Fabrication and performance of Al2O3/(W,Ti)C + Al2O3/TiC multilayered ceramic cutting tools

Al2O3/(W,Ti)C+Al2O3/TiC multilayered ceramic cutting tools with different thickness ratios were produced by hot pressing. The residual stresses inside the layered materials during fabrication were calculated by means of the finite element method. The mechanical properties at the outer layer of the layered materials were measured. The cutting performance of the layered tools was investigated and compared with an unstressed reference tool. Results showed that multilayered structure in AWT+AT layered ceramic materials can induce excess residual stresses during fabrication. These residual stresses are compressive in the AWT outer layer and tensile in the AT internal layer. The fracture toughness at the outer layer of the layered ceramic materials is greatly improved compared with that of the stress-free one. These multilayered tools can minimize the flank wear and edge chipping compared with the stress-free tool. The mechanisms responsible were determined to be the formation of compressive residual stress on the outer layer of the layered tools, which led to an increase in resistance to fracture. Thickness ratios were found to have a profound effect on the residual stresses, the fracture toughness, and the cutting performance of the layered tools. (C) 2009 Elsevier B.V. All rights reserved.