Sensors and Actuators B: Chemical, Volume 187, 2013, Pages 227-233.
Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB2 3QZ, UK.
The presence of dissolved hydrogen in molten aluminium and its alloys has a critical impact on the quality of cast aluminium components. The quantitative analysis of hydrogen in these melts is therefore of major importance in the aluminium industry. Research work conducted at the University of Cambridge and subsequent development work performed in conjunction with an industrial partner, have resulted in a novel, and now commercialised, electrochemical hydrogen sensor for aluminium melts. The sensor operates in the potentiostatic mode and relies on a proton-conducting solid electrolyte and a metal/hydrogen-based solid reference electrode. This article summarises the main steps of the underlying research and development programme, covering the actual gas sensor, test measurements in gas phases under laboratory conditions, the probe for molten metal application, and test measurements in aluminium melts under industrial conditions.
A team of researchers and engineers from the Department of Materials Science and Metallurgy, University of Cambridge, UK, and from Environmental Monitoring & Control Ltd., Stafford, UK, have developed a novel analyzer for the quantitative measurement of hydrogen dissolved in aluminum and aluminum alloy melts.
The analysis of hydrogen in molten aluminum is conventionally done either by simple but inaccurate observational methods based on the identification of bubble formation in samples taken from the melt, or by more accurate but sophisticated and time-consuming methods relying on the re-circulation of inert gas through the melt. In contrast, the new analyzer uses a solid-state electrochemical sensor, protected by a robust refractory probe, and it enables straightforward, reliable and cost-effective real-time measurements. The unit has been validated independently by various industrial organizations and is now fully commercialized.
The photograph shows the custom-built control and read-out box and, on the right, the support lance with the actual sensor located at its lower end. (Figure courtesy of Environmental Monitoring & Control Ltd.)