1. Define the duty before comparing materials
A material name alone does not define performance. Start with the operating envelope and the failure you need to prevent.
- Record continuous and peak temperatures, heating/cooling rate and atmosphere.
- Identify the fluid or gas, concentration, contaminants and cleaning chemicals.
- Describe contact load, impact, sliding speed, abrasive particles and expected duty cycle.
- For electrical parts, specify working voltage, insulation requirements and the complete thermal path.
2. Separate essential constraints from preferences
Eliminate unsuitable candidates first. A high wear score cannot compensate for inadequate electrical insulation or an unqualified temperature range.
- SiC is a candidate for wear and seal components; do not assume it is electrically insulating.
- Alumina and AlN can provide electrical insulation. Compare thermal performance using the actual grade and geometry.
- Si3N4 is a candidate where mechanical reliability and thermal cycling matter; confirm the specific grade and environment.
- For every candidate, check chemical compatibility and atmosphere rather than relying on a generic corrosion label.
3. Compare like-for-like data
Published properties are screening references, not interchangeable purchase specifications.
- Record the grade, density, process route and test temperature beside each value.
- Compare strength only with the test method and specimen preparation identified.
- For substrates, distinguish the bare ceramic from the complete copper/ceramic stack.
- Confirm dimensional tolerances, flatness, surface finish and inspection criteria on the drawing.
4. Qualify the component, not only the material
Use the first technical discussion to agree what must be measured and tested before production approval.
- Share the current part, failure photographs and critical drawing features.
- Agree sample quantity, inspection points and trial operating conditions.
- Record the acceptance criteria and any limits of the trial.
- Use approved drawings and grade-specific specifications for the order.