催化超滑:金催化作用下非晶含氢碳薄膜的工程超滑

Catalytic superlubricity: engineering superlubricity caused by the catalytic effect of gold on hydrogenated amorphous carbon structure

摩擦磨损是导致机械系统高能耗和失效的主要原因,降低摩擦系数、减小磨损,特别是实现超滑(超低摩擦,μ<0.01)是解决上述困窘的有效方法.本文针对在工程尺度难以实现超滑应用的技术壁垒,将催化与摩擦学相结合,提出了金催化非晶含氢碳薄膜原位生成石墨烯纳米带实现工程超滑的新方法,即"催化超滑".本文采用等离子体化学气相沉积法(PECVD)和化学溶液镀膜法分别制备了所需非晶含氢碳薄膜和镀金钢球,以非晶含氢碳薄膜/镀金钢球构成滑动摩擦副,并进一步研究了其摩擦学行为.结果表明,与非晶含氢碳薄膜/轴承钢球摩擦副相比,含氢碳薄膜/镀金钢球摩擦副摩擦系数低至0.008,仅是含氢碳薄膜/轴承钢球摩擦副的25%左右;磨损深度仅为含氢碳薄膜/轴承钢球摩擦副的31%左右.这是因为摩擦过程中金在摩擦热和剪切力的作用下,原位催化诱导非晶碳发生向石墨烯的转变,石墨烯有序的结构利于形成非公度接触,可有效减小界面剪切力从而降低摩擦系数."催化超滑"的新方法在宏观尺度上实现了超滑,为解决超滑工程应用难的问题提供了新的思路.

Material and energy losses caused by friction and wear hinder the development of mechanical systems. An effective way to solve the problem is to reduce friction coefficient and wear. Here, we proposed in-situ formation of graphene nanoribbons via gold-catalyzed reconstruction of amorphous hydrogenated carbon matrix to achieve engineering superlubricity. And we called this method "catalytic superlubricity". In detail, amorphous hydrogenated carbon(a-C:H) films were grown by plasma chemical vapor deposition(PECVD), and gold(Au) films on steel balls were obtained by electroless chemical deposition. Comparing study on the tribology properties of the couple pairs of aC:H/Au and a-C:H/GCr15 was carried out via home-made Tribometer 3. The results show that, compared with the couple pairs of a-C:H/GCr15(μ~0.032 and wear depth of 128 nm), the couple pairs of a-C:H/Au show a friction coefficient of 0.008 and wear depth of 40 nm, respectively. The reason of superlubricity of the couple pairs of a-C:H/Au is that, based on the catalysis of gold, the graphene nanoribbons formed in-situ during friction. The ordered structure is conducive to the occurrence of incommensurate contact, and effectively reduces the interfacial shear force and thus lowers the friction coefficient.