Study on tribology and cutting performance of boron doped diamond composite coated tool

Abstract

Microcrystalline diamond (MCD), nanocrystalline diamond (NCD), boron doped microcrystalline diamond (BDMCD), and boron doped microcrystalline-nanocrystalline diamond (BDM-NCD) films were prepared by hot filament chemical vapor deposition (HFCVD) technique. Scanning electron microscopy (SEM), Raman spectroscopy and Rockwell indention testes were used to characterize the microstructure and properties of the coatings, and friction experiments were carried out to study the tribological properties of diamond films and GCr15 steel balls under different lubrication conditions. At the same time, the cutting performance of different diamond coated tools was studied by cutting 30% SiCp/Al composites. The results show that the residual compressive stress of the NCD film is the largest, which is −1.88 GPa. Due to the mitigation effect of the underlying BDMCD film, the BDM-NCD film has the smallest residual stress, which is −0.37 GPa. It can be seen from the friction test that the average coefficient of friction of NCD film is lower than that of MCD film due to the smooth surface. The average friction coefficient of BDM-NCD film is the lowest, which is 0.326. At the same time, the wear resistance of BDM-NCD film is the best, and the value is 0.53×10−6 mm3/Nmm. From the wear morphology, it can be seen that the amount of metastatic material adhered to the wear surface of the diamond films is less under water lubrication than under dry friction condition. Compared with dry friction, the wear scar depth of BDM-NCD film under water lubrication is smaller, showing the better tribological properties. Cutting experiments show that BDM-NCD film has the best wear resistance and the best cutting performance.