Interaction between the metal and the abrasive in Coulomb friction

Abstract

1. The analysis of the phenomena accompanying Coulomb friction, in particlar, the grinding of materials on grinding wheels, and the specific features of the interaction between solids in contact made it possible to establish the most promising guidelines in searching for the most advantageous combination of materials for Coulomb friction pairs. 2. The modern concepts concerning the electron structure of matter were used as a basis in formulating the requirments for the abrasive material that would be most suitable for grinding certain specific structural materials, such as titanium alloys. These requirements are best satisfied by the electron structure of cubic boron nitride. 3. It has been shown that the existing abrasive materials, including diamond, cannot be used successfully for the grinding of parts made of titanium alloys and that cubic boron nitride (borazon) may prove to be an acceptable abrasive for these purposes, which has been confirmed by the results of experimental investigations. 4. Comparative physical investigations of the surface and the adjacent layers of the VT3-1 titanium alloy, ground on grinding wheels under identical conditions, have shown that the structure defects due to grinding (crushing and reorientation of the grains, the stressed state of the crystal lattice, etc.) extend, in the case of wheels made of cubic boron nitride, to a depth approximately one-half of that reached in the case of grinding wheels made of white electrical corundum. This should bring about a corresponding increase in the strength of parts made of titanium alloys, ground on wheels with cubic boron nitride grains. 5. The distribution of microhardness and residual stresses in the surface layers of the investigated specimens also indicates that surface grinding on cubic boron nitride wheels is preferable with regard to the strength characteristics.