Yttria-stabilised zirconia (Y-TZP) is the toughest of the oxide ceramics, with fracture toughness reaching 8–10 MPa·m^1/2 and flexural strength up to 1200 MPa. That combination lets it survive impact and side-loading that would shatter alumina or silicon carbide, which is why it shows up in knife blades, pump sleeves, ball heads and any application where a ceramic part takes mechanical abuse.
Zirconia also carries the lowest thermal conductivity of the structural ceramics discussed here (2–3 W/m·K), making it a natural thermal barrier. Its density (~6 g/cm³) is higher than alumina, so weight-sensitive designs favour lighter alternatives, but when toughness is the deciding factor zirconia is usually the answer.
