Compendium

Ceramics Taxonomy — Family Index

19 min read

Ceramics Taxonomy — Family Index

1. At a glance

Engineering ceramics are inorganic, non-metallic, predominantly ionic/covalent-bonded crystalline or amorphous solids. The functional taxonomy splits as follows:

  • Oxide ceramics — Al₂O₃ (alumina), ZrO₂ (zirconia), SiO₂ (silica), MgO (magnesia), BeO (beryllia, toxic dust), Y₂O₃ (yttria), TiO₂ (rutile/anatase).
  • Non-oxide ceramics — SiC (silicon carbide), Si₃N₄ (silicon nitride), B₄C (boron carbide), BN (boron nitride, hex + cubic), AlN (aluminum nitride), WC (tungsten carbide), TiC, TiN, TiCN.
  • Glasses and glass-ceramics — Macor (machinable mica-glass-ceramic), Zerodur (LiAlSi-O glass-ceramic), Pyrex/Borofloat (borosilicate), Gorilla Glass (aluminosilicate), fused silica.
  • Refractories — fireclay, high-alumina brick, mullite, magnesia brick, chrome-magnesia, ceramic-fiber blanket.
  • Transparent ceramics — sapphire (single-crystal Al₂O₃), ALON (aluminum oxynitride), spinel MgAl₂O₄, Y₂O₃, YAG.
  • Bioceramics — hydroxyapatite (HA), β-TCP, 45S5 Bioglass, Y-TZP for dental.
  • Functional/electronic ceramics — PZT, BaTiO₃, ferrites, perovskites, LTCC.

Defining traits versus metals: ceramics are generally brittle (K_IC typically 2–10 MPa·√m vs. 50–100 for structural steel), exhibit very high hardness (HV 1500–4000 vs. 200–800 for hardened steel), retain strength at high temperature (T_service 1000–1800 °C typical), are chemically stable (most are corrosion-resistant in oxidizing and alkali environments), and have low thermal-expansion coefficients (α ≈ 3–10 × 10⁻⁶ /K). Failure is flaw-size-dominated — strength is described statistically (Weibull modulus m ≈ 10–20).

2. Property cheat sheet

Ceramicρ (g/cm³)E (GPa)HV (kg/mm²)K_IC (MPa·√m)σ_flex (MPa)k (W/m·K)T_service,max (°C)Typical use
Alumina 99.5% (Al₂O₃)3.9038017004.5380301500Wear plate, substrates
Alumina 96%3.7231013003.5300241400Electrical insulators
Y-TZP (3Y-ZrO₂)6.0521013008.011002.5900Dental crowns, hip heads
Mg-PSZ (ZrO₂)5.75200120011.07002.01000Cam followers, dies
Cubic ZrO₂ (FSZ)5.9521013003.02502.22000Oxygen sensors
Fused silica (SiO₂)2.20736000.8501.41100UV optics, semiconductor
Borosilicate (Pyrex)2.23644800.75651.2500Labware, optics
Aluminosilicate (Gorilla)2.41716000.7900.9600Phone cover glass
Zerodur (Schott)2.53906200.9701.5600Telescope mirror blanks
Macor (Corning)2.52672501.5951.5800Machinable insulator
SiC (sintered, Hexoloy)3.1541028004.04601101600Seals, armor, kiln furniture
SiC (reaction-bonded, SiSiC)3.1038025003.53501301380Burner nozzles, heat exch.
Si₃N₄ (sintered)3.2531015006.5800281400Bearings, turbo rotors
Si₃N₄ (HIP’d)3.2532016008.0950301400High-load bearings
B₄C (boron carbide)2.5245033003.0350281600Body armor, neutron abs.
BN (hexagonal)2.275050 (anis.)1.510060900 (air)Solid lubricant, crucibles
c-BN (cubic)3.4872045005.0–2001100 (air)Cutting hard steels
AlN (aluminum nitride)3.2632012002.73201801400Power-electronic substrate
WC-6%Co (cemented carbide)14.9630160013.0220080800Cutting inserts, drills
TiC (titanium carbide)4.9347032004.0270211500Cermet cutting tools
TiN coating5.406002400––19600PVD tool coating
Sapphire (c-axis Al₂O₃)3.9840020002.5700351800IR domes, watch crystals
ALON (Surmet)3.6932018002.4380131200Transparent armor
Spinel (MgAl₂O₄)3.5828014501.9200151200Transparent armor, windows
Hydroxyapatite (HA)3.161006001.01001.01200Coating on implants

Values are representative of fully dense, room-temperature properties from CoorsTek, CeramTec, Kyocera, and Saint-Gobain datasheets. Real grades vary ±10–20 %.

3. Alumina (Al₂O₃)

Most-produced engineering ceramic by tonnage. Sold by purity grade:

  • 92 % Al₂O₃ — debased with glass phase; cheap insulators, fuse bodies.
  • 96 % Al₂O₃ — workhorse for spark-plug insulators (Bosch, NGK), thick-film substrates, wear tiles.
  • 99.5 % Al₂O₃ — high-strength wear plate (CoorsTek AD-995), high-vacuum feedthroughs, IC sockets.
  • 99.7 % / 99.9 % — semiconductor process parts (etch-chamber rings), bio-implant grade per ISO 6474.

Common product/grade names:

  • CoorsTek AD-995 — 99.5 % alumina; the de-facto reference grade in North America.
  • CeramTec Rubalit 708S — 96 % alumina substrate for thick-film hybrids.
  • Kyocera A-479B — 92 % alumina, electronic-grade.

Biomedical use: Al₂O₃ has been a successful femoral-head material since 1974 (CeramTec BIOLOX family, ISO 6474). Modern BIOLOX Forte is high-purity alumina; BIOLOX delta is zirconia-toughened alumina (ZTA) with ~24 % Y-TZP dispersion, ~80 % strength gain. Both are used in hip-resurfacing and total-hip arthroplasty.

Electronic substrates: Al₂O₃ is the dominant LTCC (low-temperature co-fired ceramic, ~850 °C, sintered with glass + Ag) and HTCC (high-temperature co-fired, ~1600 °C, sintered with W or Mo) substrate. LTCC: Dupont 951, Ferro A6M; HTCC: dominated by Kyocera. Power-module DBC substrates are usually 99.5 % Al₂O₃ or AlN.

4. Zirconia (ZrO₂)

Pure ZrO₂ undergoes destructive monoclinic→tetragonal transition at 1170 °C (~4 % volume change). Stabilization with MgO, CaO, Y₂O₃, or CeO₂ retains tetragonal or cubic phase to room temperature. Sub-grades:

  • PSZ (Partially-Stabilized Zirconia) — Mg-PSZ, Ca-PSZ, Y-PSZ. Tetragonal precipitates in cubic matrix → transformation toughening (K_IC up to 12 MPa·√m). Mg-PSZ (Nilcra TS-grade, now CoorsTek) is the historical engine-component grade — diesel cam followers, extrusion dies, oil-pump rotors.
  • FSZ (Fully-Stabilized Zirconia) — cubic, ~8 mol% Y₂O₃ (YSZ). Lower strength, but high ionic conductivity → solid-oxide-fuel-cell electrolyte, lambda sensor (O₂ sensor in every modern car).
  • Y-TZP (3Y-TZP) — 3 mol% Y₂O₃, ~100 % tetragonal, fine grain (~0.3 µm). Flexural strength 900–1200 MPa, K_IC 7–10 MPa·√m. The dominant dental crown (Sirona, 3M Lava, Vita YZ) and hip-ball-head material until the BIOLOX-delta ZTA hybrids took over.
  • Ce-TZP — Ce-stabilized; higher toughness but lower hardness than Y-TZP; orthopedic interest.

Low-temperature degradation (LTD / hydrothermal aging) is a well-known failure mode of 3Y-TZP exposed to water/saline at 30–300 °C. The metastable tetragonal phase transforms back to monoclinic at the surface, creating microcracks and roughness. The “Prozyr femoral-head recall” (2001, Saint-Gobain Desmarquest) was the canonical industrial example. Modern medical Y-TZP grades use finer grain, lower yttria gradient, and HIP’ing to suppress LTD; ISO 6474-2 specifies the accelerated aging test.

5. Silica and glasses

Fused silica (SiO₂) — amorphous, made from melted quartz or chemical-vapor-deposited (synthetic UV grade, e.g., Corning HPFS 7980, Heraeus Suprasil). High transmission from 175 nm (deep UV) to 2.5 µm (near-IR); extremely low thermal expansion (~0.55 × 10⁻⁶ /K); used in semiconductor lithography optics, fiber-optic preforms, IC-processing tubes.

Soda-lime glass — bulk window/container glass (Na₂O-CaO-SiO₂, ~72 % SiO₂). Float-process (Pilkington 1959) dominates flat-glass production.

Borosilicate (Pyrex, Borofloat, Duran) — ~80 % SiO₂ + B₂O₃ + Na₂O + Al₂O₃. Low α ≈ 3.3 × 10⁻⁶ /K → thermal-shock resistant; lab glassware, cookware, telescope mirror blanks. Schott Duran/Borofloat 33, Corning Pyrex 7740, Owens-Illinois Kimax.

Aluminosilicate (chemically-strengthened cover glass) — Corning Gorilla Glass (5/6/Victus), AGC Dragontrail, Schott Xensation. Ion-exchanged in molten KNO₃ → Na⁺ replaced by larger K⁺ → ~700 MPa compressive surface; used as phone/tablet/laptop cover glass.

Glass-ceramics are crystalline materials produced by controlled devitrification of a parent glass. Notable products:

  • Schott Zerodur — LiAlSi-O parent, β-eucryptite crystallites. CTE ≈ 0 ± 0.05 × 10⁻⁶ /K at 20 °C → telescope-mirror blanks (Keck, VLT, ELT). Successor competitor: Corning ULE 7972 (TiO₂-doped silica, slightly different mechanism).
  • Corning Macor — fluorphlogopite-mica glass-ceramic, ~55 % mica + 45 % borosilicate. Machinable with standard HSS taps and drills; tolerance ±25 µm; used for vacuum feedthroughs, lab fixtures, RF insulators.
  • Schott Ceran / Eurokera Kerablack — β-quartz-spinel glass-ceramics for radiant cooktops.
  • Corning Pyroceram — original 1957 cordierite glass-ceramic; CorningWare cookware origin.

6. Silicon carbide (SiC)

Covalent ceramic, multiple polytypes (3C-SiC cubic, 4H-SiC and 6H-SiC hexagonal). Major engineering forms:

  • Sintered α-SiC (SSiC) — pressureless sintered with B + C additives. Saint-Gobain Hexoloy SA, CoorsTek PureSiC. Highest purity, no free Si; chemical-pump seals, mechanical-seal faces, vacuum process parts.
  • Reaction-bonded SiC (RBSiC / SiSiC) — porous α-SiC preform infiltrated with molten Si. ~10–15 % residual free Si. Saint-Gobain Halsic-RX, Morgan Crystar. Lower cost, complex shapes; service limited to ~1380 °C (Si melts 1414 °C). Used for kiln furniture, burner nozzles, thin-walled heat exchangers, mirror blanks for space telescopes (Herschel was 3.5 m SiC).
  • CVD SiC — chemical-vapor-deposited polycrystalline, ~3.21 g/cm³, ~99.9995 %. Trex CVD SiC, Morgan/Coorstek CVD. Used for plasma-etch chamber components, optical-grade mirror substrates, mirror cladding on RBSiC core.
  • Recrystallized SiC (ReSiC) — sintered without densification additive; porous; for high-T kiln-furniture beams to 1650 °C.

SiC is also the dominant wide-bandgap power semiconductor in 2025: 4H-SiC (650 V, 1200 V, 1700 V MOSFETs and Schottky diodes) by Wolfspeed (Saint-Gobain CREE spin-off), Infineon, ROHM, STMicroelectronics, Onsemi (GTAT bulk crystal). Used in EV inverters (Tesla Model 3 was the first volume application, 2018) and DC fast-chargers.

7. Silicon nitride (Si₃N₄)

Among the toughest engineering ceramics (K_IC 6–10 MPa·√m via β-Si₃N₄ acicular grain interlocking). Processing variants:

  • SSN (Sintered Si₃N₄) — pressureless sintered with Y₂O₃/MgO/Al₂O₃ glass phase. Most general purpose.
  • HP-SN (Hot-Pressed) — uniaxial hot-press, full density, anisotropic; cutting-tool inserts.
  • HIP-SN (Hot-Isostatic-Pressed) — full density, isotropic, the high-end bearing-ball grade.
  • RBSN (Reaction-Bonded) — Si powder nitrided in N₂; net-shape, ~85 % dense, cheap, lower strength; thermocouple sheaths.
  • SRBSN (Sintered Reaction-Bonded) — RBSN preform post-sintered; intermediate cost/properties.

Industrial uses:

  • Bearing balls and rollers — NBD-200 (originally Norton/Saint-Gobain), Toshiba TSN-03NH, CeramTec SL grade, SKF Ceramic. Hybrid bearings (steel rings + Si₃N₄ balls) dominate machine-tool spindles, EV traction motors, dental hand-pieces, and turbomachinery. Si₃N₄’s low density (~40 % of bearing steel) reduces centrifugal load at high rpm; non-galling against steel rings.
  • Turbocharger rotors — CTS (Mitsubishi-Hitachi), Kyocera. Higher transient response than Inconel rotors due to lower rotational inertia.
  • Engine valves and tappets — limited production (race engines).
  • Cutting inserts — Si₃N₄ + Al₂O₃ “SiAlON” for milling cast iron at high speed; Kennametal KY1540, Sandvik CC6090.
  • Welding nozzles, glow plugs, ladle-stirrer wear parts.

8. Boron compounds

B₄C (boron carbide) — third-hardest material after diamond and c-BN (HV 3000–3500). Lowest density of the hard ceramics (2.52 g/cm³), which makes it the standard personal-armor insert: U.S. military ESAPI small-arms-protective-inserts (Ceradyne, now 3M; Saint-Gobain; Morgan). Also nuclear-control-rod material (high ¹⁰B neutron-absorption cross-section). Limitation: amorphization under high-velocity impact (>900 m/s with HEAT-style penetrators), and brittle catastrophic shatter.

BN (hexagonal, h-BN) — graphite-isomorph layered structure; very low friction; “white graphite” solid lubricant. Used as mold-release in glass forming, cosmetic powder, machinable BN (Saint-Gobain Combat, Momentive A-grade) for high-temperature electrical insulators, crucibles for II-VI melt growth. Oxidizes above ~900 °C in air.

c-BN (cubic boron nitride, “borazon”) — sphalerite-structure analog of diamond; HV ~4500; chemically stable against Fe (unlike diamond which carbides). Synthesized at >5 GPa, >1500 °C. As polycrystalline-CBN (PCBN) compacts on a WC substrate (Element Six Amborite, Sumitomo BNC-300, Mitsubishi MB825), CBN is the cutting-tool material for hard turning (HRC 55–65 steels, replacing grinding in many gear-, bearing-, and roller-finishing operations).

9. Carbides for tooling

Cemented tungsten carbide (WC-Co) is sometimes classified as a cermet (composite of ceramic + metal binder) but is the workhorse of industrial cutting and wear:

  • WC-6%Co — Sandvik H10F, Kennametal K313 — general-purpose milling/turning, dies, punches.
  • WC-10%Co — tougher, used for high-shock dies, snowplow tips.
  • WC-12%Co — rock-drill buttons, mining bits.
  • Submicron / ultrafine WC (Sandvik CB10) — high hardness for finishing inserts.

Other carbide cutting materials:

  • TiC and TiCN — used as components of cermets (Ni or Ni-Mo binder), cheaper than WC; CoorsTek, Plansee, Ceratizit.
  • TiAlN, TiCN, AlCrN, TiSiN coatings — PVD/CVD-deposited onto WC inserts; Oerlikon Balzers Balinit Alcrona Pro, Sandvik GC4325, Kennametal KCK20. Improve tool life 2–5×.
  • Cermets — TiC/TiN + Ni/Mo binder; finer finish than WC, cheaper than CBN; used for finish-turning steel.

10. Refractories

Materials with PCE (pyrometric-cone equivalent) > Orton cone 15 (~1430 °C):

  • Fireclay — Al₂O₃ 25–45 % + SiO₂; cheapest, kilns and chimneys to 1300 °C.
  • High-alumina — 50–90 % Al₂O₃; furnace linings, glass-tank crowns, to 1500–1800 °C depending on grade.
  • Mullite (3Al₂O₃·2SiO₂) — kiln-furniture posts, batts, saggars, kiln-car decks; excellent thermal-shock resistance. Suppliers: Saint-Gobain, CeramTec, AluChem.
  • Magnesia (MgO) basic brick — steel ladles, BOF (basic-oxygen-furnace) linings, EAF roof. Reacts with acidic slags only above 1700 °C; standard for steelmaking. RHI Magnesita, Vesuvius.
  • Chrome-magnesia — historically dominant for steel ladle; declining due to Cr⁶⁺ environmental concerns.
  • Zirconia refractories — AZS (alumina-zirconia-silica fused-cast) blocks line glass-melting tanks; Saint-Gobain SEFPRO ER 1681, Corhart. Long contact-time service to 1600 °C in molten glass.
  • Graphite + carbon — blast-furnace hearth, aluminum-reduction-cell cathode lining.
  • Ceramic-fiber blanket / board — alumino-silicate wool. Morgan Kaowool, Unifrax Fiberfrax, Isolite. Service to 1260 °C (Kaowool 1260) and 1400 °C (high-purity polycrystalline-alumina fibers, Saffil); used for kiln-door seals, exhaust-system heat shields, gas-turbine combustor liners (replaced by oxide-CMC in modern designs).

EU REACH and RAL classify RCF (refractory ceramic fiber) as Carc 1B — modern installations use low-bio-persistent AES (alkaline-earth silicate) wool, e.g. Morgan Superwool Plus rated to 1200 °C.

11. Transparent ceramics

Specialty optical-grade ceramics with grain size << wavelength (or single-crystal) → near-zero scatter:

  • Sapphire (single-crystal Al₂O₃) — Czochralski, EFG (Edge-defined Film-fed Growth), or Kyropoulos pulled. Suppliers: Kyocera, GTAT (now in Wolfspeed), Saint-Gobain, Rubicon. Used for IR missile domes (LOAL bandpass ~3–5 µm), high-pressure sight glasses, watch crystals (Rolex, Omega), LED epi substrates, smartphone camera covers.
  • ALON (Surmet) — Al-O-N spinel structure, polycrystalline transparent; HV ~1800, 4× harder than glass. Surmet in the U.S. (sole producer); transparent armor for U.S. military vehicle windows (HMMWV, JLTV); each laminate is ALON face-sheet + polycarbonate spall layer.
  • Spinel (MgAl₂O₄) — polycrystalline transparent; Surmet, Saint-Gobain. Cheaper than ALON; same transparent-armor application; also IR-dome candidate for high-speed missiles (better thermal-shock than sapphire).
  • Y₂O₃ (yttria) — IR window (transparent to ~8 µm), laser-host crystal substrate.
  • YAG (Y₃Al₅O₁₂) — Czochralski single-crystal; the Nd:YAG laser-rod host (1064 nm); ceramic-poly YAG (Konoshima, Baikowski) now competes with single-crystal in high-power solid-state lasers (Lockheed-Martin 60 kW HEL).
  • PLZT (Pb-La-Zr-Ti) — electro-optic transparent ceramic; flash goggles.

12. Bioceramics

Three biofunctional classes:

  • Bioinert — Al₂O₃ (BIOLOX), Y-TZP, zirconia-toughened alumina (BIOLOX delta). Hip-femoral heads, knee components, dental crowns. Per ISO 6474-1 (alumina), ISO 6474-2 (Y-TZP). Y-TZP dental: 3M ESPE Lava, Sirona CEREC inLab, Vita YZ.
  • Bioactive — forms hydroxyapatite-bond with bone in vivo:
    • Bioglass 45S5 (45 SiO₂ – 24.5 Na₂O – 24.5 CaO – 6 P₂O₅, wt%) — invented by Larry Hench at Univ. of Florida 1969; sold as NovaBone, PerioGlas (NovaBone Products / Stryker).
    • A-W (apatite-wollastonite) glass-ceramic — Cerabone (Kyocera), vertebral spacers in Japan.
  • Resorbable — dissolves and is replaced by new bone:
    • β-tricalcium-phosphate (β-TCP, Ca₃(PO₄)₂) — bone-void filler granules, putty, blocks. ChronOS (Synthes/DePuy), Vitoss (Stryker), Cerasorb (Curasan).
    • Calcium-sulfate (plaster-of-Paris derivatives) — Wright Medical Osteoset.
    • Biphasic HA/TCP — Triosite, MasterGraft (Medtronic).
  • Hydroxyapatite (HA, Ca₅(PO₄)₃OH) — plasma-spray coating on titanium hip-femoral stems and dental implants (BoneMaster on Biomet, Plasmapore on Aesculap); 50–100 µm thick, ~70 % crystallinity. Improves osseo-integration. Bulk HA is rarely used as load-bearing implant — too weak.

13. Piezoceramics and functional ceramics

  • PZT (Pb(Zr,Ti)O₃) — perovskite, dominant piezoelectric. Compositions tuned by Zr/Ti ratio near morphotropic phase boundary. Hard grades (PZT-4, PZT-8) for sonar transmitters, ultrasonic cleaning; soft (PZT-5A, PZT-5H) for actuators, hydrophones, medical ultrasound transducers. Suppliers: PI Ceramic, CTS Corporation (Channel Industries), APC International, TRS Technologies. EU RoHS exemption since 2017 (no commercial Pb-free equivalent yet — KNN and BCT-BZT are close).
  • BaTiO₃ — tetragonal perovskite; the foundational piezoelectric (Wainer, Salomon, von Hippel ~1942–46). Today the dominant MLCC (multi-layer ceramic capacitor) dielectric (X7R, X5R class-II) — Murata, TDK, Samsung Electro-Mechanics, Kyocera-AVX, Yageo. Capacitance density 100 nF/mm³ at 50 V class.
  • NPO/C0G dielectrics — temperature-stable, class-I, based on CaZrO₃/Nd-doped TiO₂; precision filters and timing.
  • Ferrites — soft Mn-Zn ferrite for SMPS transformer cores (TDK PC95, Ferroxcube 3F4), Ni-Zn ferrite for higher frequency (10–500 MHz); hard ferrite (Sr/Ba-hexaferrite) for permanent magnets and HDD platters.
  • SrTiO₃, CaTiO₃ — perovskite microwave dielectrics; LTCC fillers.
  • YBCO (YBa₂Cu₃O₇₋δ) — high-T_c superconductor (T_c = 92 K), now commercialized as 2nd-generation REBCO coated-conductor tape (American Superconductor, Faraday Factory, Theva) for MRI and fusion-magnet windings.
  • β-alumina (Na-β-Al₂O₃) — Na⁺ solid electrolyte for sodium-sulfur and ZEBRA (Na-NiCl) batteries.
  • YSZ (8YSZ) — solid-oxide-fuel-cell electrolyte, Bloom Energy server stacks; lambda-O₂ exhaust sensor.

14. Failure modes — comparison table

ModeMechanismMaterials affectedMitigation
Brittle fractureFlaw-driven Mode-I crack from surface/volume defect; Weibull m ≈ 10–20All ceramicsSurface finishing, proof testing, low tensile-stress design (compression OK), Weibull-statistical sizing
Slow crack growth (subcritical)Stress-corrosion at crack tip; n = dlnv/dlnK ≈ 20–50 for oxides, 50–100 for SiC/Si₃N₄Glass, Al₂O₃, Y-TZP especially in moist/salineLower stress, drier service, fatigue test in service environment
Hydrothermal aging (LTD)t→m transformation in 3Y-TZP at 30–300 °C in H₂O/saline3Y-TZP dental, hip-ballsFiner grain, HIP, higher Y₂O₃ at surface, ZTA composites (BIOLOX delta)
Thermal shockTensile stress on cooled surface; failure when Biot # × ΔT × E × α / σ_f > 1Glass, oxidesLower E, lower α, higher k, higher σ_f; pre-stressed surface (tempered glass)
OxidationNon-oxide → oxide at high T in airSiC (active <800 °C, passive >800 °C as protective SiO₂), Si₃N₄, B₄C, BNUse protective SiO₂ surface; coatings (mullite + Y-silicate for SiC-CMC); inert atmosphere
Alkali (NaOH, KOH) corrosionSiO₂ network attack; depletes silica from glassBorosilicate, silica fibersUse Al₂O₃, ZrO₂, MgO; or alumino-silicate glass
Abrasive wearHardness ratio vs. abrasiveLess-hard ceramics losing to SiC/Al₂O₃ slurryMatch HV > 1.2 × abrasive HV; SiC, Al₂O₃, B₄C wear plates
Erosion / impact spallingHertzian-cone cracking from particulate impactBrittle thin sectionsIncrease thickness, use tougher Si₃N₄ or ZTA, surface compression
Creep at high TGlass-phase softening at grain boundariesSintered Si₃N₄ with glassy phase, oxides above 0.5·T_mRefractory grain-boundary phase (Y-silicate, lutetium-silicate), or HIP without sintering aid

15. Selection heuristics

  • Bulk wear plate (chute liner, slurry pump volute) → Al₂O₃ 92–99.5 % tile (cheap, ample size) or sintered α-SiC (harder, more chip-resistant).
  • High-toughness machinable insulator (prototype RF feedthrough, vacuum-rig fixture) → Corning Macor; drill and tap with carbide HSS, no firing step.
  • Dental implant abutment, crown → Y-TZP (3M Lava, Sirona) or lithium-disilicate (e.s.s. IPS e.max).
  • Hip femoral head → BIOLOX delta ZTA (CeramTec) is the current standard; 99.7 % Al₂O₃ (Forte) still available for back-compat couples.
  • Ball valve / mechanical-seal face for slurry or hot-water → α-SiC (Hexoloy SA) or Si₃N₄ (CeramTec SL). SiC for abrasive slurry; Si₃N₄ where impact is a concern.
  • Body-armor rifle plate (Level IV) → B₄C insert (CeradyneM3M ESBI) or SiC (Saint-Gobain Hexoloy ESAPI) backed by UHMWPE/aramid spall layer.
  • Hypersonic-vehicle leading-edge window → sapphire (single-crystal Al₂O₃) for 3–5 µm IR, or ALON / spinel for visible + IR with shock survival.
  • Cutting hardened steel HRC 55–65 → CBN insert (Element Six Amborite DBN45, Sandvik CB7015); replaces grinding.
  • Cutting cast iron at high feed → SiAlON (Kennametal KY1540) or Al₂O₃-TiC ceramic (Sandvik CC650).
  • Thermal-protection re-entry tile → carbon-SiC CMC (Shuttle X-37 leading edges), or LI-2200 rigid silica-fiber insulation (the Shuttle white/black underside tile, ρ = 0.35 g/cm³, Lockheed Martin).
  • Flame-tube / boiler lining → mullite or 70 % Al₂O₃ firebrick; ceramic-fiber blanket back-up.
  • Ultrasonic transducer (medical, NDT) → PZT-5A (soft) for receive; PZT-4 / PZT-8 (hard) for high-power transmit; new PMN-PT single crystals (TRS) for premium broadband.
  • Power-module substrate (1200 V SiC MOSFET) → AlN-DBC for thermal performance (k = 180 W/m·K); Al₂O₃-DBC if cost-driven; Si₃N₄-AMB for high thermal cycling (best fracture toughness).
  • EV-traction-motor bearing (ball) → HIP Si₃N₄ ball (CeramTec SL grade) on tool-steel rings — electrically isolating, runs cooler.
  • Spark-plug insulator → 96 % Al₂O₃ (Bosch FR-series, NGK).

16. Vendors

  • CoorsTek (Golden, Colorado, USA) — largest technical-ceramics maker; full range alumina, zirconia, SiC, Si₃N₄, AlN; semiconductor process parts, armor, biomedical Y-TZP feedstock.
  • CeramTec (Plochingen, Germany) — BIOLOX bioceramics, SL Si₃N₄ bearings, Rocar SiC, Rubalit substrates.
  • Kyocera (Kyoto, Japan) — semiconductor packages (HTCC), MLCCs, dental Y-TZP (Cerabien), SiC/Si₃N₄.
  • Morgan Advanced Materials (Windsor, UK) — Halsic-RX RBSiC, Crystar SSiC, AlN substrates, BN solid-lubricant grades; Kaowool fiber.
  • Sumitomo Osaka Cement / Sumitomo Electric (Japan) — Si₃N₄ bearings, CBN tooling (BNC-300).
  • Saint-Gobain CREE / Wolfspeed — Wolfspeed (formerly CREE, formerly Saint-Gobain CREE) is now an independent SiC-semiconductor leader (Durham, NC); Saint-Gobain Ceramics still produces Hexoloy SSiC, NorBide B₄C, IRCON sintered Si₃N₄.
  • Schott AG (Mainz, Germany) — Zerodur, Borofloat 33, Pyrex equivalents, Xensation cover glass.
  • Corning Inc. (Corning, NY) — Gorilla Glass, Macor, Pyrex (now mostly under license for cookware), ULE 7972, optical-fiber preforms.
  • Element Six (De Beers subsidiary, UK/IE) — synthetic diamond (PCD), CBN (Amborite), CVD diamond windows.
  • AGC (Tokyo) — Dragontrail aluminosilicate cover glass, automotive glass.
  • Surmet Corporation (Burlington, MA) — sole ALON producer; spinel transparent ceramics.
  • TDK / Murata / Yageo — MLCC, soft-ferrite cores, PZT actuators.
  • PI Ceramic / CTS / APC — PZT actuators, ultrasonic transducers.
  • Ceradyne (3M) — B₄C armor; bought by 3M 2012.
  • Bloom Energy — YSZ-electrolyte SOFC stacks.

17. Processing routes — quick reference

Engineering ceramics are nearly always shaped from powder, then densified by sintering. The principal routes:

  • Dry pressing (uniaxial) — granulated spray-dried powder pressed in a steel die at 50–300 MPa. Tablets, substrates, simple disks. Fast, high-volume; aspect ratio limited to ~3:1 due to friction.
  • Cold isostatic pressing (CIP) — powder in elastomer bag, isostatic 100–400 MPa. Uniform green density, complex shapes; used as preforming step before sintering or HIP.
  • Slip casting — aqueous slurry poured into plaster mold; mold absorbs water; cast wall builds up. Complex hollow shapes (crucibles, kiln-furniture saggars, sanitaryware). Cycle time hours.
  • Tape casting (doctor-blade) — slurry on Mylar carrier, dried to flexible green tape 25–500 µm thick. The standard substrate / MLCC / LTCC process. Multilayer co-fire after stack-laminate-via-fill-print.
  • Extrusion — paste with cellulose binder forced through die. Honeycombs (auto-catalyst substrates — Corning Celcor cordierite), tubes, rods. NGK, Corning, Ibiden.
  • Injection molding (CIM) — powder in thermoplastic binder, injected like plastic; binder removed in solvent + thermal debind; sintered. Net-shape complex parts.
  • Additive manufacturing — binder-jet (ExOne), SLA-photopolymer with ceramic filler (Lithoz, 3DCeram), DIW direct ink writing. Aerospace cores, dental, micro-reactors.
  • Sintering — pressureless heat to 0.7–0.9 T_melt; diffusion densifies. Most economical.
  • Hot pressing (HP) — uniaxial press during heat (~30 MPa, 1500–2000 °C). Full density; one part per cycle; flat geometry only.
  • Hot isostatic pressing (HIP) — argon-pressurized (100–200 MPa) during heat. Full density, any geometry, expensive. Bearing-grade Si₃N₄ and Y-TZP usually HIP’d.
  • Reaction-bonding — Si₃N₄ from Si nitridation; SiC from Si infiltration of porous C/SiC preform; near-net-shape, ~85–95 % dense, lower properties than sintered.
  • CVD / CVI — chemical-vapor-deposited bulk SiC and BN; SiC infiltration of woven-fiber preforms for SiC/SiC CMC turbine parts (GE Aviation LEAP shrouds).
  • Sol-gel — alkoxide hydrolysis → gel → fire. Coatings, fibers, fine powders.

18. Cross-references

18. Citations

  • ASM Handbook, Vol. 4 — Ceramics and Glasses (ASM International, 1991, multiple later updates).
  • D. W. Richerson, Modern Ceramic Engineering: Properties, Processing, and Use in Design, 3rd ed., CRC Press, 2006.
  • D. Munz, T. Fett, Ceramics: Mechanical Properties, Failure Behaviour, Materials Selection, 2nd ed., Springer, 2001.
  • W. D. Kingery, H. K. Bowen, D. R. Uhlmann, Introduction to Ceramics, 2nd ed., Wiley, 1976 — still the canonical foundations text.
  • R. Morrell, Handbook of Properties of Technical and Engineering Ceramics, HMSO/NPL (Parts 1–2).
  • ISO 6474-1 (Alumina implants), ISO 6474-2 (Y-TZP implants), ISO 13356 (Y-TZP for surgical implants).
  • ASTM C1424 (compressive strength of advanced ceramics), ASTM C1499 (biaxial flexure of advanced ceramics, ring-on-ring), ASTM C1421 (K_IC of advanced ceramics, SEPB/SCF methods).
  • L. L. Hench, “The story of Bioglass,” J. Mater. Sci. Mater. Med. 17, 967–978 (2006).
  • J. Chevalier, “What future for zirconia as a biomaterial?” Biomaterials 27 (2006), 535–543 — LTD review.
  • The American Ceramic Society (ACerS) — https://ceramics.org/ — journals (J. Am. Ceram. Soc., Int. J. Appl. Ceram. Technol.), trade reference.
  • ISO — https://www.iso.org/ — TC 206 (Fine ceramics) standards portfolio.

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