| With the development of green cutting technology,clean production has become a key direction in the field of processing and manufacturing.As a new direction of ceramic tool research,self-lubricating ceramic tool is an important innovative means in dry machining.As an emerging green lubrication technology,nanofluids minimum quantity lubrication also has unique advantages.Therefore,the combination of nanofluids minimum quantity lubrication and ceramic tool solid lubrication provides a new idea for processing technology.In this thesis,SiC nanofluids with different mass fractions were prepared by two-step method using SiC as a fluid hard particle additive and rapeseed oil as were prepared by two-step method.According to the thermal properties of SiC nanofluids with different mass fractions,including viscosity,wettability and thermal conductivity,the influence of nanofluids on thermal properties under different mass fractions was analyzed,which provided a leading analysis for the nanofluids micro-lubrication cutting experiment of ceramic tools.By designing the cutting experiments of nanofluids and self-lubricating ceramic tools,the synergistic effect of SiC nanofluids and solid lubrication of ceramic tools under micro-lubrication was studied.The results show that SiC nanofluids can reduce the wear,cutting temperature and surface roughness of ceramic tools by 55.1%,41.5%and 19.2%,respectively,and the friction coefficient is reduced by 19.9%.In addition,according to the experimental results of SiC nanofluids with different particle sizes on the cutting life of ceramic tools,it is found that when the fluid particles are at the nano level,the tool life is improved by about 44.4%～46.7%compared with dry cutting,and compared with pure rapeseed oil,it is improved by about 7.9%～9.6%,which proves the effectiveness and stability of SiC nanofluids in improving the machining performance of traditional ceramic tools.By designing the cutting experiments of nanofluids and self-lubricating ceramic tools,the synergistic effect of SiC nanofluids and solid lubrication of ceramic tools under micro-lubrication was studied.The results show that the cutting force of Al2O3/GNPs self-lubricating tool is significantly lower than that of Al2O3 tool,and the average friction coefficient of the two tools is compared.It is found that the friction coefficient of Al2O3/GNPs tool under dry cutting is also lower than that of Al2O3 tool,which proves that the anti-friction effect of solid lubricant in the tool is an important reason for the decrease of friction coefficient.On this basis,the friction coefficients of Al2O3 and Al2O3/GNPs tools under different lubrication environments were compared.It was found that the friction coefficient of Al2O3 tool under SiC-NMQL condition was 33.1%,40.1%,28.9%lower than that of dry cutting,and 33.2%,37.8%,24.2%lower than that of MQL,while Al2O3/GNPs tool was 27%,20.4%,5.7%lower than dry cutting,and 24.4%,15.5%,7.9%lower than MQL.Based on the cutting temperature,cutting life and surface quality of the cutting tool,the results show that the ceramic cutting tool is superior to the single lubrication under the synergistic lubrication,and the cutting performance of the ceramic cutting tool is obviously improved.Finally,through the study of the synergistic mechanism of solid lubrication and nanofluids of ceramic tools,it is found that the precipitation of graphene and the formation of a lubricating layer during cutting,as well as the polishing and anti-friction effects of SiC nanoparticles,reduce the material adhesion of the workpiece to the tool surface,reduce the friction coefficient and reduce the generation of friction heat.The synergistic effect of SiC nanofluids and graphene makes the surface wear of the tool relieved under the combined action of solid lubrication,oil film lubrication and nanofluid lubrication,which prolongs the service life of the tool and effectively improves the surface quality of the workpiece. |
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