Modeling and microstructural modification of alumina ceramic for improved tribological properties

Very simplified models were deduced for identifying important factors influencing friction and wear of ceramics in unlubricated sliding contact. Based on the theoretical predictions, laser surface alloying was used for modifying alumina ceramic by adding hafnia. Tribological tests were run on the modified ceramic, monolithic alumina and two different cutting ceramics on the base of alumina under conditions of unlubricated reciprocating sliding motion against Al₂O₃ balls. The friction coefficient and linear wear of the sliding pairs were substantially reduced and the transition from mild to severe wear shifted to higher applied surface pressure for the microstructurally modified ceramic compared with the monolithic alumina or the cutting ceramics, respectively.