Frictional and Protective Characteristics of Hard Amorphous Carbon Film Deposited by High-velocity Impact of Carbon-black Particles

1. 在<10^6> V/m量级的均匀电场中，通过静电加速超细碳黑颗粒达到高速，使其在真空中与冷阴极（衬底）机械碰撞，可以以数百< 100> /min的沉积速率非热制备硬质非晶碳膜。认为石墨炭黑是在高功率密度冲击下沉积的，其结构发生了非晶相变化，包括碳原子的过量4倍键和悬垂键。这可以从薄膜的半导电阻率及其温度依赖性、退火弛豫行为和中等硬度等特性中得到证明。为了摩擦学应用的目的，在不同的大气和摩擦条件下，用球盘滑动摩擦试验研究了薄膜的摩擦和磨损机制，通过给球样品一个接触点重复描述同一轨迹的方式进行更多的定位运动。，得到如下结果：(1)在正常湿润气氛下，摩擦系数<mu>随滑动次数的增加呈指数递减。这种行为被认为服从边界润滑机制，其中<mu>取决于物理吸附水蒸气的覆盖率，估计吸附热约为36 kJ/mol。(2)与类金刚石碳膜相似，在大量载玻片上呈现出<mu>约0.02的优异低值。这种最佳润滑意味着吸收物的摩擦脱附与低覆盖状态下的吸附达到平衡。(3)在相对恶劣的条件下，如低湿度、高速、高负载滑动，优越的摩擦解吸带来平衡状态的打破。然后，随着轻度磨损的发生，<mu>从最优值逐渐增大。(4)这些结果表明，水蒸气不仅对膜的基本润滑效率起抑制作用，而且由于吸附会终止膜表面的活性黏结键而对磨损产生抑制作用。少

1. A hard amorphous carbon film can be unthermally prepared at deposition rate of several handred <ang> /min by electrostatically accelerating ultra-fine carbon-black particles to high velocity in a uniform electric field of the order of <10^6> V/m, by making the energetic particles mechanically collide with cold cathode (substrate) in vacuo.2. It is considered that graphitic carbon-black is deposited with the structural change in an amorphous phase including excessive 4-fold and dangling bonds of carbon atoms due to high power density impact. This can be proved from the film characteristics such as the semi- conductive resistivity and its temperature dependence, their relaxation behaviour in annealing and the moderately high hardness.3. For the purpose of tribological application, the frictional and the wear occurring mechanisms of the film are investigated under various atmospheric and frictional conditions with a ball-on-disk sliding friction test, by giving the ball sample a recipr … More ocating motion in the manner that the contact point describes a same locus repeatedly. And, the following results are obtained;(1) It is found in normal humid atmosphere that the coefficient <mu> of friction decreases exponentially as the number of slides increases. This behaviour is considered to obey the boundary lubrication mechanism in which the <mu> depends on the coverage ratio of physisorbed water vapour as estimated the adsorption heat of about 36 kJ/mol.(2) Excellent low values of <mu> of about 0.02 are presented at large number of slides as similar to diamond-like carbon films. This optimum lubrication means that the frictional desorption of the absorbate reaches in equilibrium with the adsorption at a low coverage state.(3) In relatively severe condition such as low humidity, high speed and high load slidings, superior frictional desorption brings the break of the equilibrium state. Then, the <mu> increases gradually from the optimum value as a mild wear occurs.(4) These results suggest that water vapour acts as an inhibitor not only to the essential lubrication efficiency of this film, but to the wear occurring as the adsorption will terminate active dungling bonds at film surface. Less