In this ICAM webinar, Dr Kyra Sedransk Campbell, Royal Society – EPSRC Dorothy Hodgkin Research Fellow in the Department of Chemical Engineering at Imperial College London, explored the diversity of electrochemical techniques for understanding corrosion phenomena.
The wide reaching implications of corrosion problems cannot be overstated, with staggering global costs. However, it is an oversimplification to think of all the corrosion problems as a single phenomenon. We are better served to think of corrosion as a family of phenomena. The changes to the substrate in question can be chemical, electrochemical, and/or mechanical and all of these must be considered in the context of the environment in which the changes are occurring. In academia, the focus is to understand these underlying phenomena to help explain the corrosion behaviours observed. Developing this understanding is critical to developing adequate and appropriate corrosion mitigation strategies.
Faced with longer service lifetimes, higher operating temperatures, more complex loading configurations, and aggressive environments, reliable operation of many key technologies hinges upon the durability of materials or material systems. In these extreme environments, understanding the evolution of material properties may be even more important than the initial performance of the material. The oil and gas industry is ripe with extreme conditions, ranging from the chemical complexity of the carbon-based stock material to the high temperatures or pressures found during extraction, processing or use of materials.
Hydrogen embrittlement results from the diffusion of hydrogen into a metallic alloy, such as pipeline steels, and subsequent embrittlement at various trapping sites, such as grain boundaries. These traps are sites of hydrogen embrittlement, and the degree to which the traps soak up hydrogen depends upon the type of site and the enthalpy of trapping.
Professor Philip Withers FRS, Regius Professor of Materials at The University of Manchester and Chief Scientist for the Henry Royce Institute, delivered the first ICAM webinar of 2018 on ‘keeping an eye on advanced materials’.
Growth in the materials industry in the mid-20th century was driven by drop-in substitution as new materials such as plastics came to the fore, resulting in the formation of important materials-based industries. But the focus has now shifted, from simple substitution, to the creation of custom materials having tailored functionality, such as magnetic materials for data storage. In response we will have to rethink how we create new materials.
Dr Silvia Vignolini, Reader in Chemistry and Biomaterials at the University of Cambridge, delivered the final ICAM webinar of 2017 on the topic of bio-inspired photonics.
The most brilliant colours in nature are obtained by structuring transparent materials on the scale of the wavelength of visible light. By controlling/designing the dimensions of such nanostructures, it is possible to achieve extremely intense colourations over the entire visible spectrum without using pigments or colorants.
Dr Brian Connolly, EDF Energy/Royal Academy of Engineering Reader in Corrosion Performance of Energy Systems at The University of Manchester, delivered the sixth ICAM webinar of 2017 on the topic of studying corrosion to extend the life and structural integrity of materials.
Corrosion is an omnipresent concern in most industrial applications. In fact corrosion alone costs industry globally $2 trillion each year, of which £55 billion per annum is the cost to the UK and $1.37 billion per year the cost to the global Oil & Gas sector.
Professor Allan Matthews, Professor of Surface Engineering and Tribology at The University of Manchester and the Director of the BP International Centre for Advanced Materials, delivered the fourth ICAM webinar of 2017 on the topic of developing and selecting tribological coatings.
For many years, it was widely believed that the best way to reduce the wear of a surface was to make it harder. Here, Professor Allan Matthews outlines the reasons why it is in fact the ratio of the hardness to elastic modulus which gives us the best indicator of wear resistance, especially for coatings. The implications for the development of improved wear-resistant surfaces are outlined and examples of coatings which achieve this ratio were also discussed, including nanocomposite and nanolayered coatings. Mention was also given to so-called ‘duplex’ coating systems, which combine surface treatments with coatings to gain maximum tribological benefits.
“This talk will cover new approaches to sensing and analysis using optical approaches namely Raman analyse, optical coherence tomography and light sheet imaging. Examples will include whisky analysis, label free drug detection, blood analysis and applications for biomedical science.”
“Nanostructured thin films of titanium dioxide, tungsten trioxide and vanadium dioxide have been deposited using a novel electric field assisted chemical vapor deposition methodology onto glass and gas sensor substrates. Electric fields were generated during the deposition reaction by applying a potential difference across the inter-digitated electrodes of the gas sensor substrate or by applying an electric field between two transparent conducting oxide coated glass substrates. The deposited films were analyzed and characterized using scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction. It was found that applying an electric field led to large changes in film microstructure, preferential orientation and an increase in the film growth rate.
This led to improved materials properties such as increased photo-catalytic activity, enhanced wetting behavior, reduction in thermochromic transition temperature and improved supercapacitor electrode behaviour. The gas sensor properties of the films were also tested and it was found that by tuning the microstructure of the films a two to three fold enhancement in sensor response could be obtained compared to sensors deposited in the absence of an electric field. Electric field assisted chemical vapor deposition shows great promise as a method for nano-structuring and tailoring the properties of metal oxide thin films.”
“There are aspects of hydrogen in steels that are crystal clear. For example, that hydrogen in solid solution embrittles, does not require further work. The mechanism by which it embrittles is far from clear, and there is no generic theory capable of rationalising the vast quantities of data available in the published literature. When combined with the fact that practical alloys have complex mixtures of phases and defects, the confusion can be said to be complete.
However, all is not lost because measures can in principle be taken to limit the potency of hydrogen. I will begin with an introductory review of the subject, mention specific examples where significant performance enhancements have been observed, and deal with the theory and new experimental data on the passage of hydrogen through complicated mixtures of phases.”