The band theory of solids 8. Semiconductors 9. Principles of semiconductor devices Dielectric materials Magnetic materials Lasers Optoelectronics Superconductivity In he settled in England where he worked first in industry and later at the University of Oxford. He did research on antennas, microwaves, superconductors, holographic gratings, photorefractive materials, and metamaterials.
He published 8 books and over papers. He has been a Fellow of the Royal Society since He came to the Department of Engineering Science, Oxford in as a research fellow to help the newly appointed Reader in Electrical Engineering start a research group in microwave electronics, and later became a lecturer and college fellow.
Richard R. He has published around journal papers, conference papers and 2 books on holography, guided wave optics, electromagnetic theory, metamaterials, magnetic resonance imaging, and micro-electro-mechanical systems MEMS , and has 18 granted patents. In , he co-founded the Imperial College spin-out company Microsaic Systems. Oxford University Press is a department of the University of Oxford. Advertisement Hide.
This service is more advanced with JavaScript available. Electronic Properties of Materials. Authors view affiliations Rolf E. Widely used, course-tested text is now available in an updated Fourth Edition Introduces the elements of solid-state physics that are required to understand the coverage of electrical, optical, magnetic, and thermal properties of materials and their applications Stresses concepts rather than mathematical formalism Describes the materials basis of the next generation of electronic devices Designed for a single, week semester course Supplemental and more detailed information for graduate students is marked with an asterisk Divided into five independent modules to suit different course needs Presents many end-of-chapter problems with numerical solutions in an appendix Includes supplementary material: sn.
Front Matter Pages i-xix. Front Matter Pages Pages The Wave-Particle Duality. Energy Bands in Crystals. Electrons in a Crystal. Electrical Conduction in Metals and Alloys. The Optical Constants. Cast Iron: When we melt the pig iron in the presence of coke and calcium carbonate the product obtained is called cast iron.
It has gray white color its gray color is due to the presence of graphite and white due to the presence of carbon carbides. It can be transferred into different molds of desired shapes and size. Wrought Iron: It is the purest form of iron. It contains In wrought iron corrosion will be large. It is the most common type of iron used in engineering. Steel: Steels are the large family of metals which consists mostly of iron and other elements usually carbon ranging 0.
Steel goes harder and tougher with a n increase in carbon content up to 1. When a force is subjected to an engineering material it may result in translation, rotation and deformation of that material.
Aspects of translation and rotation of materials are deled by engineering dynamics. We restrict our cells here to the subject of materials under deformation forces. For example when using a rope to lift a load. For example a column that supports an overhead beam is in compression.
Shear force can separate the materials by sliding part of it in one direction and rest of part is in opposite direction. Shear stress in this case is the function of applied torque. Shear strain is related to the angle of twist. In short torsion is twisting any object due to an applied torque. Permanent deformation is irreversible and stays even after the removal of applied forces such a deformation is called as plastic deformation while the temporary deformation is reversible and disappears after the removal of applied forces such a deformation is called as elastic deformation.
So elastic deformation is recoverable. Both kinds of deformation can be a function of time or independent of time. Inelastic Deformation: Time dependent recoverable deformation under load is called as inelastic deformation. Creep: Time dependent progressive permanent deformation under constant load is called creep. Stress: When a material is subjected to an external force it will either totally comply with that force and be pushed away or it will set up the internal forces to oppose that forces.
Solid materials are generally act wither like a spring when stressed or compressed the internal forces come into play as it is easily seen when spring is released. A material is subjected to an external force that tends to stretch it is called as tension.
Whereas forces which squeeze the material are put in compression. Since strain is the ratio of two lengths so it has no units and it frequently expressed as percentage. If a spring is gradually stretched the force needed to increase but the material spring that to its original shape when the force is increased.
This linear relationship between stress and strain can be shown in the form of a graph as this graph shows that as we increase or decrease the stress the strain also increase or decrease with same proportion respectively. So both are directly proportional to each other. The point at which the straight line behavior ceases is called limit of proportionality.
Beyond this the material will not spring back to its original shape and said to exhibit some plastic behavior. This stress at which the material starts to exhibits permanent deformation is called elastic limit or yield point.
If stress is increased beyond yield point the sample will eventually break. The slope of stress over strain graph varies with stress so we gradually take the slope of initial straight line portion.
It is the one of the important property of metals. When metals are heated they expand and become larger while cooling the metals causes them to contract or shrink in size. It is very important for metals that are used in process industry to consider temperature changes and how they affect the metals. Metal density is very important factor in different structures i.
We measure the amount of penetration and then compare it with the standard scale for ferrous metals which are usually harder than the non ferrous metals a diamond strip is used which is indicated by a Rockwell number represented by C. Toughness of metal should be able to absorb energy up to fracture. It enables materials with stand shocks and to be deformed without rupturing when a rod is bend its outer surface is stretches and the inside radius of the rod is compresses the more a material is bends the more outer surface is stretches an inner radius is contracts a tough material is one that gives relatively small changes in length when subjected to tension and compression in the other words the small value of stress over strain.
Tough materials are desirables to vehicles, machines and large structures. Elasticity is the ability of the materials to return in to its original shape after the load is removed theoretically the elastic limit of a material is the limit to which material is loaded and still recovers its original shape after the load is removed.
Ductile metals are vitals in creating wires or tubes because of its easy of forming. While cast iron and cast aluminum very hard steel and glass is the one of the best example of the brittle materials. Generally a brittle metal are very high in the compression strength and in tensile strength. Brittle metals are not suitable for the heavy loads as they could break easily and can cause the damage.
Here metals are liquefied and then joined together when it becomes harden it becomes one piece. Steel liquefy at oF while aluminum alloy at oF. It occurs as the result of the long term exposure to a high level of stress that are below the yield point of the material. Creep is more swear in materials that are subjected to heat for the long periods and near the melting points. Creep deformation is the time dependent deformation.
The temperature ranges in which the creep deformation may occur is different in various metals. Some important non ferrous metals are aluminum, copper, lead, tin and zinc. Aluminum: Aluminum found its maximum use in every field of engineering due to its particular properties softness, lightweight it has become very useful metal in all over the world. Modified metallurgical processes have improved strength and durability of different metals to such an extent that it has made maximum use of aluminum in engineering processes.
Copper: Copper is one of the most widely used metal but due to its high price we use it with some limitations in engineering work. Tin: Tin is very common metal in the family of non ferrous metals. It is mostly use as a protection layer for the protection of different metals.
For examples Sr. Name Composition no. The nickel increases the strength and the elastic limit of the alloys usually nickel steel contains 0. It is sometimes called high speed steel. Chromium has high affinity for oxygen and forms stable oxides films on the surface of the stainless steel the film is called the passive oxide layer and form instantaneously in ordinary atmosphere this films is self healing and rebuilds when it has been removed this film that gives the stainless steel corrosion resistance in metallurgy stainless steel is also called inox steel or simply inox.
The most widely useful austenitic steel is grade or A2 SS. Increases the chromium a parts increases the resistance to corrosion at elevated temperatures. Ferritic steel have better engineering properties then austenitic steel.
Series includes many Ferritic steels. These steels are not corrosion resistance as austenitic steel and Ferritic steels but are extremely strong and tough.
The high carbon content of this steel allows them to response well to the heat treatment to gives various mechanical strength such as hardness. They have mixed microstructure of the both austenitic stainless steel and Ferritic stainless steel. Lean duplex stainless steel is formulated to have comparable corrosion resistance to the standard austenitic stainless steel but enhanced strength and resistance to stress corrosion cracking.
0コメント