1 / 18

Classification of ceramics

Classification of ceramics. What a ceramic is ? From Greek word “ keramos ” (pottery, potter’s clay) Inorganic nonmetallic materials obtained by the action of heat and subsequent cooling

ronda
Download Presentation

Classification of ceramics

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Classification of ceramics

  2. What a ceramic is ? • From Greek word “keramos” (pottery, potter’s clay) • Inorganic nonmetallic materials obtained by the action of heat and subsequent cooling • Polycrystalline materials, single phase or multiphase (composites), sometimes with an amorphous component (glass) • Traditional ceramics • Whitewares: tableware, cookware, sanitary ware, etc. • Refractories (kiln and furnace linings for steel and glass industry) • Structural clay products (floor & roof tiles, bricks, etc.) • Fabricated from clay, quartz, feldspar (earthenware) and kaolin (porcelain) • Technical/advanced ceramics • Structural ceramics (mechanical properties: strength, toughness, hardness, creep resistance) • Functional ceramics (electric, magnetic, optical properties)

  3. Structural ceramics • Si3N4: bearing balls, cutting tools, heat exchangers, turbocharger rotors, parts of gas turbines • SiC: abrasives, disk brakes, pipes for corrosive liquids, ballistic armors • WC, Ti(C,N): cermets, inserts for cutting tools • B4C: neutron absorber in nuclear plants, ballistic armors, nozzles, abrasives • Al2O3 (alumina): spark plugs, substrates, crucibles, furnace tubes, ballistic armors, thermal insulation • 3Al2O3•2SiO2(mullite) & Mg2Al3(Si5AlO18) (cordierite): catalytic converters, ceramic filters • ZrO2 (zirconia): knifes, watch cases, orthopedic implants, grinding media, thermal barrier coatings • UO2: nuclear fuel • Ca10(PO4)6(OH)2 (hydroxyapatite): biomedical implants, artificial bone

  4. Ceramic Si3N4 bearing parts Ceramic body armour plates Radial rotor made from Si3N4 for a gas turbine engine The Porsche Carrera GT's silicon carbide disk brake Two Kyocera ceramic knives

  5. Functional ceramics

  6. Functional ceramics

  7. Thick (left) and thick (right) substrates (alumina) Pressed and extruded parts (alumina, mullite, zirconia) Microwave dielectric components Ferrites cores

  8. Microstructure of ceramics

  9. Ceramic microstructures SSS 99% Al2O3 – transparent fully dense (“ideal”) ceramic: grains + grain boundaries SSS 99% Al2O3 - ceramic with residual porosity: grains + g.b. + pores LPS 96% Al2O3 - dense ceramic with grain boundary glass phase: grains + glassy phase (CaO*SiO2) + 2 types of g.b.

  10. Microstructural variables • Density • - crystallographic (from unit cell parameters) • - theoretical (zero porosity, takes into account real composition) • - apparent (geometrical) density (< theoretical) • - relative density = (apparent/theoretical)*100 •  Porosity • - closed (only closed above 93% r.d.) • - open (pore networks connected to the surface) • - intragranular • - intergranular •  Grain size (simplest method: mean intercept length) •  Grain size distribution (monomodal, bimodal, abnormal grain growth) • Grain shape (equiaxed, elongated, prismatic, columnar, tabular, platelets) • - aspect ratio (ratio longest/shortest size dimensions) • Extended defects (dislocations, stacking faults, twins, domain walls) •  Second phase composition, shape and distribution •  Texture (grains oriented in a preferential direction)

  11. Intergranular porosity Intragranular porosity Types of porosity Y2O3:ZrO2 (PSZ) ceramic Intra- and intergranular porosity Ba(Ti,Ce)O3 ceramic Closed (intragranular) and open (itergranular channels) porosity

  12. Concave pore Convex pore Irregular pore associated with a hard agglomerate Shape of grains and pores gb 120° gb gb Equilibrium shape of grains. Hexagons (2D) and truncated octahedron (3D)

  13. Grain size distributions and abnormal grain growth 1450°C/2 h Equiaxed grains with monomodal distribution 1500°C/2 h Some large elongated grains appear: onset of AGG 1550°C/2 h Bimodal distribution related to AGG Mg0.1Al1.8Ti1.1O5 ceramics

  14. Revealing microstructure Fractography Polished surface Grain pull-out Cross-sections of Ba(Ti,Zr)O3 ceramics

  15. Si3N4 SiC Er-doped BaTiO3 Revealing microstructure Thermal etching Chemical etching Vapour Solid grain Solid grain After polishing Fully-dense alumina After thermal treatment

  16. Revealing microstructure Optical microscopy in polarized light Coated Co:WC:Ti(C,N) cermets

  17. Al2O3-(Zr,Y)O2 composite The darker phase is alumina Ba(Ti,Ce)O3 ceramic containing Ce-rich inclusions Revealing microstructure Scanning electron microscopy using backscattered electrons (BEI) Secondary phases in Er-doped BaTiO3 White phase: Er2Ti2O7 Dark gray phase: Ba6Ti17O40

More Related