The contribution which was made by disorder to the friction force between a solid film and a substrate, in a micro-balance friction experiment, was calculated by using perturbation methods. It was found that the disorder led to a much larger friction force than did a defect-free interface if the defect concentration was greater than 10-5. It was also independent of the sliding rate.

J.B.Sokoloff: Physical Review B, 1995, 51[21], 15573-4