Hard-material Adhesion: Which Scales of Roughness Matter?
Hard-material Adhesion: Which Scales of Roughness Matter?
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DOI：
10.1007/s11340-021-00733-6
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发表时间：
2021-07
影响因子：
2.4
通讯作者：
L. A. Thimons;A. Gujrati;A. Sanner;Lars Pastewka;T. Jacobs
中科院分区：
文献类型：
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作者：
L. A. Thimons;A. Gujrati;A. Sanner;Lars Pastewka;T. Jacobs
背景表面形貌强烈改变硬质材料接触的粘附力，但实际表面的粗糙度通常存在于许多长度尺度上，并且尚不清楚这些尺度中哪一个具有最强的影响。目的：本研究旨在确定哪些形貌尺度对宏观粘附力影响最强。方法使用足够大（直径 0.5 毫米）的球形红宝石探针对不同粗糙度的技术相关金刚石涂层进行粘附力测量，该探针足够大（直径 0.5 毫米），可以对所有长度尺度的形貌进行采样。对于每种材料，进行了 2000 多次拉脱力测量，以研究粘附力的大小和统计分布。使用球体接触模型，测量了四个表面上与粗糙度相关的粘附功有效值，范围为 0.08 至 7.15 mJ/m2。使用数值分析可以更准确地拟合数据，其中将相互作用势积分到 AFM 测量的所有接触表面的形貌上。结果这些计算表明，考虑材料中的纳米级塑性对于测量的良好定量拟合至关重要，并且在测试后通过探针的 AFM 测量证实了这种塑性的存在。该分析能够提取与几何形状无关的材料参数；红宝石和金刚石之间的固有粘附功经测定为 46.3 mJ/m2。粘附范围为 5.6 nm，比通常假设的原子相互作用要长，但与最近的其他研究结果一致。最后，对相同的表面重复进行数值分析，但这次包含或过滤掉不同长度尺度的粗糙度。结论结果表明，长度尺度的临界带（横向尺寸在 43 nm 到 1.8 µm 之间）对这些坚硬、粗糙接触的总粘合力具有最强的影响。
BackgroundSurface topography strongly modifies adhesion of hard-material contacts, yet roughness of real surfaces typically exists over many length scales, and it is not clear which of these scales has the strongest effect. Objective: This investigation aims to determine which scales of topography have the strongest effect on macroscopic adhesion.MethodsAdhesion measurements were performed on technology-relevant diamond coatings of varying roughness using spherical ruby probes that are large enough (0.5-mm-diameter) to sample all length scales of topography. For each material, more than 2000 measurements of pull-off force were performed in order to investigate the magnitude and statistical distribution of adhesion. Using sphere-contact models, the roughness-dependenteffectivevalues of work of adhesion were measured, ranging from 0.08 to 7.15 mJ/m2across the four surfaces. The data was more accurately fit using numerical analysis, where an interaction potential was integrated over the AFM-measured topography of all contacting surfaces.ResultsThese calculations revealed that consideration of nanometer-scale plasticity in the materials was crucial for a good quantitative fit of the measurements, and the presence of such plasticity was confirmed with AFM measurements of the probe after testing. This analysis enabled the extraction of geometry-independent material parameters; theintrinsicwork of adhesion between ruby and diamond was determined to be 46.3 mJ/m2. The range of adhesion was 5.6 nm, which is longer than is typically assumed for atomic interactions, but is in agreement with other recent investigations. Finally, the numerical analysis was repeated for the same surfaces but this time with different length-scales of roughness included or filtered out.ConclusionsThe results demonstrate a critical band of length-scales—between 43 nm and 1.8 µm in lateral size—that has the strongest effect on the total adhesive force for these hard, rough contacts.