划痕法表征TD处理制备的VC涂层界面结合强度

 为了测定碳化钒(VC)涂层与基体之间的结合强度,分析涂层与基体的结合机制,采用热扩散(TD)处理在冷作模具钢Cr12MoV表面制备了VC涂层,通过扫描电镜(SEM)观察了其表面与界面形貌,利用能谱议(EDS)分析了结合界面的V、C元素的分布,用划痕法测定了涂层与基体的界面结合强度,并对涂层失效机理进行了分析.结果表明,经TD处理制备的VC涂层与基体结合界面为成分梯度界面,二者结合面为成分含量呈梯度变化的过渡层,V元素含量从表面到基体逐渐下降,而C元素含量逐渐上升;其结合界面处化学元素相互结合,形成冶金结合,测得涂层与基体的结合强度平均值为45.7 N;涂层失效形式为界面层的压裂,其结合强度主要与VC涂层残余压应力有关.

Token of Interfacial Bonding Strength for VC Coating Prepared by TD Process with Scratching

In order to measure bonding strength of vanadium carbide(VC)coating and substrate and analyze combination mechanism,VC coating is prepared on the surface of cold worked die steel Cr12MoV with thermal diffusion(TD) process.The surface and interfacial morphologies,interfacial element distribution of elements V and C and the bonding strength are analyzed respectively with observation by scanning electron microscope(SEM),energy dispersive spectrometer(EDS) and scratch test,and the failure mechanism of VC coating is discussed.The experimental results show that the bonding interface of the VC coating-substrate prepared by the TD process is an element grad,bonded with the change of element grad in the transition layer in which the V content decreases gradually from its surface to the substrate while the C content increases gradually.Chemical elements are combined mutually in the bonding interface,which forms a metallurgical combination.The average value of interfacial bonding strength is 45.7 N measured with a scratch test.The coating failure with the scratch test is an interfacial fracturing,and the bonding strength of the VC coating depends mainly on its compressive residual stress.