Influence of various types of clays on velocity dependence of friction composites

The stick-slip phenomena of various types (halloysite, montmorillonite and wollastonite) of clay-based composite friction materials were evaluated in terms of their velocity-dependent friction response. Scanning electron microscopy of the contact patches suggested breakage of contact plateaus in the composites with halloysite, whereas relatively small contact patches were developed in montmorillonite-based friction composites. The presence of relatively harder ingredients such as magnesium oxide and iron particles on the worn surface have contributed to the stick-slip phenomenon. The presence of wollastonite in the composites leads to the ploughing effect during sliding. The intensity of creep groan remained controlled by the shear strength of the interfacial junction involving asperity contact/welding whereas dynamic groan remains predominated by the stiffness of the composites.