Effect of particle morphology on resistance to permanent sinking by normal loading of silicon particle in aluminium matrix of a cast aluminium silicon alloy

In pursuing the mechanics of wear of cast aluminium-silicon alloy engine bore we report here the sinking of load bearing silicon protrusions under normal loading. After establishing the buried depth of particles as a function of measurable plan dimensions we experimentally relate the particle morphology to resistance to permanent sinking into the matrix by normal loading. We find this resistance, expressed as critical contact pressure at the commencement of plasticity, to increase with the surface to volume ratio of the particle being loaded. This implies that small particles enhance resistance to plastic sinking. If the particles are rectangular in shape, thinner particles (needle shaped) offer greater resistance to sinking. The information reported provides a guide to the alloy designer concerned with wear resistance of aluminium engine bores.