Preparation of Si2N2O/SiC Composite Powders Using Carbothermal Reduction Nitridation Method for Diatomite
Silicon oxynitride(Si2N2O)is a high-performance refractory and high-temperature structural material,which has advantages such as excellent creep resistance,corrosion resistance,and oxidation resistance.In this work,diatomite was used as silicon source,acetylene carbon black was used as reducing agent,and the Si2N2O/SiC composite powders were synthesized in situ on the surface of diatomite through carbothermal reduction nitridation method.The samples were characterized by X-ray diffraction(XRD)analysis,scanning electron microscopy(SEM),and N2 adsorption/desorption isotherms.The results indicate that under the condition of raw materials ratio m(diatomite)∶m(acetylene carbon black)=1∶1,the SiO2 completely transforms into Si2 N2O and β-SiC after calcination at 1 450 ℃ for 4 h,and the sample shows a spherical morphology with mesoporous structure,while a large number of layered small particles distribute around the large particles.As a high-performance high-temperature structural material,Si2N2O/SiC composite powders could be a promising candidate for application in the field of structural composite materials.
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