Ghajari Fatemeh, Vandadi Mobin, Asumadu Tabiri Kwayie, Klenam Desmond, Soboyejo Winston, Rahbar Nima
Department of Civil, Environmental and Architectural Engineering, Worcester Polytechnic Institute, Worcester, Massachusetts 01609-2280, United States.
College of Engineering, State University of New York (SUNY) Polytechnic Institute, Utica, New York 13502, United States.
Langmuir. 2025 Aug 19;41(32):21425-21434. doi: 10.1021/acs.langmuir.5c01902. Epub 2025 Aug 8.
This study explored a sustainable method for depositing carbon-based coatings on Ni-Invar and Ti-6Al-4V metallic substrates using a pack carburization process with cyanide-rich (cassava) leaves as the carbon source. Comprehensive experimental and computational analyses were performed to investigate the composition, structure, and tribological performance of the coatings. Characterization using X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, scanning electron microscopy (SEM), and lateral force microscopy (LFM) revealed that the Ni-Invar substrate developed turbostratic multilayer graphene coatings with minimal carbide formation, achieving ultralow coefficient of friction (COF) values of 0.08 (macroscale) and 0.0033 (nanoscale). In contrast, Ti-6Al-4V substrates formed coatings rich in titanium carbide and metal carbonates with more disordered carbon structures, resulting in higher COF values of 0.1 and 0.0147, respectively. Monte Carlo simulations illustrated an island growth mechanism on Ni-Invar driven by dominant carbon-carbon interactions, while Ti-6Al-4V exhibited uniform layer growth due to stronger carbon-substrate affinity. Density Functional Theory (DFT) calculations provided further insight, showing that Ti had a strong affinity for graphene, with a binding energy of -1.1440 × 10 eV, whereas Ni and Fe exhibited stronger self-affinity (-1.6250 × 10 and -1.7190 × 10 eV, respectively), favoring metal-metal bonding over carbon-metal bonding. These integrated experimental and numerical analyses offer detailed insights into carbon coating structures and their growth mechanisms. The results underscore the critical role of substrate chemistry in determining coating morphology and tribological behavior, highlighting Ni-Invar as a promising candidate for achieving superlubricity through carbon-based surface engineering.
本研究探索了一种可持续的方法，即使用富含氰化物的（木薯）叶片作为碳源，通过包渗碳工艺在镍殷钢和Ti-6Al-4V金属基体上沉积碳基涂层。进行了全面的实验和计算分析，以研究涂层的成分、结构和摩擦学性能。使用X射线光电子能谱（XPS）、拉曼光谱、扫描电子显微镜（SEM）和侧向力显微镜（LFM）进行表征，结果表明，镍殷钢基体形成了具有最小碳化物形成的涡轮层状多层石墨烯涂层，在宏观尺度上实现了0.08的超低摩擦系数（COF）值，在纳米尺度上实现了0.0033的超低摩擦系数值。相比之下，Ti-6Al-4V基体形成了富含碳化钛和金属碳酸盐的涂层，碳结构更无序，导致COF值分别更高，为0.1和0.0147。蒙特卡罗模拟表明，在镍殷钢上由主要的碳-碳相互作用驱动的岛状生长机制，而Ti-6Al-4V由于更强的碳-基体亲和力而表现出均匀的层生长。密度泛函理论（DFT）计算提供了进一步的见解，表明Ti对石墨烯具有很强的亲和力，结合能为-1.1440×10 eV，而Ni和Fe表现出更强的自亲和力（分别为-1.6250×10和-1.7190×10 eV），有利于金属-金属键合而非碳-金属键合。这些综合的实验和数值分析为碳涂层结构及其生长机制提供了详细的见解。结果强调了基体化学在决定涂层形态和摩擦学行为方面的关键作用，突出了镍殷钢作为通过碳基表面工程实现超润滑的有前途候选材料。
