Measurement of Friction Coefficient on a Powder Layer and Fluid Dynamic Study

Results of comparison experiments ~ A kind of powder material

When starch was used as the powder material, the slide contains three phase observed in the runs in which flour was used. mB range from 0.072 to 0.078; this was smaller than mB for flour (from 0.11 to 0.15).

When silica sand was used, the slide condition and deceleration could not be observed clearly because the disk raised a cloud of powder (Movie 6). m* was 0.61-0.73; it was larger than the friction coefficient without the powder layer.
Movie 5. Sliding on the starch layer.
Fig. 16. Friction coefficient versus basal pressure of the disk.
:m B for dogtooth violet starch layer
:m B for flour layer
:m B for  flour layer in another month
:without flour layer

Movie 6. Sliding on the silica sand layer.
Measurement of Friction Coefficient on a Powder Layer and Fluid Dynamic Study