Learning objectives
Knowledge and understanding:
At the end of the course the student will integrate his knowledge of base chemistry with the typical application of mechanical engineering, will have a complete overview of metallic materials and will be able to correlate their chimicophysical nature with their mechanical, thermal and processing properties He will have a basic understanding also of polymeric and composite materials.
Applying knowledge and understanding:
At the end of the course of study the student will develop the ability to choose the best material for the desired applications. He will be able to predict physical and chemical processing to be implemented on materials in order to modify the structure to improve its properties. He will also be able to put in place the appropriate measures to prolong the life of the material. The student will also be able to predict the controls to be carried out to verify that the materials used meet the desired characteristics.
Making judgments:
On passing the exam, the student should have developed the ability to critically evaluate mechanical data of a material to predict their behavior when working, as well as the ability to assess the most appropriate conditions for the use of material itself.
Communication skills:
On passing the exam, the student should have acquired sufficient command of the language, at least as regards the technical terminology and specific chemical teaching.
Learning skills:
The student should have acquired the knowledge and basic skills of discipline to deal with, in the future, an independent deepening of these aspects.
Prerequisites
Having past the Chemistry exam is highly reccommended before undertaking the course
Course unit content
Theory:
Crystal and amorphous materials. Engineering materials: metals, ceramic materials, polymeric and composite materials. Mechanical, thermal and electrical properties of materials and tests for their characterization.
Crystal structures of metals. Metallic solid solutions. Crystal lattice defects and plastic deformation. Cast irons and steels: production and properties. Heterogeneous equilibria. Binary phase diagrams, their interpretation and use. The iron-iron carbide phase diagram. Steels and heat treatment (hardening, tempering, annealing, normalizing). Low-alloy steels, stainless steels. White, grey, malleable and nodular cast irons. Standard classification and codification of metal materials.
Features and preparation of copper and aluminum and their alloys major. Magnesium, titanium and nickel alloys.
Electrochemical corrosion. Galvanic cells. Corrosion for heterogeneity of solid phase. Pitting corrosion. Intergranular corrosion. Stress corrosion cracking. Dry corrosion. Protective oxide layers. Corrosion control and prevention.
Polymeric materials.
Plastics: industrial process of polymerization. Preparation of the base resins. Additives. Forming by molding, extrusion, calendering, sintering. Reaction to heat. Main types of thermoplastic and thermosetting resins and their applications.
Exercises:
Determination of the composition and phases quantity in phase diagrams.
Full programme
Properties of metals, polymers, ceramics in relation to the structure and bond types. Outline of the composite materials. Structure of metals. Space lattice and unit cells. Hexagonal and cubic lattices. Solidification. Polycrystalline materials. Grains and grain boundaries. Types of columnar and equiaxed grain structure. Solid solutions. Defects in crystals: point, line (dislocations) and surface. Mechanical properties: tensile test, nominal stress and strain, stress/strain diagram, elastic, shear and Poisson modulus. Elongation and necking. Real stress and strain. Hardness and hardness tests. Meaning of plastic deformation and the role of dislocations. Strengthening mechanisms. Work hardening. Control of the grain size. Solid solution strengthening. Ductile and brittle fracture. Toughness and resilience test; temperature of ductile-brittle transition. Fatigue behavior and fatigue test, creep of materials and creep tests. Thermal properties: expansion and conductivity. Electrical properties: conductivity and dielectric constant.
Notes on pyrometallurgical and electrometric processes for the extraction of metals. Preparation of cast iron and steel.
Phase diagrams of two components: complete miscibility in the liquid state and solid, complete miscibility in the liquid state and immiscibility in the solid state. Eutectic. Diagrams of partial miscibility in the solid state. Lever rule with exercises. Incongruent melting point. Peritectic temperature. Exercises on state diagrams. State diagram iron-iron carbide. Significant points. Perlite and ledeburite. Transformations during cooling for steel: eutettoidic, hypo- and hypereutettoidic. Steels and influence of alloying elements on the eutectoidic point.
Heat treatment of steels. Curves of Bain. Isothermal transformation diagrams (TTT curves) and continuous cooling (CCT curves). Hardening, tempering, annealing, normalizing. Surface hardening of steels: surface hardening, carburizing and nitriding. Carbon steels and low alloy steels. Alloy steel: stainless and tool. Classification of steels AISI and UNI. White and gray cast iron, malleable and ductile.
Metallurgy of copper: sulphide ore from pyrometallurgical processes. Refining of copper. Brasses and bronzes. Classification of copper alloys. Aluminum: preparation and refining. Aluminum alloys for plastic deformation and cast alloys. Classification of aluminum alloys. Magnesium alloys and their classification. Alloys of titanium and nickel.
Electrochemical corrosion, Pourbaix diagram, corrosion by the formation of galvanic cells concentration, oxygen concentration cells. Passivation. Contact galvanic corrosion, pitting corrosion, intergranular corrosion, stress corrosion. Dry corrosion. Protective oxide layers. Corrosion protection: choice of materials, coatings, design, cathodic protection.
Polymers: plastics (thermoplastics and thermosets), elastomers. Addition polymerization and polycondensation. Homopolymers and copolymers. Industrial methods of polymerization. Stereoisomerism in thermoplastic materials. Processing of polymeric materials: molding, extrusion, calendering, sintering. Additives. Polyethylene, polypropylene, polystyrene, polyvinyl chloride, teflon. Acrylic resins (PAN, PMMA). Polycondensation processes. Polyamides (nylon), polyaramids (Kevlar). Saturated polyester resins (PET, PBT) and unsaturated. Elastomers
Bibliography
Textbook:
W.F. SMITH, J.HASHEMI: "Foundations of materials science and engineering" McGraw-Hill, 2006.
C. BRISI, “Chimica Applicata”, Edizioni Levrotto e Bella, Torino, III Ed., 1997
Additional books:
A. CIGADA, T. PASTORE “Struttura e proprietà dei materiali metallici” Ed. McGraw-Hill, 2012.
Additional material available by “Centro documentazione”
Teaching methods
The course is divided into a series of oral lessons using front projection transparencies
Assessment methods and criteria
The verification of preparation consists of an oral test.
Oral examination weighted as follows:
75% Theoretical questions
Clarity of exposition
25% Exercises on phase diagrams
Other information
It is strongly reccomended to attend the course
