機 械 材 料• 教授 : 陳水源 (Steven Chen)

• 班級 : 機動一 A/B( 進修一 )

• 學期 : 九十七 ( 一 )

• 選課 : 必修• 教材 : 1. “Fundamentals of Materials Science and Engineering”, 3rd. Ed. by Willia

m D. Callister, Jr. & David G. Rethwisch (Wiley, 歐亞書局 )

2. 材料科學與工程 , 原著 William D. Callister, Jr. , 簡仁德 . 楊子毅 . 張柳春譯著 ( 學銘圖書 / 歐亞書局 ), 1 & 2 擇一 .

3. 參考書 : 材料科學與工程 ( 精華版 ) ( 原著 D.R. Askeland and P.P. Phule, 歐亞“ The Science and Engineering of materials”, 4th Ed.) 張柳春 . 郭行健譯著

Materials Science and Engineering

• Materials science deals with Basic Knowledge about the Compositions, Structure, Processing Properties/Performances.

• Materials engineering deals with the Application of Knowledge gained by materials science to convert materials to products.

Knowledge and

Products

Applied Knowledge

of Materials

Materials ScienceMaterials Science and

Engineering Materials Engineering

Basic Knowledge

ofMaterials

1-4

Types of Materials• Metallic Materials

Composed of one or more metallic elements.

Example:- Iron, Copper, Aluminum.

Metallic element may combine with nonmetallic elements.

Example:- Silicon Carbide, Iron Oxide.

Inorganic and have crystalline structure. Good thermal and electric conductors.

Metals and Alloys

Ferrous Eg: Steel,Cast Iron

NonferrousEg:CopperAluminum

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Types of Materials• Polymeric (Plastic) Materials

Organic giant molecules and mostly noncrystalline.

Some are mixtures of crystalline and noncrystalline regions.

Poor conductors of electricity and hence used as insulators.

Strength and ductility vary greatly. Low densities and decomposition

temperatures.

Examples :- Poly vinyl Chloride (PVC), Polyester.

Applications :- Appliances, DVDs, Fabrics etc.

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Types of Materials

• Ceramic Materials Metallic and nonmetallic elements are chemically bonded

together. Inorganic but can be either crystalline, noncrystalline or

mixture of both. High hardness, strength and wear resistance. Very good insulator. Hence used for furnace lining for

heat treating and melting metals. Also used in space shuttle to insulate it during exit and

reentry into atmosphere. Other applications : Abrasives, construction materials,

utensils etc.

Example:- Porcelain, Glass, Silicon nitride.

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Types of Materials

• Composite Materials Mixture of two or more materials. Consists of a filler material and a binding material. Materials only bond, will not dissolve in each other. Mainly two types :-

o Fibrous: Fibers in a matrixo Particulate: Particles in a matrixo Matrix can be metals, ceramic or polymer

Examples :- Fiber Glass ( Reinforcing material in a polyester or

epoxy matrix) Concrete ( Gravels or steel rods reinforced in

cement and sand) Applications:- Aircraft wings and engine, construction.

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Types of Materials• Electronic Materials

Not Major by volume but very important.

Silicon is a common electronic material.

Its electrical characteristics are changed by adding impurities.

Examples:- Silicon chips, transistors

Applications :- Computers, Integrated Circuits, Satellites etc.

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Competition Among Materials• Materials compete with

each other to exist in new market

• Over a period of time usage of different materials changes depending on cost and performance.

• New, cheaper or better materials replace the old materials when there is a breakthrough in technology

Example:-

0

200

400

600

800

1000

1200

1400

1600

lb/C

ar1985 1992 1997

Model Year

Aluminum

Iron

Plastic

Steel

Predictions and use of materials in US automobiles.

Figure 1.14

After J.G. Simon, Adv. Mat. & Proc., 133:63(1988) and new data1-10

摘 要

Case Study – Material Selection

• Problem: Select suitable material for bicycle frame and fork.

Steel and alloys

Wood Carbon fiber

Reinforcedplastic

Aluminumalloys

Ti and Mgalloys

Low cost but Heavy. LessCorrosionresistance

Light and strong. ButCannot be

shaped

Very light and strong. No corrosion.

Very expensive

Light, moderatelyStrong. Corrosion

Resistance.expensive

Slightly betterThan Al

alloys. But muchexpensive

Cost important? Select steelProperties important? Select CFRP

Future Trends• Metallic Materials

Production follows US economy closely. Alloys may be improved by better

chemistry and process control. New aerospace alloys being constantly

researched.o Aim: To improve temperature and corrosion

resistance.o Example: Nickel based high temperature

super alloys. New processing techniques are

investigated.o Aim: To improve product life and fatigue

properties.o Example: Isothermal forging, Powder

metallurgy. Metals for biomedical applications

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Future Trends

• Polymeric (Plastic Materials) Fastest growing basic material (9%

per year). After 1995 growth rate decreased

due to saturation. Different polymeric materials can

be blend together to produce new plastic alloys.

Search for new plastic continues.

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Future Trends

• Ceramic MaterialsNew family of engineering ceramics are

produced last decade New materials and applications are constantly

found. Now used in Auto and Biomedical

applications. Processing of ceramics is expensive. Easily damaged as they are highly brittle. Better processing techniques and high-impact

ceramics are to be found.

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Future Trends

• Composite Materials Fiber reinforced plastics are primary

products. On an average 3% annual growth from

1981 to 1987. Annual growth rate of 5% is predicted

for new composites such as Fiberglass-Epoxy and Graphite-Epoxy combinations.

Commercial aircrafts are expected to use more and more composite materials.

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Future Trends

• Electronic Materials Use of electronic materials such as

silicon increased rapidly from 1970. Electronic materials are expected to play

vital role in “Factories of Future”. Use of computers and robots will

increase resulting in extensive growth in use of electronic materials.

Aluminum for interconnections in integrated circuits might be replaced by copper resulting in better conductivity.

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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.

MEMS and Nanomaterials• 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.