Study On The Preparation And Properties Of Diamond Cutting Tools For Cemented Carbide Machining

PCD cutting tools,with its superior properties,have shown unparalleled advantages over other cutting tools in many machining fields and gained wider attentions.In this study,PCD cutting tools were prepared using HPHT method.The effect of binding materials and content as well as sintering temperature on the properties of PCD cutting tools,such as phase composition,microstructure,density and flexural strength,were studied.In Si-Ti-B and Si-Ni-Al bonded PCD cutting tools,the main phase is diamond and the minor phase is SiC.SiC is resulted from the reaction between Si and diamond during HPHT sintering process,which can form diamond-SiC-diamond bonds leading to strong bonding structure.In Co-Al-B bonded PCD cutting tools,the main phase is diamond,while the minor phase is CoAl.Co doesn't react with diamond but form CoAl alloy which serves as binders.The relative density of PCD cutting tools generally grows with increasing binder contents and sintering temperature.With insufficient binders,pores between diamond particles can't be well filled,which leads to a loose structure.With increasing binder contents,binders fill pores and coat diamond particles leading to higher density.Si-Ti-B bonded PCDs all reached above 91%theory density(TD).The PCD sintered at 1400~oC with 16 wt%binders reached 99.5%TD.Si-Ni-Al bonded PCDs reached over 89%TD and the highest is 99%TD,while lower than Si-Ti-B bonded PCDs on the whole.Co-Al-B bonded PCDs have a lower density and the highest is only 94.8%TD.The flexural strength of Si-Ti-B bonded PCDs first increases then decreases with both increasing sintering temperature and binder contents.The PCD with 16 wt%binders sintered at 1400~oC reached a highest value of 580 MPa.The flexural strength of Si-Ni-Al bonded PCDs increases with increasing temperature,while first increases then decreases with increasing binder content.The highest value of 520 MPa belongs to the PCD with 14 wt%binders sintered at 1500 ~oC.The flexural strength of Co-Al-B bonded PCDs also first increases then decreases with increasing binder content and has a highest value of 320 MPa.On the whole,the flexural strength of Si-Ti-B bonded PCDs is the highest with Si-Ni-Al bonded PCDs ranks second and Co-Al-B bonded PCDs is the lowest.PCDs showed good thermal stability.The Si-Ti-B bonded PCDs have a thermal stable temperature 400 ~oC higher than raw diamond powders.