The collision of two cylindrical hydrogen-free diamond-like carbon (DLC) asperities with approximately 60 % sp³ hybridization has been studied using classical molecular dynamics. The severity of the collision can be controlled by the impact parameter b that measures the width of the projected overlap of the two cylinders. For a cylinder radius of R = 23 nm, three collisions with b = 0.5 nm, b = 1 nm and b = 2.0 nm are compared. While for the two small b a single shear band between the collision partners and a strongly localized sp²/sp¹ hybridised third-body zone between the asperities is observed, the b = 2 nm collision is accompanied by pronounced plastic deformation in both asperities that destabilize the metastable sp³-rich phase leading to a drastic increase in the amount of rehybridized tribomaterial. In addition, pronounced roughening of the cylinder surfaces, asymmetric material transfer and the generation of wear debris are found in this case. For the b = 0.5 and 1 nm collision, the evolution of third-body volume can be quantitatively described by a simple geometric overlap model that assumes a sliding-induced phase transformation localized between both asperities. For b = 2 nm, this model underestimates the third-body volume by more than 150 % indicating that plasticity has to be taken into account in simple geometric models of severe DLC/DLC asperity collisions.

中文翻译：

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无氢类金刚石碳原子碰撞中碰撞诱导的第三体形成的分子动力学模拟。

使用经典的分子动力学研究了两个圆柱形无氢类金刚石碳（DLC）粗糙与大约60％sp ³杂交的碰撞。碰撞的严重程度可以通过冲击参数b来控制，该参数测量两个气缸的投影重叠部分的宽度。对于R  = 23 nm的圆柱半径，比较了b  = 0.5 nm，b  = 1 nm和b  = 2.0 nm的三个碰撞。虽然对于两个小b，在碰撞伙伴之间有一个单一剪切带，并且在粗糙之间观察到了强烈定位的sp ² / sp ¹杂化第三体区域，但是b  = 2 nm碰撞在两个凹凸上均伴有明显的塑性变形，这使富含亚稳sp ^3的相不稳定，从而导致重新混合的摩擦材料的数量急剧增加。此外，在这种情况下，还会发现气缸表面明显变粗糙，材料不对称转移并产生磨损碎屑。对于b  = 0.5和1 nm碰撞，可以通过一个简单的几何重叠模型定量地描述第三体体积的演化，该模型假定滑动诱导的相变位于两个粗糙之间。对于b = 2 nm，该模型低估了第三者的体积超过150％，这表明在严重DLC / DLC粗糙碰撞的简单几何模型中必须考虑可塑性。