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Why is alumina widely used as a wear-resistant ceramic?

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advanced structural ceramics Figure 1: Resistance to cracking in transformation-toughened zirconia. In a ceramic composed of tetragonal zirconia dispersed in a zirconia matrix, the stress field advancing ahead of a propagating crack transforms the small tetragonal particles to larger monoclinic particles. The larger particles exert a crack-closing force in the process zone behind the crack tip, effectively resisting propagation of the crack.

Alumina (aluminum oxide, ${Al}_{2} O_{3}$ ) is widely utilized as a wear-resistant ceramic primarily due to its exceptional hardness, which measures 9 on the Mohs hardness scale. This inherent hardness, derived from strong chemical bonding, allows it to effectively resist both impingement and rubbing wear in demanding industrial environments.1234

Beyond its hardness, alumina is favored for its:
* Low manufacturing costs: It is the most widely used tribological ceramic largely because it is more economical to produce than more advanced, toughened ceramic alternatives.4
* Chemical and thermal stability: It exhibits high resistance to chemical attack and maintains high strength and electrical resistivity at elevated temperatures, with a melting point of approximately 2,050 °C (3,700 °F).12

While alumina is susceptible to grain pullout—which can lead to surface roughening—its combination of durability, cost-effectiveness, and robust mechanical properties makes it a standard material for applications ranging from abrasives and grinding wheels to industrial refractory linings and pump components.142