77883 - Surface Treatments and Coatings For Metallic Materials M

Learning outcomes

Upon successful completion of the course, students will be able to evaluate in which application it is necessary or convenient to modify the surface properties of materials in order to enhance corrosion and/or friction/wear resistance, or to develop specific chemical or physical properties. The students will be able to choose among the main surface modification and coating deposition technologies. Particular attention will be devoted to deposition methods from the vapour, liquid and solid phase.

Course contents

1. Introduction

1a. Basics on corrosion. Electrochemical (wet) corrosion: thermodynamic and kinetic aspects; protection methods. Chemical corrosion (high temperature oxidation): thermodynamic and kinetic aspects; protection methods. Coatings for corrosion protection.

1b. Basics on friction and wear: Real surfaces; Contact between surfaces; Friction; Wear processes and mechanisms; Surface treatments and coatings for tribological applications.

 

2. Coatings deposited from vapor phase (PVD, CVD and PA-CVD processes: deposition technologies, properties and structures). Duplex treatments, nanostructured and adaptive (smart) coatings, carbon-based coatings. Thermochemical diffusion treaments (carburizing, nitriding, carbonitriding and nitrocarburising, sulfurising, boriding, aluminising, chromising and sherardising).

 

3. Coatings deposited from liquid phase : Aqueous solution ((i) Electrodeposition of metallic protective coatings (chromium, nickel and zinc plating); Replacement of hard chromium coatings; Autocatalytic (electroless) deposition: Ni-P and Ni-B coatings, Ni-P matrix composite coatings. (ii) Conversion treatments (chromatising and alternative treatments; Phosphatising; Anodising; Plasma Electrolytic Oxidation)). Immersion in molten metal: hot-dip galvanizing, hot-dip aluminizing.

 

4. Coatings deposited from solid phase: thermal sprayed and welded coatings (hardfacing): deposition technologies, properties and structures. Cladding techniques.

 

5. Selection criteria for anti-friction/wear and anti-corrosion coatings and treatments: case studies and examples.

6. Methods for the characterization of coatings: morphology, roughness, composition, thickness, hardness, elastic modulus, adhesion, residual stress, fracture toughness, friction/wear and corrosion resistance.

Readings/Bibliography

Course material (all the slides used by the teacher are available in the Virtuale repository, as password-protected pdf files). Slides in Italian.

Reference textbooks:

1. B. G. Mellor (Ed.), "Surface coatings for protection against wear", Woodhead Publishing (2006).

2. L.L.Shreir et al., (Eds.), “Corrosion”, Vol.1, Newnes –Butterworths (2000).

3. G. Straffelini, "Friction and wear: Methodologies for design and control", Springer (2015).

4. I.Hutchings, P.Shipway, "Tribology: Friction and Wear of Engineering Materials", Butterworth-Heinemann (Elsevier) (2017).

5. K.Holmberg, A.Matthews, ” Coatings Tribology: Properties, Mechanisms, Techniques and Applications in Surface Engineering”, Elsevier (2009).

6. C.Donnet, A. Erdemir, “Tribology of DLC Coatings: Fundamentals and Applications”, Springer (2008).

7. H.Dong (Ed.), “Surface engineering of light alloys: Aluminium, magnesium and titanium alloys”, Woodhead (2010).

8. S.Grainger, “Engineering coatings - design and applications”, Abington Publishing, Cambridge, UK (1989)

9. ASM Handbook vol.5, “Surface Engineering”, ASM International (2010).

10. J.W. Dini, “Electrodeposition”, Noyes (1993).

Teaching methods

The course consists of:

- Lectures according to the timetable.

- Lab practicals (focusing on characterization of coated/surface treated materials).

Assessment methods

Written exam (30 multiple choice tests, 45 minutes) with short oral discussion. Exam in English can be arranged by previous contact with the teacher. Examples of previous examination papers are available in the virtuale.unibo.it repository (in Italian and in English on request) or can be made available by the teacher on request (by email).

The aim of the exam is to assess the knowledge of the main selection criteria for coatings and treatments of metallic substrates. The main criteria are based on deposition/treatment temperature, microstructure and thickness of the coating/treated layer, throwing and leveling power (ability to produce uniformly thick layers also on components with complex geometries), residual stress state (and its influence on fatigue behavior), hardness (and its influence on friction/wear behavior), adhesion, compactness, practical nobility (influence on corrosion behavior), treatable/coatable substrates.

Textbooks and electronic devices are not allowed during the exam. The grade is expressed in /30. The minimum grade for passing the exam is assigned if satisfactory knowledge of all the subjects is assessed and there are no serious gaps. The exam dates are made available in advance on the AlmaEsami web platform. Students intending to take the exam must subscribe in AlmaEsami and must show a ID document on the day of the exam.

Teaching tools

Computer and videoprojector, blackboard.

Teaching lab (equipment for metallographic preparation; optical microscopes and scanning electron microscope (SEM) with energy dispersive spectroscopy (EDS) microprobe); Vickers micro-hardness tester; scratch tester and tribometers). A laptop personal computer is required for data elaboration and presentation.

Office hours

See the website of Carla Martini

See the website of Alessandro Morri