The Importance of Engineering Materials in Present World PDF

International Journal of Science and Research (IJSR) ISSN (Online): 2319-7064 Index Copernicus Value (2015): 78.96 | Impact Factor (2015): 6.391 The Importance of Engineering Materials in Present W...

International Journal of Science and Research (IJSR) ISSN (Online): 2319-7064 Index Copernicus Value (2015): 78.96 | Impact Factor (2015): 6.391 The Importance of Engineering Materials in Present World Satya Prakash Pandey1, Vishwajeet Singh2 1 Mechanical Engineering Department, Rajarshi Rananjay Sinh Institute of Management and Technology, Amethi (U.P), 227405, India 2 Student of Mechanical Engineering, Rajarshi Rananjay Sinh Institute of Management and Technology, Amethi (U.P), 227405, India Abstract: Materials had been in use of humanity since time immemorial. Our world is all about materials that are why Materials Science and Engineering has taken centre-stage position in many developed and developing nations. There have been changes in man’s choice of materials for his engineering activities. Materials went through ages of man’s activities on earth like the Stone Age, the Iron Age and the current Silicon age, etc. But the challenges of current worlds needs are constantly fuelling the need discovery and development of new kinds of materials with the desired properties and the relevant cost to meet the challenges of the world. This informative article is, therefore, aimed at reviewing the advances made in engineering materials, their classification and the importance of engineering materials in current day world, their properties and various areas of application. Keywords: Material, Advancement, Engineering, Importance 1. Introduction From a functional perspective, the role of a materials scientist is to develop or synthesize new materials, whereas a Materials are probably more significant in our culture than materials engineer is called upon to create new products or we realize. Transportation, housing, clothing systems using existing materials and/or to develop communication, reaction and food production and virtually techniques for processing materials. every segment of our daily lives is influenced by materials. Materials have contributed to the advancement of a number 2.1 Elements of Materials Science and Engineering of technologies, including medicine & health, information & communication, national security & space, transportation, There are four essential elements in materials science and structural materials, arts & literature, textiles, personal engineering hygiene, agriculture & food science & the environment. 1) Processing/synthesis These inter-disciplinary interactions between the Material 2) Structure/composition sciences and other fields in the development of new 3) Properties materials and their applications is to be understood well. 4) Performance/application As the contribution of materials science and engineering to These four elements of Materials Science and Engineering is other disciplines increases, it will become necessary for primarily concerned with the study of the basic knowledge scientists of all backgrounds to better understand it. of materials: the relationships between the Although it is not feasible for scientists to master a vast composition/structure, properties and processing of body of scientific knowledge over many disciplines, materials. Materials engineering is mainly concerned with scientists must gain the skills that will allow them to master the use of this fundamental knowledge to design and to some specific topics. Our presentation attempts to present a produce materials with properties that will meet the relatively brief overview of Materials Science and Materials requirements of society. As subjects of study, materials Engineering and their importance in the present day world. It science and materials engineering are very often closely will also attempt to examine the four components that make related. The subject ―materials science and engineering" up the whole gamut of the discipline of materials science combines both a basic knowledge and application and forms and engineering and their inter-relationship. a bridge between the basic sciences (physics, chemistry and mathematics) and the various engineering disciplines, 2. Materials Science and Engineering including electrical, mechanical, chemical, and civil and aerospace engineering. Materials Science and Engineering – (a) materials science, (b) materials engineering The structure of a material usually relates to the arrangement of its internal components. Subatomic structure involves Materials science involves investigating the relationships electrons within the individual atoms and interactions with that exist between the structures and properties of materials their nuclei. On an atomic level, structure encompasses the organization of atoms or molecules relative to one another. Materials engineering is based on the application of this The next larger structural realm, which contains large groups structure-property correlations, in designing or engineering of atoms that are normally agglomerated together, is termed the structure of a material to produce a pre-determined set of ―microscopic, meaning that which is subject to direct properties observation using some type of microscope. Finally, Volume 6 Issue 3, March 2017 www.ijsr.net Licensed Under Creative Commons Attribution CC BY Paper ID: ART20171428 433  International Journal of Science and Research (IJSR) ISSN (Online): 2319-7064 Index Copernicus Value (2015): 78.96 | Impact Factor (2015): 6.391 structural elements that may be viewed with the naked eye Virtually all important properties of solid materials may be are termed ―macroscopic. grouped into six different categories: Material structure can be classified as: macrostructure, microstructure, substructure, crystal structure, electronic 1) Mechanical properties relate deformation to an applied structure and nuclear structure. load or force; examples include: elastic modulus or Young's modulus and strength; tensile and shear (a) Macro structure - The macrostructure of a material is strengths, hardness, toughness, ductility, deformation and examined by low-power magnification or naked eye. It fracture behaviours, fatigue and creep strengths, wear deals with the shape, size and atomic arrangement in a resistance, etc. The important mechanical properties crystalline material. In case of some crystals, e.g., quartz, affecting the selection of a material are: external form of the crystal may reflect the internal a) Tensile Strength: This enables the material to resist the symmetry of atoms. Macrostructure may be observed application of a tensile force. To withstand the tensile directly on a fracture surface or on a forging specimen. force, the internal structure of the material provides the The individual crystals of a crystalline material can be internal resistance. visible, e.g. in a brass doorknob by the constant polishing b) Hardness: It is the degree of resistance to indentation or and etching action of a human hand and sweat. scratching, abrasion and wear. Alloying techniques and Macrostructure can reveal flaws, segregations; cracks etc. heat treatment help to achieve the same. by using proper techniques and one can save much c) Ductility: This is the property of a metal by virtue of expenses by rejecting defective materials at an early which it can be drawn into wires or elongated before stage. rupture takes place. It depends upon the grain size of the (b) Micro structure - This generally refers to the structure metal crystals. of the material observed under optical microscope. d) Impact Strength: It is the energy required per unit cross- Optical microscopes can magnify a structure about 1500 sectional area to fracture a specimen, i.e., it is a measure to 3000 times linear, without loss of resolution of details of the response of a material to shock loading. of the material structure. We may note that optical e) Wear Resistance: The ability of a material to resist microscopes can resolve two lines separately when their friction wear under particular conditions, i.e. to maintain difference of separation is 10–7 m (= 0.1 _m). Cracks, its physical dimensions when in sliding or rolling contact porosity, non-metallic inclusions within materials can be with a second member. revealed by examining them under powerful optical f) Corrosion Resistance: Those metals and alloys which microscope. can withstand the corrosive action of a medium, i.e. (c) Sub structure - When crystal imperfections such as corrosion processes proceed in them at a relatively low dislocation in a structure are to be examined, a special rate are termed corrosion-resistant. microscope having higher magnification and resolution g) Density: This is an important factor of a material where than the optical microscope is used. Electron microscope weight and thus, the mass is critical, i.e. aircraft with magnifications 105 are used for this purpose. components. Another important modern microscope is field ion microscope, which can produce images of individual 2) Thermal properties of solids can be represented in atoms as well as defects in atomic arrangements. terms of heat capacity and thermal conductivity; the (d) Crystal structure - This reveals the atomic arrangement characteristics of a material, which are functions of the within a crystal. X-ray diffraction techniques and temperature, are termed its thermal properties. One can electron diffraction method are commonly used for predict the performance of machine components during studying crystal structure. It is usually sufficient to study normal operation, if he has the knowledge of thermal the arrangement of atoms within a unit cell. The crystal is properties. Specific heat, latent heat, thermal formed by a very large number of unit cells forming conductivity, thermal expansion, thermal stresses, regularly repeating patterns in space. thermal fatigue, etc., are few important thermal (e) Electronic structure - This refers to the electrons in the properties of materials. These properties play a vital role outermost shells of individual atoms that form the solid. in selection of material for engineering applications, e.g. Spectroscopic techniques are commonly used for when materials are considered for high temperature determining the electronic structure. service. Now, we briefly discuss few of these properties: (f) Nuclear structure - This is studied by nuclear a) Specific Heat: It is the heat capacity of a unit mass of spectroscopic techniques, e.g., nuclear magnetic a homogeneous substance. For a homogeneous body, resonance (NMR) c = C/M, where C is the heat capacity and M is the mass of the body. One can also define it as the 2.2 Properties of Materials quantity of heat required to raise the temperature of a unit mass of the substance through 1°C. Its units are A property is a material trait in terms of the kind and cal/g/°C. magnitude of response to a specific imposed stimulus. b) Thermal Conductivity (K): This represents the Generally, definitions of properties are made independent of material shape and size. The properties of engineering amount of heat conducted per unit time through a unit materials can be classified into two main groups area perpendicular to the direction of heat conduction (a) physical when the temperature gradient across the heat (b) Chemical. conducting element is one unit. Truly speaking the capability of the material to transmit heat through it is Volume 6 Issue 3, March 2017 www.ijsr.net Licensed Under Creative Commons Attribution CC BY Paper ID: ART20171428 434  International Journal of Science and Research (IJSR) ISSN (Online): 2319-7064 Index Copernicus Value (2015): 78.96 | Impact Factor (2015): 6.391 termed as the thermal conductivity. The higher the to their excellent magnetic properties alongwith their high value of thermal conductivity, the greater is the rate at electrical resistivity these materials today, find use in a which heat will be transferred through a piece of variety of applications like magnetic recording tapes, given size. Copper and aluminum are good inductors and transformers, memory elements, microwave conductors of heat and therefore, extensively used devices, bubble domain devices, recording hard cores, etc. whenever transfer of heat is desired. Bakelite is a Hysteresis, permeability and coercive forces are some of the magnetic properties of magnetic substances which are to be poor conductor of heat and hence used as heat considered for the manufacture of transformers and other insulator. The heat flow through an area A which is electronic components. perpendicular to the direction of flow is directly proportional to the area (A) and thermal gradient 4) Electrical Properties- Electrical conductivity, (dt/dx). resistivity, dielectric strength, the stimulus is an electric c) Thermal Expansion: All solids expand on heating field are few important electrical properties of a material. and contract on cooling. Thermal expansion may take A material which offers little resistance to the passage of place as linear, circumferential or cubical. A solid an electric current is said to be a good conductor of which expands equally in three mutually orthogonal electricity. The electrical resistance of a material depends directions is termed as thermally isotropic. The on its dimensions and is given by: Usually resistivity of a increase in any linear dimension of a solid, e.g. material is quoted in the literature. Unit of resistivity is length, width, height on heating is termed as linear Ohm-metre. On the basis of electrical resistivity expansion. The coefficient of linear expansion is the materials are divided as: a) Conductors increase in length per unit length per degree rise in b) Semiconductors temperature. The increase in volume of a solid on c) Insulators. heating is called cubical expansion. The thermal In general metals are good conductors. Insulators have very expansion of solids has its origin in the lattice high resistivity. Ceramic insulators are most common vibration and lattice vibrations increases with the rise examples and are used on automobile spark plugs, Bakelite in temperature. Obviously, the thermal conductivity handles for electric iron, plastic coverings on cables in (K) and electrical conductivity (σ) vary in the same domestic wiring. fashion from one material to another. d) Thermal Resistance (RT): It is the resistance offered 5) Optical properties - The optical properties of materials, by the conductor when heat flow due to temperature e.g. refractive index, reflectivity and absorption difference between two points of a conductor. It is coefficient etc. affect the light reflection and transmission given by: where H _ rate of heat flow and ᶿ1 and ᶿ2 the stimulus is electromagnetic or light radiation. are temperatures at two points (°C). e) Thermal Diffusivity (h): It is given by: A material 6) Chemical Properties -These properties includes atomic having high heat requirement per unit volume weight, molecular weight, atomic number, valency, chemical composition, acidity, alkalinity, etc. These possesses a low thermal diffusivity because, more properties govern the selection of materials particularly heat must be added to or removed from the material in Chemical plant. Deteriorative characteristics relate to for effecting a temperature change. the chemical reactivity of materials. In addition to f) Thermal Fatigue: This is the mechanical effect of structure and properties, two other important components repeated thermal stresses caused by repeated heating are involved in the science and engineering of and cooling. The thermal stresses can be very large, materials— namely, ―processing‖ ―performance.With involving considerable plastic flow. We can see that regard to the relationships of these four components, the fatigue failures can occur after relatively few cycles. structure of a material will depend on how it is The effect of the high part of the temperature cycle on processed. Furthermore, a material‗s performance will be the strength of material plays an important factor in a function of its properties. reducing its life under thermal fatigue. 3. Classification of Materials in Engineering 3) Magnetic properties demonstrate the response of a material to the application of a magnetic field. Materials The traditional method is to classify them according to their in which a state of magnetism can be induced are termed nature into metals, ceramics, polymers and composites. The magnetic materials. There are five classes into which factors which form the basis of various systems of magnetic materials may be grouped: classifications of materials in material science and (i) diamagnetic engineering are: (ii) paramagnetic 1. The chemical composition of the material, (iii) ferromagnetic 2. The mode of the occurrence of the material in the nature, (iv) antiferromagnetic 3. The refining and the manufacturing process to which the material is subjected to prior to acquiring the required (v) ferrimagnetic. properties, Iron, Cobalt, Nickel and some of their alloys and compounds 4. The atomic and crystalline structure of material and possess spontaneous magnetisation. Magnetic oxides like 5. The industrial and technical use of the material. ferrites and garnets could be used at high frequencies. Due Volume 6 Issue 3, March 2017 www.ijsr.net Licensed Under Creative Commons Attribution CC BY Paper ID: ART20171428 435