Ceramics

Ceramics

اسلاید 1: Ceramics

اسلاید 2: CeramicsA wide-ranging group of materials whose ingredients are clays, sand and felspar.

اسلاید 3: ClaysContain some of the following:Silicon & Aluminium as silicatesPotassium compoundsMagnesium compoundsCalcium compounds Sand contains Silica and Feldspar or Aluminium Potassium Silicate.

اسلاید 4: Types of CeramicsWhitewaresRefractoriesGlassesAbrasivesCements

اسلاید 5: Comparison metals v ceramicsCeramicsMetals

اسلاید 6: Bonded Clay Ceramics Made from natural clays and mixtures of clays and added crystalline ceramics. These include:Whitewares Structural Clay Products Refractory Ceramics

اسلاید 7: Whitewares CrockeryFloor and wall tilesSanitary-wareElectrical porcelainDecorative ceramics

اسلاید 8: Whiteware: Bathrooms

اسلاید 9: Slip CastingSinter and Serve

اسلاید 10: Whitewares

اسلاید 11: Refractories Firebricks for furnaces and ovens. Have high Silicon or Aluminium oxide content.Brick products are used in the manufacturing plant for iron and steel, non-ferrous metals, glass, cements, ceramics, energy conversion, petroleum, and chemical industries.

اسلاید 12: RefractoriesUsed to provide thermal protection of other materials in very high temperature applications, such as steel making (Tm=1500°C), metal foundry operations, etc. They are usually composed of alumina (Tm=2050°C) and silica along with other oxides: MgO (Tm=2850°C), Fe2O3, TiO2, etc., and have intrinsic porosity typically greater than 10% by volume. Specialized refractories, (those already mentioned) and BeO, ZrO2, mullite, SiC, and graphite with low porosity are also used.

اسلاید 13: Refractory Brick

اسلاید 14: Amorphous Ceramics (Glasses)Main ingredient is Silica (SiO2) If cooled very slowly will form crystalline structure. If cooled more quickly will form amorphous structure consisting of disordered and linked chains of Silicon and Oxygen atoms. This accounts for its transparency as it is the crystal boundaries that scatter the light, causing reflection. Glass can be tempered to increase its toughness and resistance to cracking.

اسلاید 15: Glass TypesThree common types of glass:Soda-lime glass - 95% of all glass, windows containers etc.Lead glass - contains lead oxide to improve refractive indexBorosilicate - contains Boron oxide, known as Pyrex.

اسلاید 16: Glasses Flat glass (windows)Container glass (bottles)Pressed and blown glass (dinnerware)Glass fibres (home insulation)Advanced/specialty glass (optical fibres)

اسلاید 17: Glass Containers

اسلاید 18: Pressed Glass ProcessingSoftenedGob

اسلاید 19: Blow MoldingSoftened glass

اسلاید 20: Glass in Buildings

اسلاید 21: Plate Glass Drawing Processes

اسلاید 22: Tempered GlassThe strength of glass can be enhanced by inducing compressive residual stresses at the surface. The surface stays in compression - closing small scratches and cracks.Small Scratches

اسلاید 23: Hardening ProcessesTempering:Glass heated above Tg but below the softening pointCooled to room temp in air or oilSurface cools to below Tg before interiorwhen interior cools and contracts it draws the exterior into compression. Chemical Hardening:Cations with large ionic radius are diffused into the surfaceThis strains the “lattice” inducing compressive strains and stresses.

اسلاید 24: Armoured GlassMany have tried to gain access with golf clubs and baseball bats but obviously the glass remains intact ! From time to time a local TV station intends to show videos of those trying to get at the cash!!

اسلاید 25: Leaded Glass

اسلاید 26: Crystalline CeramicsGood electrical insulators and refractories.Magnesium Oxide is used as insulation material in heating elements and cables.Aluminium OxideBeryllium OxidesBoron CarbideTungsten Carbide. Used as abrasives and cutting tool tips.

اسلاید 27: AbrasivesNatural (garnet, diamond, etc.)Synthetic abrasives (silicon carbide, diamond, fused alumina, etc.) are used for grinding, cutting, polishing, lapping, or pressure blasting of materials

اسلاید 28: CementsUsed to produce concrete roads, bridges, buildings, dams.

اسلاید 29: Advanced CeramicsAdvanced ceramic materials have been developed over the past half century Applied as thermal barrier coatings to protect metal structures, wearing surfaces, or as integral components by themselves. Engine applications are very common for this class of material which includes silicon nitride (Si3N4), silicon carbide (SiC), Zirconia (ZrO2) and Alumina (Al2O3) Heat resistance and other desirable properties have lead to the development of methods to toughen the material by reinforcement with fibers and whiskers opening up more applications for ceramics

اسلاید 30: Advanced CeramicsStructural: Wear parts, bioceramics, cutting tools, engine components, armour.Electrical: Capacitors, insulators, integrated circuit packages, piezoelectrics, magnets and superconductorsCoatings: Engine components, cutting tools, and industrial wear partsChemical and environmental: Filters, membranes, catalysts, and catalyst supports

اسلاید 31: Engine ComponentsRotor (Alumina)Gears (Alumina)

اسلاید 32: Turbocharger Ceramic Rotor

اسلاید 33: Ceramic Brake Discs

اسلاید 34: McLaren Mercedes Benz

اسلاید 35: Silicon CarbideAutomotive Components in Silicon CarbideChosen for its heat and wear resistance

اسلاید 36: Ceramic ArmourCeramic armour systems are used to protect military personnel and equipment. Advantage: low density of the material can lead to weight-efficient armour systems. Typical ceramic materials used in armour systems include alumina, boron carbide, silicon carbide, and titanium diboride. The ceramic material is discontinuous and is sandwiched between a more ductile outer and inner skin. The outer skin must be hard enough to shatter the projectile.

اسلاید 37: Most of the impact energy is absorbed by the fracturing of the ceramic and any remaining kinetic energy is absorbed by the inner skin, that also serves to contain the fragments of the ceramic and the projectile preventing severe impact with the personnel/equipment being protected. Alumina ceramic/Kevlar composite system in sheets about 20mm thick are used to protect key areas of Hercules aircraft (cockpit crew/instruments and loadmaster station). This lightweight solution provided an efficient and removable/replaceable armour system. Similar systems used on Armoured Personnel Carrier’s.

اسلاید 38: Ceramic - Composite Armor

اسلاید 39: Silicon CarbideBody armour and other components chosen for their ballistic properties.