This application note devotes to characterization of diamond coating tools by confocal Raman and photoluminescence techniques using Confotec® MR520 microscope (SOL instruments).
The investigated tool contains diamond grains fixed on the functional part via a bonding material. Approximate micron range of diamond micro-crystals is 15 – 25 µm Raman and NV photoluminescence images of tool (150×150 µm) are shown in Fig.2. It is possible to see from the experimental data, there is homogeneous distribution of diamond grains along the working surface of a tool (Fig.2a). From analysis of the intensity of NV photoluminescence peak (Fig.2b) we can conclude that diamond crystals have got varied contents of defects. Some of crystals include a small amount of defects. Such crystals are marked with the white circles in Fig.2.
One more detailed measurement of the tool (70×70 µm area) is shown in Fig.3. Measurement result on this area is similar to the previous one: distribution of diamond grains along the working surface is uniform (Fig.3a,b), and concentration of defects in diamond micro-crystals is significant (Fig.3d). The position of diamond line (Fig.3c) illuminates the strain distribution in different grains. Red color on the stress map (Fig.3c) represents regions with compressive stress. Micro-crystals with the increased stress are marked in Fig.3 with dash-dot circles.