This study provides principles for designing new corrosion resistant high entropy alloys. The theoretical framework is a percolation model developed by Newman and Sieradzki that predicts the ability of an alloy to passivate, i.e., to form a protective surface oxide, based on its composition. Here, their model is applied to more complex materials than previously, namely amorphous CrFeNiTa and CrFeNiW alloys. Furthermore, the model describes a more complex passivation process: reforming the oxide layer above the transpassive potential of Cr. The model is used to predict the lowest concentration of Ta or W required to extend the passive region, yielding 11–14 at% Ta and 14–17 at% W. For CrFeNiTa, experiments reveal a threshold value of 13–15 at% Ta, which agrees with the prediction. For CrFeNiW, the experimentally determined threshold value is 37–45 at% W, far above the predicted value. Further investigations explore why the percolation model fails to describe the CrFeNiW system; key factors are the higher nobility and the pH sensitivity of W. These results demonstrate some limitations of the percolation model and offer complementary passivation criteria, while providing a design route for combining the properties of the 3d transition metal and refractory metal groups. 

Research on fuel cell technology is constantly gaining importance, while global emission requirements are becoming more and more restrictive. For environmentally neutral proton exchange membrane fuel cells (PEMFCs) to become a competitive technology, sustainable infrastructures need to be established. One of the main showstoppers is the utilization of the rare and therefore costly precious metal Pt as the key element in the electrocatalysis of hydrogen and oxygen. A huge amount of research is done on immensely reducing or even replacing Pt for future PEMFC technology. In this research update, the progress on oxygen reduction reaction catalysts in acidic media over the past two years is reviewed, with special attention to their durability. © 2021 Author(s).

This paper aims to investigate the anodising behaviour of Al-Si components produced by rheocasting, to understand the effect of the surface liquid segregation (SLS) on the anodising response. The material investigated was EN AC 42000 Al-alloy with an addition of 150 ppm Sr. The component was rheocast and conventionally liquid cast for benchmarking. The RheoMetal™ process was used to prepare slurry and subsequently cast using a vertical pressure die casting machine. Prior to anodising, mechanical grinding was used as pre-treatment method for selected samples as comparison with components in the as-cast state. Anodising was performed on the components using a constant controlled voltage at 25 V, in 1 M H2 SO4, at room temperature. The duration of anodising was varied from 30 mins to 120 mins to examine the relationship between oxide layer thickness and the anodising time. The oxide layer was investigated and characterised. The results demonstrated that the presence of the SLS layer, which was enriched with alloying elements, had a significant influence on the anodising behaviour of the cast component. The oxide layer thickness of the components produced by rheocasting and fully liquid casting was measured and compared. The relations between the oxide layer thickness and anodising time, as well as the casting methods are presented and discussed in this paper..

In the eyes of industrialists, scientists often exaggerate the economic potential of their findings. The industrialists know that developing a new technology to production is associated with uncertainty and risks. To elucidate the challenges faced by the surface treatment industry, this paper discusses aspects that should be considered when making innovation out of promising research results. The Technology Readiness Level (TRL) metric for assessing maturity of a technology is discussed and exemplified. Additional risks of fluid character such as legislation, price of raw material and customer expectations are also discussed. Even though, the subject is of general relevance, the present discussion refers to surface technology and examples are given from copper plating of printed circuit boards, and durable and cost-efficient coatings on electrical connectors.

This work has explored the potential of using pulse reverse (PR) plating for increasing the deposited fraction of SiC nanoparticles. Two PR waveforms were selected, a short pulse (500 Hz) waveform and a newly modified and adapted pulsed sequence that equals the plating thickness to the particles’ diameter (50 nm) for the on-time and half-diameter during the anodic time. The pulse waveforms were designed with 4 and 10 A•dm−2 as the average current density and cathodic peak current density, respectively. Direct current (DC) deposits at the same values were also produced as reference. In all cases, the codeposition of nano-SiC particles influenced the microstructure. The electroplating under DC 10 A•dm−2 showed the strongest grain refinement and increased the content of the particles (up to 2% vol.) PR using high-frequency achieved a similar codeposition. The maximum particle incorporation was achieved by the proposed adapted pulse waveform, doubling the SiC content produced by other set-ups (up to 4% vol.); increasing the microhardness of the deposits to 400 HV, despite no grain refinement compared to the pure metal. From these results, it was observed a relationship between the influence of the plating method on the microstructure, the particle content, and the material’s hardness. 

With the introduction of fuel cell electric vehicles (FCEV), hydrogen gas produced without fossil fuels Is requiredto reduce the CO2 emissions. At the same time, the production of renewable energy is increasing. Waterelectrolysis to produce hydrogen with the use of electricity from renewable sources allows for storage of theenergy in the form of hydrogen. The gas can be utilized either back to the electric net or as fuel for FCEVs.However, the cost of water electrolysis systems needs to be reduced while the lifetime must be increased. Oneof the main limitations of the proton exchange membrane water electrolyser (PEMWE) system is the degradationof the membrane1. This limits the lifetime of the system and is expensive to replace. It has been shown thatimpurities from feed water and the degradation products from other component poison the membrane, loweringthe proton conductivity. Furthermore, metal ion impurities catalyse the formation of hydrogen peroxide at thecathode further contributing to irreversible membrane thinning2. In industrial systems, the water circulated tothe cells is purified to minimize the degradation. However, the purification limits the operating temperature ofthe systems and increases the total system cost2.The water quality used in most electrolysis cells today utilises ASTM type II deionized water. However, littleresearch is done on the limitations, and quantifying the reduction in efficiency dependent on the water quality.Dedigama et al.3 calculated the minimum flow needed, and further state that in industry, 5 times the necessaryflow of water is circulated to ensure proper wetting of the membrane. However, in research, an excess of wateris often used, up to 100 times higher flow than required, to exclude mass transport restrictions on thereactions3,4.Increasing temperature decreases the kinetic overpotential and increases the membrane conductivity4.However, also dissolution of the catalyst and degradation of the cell components increase with temperature.Furthermore, in industrial applications the maximum temperature of the water into the purification system is60°C5. Dependent on the aim of the research, experiments at temperatures as low as 25°C are performed to fitwith the industry, while others run at 80 or 90°C to probe the upper limits of current density and efficiency2.In this project we aim to analyse the effect of varying water purity on the membrane degradation in a single PEMelectrolysis cell test setup. Furthermore, the effect of changing temperature from 60 to 80°C on the impuritytolerance will be studied. The circulating feed water will be analysed with respect to conductivity, metal ion andfluorine concentration. A parallel “blank” system with only tubings, fittings etc will be assembled and comparedto the data measured from the electrolyser. Contaminating species will be added to the feed water to study theirimpact.

Backshoring of production to Western Europe has become an increasingly important trend after decades of offshoring. The subject is introduced by a general discussion followed by a specific analysis of the Nordic surface finishing industry. The main finding is that production quality is the main driver for backshoring of surface finishing. .

The bipolar plate(BPP) constitutes up to 28% of the PEMFC stack cost[1]. Cheaper and more lightweight materials are needed, while there are strict requirements on both the mechanical and chemical stability within the acidic environment of the fuel cell. The targets set by the US DOE are a corrosion current <1 μA/cm2 and interfacial contact resistance <0.01 ohm cm2[2].

Stainless steel is affordable and has the mechanical stability required for the BPPs. However, SS is subject to corrosion in the PEMFC environment. To be able to reach the DOE goals, either noble metal or conductive ceramic coatings must be utilised[3]. In this work, commercially available coatings on hydroformed SS 316L flow plates are studied. A single cell fuel cell tester is used to age the samples, and the in-situ degradation is measured by impedance measurements and polarisation curves. The electrochemical micro-cell technique is utilised to study the corrosion on both the pristine and aged flow plates by polarisation. SEM is used to analyse the surface. The aim is to better understand the pitting corrosion on PEMFC flow plates.

Fuel cell technology is becoming increasingly important in a society where the energy system is changing toward a high degree of electrification based on fossil-free primary sources of energy. Among commercial fuel cells, PEM (polymer electrolyte membrane) technology is dominating and the production is doubled each year. The reason for PEM technology being so prosperous is the ability of the industry to manufacture thin film materials (electrodes, membranes and protective films on bipolar plates), while also reaching high current densities. In order to improve the efficiency, catalysts are applied in the electrodes. These improvements have been achieved during the last decades thanks to significant materials development of membranes and electrodes, including micro- and nano-structuring and catalyst development by materials-doping. Thus, PEM technology has a strong potential to offer sustainable, cost effective and flexible solutions.

However, PEM technology is sensitive to contamination of catalysts and membrane. Additionally, the demanding internal environment (chemistry, temperature, pressure, and dynamic operation make the conditions very harsh) poses complex challenges in terms of durability. Therefore, there are still challenges to overcome to make PEM technology more efficient and robust and thereby beneficial. The most important areas of materials development to reduce the cost of PEM fuel cells are

• High-performance electrode catalysts enabling ultra-low precious metal loading,
• Lower cost, lighter, corrosion-resistant bipolar plates,
• Low cost, high-performance membranes.

The purpose of the present work is synthesis of catalytic Pt and PtP nanoparticles onto the gas diffusion layer (GDL) of PEM fuel cells by electrodeposition, and in a next step to study aging during fuel cell testing.

Pt particles with varying P concentration are electrodeposited onto the carbon paper GDL. The concentrations used were 0 at% P, 1 at% P and 10 at% P. The GDL is activated by plasma etching prior to electroplating. The electrolyte used, contained 8 gL^-1 Pt as Pt(NO₂)₂(NH₃)₂, 70 gL^-1  NaCH₃COOH and 100 gL^-1  Na₂CO₃. Phosphorous was added in the form of H3PO3. Pulsed electrodeposition was performed at a temperature of 30 °C with an on-time of 0.005 seconds and off-time of 0.195 s. The peak current was 5 A.

Leading industrial nations are investing in hydrogen technology as energy storage solution with fuel cells as the main converter to electric energy. Improvements in the performance of the key components: electrode catalyst, bipolar plates and polymer electrolyte membrane are needed to reduce costs for mass-market introduction. Consequently, surface technology has an essential role in meeting the goals.