Chrome steels are used in bearings since they possess high strength and wear resistance.However,when those parts are in service,failure happens due to sliding friction before the lifetime.To improve the durability of ...Chrome steels are used in bearings since they possess high strength and wear resistance.However,when those parts are in service,failure happens due to sliding friction before the lifetime.To improve the durability of the American Iron and Steel Institute(AISI)52100 chromium steel,in this work,the effect of laser surface texturing(LST)was analyzed.With the different patterns of circle and ellipse comparing with the untextured samples,the wear behavior was investigated using the pin-on-disc tribometer.The lubricant used for wear analysis is semisolid lithium grease National Lubricating Grease Institute lubricant(SKF NLGI-3).Sliding wear analysis was conducted at different loads of 10 N,30 N and 50 N for the sliding speed of 750 r/min and 1400 r/min.The wear morphology was analyzed using a scanning electron microscope(SEM).The roughness of the samples was found using a white light interferometer.The effect of different patterns like circle and ellipse,alter the friction and wear properties of chromium alloy was observed compared with the untextured samples.LST shows considerable reduction in friction and wear for ellipsoidal pattern compared with the circular pattern because of wear debris and lubricant getting trapped.展开更多
Laser surface texturing is a versatile approach for manufacturing implants with suitable surfaces for os-seointegration.This work explores the use of laser to fabricate NiTi textured implants,testing two dif-ferent gr...Laser surface texturing is a versatile approach for manufacturing implants with suitable surfaces for os-seointegration.This work explores the use of laser to fabricate NiTi textured implants,testing two dif-ferent groove-based designs.Their performance was evaluated in vivo through implantation in Sprague Dawley rats’femur,being then analyzed after 4 and 12 weeks of implantation.Push-out experiments and histological characterization allowed to assess bone-implant bond and osseointegration and to compare the laser textured solutions with non-textured NiTi.Histology showed that,at 4 weeks of implantation,mainly immature woven bone was present whilst at 12 weeks a more mature bone had developed.Con-sidering the largest implantation time(12 weeks),results showed extraction forces considerably higher for textured implants(G2 and G3).Moreover,when comparing G2 and G3,it was found that G2(having the highest textured surface area)displayed the maximum extraction force among all groups,with an increase of 212%when compared to non-textured implants(G1).These results prove that the design and manufacturing technology are effective to promote an im-proved bone-implant bond,aiming the development of orthopedic implants.展开更多
While laser surface texturing(LST)is a promising manufacturing technique for surface functionalization,simultaneously realizing high precision and high efficiency in the LST of complex curved surface is challenging,du...While laser surface texturing(LST)is a promising manufacturing technique for surface functionalization,simultaneously realizing high precision and high efficiency in the LST of complex curved surface is challenging,due to continuously varied geometries of laser-matter incidence.In the present work,we propose a novel manufacturing system of 7-axis on-the-fly LST for complex curved surface,based on the integrated synchronization of 5-axis linkage motion platform with 2-axis galvanometer.Specifically,the algorithm for decomposing spatial texture trajectory on curved surface into low-frequency and high-frequency parts is established,based on which the kinematic model of synchronized 7-axis system is developed to derive the motion of each axis in both 5-axis linkage motion platform and 2-axis galvanometer simultaneously.Subsequently,the synchronized 7-axis LST system is experimentally realized,including the setup of mechanical stages integrated with optical path,the configuration of numerical control unit,and the development of processing software.Finally,case study of 7-axis on-the-fly LST of freeform aluminum surface is performed,and the advantages in terms of processing efficiency and texturing accuracy over 5-axis linkage LST are demonstrated.The correlation of reduced following errors between mechanical stages with the promoted performance of curved surface texturing by the 7-axis on-the-fly LST is further analyzed.Current work provides a feasible solution for establishing the manufacturing system for high performance LST of complex curved surface.展开更多
Shallow Hilbert curve patterns with easily programmable texture density were selected for laser texturing of stainless steel substrates.Two different texture path segment lengths(12 and 24 μm)and four different laser...Shallow Hilbert curve patterns with easily programmable texture density were selected for laser texturing of stainless steel substrates.Two different texture path segment lengths(12 and 24 μm)and four different laser power percentages(5%,10%,15%,and 20%)were investigated.The textured and smooth substrates were coated with thin polydopamine/polytetrafluoroethylene(PDA/PTFE)coatings for tribological property assessment.The effects of texture density(texture area coverage)and laser power on the durability and friction of the coated surfaces were studied.Laser texturing the substrates improved the coating durability up to 25 times,reduced the friction coefficient,and prevented coating global delamination.The textures fabricated with a laser power of 15%and a texture path segment length of 12 μm yielded the best coating durability.The textures provided the interlocking for the PTFE coating and thus prevented its global delamination.Furthermore,the PTFE inside the texture grooves replenished the solid lubricant worn away in the wear track and prolonged the coating wear life.展开更多
When the machine tool is in the start-and stop-stages,the stick-slip phenomenon will be observed and highprecision positioning,machining accuracy and fretting feed will not be guaranteed. The most critical reason is t...When the machine tool is in the start-and stop-stages,the stick-slip phenomenon will be observed and highprecision positioning,machining accuracy and fretting feed will not be guaranteed. The most critical reason is that there is the difference between the dynamic and the static friction coefficients. Textures with different area ratios are fabricated on the surfaces of the upper PTFE-based composite and the friction tests are carried out on a reciprocating tribotester under the boundary lubrication and flat-on-flat contact conditions. The results show that there exists an optimal textured area ratio of 19.6% that can minimize the difference between the dynamic and the static friction coefficients.展开更多
The combined use of focused ion beam(FIB)milling and field-emission scanning electron microscopy inspection(FESEM)is a unique and successful approach for assessment of near-surface phenomena at specific and selected l...The combined use of focused ion beam(FIB)milling and field-emission scanning electron microscopy inspection(FESEM)is a unique and successful approach for assessment of near-surface phenomena at specific and selected locations.In this study,a FIB/FESEM dual-beam platform was implemented to docment and analyze the wear micromechanisms on a laser-surface textured(LST)hardmetal(HM)tool.In particular,changes in surface and microstructural integrity of the laser-sculptured pyramids(effective cutting microfeatures)were characterized after testing the LST-HM tool against a steel workpiece in a workbench designed to simulate an external honing process.It was demonstrated that:(1)laser-surface texturing does not degrade the intrinsic surface integrity and tool effectiveness of HM pyramids;and(2)there exists a correlation between the wear and loading of shaped pyramids at the local level.Hence,the enhanced performance of the laser-textured tool should consider the pyramid geometry aspects rather than the microstructure assemblage of the HM grade used,at least for attempted abrasive applications.展开更多
This research aims to investigate the effect of pulsed Nd：YAG laser micro-welding on the microstructure,texture and magnetic properties of ultra-thin Fe-Co-7.15 wt%V magnetic alloy.Optical microscopy,scanning electro...This research aims to investigate the effect of pulsed Nd：YAG laser micro-welding on the microstructure,texture and magnetic properties of ultra-thin Fe-Co-7.15 wt%V magnetic alloy.Optical microscopy,scanning electron microscopy and electron backscattered diffraction techniques were used to study the microstructural evolutions.Also,vibrating sample magnetometry was used to characterize the magnetic properties.The results showed that the fractions of low Σ coincidence site lattice boundaries in the fusion zone are higher than those of the base metal.The welded samples experience a significant decrease in their magnetic properties.It was found that the formation of new fiber texture in the fusion zone and grain coarsening are the most important factors affecting the magnetic properties.展开更多
The friction behaviors of steel sheets at the corners of die and punch, under different conditions of surface textures (laser beam texture, shot blast texture), steel sheet rolling directions and lubricants, are studi...The friction behaviors of steel sheets at the corners of die and punch, under different conditions of surface textures (laser beam texture, shot blast texture), steel sheet rolling directions and lubricants, are studied by both SEM micro surface observations and friction coefficients measurement. The results show the friction coefficient at the corner of die is smaller than that at the corner of punch during stamping. The friction coefficient along rolling direction is lower than that along transverse direction, especially at the corner of punch. Differential initial surface texture has different sensitivity of friction coefficient to the lubricants. The sheet surface with laser beam texture (LBT) has shown a stronger adaptation to various lubricants than that with shot blast texture (SBT). After stamping, the surface with laser beam texture is still clear, the shot blast texture is indistinct.展开更多
The surface morphology of buffer layer yttrium-stabilized zirconia （YSZ） of YBa2CuaO7-σ （YBCO） high temperature superconducting films relies on a series of controllable experimental parameters. In this work, we f...The surface morphology of buffer layer yttrium-stabilized zirconia （YSZ） of YBa2CuaO7-σ （YBCO） high temperature superconducting films relies on a series of controllable experimental parameters. In this work, we focus on the influence of pulsed laser frequency and target crystalline type on surface morphology of YSZ films deposited by pulsed laser deposition （PLD） on rolling assisted biaxially textured substrate tapes. Usually two kinds of particles are observed in the YSZ layer： randomly distributed ones on the whole film and self-assembled ones along grain boundaries. SEM images are used to prove that particles can be partly removed when choosing dense targets of single crystalline. Lower frequency of pulsed laser also contributes to a smoother film surface. TEM images are used to view the crystalline structure of thin film. Thus we can obtain a basic understanding of how to prepare a particle-free YSZ buffer layer for YBCO in optimized conditions using PLD. The YBCO layer with nice structure and critical current density of around 5 MA/cm2 can be reached on smooth YSZ samples.展开更多
Textured Bi and MnBi/Bi thin films are prepared by the pulsed laser deposition method. The highly c-axis textured MnBi films are obtained by annealing the bilayer consisting of textured Bi and Mn films. The eoerciviti...Textured Bi and MnBi/Bi thin films are prepared by the pulsed laser deposition method. The highly c-axis textured MnBi films are obtained by annealing the bilayer consisting of textured Bi and Mn films. The eoercivities of the MnBi/Bi film are 1.5 T and 2.35 T at room temperature and at 373K, respectively, showing a positive temperature coefficient. Microstructural investigations show that the textured MnBi film results from the orientated growth induced by the textured Bi under-layer.展开更多
Medical stents are vital for treating vascular complications and restoring blood flow in millions of patients.Despite its widespread effectiveness,restenosis,driven by the complex interplay of cellular responses,remai...Medical stents are vital for treating vascular complications and restoring blood flow in millions of patients.Despite its widespread effectiveness,restenosis,driven by the complex interplay of cellular responses,remains a concern.This study investigated the reactions of vascular cells to nano/microscale wrinkle(nano-W and micro-W)patterns created on laser-textured nitinol(NiTi)surfaces by adjusting laser processing parameters,such as spot overlap ratio and line overlap ratio.Evaluation of topographical effects on endothelial and smooth muscle cells(SMCs)revealed diverse morphologies,proliferation rates,and gene expressions.Notably,microscale wrinkle patterns exhibited reduced monocyte adhesion and inflammation-related gene expression,demon-strating their potential applications in mitigating vascular complications after stent insertion.Additionally,an ex vivo metatarsal assay was utilized to bridge the gap between in vitro and in vivo studies,demonstrating enhanced angiogenesis on laser-textured NiTi surfaces.Laser-textured NiTi exhibits a guided formation process,empha-sizing their potential to promote swift endothelialization.These findings underscore the efficacy of laser texturing for tailored cellular interactions on metallic surfaces and offer valuable insights into optimizing biocompatibility and controlling cellular responses,which may pave the way for innovative advances in vascular care and contribute to the ongoing improvement of stent insertion.展开更多
Grid pattern was textured on Ti-6 Al-4 V alloy(TC4)substrate surface by nanosecond laser system.Laser joining of carbon fiber reinforced thermoplastic composite(CFRTP)to TC4 joints were performed,and the effect of tex...Grid pattern was textured on Ti-6 Al-4 V alloy(TC4)substrate surface by nanosecond laser system.Laser joining of carbon fiber reinforced thermoplastic composite(CFRTP)to TC4 joints were performed,and the effect of texture grid depth was investigated.The contact angle of molten CFRTP on textured TC4 surface was measured and the tensile-shear force was tested.The fracture surface and interface morphology were observed.The results indicated that the wettability of molten CFRTP on TC4 surface improved remarkably after laser textured TC4.Shear force of CFRTP/TC4 joints was increased by 156%after laser textured TC4 surface.When the depth of grid was deeper than 100μm,contact angle increased and incomplete filling of molten CFRTP in grid occurred,the shear force thus decreased gradually.Resin-carbon fibers mixture was adhered on the fracture surface of TC4,and the variation tendency of adhesion ratio was consistent with that of shear force.TC4 matrix was exfoliated from substrate and adhered at the fracture surface of CFRTP,indicating stronger mechanical interlocking occurred at the joining interface after laser textured TC4 surface.Beside mechanical interlocking,compound layer consisted of CTi_(0.42)V_(1.58)carburization phase was also confirmed at interface,suggesting that chemical bonding also occurred at the joining interface.展开更多
Laser multiple processing, i.e. laser surface texturing and then Laser Shock Processing (LSP), is a new surface processing technology for the preparation of bionic non-smooth surfaces. Based on engineering bionics, sa...Laser multiple processing, i.e. laser surface texturing and then Laser Shock Processing (LSP), is a new surface processing technology for the preparation of bionic non-smooth surfaces. Based on engineering bionics, samples of bionic non-smooth surfaces of stainless steel 0Crl 8Ni9 were manufactured in the form of reseau structure by laser multiple processing. The mechanical properties (including microhardness, residual stress, surface roughness) and microstructure of the samples treated by laser multiple processing were compared with those of the samples without LSP The results show that the mechanical properties of these samples by laser multiple processing were clearly improved in comparison with those of the samples without LSP The mechanisms underlying the improved surface microhardness and surface residual stress were analyzed, and the relations between hardness, comnressive residual stress and roughness were also presented.展开更多
The unsatisfactory corrosion properties of Mg-based alloys pose a significant obstacle to their widespread application. Plasma electrolytic oxidation(PEO) is a prevalent and effective coating method that produces a ce...The unsatisfactory corrosion properties of Mg-based alloys pose a significant obstacle to their widespread application. Plasma electrolytic oxidation(PEO) is a prevalent and effective coating method that produces a ceramic-like oxide coating on the surface of Mg-based alloys,enhancing their resistance to corrosion. Research has demonstrated that PEO treatment can substantially improve the corrosion performance of alloys based on magnesium in the short term. In an effort to enhance the corrosion resistance of PEO coatings over an extended period of time, researchers have turned their attention to the use of laser processes as both pre-and post-treatments in conjunction with the PEO process. Various laser processes, such as laser shock melting(LSM), laser shock adhesion(LSA), laser shock texturing(LST), and laser shock peening(LSP), have been investigated for their potential to improve PEO coatings on Mg substrates and their alloys. These laser melting processes can homogenize and alter the microstructure of Mg-based alloys while leaving the bulk material unchanged, thereby modifying the substrate surface. However, the porous and rough structure of PEO coatings, with their open and interconnected pore structure, can reduce their long-term corrosion resistance. As such, various laser processes are well-suited for surface modification of these coatings. This study will first examine the PEO process and the various types of laser processes used in this process, before investigating the corrosion behavior of PEO coatings in conjunction with laser pre-and post-treatment processes.展开更多
The cooperative effect of laser surface texturing(LST) and double glow plasma surface alloying on tribological performance of lubricated sliding contacts was investigated.A Nd:YAG laser was used to generate microdimpl...The cooperative effect of laser surface texturing(LST) and double glow plasma surface alloying on tribological performance of lubricated sliding contacts was investigated.A Nd:YAG laser was used to generate microdimples on steel surfaces. Dimples with the diameter of 150μm and the depth of 30-35μm distributed circumferentially on the disc surface.The alloying element Cr was sputtered to the laser texturing steel surface by double glow plasma technique.A deep diffusion layer with a thickness of 30μm and a high hardness of HV900 was formed in this alloy.Tribological experiments of three types of samples(smooth,texturing and texturing+alloying) were conducted with a ring-on-disc tribometer to simulate the face seal.It is found that,in comparison with smooth steel surfaces,the laser texturing samples significantly reduce the friction coefficient.Moreover,the lower wear rate of the sample treated with the two surface techniques is observed.展开更多
Zirconia(ZrO_2)incorporated ceramic coatings were fabricated on biodegradable ZM21 Mg alloy by the PEO coupled with EPD process.Subsequently,the sample surface was modified by laser texturing to improve the corrosion ...Zirconia(ZrO_2)incorporated ceramic coatings were fabricated on biodegradable ZM21 Mg alloy by the PEO coupled with EPD process.Subsequently,the sample surface was modified by laser texturing to improve the corrosion resistance,roughness and cell proliferation and growth properties.The corrosion performance of the fabricated samples along with the substrate was studied by electrochemical measurements under simulated body fluid(SBF)environment.The cell direct contact assay was conducted for the substrate and fabricated samples using L-929 mouse fibroblast cells for 24 h.The phase contrast images of cell direct contact assay revealed that fabricated samples exhibited better contact and response with the fibroblast cells,compared to the substrate.The addition of nanoparticles in the PEO process,called PEO coupled EPD process,resulted in attaining a higher thickness and improved corrosion performance of the samples than the PEO coated samples.Among all the samples,laser surface textured PEO,and PEO-EPD coated samples unveiled enhanced corrosion resistance,cell growth,thereby enabling it as a suitable prototype for biodegradable implant applications.展开更多
This study presents a comprehensive approach to applying texturing processes created by engraving on the surface of CoCr28Mo alloy workpieces using a 20 W pulsed nanosecond fiber laser.The hatch strategy and distance,...This study presents a comprehensive approach to applying texturing processes created by engraving on the surface of CoCr28Mo alloy workpieces using a 20 W pulsed nanosecond fiber laser.The hatch strategy and distance,frequency,and scan speed were control parameters for texturing applications.The effectiveness of the parameters in terms of roughness and contact angle of the texturized surface was investigated.Surface roughness and contact angle were analyzed using variance analysis to identify each variable's influence.It has been determined that the roughness of the texture defined by the hatch strategy plays a decisive role in the wettability behavior of the surface;however,the scan speed,frequency,and hatch distance which are among the laser surface texturing conditions are influential in the roughness and contact angle.Increasing scan speed and hatch distance while decreasing frequency resulted in smoother surfaces,increasing the contact angle.Textures having rough surfaces produced with different processing conditions exhibit a super hydrophilic behavior.The contact angle is most sensitive to the hatch distance;however,the frequency has the least influence on the contact angle.The most and least efficient surface roughness parameters are revealed to be scan speed and hatch distance,respectively.展开更多
Recently,various slippery liquid-infused porous surfaces(SLIPS)have been fabricated for the protection of various materials.However,these SLIPSs are limited by their underlying storage structure and superficial lubric...Recently,various slippery liquid-infused porous surfaces(SLIPS)have been fabricated for the protection of various materials.However,these SLIPSs are limited by their underlying storage structure and superficial lubricant layer,showing poor durability.Herein,inspired by the high-strength structure of Shell nacre’s“brick-mud”layer,we fabricated an all-inorganic composite coating by using wet chemically etched MXene as a brick and an aluminum phosphate binder(AP)as mud.Then,a series of microwell-array structures were designed and prepared on the coating via nanosecond ultrafast laser writing ablation technology.Subsequently,the textured surface was modified by a silane coupling agent.Vinyl-terminated polydimethylsiloxane(PDMS)was tightly grafted onto the porous surface through a thiol-ene click reaction to obtain lubricant grafted texture surface(LGTS).The prepared LGTS showed good lubrication properties for multiple phases,including various liquids,ice crystals,and solids.It exhibits excellent chemical stability and mechanical durability under deionized water impact,centrifugal test,strong acid solutions,anti/de-icing cycles,and high-intensity friction.Thus,the proposed strategy for constructing robust LGTS will greatly promote theoretical research on super wetting interfacial materials and their applications in the fields of antifouling,anti/de-icing,and lubricating protection.展开更多
Preferred surface integrity around the hole wall is one of the key parameters to ensure the optimized performance of hole components for nickel-based superalloy.The novel hole cold expansion technique introduced in th...Preferred surface integrity around the hole wall is one of the key parameters to ensure the optimized performance of hole components for nickel-based superalloy.The novel hole cold expansion technique introduced in this work involves the laser texturing process(LTP)followed by the Hertz contact rotary expansion process(HCREP),where the cylindrical sleeve is the critical component connecting the abovementioned two processes.The purpose of LTP is to obtain the most optimized strengthened cylindrical sleeve surface,preparing for the following HCREP.Hereafter,the HCREP acts on the nickel-based hole components by the rotary extruding movements of the strengthened sleeve and conical mandrel tools.As compared to the as-received GH4169 material,the surface integrity characterization for the strengthened hole shows that a plastic deformation layer with finer grains,higher micro-hardness,deeper compressive residual stress(CRS)distribution and lower surface roughness is formed at the hole wall.In addition,transmission electron microscope(TEM)observations reveal the microstructure evolution mechanism in the strengthened hole.Grain refinement near the hole wall is regarded as the fundamental reason for improving the surface integrity,where the aggregated dislocations and recombined dislocation walls can be clearly observed.展开更多
The effect of surface structure and coating on tribological properties of 45^# carbon steel disc was analyzed. A Nd：YAG laser was used to generate rnicrodirnples on steel surfaces. Dimples with diameter of 150 rn and...The effect of surface structure and coating on tribological properties of 45^# carbon steel disc was analyzed. A Nd：YAG laser was used to generate rnicrodirnples on steel surfaces. Dimples with diameter of 150 rn and depth of 50 rn were distributed in an orbicular array on disc surface. Then the alloying element Mo was sputtered to 45# carbon steel disc surface by means of double glow plasma technology. Diffusion Mo alloying layer with 30min thickness and high hardness up to 0.025 was formed on the disc surface. Tribological experiments of three types samples （smooth, texturing and texturing＋alloying） were conducted with a pin-on-disc tribometer. It is found that the dimpled-samples are most effective for reducing friction in comparison with smooth steel surthces, improving the lubricating state from boundary to hydrodynamic region.展开更多
文摘Chrome steels are used in bearings since they possess high strength and wear resistance.However,when those parts are in service,failure happens due to sliding friction before the lifetime.To improve the durability of the American Iron and Steel Institute(AISI)52100 chromium steel,in this work,the effect of laser surface texturing(LST)was analyzed.With the different patterns of circle and ellipse comparing with the untextured samples,the wear behavior was investigated using the pin-on-disc tribometer.The lubricant used for wear analysis is semisolid lithium grease National Lubricating Grease Institute lubricant(SKF NLGI-3).Sliding wear analysis was conducted at different loads of 10 N,30 N and 50 N for the sliding speed of 750 r/min and 1400 r/min.The wear morphology was analyzed using a scanning electron microscope(SEM).The roughness of the samples was found using a white light interferometer.The effect of different patterns like circle and ellipse,alter the friction and wear properties of chromium alloy was observed compared with the untextured samples.LST shows considerable reduction in friction and wear for ellipsoidal pattern compared with the circular pattern because of wear debris and lubricant getting trapped.
基金supported by FCT through the grants (No. SFRH/BD/140191/2018)the project No. PTDC/EME-EME/1442/2020 (Add2Mech Bio)+2 种基金by the project No. PTDC/EME-EME/30498/2017 (Fun Imp)also funded by National funds, through the Foundation for Science and Technology (FCT) (project Nos. UIDB/50026/2020 and UIDP/50026/2020)supported by FCT national funds, under the national support to R&D units grant, through the reference projects (Nos. UIDB/04436/2020 and UIDP/04436/2020)
文摘Laser surface texturing is a versatile approach for manufacturing implants with suitable surfaces for os-seointegration.This work explores the use of laser to fabricate NiTi textured implants,testing two dif-ferent groove-based designs.Their performance was evaluated in vivo through implantation in Sprague Dawley rats’femur,being then analyzed after 4 and 12 weeks of implantation.Push-out experiments and histological characterization allowed to assess bone-implant bond and osseointegration and to compare the laser textured solutions with non-textured NiTi.Histology showed that,at 4 weeks of implantation,mainly immature woven bone was present whilst at 12 weeks a more mature bone had developed.Con-sidering the largest implantation time(12 weeks),results showed extraction forces considerably higher for textured implants(G2 and G3).Moreover,when comparing G2 and G3,it was found that G2(having the highest textured surface area)displayed the maximum extraction force among all groups,with an increase of 212%when compared to non-textured implants(G1).These results prove that the design and manufacturing technology are effective to promote an im-proved bone-implant bond,aiming the development of orthopedic implants.
基金the support by the Harbin Manufacturing Science and Technology Innovation Talent Project(No.2023CXRCGD035)the Open Research Foundation of State Key Laboratory of Digital Manufacturing Equipment and Technology in Huazhong University of Science and Technology,China(No.IMETKF2023012).
文摘While laser surface texturing(LST)is a promising manufacturing technique for surface functionalization,simultaneously realizing high precision and high efficiency in the LST of complex curved surface is challenging,due to continuously varied geometries of laser-matter incidence.In the present work,we propose a novel manufacturing system of 7-axis on-the-fly LST for complex curved surface,based on the integrated synchronization of 5-axis linkage motion platform with 2-axis galvanometer.Specifically,the algorithm for decomposing spatial texture trajectory on curved surface into low-frequency and high-frequency parts is established,based on which the kinematic model of synchronized 7-axis system is developed to derive the motion of each axis in both 5-axis linkage motion platform and 2-axis galvanometer simultaneously.Subsequently,the synchronized 7-axis LST system is experimentally realized,including the setup of mechanical stages integrated with optical path,the configuration of numerical control unit,and the development of processing software.Finally,case study of 7-axis on-the-fly LST of freeform aluminum surface is performed,and the advantages in terms of processing efficiency and texturing accuracy over 5-axis linkage LST are demonstrated.The correlation of reduced following errors between mechanical stages with the promoted performance of curved surface texturing by the 7-axis on-the-fly LST is further analyzed.Current work provides a feasible solution for establishing the manufacturing system for high performance LST of complex curved surface.
基金supported by the National Science Foundation under Grants CMMI-1563227 and OIA-1457888。
文摘Shallow Hilbert curve patterns with easily programmable texture density were selected for laser texturing of stainless steel substrates.Two different texture path segment lengths(12 and 24 μm)and four different laser power percentages(5%,10%,15%,and 20%)were investigated.The textured and smooth substrates were coated with thin polydopamine/polytetrafluoroethylene(PDA/PTFE)coatings for tribological property assessment.The effects of texture density(texture area coverage)and laser power on the durability and friction of the coated surfaces were studied.Laser texturing the substrates improved the coating durability up to 25 times,reduced the friction coefficient,and prevented coating global delamination.The textures fabricated with a laser power of 15%and a texture path segment length of 12 μm yielded the best coating durability.The textures provided the interlocking for the PTFE coating and thus prevented its global delamination.Furthermore,the PTFE inside the texture grooves replenished the solid lubricant worn away in the wear track and prolonged the coating wear life.
基金financially supported by the National Natural Science Foundation of China (No. 51675268)
文摘When the machine tool is in the start-and stop-stages,the stick-slip phenomenon will be observed and highprecision positioning,machining accuracy and fretting feed will not be guaranteed. The most critical reason is that there is the difference between the dynamic and the static friction coefficients. Textures with different area ratios are fabricated on the surfaces of the upper PTFE-based composite and the friction tests are carried out on a reciprocating tribotester under the boundary lubrication and flat-on-flat contact conditions. The results show that there exists an optimal textured area ratio of 19.6% that can minimize the difference between the dynamic and the static friction coefficients.
基金supported by the German Research Foundation(DFG)within the Individual Research Grant(425923019)“Laser Surface Textured Cemented Carbides for Application in Abrasive Machining Processes”.
文摘The combined use of focused ion beam(FIB)milling and field-emission scanning electron microscopy inspection(FESEM)is a unique and successful approach for assessment of near-surface phenomena at specific and selected locations.In this study,a FIB/FESEM dual-beam platform was implemented to docment and analyze the wear micromechanisms on a laser-surface textured(LST)hardmetal(HM)tool.In particular,changes in surface and microstructural integrity of the laser-sculptured pyramids(effective cutting microfeatures)were characterized after testing the LST-HM tool against a steel workpiece in a workbench designed to simulate an external honing process.It was demonstrated that:(1)laser-surface texturing does not degrade the intrinsic surface integrity and tool effectiveness of HM pyramids;and(2)there exists a correlation between the wear and loading of shaped pyramids at the local level.Hence,the enhanced performance of the laser-textured tool should consider the pyramid geometry aspects rather than the microstructure assemblage of the HM grade used,at least for attempted abrasive applications.
文摘This research aims to investigate the effect of pulsed Nd：YAG laser micro-welding on the microstructure,texture and magnetic properties of ultra-thin Fe-Co-7.15 wt%V magnetic alloy.Optical microscopy,scanning electron microscopy and electron backscattered diffraction techniques were used to study the microstructural evolutions.Also,vibrating sample magnetometry was used to characterize the magnetic properties.The results showed that the fractions of low Σ coincidence site lattice boundaries in the fusion zone are higher than those of the base metal.The welded samples experience a significant decrease in their magnetic properties.It was found that the formation of new fiber texture in the fusion zone and grain coarsening are the most important factors affecting the magnetic properties.
文摘The friction behaviors of steel sheets at the corners of die and punch, under different conditions of surface textures (laser beam texture, shot blast texture), steel sheet rolling directions and lubricants, are studied by both SEM micro surface observations and friction coefficients measurement. The results show the friction coefficient at the corner of die is smaller than that at the corner of punch during stamping. The friction coefficient along rolling direction is lower than that along transverse direction, especially at the corner of punch. Differential initial surface texture has different sensitivity of friction coefficient to the lubricants. The sheet surface with laser beam texture (LBT) has shown a stronger adaptation to various lubricants than that with shot blast texture (SBT). After stamping, the surface with laser beam texture is still clear, the shot blast texture is indistinct.
基金Supported by the ITER Project of the Ministry of Science and Technology of China under Grant No 2011GB113004the Shanghai Commission of Science and Technology under Grant No 11DZ1100402the Youth Fund of the National Natural Science Foundation of China under Grant No 11204174
文摘The surface morphology of buffer layer yttrium-stabilized zirconia （YSZ） of YBa2CuaO7-σ （YBCO） high temperature superconducting films relies on a series of controllable experimental parameters. In this work, we focus on the influence of pulsed laser frequency and target crystalline type on surface morphology of YSZ films deposited by pulsed laser deposition （PLD） on rolling assisted biaxially textured substrate tapes. Usually two kinds of particles are observed in the YSZ layer： randomly distributed ones on the whole film and self-assembled ones along grain boundaries. SEM images are used to prove that particles can be partly removed when choosing dense targets of single crystalline. Lower frequency of pulsed laser also contributes to a smoother film surface. TEM images are used to view the crystalline structure of thin film. Thus we can obtain a basic understanding of how to prepare a particle-free YSZ buffer layer for YBCO in optimized conditions using PLD. The YBCO layer with nice structure and critical current density of around 5 MA/cm2 can be reached on smooth YSZ samples.
基金Supported by the National Natural Science Foundation of China under Grant Nos 51171001,51371009 and 50971003the Foundation of Key Laboratory of Neutron Physics of CAEP under Grant No 2014BB02
文摘Textured Bi and MnBi/Bi thin films are prepared by the pulsed laser deposition method. The highly c-axis textured MnBi films are obtained by annealing the bilayer consisting of textured Bi and Mn films. The eoercivities of the MnBi/Bi film are 1.5 T and 2.35 T at room temperature and at 373K, respectively, showing a positive temperature coefficient. Microstructural investigations show that the textured MnBi film results from the orientated growth induced by the textured Bi under-layer.
基金supported by a KIST project[2E32351,2E33122,2V09840-23-P023]the KU-KIST Graduate School of Converging Science and Technology Program+4 种基金supported by a National Research Foundation of Korea(NRF)grant funded by the Korean government(MSIT)[grant number RS-2023-00302145]supported by the Bio-cluster Industry Capacity Enhance-ment Project of Jeonbuk Technopark(JBTP)supported by the Korea Medical Device Development Fund grant funded by the Korean government(the Ministry of Science and ICT,the Ministry of Trade,Industry and Energy,the Ministry of Health&Wel-fare,and the Ministry of Food and Drug Safety)(NTIS Number:9991007189)supported by the Ministry of Trade,Industry,and Energy(MOTIE)of Korea through project No.P0022331supervised by the Korea Institute for Advance-ment of Technology(KIAT).
文摘Medical stents are vital for treating vascular complications and restoring blood flow in millions of patients.Despite its widespread effectiveness,restenosis,driven by the complex interplay of cellular responses,remains a concern.This study investigated the reactions of vascular cells to nano/microscale wrinkle(nano-W and micro-W)patterns created on laser-textured nitinol(NiTi)surfaces by adjusting laser processing parameters,such as spot overlap ratio and line overlap ratio.Evaluation of topographical effects on endothelial and smooth muscle cells(SMCs)revealed diverse morphologies,proliferation rates,and gene expressions.Notably,microscale wrinkle patterns exhibited reduced monocyte adhesion and inflammation-related gene expression,demon-strating their potential applications in mitigating vascular complications after stent insertion.Additionally,an ex vivo metatarsal assay was utilized to bridge the gap between in vitro and in vivo studies,demonstrating enhanced angiogenesis on laser-textured NiTi surfaces.Laser-textured NiTi exhibits a guided formation process,empha-sizing their potential to promote swift endothelialization.These findings underscore the efficacy of laser texturing for tailored cellular interactions on metallic surfaces and offer valuable insights into optimizing biocompatibility and controlling cellular responses,which may pave the way for innovative advances in vascular care and contribute to the ongoing improvement of stent insertion.
基金financially supported by National Natural Science Foundation of China(No.51875129)。
文摘Grid pattern was textured on Ti-6 Al-4 V alloy(TC4)substrate surface by nanosecond laser system.Laser joining of carbon fiber reinforced thermoplastic composite(CFRTP)to TC4 joints were performed,and the effect of texture grid depth was investigated.The contact angle of molten CFRTP on textured TC4 surface was measured and the tensile-shear force was tested.The fracture surface and interface morphology were observed.The results indicated that the wettability of molten CFRTP on TC4 surface improved remarkably after laser textured TC4.Shear force of CFRTP/TC4 joints was increased by 156%after laser textured TC4 surface.When the depth of grid was deeper than 100μm,contact angle increased and incomplete filling of molten CFRTP in grid occurred,the shear force thus decreased gradually.Resin-carbon fibers mixture was adhered on the fracture surface of TC4,and the variation tendency of adhesion ratio was consistent with that of shear force.TC4 matrix was exfoliated from substrate and adhered at the fracture surface of CFRTP,indicating stronger mechanical interlocking occurred at the joining interface after laser textured TC4 surface.Beside mechanical interlocking,compound layer consisted of CTi_(0.42)V_(1.58)carburization phase was also confirmed at interface,suggesting that chemical bonding also occurred at the joining interface.
基金supported by the National Natural Science Foundation of China (Grant No.50705038,50735001 and 10804037)the Foundation of Jiangsu Province (Grant No.06-D-023,BK2007512 and BG2007033)+2 种基金The 8th Student Research Train Program of Jiangsu University (Grant No.08A172)the Innovation Program of Graduated Student of Jiangsu Province (Grant No.XM2006-45)the Open Foundation of Jiangsu Key Laboratory of Advanced Numerical Control Technology (Grant No.KXJ07126)
文摘Laser multiple processing, i.e. laser surface texturing and then Laser Shock Processing (LSP), is a new surface processing technology for the preparation of bionic non-smooth surfaces. Based on engineering bionics, samples of bionic non-smooth surfaces of stainless steel 0Crl 8Ni9 were manufactured in the form of reseau structure by laser multiple processing. The mechanical properties (including microhardness, residual stress, surface roughness) and microstructure of the samples treated by laser multiple processing were compared with those of the samples without LSP The results show that the mechanical properties of these samples by laser multiple processing were clearly improved in comparison with those of the samples without LSP The mechanisms underlying the improved surface microhardness and surface residual stress were analyzed, and the relations between hardness, comnressive residual stress and roughness were also presented.
文摘The unsatisfactory corrosion properties of Mg-based alloys pose a significant obstacle to their widespread application. Plasma electrolytic oxidation(PEO) is a prevalent and effective coating method that produces a ceramic-like oxide coating on the surface of Mg-based alloys,enhancing their resistance to corrosion. Research has demonstrated that PEO treatment can substantially improve the corrosion performance of alloys based on magnesium in the short term. In an effort to enhance the corrosion resistance of PEO coatings over an extended period of time, researchers have turned their attention to the use of laser processes as both pre-and post-treatments in conjunction with the PEO process. Various laser processes, such as laser shock melting(LSM), laser shock adhesion(LSA), laser shock texturing(LST), and laser shock peening(LSP), have been investigated for their potential to improve PEO coatings on Mg substrates and their alloys. These laser melting processes can homogenize and alter the microstructure of Mg-based alloys while leaving the bulk material unchanged, thereby modifying the substrate surface. However, the porous and rough structure of PEO coatings, with their open and interconnected pore structure, can reduce their long-term corrosion resistance. As such, various laser processes are well-suited for surface modification of these coatings. This study will first examine the PEO process and the various types of laser processes used in this process, before investigating the corrosion behavior of PEO coatings in conjunction with laser pre-and post-treatment processes.
基金Project(2007046) supported by High Technology Research Project of Jiangsu Province,China
文摘The cooperative effect of laser surface texturing(LST) and double glow plasma surface alloying on tribological performance of lubricated sliding contacts was investigated.A Nd:YAG laser was used to generate microdimples on steel surfaces. Dimples with the diameter of 150μm and the depth of 30-35μm distributed circumferentially on the disc surface.The alloying element Cr was sputtered to the laser texturing steel surface by double glow plasma technique.A deep diffusion layer with a thickness of 30μm and a high hardness of HV900 was formed in this alloy.Tribological experiments of three types of samples(smooth,texturing and texturing+alloying) were conducted with a ring-on-disc tribometer to simulate the face seal.It is found that,in comparison with smooth steel surfaces,the laser texturing samples significantly reduce the friction coefficient.Moreover,the lower wear rate of the sample treated with the two surface techniques is observed.
基金the grants received from the Science and Engineering Research Board(SERB),New Delhi(SR/S3/ME/0024/2011,dated 3rd July 2012)。
文摘Zirconia(ZrO_2)incorporated ceramic coatings were fabricated on biodegradable ZM21 Mg alloy by the PEO coupled with EPD process.Subsequently,the sample surface was modified by laser texturing to improve the corrosion resistance,roughness and cell proliferation and growth properties.The corrosion performance of the fabricated samples along with the substrate was studied by electrochemical measurements under simulated body fluid(SBF)environment.The cell direct contact assay was conducted for the substrate and fabricated samples using L-929 mouse fibroblast cells for 24 h.The phase contrast images of cell direct contact assay revealed that fabricated samples exhibited better contact and response with the fibroblast cells,compared to the substrate.The addition of nanoparticles in the PEO process,called PEO coupled EPD process,resulted in attaining a higher thickness and improved corrosion performance of the samples than the PEO coated samples.Among all the samples,laser surface textured PEO,and PEO-EPD coated samples unveiled enhanced corrosion resistance,cell growth,thereby enabling it as a suitable prototype for biodegradable implant applications.
基金supported by Dokuz Eylul University under project no.2021.KB.FEN.043.
文摘This study presents a comprehensive approach to applying texturing processes created by engraving on the surface of CoCr28Mo alloy workpieces using a 20 W pulsed nanosecond fiber laser.The hatch strategy and distance,frequency,and scan speed were control parameters for texturing applications.The effectiveness of the parameters in terms of roughness and contact angle of the texturized surface was investigated.Surface roughness and contact angle were analyzed using variance analysis to identify each variable's influence.It has been determined that the roughness of the texture defined by the hatch strategy plays a decisive role in the wettability behavior of the surface;however,the scan speed,frequency,and hatch distance which are among the laser surface texturing conditions are influential in the roughness and contact angle.Increasing scan speed and hatch distance while decreasing frequency resulted in smoother surfaces,increasing the contact angle.Textures having rough surfaces produced with different processing conditions exhibit a super hydrophilic behavior.The contact angle is most sensitive to the hatch distance;however,the frequency has the least influence on the contact angle.The most and least efficient surface roughness parameters are revealed to be scan speed and hatch distance,respectively.
基金supported by the National Natural Science Foundation of China(No.52205313)Natural Science Foundation of Shandong Province(ZR2022QE161),China Postdoctoral Science Foundation(2023M734093)+1 种基金the Tribology Science Fund of State Key Laboratory of Solid Lubrication(LSL-2312)Scientific Innovation Project for Young Scientists in Shandong Provincial Universities(2023KJ145,2023KJ148).
文摘Recently,various slippery liquid-infused porous surfaces(SLIPS)have been fabricated for the protection of various materials.However,these SLIPSs are limited by their underlying storage structure and superficial lubricant layer,showing poor durability.Herein,inspired by the high-strength structure of Shell nacre’s“brick-mud”layer,we fabricated an all-inorganic composite coating by using wet chemically etched MXene as a brick and an aluminum phosphate binder(AP)as mud.Then,a series of microwell-array structures were designed and prepared on the coating via nanosecond ultrafast laser writing ablation technology.Subsequently,the textured surface was modified by a silane coupling agent.Vinyl-terminated polydimethylsiloxane(PDMS)was tightly grafted onto the porous surface through a thiol-ene click reaction to obtain lubricant grafted texture surface(LGTS).The prepared LGTS showed good lubrication properties for multiple phases,including various liquids,ice crystals,and solids.It exhibits excellent chemical stability and mechanical durability under deionized water impact,centrifugal test,strong acid solutions,anti/de-icing cycles,and high-intensity friction.Thus,the proposed strategy for constructing robust LGTS will greatly promote theoretical research on super wetting interfacial materials and their applications in the fields of antifouling,anti/de-icing,and lubricating protection.
基金sponsored by the National Key Research and Development Program of China(2018YFC1902404)the National Natural Science Foundation of China(51725503,51705155)Innovation Program of Shanghai Municipal Education Commission(2019-01-07-00-02-E00068)。
文摘Preferred surface integrity around the hole wall is one of the key parameters to ensure the optimized performance of hole components for nickel-based superalloy.The novel hole cold expansion technique introduced in this work involves the laser texturing process(LTP)followed by the Hertz contact rotary expansion process(HCREP),where the cylindrical sleeve is the critical component connecting the abovementioned two processes.The purpose of LTP is to obtain the most optimized strengthened cylindrical sleeve surface,preparing for the following HCREP.Hereafter,the HCREP acts on the nickel-based hole components by the rotary extruding movements of the strengthened sleeve and conical mandrel tools.As compared to the as-received GH4169 material,the surface integrity characterization for the strengthened hole shows that a plastic deformation layer with finer grains,higher micro-hardness,deeper compressive residual stress(CRS)distribution and lower surface roughness is formed at the hole wall.In addition,transmission electron microscope(TEM)observations reveal the microstructure evolution mechanism in the strengthened hole.Grain refinement near the hole wall is regarded as the fundamental reason for improving the surface integrity,where the aggregated dislocations and recombined dislocation walls can be clearly observed.
基金Funded by the High Technology Research Project of Jiangsu Province (No. BG2007046)the Productive Translation Item of College Scientific Research of Jiangsu Province Educational Office( No. JHB06-04)
文摘The effect of surface structure and coating on tribological properties of 45^# carbon steel disc was analyzed. A Nd：YAG laser was used to generate rnicrodirnples on steel surfaces. Dimples with diameter of 150 rn and depth of 50 rn were distributed in an orbicular array on disc surface. Then the alloying element Mo was sputtered to 45# carbon steel disc surface by means of double glow plasma technology. Diffusion Mo alloying layer with 30min thickness and high hardness up to 0.025 was formed on the disc surface. Tribological experiments of three types samples （smooth, texturing and texturing＋alloying） were conducted with a pin-on-disc tribometer. It is found that the dimpled-samples are most effective for reducing friction in comparison with smooth steel surthces, improving the lubricating state from boundary to hydrodynamic region.
