Characteristics of Ceramic Materials: A P-by-P Selection Guide
Updated: Aug 27
Written by: Gulzar Hussain · Reviewed by: Mark Ma Last updated: August 26, 2026 · 9 min read
Who this is for: engineers deciding whether a ceramic is even the right material class for an application, and if so, which characteristic matters most for their specific design constraint.
Why it exists: "ceramics are hard and brittle" is true but not actionable. This page ties each characteristic to a sourced value across the six materials MAC machines most, so you can compare against your actual requirement — a load, a temperature, a voltage — rather than a general reputation.
Quick answer: Ceramic materials are defined by a consistent set of characteristics — high hardness, brittleness, low tensile-to-compressive strength ratio, thermal and electrical insulation, and chemical inertness — but the degree of each varies significantly by material and grade. Selecting a ceramic means matching the specific characteristic your application depends on to a material and grade that delivers it, not assuming all ceramics behave the same.
For the atomic and crystal-level mechanisms behind these characteristics, see structure of ceramic materials. This page is about the resulting properties and how to compare them.
Mechanical Characteristics
Direct answer: Ceramics are hard, resist compressive loads well, and tolerate almost no plastic deformation — meaning they fail by fracture rather than bending, and design margins need to account for that difference from metals.
Material | Flexural strength (MPa) | Fracture toughness (MPa·m^0.5) | Vickers hardness |
Alumina, 96% | 345 | 3.5 | ~1,100 kg/mm² |
Alumina, 99.5% | 379 | 4.0 | ~1,440 kg/mm² |
Zirconia (3Y-TZP) | ~1,000–1,240 | ~7–13 | ~12–13 GPa |
Silicon carbide (sintered) | 550 | 4.6 | ~2,800 kg/mm² |
Silicon nitride | 680 | 6.1 | ~15 GPa |
Boron carbide | — | ~3.5 | ~38 GPa |
Sources: Accuratus alumina and SiC datasheets; Precision Ceramics PCSN1000 (Si₃N₄) datasheet; Technical Products Inc. and Great Ceramic zirconia data; compiled reference data for boron carbide. Values are typical, grade-dependent — request a datasheet for your specific grade.
The standout number in that table is zirconia's fracture toughness — several times higher than alumina's. That's not a general "ceramics are tougher than you think" fact; it's specific to zirconia's transformation-toughening mechanism, and it's why zirconia gets specified for parts under cyclic mechanical load where alumina would be prone to chipping.
What this means for design: ceramics carry load well in compression and poorly in tension or bending under shock. If your application involves impact loading or tensile stress concentration, fracture toughness — not hardness — is the number to optimize for.
Thermal Characteristics
Direct answer: Thermal behavior varies more across ceramic materials than almost any other property — silicon carbide conducts heat about 50× better than zirconia — so "ceramics are good thermal insulators" is true for some materials and false for others.
Material | Thermal conductivity (W/m·K) | Max use temp (°C) | CTE (×10⁻⁶/°C) |
Alumina, 96% | 25 | 1,700 | 8.2 |
Alumina, 99.5% | 35 | 1,750 | 8.4 |
Zirconia (3Y-TZP) | ~2.2 | ~1,000 (structural ceiling) | — |
Silicon carbide | 120 | 1,650 | 4.0 |
Silicon nitride | 25 | — | 1.4 |
Aluminum nitride | 170–230 | — | matched to silicon |
Sources: Accuratus alumina and SiC datasheets; Precision Ceramics Si₃N₄ datasheet; MARUWA AlN substrate data; zirconia structural-use ceiling from prior MAC materials research.
What this means for design: if you need to dissipate heat, silicon carbide or aluminum nitride — not alumina or zirconia — are the candidates. If you need to block heat transfer, zirconia's low conductivity is an asset, not a limitation. Reading "ceramic" as a single thermal profile is the most common material-selection mistake we see.
Electrical Characteristics
Direct answer: Most oxide ceramics are strong electrical insulators; the covalent, non-oxide ceramics vary — silicon carbide can be semiconducting, while aluminum nitride and silicon nitride remain insulating despite their covalent bonding.
Material | Dielectric strength (kV/mm) | Electrical behavior |
Alumina, 96% | 14.6 | Insulator |
Alumina, 99.5% | 16.9 | Insulator |
Zirconia | ~33 | Insulator (also ionic conductor when doped for that purpose) |
Silicon carbide | — | Variable — can be engineered semiconducting |
Silicon nitride | ~15 | Insulator |
Aluminum nitride | — | Insulator, high thermal conductivity |
Sources: Accuratus alumina datasheets; Heeger Materials zirconia data; CeramicSpeed Si₃N₄ dielectric data.
What this means for design: if your application needs both electrical insulation and high thermal conductivity in the same part — a common power-electronics requirement — aluminum nitride is usually the answer, since alumina insulates but conducts heat poorly, and most high-conductivity ceramics (SiC) don't insulate as reliably.
Chemical & Corrosion Resistance
Direct answer: Technical ceramics generally resist acids, bases, and molten metals far better than most engineering metals, which is why they show up in valve components, crucibles, and semiconductor process equipment — but resistance still varies by material and by the specific chemistry involved.
Silicon carbide and high-purity alumina are the most broadly chemical-resistant of the six materials covered here, which is part of why both appear repeatedly in semiconductor and fluid-control applications (see our applications guide for specifics).
Chemical resistance isn't a single number the way hardness or conductivity is — always confirm against the actual process chemistry your part will see, since "chemically resistant" claims on a datasheet are typically qualified by test conditions.
Brittleness: The Trade-Off Behind Every Other Characteristic
Every characteristic above comes with the same asterisk: ceramics don't yield before they fail. There's no plastic deformation zone to absorb an overload or a stress concentration the way there is in metal — see the structure of ceramic materials for the atomic-bonding reason why. In practice, this means:
Design to keep ceramic components in compression where possible
Avoid sharp internal corners and sudden cross-section changes, which concentrate stress
Surface condition matters as much as bulk material — a machining scratch can measurably reduce a part's effective strength
Impact and shock loading favor higher-fracture-toughness materials (zirconia, silicon nitride) over harder but more brittle ones (alumina, boron carbide)
Choosing a Material by Primary Characteristic
Submit a drawing for engineering review → if you're ready to move from selection to a quote. Otherwise, the applications guide walks through material choice by industry rather than by property.
Frequently Asked Questions
What are the main characteristics of ceramic materials?
High hardness, brittleness (low tolerance for tensile or shock loading), high compressive strength, thermal and electrical insulation in most oxide ceramics, and strong chemical/corrosion resistance — though the degree of each varies significantly by specific material and processing grade.
Why are ceramics brittle?
Ceramic atomic bonding (ionic and covalent) restricts the dislocation movement that allows metals to deform plastically under load, so ceramics accumulate stress at flaws until they fracture rather than bending. See structure of ceramic materials for the full mechanism.
Which ceramic material is toughest against impact or shock loading?
Zirconia (3Y-TZP) has the highest fracture toughness of the common technical ceramics, several times that of alumina, due to its transformation-toughening mechanism — making it the usual choice where a ceramic must survive cyclic or impact loading.
Are all ceramics electrical insulators?
No. Most oxide ceramics (alumina, zirconia) and several non-oxides (silicon nitride, aluminum nitride) are strong insulators, but silicon carbide can be engineered to be semiconducting depending on composition and processing.
How does purity affect a ceramic's characteristics?
Higher purity generally raises dielectric strength, flexural strength, and thermal conductivity while typically increasing cost — see our composition of ceramic materials guide for how purity grade should factor into your specification.
Further Reading
Structure of Ceramic Materials — the atomic and microstructural mechanisms behind these characteristics
Applications of Ceramic Materials — material selection by industry
Ceramic Materials Guide — full properties, types, and applications overview
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