Friction of smooth surfaces with ultrafine particles in the clearance

Friction force between a spherical slider and a smooth flat surface of mica, glass, silicon, sitall, sapphire, metal or diamond-like coating has been measured at reciprocating motion. The slider was made of steel or sapphire. It was revealed that higher surface microhardness of the samples gave lower friction coefficient. An attempt to model friction process of a precision joint in the presence of wear particles in the contact zone was undertaken. For this purpose, ultrafine diamond particles (UFD) were introduced into the friction zone. The friction coefficient increased nonmonotonously with the sample surface microhardness. This fact is explained by abrasive action of the particles and prevailing component deformation in friction. A possibility of reducing the effect of hard particles on friction coefficient has been demonstrated with the surface microrelieves, which contain peak textures.