11 Composites 2 130212 Engineering materials Assistant Professor

บทท 11 วสดรวม Composites 2 130212 Engineering materials Assistant Professor Sukangkana Lee 1

Electric Mobility Cart Body: fiber glass Windshield: laminated glass Ceiling: fiber glass ceiling, Seats: soft seat and softened arm seat Floor: leather Instrument panel: fiber glass, www. impexol. cn/2005/1 -15/08530234967. html 4

�������� matrix 1. Metal Matrix Composites (MMC) MMC are composed of a metallic matrix (aluminum, magnesium, iron, cobalt, copper) and a dispersed ceramic (oxides, carbides) or metallic (lead, tungsten, molybdenum) phase. 2. Ceramic Matrix Composites (CMC) CMC are composed of a ceramic matrix and embedded fibers of other ceramic material (dispersed phase). 3. Polymer Matrix Composites (PMC) PMC are composed of a matrix from thermoseting (Unsaturated Polyester (UP), Epoxiy (EP)) or thermoplastic (Polycarbonate (PC), Polyvinylchloride, Nylon, Polysterene) and embedded glass, carbon, steel or Kevlar fibers (dispersed phase). 9

Classification of Composite 1. Particle-Reinforces Composite 2. Fibrous Composite Matrix Particles วสดเสรมสามารถมไดหลายรปราง Fiber Matrix และหลายขนาด เชน 10

3. Other Composite Structures (a) Conventional Laminar Composite Structure (b) Sandwich Structure – Foam Core (c) Sandwich structure using honeycomb core 11

Carbon Fiber Glass Fiber 14

Multilayered composite 3 -D weave for fiberreinforced composite 15

Advantages 1. 2. 3. 4. 5. 6. 7. 8. lightweight The fiber/resin mix can be customized to meet stiffness, strength and manufacturing requirements Part consolidation means a reduced number of assemblies and a reduced fastener count Reduced machining Tapered sections and compound contours easily accomplished Resistant to corrosion Resistant to fatigue damage with good damping characteristics Low coefficient of thermal expansion 16

disadvantages l l Complex manufacturing process Some part are cost consumption No able to recycle Difficult to repair or replacement 17

Strength of Continuous Composites po s Co m Stress ite Fiber Fracture Matrix Fracture Strain 19

. 4 The pultrusion process การดงเสน ใยผานอางพลาสตกเหลว เปนการผลต Fiber-reinforced plastic composite materials 27

Power cable PE Cu PVC 29

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Metal metrix composite MMC are composed of a metallic matrix (aluminum, magnesium, iron, cobalt, copper) and a dispersed ceramic (oxides, carbides) or metallic (lead, tungsten, molybdenum) phase. l D: Documentsweb 1302 212Metal matrix composites. mht 33

Plastic matrix composite PMC are composed of a matrix from thermoseting (Unsaturated Polyester (UP), Epoxiy (EP)) or thermoplastic (Polycarbonate (PC), Polyvinylchloride, Nylon, Polysterene) and embedded glass, carbon, steel or Kevlar fibers (dispersed phase). 34

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Ceramic matrix composite CMC are composed of a ceramic matrix and embedded fibers of other ceramic material (dispersed phase). แทนเจาะนำมนม ฐานเปนคอนกรตเสรมเหลก 37

What is Concrete? Concrete is basically a mixture of two components: 1. Aggregates 2. Paste (or binder) 38

Hydration of cement l ‘Hydration’ is the chemical reaction of the cementitious materials and water. l The result is the paste become solid and bind the aggregates. l ซเมนตกบนำ จะทำปฏกรยาอยางชาๆ จากผวนอกสดานใน ถาไดรบนำอยางตอเนอง เชน 39

Hydration + + + + 1. Unhydrated cement&water 2. Hydrated cement containing capillary pores ++ ++ ++ + + + 3. Extra water filled pores + ++ + + + ++ + ++ ++ + 4. Cement completely hydrated 40

Cement process 1. Quarry 2. Crusher 3. Conveyor 6. Filter bag 7. Preheater 8. Kiln : 1000 -2000 C 4. Mixing bed 9. Cooler 5. Raw mill 10. Clinker silo 11. Cement mill 12. Logistics 45

Cement process l l animation : How we make cement http: //www. essroc. com/default. aspx? pageid= 183 46

Types of Cements 1. Portland Cements: is a hydraulic cement which means that it sets and hardens due to a chemical reaction with water. Consequently, it will harden under water. สวนประกอบหลก คอ Lime-Ca. CO 3 (calcium carbonate) หรอปนขาว ซงทมขายในทองตลาดอยในรปของผงสขา ว l Si. O 2 (Silica) l Al 2 O 3 (Alumina) l Fe 2 O 3 (Ferrite) l 48

2. Blended hydraulic cement contains additional ingredients, such as fly ash, or blast furnace slag directly in the cement. Presently, most concrete for use in pavement is made with a portland cement, but use of blended hydraulic cements appears to be increasing. 50

สวนผสมของ Concrete l Cement paste: 25% to 40% (Cement 7% -15%, water 14% - 21%) l Aggregates: 60% to 75% l Air content: up to about 8% 51

Concrete Quality The quality of any concrete is dependent upon the water-cement ratio or water-cementitious ratio). Water-cement ratio Strength 0. 4 0. 6 0. 8 High Medium Low In general, concrete with a lower watercementitious ratio is stronger and less permeable, thus more durable. 52

Entrained air VS Entrapped air l. Entrained air: the tiny microscopic air bubbles, provide free space within the paste to relieve hydraulic pressure when concrete freezes preventing cracking. 54

l. Entrapped air: air that gets trapped in the concrete during mixing and are much larger than entrained air bubbles. Any concrete with a large number of entrapped air voids will probably have lower strength and durability. 55

Strength 1. Compressive strength : the compressing force necessary to break the concrete divided by the contact area of the specimen www. mtc-inc. net www. bam. de/div-71. htm 57

www. superformicf. ca/concretestrength. ht m 1. 2. Concrete continues to gain strength with age. The strength used in designing and specifying concrete is measured at 28 days. 58

grade Applications Most concrete compressive strength (psi) 3000 to 5000 paving 6000 Road, floor High-strength 20, 000 Building, bridge general 59

2. Flexural strength: is the strength of concrete to bending. l In designing concrete pavements, flexural strength is often used because it better simulates what happens when a slab is loaded by vehicles. l Most general-use concrete has a flexural strength between 500 psi to 700 psi. 60

http: //www. lflassociates. com/content/philosophy. html 61

Fibre Reinforced Polymer (FRP ( Mithila Achintha and Chris Burgoyne www-civ. eng. cam. ac. uk/cjb/frpdebond/index. html 71

บตทางไฟฟาและสารกงตวนำ บทท 12 Electrical Properties of Materials and semiconductor 2 130212 Engineering materials Assistant Professor Sukangkana Lee 72

Material Metals Ag Cu Au Al Semiconductors Ge Si Insulators Diamond Mica Electrical resistivity ( m) 1. 61 10 -8 1. 69 10 -8 2. 26 10 -8 2. 83 10 -8 Electrical conductivity ( -1 m-1) 6. 2 107 5. 92 107 4. 44 107 3. 57 107 0. 47 3 103 2. 1 3 10 -4 1 1014 9 1014 1 10 -14 1 10 -15 79

Energy band gap Equilibrium Interatomic spacing ระยะหางระหวางอะต อม The electron energy band structure for a solid material 87 at the equilibrium interatomic separation.

ม 4 valence electrons Si Lattice 90

ประเภทของ Semiconductor ม 2 ประเภท คอ 1. Intrinsic semiconductor 2. Extrinsic semiconductor 91

Ge crystal lattice Ge crystal structure at T= 0 K ไมนำไฟฟา e- Hole + T> 0 K ม thermal excite e- กระโดดขาม gap at T > 0 K นำไฟฟาได 94

The Czochralski process The growth of a large (10 or more inches in diameter!) single crystal of silicon. l In this process, a solid seed crystal is rotated and slowly extracted from a pool of molten Si. l 96

Extrinsic semiconductors มอย ชนดคอ 1. Extrinsic n type (negative) 2. Extrinsic p type (positive) 2 101

VA produce n-type semiconductors by contributing extra electrons. 5 valence electrons 3 valence electrons IIIA produce p-type semiconductors by producing 102 a “hole” or electron deficiency

Extrinsic p type Extra holes in the band gap allow excitation of valence band electrons, leaving mobile holes in the valence band. 104

Multicrystalline silicon 110