80% and 100% H2SO4 solutions for 30 min, the structure remained intact, and the conductive PVP film retained its original properties. Thus, the working environment tolerability of the functional PVP film was increased.