Effect of alloying elements on the contact resistance and the passivation behaviour of stainless steels

Worldwide, there are growing pressures to develop 'carbonfree' societies, where the majority of the energy is produced from renewable technologies, due to climate change [1], adverse health effects [2], fuel resource depletion [3], security of energy supply, economics [4] and increasing tight international legislations [5]. In response to the above issues, many have proposed hydrogen for use as a replacement energy carrier in future energy economies as it produces no greenhouse gases, GHGs (e.g. CO 2 ) when burned or used in a fuel cell with only electricity, heat and water being formed. A fuel cell is an 'electrochemical' device operating at various temperatures (up to 1,000°C) that continuously and efficiently convert chemical energy (from fuel and oxidant) into electrical energy. There are various types of fuel cell including alkaline (AFC), phosphoric acid (PAFC), molten carbonate (MCFC), solid oxide (SOFC) and polymer electrolyte membrane fuel cell (PEMFC) also known as the proton exchange membrane fuel cell (PEMFC) with an efficiency of up to 60% and operating up to 180°C. There are two types of PEMFC: one uses hydrogen as a fuel and the other, methanol -direct methanol fuel cell (DMFC). They both use membrane electrode assemblies (MEAs) which is the heart of the PEM fuel cell where the electrochemical reactions occur. The MEA is a multilayered membrane consisting of a polymeric membrane sandwiched between catalyst layers and gas diffusion layers (GDLs). Currently, the most promising applications for PEM fuel cell are in the automotive sector with trials of buses, cars and motorcycles becoming increasingly common. Others applications include portable, stationary or backup power units. However, the cost, performance and durability still need to be improved if PEMFC is to become a viable alternative energy technology. For example, as 'a rule of thumb', flow field plates (FFPs) constitute 10% (7.7% for a 5 kWnet stack) of the total cost and more than 60% of the weight in PEM fuel cell stacks. For this reason, the weight, volume and cost of the fuel cell stack can be reduced significantly by improving the layout configuration of FFP and use of lightweight materials. Different combinations of materials, flowfield designs and fabrication techniques have been developed for FPPs to achieve the aforementioned functions efficiently, with the main scope of obtaining high performance and economic advantages. Introduction to Flow Field PlatesThe FPP, also known as the monopolar plate (in a single cell) and bipolar plate (BPP, when used in a stack), is one of the many important components of PEM fuel cell stacks as it supplies fuel and oxidant to the MEA, removes water, collects produced current and provides mechanical support for the single cells in the stack (Figure 1) AbstractThis review describes some recent developments in the area of flow field plates (FFPs) for proton exchange membrane fuel cells (PEMFCs). The function, parameters and design of FFPs in PEM fuel cells are outlined and considered in light of their ...

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“…A method has also been devised by Kim et al [81] to measure the contact resistance of stainless steel which develops an insulating passive film.…”

Section: Interfacial Contact Resistancementioning

confidence: 99%

Polymer Electrolyte Membrane Fuel Cell (PEMFC) Flow Field Plate: Design, Materials and Characterisation

2010

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“…Chromium can be enriched in the passive films of stainless steels as a result of selective dissolution during polarization, 14,15) but the effect of alloying elements on the electric resistivity of passive film is not understood, although a research work suggests that the elements such as Cr may have an influence on the contact resistivity of stainless steels. 16) In our previous works, we found that acid treatment of stainless steels may reduce the contact resistivity to such an extent that it can be employed to produce stainless steel separators for PEFC, and this acid treatment is very low-cost. In the present study, the contact resistivity and corrosion resistance of acid-treated 316L stainless steels are investigated, and the elemental composition and thickness as well as structure of passive film on 316L stainless steel surface are analyzed with X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM).…”

Section: Introductionmentioning

confidence: 99%

Effect of Surface Composition on Contact Resistivity and Corrosion Resistance of 316L Stainless Steel

2013

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In order to produce 316L stainless steel separators with low contact resistivity and low cost, an attempt was made to reduce the contact resistivity of 316L steel by acid treatment. In the present work, the contact resistivity and corrosion resistance of acid-treated 316L stainless steels were investigated. Elemental composition, thickness and structure of the passive film on the steel surface were analyzed with transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). It is found that the contact resistivity of the stainless steel is closely related to the ratio of Fe in oxide-form in the passive film, irrespectively of the thickness of passive film. When the proportion of Fe in oxide-form to the sum of Fe and Cr in oxide-form, i.e. Feox/(Feox+Crox) is lower than ca. 40 at%, the contact resistivity is reduced to lower than 10 mΩ cm 2 . Besides, the corrosion resistance of the acid-treated stainless steel having low contact resistivity is very high. Power generation test shows that I -V characteristic and durability of the cell assembled using the acid-treated 316L steel separators of low contact resistivity are equivalent to those of the cell assembled using carbon-coated separators.

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“…Stainless steel is steel with good resistance to homogeneous or local environmental attack. Corrosion-resistant steels created have resistance only in specific conditions [1][2][3][4][5][6][7]. Their corrosion resistance depends i.a.…”

Section: Introductionmentioning

confidence: 99%

Corrosion of 1.4110 stainless steel at nitrate acid at 323 K

Kruszewski

Lipiński

2018

Engineering for Rural Development

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Abstract. Corrosion is a common process of destroying construction materials. The material during these processes loses its properties, it causes deterioration of functions, loses its usefulness, applicability. One of the important aggressive environments in the agricultural industry is nitrogen, from which nitric acid may be formed. Due to high hardness and also a good resistance to abrasion and corrosion the 1.4110 steel is commonly used in industry as knife blades, machining tools, measuring tools, pump construction, valves. Stainless steel is steel with good resistance to homogeneous or local environmental attack. The aim of the research was to determine the corrosive wear of 1.4110 steel (X55Cr), corrosion resistance with martensitic microstructure using the Huey test. The tested steel contains 0.52 % C, 13.4 % Cr and 0.65 % Mo. The samples were weighed before start of the corrosion processes and after them. Samples were kept in nitric acid 65 % at temperature 323K. The holding times of the samples in nitric acid were 48, 96, 144, 192, 240, 288, 336, 384 hours. The percentage of mass losses was determined by the weight method. Each sample was examined metallographically using an optical microscope and the surface roughness test using a profilometer. The test results were analyzed in order to determine the corrosion rate of steel in mm/year and g/m2 as well as percentage mass loss and determine the corrosion resistance in this environment. After corrosion of the steel, the roughness has increased. Mass loss and corrosion velocity were presented by a linear function, but greater accuracy is obtained by using the 3rd degree polynomial. Then it was confirmed that as the holding time in boiling nitric acid increases, corrosive wear increases. Generally, the tested steel 1.4110 has a good corrosion resistance in the nitricacid environment.Keywords: steel, stainless steel, corrosion, corrosion rate, roughness. IntroductionIn technics corrosion mainly concerns metal materials and within them also iron alloys. Stainless steel is steel with good resistance to homogeneous or local environmental attack. Corrosion-resistant steels created have resistance only in specific conditions [1][2][3][4][5][6][7]. Their corrosion resistance depends i.a. on the chemical ingredients, microstructure, surface condition. Corrosion-resistant steels have at least 10.5 % chromium and a maximum of 1.2 % carbon, elements that conduce to forming of the surface layer (passive), with dense structure and consistent with the base, causing a jump of the chemical potential, it has a tendency to self-rebuilding and provides corrosion resistance. Along with the increasing content of the chromium, nickel, molybdenum the corrosion resistance is gaining. Corrosion is a phenomenon of material damage as a result of the chemical and electrochemical environment influence [8][9][10][11][12].In alloys and metals changes occur as a result of interaction with the surrounding environment. The corrosion process begins at the point of contact with the environme...

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Effect of alloying elements on the contact resistance and the passivation behaviour of stainless steels

Cited by 79 publications

References 18 publications

Polymer Electrolyte Membrane Fuel Cell (PEMFC) Flow Field Plate: Design, Materials and Characterisation

Polymer Electrolyte Membrane Fuel Cell (PEMFC) Flow Field Plate: Design, Materials and Characterisation

Effect of Surface Composition on Contact Resistivity and Corrosion Resistance of 316L Stainless Steel

Corrosion of 1.4110 stainless steel at nitrate acid at 323 K

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