Investigation of corrosion properties with Ni–P/TiNO coating on aluminum alloy bipolar plates in proton exchange membrane fuel cell

Aluminum alloy bipolar plates have unique application potential in proton exchange membrane fuel cell (PEMFC) due to the characteristics of lightweight and low cost. However, extreme susceptibility to corrosion in PEMFC operation condition limits the application. To promote the corrosion resistance of aluminum alloy bipolar plates, a Ni–P/TiNO coating was prepared by electroless plating and closed field unbalanced magnetron sputter ion plating (CFUMSIP) technology on the 6061 Al substrate. The research results show that Ni–P interlayer improves the deposition effect of TiNO outer layer and increase the content of TiN and TiO_xN_y phases. Compared to Ni–P and TiNO single-layer coatings, the Ni–P/TiNO coating samples exhibited the lowest current density value of (1.10 ± 0.02) × 10^?6 A·cm^?2 in simulated PEMFC cathode environment. Additionally, potential cyclic polarization measurements were carried out aiming to evaluate the durability of the aluminum alloy bipolar plate during the PEMFC start-up/shut-up process. The results illustrate that the Ni–P/TiNO coating samples exhibit excellent stability and corrosion resistance.     

Degradation rate quantification of solid oxide fuel cell performance with and without Al2TiO5 addition

Degradation rates of electrical current during constant voltage operation of SOFCs with anodes made using NiO precursor powders from two different manufacturers with and without the addition of aluminum titanate (ALT) added by either mechanical mixing or anode infiltration have been quantified using a novel MATLAB algorithm. Because the algorithm has been used to quantify degradation rates for many different SOFC tests, it is thought that the method can be applied to most measured SOFC data to quantify the instantaneous cell degradation rate as a function of time for the entire SOFC performance measurement. Degradation rates determined at different times have been plotted against varying concentrations of ALT addition, facilitating the estimation of optimum ALT concentration for SOFC anodes made with NiO from a specific manufacturer. The algorithm used to determine degradation rates is available upon request to the corresponding author.     

Evidence of nano-galvanic couple formation on in-situ formed nano-aluminum amalgam surfaces for passivation-bypassed water splitting

Reaction of Al metal with water is a well-known technique for large scale production of hydrogen. However, this method suffers from kinetic limitations due to formation of a passivation layer on Al, preventing optimal operations. Using high resolution Scanning Kelvin Probe Force Microscopy (SKPFM), we show the origin of formation of 'nano-galvanic couple' on in situ formed nano-aluminum amalgam surfaces in a water splitting system; passivation based limitations are completely bypassed in this approach. Furthermore, they offer an opportunity to beneficiate and recover mercury in contaminated water. The nano-galvanic corrosion due to substantial lateral variation in surface contact potential is responsible for the observed high throughput of hydrogen production (720 mL/min per 0.5 g Al salt). It may be noted that this process fares better than in situ prepared nano-Al based hydrogen production, wherein 600 mL/min of hydrogen is obtained for 0.5 g Al salt. Investigations using Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS) provide evidence for passivation-bypassed hydrolysis and favourable kinetics for in situ derived nano-AlHg hydrolytic agents (when compared to nano-Al). This study, to the best of our knowledge, reports the first direct proof of nano-galvanic couple formation on in-situ prepared nanoaluminum amalgam surface; paving a direct way to overcome the long standing passivation problem in Al hydrolysis. It is found that the hydrogen production rate and standard deviation (SD) of the contact potential of nanoaluminum amalgam are directly related to the rate of addition of the reducing agent, offering an opportunity for kinetic control for the in situ hydrolytic process.     

Inhibition of hydrogen production reactions in the wet dust removal system using CeCl3 solutions

For treatment of aluminum dust, a wet dust removal system has been used worldwide. During treatment, aluminum dust is inhaled into a water tank of the dust collector. As hydrogen production reactions are likely to take place in the water tank, there exists a great risk of fire or explosion accidents associated with the wet dust removal system. Based on field research and laboratory experiments, Hydrogen Inhibition Method (HIM) by using CeCl₃ solutions was proved capable of inhibiting reactions between aluminum dust and water. When the concentration of CeCl₃ solutions reached 6.02 g/L, there was basically no hydrogen gas produced. SEM, EDS and XPS characterizations were used to assess the aluminum particles before and after being reacted with water or CeCl₃ solutions, respectively. Shrinking core model was utilized to identify the corresponding chemical reaction kinetics. Additionally, a physicochemical mechanism was established to explain these phenomena.     

Stability analysis and characterization of the nano emulsified Jatropha-curcas-based bio-fuel

This work investigates the suspension duration of the nanosized multiwalled carbon nanotubes (MWCNT) and aluminum oxide (Al₂O₃) in B20, B50 and B70 blends of Jatropha Methyl ester. The MWCNT and aluminum oxide (Al₂O₃) are added to the fuel blends in the proportions of 50 and 100 pmm separately by ultra sonication. The prepared fuel samples are characterized, and turbidity analysis was done to find the stability rate of nano-additives. The outcomes reveal the maximum stability rate for MWCNT and Al₂O₃ as 83.3% and 87.03%, respectively, with 50ppm in B20 over a period of eighteen days. A considerable drop in suspension was observed with the 100 ppm MWCNT and Al₂O₃ biodiesel blends.     

Experimental investigation of solar assisted hydrogen production from water and aluminum

Sustainable production of hydrogen at high capacities and low costs is one the main challenges of hydrogen as a future alternative fuel. In this paper, a new hydrogen production system is designed and fabricated to investigate hydrogen production using aluminum and solar energy. Numerous experiments are performed to evaluate the hydrogen production rate, quantitatively and qualitatively. Moreover, correlations between the total hydrogen production volume over time and other parameters are developed and the energy efficiency and conversion ratio of the system are determined. Also, a method is developed to obtain an optimal and stable hydrogen production rate based on system scale and consumed materials. It is observed that at low temperatures, the hydrogen production volume, efficiency and COP of the system increase at a higher sodium hydroxide molarity. In contrast, at high temperatures the results are vice versa. The maximum hydrogen production volume, hydrogen production rate, reactor COP and system efficiency using 0.5 M NaOH solution containing 3.33 g lit^?1 aluminum at 30 °C are 6119 mL, 420 mL min^?1, 1261 mL H₂ per 1 g of Al, and 16%, respectively.     

Study of the solubility of Pb,Bi and Sn in aluminum by mixed CALPHAD/DFT methods: Applicability to aluminum machining alloys

The aim of this work is a formulation of a thermodynamic model for the development of new aluminum machining alloys. The three additives Bi, Pb and Sn have proven to help machining. Hence, a review of the literature showed that the liquid phase equilibria and thermodynamic data for the three binary systems Al-Bi, Al-Pb and Al-Sn is very thorough but the limited information for the FCC solution required the use of Density Functional Theory (DFT) to predict thermodynamic data. The partial heat of mixing of these three machining additives in Al(FCC) are obtained and the results helped to improve the thermodynamic model using the CALPHAD method. It was shown that for all three binary systems, the thermodynamic data obtained at three fixed compositions and that obtained for a very dilute solution gave different enthalpy curves. The thermodynamic model was used to compute the ternary systems Al-Bi-Pb, Al-Bi-Sn and Al-Pb-Sn and small adjustable parameters were added to reproduce the literature data.     

The light alloy Calphad databases PanAl and PanMg

Thermodynamic databases for multi-component aluminum alloys, PanAl, and magnesium alloys, PanMg, are reviewed and applications are highlighted. Precipitation simulations by combining thermodynamic and mobility databases for Al and Mg alloys with the PanPrecipitation module of Pandat are also demonstrated. These simulations can serve as virtual experiments to understand the effects of alloy composition and heat treatment condition on the target properties therefore provide guidance for the design of real experiments, save time and reduce cost. For PanAl the focus in this work is on 7xxx alloy and high throughput calculation (HTC) to understand/predict the effects of major and minor alloying elements on the selected properties of an alloy. For PanMg applications are exemplified in a wider spectrum of Mg alloy design and related processing parameters and the usefulness of the CALPHAD modeling tool in Mg technology is demonstrated.     

氚在305铝合金及其预生膜中渗透率的研究

文章叙述了氚在305铝合金及其预生膜中渗透率的测量方法,推导出计算氚在305铝合金及其预生膜中的渗透率的经验公式。实验结果表明氚在镀预生膜的铝中的渗透率低,在100-250℃铝表面镀层阻挡氚渗透效果极为明显,而且温度越高效果越显著。     

ZrOxNy薄膜的制备与低温电输运特性研究

针对于测温应用中对低温温度计的性能需求,为了获得灵敏度高和测温区间宽的氮氧化锆(ZrOxNy)电阻温度传感薄膜,系统研究了溅射气氛中O2流量对ZrOxNy薄膜结构和低温电输运行为的影响.采用射频反应磁控溅射工艺,通过精细调整溅射沉积过程中的O2流量在Al2O3基片上生长了系列ZrOxNy薄膜,测定了薄膜的晶体结构、形貌...