Ceramics

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31 0 Ceramics 

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Ceramics A wide-ranging group of materials whose ingredients are clays, sand and felspar. 

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Clays Contain some of the following: = Silicon & Aluminium as silicates ™ Potassium compounds ™ Magnesium compounds ™ Calcium compounds Sand contains Silica and Feldspar or Aluminium Potassium Silicate. 

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Types of Ceramics = Whitewares = Refractories balk ©] ‏تدا‎ = Abrasives كارع معن " 

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Comparison metals v ceramics Ceramics Crystal structure Crystal structure Large number of free electrons Captive electrons Metallic bond Tonic/covalent bonds Good electrical conductivity Poor conductivity (Opaque ‘Transparent (in thin sections) ‘Uniform atoms Different-size atoms High tensile strength Poor tensile strengtht Low shear strength High shear strength ‘Good ductility Poor ductility (brittle) Plastic flow None Impact strength Poor impact strength Relatively high weight Lower weight Moderate hardness Extreme hardness Nonporous Initial high porosity High density Initial low density 

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Bonded Clay Ceramics Made from natural clays and mixtures of clays and added crystalline ceramics. These include: bn Ada RN ol R= = Structural Clay Products ™ Refractory Ceramics 

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Whitewares ™ Crockery = Floor and wall tiles ‏ح زا-1‎ ® Electrical porcelain ™ Decorative ceramics 

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Whiteware: Bathrooms 

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Slip Casting assemble mould pour slip into mould drain residue 

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Whitewares 

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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. 

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Refractories © Osed to provide thercod! proteniioa oP vtker wateriats i ۱۱ RE A cies NaI La ea PR Ce oR AC RS (VT =(60O°C), wed Pourdyy 7 © Dhey oe wud) cowposed oP ohkevicrs (P_=COSO*O) wed silica ‏ل‎ (T,=COSO°C), ۱۹-۱ ‏اا‎ aha ard ‏ل ا ا‎ ‎١ 421 222 2 2‏ ‎aT ae ee acid‏ اا ا ا م زف اد مه سره 

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Refractory Brick 35 

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Amorphous Ceramics (Glasses) = Main ingredient is Silica (SiOz) = If cooled very slowly will form crystalline ‏۲۱و‎ go = 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 ‏کر فتزرت‎ ™ Glass can be tempered to increase its toughness and resistance to cracking. 

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Glass Types Three common types of glass: ™ Soda-lime glass - 95% of all glass, windows containers etc. ® Lead glass - contains lead oxide to improve refractive index " Borosilicate - contains Boron oxide, known as Pyrex. 

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نت6 = Flat glass (windows) ™ Container glass (bottles) ™ Pressed and blown glass (dinnerware) ™ Glass fibres (home insulation) ™ Advanced/specialty glass (optical fibres) 

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Glass Containers 

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Pressed Glass Processing iA gob drops feb settles and 1 ple into mould inger descends Ww final shay finished presse product 

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Blow Molding + Softened glass 

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Glass in Buildings 

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Plate Glass Drawing Processes 

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Tempered Glass وق ات The strength of glass can be enhanced by inducing compressive residual stresses at the ‏.ع2 ]الاك‎ ۲۳6 5۲۲۵6۵ 5۵۷5 0 compression - closing small scratches and : 6 ‏.اع‎ 120 80 40 0 40 80 120 Compression _Stress (MPa) Tension 

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Hardening Processes = Tempering: - Glass heated above T, but below the softening point - Cooled to room temp in air or oil - Surface cools to below T, before interior - when interior cools and contracts it draws the exterior into compression. = Chemical Hardening: - Cations with large ionic radius are diffused into the arctic} - This strains the “lattice” inducing compressive 5۲۲2185 200 6۰ 

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Armoured Glass ™ Many have tried 0 gain access with golf clubs and baseball bats but obviously intact ! From time to time a local TV station intends to show videos of those trying to get at the cash!! 

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Leaded Glass 

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Crystalline Ceramics Good electrical insulators and refractories. ™ Magnesium Oxide is used as insulation material in heating elements and cables. = Aluminium Oxide ™ Beryllium Oxides = Boron Carbide = Tungsten Carbide. ™ Used as abrasives and cutting tool tips. 

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Abrasives = Natural (garnet, diamond, etc.) = Synthetic abrasives (silicon carbide, diamond, fused alumina, etc.) are used for grinding, cutting, polishing, lapping, or pressure blasting of materials 

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Cements ™ Used to produce concrete roads, bridges, buildings, dams. 

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Advanced Ceramics SRO ‏ا ا‎ ee SUR ee hed ante gene deen ate] [9 eee ec ee 0 ener ae ane ae eed ped oe eed ee ee | ۱ ‏(0يا©) ممساة‎ ae en ee eee | 0 0 0 0 eee en eee ‏مئ‎ ‎01710700710101 et cee 

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Advanced Ceramics = Structural: Wear parts, bioceramics, cutting tools, engine components, armour. ® Electrical: Capacitors, insulators, integrated circuit packages, piezoelectrics, magnets and superconductors ™ Coatings: Engine components, cutting tools, and industrial wear parts bn OTTO Ieee] ‏ركاعغ‎ ‎membranes, catalysts, and catalyst supports 

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Engine Components Rotor | ۳ (ةصتمصسلة) دوهع 

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Turbocharger 5 Rotor 

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Ceramic Brake Discs +- 

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McLaren Mercedes Benz 

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Silicon Carbide Automotive Components in Silicon Carbide Chosen for its heat and wear gettin Tales) 

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Ceramic - Composite Armor aN 

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Silicon Carbide Body armour and ‏وخلوقك‎ ‎components ‎chosen for their ‏هفرعت[‎ ‎properties. 

Ceramics Ceramics A wide-ranging group of materials whose ingredients are clays, sand and felspar. Clays Contain some of the following:  Silicon & Aluminium as silicates  Potassium compounds  Magnesium compounds  Calcium compounds Sand contains Silica and Feldspar or Aluminium Potassium Silicate. Types of Ceramics      Whitewares Refractories Glasses Abrasives Cements Comparison metals v ceramics Metals Ceramics Bonded Clay Ceramics Made from natural clays and mixtures of clays and added crystalline ceramics. These include:  Whitewares  Structural Clay Products  Refractory Ceramics Whitewares      Crockery Floor and wall tiles Sanitary-ware Electrical porcelain Decorative ceramics Whiteware: Bathrooms Slip Casting Sinte r and Serv e Whitewares 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. Refractories  Used 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. Refractory Brick 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. Glass Types Three common types of glass:  Soda-lime glass - 95% of all glass, windows containers etc.  Lead glass - contains lead oxide to improve refractive index  Borosilicate - contains Boron oxide, known as Pyrex. Glasses      Flat glass (windows) Container glass (bottles) Pressed and blown glass (dinnerware) Glass fibres (home insulation) Advanced/specialty glass (optical fibres) Glass Containers Pressed Glass Processing Softened Gob Blow Molding Softened glass Glass in Buildings Plate Glass Drawing Processes Tempered Glass Small Scratches The strength of glass can be enhanced by inducing compressive residual stresses at the surface. The surface stays in compression - closing small scratches and cracks. Hardening Processes  Tempering: – Glass heated above Tg but below the softening point – Cooled to room temp in air or oil – Surface cools to below Tg before interior – when interior cools and contracts it draws the exterior into compression.  Chemical Hardening: – Cations with large ionic radius are diffused into the surface – This strains the “lattice” inducing compressive strains and stresses. Armoured Glass  Many 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!! Leaded Glass Crystalline Ceramics Good electrical insulators and refractories.  Magnesium Oxide is used as insulation material in heating elements and cables.  Aluminium Oxide  Beryllium Oxides  Boron Carbide  Tungsten Carbide.  Used as abrasives and cutting tool tips. Abrasives   Natural (garnet, diamond, etc.) Synthetic abrasives (silicon carbide, diamond, fused alumina, etc.) are used for grinding, cutting, polishing, lapping, or pressure blasting of materials Cements  Used to produce concrete roads, bridges, buildings, dams. Advanced Ceramics  Advanced 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 Advanced Ceramics     Structural: Wear parts, bioceramics, cutting tools, engine components, armour. Electrical: Capacitors, insulators, integrated circuit packages, piezoelectrics, magnets and superconductors Coatings: Engine components, cutting tools, and industrial wear parts Chemical and environmental: Filters, membranes, catalysts, and catalyst supports Engine Components Rotor (Alumina) Gears (Alumina) Turbocharger Ceramic Rotor Ceramic Brake Discs McLaren Mercedes Benz Silicon Carbide Automotive Components in Silicon Carbide Chosen for its heat and wear resistance Ceramic Armour  Ceramic 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.  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. Ceramic - Composite Armor Out er hard skin CeramicDiscont inuous Project ile Personnel and Equipment Inner duct ile skin Ceramic Armor Syst em Silicon Carbide Body armour and other components chosen for their ballistic properties.