Experimental Research on One-Step Preparation of Ultrafine Niobium Carbide by Low-Temperature Carbothermal Synthesis Process
In order to solve the problems of poor product quality,long reaction time and high energy con-sumption in the one-step carbonization production process of niobium carbide,Nb(OH)5 with relatively well controlled particle size was selected as the experimented raw material,carbon black was used as the re-ducing agent,and after ball minning and mixing,nano niobium carbide with high purity was directly pre-pared by one-step carbonization method.The effects of carbon fitting ratio(mass ratio of Nb(OH)5 to car-bon black),ball milling time,reduction temperature and reduction time on the phase composition and mi-crostructure of NbC product were analyzed by XRD and SEM.The experimental results show that when the carbon fitting ratio is too high,the carbon black hinders the thermal decomposition of Nb(OH)5,which leads to insufficient reduction.With the extension of ball milling time of the raw material,the increase of carbonization temperature and the extension of the reduction time,the purity of NbC product increases firstly and then tends to be stable.In view of energy saving and nanomaterial preparation,the optimized process parameters are as follows:carbon fitting ratio of 1∶0.3,ball milling time of 1 h,reduction tempe-rature of 1 300℃ ,and reduction time of 3 h.Under the optimized experimental conditions,the purity of the obtained NbC product reaches 98.9%,and the particle size is less than 200 nm.
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