Abstract The scratching processes of monocrystalline and polycrystalline silicon carbide (SiC) with diamond grit were studied by molecular dynamics simulation to investigate the nanoscale material removal behavior. The results showed that, for both monocrystalline and polycrystalline SiC, the material removal processes were achieved by the phase transition to the amorphous structure. Large depth of cut and low scratching speed induced the large scratching forces, stress, and surface damage layer thickness. Less amorphous structure phase transition, smaller normal scratching force, and higher tangential stress were found in polycrystalline SiC, comparing to the monocrystalline SiC, due to the material soften caused by the microstructure, under all scratching conditions. Furthermore, the tangential stress showed highly dependent on the grain geometry and grain boundary (GB) location in polycrystalline. The subsurface damage layer in polycrystalline was little thinner than that in monocrystalline before the new GB generation at a low depth of cut and deteriorated at large depth of cut. In addition to the plastic deformation, which occurred in the monocrystalline SiC nanoscale scratching, the intergranular fracture and transgranular fracture were also observed through the GB generation and connection in polycrystalline SiC.

中文翻译：

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碳化硅纳米级材料去除行为的分子动力学模拟

摘要 通过分子动力学模拟研究了金刚石磨粒对单晶和多晶碳化硅（SiC）的划痕过程，以研究纳米级材料的去除行为。结果表明，对于单晶和多晶 SiC，材料去除过程都是通过向非晶结构的相变实现的。大切割深度和低刮擦速度导致较大的刮擦力、应力和表面损伤层厚度。与单晶 SiC 相比，由于微观结构导致材料软化，在所有划痕条件下，多晶 SiC 中的非晶结构相变更少，法向划痕力更小，切向应力更高。此外，切向应力高度依赖于多晶中的晶粒几何形状和晶界 (GB) 位置。多晶的亚表面损伤层在低切深处比新一代 GB 之前的单晶薄一点，在大切深处恶化。除了发生在单晶 SiC 纳米级划痕中的塑性变形外，还通过多晶 SiC 的 GB 生成和连接观察到晶间断裂和穿晶断裂。