It is commonly assumed that van der Waals forces dominate adhesion in dry systems and electrostatic forces are of second order importance and can be safely neglected. This is unambiguously the case for particles interacting with flat surfaces. However, all surfaces have some degree of roughness. Here we calculate the electrostatic and van der Waals contributions to adhesion for a polarizable particle contacting a rough conducting surface. For van der Waals forces, surface roughness can diminish the force by several orders of magnitude. In contrast, for electrostatic forces, surface roughness affects the force only slightly, and in some regimes it actually increases the force. Since van der Waals forces decrease far more strongly with surface roughness than electrostatic forces, surface roughness acts to increase the relative importance of electrostatic forces to adhesion. We find that for a particle contacting a rough conducting surface, electrostatic forces can be dominant for particle sizes as small as ∼1–10 μm.

中文翻译：

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静电和范德华力在颗粒粘附到粗糙导电表面上的相对重要性

通常认为范德华力在干燥系统中占主导地位，而静电力是次要的，可以安全地忽略。颗粒与平面相互作用的情况无疑是这样。但是，所有表面都具有一定程度的粗糙度。在这里，我们计算了静电和范德华力对与粗糙导电表面接触的可极化颗粒的附着力的影响。对于范德华力而言，表面粗糙度可以使该力减小几个数量级。相反，对于静电力，表面粗糙度仅轻微影响力，在某些情况下，它实际上会增加力。由于范德华力在表面粗糙度下的降低远比静电力大得多，表面粗糙度起到增加静电力对粘附的相对重要性的作用。我们发现，对于接触粗糙导电表面的颗粒，静电力可能对小至约1–10μm的颗粒占主导地位。