Composite Material-converted.docx

COMPOSITE MATERIAL

A combination of two or more materials to form a new material system with enhanced material properties

Reinforcement

+

Matrix

=

Composite

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WHAT ARE COMPOSITES? Composites: A combination of two or more materials (reinforcement, resin, filler, etc.), differing in form or composition on a macroscale. The constituents retain their identities, i.e.., they do not dissolve or merge into each other, although they act in concert. Normally, the components can be physically identified and exhibit an interface between each other.

Composites: Design materials with properties better than those of conventional materials (metals, ceramics, or polymers). Composites: are combinations of two materials in which one of the materials, called the reinforcing phase, is in the form of fibers, sheets, or particles, and is embedded in the other materials called the matrix phase. The reinforcing material and the matrix material can be metal, ceramic, or polymer. 2

PHASES OF COMPOSITES  Matrix Phase: Polymers, Metals, Ceramics Also, continuous phase, surrounds other phase (e.g.: metal, ceramic, or polymer)  Reinforcement Phase: Fibers, Particles, or Flakes Also, dispersed phase, discontinuous phase (e.g.: metal, ceramic, or polymer)

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FACTORS IN CREATING COMPOSITES  Factors in creating composites: – Matrix material – Reinforcement material

 → control

or design properties

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CLASSIFICATION OF COMPOSITES 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. The major composite classes include Organic Matrix Composites (OMCs), Metal Matrix Composites (MMCs) and Ceramic Matrix Composites (CMCs). The term organic matrix composite is generally assumed to include two classes of composites, namely Polymer Matrix Composites (PMCs) and carbon matrix composites commonly referred to as carbon-carbon composites. 2. The second level of classification: refers to the reinforcement form - fibre reinforced composites, laminar composites and particulate composites. Fibre reinforced composites can be further divided into those containing discontinuous or continuous fibres. 5

CLASSIFICATION BASED ON MATRIX PHASE

The matrix phase of fibrous composites may be a metal, polymer, or ceramic. In general, metals and polymers are used as matrix materials because some ductility is desirable; for ceramic-matrix composites the reinforcing component is added to improve fracture toughness Polymer Matrix Composites (PMC)/Carbon Matrix Composites or Carbon- Carbon Composites Matrix Composites (MMC) 6

Ceramic Matrix Materials (CMM)

1.ROLE OF MATRIX Role of Matrices in Composites  Transfer stresses between the fibers.  Provide a barrier against an adverse environment.  Protect the surface of the fibers from mechanical abrasion.  Determine inter-laminar shear strength.  Determine damage tolerance of composites.  Determine in-plane shear strength.  Determine the processibility of composites.  Determine heat resistance of composites.

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2.ROLE OF MATRIX  The primary roles of the matrix alloy then are to provide efficient transfer of load to the fibers and to blunt cracks in the event that fiber failure occurs and so the matrix alloy for continuously reinforced composites may be chosen more for toughness than for strength.  On this basis, lower strength, more ductile, and tougher matrix alloys may be utilized in continuously reinforced composites.  For discontinuously reinforced composites, the matrix may govern composite strength. Then, the choice of matrix will be influenced by consideration of the required composite strength and higher strength matrix alloys may be required. 8

FUNCTIONS OF MATRIX In a composite material, the matrix material serves the following functions:  Holds the fibres together.  Protects the fibres from environment.  Distributes the loads evenly between fibres so that all fibres are subjected to the same amount of strain.  Enhances transverse properties of a laminate.  Improves impact and fracture resistance of a component.  Helps to avoid propagation of crack growth through the fibres by providing alternate failure path along the interface between the fibres and the matrix.  Carry interlaminar shear. 9

POLYMER MATRIX COMPOSITES (PMC)/CARBON MATRIX COMPOSITES  Polymer-matrix composites (PMCs) consist of a polymer resin as the matrix, with fibers as the reinforcement medium.  Fiber reinforced polymers (FRP) – Fibers (carbon or glass) – Resins (epoxy matrix)

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METAL-MATRIX COMPOSITES  As the name implies, for metal-matrix composites (MMCs) the matrix is a ductile metal. These materials may be utilized at higher service temperatures than their base metal counterparts; furthermore, the reinforcement may improve specific stiffness, specific strength, abrasion resistance, creep resistance, thermal conductivity, and dimensional stability

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CERAMIC-MATRIX COMPOSITES  The fracture toughness of ceramics have been improved significantly by the development of a new generation of ceramic-matrix composites (CMCs) — particulates, fibers, or whiskers of one ceramic material that have been embedded into a matrix of another ceramic. Ceramic-matrix composite materials have extended fracture toughness to between about 6 and 20 MPa

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CLASSIFICATION BASED ON REINFORCEMENTS

 Fiber Reinforced Composites/Fibre Reinforced Polymer (FRP) Composites  Laminar Composites  Particulate Reinforced Composites (PRC)

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FIBER REINFORCED COMPOSITES/FIBRE REINFORCED POLYMER (FRP) COMPOSITES  Fibre Reinforced Composites are composed of fibres embedded in matrix material.  Fiber Reinforced Polymer (FRP) Composites: "A matrix of polymeric material that is reinforced by fibers or other reinforcing material”

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GLASS FIBER-REINFORCED POLYMER (GFRP) COMPOSITES  Fiberglass is simply a composite consisting of glass fibers, either continuous or discontinuous, contained within a polymer matrix

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CARBON FIBER-REINFORCED POLYMER (CFRP) COMPOSITES  Carbon is a high-performance fiber material that is the most commonly used reinforcement in advanced (nonfiberglass) polymer-matrix composites

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ARAMID FIBER-REINFORCED POLYMER COMPOSITES  Aramid fibers are high-strength, highmodulus materials that were introduced in the early 1970s. They are especially desirable for their outstanding strength-to weight ratios, which are superior to metals.

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CARBON–CARBON COMPOSITES  One of the most advanced and promising engineering material is the carbon fiber reinforced carbon-matrix composite, often termed a carbon–carbon composite; as the name implies, both reinforcement and matrix are carbon.

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HYBRID COMPOSITES  A relatively new fiber-reinforced composite is the hybrid, which is obtained by using two or more different kinds of fibers in a single matrix; hybrids have a better all around combination of properties than composites containing only a single fiber type.

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PARTICLE-REINFORCED COMPOSITES  Particulate Composites: 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.  Large-particle and dispersionstrengthened composites are the two sub classifications of particle-reinforced composites.

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LARGE-PARTICLE AND DISPERSIONSTRENGTHENED COMPOSITES  Concrete is a common large-particle composite in which both matrix and dispersed phases are ceramic materials.  Metals and metal alloys may be strengthened and hardened by the uniform dispersion of several volume percent of fine particles of a very hard and inert material. The dispersed phase may be metallic or nonmetallic; oxide materials are often used

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LAMINAR COMPOSITES  A laminar composite is composed of twodimensional sheets or panels that have a preferred high-strength direction such as is found in wood and continuous and aligned fiber-reinforced plastics

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COMMON CATEGORIES OF COMPOSITE MATERIALS BASED ON FIBRE LENGTH 1.

Fibers as the reinforcement (Fibrous Composites): a. Random fiber (short fiber) reinforced composites b. Continuous fiber (long fiber) reinforced composites

2.

Particles as the reinforcement (Particulate composites):

3.

Flat flakes as the reinforcement (Flake composites):

4.

Fillers as the reinforcement (Filler composites):

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CONTINUED……

1.

Fibers as the reinforcement (Fibrous Composites): a. Random fiber (short fiber) reinforced composites

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CONTINUED…… 1.

Fibers as the reinforcement (Fibrous Composites): b. Continuous fiber (long fiber) reinforced composites

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CONTINUOUS COMPOS ITE

Discontinuous Composite

Matrix (binder)

Reinforcement (fiber)

Aligned (random)

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Continued…… 2. Particles as the reinforcement (Particulate composites):

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Continued…… 3. Flat flakes as the reinforcement (Flake composites):

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Continued…… 4. Fillers as the reinforcement (Filler composites):

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WHY COMPOSITES?

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