功率对YT刀具激光熔覆TiB2/TiN涂层耐磨性的影响

Effect of Power on Wear Resistance of TiB2/TiN Coating on YT Tool Steel

为了提高YT刀具钢的耐磨性能,选择激光熔覆技术在其表面制备TiB_(2)/TiN涂层,并通过试验测试手段研究功率参数对微观组织及耐磨性的影响。研究结果表明,制得TiB_(2)/TiN涂层涂层形成了致密结构,涂层跟基体间达到了紧密结合状态。逐渐增大功率后,涂层厚度也随之提高,在涂层表面区域形成许多小尺寸凸起结构,观察到明显的边界层。TiB_(2)/TiN涂层沉积速率随功率提高呈现线性增长,从2.63 nm/min增大到6.64 nm/min,涂层硬度持续升高。h-BN组织和纳米晶TiB_(2)间共同构成了纳米复合结构,晶界处形成了较高内聚能,获得明显的晶界强化效果。提高功率后,TiB_(2)/TiN涂层摩擦因数先增大后降低,涂层磨损率先升高再下降。功率为2.0 kW时,涂层获得了最大摩擦因数0.79和最大磨损率4.75×10^(-6)mm^(3)(N·mm)。该研究对提高YT刀具的耐磨性能和使用寿命具有很好的理论指导意义。

To improve the wear resistance of YT tool steel,TiB_(2)/TiN coating was prepared by laser cladding on its surface,and the influences of power parameters on microstructure and wear resistance were studied by experimental tests.Results show that the TiB_(2)/TiN coating forms a compact structure which means the coating is closely bonded with the substrate.As the power increases gradually,the coating thickness also increases.Many small convex structures are formed on the coating surface area,and boundary layer is clearly observed.The deposition rate of TiB_(2)/TiN coating increases linearly with the increase of power,from 2.63 nm/min to 6.64 nm/min,and the hardness of the coating continues to increase.The nanocomposite structure is formed between the h-BN structure and nanocrystalline TiB_(2).Higher cohesion energy is formed at the grain boundary,which improves the strengthening effect of grain boundary significantly.As the power is increased,both the friction coefficient and wear rate of TiB_(2)/TiN coating increases first and then decreases.When the power is 2.0 kW,the friction coefficient rises to 0.79 that results in maximum wear rate of 4.75×10^(-6)mm^(3)/(N·mm).This study has a significant theoretical guidence for improving the wear resistance and service life of YT tools.