Environmental Degradation of Materials:
- Aqueous Corrosion
- High Temperature Oxidation
- Environmentally-assisted Cracking (including stress corrosion cracking, corrosion fatigue, hydrogen embrittlement, and creep)
- Flow assisted corrosion and deposition in high temperature/high pressure environments
- Irradiation Damage and Effects on Mechanical Properties
Environmental degradation has a major impact on many industrial sectors, as it is the major cause of premature, and often catastrophic, failure of engineering structures. It attracts a broad range of industrial collaborators and sponsors, and is particularly appealing to students, who see it as an area with important practical applications. The underlying science is highly interdisciplinary, linking fundamental aspects of electrochemistry and high temperature materials behaviour, physical metallurgy and engineering mechanics.
The goal of my efforts at the University of Birmingham is to establish a major research group in the area of Environmental Degradation of Materials for Energy and Electric Power Generation. The focus of the effort has targeted five industry-based themes:
- Materials degradation (including irradiation damage) in Pressurised water Nuclear power plants
- Materials for advanced/low CO2 fossil-fuel burning power plants
- Materials for advanced Oil & Gas recovery
- Material embrittlement issues in the infrastructure for the Hydrogen economy
- Materials degradation in aero and industrial turbines
Each of these industrial-based themes present challenging environmental conditions that could limit the reliability and life of structural components. The scope of environmental degradation issues is quite broad and requires specialised knowledge in the following areas:
- Localised Aqueous Corrosion
- Environmentally assisted cracking (corrosion fatigue, stress corrosion cracking, hydrogen embrittlement)
- High temperature oxidation and spallation
- Creep rupture behaviour
I have been able to develop a substantial research group with appropriate laboratory infrastructure for distinctive work in these areas. The group currently consists of 3 research fellow, 4 PhD students, 7 EngD students, and 3 Mres/MPhil/MSc students, as well as undergraduate research students. Four programmes involve investigation into material issues in nuclear power applications, three programmes involve investigation into material issues in conventional power plant applications, four programmes involve investigation of material issues in advanced oil &gas recovery applications, two programme involves investigation of materials degradation in aerospace/industrial turbines, and one programme involves investigation into hydrogen embrittlement issues of infrastructural materials for use in the hydrogen economy.
The long-term goal of my work is to develop a fundamental understanding of the mechanisms driving stress and corrosion-assisted failures of structural materials, to measure the rates of localised and stress-assisted failure processes, and to use these approaches to develop life-prediction models for critical components. The ecological drivers for improved energy efficiency are placing ever more stringent requirements on the performance of materials. Ever more reliable life prediction is therefore an ongoing challenge that requires a greater understanding of the science underlying the controlling mechanisms of environmentally-assisted failure.
Future Research Strategy
The future strategy or evolution of my research efforts will focus on three additional themes:
- Environmental degradation of advanced materials for Ultra-supercritical conventional power plants
- Environmental degradation of advanced materials for Generation IV Nuclear power plants
- Irradiation effects on mechanical properties of advanced materials for Current and next generation Nuclear power plants.
Production of a dependable energy supply for the 21st century and beyond, while limiting the emission of green house gases, offers many challenges and opportunities for materials science. Future advanced energy systems, such as those mentioned above, will require new materials that operate at dramatically higher levels of performance with respect to stress, strain, temperature, pressure and chemical reactivity.
The efficiency of conventional fossil power plants is a strong function of increased steam parameters (i.e., temperature and pressure). Significant increases in temperature could increase the efficiency of these plants from the current 35% to near 60%. These operating conditions require new materials that can withstand these environments. Advanced stainless steels and nickel-based super alloys are being developed in world-wide activity to accommodate the increased temperatures and pressures that will exist in next-generation ultra-supercritical power plants and it will be imperative to characterise their high temperature degradation behaviour to ensure safety and plant reliability.
To address the issue of sustainability of nuclear energy, fast neutron reactors must be developed, as they can typically multiply by over a factor of 50 the energy production from a given amount of uranium fuel compared to current reactors. New materials as well as fabrication and welding processes need to be developed to achieve higher performance and longer lifetimes, as well as to withstand more extreme conditions. Many challenges for materials will also be experienced in the development of Generation IV nuclear reactors where temperatures may approach 900°C. High temperature reactor technology will need a range of new materials such as advanced nickel-based alloys, refractory alloys, ceramics, advanced composites as well as advanced coatings technology. Mechanical and chemical behaviour of these materials need to be characterised and modelled in the new domains of higher temperatures and higher irradiation levels.