Department of Mechanical Engineering, National Institute of Technology Silchar, Assam- 788 010, India.
Department of Mechanical Engineering, National Institute of Technology Silchar, Assam- 788 010, India.
J Mech Behav Biomed Mater. 2021 Jun;118:104478. doi: 10.1016/j.jmbbm.2021.104478. Epub 2021 Mar 20.
Ag-doped Cr/DLC coatings were deposited on medical grade 316 LVM stainless steel using DC magnetron sputtering. Morphological study of the coating indicated the formation of island of Ag clusters owing to the inability of Ag to form carbides, which is also corroborated from the XRD analysis. The composite coating showcased elastic nature suggestive from the p-h curve obtained from the nanoindentation test. However, the coating possesses 33% ductility, which is an important virtue for stress relieving attributed to Ag in the carbon matrix. The coating registered improved adhesion due to CrC carbide formation in the interlayer. The composite coating was subjected to lubricated sliding in physiological fluid against carbon fiber reinforced PEEK (CFRPEEK) friction pair to realize a closer scenario to hip implant articulation. A lubricious film of Ag with scattered particles of PEEK was formed in the sliding interface resulting in a long run-in process during sliding. The composite coating suffered mild wear on the Ag-doped DLC top layer with few gullies of wear scar deep into the interlayer due to graphitization of carbon in the film. A statistically significant difference was observed in the hardness, H/E, elastic work, and plastic work; however, there was no statistically significant difference in H/E attribute between the unworn and worn surface. What is more, Raman spectra of the worn (I/I = 1.9 ± 0.2) and unworn surface (I/I = 2.1 ± 0.1) were indicative of no significant loss in the structural integrity of the composite coating.
采用直流磁控溅射法在医用级 316LVM 不锈钢上沉积了掺银的 Cr/DLC 涂层。涂层的形貌研究表明，由于 Ag 不能形成碳化物，因此形成了 Ag 团簇的岛屿，这也得到了 XRD 分析的证实。从纳米压痕试验获得的 p-h 曲线可以看出，复合涂层表现出弹性特性。然而，该涂层具有 33%的延展性，这是由于 Ag 在碳基质中缓解应力的一个重要优点。由于中间层形成了 CrC 碳化物，涂层的附着力得到了提高。复合涂层在生理流体中与碳纤维增强聚醚醚酮（CFRPEEK）摩擦副进行了润滑滑动，以实现更接近髋关节植入物关节的情况。在滑动界面形成了一层含有分散的 PEEK 颗粒的润滑 Ag 膜，导致在滑动过程中经历了一个较长的磨合过程。复合涂层的 Ag 掺杂 DLC 顶层受到轻度磨损，由于薄膜中的碳发生石墨化，在中间层深处出现了几个磨损痕迹的凹痕。在硬度、H/E、弹性功和塑性功方面观察到了显著的差异；然而，在未磨损和磨损表面之间，H/E 属性没有统计学上的显著差异。此外，磨损（I/I = 1.9 ± 0.2）和未磨损表面（I/I = 2.1 ± 0.1）的拉曼光谱表明，复合涂层的结构完整性没有明显损失。
