In metal cutting applications, coatings are often applied onto cemented carbide inserts as wear and heat resistant protection layers extending the tool life. A commonly used coating on inserts is Al2O3 which provides chemical stability, thermal and wear protection for the cemented carbide insert. The crater wear and plastic deformation behavior in certain applications can be improved by altering the phase and/or texture of the wear protective coating. Worn (0001)-textured α-Al2O3 and κ-Al2O3-TiN multilayer coatings on inserts which had been used in cutting applications have been investigated by means of scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDXS), XRD, electron backscatter diffraction (EBSD) in the SEM and (scanning) transmission electron microscopy ((S)TEM) techniques. The microstructure of the α-Al2O3 coating can be seen in the SE-SEM image and its (0001)-texture is shown in the EBSD orientation map, see Fig. 1a and b. The specimens for (S)TEM characterization were prepared in a Helios NanoLab 650 instrument (FEI Company) equipped with an EBSD detector (NordlysMax2, Oxford Instruments), EDXS detector (X-MaxN, Oxford Instruments) and AZtec software package (Oxford Instruments). (S)TEM characterization was performed using a Titan3 60-300 equipped with ChemiSTEM (FEI Companay). (S)TEM characterization of the worn α-Al2O3 coating revealed a modified region and EDXS elemental maps showed that this region contains Mg, Ca and Si beside the Al and O, see Fig. 2. Also, small grains of Fe were observed below this modified region. For comparison, (S)TEM characterization was performed on the worn κ-Al2O3-TiN multilayer coating. By determining the elemental distribution and formed phases the chemical wear mechanisms can be described.
Figures:
Fig. 1: a) SE-SEM image of the α-Al2O3 coated cemented carbide insert. b) EBSD orientation map with α-Al2O3 grains coloured according to the c-axis orientation, where yellow denotes that the c-axis of the α-Al2O3 grains is parallel to the out-of-plane direction.
Fig. 2: ADF-STEM image (on top) and EDXS elemantal maps (below) of the worn α-Al2O3 coating.
To cite this abstract:
Ernesto Coronel, Arno Meingast, Babak Rabiei, Jeanette Persson, Martina Lattemann; Electron microscopy characterization of the wear of textured α-Al2O3 and κ-Al2O3-TiN multilayer coatings for cutting tool applications. The 16th European Microscopy Congress, Lyon, France. https://emc-proceedings.com/abstract/electron-microscopy-characterization-of-the-wear-of-textured-%ce%b1-al2o3-and-%ce%ba-al2o3-tin-multilayer-coatings-for-cutting-tool-applications/. Accessed: December 3, 2023« Back to The 16th European Microscopy Congress 2016
EMC Abstracts - https://emc-proceedings.com/abstract/electron-microscopy-characterization-of-the-wear-of-textured-%ce%b1-al2o3-and-%ce%ba-al2o3-tin-multilayer-coatings-for-cutting-tool-applications/