Silicon carbide/pyrolytic carbon (SiC/PyC) composite materials with excellent performance of self-lubrication and wear resistance were prepared on SiC substrates by electromagnetic-field-assisted chemical vapor infilt...Silicon carbide/pyrolytic carbon (SiC/PyC) composite materials with excellent performance of self-lubrication and wear resistance were prepared on SiC substrates by electromagnetic-field-assisted chemical vapor infiltration (CVI). The composition and microstructure of the SiC/PyC materials were investigated in detail by XRD, SEM and EDS, etc. The effects of the deposition temperature on the section features and wear resistance of the SiC/PyC were studied. The results show that the PyC layers were deposited onto SiC substrates spontaneously at a lower deposition temperature. The SiC substrates deposited with PyC can significantly reduce the wear rate of the self-dual composite materials under dry sliding condition. The wear tests suggest that the SiC/PyC composite materials own a better wear resistance property when the deposition temperature is 800 °C, and the wear rate is about 64.6% of that without the deposition of PyC.展开更多
The(Cu−10Sn)−Ni−MoS2 composites,prepared by powder metallurgy,were studied for the effects of Ni-coated MoS2 on the microstructure,mechanical properties and lubricating properties.The mechanism of effects of Ni and Mo...The(Cu−10Sn)−Ni−MoS2 composites,prepared by powder metallurgy,were studied for the effects of Ni-coated MoS2 on the microstructure,mechanical properties and lubricating properties.The mechanism of effects of Ni and MoS2 on the properties of composites was analyzed through a comparative experiment by adding Ni and MoS2 separately.The results show that the nickel wrapping around the MoS2 particles decreases the reaction rate of MoS2 with the copper matrix,and greatly improves the bonding of the matrix.The composites with 12 wt.%Ni-coated MoS2(C12)show the optimum performance including the mechanical properties and tribological behaviors.Under oil lubrication conditions,the friction coefficient is 0.0075 with a pressure of 8 MPa and a linear velocity of 0.25 m/s.The average dry friction coefficient,sliding against 40Cr steel disc,is measured to be 0.1769 when the linear velocity and pressure are 0.25 m/s and 4 MPa,respectively.展开更多
In all machining processes, tool wear is a natural phenomenon and it leads to tool failure. The growing demands for high productivity of machining need use of high cutting velocity and feed rate. Such machining inhere...In all machining processes, tool wear is a natural phenomenon and it leads to tool failure. The growing demands for high productivity of machining need use of high cutting velocity and feed rate. Such machining inherently produces high cutting temperature, which not only reduces tool life but also impairs the product quality. Metal cutting fluid changes the performance of machining operations because of their lubrication, cooling and chip flushing functions, but the use of cutting fluid has become more problematic in terms of both employee health and environmental pollution. The minimization of cutting fluid also leads to economical benefits by way of saving lubricant costs and workpiece/tool/machine cleaning cycle time. The concept of minimum quantity lubrication (MQL) has been suggested since a decade ago as a means of addressing the issues of environmental intru- siveness and occupational hazards associated with the airborne cutting fluid particles on factory shop floors. This paper deals with experimental investigation on the role of MQL by vegetable oil on cutting temperature, tool wear, surface roughness and dimen- sional deviation in turning AISI-1060 steel at industrial speed-feed combinations by uncoated carbide insert. The encouraging results include significant reduction in tool wear rate, dimensional inaccuracy and surface roughness by MQL mainly through reduction in the cutting zone temperature and favorable change in the chip-tool and work-tool interaction.展开更多
基金Project(2011CB605801)supported by the National Basic Research Program of ChinaProject(2011M500127)supported by the China Postdoctoral Science Foundation+2 种基金Projects(51102089,50802115)supported by the National Natural Science Foundation of ChinaProjects(12JJ4046,12JJ9014)supported by the Natural Science Foundation of Hunan Province,ChinaProject(74341015817)supported by the Post-doctoral Fund of Central South University,China
文摘Silicon carbide/pyrolytic carbon (SiC/PyC) composite materials with excellent performance of self-lubrication and wear resistance were prepared on SiC substrates by electromagnetic-field-assisted chemical vapor infiltration (CVI). The composition and microstructure of the SiC/PyC materials were investigated in detail by XRD, SEM and EDS, etc. The effects of the deposition temperature on the section features and wear resistance of the SiC/PyC were studied. The results show that the PyC layers were deposited onto SiC substrates spontaneously at a lower deposition temperature. The SiC substrates deposited with PyC can significantly reduce the wear rate of the self-dual composite materials under dry sliding condition. The wear tests suggest that the SiC/PyC composite materials own a better wear resistance property when the deposition temperature is 800 °C, and the wear rate is about 64.6% of that without the deposition of PyC.
基金Projects(51371099,51501091)supported by the National Natural Science Foundation of China。
文摘The(Cu−10Sn)−Ni−MoS2 composites,prepared by powder metallurgy,were studied for the effects of Ni-coated MoS2 on the microstructure,mechanical properties and lubricating properties.The mechanism of effects of Ni and MoS2 on the properties of composites was analyzed through a comparative experiment by adding Ni and MoS2 separately.The results show that the nickel wrapping around the MoS2 particles decreases the reaction rate of MoS2 with the copper matrix,and greatly improves the bonding of the matrix.The composites with 12 wt.%Ni-coated MoS2(C12)show the optimum performance including the mechanical properties and tribological behaviors.Under oil lubrication conditions,the friction coefficient is 0.0075 with a pressure of 8 MPa and a linear velocity of 0.25 m/s.The average dry friction coefficient,sliding against 40Cr steel disc,is measured to be 0.1769 when the linear velocity and pressure are 0.25 m/s and 4 MPa,respectively.
基金Project (No. DEARS/CASR/R-01/2001/D-934 (30)) supported by Directorate of Advisory Extension and Research Services (DAERS), Committee for Advanced Studies & Research (CASR), BUET, Dhaka, Bangladesh
文摘In all machining processes, tool wear is a natural phenomenon and it leads to tool failure. The growing demands for high productivity of machining need use of high cutting velocity and feed rate. Such machining inherently produces high cutting temperature, which not only reduces tool life but also impairs the product quality. Metal cutting fluid changes the performance of machining operations because of their lubrication, cooling and chip flushing functions, but the use of cutting fluid has become more problematic in terms of both employee health and environmental pollution. The minimization of cutting fluid also leads to economical benefits by way of saving lubricant costs and workpiece/tool/machine cleaning cycle time. The concept of minimum quantity lubrication (MQL) has been suggested since a decade ago as a means of addressing the issues of environmental intru- siveness and occupational hazards associated with the airborne cutting fluid particles on factory shop floors. This paper deals with experimental investigation on the role of MQL by vegetable oil on cutting temperature, tool wear, surface roughness and dimen- sional deviation in turning AISI-1060 steel at industrial speed-feed combinations by uncoated carbide insert. The encouraging results include significant reduction in tool wear rate, dimensional inaccuracy and surface roughness by MQL mainly through reduction in the cutting zone temperature and favorable change in the chip-tool and work-tool interaction.
