A new technique to detect localised corrosion in steel and other metals could help industry avoid major repair bills. In some cases, it could even help prevent serious safety problems in industrial plants and other building structures.
This technique differs from traditional methods as it is able to detect corrosion on a much smaller level. This means that preventative action can be taken earlier, saving money, time and possibly lives.
Funded by the Swindon-based Engineering and Physical Sciences Research Council (EPSRC), materials researchers at Sheffield Hallam University are now using the UK-developed technique to solve real industrial problems.
Corrosion can affect the structural integrity and durability of metals and alloys used in pipework, tanks and elsewhere. Although overall metal loss may be insignificant (e.g. 5%), localised corrosion can still lead to pitting which can lead on to the cracking and eventual fracture that cause leakages or more serious failures. Historically, there has been a lack of techniques able to evaluate this type of metal loss as conventional detection methods assume that corrosion takes place uniformly.
Recently, novel scanning techniques have been developed which are capable of providing useful information on local corrosion. Use of these techniques is growing in central Europe, the Far East and North America. The aim of the Sheffield Hallam initiative was to develop the UK's capability in this field through the use of the Scanning Vibrating Electrode Technique (SVET).
SVET involves scanning a vibrating electrode over the surface of a material immersed in the test solution, whilst measuring the local corrosion activity taking place at the metal-solution interface (a picture of the SVET set-up is available see details below). It differs from traditional methods because it measures this activity at a microscopic level, enabling both the rate and the distribution of localised corrosion damage to be measured. The use of a vibrating electrode also offers improved signal output and resolution over other 'new-generation' non-vibrating probe techniques. The project team has already used the SVET system to carry out a number of interdisciplinary initiatives, many involving collaboration with industry.
The team is led by Professor Bob Akid, Director of the University's Centre for Corrosion Technology. Professor Akid says: "Detecting corrosion as early as possible is of vital importance to industry. By improving industry's ability to predict the onset of damage, SVET will enable effective forecasting of maintenance regimes".
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