Dependence of Tribological Characteristics on Mechanical Properties and Phase Transformations of Zirconia-Based Composite Ceramics

The effect of silica addition (in the concentration range of C-SiO2 from 0 to 6 mol %) to alumina toughened zirconia ceramics (stabilized in the tetragonal phase with calcium oxide) on its friction coefficient and wear intensity is investigated. It is found that with an increase in the SiO2 concentration, both characteristics undergo non-monotonic changes with a general tendency to increase. A comparative analysis of the dependences of mechanical properties (microhardness, fracture toughness and brittleness index), transformability of the tetragonal phase t-ZrO2, and wear intensity on the SiO2 content in the composite ceramics is performed. It is shown that the non-monotonic nature of the dependence of the wear intensity on the SiO2 concentration is due to the competitive effect of changes in microhardness, fracture toughness, and transformability of t-ZrO2 caused by the introduction of silicon dioxide into the ceramics. A proposal is made on the feasibility of producing silicon-containing ceramics (with increased fracture toughness and compressive strength, as well as a margin of ductility at room temperatures) with a surface layer that does not contain SiO2, retaining the preferred values of microhardness, friction coefficient, and wear intensity.