摘要:
在实验室条件下利用五氧化二钒和碳粉制备了碳氮化钒。试验采用六种温度曲线和七种不同的配碳量以确定最佳的反应温度和配碳量。结果表明,采用温度制度5得到的样品中钒含量和氮含量都达到较高的值;随着样品中配碳量的增加,样品中的钒含量略有增加,氮含量略有降低,而残余的碳含量增加。当配碳量为29%和30%时,可获得钒含量为76%,氮含量为18%的碳氮化钒。依据V2O5碳还原和增氮反应机理,整个过程可分为三个阶段:V2O5热分解生成低价VO2阶段、VC (VN)生成阶段和氮化反应渗氮阶段。根据试验结果得到较合适的温度制度为:第一阶段采用较大的升温速度(30℃/min),第二阶段采用较小的升温速度(6.8℃/min),保温温度1 250℃,保温时间为1 h,第三阶段采用降温速度为10℃/min,降到800℃。
关键词:
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碳氮化钒 /
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制备 /
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五氧化二钒 /
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温度 /
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配碳量
Abstract:
Vanadium carbonitride was prepared by vanadium pentoxide and carbon powder in laboratory conditions.Six temperature curves and seven different carbon contents were adopted to determine the optimum reaction temperature and carbon addition.The results show that the content of vanadium and nitrogen in the sample obtained by temperature system 5 are both higher than those of samples by other temperature systems.With the increase of carbon addition,the content of vanadium in the sample increases slightly but the content of nitrogen decreases slightly,and the residual carbon content increases in the sample.When the carbon addition is 29% and 30%,vanadium carbonitride with 76% of V and 18% of N can be obtained.According to the reaction mechanism for carbon reduction of V2O5 and nitrogen addition,the whole process is divided into three stages including VO2 formation through thermal decomposition of V2O5,VC(VN) formation and nitriding,respectively.The more suitable temperature regime was obtained at 30 ℃/min of heating speed in the first stage,6.8 ℃/min of heating speed in the second stage,1 250℃ for 1 h of heat preservation,and 10 ℃/min of cooling rate to 800 ℃ in the third stage.