Preparation Technics And Mechanism Of Chromium Carbide Nanopowders Produced By Calcium Chromium Oxide Mesophase Carbon Thermal Reduction Method

Chromium carbide?Cr₃C₂?has high melting point,high hardness,good wearing-resistance,corrosion-resistance and oxidation-resistance.Thus,it is now wildly applied in cemented carbides,steels,electronic,aerospace field.The carbon thermal method was used to synthesize Cr₃C₂ nanopowders.The products were characterized by TG-DSC,XRD,SEM and TEM.This paper mainly studied the preparation technology,properties,preparation mechanism and refining mechanism of Cr₃C₂ powders.The study of calcium chromium oxide preparation show that the powders with the single phase of CaCr₂O₄ can be synthesized under the addition that Ca/Cr?the mol ratio of Ca and Cr?is 1:1,there is Cr₂O₃ in the product when Ca/Cr is lower than 1:1.The powders with the single phase of CaCr₂O₄ can be synthesized under the additions of Ca/Cr 1:1,1000 oC,180 min are mainly composed of spheroidal particles,with a particle size between 0.5² ?m.The study of chromium carbide nanopowders preparation show that the carbon content increases with the increase of carbon ratio?the mol ratio of C and Cr?.The combined carbon content reach to the maximum value,the free carbon content is 0.07 wt.% when C/Cr is 2.60:1,the free carbon content rapid growth when C/Cr is bigger than 2.60:1.The powders with the single phase of Cr₃C₂ can be synthesized under the additions of C/Cr 2.60:1,1000 oC,60 min.display good dispersion and are mainly composed of spheroidal particles,with a particle size around 51.5 nm,and show no obvious agglomerating phenomenon.