Department of Materials Science and Engineering, Centennial Campus North Carolina State University, Raleigh, NC 27695-7907, United States of America.
Nanotechnology. 2018 Nov 9;29(45):45LT02. doi: 10.1088/1361-6528/aadd75. Epub 2018 Aug 29.
Q-carbon is a metastable phase of carbon formed by melting and subsequently quenching amorphous carbon films by a nanosecond laser in a super undercooled state. As Q-carbon is a material harder than diamond, it makes an excellent reinforcing component inside the softer matrix of a composite coating. In this report, we present a single-step strategy to fabricate adherent coatings of hard and lubricating Q-carbon nanocomposites. These nanocomposites consist of densely-packed sp -rich Q-carbon (82% sp ), and sp -rich α-carbon (40% sp ) amorphous phases. The nanoindentation tests show that the Q-carbon nanocomposites exhibit a hardness of 67 GPa (Young's modulus ∼ 840 GPa) in contrast to the soft α-carbon (hardness ∼ 18 GPa). The high hardness of Q-carbon nanocomposites results in 0.16 energy dispersion coefficient, in comparison with 0.74 for α-carbon. The soft α-carbon phase provides lubrication, resulting in low friction and wear coefficients of 0.09 and 1 × 10, respectively, against the diamond tip. The nanoscale dispersion of hard Q-carbon and soft α-carbon phases in the Q-carbon nanocomposites enhances the toughness of the coatings. We present detailed structure-property correlations to understand enhancement in the mechanical properties of Q-carbon nanocomposites. This work provides insights into the characteristics of Q-carbon nanocomposites and advances carbon-based superhard materials for longer lasting protective coatings and related applications.
Q-碳是一种由非晶碳薄膜在纳秒激光超深过冷状态下熔化和随后淬火形成的亚稳碳相。由于 Q-碳是一种比金刚石还硬的材料，因此它是复合涂层软基质内部的优秀增强组件。在本报告中，我们提出了一种单步策略来制造坚硬且润滑的 Q-碳纳米复合材料附着涂层。这些纳米复合材料由富 sp 的致密 Q-碳（82% sp ）和富 sp 的α-碳（40% sp ）非晶相组成。纳米压痕测试表明，Q-碳纳米复合材料的硬度为 67 GPa（杨氏模量约为 840 GPa），而软α-碳的硬度约为 18 GPa。Q-碳纳米复合材料的高硬度导致其能量分散系数为 0.16，而α-碳的能量分散系数为 0.74。软的α-碳相提供了润滑作用，导致与金刚石尖端相比，摩擦和磨损系数分别低至 0.09 和 1×10。硬 Q-碳和软α-碳相在 Q-碳纳米复合材料中的纳米分散增强了涂层的韧性。我们提出了详细的结构-性能相关性，以了解 Q-碳纳米复合材料机械性能的增强。这项工作提供了对 Q-碳纳米复合材料特性的深入了解，并推进了基于碳的超硬材料在更持久的防护涂层和相关应用中的发展。
