Rejhon Martin, Dědič Václav, Shestopalov Mykhailo, Kunc Jan, Riedo Elisa
Charles University, Faculty of Mathematics and Physics, Institute of Physics, Ke Karlovu 5, CZ-121 16 Prague 2, Czech Republic.
Tandon School of Engineering, New York University, Brooklyn, NY, 11201, USA.
Nanoscale. 2024 Jun 6;16(22):10590-10596. doi: 10.1039/d3nr06281c.
Silicon carbide has excellent mechanical properties such as high hardness and strength, but its applications for body armor and protective coating solutions are limited by its poor toughness. It has been demonstrated that epitaxial graphene-coated SiC can enhance SiC mechanical properties due to the pressure-activated phase transition into a sp diamond structure. Here, we show that atomically thin graphene coatings increase the hardness of SiC even for indentation depths of ∼10 μm. Very importantly, the graphene coating also causes an increase of the fracture toughness by 11% compared to bare SiC, which is in contradiction with the general indirect variation of hardness and fracture toughness. This is explained in terms of the presence of a diamond phase under the indenter while the rest of the coating remains in the ultra-tough graphene phase. This study opens new venues for understanding hardness and toughness in metastable systems and for the applications of graphene-coatings.
碳化硅具有诸如高硬度和高强度等优异的机械性能，但其在防弹衣和防护涂层解决方案中的应用受到其较差韧性的限制。已证明外延石墨烯包覆的碳化硅可由于压力激活的相变转变为sp金刚石结构而增强碳化硅的机械性能。在此，我们表明即使对于约10μm的压痕深度，原子级薄的石墨烯涂层也能提高碳化硅的硬度。非常重要的是，与裸碳化硅相比，石墨烯涂层还使断裂韧性提高了11%，这与硬度和断裂韧性通常的间接变化相矛盾。这是根据压头下方存在金刚石相而涂层的其余部分保持在超韧性石墨烯相来解释的。这项研究为理解亚稳系统中的硬度和韧性以及石墨烯涂层的应用开辟了新途径。
