Wear Mechanism of Cast Iron Piston Ring/Aluminum Matrix Composite Cylinder Liner

This article presents the effect of stereological parameters of graphite precipitations in GJL 350 cast iron and reinforcing fibers in AC-47000 + 10% A(F) composite on the wear mechanism of piston ring-cylinder liner contacts in a combustion engine. A finite element method was applied to explain the wear mechanisms. On the basis of the investigations performed on stereological parameters of graphite and fiber precipitates, it was possible to elaborate the models and perform computation of stress distribution and local strains at the point of contact between graphite and fibers. The calculations proved that the values of local stresses around fibers are several times higher than the permissible stresses. This leads to graphite spalling, fiber breakage, decohesion on the fiber-matrix boundary, as well as the removal of fibers broken during the process of machining. Once the fibers are removed, the local contact of cast iron and matrix material occurs, which is accompanied by an increase in the friction coefficient. After partial wear of the matrix, new fibers well connected to the matrix are exposed and the friction coefficient is stabilized.