Research On Fracture Mode And Fracture Toughness Of Typical Engineering Ceramics

Typical engineering ceramic materials not only have high strength and hardness,but also have excellent heat resistance,thermal expansion and low thermal conductivity and high resistance to oxygen,that have been widely used in engines,chemical equipment,cutting tool blade materials,and aerospace engineering.However,the basic problem is crack which should be carefully considered in the design and use of engineering ceramics.Combine with the study of crack morphology and fracture mechanism of some typical engineering ceramic materials,analyzed ceramics toughen mechanism,tested and calculated the fracture toughness of ceramic materials by indentation method.A quantitative method to determine the toughening effect of crack deflection was proposed.In recent years,research on the form of ceramic fracture showed improve the creep resistance and anti fatigue performance,can make ceramic materials more widely used.The normal temperature fracture morphology and fracture mechanism of hot press sintering Al₂O₃ ceramic,ZrO₂ ceramic,Al₂O₃/ZrO₂ ceramic,Al₂O₃/ZrO₂ ceramic and Si₃N₄based composite ceramics were analyzed.Analysis of high temperature fracture of Al₂O₃/ZrO₂ multiphase ceramics and Si₃N₄/Si₂N₂O composite ceramics in high temperature tensile forming process.analysis of high temperature fracture mechanism,and explord the superplastic deformation mechanism of nano ceramics.Use Marc software to establish the finite element model of crack propagation in fracture process of ceramic materials,analyze the influence of bridging,pull-out,deflection and gradient composite on crack propagation.The fracture toughness of Si₃N₄/Si₂N₂O and Al₂O₃/ZrO₂ composite ceramics was measured by indentation method,based on the original formula of Pasteur crack,proposed a quantitative formula for judging the effect of crack deflection.Analyze the crack deflection in the fracture process of toughen effect and quantitative calculation.