In recent decades,many additives with difierent characteristics have been applied to strengthen and toughen Al_2O_(3)一based ceramic cutting tool materials.Among them,SiC whiskers and SiC nanoparticles showed excellen...In recent decades,many additives with difierent characteristics have been applied to strengthen and toughen Al_2O_(3)一based ceramic cutting tool materials.Among them,SiC whiskers and SiC nanoparticles showed excellent performance in improving the material properties.W hile no attempts have been made to add SiC whiskers and SiC nanoparticles together into the ceramic matrix and the synergistically toughening efects of them have not been studied.An Al_2O_(3)一SiCw-SiCno advanced ceramic cutting tool material is fabricated by adding both one--dimensional SiC whiskers and zero--dimensional SiC nanoparticles into the Al_2O_(3)matrix with an efective dispersing and mixing process.The composites with 25 vo1%SiC whiskers and 25 vo1%SiC nanoparticles alone are also investegated for comparison purposes.Results show that the Al_2O_(3)一SiCw-SiCno composite with both 20 vo1%SiC whiskers and 5 vo1%SiC nanoparticles additives have much improved mechanical properties.The flexural strength of Al_2O_(3)-SiCw-SiCⅡD is 730~95 MPa and fracture toughness is 5.6±0.6 MPa’m.The toughening and strengthening mechanisms of SiC whiskers and nanoparticles are studied when they are added either individually or in combination.It is indicated that when SiC whiskers and nanoparticles are added together,the grains are further refined and homogenized,so that the microstructure and fracture mode ratio is modified.The SiC nanoparticles are found helpful to enhance the toughening efects of the SiC whiskers.The proposed research helps to enrich the types of ceramic cutting too1 and is benefit to expand the application range of ceramic cutting too1.展开更多
As a natural and environmentally friendly renewable material,Northeast China ash wood(NCAW)(Fraxinus mandshurica Rupr.)was cut by water-jet assisted CO_(2) laser(WACL),the surface quality was evaluated by surface roug...As a natural and environmentally friendly renewable material,Northeast China ash wood(NCAW)(Fraxinus mandshurica Rupr.)was cut by water-jet assisted CO_(2) laser(WACL),the surface quality was evaluated by surface roughness of cut section.The surface roughness was measured by three-dimensional(3D)profilometry.Furthermore,the micromorphology of machined surface was observed by scanning electronic microscopy(SEM).Carbon content changes of machined surface were measured by energy dispersive spectrometer(EDS).A relationship between surface roughness and cutting parameters was established using response surface methodology(RSM).It is concluded that the cutting speed,laser power and water pressure played an important role in surface roughness of cut section.The surface roughness increased as an increase in laser power.It decreased caused by increasing of cutting speed and water pressure.Measurements revealed that the surface quality of NCAW part was improved using the optimized combination of cutting parameters.The established quadratic mathematical model of a good prediction is helpful for matching suitable cutting parameters to obtain expected surface quality.展开更多
基金Supported by National Natural Science Foundation of China(Grant No.51175305)
文摘In recent decades,many additives with difierent characteristics have been applied to strengthen and toughen Al_2O_(3)一based ceramic cutting tool materials.Among them,SiC whiskers and SiC nanoparticles showed excellent performance in improving the material properties.W hile no attempts have been made to add SiC whiskers and SiC nanoparticles together into the ceramic matrix and the synergistically toughening efects of them have not been studied.An Al_2O_(3)一SiCw-SiCno advanced ceramic cutting tool material is fabricated by adding both one--dimensional SiC whiskers and zero--dimensional SiC nanoparticles into the Al_2O_(3)matrix with an efective dispersing and mixing process.The composites with 25 vo1%SiC whiskers and 25 vo1%SiC nanoparticles alone are also investegated for comparison purposes.Results show that the Al_2O_(3)一SiCw-SiCno composite with both 20 vo1%SiC whiskers and 5 vo1%SiC nanoparticles additives have much improved mechanical properties.The flexural strength of Al_2O_(3)-SiCw-SiCⅡD is 730~95 MPa and fracture toughness is 5.6±0.6 MPa’m.The toughening and strengthening mechanisms of SiC whiskers and nanoparticles are studied when they are added either individually or in combination.It is indicated that when SiC whiskers and nanoparticles are added together,the grains are further refined and homogenized,so that the microstructure and fracture mode ratio is modified.The SiC nanoparticles are found helpful to enhance the toughening efects of the SiC whiskers.The proposed research helps to enrich the types of ceramic cutting too1 and is benefit to expand the application range of ceramic cutting too1.
基金This research was supported by the Applied Technology Research and Development Project in Heilongjiang Province of China(GA19A402)Fundamental Research Funds for the Central Universities(2572018CG06).
文摘As a natural and environmentally friendly renewable material,Northeast China ash wood(NCAW)(Fraxinus mandshurica Rupr.)was cut by water-jet assisted CO_(2) laser(WACL),the surface quality was evaluated by surface roughness of cut section.The surface roughness was measured by three-dimensional(3D)profilometry.Furthermore,the micromorphology of machined surface was observed by scanning electronic microscopy(SEM).Carbon content changes of machined surface were measured by energy dispersive spectrometer(EDS).A relationship between surface roughness and cutting parameters was established using response surface methodology(RSM).It is concluded that the cutting speed,laser power and water pressure played an important role in surface roughness of cut section.The surface roughness increased as an increase in laser power.It decreased caused by increasing of cutting speed and water pressure.Measurements revealed that the surface quality of NCAW part was improved using the optimized combination of cutting parameters.The established quadratic mathematical model of a good prediction is helpful for matching suitable cutting parameters to obtain expected surface quality.
