Cobalt Layer Formation:New Insights and In Situ Observations

摘要：

　　The formation of a surface layer of cobalt binder during sintering of cemented carbides is widely known and has been thoroughly discussed in literature.The phenomenon occurs upon cooling,however the details of the mechanism are still uncertain.To further investigate the mechanism,different cooling experiments and atmospheres were combined with in situ observations of sample surfaces during cooling,acquiring new data about the timescale and temperature range in which the formation of the layer takes place.Based on these results,the authors propose a new mechanism for the cobalt layer formation.After an initial transport of liquid cobalt towards the surface,caused by the slightly decarburizing conditions during vacuum sintering,the high surface tension of liquid cobalt governs the formation of the layer.If the formation of a cobalt surface layer is provoked,this implies limits for the achievable layer thickness and also confirms known measures to prevent the cobalt layer formation.Fast cooling or cooling under carburizing conditions can prevent the cobalt layer formation.In situ observation of the cobalt layer formation above 1300 ℃.Observation of the timespan and temperature interval the cobalt layer formation takes place.Study of the effects of different cooling rates and different sintering atmospheres on cobalt layer formation.Proposal of a new mechanism for the cobalt layer formation.

关键词： cobalt layer formation cobalt capping cemented carbides liquid phase migration

作者: E.Sachet W.D.Schubert Georg Mtihlbauer J.Yukimua Y.Kubo

作者单位: Institute of Chemical Technologies and Analytics,Vienna University of Technology,Austria Hitachi Tool Engineering,Ltd.,Japan

会议类型: 国际会议

会议名称: 2012 Zhuzhou International Conference on Cemented Carbides(株洲硬质合金国际学术会议)

会议地点: 株洲

会议语种:英文

页码: 184-200

在线出版日期: 2012-09-12（万方平台首次上网日期，不代表论文的发表时间）