开放体系下碳热还原氮化法制备Cr_(2)(C,N)粉末

Preparation of Cr_(2)(C,N)powders by carbothermal reduction-nitridation method in open system

开放体系下,采用碳热还原氮化法,以Cr_(2)O_(3)和炭黑为原料,制备了单相Cr2(C,N)粉末。通过TG-DSC、XRD和SEM等测试手段,研究了合成温度、保温时间、氮气流量等工艺参数对制备Cr2(C,N)的影响规律。结果表明,随着合成温度升高,物相演变遵循:Cr_(2)O_(3)→(Cr_(3)O_(3)、Cr_(3)C_(2)和Cr_(6.2)C_(3.5)N_(0.3))→Cr_(2)(C,N)的规律,当合成温度超过1100℃,可获得单相Cr_(2)(C,N);合成温度为1200℃、保温时间为2 h、氮气流量为2.5 L/min时,Cr_(2)(C,N)粉的物相组成、粒径尺寸和氮含量等综合性能最优,制备条件最佳;适当提高合成温度、延长保温时间、增大氮气流量有助于Cr_(2)(C,N)中氮含量的提高。

Single phase Cr_(2)(C,N)powder was prepared by carbothermal reduction nitridation method,with carbon black and chromium oxide as raw materials in an open system.By means of TG-DSC,XRD and SEM,the effects of synthesis parameters,including heating temperature,holding time and nitrogen flow rate on the preparation of Cr_(2)(C,N)were studied.The results show that with the heating temperatures increase,the phase evolution follows the sequences of Cr_(2)O_(3)→(Cr_(3)O_(3),Cr_(3)C_(2)and Cr_(6.2)C_(3.5)N_(0.3))→Cr_(2)(C,N).When temperatures reach 1100℃,the single phase Cr_(2)(C,N)powder can be obtained.The optimal parameters of synthesis Cr_(2)(C,N)powders,with the prefer phase constitution,particle size and nitrogen content,are 1200℃for 2 h under the nitrogen flow rate of 2.5 L/min.It contributes to increasing the nitrogen content of Cr_(2)(C,N),while increase synthesis temperatures,prolong holding time and improve the nitrogen flow rate appropriately.