摘要
基于第一性原理分别计算了WC-Co/Graphite/Diamond、WC-Co/Si CC-Si/Diamond和WC-Co/Si CSi-C/Diamond界面模型的粘附功、断裂韧性,分析了电子结构和态密度。结果表明:Graphite/Diamond界面粘附功极小,金刚石在石墨基面上成核不良;WC-Co/Graphite界面处Co与C(Graphite)原子具有同种电荷而相斥,添加Si C中间层改变了界面处原子的电荷分配与成键方式,WC-Co/Si C界面Co与C(或Si)原子具有异种电荷而相吸,且Co-Si(Si C)键强于Co-C(Si C)键;Si C/Diamond界面C(Si C)-C(Diamond)键强于Si(Si C)-C(Diamond)键。因此,三种界面模型中各界面的粘附功Si CSi-C/Diamond>Si CC-Si/Diamond>WC-Co/Si CSi-C>WC-Co/Si CC-Si>WC-Co/Graphite>Graphite/Diamond。总之,添加Si C中间层提高了金刚石涂层硬质合金刀具膜基界面结合性能。
Based on the first-principles,the adhesion work and fracture toughness of WC-Co/Graphite/Diamond,WC-Co/Si CC-Si/Diamond and WC-Co/Si CSi-C/Diamond interface models were calculated. The electronic structures and densities of states of the models are further analyzed. The results show that the adhesion work of Graphite/Diamond interface is very small,and the nucleation of diamond on the graphite surface is poor. At the WC-Co/Graphite interface,Co and C( Graphite) atoms have the same charges and are repulsive. The addition of the Si C interlayer changes the charge distribution and bonding style of atoms at the interface. Co and C( or Si) atoms at the WC-Co/Si C interface have different charges and attract each other,and the Co-Si( Si C) bond is stronger than that of Co-C( Si C). At the Si C/Diamond interface,C( Si C)-C( Diamond) bond is stronger than that of Si( Si C)-C( Diamond).Therefore,the interface adhesion works in the three interface models are: Si CSi-C/Diamond > Si CC-Si/Diamond > WC-Co/Si CSi-C> WC-Co/Si CC-Si> WC-Co/Graphite > Graphite/Diamond. In short, the addition of Si C interlayer improves the bonding properties of film-substrate interface of the diamond coated carbide tools.
引文
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