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Published byHubert Briggs Modified over 8 years ago
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CERAMIC GROUP MEMBER MOHAMMAD AZALI BIN AZAHAR1120230 ZUL AFIQ ZAIM BIN ZULKEPLE1120232 AMALI ZULFADHLI BIN ANUAR1121140 MUHAMMAD HAZIQ BIN SALEHHUDDIN1121146
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DEFINATION A ceramic is an inorganic, nonmetallic solid prepared by the action of heat and subsequent cooling.Ceramic materials may have a crystalline or partly crystalline structure, or may be amorphous (e.g., a glass). Because most common ceramics are crystalline, the definition of ceramic is often restricted to inorganic crystalline materials, as opposed to the noncrystalline glasses, a distinction followed here.
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TYPE OF CERAMIC
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Alumina Also called corundum or emery Most widely used Used in pure form or as raw material High hardness and moderate strength Alumina + other oxides are used as refractory materials for high-temp applications Suitable as electrical and thermal insulation, cutting tools/abrasives, etc.
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Carbides Made of tungsten and titanium,silicon Examples : Tungsten carbide (WC), titanum carbide (TiC), silicon carbide (SiC)
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Diamond Diamond-Like Carbon (DLC) developed as diamond film coating Can be coated with Ni, Cu, or Ti for improved performance Cutting tools materials (single or polycrystalline) Abrasive in grinding Dressing of grinding wheels (abrasive sharpening) Dies for wire drawing Cutting tools and dies coating
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Nitrides Cubic boron nitride (CBN) Titanum nitride (TiN) Silicon nitride (Si3N4)
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Glass Amorphous solid Super-cooled liquid (cooled at a rate too high for crystal formation) Content more than 50% silica (glass former) Types of commercial glasses ¨ sodalime glass (most common), lead alkali glass, borosilicate glass, aluminosilicate glass, 96% silica glass, fused silica glass Thermal classification - hard (greater heat, e.g., borosilicate) or soft glass (e.g., soda lime glass ¨ lampworking)
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Glass ceramics High crystalline microstructure Stronger than glass Shaped and then heat treated Treatment process known as devitrification(recrystallization of glass) Near zero coefficient of thermal expansion, high thermal shock resistance
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Graphite Crystalline form of carbon layered structure Basal planes or sheets of close packed C atoms Weak when sheared along the layers Also known as lampblack (pigment High electrical and thermal conductivity Good resistance to thermal shock and high temperature
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Types of graphite Fibers - important use in reinforced plastics and composite materials Foams - high service temperature, chemical inertness, low coefficient of thermal expansion and electrical properties Carbon foams - graphitic or non-graphitic structures Buckyballs - carbon molecules in the shape of soccer balls. Also called fullerents, chemicallyinert, and act like solid lubricant particles
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Structural Properties
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Rock salt structure(AX)(NaCl )
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Spinel structure(AB2X4)(MgAl2O4)
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Crystal Structures Ceramic bonds are mixed, ionic and covalent, with a proportion that depends on the particular ceramics. The ionic character is given by the difference of electronegativity between the cations (+) and anions (-). Covalent bonds involve sharing of valence electrons. Very ionic crystals usually involve cations which are alkalis or alkaline-earths (first two columns of the periodic table) and oxygen or halogens as anions.
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The building criteria for the crystal structure are two: maintain neutrality charge balance dictates chemical formula achieve closest packing the condition for minimum energy implies maximum attraction and minimum repulsion. This leads to contact, configurations where anions have the highest number of cation neighbors and viceversa.
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COMPLEX SILICATE STRUCTURES The majority of ceramic materials, in particular those derived from clay, sand, or cement, contain the element silicon in the from of silicates.
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Mechanical properties
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Application Automotive: Brake pads Ceramic materials retain their properties at elevated temperatures due to the strong ionic-covalent bonding. Safety glass windshield Ceramic materials retain their properties at high pressure due to the strong ionic-covalent bonding.
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Medical (Bioceramics): Dental restoration Ceramics materials has low reactivity towards acids and enzymes in the mouth due to its covalent bonding. Bone implants Ceramics materials has low reactivity towards the fluid and chemical substance in human body due to its covalent bonding.
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