Matrix Influence On The Organization And Performance Of Coated Cemented Carbide

The coated cemented carbide indexable inserts are used more and more widely. The different application requires the coated cemented carbides with corresponding property. High performance coated cemented carbide should be based on special cemented carbide substrate.Four cemented carbide WC-Co,WC-(W,Ti)C-(Ta,Nb)C-6%Co, WC-(W,Ti)C-(Ta,Nb)C-10%Co, WC-(W,Ti)C-(Ta,Nb)C-TiCN-Co have been processed and investigated as the substrates for coating. By conventional inspection, microscope, SEM, the effect of carbon content and sintering atmosphere as well as TiCN content on the properties and interface structure of the coated cemented carbide substrate were studied. The cutting performance of coated cemented carbides were examined by metal cutting test.WC-(W,Ti)C-(Ta,Nb)C-TiCN-Co alloy as substrate has excellent properties with higher TRS than alloys of WC-Co, WC-(W,Ti) C-(Ta,Nb)- 6%Co, with the same hardness as WC-(W,Ti)C-(Ta,Nb)C -6%Coo There are enriched cobalt layer in the surface of WC-(W,Ti) C-(Ta,Nb)C-TiCN-Co alloy , which is beneficial to coating as substrate.TRS and hardness of cemented carbide as substrate decrease with the increase of alloy carbon content which depends on the initial carbon content and sintering atmosphere. Sintering in Argon results in formation of (W,Ti) C and (Ta,Nb) C in alloys of WC-(W,Ti) C-(Ta,Nb)-6%Co and WC-(W,Ti)C-(Ta,Nb)C-10%Co, and cobalt segregation on the surface of alloys.After coated, TRS of the cemented carbide deteriorates obviously, N-phase appears in the interface between substrate and coat in the case of the low carbon content.The cutting experioments show that the coated WC-Co is suitable for cutting cast iron, the coated WC-TiC-(Ta, Nb)C-6%Co suitable for steel, the coated WC-(W,Ti) C-(Ta,Nb) C-TiCN-Co with high strength edge is the best. The WC-TiC-(Ta,Nb)C -10%Co can not be used as substrate.