Composite materials
- 2. The world of materials PE, PP PA (Nylon) Polymers, elastomers Butyl rubber Neoprene Polymer foams Metal foams Foams Ceramic foams Glass foams Woods Natural materials Natural fibres: Hemp, Flax, Cotton GFRP CFRP Composites KFRP Plywood Alumina Si-Carbide Ceramics, glasses Soda-glass Steels Cast irons Al-alloys Metals Cu-alloys Ni-alloys Ti-alloys 2
- 3. Definition • A broad definition of composite is: Two or more chemically distinct materials which when combined have improved properties over the individual materials. • The constituents retain their identities in the composite; that is, they do not dissolve or otherwise merge completely into each other, although they act in concert. 3
- 4. Advantages of Composites • Light in weight • Strength-to-weight and Stiffness-to-weight are greater than steel or aluminum • Fatigue properties are better than common engineering metals • Composites cannot corrode like steel • Possible to achieve combinations of properties not attainable with metals, ceramics, or polymers alone 4
- 5. Components in a Composite Material • Nearly all composite materials consist of two phases: 1. Primary phase - forms the matrix within which the secondary phase is imbedded 1. Secondary phase - imbedded phase sometimes referred to as a reinforcing agent, because it usually serves to strengthen the composite • The reinforcing phase may be in the form of fibers, particles, or various other geometries 5
- 6. Functions of the Matrix Material (Primary Phase) • Provides the bulk form of the part or product made of the composite material • Holds the imbedded phase in place, usually enclosing and often concealing it • When a load is applied, the matrix shares the load with the secondary phase, in some cases deforming so that the stress is essentially born by the reinforcing agent 6
- 7. The Reinforcing Phase (Secondary Phase) • Function is to reinforce the primary phase • Imbedded phase is most commonly one of the following shapes: – Fibers – Particles – Flakes 7
- 8. Factors in Creating Composites Matrix material Reinforcement material – Concentration – Size – Shape – Distribution – Orientation 8
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- 10. Classification Large- particle Dispersion- strengthened Particle-reinforced Continuous (aligned) Aligned Randomly oriented Discontinuous (short) Fiber-reinforced Laminates Sandwich panels Structural Composites Based on type of reinforcement 10
- 11. Large particle reinforced composites • Particle size is 1-50µm • Concentration usually ranges from 15-40% by volume • The particulate phase is harder and stiffer than the matrix. • Particles provide strength to the composite by restraining the movement of the matrix • Cermets-tungsten carbide or titanium carbide • Vulcanized rubber- carbon black in rubber • Concrete- sand and gravel particulate in a surry of cement matrix. 11
- 12. Dispersion strengthened composites • Uniformly dispersed fine, hard and inert particles of size less than 0.1µm are used as reinforcement • The volume fraction is between 5-15% • These particles are stronger than the pure metal matrix and can be metallic, inter-metallic or nonmetallic. • Matrix is the load bearing phase • Eg. SAP, TD-Nickel, Cu-Al2O3, Cu-Zn-Al2O3 12
- 13. Particules as the reinforcement (Particulate composites) 13
- 14. Fillers as the reinforcement (Filler composites) 14
- 15. Fibre Reinforced Composites(FRP) 1. Continuous fibre reinforced composites 2. Discontinuous fibre reinforced composites 15
- 16. Random fiber (short fiber) reinforced composites 16
- 17. Continuous fiber (long fiber) reinforced composites 17
- 18. Typical Reinforcement Geometries for Composites 18
- 19. OTHER COMPOSITE STRUCTURES Laminar composite structure :- Two or more layers bonded together in an integral piece Sandwich structure:- foam & honey cores Consists of a thick core of low density foam bonded on both faces to thin sheets of a different material 19
- 20. Classification based on Matrices Composite materials Matrices Polymer Matrix Composites (PMC) Metal Matrix Composites MMC) Ceramic Matrix Composites (CMC) Thermoset Thermoplastic Rubber 20
- 21. Role of matrix phase • Primary function of the matrix phase in a composite is to hold and bind the reinforcing phase in position within it • Act as a medium through which the external load is transmitted and distributed to the reinforcing phase. • It separates fibres from each other • Protects the individual fibres from surface damage due to abrasion and oxidation • Improves fracture toughness of the composite • Withstand heat or cold, conduct or resist electricity, control chemical attack 21
- 22. Polymer Matrix Composites In PMCs polymer is the primary phase in which a secondary phase is imbedded as fibers, particles, or flakes • Commercially, PMCs are more important than MMCs or CMCs • Low density, high specific strength, high specific stiffness, ease of fabrication. • Examples: Rubber reinforced with carbon black and fiber-reinforced pastic (FRPs) 22
- 23. MATRIX & REINFORCEMENT MATRIX • Thermosetting polymers are the most common matrix materials – Principal TS polymers are: • Phenolics – used with particulate reinforcing phases • Polyesters and epoxies - most closely associated with FRPs • Nearly all rubbers are reinforced with carbon black REINFORCEMENT • Possible geometries - (a) fibers, (b) particles & (c) flakes • Particles and flakes are used in many plastic molding compounds • Of most engineering interest is the use of fibers as the reinforcing phase in FRPs 23
- 24. Glass fibre reinforced polymer composites • Contains glass fibre as reinforcing phase in a polymer matrix • Glass fiber • Continuous or discontinuous • Dia b/w 3-20μm • Lim: not very stiff and rigid • Automobile and marine bodies, storage containers, plastic pipes, industrial flooring 24
- 25. Carbon fibre reinforced polymer composites • Contains carbon fibre as reinforcing phase in a polymer matrix • Advantages • High specific strength and specific modulus • Higher strength at elevated temperatures • Not affected by moisture or acids • Applications • Aerospace application • Sports and recreational equipments • Pressure vessels 25
- 26. Aramid fibre reinforced polymer composites • Aramid-polyamide-kevlar or nomex • Advantages • High toughness and impact resistance • Resistance to creep and fatigue failure • Applications • Bullet proof vests and armor • Sports goods, missile cases • Pressure vessels, clutch linings and gaskets 26
- 27. Metal matrix composites • Metals with low density and low temperature toughness are preferred as matrix metal. • Aluminium, titanium, magnesium and their alloys • Advantages • Higher operating temperatures • Non flammability and creep resistance • Greater resistance to degradation by organic fluids. • Applications • Aerospace application • Gas turbine blades • Electrical contacts 27
- 28. Ceramic Matrix Composites • Primary objective for developing CMCs was to enhance the toughness while retaining the high temperature properties. • High melting points and good resistance to oxidation • But low tensile strength, impact resistant and shock resistance • eg. Small particles of partially stabilized Zirconia are dispersed within a matrix material Al2O3 28
- 29. Hybrid composites • Obtained by using different kinds of fibers in a single 29
- 30. Applications 1. Aircraft and aerospace applications 2. Automotive applications 3. Marine applications 4. Sporting industries 5. Biomaterials 6. Industrial applications 30
- 31. Lower Drag Brace for the F16 Lower Drag Brace of F16: Landing gear Titanium Matrix Composite Monofilament SiC fibres in a Ti-matrix. 31
- 32. Lightweight Composite Core for Power Lines Lightweight Aluminum Conductor Composite Core (ACCC) o Composite Technology Corporation (CTC) o Twice the amount of electric power as conventional power lines. 32
- 33. Brake rotors for high speed train Brake rotors for high speed train • particulate reinforced Aluminium alloy (AlSi7Mg+SiC particulates) • Weight of cast iron rotor is 120 kg/piece while MMC it is 76 kg/piece 33
- 34. Cylinder liner Boxter engine block Cylinder liner AlSi9Cu3 alloy with 25% Si. Squeeze casting infiltration 34
- 35. F-16 Fuel Access Door Covers • High specific strength and stiffness good bearing strength • Al Composites • 6092/SiC/17.5p • Wrought P/M material • Elimination of the skin cracking problem 35
- 36. F-16 Ventral Fins • High specific stiffness and strength • Al-matrix composites • Rolled P/M • 6092/SiC/17.5p • Decreased deflections provide an increase in fin life 36
- 37. Recreational products Skating shoe Base ball shafts Horse shoes Bicycle Frames 37
- 38. Space Shuttle • Mid fuselage frames of Space Shuttle was made of MMCs 38
- 39. Common MMCs and Applications 39
- 40. Metal Matrix Automotive Brake Caliper Aluminum-matrix composite brake caliper using nanocrystallyne alumina fiber reinforcement. 40
- 41. Application of advanced composite materials in Boeing 757-200 commercial aircraft. Source: Courtesy of Boeing Commercial Airplane Company. 41
- 42. Boeing C-17 Globemaster III (large military transport aircraft) 42
- 43. Cross-section of a composite sailboard. Source: K. Easterline, Tomorrow’s Materials (2nd ed.), p. 133. Institute of Metals, 1990. 43
- 45. Wing Panel Aerospace parts Automotive structure 45
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- 48. Disadvantages and Limitations of Composite Materials • Properties of many important composites are anisotropic - the properties differ depending on the direction in which they are measured – this may be an advantage or a disadvantage • Many of the polymer-based composites are subject to attack by chemicals or solvents, just as the polymers themselves are susceptible to attack • Composite materials are generally expensive • Manufacturing methods for shaping composite materials are often slow and costly 48