Study On Interface Bonding Properties Of Diamond Coated Carbide Tools

Diamond coated carbide tools not only exhibit high hardness and wear resistance of diamond,but also exhibit good impact resistance and toughness of cemented carbide.They are ideal tools for processing aluminum alloy,fiber or ceramic composite materials.The interface bonding properties of the tools has a significant impact on its application.At present,study on diamond coated carbide tools at home and abroad mainly through macroscopic experimental methods,and little study on the interfacial bonding properties from the microscopic atomic scale.Based on molecular dynamics and first-principles,the interface bonding properties were simulated from the microscopic atomic scale.This study has important theoretical and practical significance for revealing the interface bonding mechanism of the coated tools,optimizing its interface structure and coating preparation process.Firstly,the effect of Co content on the interface bonding properties of diamond coated carbide tools was studied.The WC-Co/Diamond interface models with Co content of 6,8,10,and 12wt%were constructed for molecular dynamics simulation.The interface adhesion works and the bond length distribution at the interface were calculated and analyzed.The analysis results show that WC-6wt%Co/Diamond has the highest interface adhesion work and the best interface bonding properties.As the Co content increases,the interface bonding properties is worse.Then,the effect of the interlayer on the interface bonding properties of the diamond coated carbide tools was studied.The WC-Co/interlayer/Diamond interface model with WC-Co cemented carbide with a Co content of 6wt%as the substrate was constructed,and the interlayer is Graphite and TiC,TiN,CrN,SiC,respectively.The interface models were geometrically optimized.The interface adhesion works and fracture toughness were calculated.The electronic structure and density of states were analyzed.The results show that in the WC-Co/Graphite/Diamond interface model,there is no bond formation at the Graphite/Diamond interface.At the WC-Co/Graphite interface,the atoms have the same charge and repel each other,and the cracks are likely to occur in the graphite phase.The addition of TiC,TiN,CrN,and SiC interlayer changes the charge distribution and bonding mode of atoms at the interface,and the atoms at the interface have different charges and attract each other.Therefore,the TiC,TiN,CrN,and SiC interlayer can effectively prevent the diffusion of Co,thereby improving the interface bonding properties of the diamond coated carbide tools,and the SiC interlayer has the best improvement effect,among which the WC-Co/SiCSi-C/Diamond interface structure is the most stable.When TiC,TiN,CrN,and SiC interlayer are added,the cracks are most likely to occur at the TiCTi/Diamond interface,TiNTi/Diamond interface,WC-Co/CrNcr interface,and WC-Co/SiCC-Si interface,respectively.Finally,the effect of deposition temperature on the interface bonding properties of SiC.interlayer diamond coated carbide tools was studied.The WC-6wt%Co/SiCSi-C/Diamond and WC-12wt%Co/SiCSi-C/Diamond interface models were constructed and molecular dynamics simulations were carried out at different deposition temperatures(T=973,1023,1073,1123,1173,1223,1273K).The interface adhesion works and the bond length distribution at the interface were calculated and analyzed.The analysis results show that for WC-Co cemented carbide substrate with 6wt%Co content,when SiC interlayer is deposited on WC-Co cemented carbide substrate at 1123K,and then diamond coating is deposited on WC-Co/SiC at 1173K,the interface bonding properties of SiC interlayer diamond coated carbide tools are the strongest.For WC-Co cemented carbide substrate with 12wt%Co content,when SiC interlayer is deposited on WC-Co cemented carbide substrate at 1073K,and then diamond coating is deposited on WC-Co/SiC at 1223K,the interface bonding properties of SiC interlayer diamond coated carbide tool was the strongest.