镍在WC合成中加速效应的机理

Study on Accelerating Mechanism of Nickel during Synthesis of Tungsten Carbide

本文以钨-碳体系为研究出发点,高能球磨钨、活性炭和镍的混合粉末,应用XRD、SEM、化学分析等手段,对反应产物进行分析。结果发现当镍含量为5%,球料比为50:1(体积比)时,球磨50h即可合成WC,或者当镍含量为5%,球料比为30:1(体积比)时,球磨100h也可合成WC,而没有镍参与的情况下,当球料比为30:1(体积比),球磨50h后,仍有大量未反应的钨和碳存在,这说明在机械合金化合成WC的过程中,镍能有效的缩短反应时间,提高反应速率,原因是在镍的周围形成了以镍为中心的微聚团,增大了钨和碳的接触几率和接触面积,缩短了扩散距离,从而缩短了反应时间。

The mixed powder of W, active carbon and Ni is ball milled and the resultants are analyzed by means of XRD, SEM and chemical analysis. The results show that WC can be synthesized under the condition of the content of Ni is 5%, the volume ratio of ball and material is 50：1 after 50 hours milling, or under the condition of the content of Ni is 5%, the volume ratio of ball and material is 30：1 after 100 hours milling, while there will be plenty of unreacted W and C left even after 50 hours millLug in case of absence of Ni,indicating that Ni can shorten synthesis time of WC, increase reaction velocity. This may be attributed to plenty of Ni centric micro-gathering agglomerates which increase the contact probability and area of W and C, shorten the diffusion distance and the reaction time.