This course relates to materials exposed to high temperatures. It can be divided into two parts: Part A – High Temperature Corrosion of materials Part B – High Temperature Mechanical behavior
In the treatment hereof a number of aspects will be addressed: High temperature applications: a) combustion engines and gas turbines b) boiler materials (heater and steam pipes) c) waste and bio mass incinerators d) solid oxygen fuel cells e) plasma-wall interactions
Materials for high temperature applications: a) Fe and Ni based alloys (Laves phases) b) superalloys c) intermetallics (TiAl, NiAl etc) d) ceramics e) composites (metal matrix and ceramic matrix) f) refractory materials and coatings g) properties-temperature relations
Course contents: Part A: High Temperature Corrosion Introduction of high temperature oxidation a) cases, applications b) methods of investigation c) accelerated test d) lifetime prediction Gas-solid interactions: oxidation, sulfidation, carburizing, nitriding a) thermodynamics b) construction of thermodynamic diagrams c) calculation of activities in gaseous environments d) oxidation, sulfidation, carburizing, nitriding Mechanisms of oxidation a) solid state diffusion, internal and external oxidation b) oxidation kinetics, nucleation c) Wagner theory d) defect chemistry Oxidation of pure metals and alloys a) scale formation and b) scale mechanical stability, stresses and adhesion c) volatile species d) selective oxidation Reactions with mixed environments a) sulfidation, carburizing, nitriding b) watervapour effects c) halogen effects d) hot corrosion e) metal dusting f) erosion effects Protective coatings a) diffusion and overlay coatings b) thermal barrier coatings c) environmental barrier coatings
Part B: Mechanical Behaviour Creep in crystalline solids (metals and ceramics) a) creep testing b) creep mechanisms c) deformation mechanism maps d) extrapolation procedures e) creep resistant materials f) creep fracture High temperature fatigue (metal alloys) a) testing b) creep-fatigue interactions c) effect of environment Thermomechanical fatigue (metal alloys) a) definitions b) role of mechanical constraint c) elastic / plastic shakedown d) testing e) TMF in super alloys: effects of phasing, crystal orientation, time, environment f) lifetime prediction models Thermal shock (ceramics)
Recommended Reading: Text book on high temperature oxidation: N. Birks, G.M. Meijer and F.S. Petit, Introduction to the High Temperature Oxidation of Metals, 2nd edition, Cambridge University Press, 2006. Text book on deformation and fracture mechanics of engineering materials: Richard Hertzberg, 4th edition, Wiley, 1996.
Learning Outcomes
By the end of the module students should be able to:
identify the different mechanisms by which creep can occur in crystalline solids and explain the principle and usage of deformation mechanism maps
perform extrapolations of creep rupture data
identify effects of temperature and environment for high-temperature fatigue
describe the conditions for which thermal/thermomechanical fatigue play a role
explain how isothermal and thermomechanical fatigue are tested and how lifetime is predicted
describe possible mechanisms of thermal/thermomechanical fatigue in high-temperature materials and identify the major affecting parameters
describe the phenomenon of thermal shock and explain the major parameters affecting this
understand gas-solid interactions; thermodynamics and reaction kinetis
understand methods of investigation for materials applied at high temperatures
give materials solutions for high temperature applications