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Composite materials basic describing various types
- 1. Composite Materials Ashutosh Pattanaik Asst.Prof CV Raman College of Engineering, Bhubaneswar
- 2. A Compositematerial is a material system composed of two or more macro constituents that differ in shape and chemical composition and which are insoluble in each other. Applications: ◦ Aerospace industry ◦ Sporting Goods Industry ◦ Automotive Industry ◦ Home Appliance Industry Introduction
- 5. High AspectRatio Better Fatigue properties than for engineering metals High Toughness High Corrosion resistance Possible to achieve combinations of properties not attainable with metals, ceramics, or polymers alone Advantages
- 6. Attacked byChemicals like Acid, Base, Acetone etc. Composite materials are generally expensive Low production rate High cost as compared to conventional metals Disadvantages
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- 9. Matrix: The continuousphase Purpose is to: transfer stress to other phases protect phases from environment Classification: MMC, CMC, PMC Reinforcement: Purpose: enhance matrix properties. Classification: Particle, fiber, structural
- 11. Protect phasesfrom environment Transfer Stresses to phases 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 Functions of the Matrix Material
- 12. Concrete – gravel+ sand + cement - Why sand and gravel? Sand packs into gravel voids Reinforced concrete - Reinforce with steel rebar - increases strength - even if cement matrix is cracked Particle-reinforced Fiber-reinforced Structural Reinforcement
- 13. Fibers themselvesare very strong – Provide significant strength improvement to material – Ex: Fiber-glass • Continuous glass filaments in a polymer matrix • Strength due to fibers • Polymer simply holds them in place and environmentally protects them Particle-reinforced Fiber-reinforced Structural
- 14. Fiber Loading Effectunder Stress:
- 15. • Fiber Materials Whiskers - Thin single crystals - large length to diameter ratio • graphite, SiN, SiC • high crystal perfection – extremely strong • very expensive Fibers • polycrystalline or amorphous • generally polymers or ceramics • Ex: Al2O3 , Aramid, E-glass, Boron, UHMWPE Wires • Metal – steel, Mo, W Particle-reinforced Fiber-reinforced Structural
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- 17. Stacked andbonded fiber-reinforced sheets -- stacking sequence: e.g., 0º/90º or 0/45/90º -- benefit: balanced, in-plane stiffness Structural Particle-reinforced Fiber-reinforced Structural Sandwich panels -- low density, honeycomb core -- benefit: light weight, large bending stiffness honeycomb adhesive layer face sheet
- 18. Metal Matrix Composites(MMCs) A metal matrix reinforced by a second phase Reinforcing phases: Particles of ceramic (these MMCs are commonly called cermets) Fibers of various materials: other metals, ceramics, carbon, and boron
- 19. Cermets MMC withceramic contained in a metallic matrix The ceramic often dominates the mixture, sometimes up to 96% by volume Bonding can be enhanced by slight solubility between phases at elevated temperatures used in processing Cermets can be subdivided into Cemented carbides – most common Oxide based cermets – less common ‑
- 20. Cemented Carbides Oneor more carbide compounds bonded in a metallic matrix The term cermet is not used for all of these materials, even though it is technically correct Common cemented carbides are based on tungsten carbide (WC), titanium carbide (TiC), and chromium carbide (Cr3C2) Tantalum carbide (TaC) and others are less common Metallic binders: usually cobalt (Co) or nickel (Ni)
- 21. Applications of CementedCarbides Tungsten carbide cermets (Co binder) - cutting tools are most common; other: wire drawing dies, rock drilling bits and other mining tools, dies for powder metallurgy, indenters for hardness testers Titanium carbide cermets (Ni binder) - high temperature applications such as gas turbine nozzle ‑ vanes, valve seats, thermocouple protection tubes, torch tips, cutting tools for steels Chromium carbides cermets (Ni binder) - gage blocks, valve liners, spray nozzles, bearing seal rings
- 22. Ceramic Matrix Composites(CMCs) A ceramic primary phase imbedded with a secondary phase, which usually consists of fibers Attractive properties of ceramics: high stiffness, hardness, hot hardness, and compressive strength; and relatively low density Weaknesses of ceramics: low toughness and bulk tensile strength, susceptibility to thermal cracking CMCs represent an attempt to retain the desirable properties of ceramics while compensating for their weaknesses
- 23. A polymerprimary phase in which a secondary phase is imbedded as fibers, particles, or flakes Commercially, PMCs are more important than MMCs or CMCs Examples: most plastic molding compounds, rubber reinforced with carbon black, and fiber reinforced polymers (FRPs) ‑ FRPs are most closely identified with the term composite Polymer Matrix Composites (PMCs)
- 24. A PMCconsisting of a polymer matrix imbedded with high ‑ strength fibers Polymer matrix materials: ◦ Usually a thermosetting (TS) plastic such as unsaturated polyester or epoxy ◦ Can also be thermoplastic (TP), such as nylons (polyamides), polycarbonate, polystyrene, and polyvinylchloride ◦ Fiber reinforcement is widely used in rubber products such as tires and conveyor belts Fiber Reinforced Polymers (FRPs) ‑
- 25. Various forms:discontinuous (chopped), continuous, or woven as a fabric Principal fiber materials in FRPs are glass, carbon, and Kevlar 49 Less common fibers include boron, SiC, and Al2O3, and steel Glass (in particular E glass) is the most common fiber ‑ material in today's FRPs; its use to reinforce plastics dates from around 1920 Fibers in PMCs
- 26. Most widelyused form of FRP is a laminar structure, made by stacking and bonding thin layers of fiber and polymer until desired thickness is obtained By varying fiber orientation among layers, a specified level of anisotropy in properties can be achieved in the laminate Applications: parts of thin cross section, such as aircraft ‑ wing and fuselage sections, automobile and truck body panels, and boat hulls Common FRP Structure
- 27. High strengthto weight and modulus to weight ratios ‑ ‑ ‑ ‑ Low specific gravity - a typical FRP weighs only about 1/5 as much as steel; yet, strength and modulus are comparable in fiber direction Good fatigue strength Good corrosion resistance, although polymers are soluble in various chemicals Low thermal expansion - for many FRPs, leading to good dimensional stability FRP Properties
- 28. Aerospace –much of the structural weight of today’s airplanes and helicopters consist of advanced FRPs Automotive – somebody panels for cars and truck cabs ◦ Continued use of low-carbon sheet steel in cars is evidence of its low cost and ease of processing Sports and recreation ◦ Fiberglass reinforced plastic has been used for boat hulls since the 1940s ◦ Fishing rods, tennis rackets, golf club shafts, helmets, skis, bows and arrows. FRPApplications
- 29. In additionto FRPs, other PMCs contain particles, flakes, and short fibers as the secondary phase Called fillers when used in molding compounds Two categories: ◦ Reinforcing fillers – used to strengthen or otherwise improve mechanical properties Examples: wood flour in phenolic and amino resins; and carbon black in rubber ◦ Extenders – used to increase bulk and reduce cost per unit weight, but little or no effect on mechanical properties Other Polymer Matrix Composites
- 30. The twophases are typically produced separately before being combined into the composite part Processing techniques to fabricate MMC and CMC components are similar to those used for powdered metals and ceramics Molding processes are commonly used for PMCs with particles and chopped fibers Specialized processes have been developed for FRPs Processing of Composite Materials
- 31. Composite Manufacturing Processes ParticulateMethods: Powder Metallurgy Route Fiber reinforced: Several Structural: Usually Hand lay-up and atmospheric curing or vacuum curing
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- 33. Hand Lay-Up: Hardeningis at room temperature but may be improved by heating. · Void volume is typically 1%. · Foam cores may be incorporated (and left in the part) for greater shape complexity. Thus essentially all shapes can be produced. · Process is slow (deposition rate around 1 kg/h) and labor- intensive · Quality is highly dependent on operator skill. · Extensively used for products such as airframe components, boats, truck bodies, tanks, swimming pools, and ducts.
- 35. Filament Winding ◦Ex: pressure tanks ◦ Continuous filaments wound onto mandrel
- 36. Pultrusion ◦ Continuous fiberspulled through resin tank, then preforming die & oven to cure
- 37. • Composites areclassified according to: -- the matrix material (CMC, MMC, PMC) -- the reinforcement geometry (particles, fibers, layers). • Particulate-reinforced: -- Elastic modulus can be estimated. -- Properties are isotropic. • Fiber-reinforced: -- Elastic modulus and TS can be estimated along fiber dir. -- Properties can be isotropic or anisotropic. • Structural: -- Based on build-up of sandwiches in layered form. Summary