Six Engineering Ceramics,
One Selection Standard

General wear and electrical insulation call for alumina: chemical resistance at economical cost. Impact-loaded parts call for zirconia, the highest fracture toughness of the range. Abrasion at temperature calls for silicon carbide, the highest hardness of the range and thermal shock resistance. Structural load under thermal cycling calls for silicon nitride, combining high strength with toughness. Heat removal with electrical isolation calls for aluminum nitride, the highest thermal conductivity of the range. Machinable, non-wetting fixture parts call for boron nitride, which can be machined with conventional tooling. Where two requirements conflict, the review states which requirement the recommended material favours and what is sacrificed.

Where a drawing does not name a material, the selection is made during the engineering review: the review names the material that carries the dominant requirement, states the trade-off it accepts and the route it forces, and that recommendation comes with the quotation so the price can be read against it. Where the drawing already fixes a material and a grade, the review works to that and states what the fixed choice gives up elsewhere. Sending the drawing with the operating conditions – temperature, load, medium and cleanliness – is what makes the recommendation specific rather than generic.