几种碳源对碳热还原氮化法制备Ti(C,N)粉末的影响

Influence of several carbon source on Ti(C,N)powders prepared by carbothermal reduction and nitridation method

以纳米TiO2和不同碳源为原料,采用碳热还原氮化法,制备了Ti(C,N)粉末。通过X射线衍射分析、热分析、扫描电镜、化学成分分析等手段研究了TiO2碳热还原氮化过程的反应机理和不同碳源对制备碳氮化钛粉末的影响。结果表明,在TiO2碳热还原氮化过程中,前期主要为TiO2/C固-固反应,后期CO参与的气-固反应变为主要反应;当碳黑为碳源时,比之活性碳和石墨,反应最为完全,而且粉末产物粒度较为细小均匀;同时随着碳黑比表面积的增大,碳氮比随之降低,游离碳和氧含量随之减小;当以比表面积为600m2/g的碳黑为碳源时,配碳量为28.8%的混合物在加热到1700℃,保温3h,氮气流量为1000mL/min的条件下,得到了游离碳含量<0.2%、氧含量<0.5%,总碳为11.42%的碳氮化钛粉末。

Ti（C,N）powders can be prepared by carbothermal reduction and nitridation method with the nanometer TiO2 and different carbon source as starting materials.X-ray diffractometer,TG/DSC thermal analyzer,SEM and chemical analysis are applied to investigate the reaction mechanism on carbothermal reduction-nitridation of TiO2 and the effects of different cardon source on preparation of titanium carbonitride powders.The results show that,in the reaction process,the predominant reaction mechanism is TiO2/C solid-solid reaction in the beginning and subsequent the gas-solid reaction in which CO participates.The reaction of mixtures with carbon black as the carbon source is more complete than those with active carbon and graphite,and the former is finer than the latter two in the grains of reaction products.At the same time,with the specific surface area of carbon black increasing,the carbon/nitrogen ratio declines,and the free carbon content and oxygen content decrease.Moreover,if the mixtures with carbon black specific surface of 600m2/g as the carbon source and a carbon content of 28.8% were isothermal treated for 3h at 1700℃ in an atmosphere of nitrogen flow at 1000mL/min,TiCN powders with free carbon content 0.2%,oxygen content0.5%,and total carbon content =11.42% can be synthesized.