基片偏压对磁控溅射制备TiB_2涂层结构及性能的影响

Influence of Bias Voltage on Microstructure and Properties of Magnetron Sputtering TiB_2 Coating

为了提高TiB2涂层的致密性,采用磁控溅射技术,通过改变基片偏压,获得了floating,-30V,-90V三种偏压状态的涂层。利用XRD,SEM、纳米压痕仪、Vickers显微硬度仪和摩擦磨损试验机对涂层的结构和性能进行了分析。结果表明:所有制备涂层只存在六方结构TiB2相,偏压为floating状态时制备的涂层表现出疏松的柱状生长结构,硬度为15GPa。随偏压增大,涂层柱状结构变致密甚至消失,硬度和耐磨损性能都得到提高。偏压-30V提高到-90V,相对于floating状态制备的涂层,晶粒尺寸增加了一倍,达到21nm;柱状结构变致密最终消除;硬度从35.5GPa提高到61.9GPa,实现了超硬;同时耐磨损性能提高,使用摩擦副为直径6mm的Al2O3球进行干摩擦实验时,-90V制备的涂层磨损率为5.6×10-16m3/Nm,相对于-30V涂层降低了一个数量级。

In order to improve the compactness of TiB2 coating, the samples with different substrate bias （floating, -30V and -90V） have been deposited by non-reactively magnetron sputtering. The microstrueture was analyzed by X-ray diffraction （XRD） and scanning electron microscope （ SEM）. The nanoindentation, Vickers indentation and wear tests were used to characterize the mechanical proper- ties. The results show that only hexagonal TiB2 crystalline can be identified from all of the coatings. The hardness of coating under floating is lower （-15GPa） with loose columnar structure. With the increase of bias voltage, the columnar structures are found to be compact and even disappear, and the hardness and tear-resistant property of which enhance. When the bias voltage increases from - 30V to - 90V, the size of crystal grain grows by one time to 21nm with the improvement of hardness from 35.5GPa to 61.9GPa. The columnar structure becomes compact and finally disappears. Simultaneously, the wear rate is reduced to 5.6 × 10-16 m3/Nm, when the coating is subjected to the sliding test against A12O3 ball, one order of magnitude lower than that of the coating deposited at - 30V bias.