Characterization of diamond cutting tools with carbon nanofiber

The matrix selection of diamond cutting tools is an important criterion that affects the cutting quality. If the matrix is too ductile or too hard, it negatively affects the cutting quality. When the literature is examined, many different matrix combinations have been used. However, there is hardly any use of nanoscale particles or fibers. Taking advantage of this deficiency, this thesis study has been directed. In this thesis study, carbon nanofiber (CNF) was added in different percentages (0; 0,25; 0,50; 0,75 and 1,00) by weight into the bronze (85% wt Cu + 15% wt Sn) matrix. Hot pressing method has been preferred as the production method; The samples were produced under 680 °C sintering temperature, 4 minutes sintering time and 35 MPa pressure. The microstructure, hardness, density properties and transverse rupture strength of the produced samples were investigated. Microstructural investigations and phase composition were done by optical microscopy, scanning electron microscopy and X-ray diffraction. Hardness measurements were made with a microhardness device. Three-point bending tests were carried out using a universal tensile tester. The corrosion behavior of the samples was determined by potentiodynamic measurements. Microstructure photographs have shown that low amounts of CNF are relatively homogeneous in the bronze matrix, but aggregated in clusters in certain regions in high amounts. According to XRD analysis, α-Cu, Cu3Sn and C phases were formed in the structure. With increasing CNF amounts, there was a significant increase in hardness, but the change in relative densities was not much. While the highest amount of 0,25% CNF was detected in the transverse rupture strength, there was a decrease in these values with increasing CNF amounts. It was determined that the SEM photographs taken from the fractured surfaces of the CNF-added samples were mainly formed by intergranular separation. In some rare regions, it has been observed that ductile fracture dominated by plastic deformation occurs. As the CNF ratio in the samples increased, there was a decrease in corrosion resistance due to the microgalvanic effect.