硬质合金刀具表面过渡层的制备及其性能

Preparation and properties of surface transition layer for cemented carbide tool

采用双辉等离子表面冶金技术在硬质合金铣刀片表面制备了SiC/HfC过渡层,研究了基材温度对过渡层物相、表面和截面显微形貌、显微硬度和结合强度的影响。结果表明,不同基材温度下SiC/HfC过渡层都由WC、Si、SiC、HfC和CoHf相组成;随着基材温度的升高,HfC垂直于(111)晶面的平均晶粒尺寸逐渐增大,过渡层表面粗糙度呈现先减小而后增大,HfC内层厚度和生长速率逐渐增加,而SiC外层厚度和生长速率先增加而后减小;随着基材温度的升高,过渡层表面硬度呈现先增加而后减小的趋势,在基材温度为800℃时取得最大值(2920HV0.1),此时过渡层的结合强度为HF1~HF2级(涂层结合力好),过渡层发生剥落的临界载荷为77N,为适宜的制备SiC/HfC过渡层的基材温度。

SiC/HfC double-layer transition layer was prepared on the surface of carbide milling insert by double glow plasma surface metallurgy technology,the effect of substrate temperature on the phase,surface and sectional morphology,microhardness and bonding strength of the transition layer was studied.The results show that the SiC/HfC transition layer is composed of WC,Si,SiC,HfC and CoHf phases at different substrate temperatures;with the increase of substrate temperature,the average grain size of HfC perpendicular to(111)crystal plane increases gradually;with the increase of substrate temperature,the surface roughness of the transition layer first decreases and then increases,the inner thickness and growth rate of HfC increase gradually,while the outer thickness and growth rate of Si C increase first and then decrease.The surface hardness of the transition layer increases first and then decreases with the increase of substrate temperature,and the maximum value(2920 HV0.1)of the transition layer is obtained when the substrate temperature is 800℃,at this time,the bonding strength of the transition layer is HF1-HF2(good bonding force of the coating),and the critical load of spalling of the transition layer is77 N,which is the suitable substrate temperature for preparing the Si C/Hf C transition layer.