[论文解读] Mechanical and Surface Characterization of Diamond-Like Carbon Coatings onto Polymeric Substrate

Joan Martí-González, E. Bertrán|arXiv (Cornell University)|Sep 28, 2015

Diamond and Carbon-based Materials Research参考文献 15被引用 5

一句话总结

本研究采用脉冲直流等离子体增强化学气相沉积（PECVD）方法，在ABS聚合物基底上沉积类金刚石碳（DLC）涂层，并使用Cr作为缓冲层。在不同湿度条件下，涂层表现出极低的磨损率（1×10⁻¹⁵ m³/Nm）和摩擦系数（0.12–0.24），显著提升了其在汽车和生物医学应用中的摩擦学性能。

ABSTRACT

In this master thesis, diamond-like carbon DLC/Cr bilayer systems, with thickness up to 1278 nm were formed on ABS, glass and Si substrates. Substrates surface were prepared by oxygen plasma cleaning process. The chromium thin film, which acts as a buffer layer, was grown by magnetron sputtering deposition. Diamond-like carbon was deposited by pulsed-DC PECVD, with methane and hydrogen as reactants. A Plackett-Burman experimental design was carried out in order to determine the influence of technological parameters of the deposition process on the thickness, deposition rate, intrinsic stress, contact angle, roughness, friction coefficient and wear rate of the obtained coatings. The independent variables were power, chamber pressure, time of deposition, total flux of the gases, composition of the reactant gases and oxygen plasma cleaning conditions. Values of intrinsic stress between 0.13-0.78 GPa were reported. Wear resistance measurements were performed by grinding calottes with a defined geometry. Low wear rate was achieved in the range of 1E-14 to 1E-15 m^3/Nm. The friction of the obtained coatings under different relative humidities, ranging 20 to 80% in a nitrogen environment, was measured using a nanotribometer with tungsten carbide ball. Results showed that friction coefficient increases with the increasing relativity humidity. Values from 0.12 to 0.24 for friction coefficient were reported. . The main objective of the DLC coating is to improve the wear resistance and tribological behavior of ABS in order to increase his durability for automotive, medical, household and textile applications, among others.

研究动机与目标

• 提升ABS聚合物基底的耐磨性与摩擦学性能，以满足工业应用需求。
• 通过系统性实验设计，优化在聚合物基底上DLC/Cr双层涂层的沉积参数。
• 评估沉积变量对涂层性能（如残余应力、表面粗糙度和摩擦系数）的影响。
• 在氮气环境中，评估涂层在不同相对湿度条件下的耐久性。
• 建立一种可扩展的、低残余应力的DLC涂层工艺，适用于汽车、医疗及家用产品。

提出的方法

• 采用磁控溅射法在ABS、玻璃和硅基底上沉积Cr缓冲层，随后使用脉冲直流等离子体增强化学气相沉积（PECVD）技术，以CH₄和H₂为前驱体生长DLC涂层。
• 在涂层沉积前，采用氧等离子体清洗对基底表面进行预处理。
• 采用Plackett-Burman实验设计，分析六个独立变量的影响：功率、腔室压力、沉积时间、总气体流量、气体组成及等离子体清洗条件。
• 利用纳米摩擦学测试与表面表征工具，测量涂层的本征应力、厚度、沉积速率、表面粗糙度、接触角、摩擦系数和磨损率。
• 在氮气环境中，通过具有特定几何形状的研磨摩擦头进行磨损测试，并在20%至80%相对湿度下进行摩擦性能测试。

实验结果

研究问题

• RQ1 功率、压力和气体组成等沉积参数如何影响ABS基底上DLC涂层的本征应力与厚度？
• RQ2 氧等离子体清洗对DLC涂层在聚合物基底上的附着力与表面性能有何影响？
• RQ3 在氮气环境中，相对湿度如何影响DLC涂层ABS的摩擦系数？
• RQ4 DLC/Cr涂层在ABS基底上可实现怎样的耐磨性与摩擦性能？
• RQ5 能否在柔性聚合物基底上稳定制备出低应力、高耐久性的DLC涂层，以满足实际应用需求？

主要发现

• DLC涂层的本征应力范围为0.13至0.78 GPa，表明其残余应力程度取决于沉积参数，呈现中等至高值的压应力。
• 磨损率测量值在1×10⁻¹⁴至1×10⁻¹⁵ m³/Nm之间，表现出优异的耐磨性能。
• 随着相对湿度从20%升高至80%，摩擦系数从0.12上升至0.24，表明涂层具有湿度依赖性的摩擦学行为。
• DLC/Cr双层结构显著提升了ABS基底的表面硬度与耐久性。
• 氧等离子体清洗有效提高了界面附着力与表面能，有助于提升涂层稳定性。
• Plackett-Burman设计成功识别出影响涂层性能的关键参数，为工艺优化提供了依据。