Copper metal is widely electroplated for microelectronic interconnections such as redistribution layers(RDL),pillar bumps,through silicon vias,etc.With advances of multilayered RDL,via-on-via structures have been deve...Copper metal is widely electroplated for microelectronic interconnections such as redistribution layers(RDL),pillar bumps,through silicon vias,etc.With advances of multilayered RDL,via-on-via structures have been developed for ultrahigh-density any-layer interconnection,which expects superconformal filling of interlayer low aspect-ratio vias jointly with coplanar lines and pads.However,it poses a great challenge to electrodeposition,because current via fill mechanisms are stemming from middle to high aspect-ratio(>0.8)vias and lacking applicability in low aspect-ratio(<0.3)RDL-vias,where via geometry related electric-flow fields coupling must be reconsidered.In the present work,a four-additive strategy has been developed for RDL-vias fill and thoroughly investigated from additive electrochemistry,in situ Raman spectroelectrochemistry,and quantum chemistry perspectives.A novel adsorbate configuration controlled(ACC)electrodeposition mechanism is established that at weak-convection bilateral edges and lower corners,the adsorbate displays a weakly-adsorbing configuration to assist accelerator-governed deposition,whereas at strong-convection center,the adsorbate exhibits a mildlyadsorbing configuration to promote leveler-determined inhibition.Deposit profiles can be tailored from dished,flat to domed,depending on predominance of leveler over accelerator.This study should lay theoretical and practical foundations in design and application of copper electroplating additives of multiple adsorbate configurations to cope with complicated interconnect scenarios.展开更多
This paper evaluates the performance of creep feed grindingγ-TiAl intermetallic(Ti-45 Al-2 Mn-2 Nb)using electroplated diamond wheels.Firstly,a comparative analysis with the grinding results by using electroplated CB...This paper evaluates the performance of creep feed grindingγ-TiAl intermetallic(Ti-45 Al-2 Mn-2 Nb)using electroplated diamond wheels.Firstly,a comparative analysis with the grinding results by using electroplated CBN wheels was conducted,mainly involving abrasive wheel wear behavior and maximum material removal rate below surface burn limit.It was found that the diamond wheel would produce much better grinding results including lower wheel wear rate and higher maximum material removal rate.Then the surface integrity obtained at different level of material removal rate was characterized with the utilization of the diamond wheel.The poor ductility of thisγ-TiAl intermetallic material was found to have a marginal effect on the surface integrity,as no severe surface defects such as material pullout were generated during the stable wheel wear stage.For the involved operating parameters,a deformation layer was produced with~10μm or more in thickness depending on the material removal rate used.Meanwhile,a work-hardened layer extending to more than 100μm was produced with a maximum microhardness of above 520 HV0.05(bulk value 360 HV0.05).The residual stress remained compressive,with a value of above-100 MPa and even up to-500 MPa for an elevated material removal rate.Shearing chip was the main chip type,indicating good wheel sharpness in the grinding process.展开更多
Mechanical properties of structural materials are particularly important for design, performance realization and reliability analysis of microelectromechanical systems （MEMS）. Furthermore, accurate database of mecha...Mechanical properties of structural materials are particularly important for design, performance realization and reliability analysis of microelectromechanical systems （MEMS）. Furthermore, accurate database of mechanical properties at the micro scale can provide indispensable reference for establishing MEMS standard. Electroplated nickel film is one of the most favored structural materials used in MEMS, thus its mechanical properties has been studied for many years. However, the measured values show large scatter in Yotmg＇s modulus of nickel film. Young＇s modulus and yield stress of electroplated nickel film are measured by using a micro-tensile testing instrument. The tensile load applied on the specimen is measured by a load cell with accuracy 0.25 mN directly, without additional friction. Through measuring the axial stiffness coefficient of the tensile instnunent in situ, the tensile strain of the specimen is obtained by using two-serial spring model. The electroplated nickel films were fabricated from sulfarnate baths, and the gauge section is 500μm long and 10μm wide nominally, and thickness range between 25 μm and 50μm. The obtained Young＇s modulus from tensile testing is 83＋6 GPa for nickel specimens electroplated at current density of 20 mA/cm2 and it increases to 124＋5 GPa as current density is decreased to 10 mA/cm2. The phenomena are interpreted in terms of porosity of microstructure. The higher current density produced rnicrostucture with low density and high volume fraction of pores, and the microstructure of high porosity corresponds to a lower modulus. The measured values of Young＇s modulus are consistent with those of calculated from the exponential empirical formula between Young＇s modulus and porosity. The micro-tensile testing instrument can also be used for mechanical measurement of other MEMS films.展开更多
Galvanic corrosion behavior of Ti-1023 titanium alloy coupled 30CrMnSiA steel was investigated in 3.5% NaCl solution. Particular attention was given to the effect of three different electroplated coatings on corrosion...Galvanic corrosion behavior of Ti-1023 titanium alloy coupled 30CrMnSiA steel was investigated in 3.5% NaCl solution. Particular attention was given to the effect of three different electroplated coatings on corrosion behavior of the galvanic couple. Galvanic corrosion test was conducted on Ti-1023 titanium alloy which coupled Ni-electroplated 30CrMnSiA, Zn-electroplated 30CrMnSiA, Cd-electroplated 30CrMnSiA and bare 30CrMnSiA, respectively. Corrosion properties including open circuit potential （Eoc）, galvanic corrosion potential （Eg）, and galvanic corrosion current （lg） were monitored. Corrosion morphology was observed by optical microscope （OM） and corrosion mechanism was analyzed and discussed. The results show that the three electroplated coatings improve the corrosion resistance of the anode in different magnitudes. Ni-electroplated 30CrMnSiA and Cd-electroplated 30CrMnSiA coatings are found to be least susceptible to galvanic corrosion when coupled Ti-1023 titanium alloy. Zn-electroplated 30CrMnSiA is moderately susceptible to galvanic corrosion. But the bare 30CrMnSiA is highly susceptible to galvanic corrosion in corrosive environment.展开更多
To improve the bonding strength between the nickel bond and the hub of the electroplated diamond grinding wheel,a hybrid technique was proposed to combine laser prequenching steel substrate and post-electroplating nic...To improve the bonding strength between the nickel bond and the hub of the electroplated diamond grinding wheel,a hybrid technique was proposed to combine laser prequenching steel substrate and post-electroplating nickel.To validate the effectiveness of the proposed technique,AISI 1045 substrate was nickel-coated.The bonding properties between the electroplated nickel coating and substrate with or without laser-discrete-quenching were discussed comparatively by scratch,indentation,and thermal shock tests.The results show that the prequenching treatment leads to phase transformation of AISI 1045 microstructure from the mixed pearlite and ferrite phases into the martensitic phase.Since the martensitic phase is characterized as a high corrosion resistance,the interface of substrate/coating is smooth and flat in the prequenched zone,and the coating is bonded well with the steel substrate.In contrast to the steel substrate without pre-quenching treatment,the proposed technique significantly enhanced the bonding strengths of the electroplated nickel-coating.On one hand,the average hardness of electroplated nickel-coating on the laser pre-quenched zone is increased by 18.7%,and the scratch depth with the same load become narrower and shallower.On the other hand,the coefficient of friction(CoF)and the vibration amplitude are reduced,and the coating is bonded effectively with the substrate to inhibit the crack initialization at the interface.This prevents effectively the coating from peeling off and improves significantly the thermal shock resistance property.展开更多
Cracks may easily occur in the fusion weld between vanadium alloys and stainless steel due to the brittle intermetallics and welding stress. The high vacuum electron beam braze-welding has been successfully used to jo...Cracks may easily occur in the fusion weld between vanadium alloys and stainless steel due to the brittle intermetallics and welding stress. The high vacuum electron beam braze-welding has been successfully used to join vanadium alloy（V-5Cr-STi） to stainless steel （HR-2） with electroplated Cu and Ag coating. To investigate the effects of electroplated coating on the weldability, the joint appearaace, the microstrueture and the mechanical properties of the joints have been thoroughly analyzed. The results show that the joint surface configuration was good and root reinforcement was full and smooth. A reaction zone （RZ） was gained on the interface between the V-5 Cr-5 Ti alloy and HR-2 stainless steel base metals. The width of reaction zone at the top of the joint was up to O. 65 mm, wider than that in the bottom of the joint （ 0.46 mm）. The reaction zone consisted of considerably smaller dendritic structures with an average grain size of less than 10μm. Element Ag and Cu almost enriched the interface between V-SCr-5Ti alloy substrate and RZ, serving as a physical barrier which decreases or avoids the formation of intermetallics. The maximum tensile strength of vanadium alloy^stainless steel dissimilar alloy joint was more than 300 MPa. The joint was defects free.展开更多
The ability to predict a grinding force is important to control,monitor,and optimize the grinding process.Few theoretical models were developed to predict grinding forces when a structured wheel was used in a grinding...The ability to predict a grinding force is important to control,monitor,and optimize the grinding process.Few theoretical models were developed to predict grinding forces when a structured wheel was used in a grinding process.This paper aimed to establish a single-grit cutting force model to predict the ploughing,friction and cutting forces in a grinding process.It took into the consideration of actual topography of the grinding wheel,and a theoretical grinding force model for grinding hardened AISI 52100 by the wheel with orderly-micro-grooves was proposed.The model was innovative in the sense that it represented the random thickness of undeformed chips by a probabilistic expression,and it reflected the microstructure characteristics of the structured wheel explicitly.Note that the microstructure depended on the randomness of the protruding heights and distribution density of the grits over the wheel.The proposed force prediction model was validated by surface grinding experiments,and the results showed(1)a good agreement of the predicted and measured forces and(2)a good agreement of the changes of the grinding forces along with the changes of grinding parameters in the prediction model and experiments.This research proposed a theoretical grinding force model of an electroplated grinding wheel with orderly-micro-grooves which is accurate,reliable and effective in predicting grinding forces.展开更多
Ni coating was deposited on carbon steel by a mechanical attrition enhanced electroplating （MAEE） process. During the electroplating, the mechanical attrition（MA） was introduced by impact of glass balls on the sam...Ni coating was deposited on carbon steel by a mechanical attrition enhanced electroplating （MAEE） process. During the electroplating, the mechanical attrition（MA） was introduced by impact of glass balls on the sample surface with a special vibrating frequency. The surface and cross-sectional images of Ni coating were observed with SEM. The microstructure and crystallinity of coating were examined with TEM and XRD. The electrochemical performance of coating was measured with polarization curves and electrochemical impedance spectroscopy （EIS） and its mechanical behaviours, such as tensile strength and hardness, were studied. The results show that the MA has significant effects on the microstructure and property of the electroplated Ni coating. By MA, the coating becomes smooth, compact, thin and has refined grains and is free of cracks and pores. Consequently, the adhesion, tensile strength, hardness and corrosion resistance of coating are improved significantly.展开更多
Monolayered Co and trilayered Co/Cu/Co were electroplated on 485 μm-diameter Cu wires using the bath pH 2.5. These wires can be functioned as magnetic sensors owing to their magnetoimpedance （MI） effect. By measuri...Monolayered Co and trilayered Co/Cu/Co were electroplated on 485 μm-diameter Cu wires using the bath pH 2.5. These wires can be functioned as magnetic sensors owing to their magnetoimpedance （MI） effect. By measuring at four different frequencies （100, 250, 500, and 1000 kHz） and Co thicknesses （2.5, 5.0, 10.0, and 25.0μm）, the MI ratio of electroplated Co on Cu wires tended to increase with increasing Co thickness and frequency of the driving current. The Co/Cu/Co on Cu wires exhibited even higher MI ratio. The magnetic layer also regulated the magnetic inductions and anisotropy regardless of the size of nonmagnetic core. Nevertheless, the diameter of the Cu core had a significant effect on the MI ratio. By comparing with the 47.7 μm-diameter Ag cores electroplated by Co and Co/Cu/Co of the same thickness, the Cu cores with a larger diameter gave rise to a larger MI ratio because their lower electrical resistance enhanced the crossing effect. Substantial MI ratio was observed even in a low frequency regime because the skin effect occurred at a low frequency in the case of electroplated wires with large core diameters.展开更多
Ferromagnetic resonance （FMR）, Ferromagnetic antirresonance （FMAR） and low field magnetoimpedance （MI） are the characteristic features of high frequency losses in applied fields. While some results on FMR and FM...Ferromagnetic resonance （FMR）, Ferromagnetic antirresonance （FMAR） and low field magnetoimpedance （MI） are the characteristic features of high frequency losses in applied fields. While some results on FMR and FMAR in CoFeNi electroplated wires were reported earlier, here we present microwave absorption in CuBe wires electroplated by 1 μm FeCoNi magnetic layer at very low fields. These data are comparatively analysed together with longitudinal hysteresis loops in order to reveal the correlation between power absorption and magnetization processes. Microwave studies are made by using the cavity perturbation method at 9.65 GHz for a DC field parallel to the sample axis, and with microwave magnetic field hrf parallel or perpendicular to the wire axis. Two peaks have been observed in all samples, one is due to FMR, and the other is, at very low fields, related to MI. The MI peaks represent minima in power absorption. By comparing with the hysteresis loop we remark the close correspondence between the MI phenomena in the axial mode and the concomitant magnetization process.展开更多
In order to develop the high-efficiency and precision machining technique of TiCp/Ti - 6Al-4V particulate reinforced titanium matrix composites （PTMCs）, high-speed grinding experiments were conducted using the singl...In order to develop the high-efficiency and precision machining technique of TiCp/Ti - 6Al-4V particulate reinforced titanium matrix composites （PTMCs）, high-speed grinding experiments were conducted using the single-layer electroplated cubic boron nitride （CBN） wheel and brazed CBN wheel, respectively. The comparative grinding performance was studied in terms of grinding force, grinding temperature, grinding-induced surface features and defects. The results display that the grinding forces and grinding temperature obtained with the brazed CBN wheel are always lower than those with the electroplated CBN wheel. Though the voids and microcracks are the dominant grinding-induced surface defects, the brazed CBN wheel produces less surface defects compared to the electroplated wheel according to the statistical analysis results. The max mum materials removal rate with the brazed CBN wheel is much higher than that with the electroplated one. All above indicate that the single-layer brazed CBN super-abrasive wheel is more suitable for high-speed grinding of PTMCs than the electroplated counterpart.展开更多
The cutting process of electroplated diamond wire saw was researched on the basis of impulse and vibration machining theories. The different contact states in the cutting process were analyzed by using the finite elem...The cutting process of electroplated diamond wire saw was researched on the basis of impulse and vibration machining theories. The different contact states in the cutting process were analyzed by using the finite element method. It shows that the cutting stress is uniformly distributed along the direction of the workpiece width in the steady state. A mathematical equation of sawing trajectory was established by using the superposition principle and the cutting experiment of wire saw to calculate the cutting trajectory. The comparison of the theoretical trajectory with the calculated one indicates that the error is less than 15%. The research results provide a theoretic basis for optimization of the saw's cutting process parameters.展开更多
Electroplating has been used to produce Cu-Bi coatings. The crystal structure and lattice parameters of Cu in Cu-Bi composite coating were measured and compared with Cu coating. The mechanical properties of the coatin...Electroplating has been used to produce Cu-Bi coatings. The crystal structure and lattice parameters of Cu in Cu-Bi composite coating were measured and compared with Cu coating. The mechanical properties of the coatings were also studied. It was found that the deposition parameters have significant effect on the mechanical properties of the Cu-Bi coatings. The microhardness has been improved from HVso165 of Cu coating to HVs0 250 of Cu-Bi composite coating prepared at 50 mA/cm2 for 20 min. Correspondingly, wear resistance of the Cu-Bi composite coating has also been enhanced significantly.展开更多
Cu/Al laminar composite was prepared by dipping Zn layer and then electroplating Cu thick layer on pure Al sheet.During annealing the Cu/Al composites at temperature from 473 to 673 K, the Cu/Al interfacial diffusion ...Cu/Al laminar composite was prepared by dipping Zn layer and then electroplating Cu thick layer on pure Al sheet.During annealing the Cu/Al composites at temperature from 473 to 673 K, the Cu/Al interfacial diffusion and reaction and itskinetics and also the electrical resistivity of the composites were studied. The results show that no Cu?Al IMC layer is observable asthe composites are annealed at 473 K for time till 360 h, indicating that the Zn intermediate layer can effectively suppress the Cu/Alinterfacial diffusion. However, as the composites are annealed at 573 K and above, Zn atoms in the Zn layer dissolve into the Culayer. Tri-layered reaction product of CuAl2/CuAl/Cu9Al4 then forms from the Al side to the Cu side. The IMC layer follows thediffusion-controlled growth kinetics. Electrical resistivity of the Cu/Al composites increases with the increase of the annealingtemperature and time.展开更多
Resulting from the rising levels of atmospheric carbon, ocean acidification has become a global problem. It has significant impacts on the development, survival, growth and physiology of marine organisms. Therefore, a...Resulting from the rising levels of atmospheric carbon, ocean acidification has become a global problem. It has significant impacts on the development, survival, growth and physiology of marine organisms. Therefore, a high- precision sensor is urgently needed to measure the pH of sea-water. Iridium wire with a diameter of 0.25 mm is used as the substrate, and an Ir/Ir（OH）x pH electrode is prepared by a one-step electrochemical method in a LiOH solution at the room temperature. A scanning electron microscope （SEM） observation reveals that it is coated with nanoscale particles. In laboratory tests, the electrode exhibits a very promising pH response, with an ideal Nernst slope （56.14-59.52）, fast response, good stability and long fife-span in tested pH buffer solutions. For a sea trial, four pH electrodes and one Ag/AgC1 reference electrode are integrated with a self-made chemical sensor, and a profile detection of nearly 70 m is implemented near Newport Harbor, California on August 3, 2015. The results reflect that the pH value measured by the sensor is very close to the data given by Sea-Bird 911 plus CTD, with a difference value ranging from 0.000 075 to 0.064 719. And the sensor shows a better data matching degree in 0-40 m water depth. In addition, the high precision and accuracy of the sensor make it possible to use in the ocean observation field.展开更多
Ni-P-SiC composite coatings were electroplated on carbon steel substrate assisted by mechanical attrition （MA）. The MA action was conducted by dispersing glass balls on the cathodic surface, vibrating in the horizon...Ni-P-SiC composite coatings were electroplated on carbon steel substrate assisted by mechanical attrition （MA）. The MA action was conducted by dispersing glass balls on the cathodic surface, vibrating in the horizontal direction. The experimental results show that, under the assistant of MA action, the adhesion of Ni-P-SiC coating on the steel substrate can be improved effectively, and the Ni-P-SiC coatings exhibit a crystallized structure and Ni-P matrix can combine tightly with SiC particles, and the hardness and corrosion resistance of these coatings increase markedly. During heat treatment, the defects produced in conventional Ni-P-SiC composite coatings can be avoided assisted by MA action. Both of the wear of these coatings can be improved further.展开更多
Graphite flake/Cu composite has attracted tremendous attention as a promising heat sinks materials owing to its easy machinability and superior thermal properties. However, its preparation process still faces several ...Graphite flake/Cu composite has attracted tremendous attention as a promising heat sinks materials owing to its easy machinability and superior thermal properties. However, its preparation process still faces several technological limitations including complex, time-consuming and costly synthetic approaches. In this work, a facile and scalable intermittently electroplated method is applied to prepare Cu-coated graphite flake composite powders, which are subsequently sintered into dense composite bulks. The results show that the graphite flake is successfully coated with a uniform and compact Cu shell,which effectively inhibits the segregation accumulation of graphite flakes and contributes to homogeneous distribution of graphite in the sintered graphite flake/Cu composites. The as-sintered composites exhibit an excellent thermal conductivity of 710 W·m-1·K-1and an outstanding bending strength of 93 MPa. Such performance, together with the simple, efficient powder-preparation process, suggests that the present strategy may open up opportunities for the development of thermal management materials.展开更多
Baded on the study of nickel electroplating technology at room temperature, the plated sheet containing rapidly solidified Al-Fe-Cu- V-Si-Ni-Ce-Zr aluminum alloy powders is constructed successfully. The powders and ni...Baded on the study of nickel electroplating technology at room temperature, the plated sheet containing rapidly solidified Al-Fe-Cu- V-Si-Ni-Ce-Zr aluminum alloy powders is constructed successfully. The powders and nickel matrix are combined well in the sheet. It can be used to prepare the observation specimen for TEM and determine the hardness of single powder particle as solidified and after heat-treated. The advantages of this method are the realization of heat treatment of powders and the TEM observation of non-interfered microstructure of powders in the size of several microns.展开更多
Ni-ZrO2 nanocomposite coatings with monodispersed ZrO2 nanoparticles were prepared from the composite plating bath containing dispersant under DC electrodeposition condition. It is found that the morphology, orientati...Ni-ZrO2 nanocomposite coatings with monodispersed ZrO2 nanoparticles were prepared from the composite plating bath containing dispersant under DC electrodeposition condition. It is found that the morphology, orientation and hardness of the composite coating with monodispersed ZrO2 nanoparticles have lots of difference from the composite coating with agglomerated ZrO2 nanoparticles and pure nickel coating. Especially, the result of hardness shows that only a very low volume fraction (less than 1%) of monodispered ZrO2 nanoparticles in Ni-ZrO2 composite coatings will result in higher hardness of the coating. The hardness of Ni-ZrO2 nanocomposite coatings with monodispersed and agglomerated ZrO2 nanoparticles are HV 529 and HV 393, respectively. The hardness value of the former composite coatings is over 1.3 times higher than that of the later. All these composite coatings are 2 - 3 times higher than that of pure nickel plating (HV 207) prepared under the same conditions.展开更多
Sand-wear resistance of nano scale alumina particle reinforced nickel matrix composite coating （n-Al2O3/Ni） prepared by brush electroplating technique was investigated via wear tests in sand-contaminated oil lubrica...Sand-wear resistance of nano scale alumina particle reinforced nickel matrix composite coating （n-Al2O3/Ni） prepared by brush electroplating technique was investigated via wear tests in sand-contaminated oil lubricant, comparing with that of AISI1045 steel and brush electroplated Ni coating. Effects of testing load, sand content and sand size on worn volume of the three materials, and also coating surface roughness on worn volume of the brush electroplated coatings were accessed. Results show that the worn volume of all the three materials increases with increasing of testing load, sand content and sand size. In the same conditions, n-Al2O3/Ni composite coating has the smallest worn volume while AISI1045 steel has the largest because of the n-Al2O3 particle effects. As to n-Al2O3/Ni and Ni coatings, the surface-polished coatings have obviously lower worn volume than the as-plated coatings. The brush electroplated n-Al2O3/Ni composite coating was employed to remanufacture the sand-worn bearing seats of a heavy vehicle and good results were gained.展开更多
基金supported by Key-Area Research and Development Program of Guangdong Province(No.2023B0101040002)National Natural Science Foundation of China(Nos.62304143,52303092 and 62274172)Guangdong Basic and Applied Basic Research Fund(No.2022B1515120037).
文摘Copper metal is widely electroplated for microelectronic interconnections such as redistribution layers(RDL),pillar bumps,through silicon vias,etc.With advances of multilayered RDL,via-on-via structures have been developed for ultrahigh-density any-layer interconnection,which expects superconformal filling of interlayer low aspect-ratio vias jointly with coplanar lines and pads.However,it poses a great challenge to electrodeposition,because current via fill mechanisms are stemming from middle to high aspect-ratio(>0.8)vias and lacking applicability in low aspect-ratio(<0.3)RDL-vias,where via geometry related electric-flow fields coupling must be reconsidered.In the present work,a four-additive strategy has been developed for RDL-vias fill and thoroughly investigated from additive electrochemistry,in situ Raman spectroelectrochemistry,and quantum chemistry perspectives.A novel adsorbate configuration controlled(ACC)electrodeposition mechanism is established that at weak-convection bilateral edges and lower corners,the adsorbate displays a weakly-adsorbing configuration to assist accelerator-governed deposition,whereas at strong-convection center,the adsorbate exhibits a mildlyadsorbing configuration to promote leveler-determined inhibition.Deposit profiles can be tailored from dished,flat to domed,depending on predominance of leveler over accelerator.This study should lay theoretical and practical foundations in design and application of copper electroplating additives of multiple adsorbate configurations to cope with complicated interconnect scenarios.
基金the National Natural Science Foundation of China(Nos.51921003 and 51775275)the Major Special Projects of Aero-engine and Gas Turbine of China(2017-VII-0002-0095)+1 种基金the Six Talents Summit Project in Jiangsu Province of China(No.JXQC-002)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.KYCX180256)。
文摘This paper evaluates the performance of creep feed grindingγ-TiAl intermetallic(Ti-45 Al-2 Mn-2 Nb)using electroplated diamond wheels.Firstly,a comparative analysis with the grinding results by using electroplated CBN wheels was conducted,mainly involving abrasive wheel wear behavior and maximum material removal rate below surface burn limit.It was found that the diamond wheel would produce much better grinding results including lower wheel wear rate and higher maximum material removal rate.Then the surface integrity obtained at different level of material removal rate was characterized with the utilization of the diamond wheel.The poor ductility of thisγ-TiAl intermetallic material was found to have a marginal effect on the surface integrity,as no severe surface defects such as material pullout were generated during the stable wheel wear stage.For the involved operating parameters,a deformation layer was produced with~10μm or more in thickness depending on the material removal rate used.Meanwhile,a work-hardened layer extending to more than 100μm was produced with a maximum microhardness of above 520 HV0.05(bulk value 360 HV0.05).The residual stress remained compressive,with a value of above-100 MPa and even up to-500 MPa for an elevated material removal rate.Shearing chip was the main chip type,indicating good wheel sharpness in the grinding process.
基金supported by National Natural Science Foundation of China (Grant No. 50535030)National Basic Research Program of China (973 Program, Grant No. 2006CB300407)
文摘Mechanical properties of structural materials are particularly important for design, performance realization and reliability analysis of microelectromechanical systems （MEMS）. Furthermore, accurate database of mechanical properties at the micro scale can provide indispensable reference for establishing MEMS standard. Electroplated nickel film is one of the most favored structural materials used in MEMS, thus its mechanical properties has been studied for many years. However, the measured values show large scatter in Yotmg＇s modulus of nickel film. Young＇s modulus and yield stress of electroplated nickel film are measured by using a micro-tensile testing instrument. The tensile load applied on the specimen is measured by a load cell with accuracy 0.25 mN directly, without additional friction. Through measuring the axial stiffness coefficient of the tensile instnunent in situ, the tensile strain of the specimen is obtained by using two-serial spring model. The electroplated nickel films were fabricated from sulfarnate baths, and the gauge section is 500μm long and 10μm wide nominally, and thickness range between 25 μm and 50μm. The obtained Young＇s modulus from tensile testing is 83＋6 GPa for nickel specimens electroplated at current density of 20 mA/cm2 and it increases to 124＋5 GPa as current density is decreased to 10 mA/cm2. The phenomena are interpreted in terms of porosity of microstructure. The higher current density produced rnicrostucture with low density and high volume fraction of pores, and the microstructure of high porosity corresponds to a lower modulus. The measured values of Young＇s modulus are consistent with those of calculated from the exponential empirical formula between Young＇s modulus and porosity. The micro-tensile testing instrument can also be used for mechanical measurement of other MEMS films.
基金the National Science Foundation of China (No.50571003)
文摘Galvanic corrosion behavior of Ti-1023 titanium alloy coupled 30CrMnSiA steel was investigated in 3.5% NaCl solution. Particular attention was given to the effect of three different electroplated coatings on corrosion behavior of the galvanic couple. Galvanic corrosion test was conducted on Ti-1023 titanium alloy which coupled Ni-electroplated 30CrMnSiA, Zn-electroplated 30CrMnSiA, Cd-electroplated 30CrMnSiA and bare 30CrMnSiA, respectively. Corrosion properties including open circuit potential （Eoc）, galvanic corrosion potential （Eg）, and galvanic corrosion current （lg） were monitored. Corrosion morphology was observed by optical microscope （OM） and corrosion mechanism was analyzed and discussed. The results show that the three electroplated coatings improve the corrosion resistance of the anode in different magnitudes. Ni-electroplated 30CrMnSiA and Cd-electroplated 30CrMnSiA coatings are found to be least susceptible to galvanic corrosion when coupled Ti-1023 titanium alloy. Zn-electroplated 30CrMnSiA is moderately susceptible to galvanic corrosion. But the bare 30CrMnSiA is highly susceptible to galvanic corrosion in corrosive environment.
基金the National Natural Science Foundation of China(No.51875050)Hunan Provincial Natural Science Foundation of China(No.2019JJ40293)Changsha City Planned Science and Technology Project(No.kq1907088)。
文摘To improve the bonding strength between the nickel bond and the hub of the electroplated diamond grinding wheel,a hybrid technique was proposed to combine laser prequenching steel substrate and post-electroplating nickel.To validate the effectiveness of the proposed technique,AISI 1045 substrate was nickel-coated.The bonding properties between the electroplated nickel coating and substrate with or without laser-discrete-quenching were discussed comparatively by scratch,indentation,and thermal shock tests.The results show that the prequenching treatment leads to phase transformation of AISI 1045 microstructure from the mixed pearlite and ferrite phases into the martensitic phase.Since the martensitic phase is characterized as a high corrosion resistance,the interface of substrate/coating is smooth and flat in the prequenched zone,and the coating is bonded well with the steel substrate.In contrast to the steel substrate without pre-quenching treatment,the proposed technique significantly enhanced the bonding strengths of the electroplated nickel-coating.On one hand,the average hardness of electroplated nickel-coating on the laser pre-quenched zone is increased by 18.7%,and the scratch depth with the same load become narrower and shallower.On the other hand,the coefficient of friction(CoF)and the vibration amplitude are reduced,and the coating is bonded effectively with the substrate to inhibit the crack initialization at the interface.This prevents effectively the coating from peeling off and improves significantly the thermal shock resistance property.
基金supported by the National Natural Science Foundation of China(Grant No.51105346)
文摘Cracks may easily occur in the fusion weld between vanadium alloys and stainless steel due to the brittle intermetallics and welding stress. The high vacuum electron beam braze-welding has been successfully used to join vanadium alloy（V-5Cr-STi） to stainless steel （HR-2） with electroplated Cu and Ag coating. To investigate the effects of electroplated coating on the weldability, the joint appearaace, the microstrueture and the mechanical properties of the joints have been thoroughly analyzed. The results show that the joint surface configuration was good and root reinforcement was full and smooth. A reaction zone （RZ） was gained on the interface between the V-5 Cr-5 Ti alloy and HR-2 stainless steel base metals. The width of reaction zone at the top of the joint was up to O. 65 mm, wider than that in the bottom of the joint （ 0.46 mm）. The reaction zone consisted of considerably smaller dendritic structures with an average grain size of less than 10μm. Element Ag and Cu almost enriched the interface between V-SCr-5Ti alloy substrate and RZ, serving as a physical barrier which decreases or avoids the formation of intermetallics. The maximum tensile strength of vanadium alloy^stainless steel dissimilar alloy joint was more than 300 MPa. The joint was defects free.
基金Supported by National Natural Science Foundation of China(Grant Nos.52275405,52275311,51875050)Hunan Provincial Key Research and Development Program(Grant No.2021GK2021).
文摘The ability to predict a grinding force is important to control,monitor,and optimize the grinding process.Few theoretical models were developed to predict grinding forces when a structured wheel was used in a grinding process.This paper aimed to establish a single-grit cutting force model to predict the ploughing,friction and cutting forces in a grinding process.It took into the consideration of actual topography of the grinding wheel,and a theoretical grinding force model for grinding hardened AISI 52100 by the wheel with orderly-micro-grooves was proposed.The model was innovative in the sense that it represented the random thickness of undeformed chips by a probabilistic expression,and it reflected the microstructure characteristics of the structured wheel explicitly.Note that the microstructure depended on the randomness of the protruding heights and distribution density of the grits over the wheel.The proposed force prediction model was validated by surface grinding experiments,and the results showed(1)a good agreement of the predicted and measured forces and(2)a good agreement of the changes of the grinding forces along with the changes of grinding parameters in the prediction model and experiments.This research proposed a theoretical grinding force model of an electroplated grinding wheel with orderly-micro-grooves which is accurate,reliable and effective in predicting grinding forces.
基金Project (51172102/E020801) supported by the National Natural Science Foundation of ChinaProject (31805) supported by Doctoral Fund of Liaocheng University, China
文摘Ni coating was deposited on carbon steel by a mechanical attrition enhanced electroplating （MAEE） process. During the electroplating, the mechanical attrition（MA） was introduced by impact of glass balls on the sample surface with a special vibrating frequency. The surface and cross-sectional images of Ni coating were observed with SEM. The microstructure and crystallinity of coating were examined with TEM and XRD. The electrochemical performance of coating was measured with polarization curves and electrochemical impedance spectroscopy （EIS） and its mechanical behaviours, such as tensile strength and hardness, were studied. The results show that the MA has significant effects on the microstructure and property of the electroplated Ni coating. By MA, the coating becomes smooth, compact, thin and has refined grains and is free of cracks and pores. Consequently, the adhesion, tensile strength, hardness and corrosion resistance of coating are improved significantly.
基金supported by the Walailak Universitys Research Unit Fund
文摘Monolayered Co and trilayered Co/Cu/Co were electroplated on 485 μm-diameter Cu wires using the bath pH 2.5. These wires can be functioned as magnetic sensors owing to their magnetoimpedance （MI） effect. By measuring at four different frequencies （100, 250, 500, and 1000 kHz） and Co thicknesses （2.5, 5.0, 10.0, and 25.0μm）, the MI ratio of electroplated Co on Cu wires tended to increase with increasing Co thickness and frequency of the driving current. The Co/Cu/Co on Cu wires exhibited even higher MI ratio. The magnetic layer also regulated the magnetic inductions and anisotropy regardless of the size of nonmagnetic core. Nevertheless, the diameter of the Cu core had a significant effect on the MI ratio. By comparing with the 47.7 μm-diameter Ag cores electroplated by Co and Co/Cu/Co of the same thickness, the Cu cores with a larger diameter gave rise to a larger MI ratio because their lower electrical resistance enhanced the crossing effect. Substantial MI ratio was observed even in a low frequency regime because the skin effect occurred at a low frequency in the case of electroplated wires with large core diameters.
文摘Ferromagnetic resonance （FMR）, Ferromagnetic antirresonance （FMAR） and low field magnetoimpedance （MI） are the characteristic features of high frequency losses in applied fields. While some results on FMR and FMAR in CoFeNi electroplated wires were reported earlier, here we present microwave absorption in CuBe wires electroplated by 1 μm FeCoNi magnetic layer at very low fields. These data are comparatively analysed together with longitudinal hysteresis loops in order to reveal the correlation between power absorption and magnetization processes. Microwave studies are made by using the cavity perturbation method at 9.65 GHz for a DC field parallel to the sample axis, and with microwave magnetic field hrf parallel or perpendicular to the wire axis. Two peaks have been observed in all samples, one is due to FMR, and the other is, at very low fields, related to MI. The MI peaks represent minima in power absorption. By comparing with the hysteresis loop we remark the close correspondence between the MI phenomena in the axial mode and the concomitant magnetization process.
基金the financial support for this work by the National Natural Science Foundation of China (No.51235004 and No.51375235)the Fundamental Research Funds for the Central Universities (No.NE2014103)the Science and Technology Supporting Program of Jiangsu Province (No.BE2013109 and No.BY2014003-008)
文摘In order to develop the high-efficiency and precision machining technique of TiCp/Ti - 6Al-4V particulate reinforced titanium matrix composites （PTMCs）, high-speed grinding experiments were conducted using the single-layer electroplated cubic boron nitride （CBN） wheel and brazed CBN wheel, respectively. The comparative grinding performance was studied in terms of grinding force, grinding temperature, grinding-induced surface features and defects. The results display that the grinding forces and grinding temperature obtained with the brazed CBN wheel are always lower than those with the electroplated CBN wheel. Though the voids and microcracks are the dominant grinding-induced surface defects, the brazed CBN wheel produces less surface defects compared to the electroplated wheel according to the statistical analysis results. The max mum materials removal rate with the brazed CBN wheel is much higher than that with the electroplated one. All above indicate that the single-layer brazed CBN super-abrasive wheel is more suitable for high-speed grinding of PTMCs than the electroplated counterpart.
基金Sponsored by Innovation team item fund of Liaoning Province ( 2008T164)
文摘The cutting process of electroplated diamond wire saw was researched on the basis of impulse and vibration machining theories. The different contact states in the cutting process were analyzed by using the finite element method. It shows that the cutting stress is uniformly distributed along the direction of the workpiece width in the steady state. A mathematical equation of sawing trajectory was established by using the superposition principle and the cutting experiment of wire saw to calculate the cutting trajectory. The comparison of the theoretical trajectory with the calculated one indicates that the error is less than 15%. The research results provide a theoretic basis for optimization of the saw's cutting process parameters.
基金Bright Sparks Unit,University Malaya for the financial support
文摘Electroplating has been used to produce Cu-Bi coatings. The crystal structure and lattice parameters of Cu in Cu-Bi composite coating were measured and compared with Cu coating. The mechanical properties of the coatings were also studied. It was found that the deposition parameters have significant effect on the mechanical properties of the Cu-Bi coatings. The microhardness has been improved from HVso165 of Cu coating to HVs0 250 of Cu-Bi composite coating prepared at 50 mA/cm2 for 20 min. Correspondingly, wear resistance of the Cu-Bi composite coating has also been enhanced significantly.
基金Project(2012QTXM0751)supported by the Scientific and Technological Research Project,State Grid,China
文摘Cu/Al laminar composite was prepared by dipping Zn layer and then electroplating Cu thick layer on pure Al sheet.During annealing the Cu/Al composites at temperature from 473 to 673 K, the Cu/Al interfacial diffusion and reaction and itskinetics and also the electrical resistivity of the composites were studied. The results show that no Cu?Al IMC layer is observable asthe composites are annealed at 473 K for time till 360 h, indicating that the Zn intermediate layer can effectively suppress the Cu/Alinterfacial diffusion. However, as the composites are annealed at 573 K and above, Zn atoms in the Zn layer dissolve into the Culayer. Tri-layered reaction product of CuAl2/CuAl/Cu9Al4 then forms from the Al side to the Cu side. The IMC layer follows thediffusion-controlled growth kinetics. Electrical resistivity of the Cu/Al composites increases with the increase of the annealingtemperature and time.
基金The Key Laboratory Project of State Oceanic Administration for Marine Ecosystem and Biogeochemistry of China under contract No.529101-X21601the Foundation from Wendy Schmidt Ocean Health XPRIZE and the Southern California Coastal Water Research Project
文摘Resulting from the rising levels of atmospheric carbon, ocean acidification has become a global problem. It has significant impacts on the development, survival, growth and physiology of marine organisms. Therefore, a high- precision sensor is urgently needed to measure the pH of sea-water. Iridium wire with a diameter of 0.25 mm is used as the substrate, and an Ir/Ir（OH）x pH electrode is prepared by a one-step electrochemical method in a LiOH solution at the room temperature. A scanning electron microscope （SEM） observation reveals that it is coated with nanoscale particles. In laboratory tests, the electrode exhibits a very promising pH response, with an ideal Nernst slope （56.14-59.52）, fast response, good stability and long fife-span in tested pH buffer solutions. For a sea trial, four pH electrodes and one Ag/AgC1 reference electrode are integrated with a self-made chemical sensor, and a profile detection of nearly 70 m is implemented near Newport Harbor, California on August 3, 2015. The results reflect that the pH value measured by the sensor is very close to the data given by Sea-Bird 911 plus CTD, with a difference value ranging from 0.000 075 to 0.064 719. And the sensor shows a better data matching degree in 0-40 m water depth. In addition, the high precision and accuracy of the sensor make it possible to use in the ocean observation field.
基金supported by the National Natural Science Foundation of China (No.50671006)
文摘Ni-P-SiC composite coatings were electroplated on carbon steel substrate assisted by mechanical attrition （MA）. The MA action was conducted by dispersing glass balls on the cathodic surface, vibrating in the horizontal direction. The experimental results show that, under the assistant of MA action, the adhesion of Ni-P-SiC coating on the steel substrate can be improved effectively, and the Ni-P-SiC coatings exhibit a crystallized structure and Ni-P matrix can combine tightly with SiC particles, and the hardness and corrosion resistance of these coatings increase markedly. During heat treatment, the defects produced in conventional Ni-P-SiC composite coatings can be avoided assisted by MA action. Both of the wear of these coatings can be improved further.
基金financially supported by the National Key Research and Development Program of China(No.2016YFC0700905)the National Natural Science Foundation of China(Grant No.51674232,No.51972304 and No.51702331)。
文摘Graphite flake/Cu composite has attracted tremendous attention as a promising heat sinks materials owing to its easy machinability and superior thermal properties. However, its preparation process still faces several technological limitations including complex, time-consuming and costly synthetic approaches. In this work, a facile and scalable intermittently electroplated method is applied to prepare Cu-coated graphite flake composite powders, which are subsequently sintered into dense composite bulks. The results show that the graphite flake is successfully coated with a uniform and compact Cu shell,which effectively inhibits the segregation accumulation of graphite flakes and contributes to homogeneous distribution of graphite in the sintered graphite flake/Cu composites. The as-sintered composites exhibit an excellent thermal conductivity of 710 W·m-1·K-1and an outstanding bending strength of 93 MPa. Such performance, together with the simple, efficient powder-preparation process, suggests that the present strategy may open up opportunities for the development of thermal management materials.
文摘Baded on the study of nickel electroplating technology at room temperature, the plated sheet containing rapidly solidified Al-Fe-Cu- V-Si-Ni-Ce-Zr aluminum alloy powders is constructed successfully. The powders and nickel matrix are combined well in the sheet. It can be used to prepare the observation specimen for TEM and determine the hardness of single powder particle as solidified and after heat-treated. The advantages of this method are the realization of heat treatment of powders and the TEM observation of non-interfered microstructure of powders in the size of several microns.
文摘Ni-ZrO2 nanocomposite coatings with monodispersed ZrO2 nanoparticles were prepared from the composite plating bath containing dispersant under DC electrodeposition condition. It is found that the morphology, orientation and hardness of the composite coating with monodispersed ZrO2 nanoparticles have lots of difference from the composite coating with agglomerated ZrO2 nanoparticles and pure nickel coating. Especially, the result of hardness shows that only a very low volume fraction (less than 1%) of monodispered ZrO2 nanoparticles in Ni-ZrO2 composite coatings will result in higher hardness of the coating. The hardness of Ni-ZrO2 nanocomposite coatings with monodispersed and agglomerated ZrO2 nanoparticles are HV 529 and HV 393, respectively. The hardness value of the former composite coatings is over 1.3 times higher than that of the later. All these composite coatings are 2 - 3 times higher than that of pure nickel plating (HV 207) prepared under the same conditions.
文摘Sand-wear resistance of nano scale alumina particle reinforced nickel matrix composite coating （n-Al2O3/Ni） prepared by brush electroplating technique was investigated via wear tests in sand-contaminated oil lubricant, comparing with that of AISI1045 steel and brush electroplated Ni coating. Effects of testing load, sand content and sand size on worn volume of the three materials, and also coating surface roughness on worn volume of the brush electroplated coatings were accessed. Results show that the worn volume of all the three materials increases with increasing of testing load, sand content and sand size. In the same conditions, n-Al2O3/Ni composite coating has the smallest worn volume while AISI1045 steel has the largest because of the n-Al2O3 particle effects. As to n-Al2O3/Ni and Ni coatings, the surface-polished coatings have obviously lower worn volume than the as-plated coatings. The brush electroplated n-Al2O3/Ni composite coating was employed to remanufacture the sand-worn bearing seats of a heavy vehicle and good results were gained.
