METHOD OF PRODUCING TWO-LAYER COMPOSITE CERAMICS BASED ON ZIRCONIUM DIOXIDE, HAVING PLASTICITY MARGIN AND HIGH VALUES OF HARDNESS AND WEAR RESISTANCE Russian patent published in 2024 - IPC C04B35/488 B82Y40/00 B32B18/00 

FIELD: ceramics.

SUBSTANCE: invention relates to methods of producing high-strength and wear-resistant composite ceramics based on zirconium dioxide, stabilized in a tetragonal phase, having plasticity margin at room temperature and high resistance to low-temperature degradation. Invention can be used in the manufacture of articles for structural and medical purposes, subject to mechanical and tribological loads, including in a humid atmosphere (cutting tools, spinnerets, drawing dies, bearings, implants). To obtain two-layer composite ceramics, two powder mixtures are prepared with weight ratios: 1) ZrO₂:CaO:Al₂O₃=92.1:2.9:5; 2) ZrO₂:CaO:Al₂O₃:SiO₂=90.17:2.85:4.9:2.08. Mixtures are successively subjected to liquid grinding in a planetary mill and shrinkage in a furnace at temperature of 80 °C. Then the mixtures are laid in the mould so that the thickness of the layer which does not contain SiO₂ (mixture No. 1) does not exceed 10% of the thickness of the second layer (mixture No. 2) and after sintering does not exceed 200 mcm, and is subjected to uniaxial pressing at pressure of 500 MPa. Sintering is carried out in a two-step mode: for 5 minutes at temperature of 1,300 °C, then for 4 hours at temperature of 1,200 °C. In the obtained two-layer composite ceramics there are no layering cracks, in both layers more than 90% of zirconium dioxide is in the tetragonal phase, aluminium oxide crystallites are uniformly distributed throughout the volume of the matrix material, the average size of the ZrO₂ and Al₂O₃ crystallites does not exceed 150 nm and 200 nm, respectively.

EFFECT: increased ultimate compression strength (up to 2.27±0.05 GPa) and provision of plasticity margin (not less than 0.16% of inelastic deformation) at room temperature with preservation of high values of hardness 12.75±0.25 GPa and low wear intensity values 4.16×10^-7±0.23×10^-7 mm³/H×m of surface layer.

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