Preparation And Application Of ZrC Modified Flake Graphite In Molten Salt Media

Molten salt method is a new powder synthesis method which had the benefits of lowing the reaction temperature,improving the reaction rate and increasing the contact area in system.And zirconium carbide is a superhard material with high chemical stability,good corrosion resistance and high temperature resistance so that it can be used as a material in surface protection and high temperature structural.Taken advantage of flake graphite's difficult to dissolve in most molten salt systems and used template method as th e growth mechanism,C-ZrC composite with ZrC coating layer was synthesized and the action mechanism of reaction temperature,reaction time,molten salt composition and graphite size to phase composition and microstructure were studied.In addition,reaction kinetic model was established based on graphite's stratified structure and the control mechanism of reaction rate was confirmed.In order to confirm the control mechanism of oxidation rate,the diffusion control model of boundary layer in high-temperature oxidation was established and kinetic parameters were calculated further.At last,the influences of different content of C-ZrC on material's antioxidation and slag resistance by bringing C-Zr C composite in Al₂O₃-C refractories were researched.?1?Used molten salt method in argon,ZrC coating layer was successfully synthesized on the surfaces of nature graphite by in-situ reaction in the temperature range of 900 ? to 1200 ? and C-ZrC composite structure was formed between ZrC and graphite.In NaClNa F molten salt media,zirconium could achieve effective transport of mass so that zirconium could react quickly with graphite in molten salt system with template method.By rising reaction temperature,it was further generated to the synthesis of ZrC and the growth of grains.Meanwhile,made external diffusion model eligible by studying the thickness of ZrC coating layer in different reaction time.?2?Used the method of Kissinger to calculate kinetic parameters,whereby,Ek=288k J·mol-1.It could prevent graphite's further oxidation after ZrC coating layer's oxidation on the surface of nature graphite.It was proved that the crossing of O2 from circumstances to boundary layer was the rate control mechanism by oxidation model.?3?When graphite was partial substituted by synthesized C-ZrC composite,Al₂O₃-C refractories performed better antioxidation and slag resistance.Nevertheless,samples' slag resistance reduced when C-ZrC composite was totally used to replace graphite and it presented loose and porous close to the slag in inner materials.