Fabrication of the surface micro-texture on the C-plane sapphire is undertaken by a355 nm Ultraviolet(UV)pulsed laser.The surface micro-textures of sapphire with different laser scanning line spacing ranging from 10 l...Fabrication of the surface micro-texture on the C-plane sapphire is undertaken by a355 nm Ultraviolet(UV)pulsed laser.The surface micro-textures of sapphire with different laser scanning line spacing ranging from 10 lm to 100 lm are obtained,where the selection range of scanning line spacing is controlled in the range of the groove width and plasma width to obtain a surface of high Peak-Valley(PV)value.A reasonable processing order is proposed to manufacture different types of surface micro-textures on sapphire by laser ablation trajectory regulation.In the multiple-passes laser ablation of sapphire by the UV nanosecond pulsed laser,the scanning lines in each direction is treated as once scanning.On this basis,the multiple processing can be carried out to avoid the influence of the subsequent scanning on the machined groove.In addition,the effect of different scanning line spacing on the PV value is quantified and different types of surface microtextures on sapphire,including the squares,the rhombuses and the hexagons,are successfully fabricated,which can be applied in the friction reduction or anti-reflection field.展开更多
MoSi2 samples were prepared by a self-propagating high-temperature synthesis (SHS) and a hot-press technique. The sliding friction and wear properties of intermetallic MoSi2 against AISI10045 steel under dry friction ...MoSi2 samples were prepared by a self-propagating high-temperature synthesis (SHS) and a hot-press technique. The sliding friction and wear properties of intermetallic MoSi2 against AISI10045 steel under dry friction and oil lubrication conditions were investigated with a MRH-5A type ring-on-block friction and wear tester. The elemental composition, microstructure and worn surface morphology of the MoSi2 material were observed and analyzed by means of scanning electron microscopy (SEM) and X-ray diffraction (XRD). The synthetic parameter pv value reflecting friction work, was used to discuss the tribological properties of MoSi2 material. The results show that 1) oil lubrication can obviously improve the tribological properties of MoSi2, 2) the bigger the pv value, the greater the antifriction and the abrasive resistance of MoSi2 under oil lubrication, 3) with an increase in the pv value, the wear mechanism of MoSi2 material under dry sliding friction is the fatigue fracture and adhesive wear and 4) under oil lubrication the wear mechanism is mainly fatigue pitting.展开更多
Direct ink writing(DIW)is a widely adopted fabrication method for flexible functional materials.However,the structure formed through filament accumulation often exhibits unavoidable wave-textured patterns.Currently,li...Direct ink writing(DIW)is a widely adopted fabrication method for flexible functional materials.However,the structure formed through filament accumulation often exhibits unavoidable wave-textured patterns.Currently,limited literature focuses on the impact of texture structures in piezoelectric composite materials on the nanogenerator output performance.This study investigated the effect of surface wave-texture’s peak-to-valley(PV)value on piezoelectric output and proposed a surface PV value control method for DIW printing based on overlap rate.For piezoelectric composite materials,representative volume element(RVE)was employed to calculate the equivalent piezoelectric parameters of the composite material.The influence mechanism of the surface PV value on the nanogenerators’output performance was analyzed through simulation,elucidating the stress distribution and electric field intensity at different PV values.The findings reveal that as the PV value of the film surface increases from 14.29 to 80.86μm,the sensitivity of the composite material decreases from 0.832 to 0.723 V/N.Further investigation into the optimized nanogenerator demonstrated its capability to successfully detect finger-bending signals.Additionally,a machine learning model was developed to classify various human activities-including standing,non-strenuous exercise(walking),and strenuous exercise(running/jumping)-based on signals collected by the nanogenerator,achieving an impressive recognition accuracy of 97.89%.And the sensor was successfully applied in a badminton match for analysis.展开更多
基金supported by the National Natural Science Foundation of China(No.51805257)the China Postdoctoral Science Foundation(No.2019TQ0151)+3 种基金the National Natural Science Foundation of China for Creative Research Groups(No.51921003)the Foundation of Graduate Innovation Center in NUAA,China(No.KFJJ20190502)the Postgraduate Research&Practice Innovation Program of Jiangsu Province,China(No.KYCX19_0162)the Jiangsu Key Laboratory of Precision and Micro-Manufacturing Technology,China。
文摘Fabrication of the surface micro-texture on the C-plane sapphire is undertaken by a355 nm Ultraviolet(UV)pulsed laser.The surface micro-textures of sapphire with different laser scanning line spacing ranging from 10 lm to 100 lm are obtained,where the selection range of scanning line spacing is controlled in the range of the groove width and plasma width to obtain a surface of high Peak-Valley(PV)value.A reasonable processing order is proposed to manufacture different types of surface micro-textures on sapphire by laser ablation trajectory regulation.In the multiple-passes laser ablation of sapphire by the UV nanosecond pulsed laser,the scanning lines in each direction is treated as once scanning.On this basis,the multiple processing can be carried out to avoid the influence of the subsequent scanning on the machined groove.In addition,the effect of different scanning line spacing on the PV value is quantified and different types of surface microtextures on sapphire,including the squares,the rhombuses and the hexagons,are successfully fabricated,which can be applied in the friction reduction or anti-reflection field.
基金Projects 50405041 supported by National Natural Science Foundation of China and 04C218 by Hunan Province Education Foundation of China
文摘MoSi2 samples were prepared by a self-propagating high-temperature synthesis (SHS) and a hot-press technique. The sliding friction and wear properties of intermetallic MoSi2 against AISI10045 steel under dry friction and oil lubrication conditions were investigated with a MRH-5A type ring-on-block friction and wear tester. The elemental composition, microstructure and worn surface morphology of the MoSi2 material were observed and analyzed by means of scanning electron microscopy (SEM) and X-ray diffraction (XRD). The synthetic parameter pv value reflecting friction work, was used to discuss the tribological properties of MoSi2 material. The results show that 1) oil lubrication can obviously improve the tribological properties of MoSi2, 2) the bigger the pv value, the greater the antifriction and the abrasive resistance of MoSi2 under oil lubrication, 3) with an increase in the pv value, the wear mechanism of MoSi2 material under dry sliding friction is the fatigue fracture and adhesive wear and 4) under oil lubrication the wear mechanism is mainly fatigue pitting.
文摘Direct ink writing(DIW)is a widely adopted fabrication method for flexible functional materials.However,the structure formed through filament accumulation often exhibits unavoidable wave-textured patterns.Currently,limited literature focuses on the impact of texture structures in piezoelectric composite materials on the nanogenerator output performance.This study investigated the effect of surface wave-texture’s peak-to-valley(PV)value on piezoelectric output and proposed a surface PV value control method for DIW printing based on overlap rate.For piezoelectric composite materials,representative volume element(RVE)was employed to calculate the equivalent piezoelectric parameters of the composite material.The influence mechanism of the surface PV value on the nanogenerators’output performance was analyzed through simulation,elucidating the stress distribution and electric field intensity at different PV values.The findings reveal that as the PV value of the film surface increases from 14.29 to 80.86μm,the sensitivity of the composite material decreases from 0.832 to 0.723 V/N.Further investigation into the optimized nanogenerator demonstrated its capability to successfully detect finger-bending signals.Additionally,a machine learning model was developed to classify various human activities-including standing,non-strenuous exercise(walking),and strenuous exercise(running/jumping)-based on signals collected by the nanogenerator,achieving an impressive recognition accuracy of 97.89%.And the sensor was successfully applied in a badminton match for analysis.
