Preparation Of ZrO₂-TiC Nanocomposites Powders And Ceramics And Electrical Performance Study

With the development of high-tech industry,the demand for ceramic materials and performance improvement will become higher and higher.EDM can manufacture highly complex ceramic devices with electrical conductivity above 1 S/cm,which can effectively shorten the processing cycle and reduce production cost.In orde to adopt EDM tech and expand the application field,composite ceramics were usually prepared through the transformation between insulator and conductor by adding conductive phase to the insulating matrix.Therefore,conductive ceramics have become a research hotspot.Starting with the synthesis of powders,the effects of raw material ratio and process parameters on the phase,microstructure and electrical conductivity properties of the resulting ceramic materials were investigated.Herein,ZrO2-TiC powders were synthesized by modified hydrothermal assisted sol-gel method for the first time.Combined with XRD,SEM,TG-DTA and other characterizations,the phase evolution and reaction mechanism were analyzed.The results showed that the freeze-drying is an optimal method.Precursors were calcined at 1300? for 2 h with the Glucose:Ti(OC4H9)4 ratio of 1.3.The resultant ZrO2-TiC powders exhibit high crystallinity,nano-size and uniform morphology(Near spherical).For 5%mol Y2O3 doping to stabilize ZrO2 phase,the overall size of ZrO2-TiC powders increase slightly.Y2O3-stabilized tetragonal ZrO2 polycrystals(Y-TZP)composites with 16-28 vol%TiC were successfully synthesized via modified hydrothermal-assisted sol-gel method.SEM images show that TiC particles distribute homogeneously in the Y-TZP matrix with average grain sizes ofabout 390-670 nm and 150-230 nm for Y-TZP and TiC phases,respectively.Additional TiC fraction has negative effect for relative density and hardness,but significant positive influence on electrical conductivity.The electrical conductivity increases from 115 S/m to 1.23×105 S/m with TiC content ranging from 16 to 28 vol%,manifesting that the percolation threshold is about 16 vol%TiC for this system.It is much lower than those of reported Y-TZP-TiC ceramics.High electrical performance is probably attributed to the high D/d ratio and submicron grain size.