Study Of Preparation And Performance Of Muitilayer Diamond Coated Tool

Diamond is atomic crystals with sp~3 structure and FCC structure,which is high hardness,wear resistance,so it is the best choice for hard coating materials of high-end tool.Diamond coating tools widely used in aerospace,automotive,electronics and other fields,cutting high silicon aluminum alloy,ceramics,carbon fiber reinforcing materials,graphite,etc.show excellent cutting performance.In this paper,hot filament chemical vapor deposition method(HFCVD)is used to deposite single-layer and multi-layer diamond coatings with different structures on tungsten carbide tools.Scanning electron microscope(SEM),X-ray diffractometer(XRD)and Raman spectroscopy(Raman)were used.Atomic force microscopy(AFM)was used to characterize the diamond coating structure.Raman spectrometer and X-ray diffractometer were used to analyze the stress of the coating structure.The indentation experiment system was used to study the bonding properties of diamond coating and tungsten carbide cemented carbide of different structures.Employ of machining center system to study the cutting performance of different structural diamond-coated tools,and preliminary exploration of the diamond coating shedding mechanism.In this paper,the study on the growth of diamond deposited by hot filament chemical vapor deposition shows that with the increase of substrate temperature,chamber pressure and methane concentration,the growth rate of diamond coating increases,and the concentration of methane has the most obvious effect on the growth quality of diamond.With the increase of methane concentration,the surface of the diamond coating is reduced from 1-3 micron diamond grains to several tens of nanometers.Due to the refinement of the surface diamond grains,the coating roughness tends to decrease,and carbon phase also increases.The diamond coating structure transforms from a columnar growth mode to a nano-pile growth mode.By adjusting the concentration of methane,multi-layer diamond films with different cycle(600nm,300 nm and 100 nm)was successfully depositedIn this paper,systematic study of the residual stress and coating properties of different structural diamond coatings shows that the residual stress of microdiamond coating is the largest,which is-3.06 GPa.But there is a strong mechanical locking effect between micro-diamond and cemented carbide substrate.Residual stress of nano-diamond coating is the smallest,which is-2.27 GPa.But the nanodiamond forms a large amount of sp~2 carbon at the interface of the cemented carbide,and has the worst bonding performance with the substrate.Due to the introduction of nano-diamond coating,the multilayered diamond coating has reduced the residual stress to-2.55 GPa and improved the toughness of the coating compared to the micro-diamond coating.The performance of the multi-layered structure with a growth cycle of 300 nm is outstanding after the indentation test.In this paper,a systematic study of the cutting performance of diamond-coated tools with different structures revealed that except for a multilayered diamond tool with a modulation period of 100 nm,the cutting performance of a multi-layered diamond tool is better than that of a single-layered diamond-coated tool.with modulation at 300 nm.,the coating performance of the cycle was the best,When the cutting length was 1130 m,the blade coating remained intact.The singlelayer diamond tool showed significant coating shedding at the initial cutting.Through the observation of the damage of the coating at the cutting edge,it was found that the microdiamond coating was flaking due to the large brittleness and dissociated by the columnar crystal;the multilayer diamond coating had high toughness,and the early coating was consumed in the form of abrasion,when it wears to a certain thickness,the shear force applied to the coating suddenly increases,causing large areas of the coating to fall off.According to the above multi-layer diamond coating damage mechanism,the preparation process of the multilayer diamond coating can be optimized next step,the overall thickness of the coating can be increased,or the thickness of the single-layer micro diamond can be increased to increase the wear resistance of the coating.