SUPERFICIAL TREATMENTS AND COATING OF METAL ALLOYS
Academic year and teacher
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- Versione italiana
- Academic year
- 2022/2023
- Teacher
- GIAN LUCA GARAGNANI
- Credits
- 6
- Didactic period
- Secondo Semestre
- SSD
- ING-IND/21
Training objectives
- Training objectives
The aim of the course is to give knowledge regarding the choice of the most suitable surface treatment, coatings and finishing of metallic materials for a specific industrial application. The science of surface treatment, coating and finishing is as wide as materials science, and in addition, the function of either a treatment or a coating depends not only on its nature but also on the nature of the substrate and of the interface between the substrate and the surface. In fact, the mechanical properties of a metallic material depend on its chemical composition and its microstructural features, but its operation behavior is influenced by its surface properties. The surface of a metallic component is the medium of interaction with the environment, and during its operational life, it changes physical, chemical and mechanical characteristics. Interactions with the environment can rapidly lead to a deterioration of surface properties because of either corrosion processes, related to the presence of specific chemical agents, or wear phenomena, caused by mechanical interplays. In the majority of situations, an interdisciplinary combination of various competences is necessary to design the proper solution to corrosion and wear situations. In the light of these aspects, it is necessary to grow mechanical engineers with highly developed metallurgical skills, since the industry of surface treatments and coatings is a leading productive branch within the industrial production frame.
At the end of the course, the student will be able to understand the nature and the causes of surface deterioration phenomena and to identify the most suitable solutions to properly transform surface properties in order to solve or restrain either corrosion or wear problems. The student will have to choose between the studied techniques and processes and to evaluate the influence that process variables and productions defects would have on the metallurgical features of the desired surface. Prerequisites
- The student must have a base knowledge of metal science and metallurgy and of microstructural properties of metallic alloys. Also a basic knowledge of metallographic techniques to properly prepare and investigate metallic specimens.
Course programme
- Non destructive testing and applications. Visual inspection. Liquid penetrant tests. Magnetoscopy. Radiography. Ultrasonic examination. Eddy current test. (3,0 h)
Tribology and tribological systems. Lubrication. Friction and wear mechanisms. Adesive wear, abrasive wear, fatigue wear, fretting; wear transitions. Third body theory. Friction coefficient. Factors influencing wear behaviour of metallic materials. Archard law. Tribological tests in laboratory; measure and characterization of tribological problems. Industrial case-history of tribological damage and failure (17,5 h).
Tribological coupling in human body (2,5 h).
Treatments and surface modifications (structural transformations, diffusional thermochemical treatments, conversion treatments, coating and conversion treatments, anodizing of aluminium alloys).
Improvements of material surfaces against wear and friction behaviour. Flame and induction hardening, Traditional and innovative anodizing of aluminum alloys. Shoot peening. Thermochemical tratments (carburizing, nitrocarburizing, nitriding, ionic and plasma nitriding, borizing).
Chemical and vapour deposition of thin coating films (CVD, PVD, DLC-CVD). Hot spray depositions. Hot dip and cold galvanizing (37,0 h) Didactic methods
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Learning assessment procedures
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Reference texts
- • Appunti e lucidi del docente.
• AA.VV: Manuale di trattamenti e finiture (2003), Tecniche Nuove
• G. Straffelini (2005), Attrito e usura, Tecniche Nuove (MI) (Capitolo 7: Ingegneria delle superfici in tribologia).
• K.Holmberg, A.Matthews (2009), Coatings Tribology: Properties, Mechanisms, Techniques and Applications in Surface Engineering, Elsevier (Chapter 2: Deposition processes and coating structures).
• ASM Handbook (Vol. 5) Surface Engineering
