Study On Preparation And Properties Of ZrO₂ Matrix Composite Ceramics Based On In Situ Reaction Of Cr₂AlC

ZrO₂ceramics have many advantages such as high hardness,good wear resistance,high temperature resistance,corrosion resistance,low density,and rich raw material reserves.They have an important position in the field of structural ceramics and functional ceramics,but their intrinsic brittleness has led to their application.Greatly restricted.Therefore,it is of great significance to find a suitable method to strengthen and toughen ZrO₂ceramics.In this paper,the precursor Cr₂AlC material is prefabricated.The precursor Cr₂AlC and ZrO₂ceramic substrate are mixed and then sintered by microwave.During the sintering process,the precursor Cr₂AlC undergoes in-situ decomposition reaction in the ZrO₂matrix,resulting in the decomposition of Cr₇C₃,Cr₅Al₈,Al₂O₃The product composite synergistically strengthens and toughens ZrO₂ceramics to prepare a ZrO₂based composite ceramic with excellent compre-hensive properties.In this experiment,Cr powder,Al powder,C powder and Cr₃C₂powder,Al powder and Cr powder were used to synthesize the precursor Cr₂AlC.The purity of the synthesized product was analyzed by X-ray diffractometer,scanning electron microscope and other equipment,and the influence of sintering process and raw material type on the purity of the synthesized product was discussed.Using the prepared precursor Cr₂AlC added to the ZrO₂matrix,through the in-situ reaction of microwave sintering,Cr₇C₃,Cr₅Al₈,Al₂O₃and other phases were generated to prepare（Cr₇C₃,Cr₅Al₈,Al₂O₃）/ZrO₂based composite ceramics.Through the physical phase analysis,microstructure analysis,fracture morphology analysis of the composite ceramics,combined with the relative density,microhardness,flexural strength,fracture toughness and other performance tests of the composite ceramics,the amount of Cr₂AlC precursor and the microwave sintering process were explored The effect on ZrO₂-based composite ceramics and the mechanism of strengthening and toughening were discussed.Finally,the differences between in situ generation of composite ceramics and direct doping composite ceramics are discussed.Experimental results Surface:Cr₃C₂powder,Al powder,and Cr powder as raw materials can produce high-purity single-phase Cr₂AlC material under the microwave sintering process at a sintering temperature of 1300℃and a holding time of 20minutes.Its purity reached 94%,which is consistent with the Precursor requirements.After adding the precursor Cr₂AlC to the ZrO₂matrix,after microwave sintering,the Cr₇C₃,Cr₅Al₈,Al₂O₃and other phase grains generated by the in-situ reaction of the precursor Cr2AlC can be dispersed and distributed in the ZrO₂matrix with a good relationship with the matrix phase interface.The addition of Cr₂AlC in the current driver is 15 vol.%,Sintering in microwave process at 1500℃,and holding for 30minutes,the prepared（Cr₇C₃,Cr₅Al₈,Al₂O₃）/ZrO₂-based composite ceramic has better comprehensive performance,relative density is 98.4%,micro hardness It is 14.81 GPa,flexural strength is 811.62MPa,fracture toughness is 14.35MPa·m^1/2,and ZrO2matrix grains are uniform and fine.Compared with pure 3Y-TZP ceramics,all aspects of performance have been improved.The experimental results of（Cr₇C₃,Cr₅Al₈,Al₂O₃）/ZrO₂-based composite ceramics prepared by in-situ reaction formation method and direct doping method are compared.The results show that the second phase particles of ZrO₂-based composite ceramic prepared by direct doping method have obvious agglomeration in the matrix In the process of cooling,ZrO₂undergoes a phase change,and more m-ZrO₂phases are produced.The relative density,microhardness,flexural strength,and fracture toughness are lower than the ZrO₂based composite ceramics prepared by the in-situ generation method.The strengthening and toughening mechanism of ZrO₂-based composite ceramics is mainly the fine-grain strengthening,dispersion strengthening,Cr₇C₃particle pull-out toughening and phase transformation toughening of Al₂O₃ and Cr₇C₃ in the second phase.