The Complete Guide to Technical Ceramics

Technical (advanced/engineering) ceramics are inorganic, non-metallic materials engineered for extreme temperature, wear, electrical insulation, corrosion resistance, and dimensional stability. Common families include alumina, zirconia, silicon nitride, silicon carbide, steatite/cordierite, glass-ceramics, and functional ceramics (piezo, ferrite, dielectric). This guide covers materials, properties, manufacturing, joining, quality tests, applications, and selection tips.

Table of Contents

1. What are technical ceramics?

2. Material families & where each shines

3. Properties that matter (mechanical, thermal, electrical, chemical)

4. Manufacturing processes (from powder to part)

5. Design for manufacturability (DfM)

6. Joining & metallization (ceramic-to-metal, glass-to-metal, brazing)

7. Quality assurance & testing

8. Industries & application examples

9. How to select the right ceramic (decision flow + checklist)

10. FAQ

What Are Technical Ceramics?

“Technical ceramics” (aka advanced or engineering ceramics) are purpose-designed ceramic compositions with controlled microstructures. Unlike traditional clay ceramics, they’re optimized for precision components in electronics, energy, semiconductor, medical, aerospace, and industrial equipment.

Material Families & Where Each Shines

Tip: If you need hermeticity or CTE matching to metals, consider glass-ceramics or sealing glasses engineered for stainless/Kovar and vacuum processing.

Properties That Matter

• Mechanical: Hardness, flexural/compressive strength, fracture toughness, wear.

• Thermal: Thermal conductivity (SiC high, ZrO₂ low), coefficient of thermal expansion (CTE), max service temperature, thermal-shock resistance.

• Electrical: Volume resistivity, dielectric strength, dielectric constant/loss, ESD behavior.

• Chemical: Corrosion/oxidation resistance in acids/alkalis, steam, molten salts, vacuum.

• Surface/finish: Porosity, RA, grain size—critical for seals, sliding pairs, and vacuum parts.

Rule of thumb: Zirconia for toughness, SiC for heat + wear, Si₃N₄ for thermal shock, Alumina for general-purpose insulation.

Manufacturing Processes (From Powder to Part)

1. Powder prep: Milling, spray-dry granulation, binders/dispersants; tight PSD for packing density.

2. Forming:

   • Uniaxial/CIP pressing for disks, rings, blocks.

   • Extrusion for tubes, rods, honeycombs.

   • Tape casting for sheets, substrates, multilayer stacks.

   • Ceramic Injection Molding (CIM) for complex 3D shapes with fine features.

3. Green machining: Drilling, turning, slots while binder is present (lower tool wear).

4. Debind & Sinter: Pressureless sintering, hot pressing, HIP, or SPS depending on density/toughness targets.

5. Post-machining: Diamond grinding, lapping, polishing; tight tolerances achievable on critical faces.

6. Surface engineering: Glazing, porous layers, metallization (see §6), laser features, cleaning for vacuum service.

Design for Manufacturability (DfM)

• Avoid sharp corners → add fillets/chamfers to reduce stress risers.

• Uniform wall thickness and gradual transitions; ceramics dislike thick-to-thin steps.

• Think shrinkage (varies by process/material); dimension drawings should state “after sinter” or give % shrink.

• Through-holes & slots: Respect minimum land/edge distances; align holes with pressing direction when possible.

• Surface specs: Call out RA/flatness only where needed; polishing is costly.

• Tolerances: Tighten only on functional faces; retain generous tolerances on non-critical features to improve yield/cost.

Joining & Metallization

Ceramic-to-Metal & Hermetic Packages

• Metallization systems:

  • Mo-Mn (or W-Mn) fired in wet H₂/N₂ → Ni/Au plating → solder/brazeable pads.

  • Direct (active) brazing with Ag-Cu-Ti or similar where metallization isn’t desirable.

• Glass-to-metal / Ceramic-to-metal seals:

  • Use lead-free, low-temperature sealing glasses to join to stainless/Kovar while matching CTE and protecting the ceramic.

  • Typical vacuum-processing windows are in the ~520–600 °C range depending on chemistry (e.g., phosphate vs. bismuthate systems).

• Design notes: Keep joint in compression; manage CTE mismatch; specify helium-leak limits for hermetic parts.

Soldering, Brazing, Adhesives

• Solder for low-temp, non-structural joints (onto plated pads).

• Braze for structural/hermetic joints; choose filler by service temp and chemistry.

• High-temp epoxies for non-hermetic assemblies when repairability is desired.

Quality Assurance & Testing

• Dimensional & visual: GD&T on critical faces, edge chips, cracks, glaze coverage.

• Density/porosity: Archimedes, micrographs.

• Mechanical: Flexural strength, hardness, fracture toughness; thermal-shock test if relevant.

• Thermal: CTE, thermal conductivity, max service temp validation.

• Electrical (if applicable): Volume resistivity, dielectric strength/constant/loss.

• Hermeticity: Helium leak test (e.g., 1×10⁻⁹ Pa·m³/s class for stringent seals); vacuum hold.

• Cleanliness: Ionic contamination/particle levels for semiconductor or vacuum hardware.

• Certifications: ISO 9001 / IATF 16949 for automotive; RoHS/REACH for materials compliance.

Industries & Application Examples

• Semiconductor & vacuum: Electrostatic chucks, wafer handling, insulators, heater plates, hermetic feedthroughs.

• Electronics & power: Metallized ceramics, LTCC/HTCC packages, heat-spreading substrates, dielectric resonators.

• Energy & EV: Pump/valve seals, bearings, battery glass-to-metal seals, thermal management components.

• Medical & life science: Dental burs, surgical tools, housings that require sterilization and biocompatibility.

• Aerospace & defense: Hot-section components, radomes, inertial sensors, ruggedized feedthroughs.

• Industrial: Mechanical seals, nozzles, guides, wear plates, steatite insulators, cordierite fixtures.

Selecting the Right Ceramic

Fast flow:

1. Environment: Temperature, chemicals, vacuum/pressure?

2. Function: Insulate, conduct heat, resist wear, or bear load?

3. Loads: Static vs. impact; thermal gradients/thermal shock?

4. Geometry: Simple ring/plate or complex 3D (CIM)?

5. Interfaces: Does it join to metal (hermetic or not)?

6. Regulatory: Biocompatibility, food contact, automotive, RoHS/REACH.

Buyer checklist to put in RFQs

• Material family/grade (e.g., 99.5% alumina, Y-TZP, SSiC, Si₃N₄, steatite, cordierite).

• Drawing with target after-sinter dimensions & tolerances.

• Surface specs (faces needing RA/flatness), porosity limits, cleanliness class.

• Quantity, annual volume, packaging/cleaning requirements.

• If hermetic: metallization stack, braze alloy, leak-rate target, CTE mate material.

• Any test methods and certificates required.

FAQ

Q1: Technical ceramics vs. traditional ceramics—what’s the difference?
Advanced ceramics are engineered for performance (purity, controlled grains), enabling high strength, insulation, and chemical resistance not typical of traditional clay products.

Q2: Which ceramic is best for sliding/wear at high temperature?
SiC excels for combined heat + wear + corrosion; Si₃N₄ is great where thermal shock is severe. Use polished or lapped faces and proper counterface materials.

Q3: I need a tough, damage-tolerant part.
Choose zirconia (Y-TZP/PSZ) for the highest fracture toughness among common ceramics.

Q4: What if I must braze the part to stainless or Kovar?
Specify Mo-Mn metallization with Ni/Au plating, or active brazing. For hermetic packages, lead-free low-temperature sealing glasses can join ceramic to metal while protecting vacuum integrity.

Q5: Can technical ceramics be injection-molded?
Yes—CIM produces complex shapes cost-effectively at volume; account for shrinkage and plan critical surfaces for post-grind.