Sub-Micrometer Alumina Cutting Ceramics for Continuous and Discontinuous Machining of Hard Materials

The study relates the technical performance of alumina cutting tools on machining chilled cast iron and hardened steel to microstructures and basic mechanical properties. In comparison with advanced commercial grades, tool wear decreases when the grain size of the ceramics is reduced to significantly less than 1 µm. When machining hardened steel at intermediate velocities, sub-micrometer Al2O3/Ti(C,O) composites exhibit the least wear. At higher speeds, however, new alumina tools best withstand the high processing temperatures, and they are also the favourite choice for discontinuous cutting despite their moderate creep resistance and toughness. For machining chilled cast iron, Al2O3 inserts minimise the chemical interaction with the steel and provide a qualitative leap towards reduced flank wear compared with composite ceramics.