Evaluation of machining chips and fine-grained parts of Al-10%Zn alloy in hydrogen generation

Abstract

The study of the solidification of electrochemically active alloys, with pre-programmed variation of their microstructures and morphologies, is essential in prospecting for a higher volume of hydrogen. The fundamental parameter for controlling the microstructure in this case is the solidification cooling rate. It is currently known to be highly unsustainable to continue the combustion of fossil fuels, which supply over 80% of global primary energy consumption. This opens up an opportunity for hydrogen to emerge as a critical facilitator of energy transition processes, as it is capable of producing high energy densities with little or no environmental impact. Two points still require further investigation, and for this purpose, a highly active alloy such as the Al-10%Zn alloy has been chosen: i. Application of machining chips with different starting microstructures, namely coarser and finer, in the form of briquettes, and ii. Use of parts with very refined granulometry (microstructure) produced by rapid solidification. The results could generate significant advances in terms of sustainability and viability of green or nearly green hydrogen generation, potentially boosting sectors such as naval, petroleum, gas, metallurgy, energy, and transportation. Transient solidification and centrifugal solidification techniques in a copper mold will be used to produce parts of the Al-10%Zn alloy, which will then be machined into discs. Chips with different dendritic scales (or grain sizes) will also be extracted, which will be used to produce green briquettes in disc form by compaction. Characterization will include metallography, optical and electron microscopy (SEM), EDS, and XRD, identifying/quantifying phases and morphologies of the microstructures of the discs generated under the aforementioned conditions. The corrosion rate and hydrogen production will be evaluated using an Al hydrolysis reactor employing NaOH as the electrolyte. The project aims to understand the microstructure, corrosion rate, and hydrogen rate in more sustainable alternative products of the Al-10%Zn alloy, bridging a gap towards the green use of hydrogen.