Loading in 2 Seconds...
Loading in 2 Seconds...
Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.
Palestine Polytechnic UniversityDepartment of Mechanical EngineeringME251: Materials Science Lecturer: Dr. Maher Al-Jabari Course Objective: Introduce fundamental concepts in Materials Science Syllabus Link:http://cet.ppu.edu/depts/me/metemplate/syllabus/maher_s/Material%20Sc%20SYLLABUS.htm You will learn about: • material structure • how structure dictates properties • how processing can change structure This course will help you to: • use materials properly – material selection • realize new design opportunities with materials
Concept of Material Science and Engineering Processing Structure Properties Types level
COURSE POLICIES GRADING SYSTEM Short Exam-1 10 % Midterm Exam 30 % Short Exam-2 10 % Quizzes and Attendance 10 % Final Exam 40 % Students are required to attend all classes Unexcused absence of exams is not accepted Make-up exams are expected to be harder.
Chapter 1 - Introduction • What is materials science / engineering ? • Why should we know about it? • Materials drive our society ??????? • History • Stone Age • Bronze Age • Iron Age • Now? • Silicon Age? • Polymer Age?
Introduction Structure / Levels: Subatomic (e.g. electron, protons) Atomic (atoms and molecules) Microscopic (grains: large groups) macroscopic (by eye) Property: Response to a specified imposed stimulus Kind and magnitude Processing: Example Heat Treatment Applications: ?
Example – Biomedical - Hip Implant • Requirements • mechanical strength (many cycles) • good lubricity • biocompatibility Ball Acetabular Cup and Liner Femoral Stem
Other Applications • Industry • Metal manufacturing • Dentists ? • Think of Others • In Hebron ? • In History ? • In Future ?
Developments of New Types of Polymers • Commodity plastics Ex. Polyethylene Polypropylene Polystyrene etc. • Engineering Resins Ex. Polycarbonate Nylon Polysulfone etc.Can polypropylene be “upgraded” to properties (and price) near those of engineering resins?
Structure, Processing, & Properties (d) 30mm (c) (b) (a) 4mm 30mm 30mm • Properties depend on structure ex: hardness vs structure of steel 6 00 5 00 4 00 Hardness (BHN) 3 00 Just Keep in Mind to the end ! 2 00 100 0.01 0.1 1 10 100 1000 Cooling Rate (ºC/s) • Processing can change structure ex: structure vs cooling rate of steel
Types of Materials • Metals: Metallic bonding • Strong, ductile • high thermal & electrical conductivity • opaque, reflective. • Polymers/plastics: Covalent bonding sharing of e’s • Soft, ductile, low strength, low density • thermal & electrical insulators • Optically translucent or transparent. • Ceramics: Ionic bonding (refractory) – compounds of metallic & non-metallic elements (oxides, carbides, nitrides, sulfides) • Brittle, glassy, elastic • non-conducting (insulators) • Others: • Composite Materials ? • Semi-conductors ?
The Materials Selection Process 1. Pick Application Determine required Properties Properties: mechanical, electrical, thermal, magnetic, optical, deteriorative. 2. Properties Identify candidate Material(s) Material: structure, composition. 3. Material Identify required Processing Processing: changes structure and overall shape ex: casting, vapor deposition, forming, joining, quenching, annealing.
Properties • THERMAL • ELECTRICAL • MAGNETIC • OPTICAL
400 300 (W/m-K) 200 Thermal Conductivity 100 0 0 10 20 30 40 Composition (wt% Zinc) THERMAL • Space Shuttle Tiles: - Silica fiber insulation offers lowheat conduction. • Thermal Conductivity of Copper: -It decreases when you add zinc!
6 5 Cu + 3.32 at%Ni 4 Cu + 2.16 at%Ni Resistivity, r deformed Cu + 1.12 at%Ni 3 (10-8 Ohm-m) 2 Cu + 1.12 at%Ni 1 “Pure” Cu 0 -200 -100 0 T (°C) ELECTRICAL • Electrical Resistivity of Copper: Adapted from Fig. 18.8, Callister 7e. (Fig. 18.8 adapted from: J.O. Linde, Ann Physik5, 219 (1932); and C.A. Wert and R.M. Thomson, Physics of Solids, 2nd edition, McGraw-Hill Company, New York, 1970.) • Adding “impurity” atoms to Cu increases resistivity. • Deforming Cu increases resistivity.
Fe+ 3% Si Fe Magnetization Magnetic Field MAGNETIC • Magnetic Storage: --Recording medium is magnetized by recording head. • Magnetic Permeability vs. Composition: --Adding 3 atomic % Si makes Fe a better recording medium!
OPTICAL polycrystal: low porosity polycrystal: high porosity single crystal • Transmittance: --Aluminum oxide may be transparent, translucent, or opaque depending on the material structure.
Material Selection Factors • • Strength • Fabricability • Corrosion Resistance • Availability • Cost • Appearance
SUMMARY Course Goals: • Use the right material for the job. • Understand the relation between properties, structure, and processing. • • Recognize new design opportunities offered • by materials selection. • Do not forget the triangle: Processing Structure Properties