Study On Properties Of Carbon Fiber Reinforced Al₂O₃ Ceramic Matrix Composites

Ceramic materials are widely used in human history,only for daily use and architecture.Since modern times,the rapid development of technology in the fields of electronic information,nuclear industry,aerospace and armor protection has put forward higher requirements for ceramic materials.The special crystal structure of alumina(Al₂O₃)ceramics endows it with excellent physical and chemical properties,but its brittleness limits its popularization and application.In this paper,Al₂O₃ceramic matrix composites are reinforced by carbon fiber cloth and ZrC.It is proposed to lay carbon fiber cloth and Al₂O₃-ZrC composite powder in layers,install mold and press to prepare ceramic blank(powder method for short);After Al₂O₃-ZrC composite powder was pre filled into carbon fiber cloth,ceramic blank is prepared by slurry infiltration and drying(slurry method for short).C_f/Al₂O₃-ZrC matrix composites are prepared by SPS techniques.This paper mainly studies the effects of process on the mechanical properties of C_f/Al₂O₃-ZrC matrix composites,selects the best process,observes its microstructure and studies the toughening mechanism.Based on the design principle of particle dispersion strengthening and fiber strengthening,Al₂O₃ceramic matrix composites are designed to be synergistically toughened by ZrC particles and carbon fibers.Based on elastic mechanics and thermodynamics,the physical and chemical compatibility between ZrC particles and Al₂O₃matrix is analyzed,and it is found that the limit content of ZrC particles in Al₂O₃matrix is 81.95v.%.Reasonable control of the sintering temperature,ZrC particle size and other process parameters can achieve the toughening effect,and the physical compatibility between the two is good;at 25?1727?in between,the ZrC particles and the Al₂O₃matrix do not chemically react.The effects of sintering temperature,ZrC content,carbon fiber cloth layers and applied pressure on the mechanical properties of C_f/Al₂O₃-ZrC matrix composites prepared by powder method are studied by orthogonal test.According to the comprehensive balance method,the process parameters of the C_f/Al₂O₃-ZrC matrix composite with the best comprehensive properties are obtained as follows:the sintering temperature is 1600?,the ZrC content is25wt.%,the number of carbon fiber cloth layers is 3,and the applied pressure is 30MPa.The Vickers hardness,bending strength and fracture toughness of the material prepared on this process parameter are 17.71GPa,743.73MPa and 5.46MPa·m^1/2respectively.The observation of microstructure shows that the main mode of material fracture is intergranular fracture,and there are a few transgranular fractures.The effects of ZrC content,sintering temperature,applied pressure and holding time on the mechanical properties of C_f/Al₂O₃-ZrC matrix composites prepared by slurry method are studied by single factor experiment.When the sintering temperature is 1600?,the ZrC content is 25wt.%,the applied pressure is 50MPa and the holding time is 10min,the bending strength of the material is the highest,which is 739.21MPa;Keeping the sintering temperature,the ZrC content and the applied pressure unchanged and prolonging the holding time to 20min,the fracture toughness and Vickers hardness of the material reach the maximum,which are7.46MPa·m^1/2and 18.15GPa respectively.By observing and studying the fracture morphology,shows that the increase of sintering temperature,ZrC content and applied pressure is conducive to refine the grain,increase the transgranular fracture mode and improve the mechanical properties of the material.