Corrosion and Advanced Materials Laboratory

Corrosion is not only one of the most costly forms of material degradation – it also offers a fertile area of interdisciplinary research, and can even be harnessed to make useful products such as metallic nanostructures.

A particular concern is the mechanical rupture of components due to stress corrosion cracking – the slow growth of cracks in a reactive environment. Stress corrosion failure is at the core of safety and risk analyses in several industries, including nuclear power generation. By understanding corrosion and stress corrosion mechanisms at the microscopic scale, not only can corrosion problems be mitigated, but insights can be obtained that are relevant to surprisingly remote areas of science and technology.

The main fundamental research theme of the group is the role of alloying elements in the corrosion performance of alloys. On one level, this is an atomistic issue. Computer simulation and advanced surface characterization are used to understand the dissolution, oxidation, and motion (by surface diffusion) of particular elements. Electrochemical techniques play an essential role in monitoring the kinetics of metal dissolution across semi-protective surface layers consisting of less-reactive metals and/or oxides. Molecular adsorption can be used to further modify or probe events at the interface. Relevant timescales range from seconds, in the case of an event occurring at the tip of a crack, to thousands of years, in the case of alloys used for containment of high-level nuclear waste. Alongside these atomistic considerations lies the recognition that localized corrosion of metals is an autocatalytic or coupled reaction-transport process in which the dissolution products acidify the local solution. Thus modelling skills are required to elucidate stability criteria and morphology development in localized corrosion sites; the morphologies and patterns that form deterministically in such sites are surprisingly rich.

Alongside this underlying research programme there is a vigorous activity in support of the Canadian nuclear power industry. Issues in steam-generator corrosion, waste storage and reactor component performance are being defined and offered as student projects in collaboration with industrial partners. Other industries with current corrosion issues include pulp and paper, oil and gas, and automotive, amongst others. Recently we have developed an activity in the prediction and monitoring of corrosion of steel reinforcement in concrete.

Curious nanoscale morphologies occur when elements are selectively dissolved (de-alloyed) from metallic alloys. Depending on the alloy system, the pore and ligament sizes in the resulting nanoporous structure may be stable at the 2-3 nm level, or may be coarsened in a controlled manner to hundreds or even thousands of nm, without losing the connectivity of the structure. Such materials have potential as membranes, templates, catalysts, sensor substrates, and high-surface-area electrodes, with applications in many areas such as biomedical technology, fuel cells, and filtration.

Sensor development is a natural extension of corrosion research, with common electrochemical themes. Work is proceeding on thin-film PEM-based hydrogen sensors, and sensors for deleterious metallurgical conditions in alloys, such as sigma phase in duplex stainless steels.