Preparation And Mechanical Properties Research Of Y-ZrO₂/Al₂O₃ Nanocomposite Ceramic Materials For Pressureless Sintering

Al₂O₃ ceramics are widely used,especially in valves,which make up for the defects of high temperature,wear and corrosion resistance of many metal materials,but their brittleness and fracture toughness limit their excellent performance.The addition of Y-Zr O₂ can effectively reduce the brittleness and increase the fracture toughness of ceramic matrix while maintaining its excellent properties.The main research aim of this paper is to take nanometer Al₂O₃ as ceramic Matrix,and nanometer Y-Zr O₂ as toughening and reinforcing phase.By changing Y-Zr O₂addition volume,forming pressure,sintering temperature,heat preservation time,using normal pressure sintering technology,and controlling related preparation and sintering technology,the Y-Zr O₂/Al₂O₃ nanometer polyceramics with excellent performance are finally obtained.The microstructure of the materials under different preparation conditions was analyzed by X-Ray diffraction,optical microscope and scanning electron microscope.The density,hardness,flexural strength and fracture toughness of the materials were measured.The results showed that:?1?The proper addition of Y-Zr O₂ had the effect of refining grain.The grain sizes of Al₂O₃ and Y-Zr O₂ were about 1.1?m and 600 nm respectively.?2?The addition of Y-Zr O₂ is beneficial to the improvement of the property of the polyphase ceramics.The density can reach 98.58%,The vickers hardness up to 18.95 GPa,flexural strength and fracture toughness can reach 421 MPa and 7.98 MPa·m¹/2/2 respectively.?3?Increasing the forming pressure,properly increasing the sintering temperature and extending the heat preservation time will improve the density of the materials and the internal organization of the materials,and consequently the mechanical properties of the materials.?4?The materials have small inner grain size,uniform distribution of Y-Zr O₂ particles,and more Y-Zr O₂ grains and crystalline particles at the boundary of three or four forked grains,which effectively restrain the crack propagation.?5?There are many toughening mechanisms such as second phase toughening,diffusion toughening,phase transition toughening,intragranular particles toughening and nano toughening,which make the properties of the material improve greatly.