Cemented carbide cutting tools life with nanocrystalline Al2O3 layer deposited by MOCVD

The work presents the results of tool life tests of uncoated cemented carbide cutting tools as well as tools coated with Al2O3-C and Al2O3-C/Al2O3 composite layer synthesized by MOCVD method using Al(acac)3. Al2O3-C layers were deposited in argon. The composite layer was synthesized in argon initially in order to obtain thin and continuous Al2O3-C layer about 70 nm thick and outer, thicker pure Al2O3 layer deposited in air. The layers were deposited at 800 °C. Same samples were additionally annealed or synthesized at 1000 °C. The most advantageous results were obtained when the layers were annealed. This way enables controlling the grain size in the layer. In the work, comparative tool life tests were also performed for commercial cemented carbide cutting tools without and with Ti(C, N) + Al2O3 layers from Sandvik Baildonit.