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  1. 1. Material Science Composites By Yokesh D 3rd Yr . BE EEE SW PSG College of Technology Coimbatore – 641 004
  2. 2. COMPOSITES Classification based on Matrices
  3. 3. What are composites?
  4. 4. A Composite material is a material made from two or more constituent materials with significantly different physical or chemical properties that, when combined, produce a material with characteristics different from the individual components (or) Artificially produced multiphase materials (or) Design materials with properties better than those of conventional materials
  5. 5. In their broadest form, composites are materials consist of two or more constituents. The constituents are combined in such a way that they keep their individual physical phases and are not soluble in each other or not to form a new chemical compound.
  6. 6. There are two main categories of constituent materials: 1. Reinforcing phase(Fibres, sheets, or particles, embedded in the matrix) 2. Matrix phase(binder) The reinforcing material and the matrix material can be metal, ceramic, or polymer. Reinforcement Matrix Composites
  7. 7. Matrix • 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, shares the load with the secondary phase • Determine inter-laminar shear strength, damage tolerance, in-plane shear strength, processing capacity , heat resistance of composites.
  8. 8. Reinforcement The reinforcements impart their special mechanical and physical properties to enhance the matrix properties. (A black carbon fiber used as reinforcement compared with human hair)
  9. 9. Why Composites: • The new material may be preferred for many reasons:  stronger,  lighter,  less expensive when compared to traditional materials • The properties and performance of composites are far superior to those of the constituents
  10. 10. History
  11. 11. Composites have played an important role throughout human history • Plywood - 3400 BC by the Ancient Mesopotamians; gluing wood at different angles gives better properties than natural wood • Concrete was described by Vitruvius, writing around 25 BC in his Ten Books on Architecture • Cartonnage layers of linen or papyrus soaked in plaster dates to the First Intermediate Period of Egypt c. 2181–2055 BC and was used for death masks
  12. 12. • Cob (material) Mud Bricks, or Mud Walls, (using mud (clay) with straw or gravel as a binder), used for thousands of years. • In the 12th century A.D., Mongol warriors used composite materials (bamboo, silk, cattle tendons and horns, and pine resin) to craft Archery bows that were swifter and more powerful than those of their rivals • Papier-mâché, a composite of paper and glue, has been used for hundreds of years • The first artificial fibre reinforced plastic was Bakelite which dates to 1907 Now a days composites are used mostly everywhere.
  13. 13. Classification of composites
  14. 14. Composite materials are commonly classified at following two distinct levels: 1. The first level of classification: is usually made with respect to the matrix constituent 2. The second level of classification: made with respect to geometry of reinforcement
  15. 15. I. Based on Matrices
  16. 16. II. Based on geometry of reinforcements 1.Fiber reinforced composites 2.Laminar composites 3.Particulate composites
  17. 17. Let us see in brief about various types of reinforced composites
  18. 18. 1.Fiber reinforced composites A fibre-reinforced composite (FRC) is a composite building material that consists of three components: (i)the fibers as the discontinuous or dispersed phase, (ii)the matrix as the continuous phase, and (iii)the fine interphase region, also known as the interface.
  19. 19. Fiber reinforced composites
  20. 20. Microscopic view of fiber reinforced composties Scanning electron micro-graphs of various fiber architectures. a) woven polyethylene fibers; b) braided glass fibers; c) woven (bidirectional) glass fibers; d) unidirectional glass fibers
  21. 21. Laminar composites • a composite laminates is an assembly of layers of fibrous composite materials which can be joined to provide required engineering pro perties, including in-plane stiffness, bending stiffness, strength, and coefficient of thermal expansion.
  22. 22. Particulate composites • They are composed of particles distributed or embedded in a matrix body. • The particles may be flakes or in powder form. • Concrete and wood particle boards are examples of this category.
  23. 23. • Now, let us see in detail about the classification of composites based on composite matrices
  24. 24. Classification based on Matrices
  25. 25. Based on Matrix
  26. 26. Composites Organic Matrix Composites (OMC) Polymer Matrix Composites Thermoset Thermoplastic Rubber Carbon Matrix Composites Metal Matrix Composites (MMC) Ceramic Matrix Composites (CMC)
  27. 27. Organic Matrix Composites
  28. 28. Organic Matrix Composites(OMC) • In this the matrix material is an Organic compound • Eg: Asphalt concrete, Dental composite, Syntactic foam • The Matrix is made up of either a Polymer or Carbon or both. • Thus it is subdivided into two categories: a. Polymer matrix Composites and b. Carbon matrix composites
  29. 29. a. Polymer Matrix Composites(PMC) • It consists of a Polymer (Resin) Matrix combined with the reinforcing dispersed phase. • Polymer Matrix Composites are very popular due to their low cost and simple fabrication methods • Thus, they are the most widely used composites than any other type.
  30. 30. • There are two main types of PMC’s: i. Thermosets and ii. Thermoplastics
  31. 31. i. Thermosets • Thermosets have qualities such as a well-bonded three-dimensional molecular structure after curing. • Changing the basic composition of the resin is enough to alter the conditions suitably for curing and determine its other characteristics. • They can be retained in a partially cured condition too over prolonged periods of time, rendering Thermosets very flexible. • Thus, they are most suited as matrix bases for advanced conditions fibre reinforced composites
  32. 32. Thermosets Thermosetting polymer Glass fibers in Thermosetting polymer matrix(TEM image)
  33. 33. ii. Thermoplastics • Thermoplastics have one- or two-dimensional molecular structure and they tend to at an elevated temperature and show exaggerated melting point. • Another advantage is that the process of softening at elevated temperatures can reversed to regain its properties during cooling, facilitating applications of conventional compress techniques to mould the compounds.
  34. 34. SEM images of Thermoplastic polymer matrix microstructure
  35. 35. • Resins reinforced with thermoplastics now comprised an emerging group of composites. • The theme of most experiments in this area to improve the base properties of the resins and extract the greatest functional advantages from them in new avenues, including attempts to replace metals in die-casting processes
  36. 36. b. Carbon Matrix Composites • They are combination of carbon-fibre reinforcement in an all carbon matrix • Light weight and exceptional strength due to stiffness of carbon fibres • Their dimensional stability, laser hardness, and low outgassing also make them ideal candidates for various space structural applications. • Material of choice for severe-environment applications
  37. 37. b. Carbon Matrix Composites • Developed specifically for parts that must operate in extreme temperature ranges. • Composed of a carbon matrix reinforced with carbon yarn fabric, 3-D woven fabric, 3-D braiding, etc. • Extremely high temperature resistance (1930°C – 2760°C) • Strength actually increases at higher temperatures (up to 1930°C).
  38. 38. Carbon matrix composites
  39. 39. Metal Matrix Composites
  40. 40. Metallic Matrix Composites(MMC) • MMCs are advanced class of structural materials consisting of non-metallic reinforcements incorporated into the metallic matrix. • MMCs are widely used in engineering applications where the operating temperature lies in between 250 ºC to 750 ºC. • High strength, fracture toughness and stiffness are offered by metal matrices than other composites
  41. 41. • They can withstand elevated temperature in corrosive environment than polymer composites • Most metals and alloys could be used as matrices • Require reinforcement materials which need to be stable over a range of temperature and non-reactive • Generating a wide interest in research fraternity, are not as widely in use as their plastic counterparts • Examples: i. White cast iron ii. Hardmetal (carbide in metal matrix) iii. Metal-intermetallic laminate
  42. 42. • Matrix materials: Aluminium, Titanium, Copper, Magnesium and Super alloys. • Reinforcement materials: Silicon carbide, Boron, Molybdenum and Alumina Titanium, Aluminium and magnesium are the popular matrix metals currently in vogue, which are particularly useful for aircraft applications.
  43. 43. MMC Microstructures (Mono filaments)
  44. 44. MMC Microstructures (Whiskers/short fibers)
  45. 45. MMC Microstructures (Particles)
  46. 46. MMC - disadvantages • Metal matrices are poor in chemical and mechanical compatibility with the reinforcements. • The chemical inertness of the reinforcement (usually a fibre) at modest resin-fabrication temperatures and large elastic compliance of the matrix are the chemical and mechanical incompatibility problems. • Metal matrix composites are harder to fabricate then the resin-matrix composites.
  47. 47. Ceramic Matrix Composites
  48. 48. Ceramic Matrix Composites(CMC) • Composite materials consisting of a ceramic matrix and one or more additional property-modifying components • Ceramics can be described as solid materials which exhibit very strong ionic bonding in general and in few cases covalent bonding. • High melting points, good corrosion resistance, stability at elevated temperatures and high compressive strength, render ceramic-based matrix materials a favourite for applications requiring a structural material that doesn’t give way at temperatures above 1500ºC.
  49. 49. Crystalline and non crystalline ceramics
  50. 50. Ceramic Matrix Composites(CMC) • Naturally, ceramic matrices are the obvious choice for high temperature applications. • CMCs are commonly reinforced with fiber which adds mechanical strength to the ceramic matrix • Reinforcing fibre composition (carbon, quartz, alumina, etc.) can be selected and tuned based on thermal and electrical needs • Fibre architecture (chopped, woven, braided, etc.) can be tailored to address specific mechanical design criteria
  51. 51. Ceramic Matrix Composites(CMC) • To further refine and enhance performance, particulate fillers such as silicon carbide or zirconia can be added to modify both surface and bulk properties. • Family of materials that can successfully withstand temperatures above that of the most advanced high temperature polymers and metals, while at the same time being resilient to the chipping and shattering associated with common monolithic ceramics. • Examples: i. Bone (hydroxyapatite reinforced with collagen fibres) ii. Cermet (ceramic and metal) iii. Concrete …
  52. 52. Ceramic Matrix Composites(CMC)
  53. 53. Ceramic Matrix Composites
  54. 54. Ceramic Matrix Composites
  55. 55. Ceramic Matrix Composites
  56. 56. Disadvantages of CMC’s The two main reasons for slow adoption of CMCs into both military and industrial applications are • High costs • Long lead times associated with CMC production and machining. Expensive raw materials, manually intensive batch processing and costly fiber interfacing techniques are just a few of the reasons why CMCs are much more expensive than their monolithic counterparts.
  57. 57. Comparison between different composites
  58. 58. Advantages of composites Composites can be very strong and stiff, yet very light in weight, so ratios of strength-to-weight and stiffness-to-weight are several times greater than steel or aluminium. • High specific strength and • High specific stiffness • Long fatigue life • High creep resistance
  59. 59. Advantages of composites • Low coefficient of thermal expansion • Low density • Low thermal conductivity • Better wear resistance • Improved corrosion resistance • Better temperature dependent behaviour
  60. 60. Disadvantages of composites • Anisotropic - this may be an advantage or a disadvantage • Polymer-based composites are subject to attack by chemicals or solvents • Expensive • Manufacturing methods for shaping composite materials are often slow and costly • Compared to metals, composites have relatively poor bearing strength.
  61. 61. Composite failure • Shock, impact, or repeated cyclic stresses can cause the laminate to separate at the interface between two layers, a condition known as delamination. • Individual fibres can separate from the matrix e.g. fibre pull-out. • Failure of a brittle ceramic matrix composite occurred when the carbon-carbon composite tile on the leading edge of the wing of the Space Shuttle Columbia fractured when impacted during take-off
  62. 62. Applications In Aerospace: • Carbon fiber is the most widely used composite fiber in aerospace applications. • Aramid fibers, on the other hand, are widely used for constructing leading and trailing edge wing components and very stiff, very light bulkhead, fuel tanks and floor
  63. 63. Space shuttle • Aluminium and Magnesium metallic composites are used for their light weight • Thermal Protection System(TPS) • Reinforced carbon– carbon (RCC), used in the nose cap, the chin area between the nose cap and nose landing gear doors( 1,260 °C (2,300 °F))
  64. 64. Automobile: • Engines bodies, • Piston, • cylinder, • connecting rod, • crankshafts, • bearing materials, • brake discs etc..
  65. 65. Construction • Concrete is the most common artificial composite material of all and typically consists of loose stones (aggregate) held with a matrix of cement. Inexpensive material, not compress or shatter even under quite a large compressive force • Plywood-A laminar composite • FRP-Fiber reinforced plastics used in Bridge structures
  66. 66. Medical Application • Orthopedic applications: bone fixation plates, hip joint replacement, bone cement, and bone grafts • External Prosthetics • Composite materials are used in clinical practice to restore anterior and posterior teeth. • X ray tables, mammogram sheets etc.…
  67. 67. Other applications • Industry • Marine • Power transmission towers • Military applications • Sports equipments • And many more….
  68. 68. THANK YOU