Study On Synthesis Of Zr(C,N) Powders

Zirconium nonoxide ceramic with high hardness and melting point, good corrosionand friction resistance and other excellent properties is regarded as a new type ofadvanced material. It can be widely used in hard alloy cutting, electronic productsmanufacturing, special refractory material and other mechanical parts. For thedevelopment of a new type material, the experiment researched on preparing Zr2CN andZrC. It has great theoretical research value, and established the theory and technologyfoundation for Zr2CN and ZrC development and application.In this experiment, monoclinic zirconia m-ZrO2(d50=50nm), partially stabilizedzirconia Ca-PSZ (<74μm) and carbon black (d50=50nm) were selected as raw materials.Thermomechanical analysis, TG-DSC-MS, XRD, SEM and EDS were used to researchthe ZrO2-C-N2high temperature reaction. The effects of mixture composition, synthetictemperature and holding time on Zr2CN and ZrC synthesis were also researched as wellas the formation mechanism. The results showed that ZrO2-C-N2system high temperaturereaction began with C atom spreading into the ZrO2and its stabilization effect. In thetemperature range of1500~1650℃, the eventual reaction product of ZrO2-C-N2wasZr2CN. With the extension of synthesis temperature, holding time and C content, Zr2CNand ZrC content in the composite material was in the rule of statistical increase. Underthe conditions of ZrO2/C mole ratio1:3~1:4, high purity N2atmosphere and1650℃temperature, m-ZrO2and carbon black as raw materials was able to synthesis100%Zr2CN, Ca-PSZ and carbon black could produce97%Zr2CN. The grain size of Zr2CNwas about0.5~3μm. When the ZrO2/C mole ratio was in1:3.5~1:4and under theconditions of high purity Ar atmosphere and1650℃, m-ZrO2, Ca-PSZ and carbon blackas raw materials could create ZrC with purity above95%, and the grain size was about in0.6~2μm. Zr2CN and ZrC formation mainly included four circulating cross stages: solid-gas diffusion and the formation of stable ZrO2stage; the formation of surface Zr2CN orZrC stage; partial decomposition of ZrO2and gas phase sediment formation stage; theformation of inner Zr2CN or ZrC and partial oxidation of surface Zr2CN or ZrC.