Evaluation of Nanoscale Friction Depth Distribution in ZDDP and MoDTC Tribochemical Reacted Films Using a Nanoscratch Method
Evaluation of Nanoscale Friction Depth Distribution in ZDDP and MoDTC Tribochemical Reacted Films Using a Nanoscratch Method
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使用纳米划痕法评估 ZDDP 和 MoDTC 摩擦化学反应膜中的纳米级摩擦深度分布
DOI：
10.1023/b:tril.0000009720.47177.f2
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发表时间：
2004
影响因子：
3.2
通讯作者：
Y. Yasuda
中科院分区：
文献类型：
--
作者：
Jiping Ye;M. Kano;Y. Yasuda
利用纳米划痕方法结合原位 AFM 观察，成功评估了 MoDTC/ZDDP 和 ZDDP 摩擦膜的局部摩擦系数相对于深度和表面附近的分布。结果发现，两种摩擦膜都是摩擦功能梯度材料。随着划痕深度从 60 nm 减小到 10 nm，摩擦系数从 0.35 减小到 0.16。据观察，MoDTC/ZDDP 和 ZDDP 摩擦膜在表面附近具有不同的剪切强度水平，这可以通过它们在 2 至 10 nm 划痕深度范围内表现出的不同谷形摩擦系数分布来证明。根据我们最近的纳米力学测量，这一观察结果表明，两种摩擦膜在表面以下约 10 nm 的深度处都具有超低摩擦的内皮层。最重要的是，MoDTC/ZDDP 摩擦膜的内皮层比 ZDDP 摩擦膜具有更低的摩擦系数（0.084 比 0.104）并且更薄（约 3.2 nm 比 6.4 nm）。因此，这些结果表明，MoDTC 添加剂引起的摩擦减少源于 MoDTC/ZDDP 和 ZDDP 摩擦膜内皮层的不同摩擦行为。这些纳米划痕结果与我们最近通过纳米压痕测量检测这些摩擦膜之间机械性能差异的工作结果一致。
The distributions of local friction coefficients relative to the depth and near the surface of MoDTC/ZDDP and ZDDP tribofilms were successfully evaluated by using a nanoscratch method combined with in situ AFM observation. It was found that both tribofilms were friction-functionally graded materials. The friction coefficients decreased from 0.35 to 0.16 with a decrease in the scratch depth from 60 to 10 nm. It was observed that the MoDTC/ZDDP and ZDDP tribofilms possessed different shear strength levels near the surface as evidenced by the different valley-shaped friction coefficient distributions they exhibited for scratch depths ranging from 2 to 10 nm. Based on our recent nanomechanical measurements, this observation indicated that both tribofilms possessed an ultra-low friction inner skin layer at a depth of about 10 nm below the surface. Most importantly, the inner skin layer of the MoDTC/ZDDP tribofilm possessed a lower friction coefficient than that of the ZDDP tribofilm (0.084 versus 0.104) and was thinner (about 3.2 nm versus 6.4 nm). These results thus revealed that the reduction in friction attributed to the MoDTC additive originates from the different friction behavior of the inner skin layers of the MoDTC/ZDDP and ZDDP tribofilms. These nanoscratch results agree with the findings of our recent work on detecting differences in mechanical properties between these tribofilms by nanoindentation measurements.