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".
Notes for Editors:
The research initiative "Application of the Scanning Vibrating Electrode Technique for the Assessment of Localised Corrosion" has received EPSRC funding of just over £47,000. This work is a direct spin-off of the successful Electrochemical Scanning Probe Network (ESPNET), also funded by EPSRC. For more information on ESPNET, see the website at http://www.espnet.org.
SVET was developed by Uniscan Instruments Ltd of Buxton, with input and assistance from the Centre for Corrosion Technology at Sheffield Hallam University. Original designs of stationary probes have now given way to vibrating probe systems, which, incorporated with a lock-in-amplifier, allow higher resolution and lower levels of minimum detectable signal to be achieved. A further additional technique, in terms of scanning vibrating probe methods, involves the Scanning Kelvin Probe (SKP), enabling atmospheric corrosion to be studied.
Research projects already undertaken by the SVET team at Sheffield Hallam University include:
- Corrosion of Welded Pipeline Steel Joints within Aggressive Environments: This project investigated the effectiveness of conventional "macroscopic" techniques used to detect corrosion in welds between pipes. If unchecked, corrosion of this kind can necessitate pipeline replacement. A collaboration with Corus plc.
- Assessment of Contaminated Surfaces: This project is contributing to the establishment of viable international standards to restrict the levels of water-soluble contaminants to which steels can be exposed prior to application of anti-corrosion coatings. A collaboration with Corus plc.
- Corrosion Resistance of Conversion Coatings on Zn and Zn Alloy Coated Steels: This project investigated the corrosion resistance of innovative conversion coatings that are non-toxic, non-carcinogenic and more environmentally acceptable than chromate-based systems currently in use. A collaboration with the University of Loughborough.
The Engineering and Physical Sciences Research Council (EPSRC) is the UK's main agency for funding research in engineering and the physical sciences. EPSRC invests more than £400 million a year in research and postgraduate training to help the nation handle the next generation of technological change. The areas covered range from information technology to structural engineering, and from mathematics to materials science. This research forms the basis for future economic development in the UK and improvements in everyone's health, lifestyle and culture. EPSRC also actively promotes public awareness of science and engineering. EPSRC works alongside other Research Councils with responsibility for other areas of research. The Research Councils work collectively on issues of common concern via Research Councils UK. Website address for more information on EPSRC: http://www.epsrc.ac.uk/.
For more information, contact: Prof. Bob Akid, Centre for Corrosion Technology, Materials Research Institute, Sheffield Hallam University, Tel: 0114-225-4062, E-mail: r.akid@shu.ac.uk.
A number of jpg images are available from Jane Reck, EPSRC Press Officer, Tel: 01793-444312, E-mail: jane.reck@epsrc.ac.uk. Suggested captions for the images: One corrosion.jpg: "Localised corrosion (pitting) of a 30 cm diameter stainless steel pipe after 6 weeks immersion in stagnant sea water." SVET one and SVET two.jpgs: "The scanning Vibrating Reference Electrode set-up".