探索碳膜在不同工况环境中的摩擦学性能

发布时间：2018-02-14 02:40

本文关键词： 金刚石薄膜类金刚石薄膜摩擦学性能特殊环境　出处：《中国地质大学(北京)》2015年硕士论文　论文类型：学位论文

【摘要】：碳膜因其具有高硬度、高耐磨性、低摩擦系数、高电阻率、高热导率、化学惰性、抗腐蚀等优良性能在特种环境中有着广泛的应用。但是碳膜的摩擦学性能受环境影响较大,特殊环境与普通工况下的摩擦学性能有很大差异,不同环境下对性能的要求也不同。本文探究了空间钻探、地球物理勘探和喷丝头冲孔等工况环境下碳膜的摩擦磨损性能。结果表明:(1)采用热丝化学气相沉积法在硬质合金表面沉积金刚石薄膜,测定了薄膜在大气和真空环境中4种不同温度下的摩擦系数。发现在大气环境中,金刚石薄膜的摩擦系数曲线较平稳,摩擦系数值随温度升高而减小,磨损主要与磨屑和氧化膜保护层有关;而在真空环境中,摩擦系数曲线波动剧烈,起初随温度升高而增大,650 oC时减小,磨损主要与转变层及表面裂纹有关。真空环境中磨损比大气环境严重,薄膜失效温度更低。温度升高到650 oC后,两种环境中均出现石墨化现象,导致摩擦系数降低。(2)采用非平衡中频双靶磁控溅射法在Cr12Mo4V钢表面沉积Cr/Cr Nx/CryCz/Cr-DLC多层梯度膜。通过表面形貌观察到在偏压-140 V时,Cr-DLC薄膜表面光滑、结构致密;并且该偏压下薄膜的硬度较高,膜基结合力好,摩擦磨损率最低,性能最佳。大气和海水环境中薄膜的摩擦学性能随偏压的变化变化趋势相似,但大气中薄膜的摩擦系数和磨损率均高于海水中,表明薄膜在海水中的减摩抗磨能力比大气中强。(3)采用热丝化学气相沉积法在高速钢冲针表面沉积金刚石薄膜。直接在高速钢冲针上沉积的金刚石薄膜不完整,存在大量非金刚石相,表面有炭黑聚积成的颗粒。一般基体温度下高速钢冲针可能因为温度过高导致针尖熔化。通过沉积Ti N过渡层可有效消除直接镀膜产生的不利影响,过渡层上沉积的金刚石薄膜均匀完整,无明显缺陷,但金刚石薄膜表面粗糙度大,可通过增大碳源浓度、降低沉积气压等方法降低表面粗糙度。
[Abstract]:Carbon film is widely used in special environment because of its excellent properties such as high hardness, high wear resistance, low friction coefficient, high resistivity, high thermal conductivity, chemical inertia and corrosion resistance. The tribological performance of special environment is very different from that of normal working condition, and the requirement of performance is also different in different environment. The friction and wear properties of carbon film in geophysical exploration and spinneret punching. The results show that the diamond film is deposited on the surface of cemented carbide by hot-filament chemical vapor deposition. The friction coefficient of diamond film was measured at four different temperatures in atmosphere and vacuum environment. It was found that the friction coefficient curve of diamond film was stable and the friction coefficient decreased with the increase of temperature. Wear is mainly related to wear debris and oxide film protective layer, while in vacuum environment, the friction coefficient curve fluctuates sharply, and decreases with the increase of temperature at first, at 650oC. The wear is mainly related to the transition layer and surface cracks. The wear in vacuum environment is more serious than that in atmospheric environment, and the failure temperature of film is lower. When the temperature rises to 650 OC, graphitization occurs in both environments. Cr/Cr Nx/CryCz/Cr-DLC multilayer gradient films were deposited on the surface of Cr12Mo4V steel by unbalanced medium frequency double target magnetron sputtering method. The surface morphology of the films was observed to be smooth and compact at the bias voltage of -140V. The film has high hardness, good adhesion, the lowest friction and wear rate, and the best performance. The variation trend of the tribological properties with bias voltage is similar in atmosphere and seawater environment. However, the friction coefficient and wear rate of the films in the atmosphere are higher than those in seawater. The results show that the antifriction and antiwear ability of the thin film in seawater is stronger than that in atmosphere. The diamond film deposited on the surface of high speed steel punching needle by hot filament chemical vapor deposition method is incomplete, and the diamond film deposited directly on the high speed steel punching needle is incomplete. There are a large number of non-diamond phases on the surface, and there are particles of carbon black accumulation on the surface. In general, the high speed steel punching needle may lead to tip melting due to excessive temperature at substrate temperature. The adverse effect of direct coating can be effectively eliminated by deposition of tin transition layer. The diamond film deposited on the transition layer is uniform and complete without obvious defects, but the surface roughness of the diamond film is large, and the surface roughness can be reduced by increasing the concentration of carbon source and reducing the deposition pressure.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ127.11;TB383.2

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