OBRABOTKAMETALLOV MATERIAL SCIENCE Том 23 № 3 2021 EQUIPMEN . INSTRUM TS Vol. 7 No. 2 2025 Ta b l e 1 Chemical composition of TZ-3Y20AB ceramic powder Mass fraction of chemical compounds, % Y2O3 Al2O3 SiO2 Fe2O3 Na2O ZrO2 3.9±0.3 19±1 <0.02 <0.01 <0.04 balance Ta b l e 2 Physical and mechanical properties of sintered Y-TZP-Al2O3 ceramic Density ρ (g/cm3) Grain diameter dg (μm) Bending strength (MPa) Microhardness HV10 (GPa) Fracture toughness K1c (MPa·m1/2) 5.5±0.2 0.4±0.09 1200±160 14±0.6 7.2±0.4 The elemental composition of the initial ceramic powder is given in Table 1. The measurements showed that the actual particle size of the ceramic powder was in the range of 0.04 –0.09 μm and the specific surface area was 15 ± 3 m2/g. The results of measurements of physical and mechanical properties carried out on representative specimens are presented in Table 2. The phase composition of the ground surface of the sintered Y-TZP-Al2O3 ceramics is shown in Fig. 4. It can be seen that the main phases are the matrix phase of tetragonal ZrO2 and the strengthening phase of α-Al2O3. A small amount of monoclinic ZrO2 (≈3 vol.%) could appear due to grinding of the surface of the ceramic inserts, when a phase transition from the metastable tetragonal to the stable monoclinic phase occurs under load. The results of observations of the process of dry turning with ceramic cutting inserts are presented and described below. The modes were varied according to the data specified in Table 3. It was noted that, regardless of feed rate and cutting depth, at a cutting speed of 200 m/min, a spiral chip with traces of whiteness is formed with periodic appearance of burning chips, and in the speed range from 300 to 400 m/min, the chip consists of individual fragments, the intensive combustion of which during cutting is accompanied by a sheaf of sparks (Fig. 5). Let us consider in detail the wear characteristics of the working surfaces that form the cutting edges of ceramic inserts. Characteristic patterns of wear and destruction of the working surfaces of the cutting edges are shown in Fig. 6. Fig. 4. X-ray diffraction pattern of Y-TZP-Al2O3 composite ceramic
RkJQdWJsaXNoZXIy MTk0ODM1