Abstract
Hydrogen is nowadays in focus as an energy carrier that is locally emission free. Especially in combination with fuel-cells, hydrogen offers the possibility of a CO2 neutral mobility, provided that the hydrogen is produced with renewable energy. Structural parts of automotive components are often made of steel, but unfortunately they may show degradation of the mechanical properties when in contact with hydrogen. Under certain service conditions, hydrogen uptake into the applied material can occur. To ensure a safe operation of automotive components, it is therefore necessary to investigate the time, temperature and pressure dependent hydrogen uptake of certain steels, e.g., to deduct suitable testing concepts that also consider a long term service application. To investigate the material dependent hydrogen uptake, a tubular autoclave was set-up. The underlying paper describes the set-up of this autoclave that can be pressurised up to 20 MPa at room temperature and can be heated up to a temperature of 250 °C, due to an externally applied heating sleeve. The second focus of the paper is the investigation of the pressure dependent hydrogen solubility of the martensitic stainless steel 1.4418. The autoclave offers a very fast insertion and exertion of samples and therefore has significant advantages compared to commonly larger autoclaves. Results of hydrogen charging experiments are presented, that were conducted on the Nickel-martensitic stainless steel 1.4418. Cylindrical samples 3 mm in diameter and 10 mm in length were hydrogen charged within the autoclave and subsequently measured using thermal desorption spectroscopy (TDS). The results show how hydrogen sorption curves can be effectively collected to investigate its dependence on time, temperature and hydrogen pressure, thus enabling, e.g., the deduction of hydrogen diffusion coefficients and hydrogen pre-charging concepts for material testing.
Highlights
In terms of the energy transformation, it is not sufficient to develop only technologies for sustainable energy production, and technologies for energy storage or conversion.In this context, hydrogen is an excellent energy carrier
This paper presents the apparatus, exhibiting an agile thermal behaviour and ensuring to minimise hydrogen effusion, as well as the hydrogen solubilities for the martensitic stainless steel 1.4418 in dependence of pressure, time and temperature
It can be seen that the hydrogen compatibility of the material is remarkable under the applied conditions, which makes this steel interesting for applications in gaseous hydrogen
Summary
In terms of the energy transformation, it is not sufficient to develop only technologies for sustainable energy production, and technologies for energy storage or conversion. The main requirement on the autoclave was to ensure a rapid loading and unloading of the samples, in order to be able to capture the hydrogen content in the equilibrium conditions regarding applied temperature and pressure. This is necessary since hydrogen is a fast diffusing species. Diffusion coefficients are evaluated based on the investigations and the results are discussed in light of available data in the literature With this approach, the hydrogen sorption behaviour for the hydrogen uptake can be investigated, e.g., to deduct pre-charging concepts for mechanical tests. The material behaviour under application near conditions can be investigated, enabling safe and efficient component design for applications under hydrogen [16]
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