MODERN ENGINEERING MATERIALS

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MODERN ENGINEERING MATERIALS AND THEIR APPLICATIONS

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MODERN ENGINEERING MATERIALS AND THEIR APPLICATIONS:

MODERN ENGINEERING MATERIALS AND THEIR APPLICATIONS

ABSTRACT:

ABSTRACT Advanced Composite Materials Advance Engineering Materials and their manufacturing is going to play a predominant role in industrial revolution of 21st century .Materials can be broadly classified as Polymer, Metal and Ceramics, as they find wide array of application, starting from automotive, electronic , biomedical, pharmaceutical , construction, aerospace sector to defense ,technical textiles and sports. This paper reviews the analysis of , the advancement in manufacturing process , properties of carbon fibers and along with their high end application …..

INTRODUCTION :

INTRODUCTION Materials science is an interdisciplinary field involving the properties of matter and its applications to various areas of science and engineering. This scientific field investigates the relationship between the structure of materials at atomic or molecular scales and their macroscopic properties Materials science also deals with fundamental properties and characteristics of materials It is also an important part of forensic engineering and failure analysis In materials science, rather than haphazardly looking for and discovering materials and exploiting their properties, the aim is instead to understand materials so that new materials with the desired properties can be created . The basis of materials science involves relating the desired properties and relative performance of a material in a certain application to the structure of the atoms. The major determinants of the structure of a material and thus of its properties are its constituent chemical elements and the way in which it has been processed into its final form. These characteristics, taken together and related through the laws of thermodynamics govern a material’s microstructure, and thus its properties.

Classes of materials :

Classes of materials Ionic crystals Covalent crystals Metals Semiconductors Polymers Composite materials Vitreous materials Plastics

Materials in industry :

Materials in industry Radical materials advances can drive the creation of new products or even new industries, but stable industries also employ materials scientists to make incremental improvements and troubleshoot issues with currently used materials. Industrial applications of materials science include materials design, cost-benefit tradeoffs in industrial production of materials, processing techniques ( casting, rolling, welding, ion implantation , crystal growth, thin-film deposition, sintering, glassblowing, etc.), and analytical techniques (characterization techniques such as electron microscopy, x-ray diffraction, calorimetry , nuclear microscopy (HEFIB), Rutherford backscattering, neutron diffraction, small-angle X-ray scattering (SAXS), etc . Besides material characterization, the material scientist/engineer also deals with the extraction of materials and their conversion into useful forms. Thus ingot casting, foundry techniques, blast furnace extraction, and electrolytic extraction are all part of the required knowledge of a metallurgist/engineer. Often the presence, absence or variation of minute quantities of secondary elements and compounds in a bulk material will have a great impact on the final properties of the materials produced, for instance, steels are classified based on 1/10th and 1/100 weight percentages of the carbon and other alloying elements they contain. Thus, the extraction and purification techniques employed in the extraction of iron in the blast furnace will have an impact of the quality of steel that may be produced.

Materials in industry :

Materials in industry The overlap between physics and materials science has led to the offshoot field of materials physics, which is concerned with the physical properties of materials. The study of metal alloys is a significant part of materials science. Of all the metallic alloys in use today, the alloys of iron ( steel, stainless steel, cast iron, tool steel, alloy steels) make up the largest proportion both by quantity and commercial value. Iron alloyed with various proportions of carbon gives low, mid and high carbon steels. For the steels, the hardness and tensile strength of the steel is directly related to the amount of carbon present, with increasing carbon levels also leading to lower ductility and toughness. The addition of silicon and graphitization will produce cast irons (although some cast irons are made precisely with no graphitization). The addition of chromium, nickel and molybdenum to carbon steels (more than 10%) gives us stainless steels. Other significant metallic alloys are those of aluminium , titanium, copper and magnesium. Copper alloys have been known for a long time (since the Bronze Age), while the alloys of the other three metals have been relatively recently developed. Due to the chemical reactivity of these metals, the electrolytic extraction processes required were only developed relatively recently. The alloys of aluminium , titanium and magnesium are also known and valued for their high strength-to-weight ratios and, in the case of magnesium, their ability to provide electromagnetic shielding. These materials are ideal for situations where high strength-to-weight ratios are more important than bulk cost, such as in the aerospace industry and certain automotive engineering applications.

Materials in industry:

Materials in industry Other than metals, polymers and ceramics are also an important part of materials science. Polymers are the raw materials (the resins) used to make what we commonly call plastics. Plastics are really the final product, created after one or more polymers or additives have been added to a resin during processing, which is then shaped into a final form. Polymers which have been around, and which are in current widespread use, include polyethylene , polypropylene, PVC, polystyrene, nylons, polyesters, acrylics, polyurethanes, and polycarbonates. Plastics are generally classified as "commodity", "specialty" and "engineering" plastics. PVC (polyvinyl-chloride) is widely used, inexpensive, and annual production quantities are large. It lends itself to an incredible array of applications, from artificial leather to electrical insulation and cabling, packaging and containers. Its fabrication and processing are simple and well-established. The versatility of PVC is due to the wide range of plasticisers and other additives that it accepts. The term "additives" in polymer science refers to the chemicals and compounds added to the polymer base to modify its material properties .

Materials in industry:

Materials in industry Polycarbonate would be normally considered an engineering plastic (other examples include PEEK, ABS). Engineering plastics are valued for their superior strengths and other special material properties. They are usually not used for disposable applications, unlike commodity plastics. Specialty plastics are materials with unique characteristics, such as ultra-high strength, electrical conductivity, electro-fluorescence, high thermal stability, etc. The dividing line between the various types of plastics is not based on material but rather on their properties and applications. For instance, polyethylene (PE) is a cheap, low friction polymer commonly used to make disposable shopping bags and trash bags, and is considered a commodity plastic, whereas Medium-Density Polyethylene MDPE is used for underground gas and water pipes, and another variety called Ultra-high Molecular Weight Polyethylene UHMWPE is an engineering plastic which is used extensively as the glide rails for industrial equipment and the low-friction socket in implanted hip joints.

Materials in industry:

Materials in industry Another application of material science in industry is the making of composite materials. Composite materials are structured materials composed of two or more macroscopic phases. Applications range from structural elements such as steel-reinforced concrete, to the thermally insulative tiles which play a key and integral role in NASA's Space Shuttle thermal protection system which is used to protect the surface of the shuttle from the heat of re-entry into the Earth's atmosphere. One example is Reinforced Carbon-Carbon (RCC), The light gray material which withstands reentry temperatures up to 1510 °C (2750 °F) and protects the Space Shuttle's wing leading edges and nose cap.

Materials in industry:

Materials in industry Other examples can be seen in the "plastic" casings of television sets, cell-phones and so on. These plastic casings are usually a composite material made up of a thermoplastic matrix such as acrylonitrile -butadiene-styrene(ABS ) in which calcium carbonate chalk , talc, glass fibres or carbon fibres have been added for added strength, bulk, or electro-static dispersion. These additions may be referred to as reinforcing fibres , or dispersants, depending on their purpose.

Material Selection* :

Material Selection* Failures arising from hasty material selection are not uncommon in any other industry . In an application that demands high-impact resistance, a high-impact material must be specified. If the material is to be used outdoors for a long period, an Ultraviolet resistant (UV) material must be specified. For proper material selection, careful planning, a thorough understanding of materials , and reasonable prototype testing are required.

The Need for Material Selection :

The Need for Material Selection During the last decades many new materials and material types have been developed. At present of the order of 100 000 engineering materials exist. In addition many materials have successively obtained improved properties. This has been possible due to the development of the materials but also due to the appearance of new production methods. As a consequence of this rapid development many material types can be used for a given component. This also applies to situations where one previously only employed one material for example cast iron in cylinder heads where cast aluminium alloys are also used now. Another example is body panels in cars where low carbon mild sheet steel is still the dominating material but many other materials like high strength sheet steels, aluminium alloys, sheet moulding compounds (SMC), thermoplastics, thermoplastic elastomers and expanded plastics are used. In fact it is quite a common case that many entirely different materials can be used to a given part. As a consequence material selection becomes quite a complex task

Materials selection is both critical and complex as……..:

Materials selection is both critical and complex as…….. ! Many new materials ! Many new material types ! New manufacturing methods ! Properties of existing materials improved ! Increased use of advanced materials ! Entirely new design configurations feasible ! Increased competition between materials

Properties Involved in Pre-Selection of Material Types :

Properties Involved in Pre-Selection of Material Types Lowest and highest use temperature - ageing - Physical and chemical degradation Environmental resistance - Corrosion resistance - UV-resistance - Toxicity Physical properties - Electrical and thermal conductivity - Density -Coefficient of thermal expansion Mechanical requirements Tensile strength -Elongation -Toughness

Key considerations are: :

Key considerations are: Thermal Properties Exposure to Chemicals Environmental Considerations Mechanical Properties such as….. • Tensile strength and Modulus • Impact strength • Compressive strength • Fatigue endurance • Creep • Stress-relaxation

Material Selection process :

Material Selection process The material selection should not be solely based on cost. A systematic approach to material selection process is necessary in order to select the best material for any application. The proper material selection technique involves carefully defining the application requirement in terms of mechanical, thermal, environmental, electrical and chemical properties. In many instances, it makes sense to design a thinner wall part taking advantage of the stiffness-to-weight ratio offered by higher-priced, fast cycling engineering materials . Many companies including material suppliers have developed software to assist in material selection simply by selecting application requirement in the order of importance. Material selection process starts with carefully defining the requirements and narrowing down the choices by the process of elimination. Designer must identify application requirements including mechanical, thermal, environmental and chemical. All special needs such as outdoor UV exposure, light transmission, fatigue, creep, stress relaxation, and regulatory requirements must be considered. Processing techniques and assembly methods play a key role in selecting appropriate material and should be given consideration.

Material Selection process :

Material Selection process Many plastics materials are susceptible to chemical attack and therefore behavior of plastics material in chemical environment is one of the most important considerations in selecting material. No single property defines material’s ability to perform in a given chemical environment and factors such as external or molded-in stresses, length of exposure, temperature, chemical concentration etc. should be carefully scrutinized. Some of the common pitfalls in material selection process are relying on published material property data, misinterpretation of data sheets and blindly accepting material supplier’s recommendations. Material property data sheets should only be used for screening various types and grades of materials and not for ultimate selection or engineering design. As discussed earlier, the reported data is generally derived from short term tests and single point measurements under laboratory condition using standard test bars. The published values are generally higher and do not correlate well with actual use conditions. Such data does not take into account the effect of time, temperature, environment and chemicals.

Figure shows a typical failure arising from improper material selection. :

Figure shows a typical failure arising from improper material selection.

APPLICATIONS:

APPLICATIONS Si3N4 ceramic bearing parts

APPLICATIONS:

APPLICATIONS Textile Reinforced Materials - materials in the form of ceramic or concrete are reinforced with a primarily woven or non-woven textile structure to impose high strength with comparatively more flexibility to withstand vibrations and sudden jerks . A cloth of woven carbon fiber filaments is commonly used for reinforcement in composite materials .

APPLICATIONS:

APPLICATIONS Household items made of various kinds of plastic. Polymer properties, synthesis, and characterization, for a specialized understanding of how polymers behave, how they are made, and how they are characterized; exciting applications of polymers include liquid crystal displays (LCDs, the displays found in most cell-phones, cameras, and iPods), novel photovoltaic devices based on semiconductor polymers (which, unlike the traditional silicon solar panels, are flexible and cheap to manufacture, albeit with lower efficiency), and membranes for room-temperature fuel cells (as proton exchange membranes) and filtration systems in the environmental and biomedical fields

PowerPoint Presentation:

The most advanced passenger aircraft ever Boeing 787”Dreamliner”quiter , enviormental and passenger friendly, achieved through ground breaking abilities of carbon fibers. The entire wing structure of A350 is made up of carbon fiber

comparison:

comparison  Material Tensile Strength ( GPa ) Tensile..Modulus ( GPa ) Density (g/ccm) Specific Strength (GPa) Standard Grade Carbon Fiber 3.5 230.0 1.75 2.00 High Tensile Steel 1.3 210.0 7.87 0.17

Future prospects:

Future prospects The superior properties of carbon fiber to steel and other metals meant that the aerospace industry was an obvious market for composite materials, the use of lighter materials in aircraft construction allows for fuel savings or a greater payload, Carbon fibers are used extensively in both military and civil aircraft structures. As the technology of producing composites advanced, other fibers were developed to supply this market .

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