1. EMT 110 Engineering Materials
Lecture 1: Introduction
Teach:Dr. Rozana Aina Maulat Osman
Prepared by: Dr. Neoh

2. Grading policies Course work: 30% Assignments = 20% Examination: 70%
Quizzes = 5%
Viva/activities = 5%
Examination: 70%
Mid Term Examination = 20%
Final Examination = 50%

3. Assignments
Assignment 1 (5%): Proposal of Student Centered Learning (SCL) project
Assignment 2 (5%)
Assignment 3 (10%): Final Report for SCL project

4. Foundations of Materials Science and Engineering 5th Edition
William F. Smith
Javad Hashemi

5. Engineering materials
Materials science Investigate relationship between structure and properties materials
Materials engineering
Designing or engineering the structure to produce predetermined set of properties

6. Engineering materials
Materials are important in engineering in different areas, they are designed:
To support load
To conduct electricity
To accept or reject magnetic
To transmit or reflect light
To save cost
To survive in hostile sorrounding

7. The development of material over time
Metals: copper, tin, bronze, cast, iron, c-steels, alloy steels, aluminum, magnesium, titanium, super alloy, etc.
Polymers and Elastomers: wood, fibers, glue, rubber, nylon, epoxies, polyesters, high modulus polymers.
Ceramic and Glasses: stone, pottery, glass, cement, fused silica, technical ceramics (Al2O3, SiC)
Hybrids/Composites: paper, metal-matrix composites, ceramic composites.

8. The evolution of engineering materials with time
The evolution of engineering materials with time. Note the highly nonlinear scale. (From M. F. Ashby,
Materials Selection in Mechanical Design, 2nd ed., Butterworth-Heinemann, Oxford, 1999.)

9. Classifying Materials
3 Main Class:
Metallic Materials
Polymeric Materials
Ceramic Materials
Composite Materials (made by combining two or more of the others)
Members of a class have certain feature in common: similar properties (mechanical, thermal electrical, magnetic, and optical properties), similar processing routes, and similar applications.

10. Metals
Composed of one or more metallic elements (Iron, Copper, Aluminum)
Metallic element may combine with nonmetallic elements (carbon, nitrogen, oxygen) in relatively small amount.
Mechanical Properties:
Stiff & strong
Ductile (large amount of deformation without fracture)
Resistant to fracture.
Metallic materials have large numbers of nonlocalized electron.
Good conductors of electricity & heat
Not transparent

11. The Golden Gate Bridge north of San Francisco, California, is one of the most famous
and most beautiful examples of a steel bridge. (Courtesy of Dr. Michael Meier.)

12. Polymers
Consist of organic (carbon-containing) long molecular chains or network
Plastic & rubber materials (Poly vinyl Chloride (PVC), Polyester)
Organic compound – carbon, hydrogen & other nonmetallic elements (O, N, Si)
Mechanical Properties:
Stiffness & strength per mass are comparable to metal&ceramic
Ductile & pliable (easily formed into complex shape)
Inert chemically & unreactive in large number of environment
Tendency to soften and/or decomposed at modest temperature
Low electrical conductivity & nonmagnetic

13. Since its development during World War II, nylon fabric remains the most popular material
of choice for parachute designs. (Courtesy of Stringer/Agence France Presse/Getty Images.)

14. Ceramics
Compounds between metallic and nonmetallic elements. They are most frequently oxides, nitrides and carbides
Example: aluminum oxide, silicon dioxide, silicon nitride
Traditional ceramics: clay minerals, cement, glass
Mechanical Properties:
Stiff & strong
Very hard
Brittle (lack ductility)
Highly susceptible to fracture.
Insulative to passage of heat & harsh environment
Optical characteristic – transparent, translucent, opaque
Oxide ceramic – exhibit magnetic behaviour

15. High-temperature sodium vapor lamp made possible by use of a translucent Al2O3 cylinder
for containing the sodium vapor. (Note that the Al2O3 cylinder is inside the exterior
glass envelope.) (Courtesy of General Electric Company.)

16. Composites
Compose of two (or more) individual materials (metal, ceramic, polymer)
Design goal: to achieve a combination of properties that is not display by any single material & also to incorporate the best characteristic of each of the component.
Example: fiberglass – small glass fiber embedded within polymeric material (epoxy/polyester)
Mechanical properties of glass fiber: strong, stiff, brittle
Mechanical properties of polymer: ductile, weak, flexible
Mechanical properties of fiberglass: strong, stiff, flexible, ductile, low density

17. Overview of the wide variety of composite parts used in the Air Force’s C- 17 transport
(From Advance Composites, May/June 1988, p.53.)

18. Electronic Materials
Not a major type of material, but are extremely important for advanced engineering technology: communication satellites, advanced computers, digital watches, robots, etc.
Silicon is the most important electronic material, it is modified in various ways to change its electrical properties.

19. Future Trends
Smart Materials : Change their properties by sensing external stimulus.
Shape memory alloys: Strained material reverts back to its original shape above a critical temperature.
Used in heart valves and to expand arteries.
Piezoelectric materials: Produce electric field when exposed to force and vice versa.
Used in actuators and vibration reducers.

20. Future Trends MEMS: Microelectromechanical systems.
Miniature devices
Micro-pumps, sensors
Nanomaterials: Characteristic length < 100 nm
Examples: ceramics powder and grain size < 100 nm
Nanomaterials are harder and stronger than bulk materials.
Have biocompatible characteristics ( as in Zirconia)
Transistors and diodes are developed on a nanowire.

21. Classification and application of material’s engineering
Examples
1) Metals
Vehicle casis, engine jet component, structures (bridge, building, etc)
2) Polymers
Liquid Crystal Display (LCD), gasket, computer casing, rubber glove
3) Ceramics
Capasitor, varistor, bearing, glass, clay
4) Electronic materials
Transistor, diode, light emitting diode (LED), solar sel
5) Biomaterials
Replace natural body tissues
6) Composites
Fiberglass, aerospace material, golf club shafts, tennis rackets

22. Variety in materials
Image courtesy: Caltech Engineering Design lab handout

23. Material Properties Mechanical Properties
Density, ρ: mass per unit volume. It is important to things that moves like the design of trucks, trains, aircraft, space vehicles, etc. Aluminum has low density but lead has a high one.
Elastic modulus, E: elastic stiffness, the higher the E the stiffer it is. E.g. Steels have high E but polyethylene has low E.
Note that material stiffness is affected by its shape, its material, as well as the process that produce it.

24. Material Properties (cont.)
Yield strength, σy: relates to the permanent deformation. The larger the σy, the harder to deform permanently. E.g. titanium alloy are hard to deform permanently, but lead can.
Deformation of metal (work hardening) are sometimes used to make it stronger. However, an ultimate limit, called tensile strength, σts must be met. Beyond the limit, the material fails. The amount it stretches before it breaks is called ductility.

25. Material Properties (cont.)
Fracture toughness, K1c: the resistance of material to cracking and fracture. Most steels are tough (though they can be made brittle), whereas glass epitomizes brittleness (having low K1c ).

26. Material Properties (cont.)
Thermal Properties
Thermal properties are related to temperature.
The change of temperature may caused the falls of material strength, oxidization, degradation, and decomposition.
Maximum service temperature, Tmax: is the limiting temperature for material to work in which temperature above this limit is impractical for the material. E.g. stainless steel has a high Tmax (800ºC) whereas polymers mostly have a low Tmax.(150ºC).

27. Material Properties (cont.)
Thermal expansion coefficient, α: the amount of expansion when a material is heated up. Slight expansion of material can have significant consequences, e.g. railroad track buckles.
Metals--cool, woods—warm. This are related to thermal conductivity and heat capacity.
Thermal conductivity, λ: measures the rate at which the heat flows through the material (one side hot and the other side cold). E.g. cooking pans, radiators, and heat exchanger need high λ whereas refrigerators and space vehicles require low λ.

28. Material Properties (cont.)
Heat Capacity Cp: measures the amount of heat it takes to increase the temperature of the material. High Cp will require a lot of heat to change the temperature (e.g. copper), whereas low Cp material like polymer foams take much less.
Thermal diffusivity, a: is related to the thickness of material, the heat capacity as well as thermal conductivity. Proportional to λ/ Cp.

29. • Thermal Conductivity of Copper:
• Space Shuttle Tiles:
--Silica fiber insulation
offers low heat conduction.
• Thermal Conductivity
of Copper:
--It decreases when
you add zinc!
Fig. 19.0, Callister 6e.
(Courtesy of Lockheed
Missiles and Space
Company, Inc.)
Adapted from Fig. 19.4, Callister 6e.
(Fig is adapted from Metals Handbook: Properties and Selection: Nonferrous alloys and Pure Metals, Vol. 2, 9th ed., H. Baker, (Managing Editor), American Society for Metals, 1979, p. 315.) 5

30. Material Properties (cont.)
Electrical, magnetic, and optical properties
Electrical conductivity, Кe: electrical conductance. E.g. metals like copper and aluminum conduct well and are affordable.
Resistivity, ρe: the inverse of conductivity. E.g. insulator, fuse boxes, switch casing require resistivity to carry load, tolerate heat and survive a spark. Plastic and glass have high ρe and are often used as insulators.
Dielectric constant, εD : dielectric properties that respond to an electronic field by shifting their electrons about, even reorienting their molecules. On the other hand, material that has low εD, are immune to the field and do not respond.

31. Material Properties (cont.)
Dielectric constant is also related to the ability to allow the passage of microwave radiation.
Electricity is closely related to magnetism. Electric currents induce magnetic field whereas a moving magnet in conductor induces electric current.
‘Hard’ magnet materials like ferromagnets and ferrimagnets have the capacity to trap a magnetic field permanently. They are hard to be demagnetized once they have been magnetized. Application areas are: magnets in motor, headphones, dynamo.

32. Material Properties (cont.)
‘Soft’ magnet materials are easy to magnetize and demagnetize. E.g. transformer cores and the deflection coils of a TV tube which have the capacity to conduct a magnetic field but not retain it permanently.
remanence is a measure of the intensity of the retained magnetism.
Saturation magnetization: a measure of the coverage field the material can conduct.

33. Material Properties (cont.)
Light is an electromagnetic wave.
Some materials have the optical properties to reflect (opaque material) and refract light (transparent material).
Some materials have the ability to absorb some wavelengths (colors) while allowing others to pass freely.

34. Material Properties (cont.)
Chemical properties
Products are sometimes expose to hostile environment and expose to corrosive fluids, hot gases, and radiation.
Acid, alkalis, sweat, water are corrosive.
To survive for the product life, the product must be made or coated with materials that can tolerate the surrounding in which they operate.

35. Materials in service: wear
Photos from a pump repair company homepage (Emnor Mechanical Inc., Canada)

36. Corrosion and Oxidation
Corroded Titanic bow, rusted baking plate (Image courtesy: wiki)

37. PROPERTIES COMPARISON
Properties / Material
Metals
Ceramics
Polymers
Tensile strength
High
Low
Compression strength
Medium
Ductility
Electric and thermal conductivity
Hardness
Density
Elasticity
Toughness

38. A broad classification
Based on the specific role in an engineering application
• Structural materials (mechanical)
• Functional materials (electrical, optical,
magnetic, ...)

39. Structural versus functional
Mylar: good,structurally; bad,functionally undergoes resistive degradation with increasing temperature and humidity) 32 sheets in 0.45 mm ● Image courtesy: wiki

40. Structural versus Functional
High Tc oxide ceramic superconductors –BSCCO (bisko) –
Bismuth Strontium
Calcium Copper
Oxide: good,
functionally; bad,
structurally (brittle)
● Image courtesy: wiki

41. Processing of Materials
Different materials – should be processed
differently; Same material should be processed differently for different geometries;
Apart from material properties and geometry,
the number of components and the specifics of use (where? under what conditions? under
what constraints? how costly?)

42. Classifying Processes
Three Broad Process Families:
Primary Processes: create shapes
Secondary Processes: modify shapes
Joining and Surface Treatment
Different design will have different order of the process steps based on the need of the design