Research On Al₂O₃-based Ceramic Tool Materials Toughened By In-situ Synthesized Whiskers

Al2O3-based ceramic tool materials have the advantages of high temperature resistance,wear resistance,corrosion resistance and high hardness.However,the disadvantages of low toughness and high brittleness greatly limit their application in broader areas.Whisker toughened Al2O3-based ceramic tool materials have high fracture toughness and high temperature mechanical properties.In addition,the preparation method of ceramic tools with whiskers has the disadvantages of complex dispersion process.Therefore,in this paper,whisker toughened Al2O3 based ceramic tool materials were developed by in-situ synthesis of whiskers.According to the physical and chemical compatibility principles of whisker toughened ceramic tool material design,TiC whiskers were selected as the toughening phase of Al2O3-based ceramic tool materials.Through the research and analysis of the growth mechanism of TiC whiskers,it is established that the growth mechanism of TiC whiskers synthesized in-situ in this paper is the solid-liquid-liquid-solid(SLLS)growth mechanism.After studying the growth of synthetic whiskers at different ball milling times,the optimal ball milling time in this paper was determined to be 24 hours.Through the selection and optimization of raw materials for tool preparation,?-Al2O3 doped with 5wt%?-Al2O3 was established as the matrix materials of ceramic tools,TiO2 and industrial carbon black were the main raw materials for in-situ synthesis of TiC whiskers,NaCl and particle size Ni of 30?m was used as the halogenating agent and catalyst for the carbothermal reduction reaction of TiC whiskers synthesized in-situ.The preparation process of TiC whiskers synthesized in-situ was optimized and the best preparation process in this paper was determined by heating 40 minutes to 1500? for 60 minutes and then 10 minutes to 1680? for 30 minutes.After studying the in-situ synthesis of whisker toughened Al2O3-based ceramic cutting tool materials preparation process,the experimental plan of cutting tool materials preparation was determined.The sintering process of the tool materials was optimized by studying and analyzing the mechanical properties and microstructure of the tool materials under different sintering processes.Studies have shown that the in-situ synthetic whisker toughened Al2O3-based ceramic cutting tool materials has the best comprehensive mechanical properties,the bending strength,fracture toughness,and Vickers hardness are 756 MPa,7.46MPa·m1/2 and 19.45 GPa,when the sintering temperature is 1700?,the holding time is 30min and the sintering pressure is 32MPa.The toughening mechanism of in-situ synthesized whisker toughening Al2O3-based ceramic tool materials was studied and the factors affecting the whisker toughening mechanism were analyzed.