真空烧结烧结温度和保温时间对WC-6％Ni细晶硬质合金组织及性能的影响

摘要

WC-6％Ni fine-grained cemented carbide was prepared by spray drying,hydrogen reduction and carbonization and vacuum sintering.The effects of sintering temperature and holding time on the densification,microstructure and properties of WC-6％ Ni fine-grained cemented carbide were discussed.The sample was investigated by SEM,XRD,and vickers hardness method.The results show that the density and hardness of the samples increase significantly with increasing sintering temperature.When the sample is sintered at 1 420 ℃ for an hour,the density of WC-6％Ni cemented carbide is 14.764 g/cm3 and hardness is 1 609 HV.When the sintering temperature is 1 420 ℃,and chang the holding time,then the results changes.If the holding time is short,the dissolution and precipitation behavior goes not enoughly,and a small number of pores are not completely filled by the liquid phase.If the holding time is too long,the element Ni,C and so on will volatile,and form a large number of holes and Ni pools.%本文采用雾化干燥,氢还原碳化法,真空烧结等工艺制备WC-6％Ni细晶硬质合金,主要讨论了不同的烧结温度和保温时间对WC-6％Ni细晶硬质合金致密化,显微组织及性能的影响.采用扫面电镜(SEM),XRD,维氏硬度计等分析设备对样品进行检验.结果表明:随着烧结温度的提高,该样品的密度和硬度显著提高,当真空烧结温度1 420℃,保温1h,WC-6％Ni硬质合金的密度为14.764 g/cm3,硬度1 609 HV.在烧结温度1 420℃条件下,改变保温时间.保温时间过短,溶解和析出进行的不充分,导致少部分孔洞没有被液相完全填充,保温时间过长会导致粘结相Ni、元素C等损失,形成大量孔洞和Ni池等缺陷.