石墨阴极弧增强放电及ta-C涂层沉积研究

发布时间：2018-06-25 04:31

本文选题：ta-C涂层 + 真空阴极电弧离子镀　；参考：《哈尔滨工业大学》2017年硕士论文

【摘要】：ta-C涂层具有许多能和金刚石相媲美的卓越性能,例如良好的化学稳定性、较高的硬度和优异的抗磨损性能,良好的生物力学性能和生物相容性。ta-C涂层与高速钢基体间热膨胀系数相差1个数量级,在高速钢上直接沉积ta-C涂层,硬度和弹性模量以及膨胀系数的巨大差异,会导致涂层与基体界面之间产生很高的内应力,膜基结合强度很差。为了提高ta-C膜层与高速钢基体的膜基结合强度通常在ta-C膜层与基体之间沉积打底层和过渡层,实现硬度、弹性模量和膨胀系数等物理性能的梯度变化。本文通过改变线圈电流、直流电弧电流、工作气压、平均脉冲电流等实验参数研究石墨阴极弧放电特性。本文设计基体/Cr/CrC/ta-C梯度膜层结构来沉积ta-C涂层,利用真空阴极电弧离子镀技术在M2高速钢和单晶Si片上制备了ta-C涂层,并研究了不同参数下涂层组织形貌、相结构的变化及机理以及工艺参数的改变对涂层膜基结合强度、摩擦磨损性能、硬度的影响。放电测试结果表明,工艺参数对石墨阴极弧放电特性有很大影响。基体电流随电弧电流增加而增大,电弧电压几乎保持不变;基体电流随着线圈电流的增加而增大,电弧电压也不断增加;基体电流随着Ar气气压的增大先增大后减小,电弧电压几乎保持不变;基体电流变化波形与脉冲电流波形相似,电弧电压在脉冲部分明显增大。ta-C涂层结构分析表明,沉积时间超过30min时,ta-C涂层开始脱落,ID/IG值随着时间延长不断增大,sp3键含量不断降低。线圈电流增大对试样轰击作用加强,ID/IG值总体趋势增大。ID/IG值随电弧电流增加先减小后增大,60A时sp3键含量最高。ta-C涂层性能分析表明,随时间延长膜基结合强度逐渐下降,50min的涂层表面出现褶皱现象。线圈电流增大,膜基结合强度想降低后升高。电弧电流增大,膜基结合强度下降,但都在HF2级别以上。电流相等时,脉冲电流的膜基结合强度明显低于直流。线圈系列纳米硬度最大的为0.1A,硬度为33.5GPa。脉冲系列纳米硬度最大的为脉冲平均电流80A,硬度为45GPa。硬度和石墨化是影响摩擦系数的两大因素。
[Abstract]:The ta-C coating has many excellent properties comparable to diamond, such as good chemical stability, high hardness and excellent wear resistance. Good biomechanical properties and biocompatibility. The difference of thermal expansion coefficient between ta-C coating and high speed steel substrate is 1 order of magnitude. The difference of hardness, modulus of elasticity and expansion coefficient of ta-C coating deposited directly on high speed steel is great. The interfacial stress between the coating and the substrate is very high, and the bonding strength of the film substrate is very poor. In order to improve the bonding strength between ta-C film and high speed steel substrate, a gradient change of physical properties such as hardness, modulus of elasticity and coefficient of expansion is realized by depositing the bottom layer and transition layer between ta-C film and substrate. The discharge characteristics of graphite cathode arc are studied by changing the experimental parameters such as coil current DC arc current working pressure and average pulse current. In this paper, the substrate / Cr / Cr / C gradient film structure was designed to deposit ta-C coating. Ta-C coating was prepared on M2 high speed steel and single crystal Si substrate by vacuum cathode arc ion plating. The microstructure of the coating was studied under different parameters. The effect of the change of phase structure, mechanism and process parameters on the bonding strength, friction and wear properties and hardness of the coating. The discharge test results show that the process parameters have great influence on the discharge characteristics of graphite cathode arc. The substrate current increases with the increase of the arc current, and the arc voltage increases with the increase of the coil current, and the base current increases with the increase of ar gas pressure, and then decreases with the increase of ar gas pressure. The arc voltage is almost unchanged, the variation waveform of substrate current is similar to that of pulse current, and the arc voltage increases obviously in the pulse part. When the deposition time is longer than 30min, the ID-IG value of the coating begins to fall off, and the content of sp3 bond decreases with the increase of the deposition time. When the coil current increases, the general trend of ID-R / IG value increases. When the arc current increases, the sp3 bond content of the coating decreases first and then increases with the increase of the arc current. The results show that: 1) when the arc current increases, the content of sp3 bond is the highest in the coating. When the bonding strength of the film decreased for 50 min, the surface of the coating was wrinkled. When the coil current increases, the bonding strength of the film base increases after decreasing. When the arc current increases, the bonding strength of the film base decreases, but all of them are above the level of HF2. When the current is equal, the bonding strength of the film base of the pulse current is obviously lower than that of the DC. The maximum hardness of the coil series is 0.1A and the hardness is 33.5 GPA. Pulse series nanocrystalline hardness is the maximum pulse average current 80 A, hardness of 45 GPA. Hardness and graphitization are two main factors affecting friction coefficient.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG174.4

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