碳靶电流对掺铬类石墨镀层结构和性能的影响研究

目的采用物理气相沉积磁控溅射方法,通过控制碳靶电流改变掺铬类石墨镀层的碳含量,在高速钢基体上制备不同厚度的掺铬类石墨镀层,以探究碳含量对掺铬类石墨镀层结构和性能的影响。方法采用压痕法和划痕法对镀层的膜基结合强度进行评价。采用维氏显微硬度计对镀层的硬度进行分析。采用ST-2258A四探针测试仪测量镀层的电导率。使用扫描电子显微镜对镀层的微观结构进行分析。使用摩擦磨损仪对镀层的摩擦学性能进行探究。结果随着碳靶电流的增加,掺铬类石墨镀层的截面柱状化现象越来越明显,表面团簇颗粒直径越来越大。碳靶电流为1 A时,镀层的截面形貌为细晶团簇结构;碳靶电流为3 A时,镀层截面产生柱状结构。镀层的复合硬度随着镀层碳靶电流的增加逐渐增大,在碳靶电流为3 A时,镀层的维氏硬度最大,为436HV。随着碳靶电流增加,镀层电导率逐渐上升。结论随着碳靶电流的增大,镀层致密度逐渐下降,镀层的电导率逐渐增加,镀层的摩擦系数逐渐减小,适当的碳靶电流能使类石墨镀层在功能化与力学性能上达到最佳效果。

Effect of Carbon Target Current on Structure and Performance of Chromium-based GLC Coatings

The work aims to prepare chromium-based GLC coatings of different thickness through changing carbon content of the coatings by controlling carbon target current in the method of physical vapor deposition magnetron sputtering method, so as to further explore effects of carbon content on structure and performance of chromium-based graphite coatings. Bonding strength of the film-substrate was evaluated in indentation and scratching methods. Hardness of the coatings was analyzed using Vickers microhardness tester. Electrical conductivity of the coatings was measured using a ST-2258A four-point probe tester. Microstructure of the coatings was analyzed using a scanning electron microscope (SEM). Tribological properties of the coatings were investigated using a friction and wear tester. With the increase of carbon target current, cross-sectional stylolitization of the coating was more obvious and diameter of surface cluster particles increased. When the carbon target current was 1 A, cross-sectional morphology of the coatings was fine-grain cluster structure. When the carbon target current was 3 A, a columnar structure was present on cross section of the coatings. Composite hardness of the coating increased as the carbon target current increased. When the carbon target current was 3 A, microhardness of the coating was the maximum, i.e., 436HV. With the increase of carbon target current, electrical conductivity of the coatings gradually increased. As the carbon target current increases, coating density and friction coefficient decrease gradually while electrical conductivity of the coating increases gradually. Proper carbon target current can achieve optimum efficiency in functional and mechanical properties of graphite coatings.