Microstructures and properties of CVD TiN-TiCN-Al2O3 coated WC-8wt%Co-xRu cemented carbide

The effect of Ru on microstructures, coating texture changes, mechanical properties improvement, and cutting performance enhancement in CVD TiN-TiCN-Al2O3 coated cemented carbide was investigated in this paper. The results show that with the increasing amount of Ru, the mean grain size of the matrix decreases from 1.28 to 0.95 mu m. The microstructural refinement of the matrix creates more nucleation sites for coating growth, which further reduces the grain size of the coating. Moreover, the Ru, diffusing from the matrix into the coating, changes the growth direction of partial grains. The coated cemented carbide with 1.5wt% Ru shows the largest hardness of 17.8GPa, which results from the combined influence of the reduction in coating grain size and the decrease in the concentration of TiCN coating {111} texture. In the process of turning 17-4PH stainless steel, due to the improved hardness and plastic deformation resistance of the composite coating, as well as enhanced (104) texture of Al2O3 coating, the flank wear of the coated tool with 0.5wt% Ru is 31.25% lower than that without Ru, which exhibits the best cutting performance.