524 SILICON CARBIDE Vol. 22 SILICON CARBIDE 1. Introduction Silicon carbide [409-21-2] (SiC) is a technologically important material that is one of the small number of unusual materials that were first created synthetically and then subsequently discovered in nature. Silicon carbide was first observed in its natural form in 1905 by the Nobel-prize-winning chemist Henri Moissan‚ who discovered it in the meteor that created the Diablo Canyon in Arizona. The transparent mineral‚ now known as
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alloying elements in stainless steel include chromium‚ nickel‚ and molybdenum. Characteristic of alloying elements Very important elements for alloy steels are manganese‚ nickel‚ chromium‚ molybdenum‚ vanadium‚ tungsten‚ silicon‚ copper‚ cobalt and boron. All commercial steels contain 0‚3-0‚8% manganese‚ to reduce oxides and to counteract the harmful influence of iron sulphide. There is a tendency nowadays to increase the manganese content and reduce the carbon content in order to get a steel with
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the title of the box for that family. Hydrogen Family – 1 Alkali metals – 3‚ 11‚ 19‚ 37‚ 55‚ 87 Alkaline earth metals – 4‚ 12‚ 20‚ 38‚ 56‚ 88 Transition metals – d block and 13‚ 31‚ 32‚ 49‚ 50‚ 51‚ 81‚ 82‚ 83‚ 84 Rare earth metals – f block Boron Family – 5 Carbon Family – 6‚ 14 Nitrogen Family – 7‚ 15‚ 33 Oxygen Family (Chalcogens) – 8‚ 16‚ 34‚ 52 Halogens – 9‚ 17‚ 35‚ 53‚ 85 Noble gases – 2‚ 10‚ 18‚ 36‚ 54‚ 86 Use the internet to complete the following tasks Draw the ‘metal vs non-metal
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IONIC COMPOUNDS In chemistry‚ an ionic compound is a chemical compound in which ions are held together in a lattice structure by ionic bonds. Usually‚ the positively charged portion consists of metal cations and the negatively charged portion is an anion or polyatomic ion. Ions in ionic compounds are held together by the electrostatic forcesbetween oppositely charged bodies. Ionic compounds have high melting and boiling points‚ and they are hard and very brittle. Ions can be single atoms‚ as the sodium and chlorine in
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agricultural machinery. Examples of ceramics used are alumina and zirconia * Ceramics have high hardness and toughness values making them useful in the manufacture of cutting tools and shielding armor. examples of materials used are alumina and boron carbide Advanced Ceramics find application in specific areas such as: * NANOMATERIALS Ceramics find application in nano-materials as ceramic nano-composites i.e. second phase particles‚ fibers and whiskers are incorporated into the ceramic
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words. model answer: A gas-cooled nuclear reactor consists of the reactor itself and a heat exchanger. The reactor contains uranium fuel elements which are surrounded by graphite moderators and topped by charge tubes for loading fuel elements‚ and boron control rods. The whole reactor is contained in a pressure
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Apache AH-64A‚ this aircraft is used in the battlefield‚ so taking hits is unavoidable‚ this basic structure allows the AH-64A to receive hits and still be able to operate. The crew and vital components are protected by armour composed of bonded boron carbide and Kevlar. When shot at‚ the Kevlar backing gives and expands to absorb the remaining energy and prevents the shrapnel from entering the aircraft. Other uses of Kevlar: Body armour (bulletproof vests‚
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He had a good experience in managing start-up companies and developing their business plans. Agro limited deals with the special type of chemical compound named Borono-198 which is was a new fungicide in the market. Borono-198 was combination of boron and chloro group effective for biological activities.Borono-198 had tremendous results against harmful fungus in cash crops‚ oak trees and fluid tanks. It was available at low prices from all other fungicides from competing companies. 10‚000 gallons
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SUBMISSION INSTRUCTIONS: WHAT: Printed questionnaire with the answers written in a big yellow booklet. One page per number. Paginate each page accordingly. Use different inks to distinguish the bonds of electrons for numbers involving molecular structure. WHO: All students with Student Number ending in ODD number will answer Set A while students with Student Number ending in EVEN number will answer Set B. Indicate your Student Number and the Set you are answering in front of the yellow
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Chemistry 1. Explain why 0-nitrophenol has a lower boiling point than p-nitrophenol? 2. Why alkali metals used in photoelectric cells? 3. Due to which compound‚ ozone depletion is caused in Antarctica? 4. Which of the element among B‚ Al‚ C and Si :- a. Has the highest first ionization enthalpy? b. Has the most negative electron gain enthalpy? 5. c. Write the atomic number of the element present in the third period and seventeenth group of the periodic table
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