Abstract
<jats:p>Introduction. Oxide ceramics based on partially stabilized zirconium dioxide (PSZ) belong to the class of high-strength engineering materials used in structural products operating under conditions of increased mechanical loads and abrasive wear. The condition of the surface layer is of fundamental importance for structural products, since it is this layer that bears the main operational loads and determines resistance to wear and brittle fracture. The aim of this study is to establish a quantitative relationship between the phase composition and microhardness of the surface layer of ZrO2(5.4 wt.% Y2O3)–30 wt.% Al2O3 structural com-posite ceramic and the grinding depth under surface grinding conditions at a fixed longitudinal feed rate. Materials and methods. The object of the study was a composite ceramic with the composition ZrO2(5.4 wt.% Y2O3)–30 wt.% Al2O3. The billets were fabricated by cold isostatic pressing followed by sintering at 1580 °C. After sintering, the material exhibited a dense and homogeneous structure without visible macro-scopic defects. Rectangular parallelepiped specimens with dimensions of 25 × 5 × 3 mm were prepared from the sintered plates. Surface grinding was performed on an OSh-400 grinding machine using a 1A1 diamond wheel (400 × 40 × 6 × 203, AS6 200/160 M2-01 100%). The wheel peripheral speed was 40 m/s. The longitudinal table feed rate was maintained at 7.3 m/min for all processing modes. Cooling was provided by continuous wa-ter supply to the wheel–workpiece contact zone. Phase analysis was carried out by X-ray diffraction using CuKα radiation in the 2θ range of 24 – 36°, and quantitative phase evaluation was performed by the Rietveld refinement method. Microhardness was measured by the Vickers method under a load of 0.5 N. Results. The influence of grinding depth on the phase composition and microhardness of the near-surface layer of a ZrO2(5,4 wt.% Y2O3) - 30 wt. % Al2O3 composite ceramic was investigated under plane grinding conditions. Grinding was performed on an OSh-400 surface grinding machine using a 1A1 dia-mond wheel at a peripheral speed of 40 m/s and a longitudinal feed rate of 7.3 m/min. The grinding depth was varied within the range of 0.005–0.02 mm. It was established that an increase in grinding depth leads to a gradual increase in the monoclinic zirconia content in the near-surface layer from 31 % in the polished state to 41 % at a grinding depth of 0.02 mm. At the minimum depth of 0.005 mm, no significant change in phase composition was detected within the experimental error. The increase in monoclinic phase content is accompanied by a decrease in microhardness from 15800 to 14400 MPa. Conclusions. The results demonstrate that grinding depth is a governing technological parameter con-trolling mechanically induced phase transformation and the associated changes in the local mechanical properties of zirconia–alumina composite ceramics</jats:p>