17:10 〜 17:30
[16F-T15-04] Evaluation of Bonding Strength between WC Grains in WC-Co and WC-VC-Co Cemented Carbides
キーワード：cemented carbide, fine-grained WC-Co, bonding strength
Cemented carbides are widely used in cutting tool due to excellent mechanical properties, where the fine-grained WC-Co in combination with VC has high hardness and strength. VC is known as a grain growth inhibitor, however its effect to microscopic mechanical properties, especially WC-WC bonding strength, is still unclear. Here we investigated WC-WC interfacial structure and strength for WC-Co and WC-VC-Co. Micro-cantilevers including WC-WC interface were made by mechanical polishing and FIB. The bending tests were performed by nanoindentation technique to achieve WC-WC interfacial bonding strength.The results showed that WC-VC-Co carbides are lower strength than WC-Co. TEM observations indicated the segregation of V on WC surface in WC-VC-Co. The V-based thin layer reduces the strength between WC grains, which causes poor mechanical properties to induce WC particle dropout. Appropriate control of VC amount and size is crucial parameter to achieve good mechanical properties for fine-grained cemented carbides.