Manufacture And Cutting Properties Of CVD Diamond Coated Circular Saw Blades

Combined with the property of diamond,CVD diamond coated cutting tools have excellent mechanical properties,tribological properties,thermal conductivity and chemical inertness,which make them have excellent performance in cutting field.Due to the outstanding performance,CVD diamond coated cutting tools have brilliant prospect in cutting field.Usually,a uniform film is desirable for coated tools due to the better performance.However,it is difficult to obtain when come to cutters with complex shape,especially to sheet type tools.In this thesis,we studied how to obtain high quality diamond film on circular saw blades using hot filament chemical vapor deposition(HFCVD).Firstly,some key problems in the processes of pretreatment and deposition were investigated.Then,we did research on how to obtain uniform diamond coatings on circular saw blades.The main work and results are as follows:1.The effect of pretreatment process on the substrate morphology,film quality and adhesion was studied.The results show that the influence of Murakami solvent on substrates is limit when the reaction time is over 15 min.And acid treatment has a big impact on quality of diamond films.Inadequate reaction time results in poor quality diamond films and poor adhesion.Overlong reaction time results in loose surface and poor adhesion.2.Different diamond coatings were obtained under different deposition parameters(carbon source concentration,pressure,the distance between filaments and substrates,as well as the power of filaments).Scanning electron microscope(SEM)and Raman spectrometer were used to characterize the diamond films.Some conclusions about the influence of deposition parameters on the quality and grain size of diamond films were drew.Pressure at 3 kPa is suitable for depositing microcrystalline diamond films.In order to obtain nanocrystalline diamond films,it is better to reduce the pressure and increase the concentration of carbon source.Diamond with the orientation of(100)is obvious when the distance between hot filaments and substrates is 8 mm.3.The diamond coated circular saw blades were prepared.The suitable method of placing the saw blade was studied.In order to obtain a more uniform diamond film on the circular saw blade,the temperature field in the chamber was improved by reflectors,which was confirmed by the results of experiments and simulation.Diamond coated circular saw blades were fabricated by different processes,and industrial cutting experiments were carried out to exam the lifetime of the cutters.The results of cutting experiments show that the service life of the diamond coated circular saw blades can be increased by 5-10 times than uncoated tools.The cause of failure was analyzed,the results show that microcrystalline diamond film is suitable for circular saw blades,and the film thickness at 5-7 ?m is preferred.In addition,there is still much room for improving the service life of diamond coated cutters.