Synthesis of nanosized tungsten carbide powder by a new carburizer
This paper deals with the production of nanosized tungsten carbide (WC) powders from a new carburizer. Acetylene and absolute ethyl alcohol used as carburizer were investigated.The results show that acetylene was not the appropriate carburizer for nanosized WO3 powders for its relative high carbon content. WO3 can be carburized completely by alcohol/H2 which takes effect in the reduction and carburization by the resultants of its decomposition, CH4, CO, C and H2. The partial pressure of inner atmosphere determines the rate of carburization very much. Tungsten carbide powder, which mean size characterized by Small angle X-ray scattering (SAXS) is 74.4nm, is completely carbonized at 880℃ for 80 min under the alcohol vapor flowing rate of 100ml/min. The carbon content of WC was higher than stoichiometric because of the excessive free carbon which was the resultant decomposed by alcohol and methane at high temperature. WC formation depends on concentration gradient of atmosphere containing carbon and a diffusion process, occurring by the diffusion of carbon into W. Since free carbon was formed at the surface of carbide. Kinetics analysis is essential to determine which the major factor.
nanosized tungsten carbide acetylene absolute ethyl alcohol mechanism
刘祥庆 林涛 罗骥 郭志猛
北京科技大学 材料科学与工程学院,北京100083
国际会议
成都
英文
2007-11-19（万方平台首次上网日期，不代表论文的发表时间）