CERAMIC GROUP MEMBER  MOHAMMAD AZALI BIN AZAHAR  ZUL AFIQ ZAIM BIN ZULKEPLE  AMALI ZULFADHLI BIN ANUAR  MUHAMMAD HAZIQ BIN SALEHHUDDIN

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.

TYPE OF CERAMIC

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.

Carbides  Made of tungsten and titanium,silicon  Examples : Tungsten carbide (WC), titanum carbide (TiC), silicon carbide (SiC)

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

Nitrides  Cubic boron nitride (CBN)  Titanum nitride (TiN)  Silicon nitride (Si3N4)

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)

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

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

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

Structural Properties

Rock salt structure(AX)(NaCl )

Spinel structure(AB2X4)(MgAl2O4)

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.

 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.

 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.

Mechanical properties 

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.

 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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