HIGH TEMPERATURE MATERIAL DEGRADATION AND DEGRADATION PROTECTION
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- Versione italiana
- Academic year
- 2022/2023
- Teacher
- ANDREA BALBO
- Credits
- 6
- Didactic period
- Primo Semestre
- SSD
- ING-IND/22
Training objectives
- High-temperature corrosion has unique industrial importance because it affects equipment and components in metals and other materials in many sectors such as aerospace, power generation, metal processing, automotive, oil and gas industry, waste incineration and chemical process industry.
This course provides technical and specialist skills and some laboratory practice, to the students which will allow them to understand the nature of high temperature corrosion phenomena and to gain know-how about methods of corrosion prevention/mitigation in a number of environments. With this aim, basic concepts about high temperature thermodynamics and kinetics, environment types where it occurs, coatings and coating technologies for high temperature corrosion mitigation, materials selection and cleaning techniques, as well as best plant design to limit corrosion attack will be described.
This knowledge will assist in:
- Identifying the causes of ongoing high temperature corrosion phenomena
- Implementing the correct choice of materials in relation to the specific environment and aggressive species
- Adopting design choices that can ensure the best corrosion resistance of the materials
- Directing towards preventive approaches suitable to avoid corrosion problems
- Proposing appropriate remedies to eliminate corrosion phenomena or at least reduce corrosion rates to acceptable levels
- Saving operational and maintenance costs. Prerequisites
- The study of high temperature corrosion and protection of metallic and ceramic materials is strongly multidisciplinary. Therefore, it requires basic integrated knowledge provided by the courses of Chemistry (about the nature and properties of atomic bonds, the solid-state structure, chemical and redox reactions), Metallurgy (microstructure of alloys, influence of heat treatments and mechanical processing), along with elementary knowledge of Physics (elementary thermodynamics concepts, first and second laws of thermodynamics and spontaneity of a reaction)).
Course programme
- The course consists of 45 hours of teaching and 15 h of laboratory practice, including a visit to laboratories where high temperature materials are produced and tested. The topics include description of high temperature degradation phenomena, high temperature materials and coatings. Some notions are supported by laboratory activity. Finally, practical case studies are presented.
Basic concepts of chemical thermodynamics and electrochemistry (2h).
Principles of high temperature corrosion: common crystal defects and point defects in ionic compounds; principles of diffusion in solid state and particularly in oxides and oxide scales; mechanisms and kinetics of oxidation; mechanical stresses during high temperature oxidation of materials (10h).
Types of high temperature corrosion: oxidation of metals and alloys; sulfidation and mixed gas corrosion of alloys; carburization and metal dusting; nitridation of alloys; corrosion in molten salts; high temperature degradation of ceramics (10h).
High temperature corrosion environments: types of environments: importance of factors such as gaseous environment composition, pressure, gas velocity, condensate composition, stress state (6h).
Oxidation in steam and steam/hydrogen environments: fireside corrosion; high temperature corrosion issues for metallic materials in solid oxide fuel cells, gas turbine oxidation and corrosion (6h).
High temperature coatings and materials (15 h)
Case studies and laboratory experiences (15 h) Didactic methods
- The course consists of lectures to explain fundamentals of high temperature corrosion with the help of a visual support (slideshow) and class discussion. For specific topics, the comprehension of the subject is sustained by a learning-by-doing method based on laboratory activity and visit to specialized laboratories.
Learning assessment procedures
- The achievement of the learning goals is assessed by an oral examination and by the quality of the report related to the laboratory activity. The final grade is formulated on account of:
- Competence achieved in the studied discipline (50%)
- Correct use of technical language and clarity of exposition (20%)
- Quality of the laboratory report which evidences the comprehension of the degradation phenomena observed in laboratory and describes possible protection methods (30%). Reference texts
- Teacher’s notes
Shreir's Corrosion, Tony J.A. Richardson Editor, Vol. I, 2010.
N. Birks, G.H. Meier, F.S. Pettit, Introduction to the High-Temperature Oxidation of Metals, Cambridge University Press, 2006.
