Cr-SiC nanocomposite coatings with various contents of SiC nanoparticles were prepared by electrodeposition in optimized Cr plating bath containing different concentrations of SiC nanoparticles. Direct current electro...Cr-SiC nanocomposite coatings with various contents of SiC nanoparticles were prepared by electrodeposition in optimized Cr plating bath containing different concentrations of SiC nanoparticles. Direct current electrocodeposition technique was used to deposit chromium layers with and without SiC nanoparticles on mild carbon steel. The effects of current density, stirring rate and concentration of nanoparticles in the plating bath were investigated. Scanning electron microscopy was used to study surface morphology. Energy dispersive analysis technique was used to verify the presence of SiC nanoparticles in the coated layers. The corrosion behaviors of coatings were investigated by potentiodynamic polarization and electrochemical impedance spectroscopy methods in 0.05 mol/L HCl, 1 mol/L NaOH and 3.5% NaCl （mass fraction）, respectively. Microhardness measurements and pin-on- disc tribometer technique were used to investigate the wear behavior of the coatings.展开更多
Design a precision electroplating mechanical structure for automobiles based on finite element analysis method and analyze its mechanical properties.Taking the automobile steering knuckle as the research object,ABAQUS...Design a precision electroplating mechanical structure for automobiles based on finite element analysis method and analyze its mechanical properties.Taking the automobile steering knuckle as the research object,ABAQUS parametric modeling technology is used to construct its three-dimensional geometric model,and geometric simplification is carried out.Two surface treatment processes,HK-35 zinc nickel alloy electroplating and pure zinc electroplating,were designed,and the influence of different coatings on the mechanical properties of steering knuckles was compared and analyzed through numerical simulation.At the same time,standard specimens were prepared for salt spray corrosion testing and scratch method combined strength testing to verify the numerical simulation results.The results showed that under emergency braking and composite working conditions,the peak Von Mises stress of the zinc nickel alloy coating was 119.85 MPa,which was lower than that of the pure zinc coating and the alkaline electroplated zinc layer.Its equivalent strain value was 652×10^(-6),which was lower than that of the pure zinc coating and the alkaline electroplated zinc layer.Experimental data confirms that zinc nickel alloy coatings exhibit significant advantages in stress distribution uniformity,strain performance,and load-bearing capacity in high stress zones.The salt spray corrosion test further indicates that the coating has superior corrosion resistance and coating substrate interface bonding strength,which can significantly improve the mechanical stability and long-term reliability of automotive precision electroplating mechanical structures.展开更多
Electroplating sludge(ES),a byproduct of the electroplating industry,is a significant environmental concern due to its high content of soluble heavy metals(HMs).The significance of spinel formation from ES lies in its...Electroplating sludge(ES),a byproduct of the electroplating industry,is a significant environmental concern due to its high content of soluble heavy metals(HMs).The significance of spinel formation from ES lies in its potential for HMs enrichment and environmental remediation,offering a sustainable solution for hazardous waste management.The article delves into themultifaceted recycling of HMs-rich spinel fromES,encompassing its synthesis,metal enrichment,and thermodynamic stability.The pyro-metallurgical and hydrometallurgical processes for spinel synthesis were discussed,with a focus on the critical role of thermodynamic data in predicting the stability and formation of spinel structures.The crystallographic and magnetic properties of spinels,with their applications in environmental remediation and energy storage are highlighted.The article provides a comprehensive reviewon the recycling of HMs-rich spinel fromES,offering a means to recycle HMs,mitigate ecological harm,and contribute to a circular economy through the recovery and application of valuable materials.The selective leaching of metals from ES also faces challenges,which was limited by the separation,purification steps and high energy consumption.This high energy consumption is a significant operational cost and also contributes to environmental concerns related to carbon emissions.It is essential to address the challenges through continued research and development,improved technologies,and supportive regulatory frameworks.展开更多
Cyanide-free silver electroplating was conducted in thiosulfate baths containing AgNO3 and AgBr major salts, respectively. The effects of major salt content and current density on surface quality, deposition rate and ...Cyanide-free silver electroplating was conducted in thiosulfate baths containing AgNO3 and AgBr major salts, respectively. The effects of major salt content and current density on surface quality, deposition rate and microhardness of Ag coatings were investigated. The optimized electroplating parameters were established. The adhesion strength of Ag coating on Cu substrate was evaluated and the grain size of Ag coating was measured under optimized electroplating parameters. The optimized AgNO3 content is 40 g/L with current density of 0.25 A/dm2. The deposited bright, smooth, and well adhered Ag coating had nanocrystalline grains with mean size of 35 nm. The optimized AgBr content was 30 g/L with current density of 0.20 A/dm2. The resultant Ag coating had nanocrystalline grains with mean size of 55 nm. Compared with the bath containing AgBr main salt, the bath containing AgNO3 main salt had a wider current density range, and corresponding Ag coating had a higher microhardness and a smaller grain size.展开更多
It is difficult to directly electroplate Al on Mg alloys. The effects of pretreatment parameters on the corrosion resistance of films obtained on AZ31 Mg alloy surface were studied by using potentiodynamic polarizatio...It is difficult to directly electroplate Al on Mg alloys. The effects of pretreatment parameters on the corrosion resistance of films obtained on AZ31 Mg alloy surface were studied by using potentiodynamic polarization curves, to produce a compact interfacial layer as zinc-immersion deposition. After the substrate was pretreated under optimized conditions, aluminum was electrodeposited on AZ31 from TMPAC-AlCl3 room temperature ionic liquids. The depositions were characterized by scanning electron microscope equipped with energy dispersion X-ray. The results show that the traditional pretreatment of Mg alloys was successfully used for the Al-electroplating process from TMPAC-AlCl3 ionic liquids. The entire procedure includes alkaline cleaning, chemical pickling, surface activation （400 mL/L HF acid, 10 min）, zinc-immersion （20 min） and anhydrous treatment. A relatively compact zinc-immersion film was prepared on the substrate surface. A silvery-colored satin aluminum deposition was obtained on AZ31 from TMPAC-AlCl3 using direct current plating.展开更多
A coordinative disposal process for treatment of electroplating sludge and stainless steel pickle waste liquid containing Cu, Ni, Zn, Cr and Fe etc., has been developed to recover valuable metals and to eliminate poll...A coordinative disposal process for treatment of electroplating sludge and stainless steel pickle waste liquid containing Cu, Ni, Zn, Cr and Fe etc., has been developed to recover valuable metals and to eliminate pollution. The recovery of Cu, Ni, Zn and Cr is 94%, 91%, 90% and 95%, respectively. The ammonia was recycled by the simplified process of CaO caustic distillation. The precipitated product of Cu, Ni and Zn obtained from caustic distillation of ammonia was separated by extraction or high\|pressure hydrogen reduction in an autoclave. The qualified metal salt products were obtained through extraction. The rich chromium residue from coordinative disposal was subjected to recover Cr by hydrothermal oxidation in NaOH medium and Fe\-3O\-4 was synthesized by wet methods from the residue produced by extracting Cr. Cr was a stable chemical fixed in Fe\-3O\-4 and harmless. The recovery process has been used in a pilot plant with sludge production capacity of 2000 t/a.展开更多
In order to achieve the optimum conditions for electroplating nanocrystalline nickel coating from Watts-type bath, the effect of some process parameters namely, bath temperature, current density, and saccharin additio...In order to achieve the optimum conditions for electroplating nanocrystalline nickel coating from Watts-type bath, the effect of some process parameters namely, bath temperature, current density, and saccharin addition on grain size and texture coefficient （TC= I（200）/I（111）） of the deposits were investigated by X-ray diffraction （XRD）. The results showed that in a bath containing 5 g/L saccharin, by increasing the bath temperature from 45℃ to 55℃, the grain size decreased, whereas further increase of bath temperature resulted in a contrary effect. By increasing the current density from 10 to 75 mA/cm^2, both the grain size and TC decreased, while further increase in current density had no significant effect on the grain size. At a given current density, the grain size and TC decreased rapidly by increasing the saccharin content before leveling off at 3 g/L of saccharin. Finally, based on the grain refining the optimum conditions for producing nanocrystalline nickel coating from Watts-type bath have been proposed.展开更多
The removal efficiency of copper （Cu（Ⅱ）） from an actual acidic electroplating effluent by biochars generated from canola, rice, soybean and peanut straws was investigated. The biochars simultaneously removed Cu...The removal efficiency of copper （Cu（Ⅱ）） from an actual acidic electroplating effluent by biochars generated from canola, rice, soybean and peanut straws was investigated. The biochars simultaneously removed Cu（Ⅱ） from the effluent, mainly through the mechanisms of adsorption and precipitation, and neutralized its acidity. The removal efficiency of Cu（Ⅱ） by the biochars followed the order： peanut straw char 〉 soybean straw char 〉 canola straw char 〉 rice straw char 〉〉 a commercial activated carbonaceous material, which is consistent with the alkalinity of the biochars. The pH of the effluent was a key factor determining the removal efficiency of Cu（Ⅱ） by biochars. Raising the initial pH of the effluent enhanced the removal of Cu（Ⅱ） from it. The optimum pyrolysis temperature was 400℃ for producing biochar from crop straws for acidic wastewater treatment, and the optimum reaction time was 8 hr.展开更多
Metal-coated fiber Bragg grating（FBG）temperature sensors were prepared via electroless nickel（EN）plating and tin electroplating methods on the surface of normal bare FBG.The surface morphologies of the metal-coate...Metal-coated fiber Bragg grating（FBG）temperature sensors were prepared via electroless nickel（EN）plating and tin electroplating methods on the surface of normal bare FBG.The surface morphologies of the metal-coated layers were observed under a metallographic microscope.The effects of pretreatment sequence,pH value of EN plating solution and current density of electroplating on the performance of the metal-coated layers were analyzed.Meanwhile, the Bragg wavelength shift induced by temperature was monitored by an optical spectrum analyzer.Sensitivity of the metal-coated FBG（MFBG）sensor was almost two times that of normal bare FBG sensor.The measuring temperature of the MFBG sensor could be up to 280℃,which was much better than that of conventional FBG sensor.展开更多
Ni-W-P-CeO2-SiO2 nano-composite coatings were prepared on common carbon steel surface by pulse electrodeposition of nickel, tungsten, phosphorus, rare earth （nano-CeO2） and silicon carbide （nano-SiO2） particles. T...Ni-W-P-CeO2-SiO2 nano-composite coatings were prepared on common carbon steel surface by pulse electrodeposition of nickel, tungsten, phosphorus, rare earth （nano-CeO2） and silicon carbide （nano-SiO2） particles. The effects of nano-CeO2 concentrations in electrolyte on microstructures and properties of nano-composite coatings were studied. The samples were characterized with chemical compositions, elements distributions, microhardness and microstructures. The results indicated that when nano-CeO2 concentration was controlled at 10 g/L, the nano-composite coatings possessed higher microhardness and compact microstmctures with clear outline of spherical matrix metal crystallites, fine crystallite sizes and uniform distribution of elements W, P, Ce and Si within the Ni-W-P matrix metal. Increasing the nano-CeO2 particles concentrations from 4 to 10 g/L led to refinement in grain structure and improvement of microstructures, while when increased to 14 g/L, the crystallite sizes began to increase again and there were a lot of small boss with nodulation shape appearing on the nano-composite coatings surface.展开更多
Ni-W-P coatings were electrodeposited on copper substrates by pulse electroplating.Effects of electrolyte pH(1-3),temperature(40-80°C),average current density(1-7A/dm2)and pulse frequency(200-1000Hz)on deposition...Ni-W-P coatings were electrodeposited on copper substrates by pulse electroplating.Effects of electrolyte pH(1-3),temperature(40-80°C),average current density(1-7A/dm2)and pulse frequency(200-1000Hz)on deposition rate,structure and corrosion resistance performance of Ni-W-P coatings were studied by single factor method.Surface morphology,crystallographic structure and composition of Ni-W-P coatings were investigated by means of scanning electron microscopy,X-ray diffractometry and energy dispersive X-ray spectroscopy,respectively.Corrosion resistance performances of Ni-W-P coatings were studied by potentiodynamic polarization and electrochemical impedance spectroscopy in3.5%NaCl solution(mass fraction)and soil-containing solution.It was found that the pulse electroplated Ni-W-P coatings have superior corrosion resistance performance and the electroplating parameters significantly affect the structure and corrosion resistance performance of Ni-W-P coatings.The optimized parameters of pulse electroplating Ni-W-P coatings were as follows:pH2.0,temperature60°C,average current density4A/dm2,and pulse frequency600Hz.The Ni-W-P coating prepared under the optimized parameters has superior corrosion resistance(276.8kΩ)and compact surface without any noticeable defect.展开更多
The radical polymerization of maleic anhydride（MA）,styrene（ST）with the vinyl groups introduced onto the surface of the nano-sized silica via solution polymerization method was developed.The methacryloxypropyl nano...The radical polymerization of maleic anhydride（MA）,styrene（ST）with the vinyl groups introduced onto the surface of the nano-sized silica via solution polymerization method was developed.The methacryloxypropyl nano-sized silica（MPNS）was used as macromonomer and polymerized with maleic anhydride and styrene by initiating with BPO in toluene.The structure and properties of MPNS/SMA nano-composite were characterized by FT-IR spectra and TEM.Meanwhile,it was applied as tanning agent compared with the traditional styrene-maleic anhydride copolymer in leather.It was found that the applied leather had better quality characteristics with the addition of the nano-sized silica.展开更多
An improved configuration of the membrane stack was adopted in the electrodeionization （EDI） cell to prevent precipitation of bivalent metal hydroxide during the running. The operational parameters that influenced t...An improved configuration of the membrane stack was adopted in the electrodeionization （EDI） cell to prevent precipitation of bivalent metal hydroxide during the running. The operational parameters that influenced the removal of copper ions from the dilute solution were optimized. The result showed that a moderate decrease in the inlet pH value and a moderate increase in the applied voltage could achieve a better removal effect. The steady process of electroplating wastewater treatment could be achieved with a removal efficiency of more than 99.5% and an enrichment factor of 5-14. The concentration of copper in purified water was less than 0.23 mg/L. This demonstrated the applicability of recovering heavy metal ions and purified water from electroplating effluent for industrial reuse.展开更多
The preparation process and properties of the thermally prepared Ti anodes coated with IrO2+Ta2O5 was studied. The structure and morphologies of the IrO2+Ta2O5 coatings were determined by XRD and SEM. Their electroche...The preparation process and properties of the thermally prepared Ti anodes coated with IrO2+Ta2O5 was studied. The structure and morphologies of the IrO2+Ta2O5 coatings were determined by XRD and SEM. Their electrochemical properties were studied by polarization curve and cyclic voltammetry. Trivalent chromium electroplating using Ti/IrO2+Ta2O5 anodes is carried out and the results were analyzed. Results show that this anode exhibits excellent electrochemical activity and stability in sulfate electrolysis. The electrocatalytic activity is determined not only by the content of IrO2 but also the structure and morphology of the anode coatings. The electroplating results indicats that Ti/IrO2+Ta2O5 anodes have excellent capabilities and merits in improving the stability of trivalent chromium electroplating in sulfate system.展开更多
Composite layers containing~0.8%vol Al_(2)O_(3) nanoparticles were produced on AZ91 magnesium alloy by friction stir processing(FSP).The treated layers were characterized using optical and scanning electron microscope...Composite layers containing~0.8%vol Al_(2)O_(3) nanoparticles were produced on AZ91 magnesium alloy by friction stir processing(FSP).The treated layers were characterized using optical and scanning electron microscopes,as well as microhardness and wear testing units.It was noticed that,by reducing the rotational speed and increasing the travel speed,the grain size of the treated layer reduces and its hardness increases.In addition,the presence of nano Al_(2)O_(3) reduces the grain sizes of the layers further and increases their hardness.Furthermore,FSP of AZ91 with Al_(2)O_(3) particles improved the wear resistance significantly and changed the wear mechanism from oxidation and adhesive mode in the as-received AZ91 to oxidation and abrasive in the FSPed specimens.Finally,the rotational speed of 800 rpm and the travel speed of 40 mm/min were the optimum parameters for achieving a suitable composite layer with the highest hardness and wear resistance among the treated layers.展开更多
Current machinery requires metallic materials to have better surface properties. Based on an orthogonal experimental design and analysis method, the CeO2-rein- forced nickel nano-composite coatings were prepared by di...Current machinery requires metallic materials to have better surface properties. Based on an orthogonal experimental design and analysis method, the CeO2-rein- forced nickel nano-composite coatings were prepared by direct current electrodeposition in a nickel sulfate bath containing CeO2 nanoparticles. Statistical results indicate that current density is the most significant variable in the electrodeposition processing, while temperature is the least important factor. The microstructure of Ni and Ni-CeO2 nano-composite coatings was characterized by scanning electron microscopy （SEM） equipped with energy-disper- sive spectroscopy （EDS）, and X-ray diffraction （XRD）. The microhardness of the Ni coating is enhanced by the incorporation of CeO2 nanoparticles. Potentiodynamic polarization and electrochemical impedance spectroscopy （EIS） were used to characterize the corrosion behavior of Ni and Ni-CeO2 coatings. These studies show that Ni- CeOz coating has better corrosion resistance compared to Ni coating.展开更多
Two kinds of poly（vinyl alcohol） （PVA）-silica composites were prepared with different methods. One composite was prepared by directly mixing PVA with 80 nm silica nano-particles which were made from tetraethoxysil...Two kinds of poly（vinyl alcohol） （PVA）-silica composites were prepared with different methods. One composite was prepared by directly mixing PVA with 80 nm silica nano-particles which were made from tetraethoxysilane （TEOS）. The another was obtained by the mixing PVA and hydrolyzed TEOS in the presence of acid-catalyst. The properties of the two PVA/silica hybrids were characterized by means of scanning electron microscopy （SEM）, UV-Visible spectroscopy, solubility tests, limiting oxygen index （LOI） test, tensile test and dynamical mechanical analysis （DMA）, respectively. The results indicate that PVA-TEOS composites （PT for short） display more transparency than PVA-silica nano-particles hybrids （PS for short）. At the same time, The PT composites presented more excellent performance than PS in water resistance, fire resistance and mechanical properties. Moreover, the Tg of PT increased with increasing TEOS content, while that of PS decreased.展开更多
The present paper aims to investigate the influence of the current density in the electroplating process on the microstructure, crystal texture transformations, and corrosion behavior of Ni/Co pumice multilayer nanoco...The present paper aims to investigate the influence of the current density in the electroplating process on the microstructure, crystal texture transformations, and corrosion behavior of Ni/Co pumice multilayer nanocomposite coatings. The Ni/Co pumice composite coatings were prepared by deposition of Ni, followed by the simultaneous deposition of pumice nanoparticles (NPs) in a Co matrix via an electroplating process at various current densities. Afterward, the morphology, size, topography, and crystal texture of the obtained samples were investigated. Furthermore, electrochemical methods were used to investigate the corrosion behavior of the produced coatings in a solution of 3.5wt% NaCl. The results indicated that increasing the plating current density changed the mechanism of coating growth from the cell state to the column state, in- creased the coating thickness, roughness, and texture coefficient (TC) of the Co (203) plane, and reduced the amount of pumice NPs incorporated into the Ni/Co pumice composite. The electrochemical results also indicated that increasing the current density enhanced the corrosion resistance of the Ni/Co pumice composite.展开更多
Ni-P/SiC/PTFE coating was obtained on the surface of 316L stainless steel by electrodeposition of Ni-P/SiC coating and immersion of PTFE(polytetrafluoroethylene).The surface morphology and composition were analyzed by...Ni-P/SiC/PTFE coating was obtained on the surface of 316L stainless steel by electrodeposition of Ni-P/SiC coating and immersion of PTFE(polytetrafluoroethylene).The surface morphology and composition were analyzed by scanning electron microscope and energy dispersive spectrometer.The corrosion resistance of the coating in 0.5 mol/L H2SO4+2×10−6 HF solution was studied by electrochemical method.Surface contact angle was used to test the hydrophobic properties of the coating.The results indicated that the Ni-P/SiC/PTFE coating prepared on the surface of stainless steel was uniform and compact,which significantly improved the self-corrosion potential of stainless steel.The self-corrosion current density decreased from 7.62 to 0.008μA/cm2.The durability performance of coating was tested under 0.6 V voltage and the stable corrosion current density value was 0.19μA/cm2,then wetting angle was tested after durability experiment and the value is 134.5°.展开更多
The influences of plating bath solution PH and current density on coercivity of electroplating CoNdNiMnP permanent magnetic film arrays were studied. The experiment results show that both for solution PH and current d...The influences of plating bath solution PH and current density on coercivity of electroplating CoNdNiMnP permanent magnetic film arrays were studied. The experiment results show that both for solution PH and current density there were the best depositing parameters. Too high and too low plating bath solution PH or current density both result in decreasing of the film array coercivity. When solution PH is 3.5 and current density is 5mA/cm2, the prepared film array coercivity can reach the maximum.展开更多
文摘Cr-SiC nanocomposite coatings with various contents of SiC nanoparticles were prepared by electrodeposition in optimized Cr plating bath containing different concentrations of SiC nanoparticles. Direct current electrocodeposition technique was used to deposit chromium layers with and without SiC nanoparticles on mild carbon steel. The effects of current density, stirring rate and concentration of nanoparticles in the plating bath were investigated. Scanning electron microscopy was used to study surface morphology. Energy dispersive analysis technique was used to verify the presence of SiC nanoparticles in the coated layers. The corrosion behaviors of coatings were investigated by potentiodynamic polarization and electrochemical impedance spectroscopy methods in 0.05 mol/L HCl, 1 mol/L NaOH and 3.5% NaCl （mass fraction）, respectively. Microhardness measurements and pin-on- disc tribometer technique were used to investigate the wear behavior of the coatings.
文摘Design a precision electroplating mechanical structure for automobiles based on finite element analysis method and analyze its mechanical properties.Taking the automobile steering knuckle as the research object,ABAQUS parametric modeling technology is used to construct its three-dimensional geometric model,and geometric simplification is carried out.Two surface treatment processes,HK-35 zinc nickel alloy electroplating and pure zinc electroplating,were designed,and the influence of different coatings on the mechanical properties of steering knuckles was compared and analyzed through numerical simulation.At the same time,standard specimens were prepared for salt spray corrosion testing and scratch method combined strength testing to verify the numerical simulation results.The results showed that under emergency braking and composite working conditions,the peak Von Mises stress of the zinc nickel alloy coating was 119.85 MPa,which was lower than that of the pure zinc coating and the alkaline electroplated zinc layer.Its equivalent strain value was 652×10^(-6),which was lower than that of the pure zinc coating and the alkaline electroplated zinc layer.Experimental data confirms that zinc nickel alloy coatings exhibit significant advantages in stress distribution uniformity,strain performance,and load-bearing capacity in high stress zones.The salt spray corrosion test further indicates that the coating has superior corrosion resistance and coating substrate interface bonding strength,which can significantly improve the mechanical stability and long-term reliability of automotive precision electroplating mechanical structures.
基金supported by the National Natural Science Foundation of China(Nos.52370158 and 22006053)Guangzhou Science and Technology Plan Project(No.2024A04J0821)Guangdong Provincial Education Science Planning Project(Higher Education Special Project)(No.2023GXJK108).
文摘Electroplating sludge(ES),a byproduct of the electroplating industry,is a significant environmental concern due to its high content of soluble heavy metals(HMs).The significance of spinel formation from ES lies in its potential for HMs enrichment and environmental remediation,offering a sustainable solution for hazardous waste management.The article delves into themultifaceted recycling of HMs-rich spinel fromES,encompassing its synthesis,metal enrichment,and thermodynamic stability.The pyro-metallurgical and hydrometallurgical processes for spinel synthesis were discussed,with a focus on the critical role of thermodynamic data in predicting the stability and formation of spinel structures.The crystallographic and magnetic properties of spinels,with their applications in environmental remediation and energy storage are highlighted.The article provides a comprehensive reviewon the recycling of HMs-rich spinel fromES,offering a means to recycle HMs,mitigate ecological harm,and contribute to a circular economy through the recovery and application of valuable materials.The selective leaching of metals from ES also faces challenges,which was limited by the separation,purification steps and high energy consumption.This high energy consumption is a significant operational cost and also contributes to environmental concerns related to carbon emissions.It is essential to address the challenges through continued research and development,improved technologies,and supportive regulatory frameworks.
基金Project (50771042) supported by the National Natural Science Foundation of ChinaProjects (1041005100052009HASTIT023) supported by the Program for Science and Technology Innovation Talents of Henan Province,China
文摘Cyanide-free silver electroplating was conducted in thiosulfate baths containing AgNO3 and AgBr major salts, respectively. The effects of major salt content and current density on surface quality, deposition rate and microhardness of Ag coatings were investigated. The optimized electroplating parameters were established. The adhesion strength of Ag coating on Cu substrate was evaluated and the grain size of Ag coating was measured under optimized electroplating parameters. The optimized AgNO3 content is 40 g/L with current density of 0.25 A/dm2. The deposited bright, smooth, and well adhered Ag coating had nanocrystalline grains with mean size of 35 nm. The optimized AgBr content was 30 g/L with current density of 0.20 A/dm2. The resultant Ag coating had nanocrystalline grains with mean size of 55 nm. Compared with the bath containing AgBr main salt, the bath containing AgNO3 main salt had a wider current density range, and corresponding Ag coating had a higher microhardness and a smaller grain size.
文摘It is difficult to directly electroplate Al on Mg alloys. The effects of pretreatment parameters on the corrosion resistance of films obtained on AZ31 Mg alloy surface were studied by using potentiodynamic polarization curves, to produce a compact interfacial layer as zinc-immersion deposition. After the substrate was pretreated under optimized conditions, aluminum was electrodeposited on AZ31 from TMPAC-AlCl3 room temperature ionic liquids. The depositions were characterized by scanning electron microscope equipped with energy dispersion X-ray. The results show that the traditional pretreatment of Mg alloys was successfully used for the Al-electroplating process from TMPAC-AlCl3 ionic liquids. The entire procedure includes alkaline cleaning, chemical pickling, surface activation （400 mL/L HF acid, 10 min）, zinc-immersion （20 min） and anhydrous treatment. A relatively compact zinc-immersion film was prepared on the substrate surface. A silvery-colored satin aluminum deposition was obtained on AZ31 from TMPAC-AlCl3 using direct current plating.
文摘A coordinative disposal process for treatment of electroplating sludge and stainless steel pickle waste liquid containing Cu, Ni, Zn, Cr and Fe etc., has been developed to recover valuable metals and to eliminate pollution. The recovery of Cu, Ni, Zn and Cr is 94%, 91%, 90% and 95%, respectively. The ammonia was recycled by the simplified process of CaO caustic distillation. The precipitated product of Cu, Ni and Zn obtained from caustic distillation of ammonia was separated by extraction or high\|pressure hydrogen reduction in an autoclave. The qualified metal salt products were obtained through extraction. The rich chromium residue from coordinative disposal was subjected to recover Cr by hydrothermal oxidation in NaOH medium and Fe\-3O\-4 was synthesized by wet methods from the residue produced by extracting Cr. Cr was a stable chemical fixed in Fe\-3O\-4 and harmless. The recovery process has been used in a pilot plant with sludge production capacity of 2000 t/a.
基金supported by University of Tehran andRazi University
文摘In order to achieve the optimum conditions for electroplating nanocrystalline nickel coating from Watts-type bath, the effect of some process parameters namely, bath temperature, current density, and saccharin addition on grain size and texture coefficient （TC= I（200）/I（111）） of the deposits were investigated by X-ray diffraction （XRD）. The results showed that in a bath containing 5 g/L saccharin, by increasing the bath temperature from 45℃ to 55℃, the grain size decreased, whereas further increase of bath temperature resulted in a contrary effect. By increasing the current density from 10 to 75 mA/cm^2, both the grain size and TC decreased, while further increase in current density had no significant effect on the grain size. At a given current density, the grain size and TC decreased rapidly by increasing the saccharin content before leveling off at 3 g/L of saccharin. Finally, based on the grain refining the optimum conditions for producing nanocrystalline nickel coating from Watts-type bath have been proposed.
基金supported by the Knowledge Innovation Program Foundation of the Chinese Academy of Sciences(No. KZCX2-EW-405)the National Key Technology R&D Program of China (No. 2012BAJ24B06)
文摘The removal efficiency of copper （Cu（Ⅱ）） from an actual acidic electroplating effluent by biochars generated from canola, rice, soybean and peanut straws was investigated. The biochars simultaneously removed Cu（Ⅱ） from the effluent, mainly through the mechanisms of adsorption and precipitation, and neutralized its acidity. The removal efficiency of Cu（Ⅱ） by the biochars followed the order： peanut straw char 〉 soybean straw char 〉 canola straw char 〉 rice straw char 〉〉 a commercial activated carbonaceous material, which is consistent with the alkalinity of the biochars. The pH of the effluent was a key factor determining the removal efficiency of Cu（Ⅱ） by biochars. Raising the initial pH of the effluent enhanced the removal of Cu（Ⅱ） from it. The optimum pyrolysis temperature was 400℃ for producing biochar from crop straws for acidic wastewater treatment, and the optimum reaction time was 8 hr.
基金the National Natural Science Foundation of China(No.60777038).
文摘Metal-coated fiber Bragg grating（FBG）temperature sensors were prepared via electroless nickel（EN）plating and tin electroplating methods on the surface of normal bare FBG.The surface morphologies of the metal-coated layers were observed under a metallographic microscope.The effects of pretreatment sequence,pH value of EN plating solution and current density of electroplating on the performance of the metal-coated layers were analyzed.Meanwhile, the Bragg wavelength shift induced by temperature was monitored by an optical spectrum analyzer.Sensitivity of the metal-coated FBG（MFBG）sensor was almost two times that of normal bare FBG sensor.The measuring temperature of the MFBG sensor could be up to 280℃,which was much better than that of conventional FBG sensor.
基金Applied Basic Research Plans Program of Yunnan Province(2007E187M)Scientific Research Fund (2006-02)Analysis and Measurement Research Fund (2007-22) of Kunming University of Science and Technology
文摘Ni-W-P-CeO2-SiO2 nano-composite coatings were prepared on common carbon steel surface by pulse electrodeposition of nickel, tungsten, phosphorus, rare earth （nano-CeO2） and silicon carbide （nano-SiO2） particles. The effects of nano-CeO2 concentrations in electrolyte on microstructures and properties of nano-composite coatings were studied. The samples were characterized with chemical compositions, elements distributions, microhardness and microstructures. The results indicated that when nano-CeO2 concentration was controlled at 10 g/L, the nano-composite coatings possessed higher microhardness and compact microstmctures with clear outline of spherical matrix metal crystallites, fine crystallite sizes and uniform distribution of elements W, P, Ce and Si within the Ni-W-P matrix metal. Increasing the nano-CeO2 particles concentrations from 4 to 10 g/L led to refinement in grain structure and improvement of microstructures, while when increased to 14 g/L, the crystallite sizes began to increase again and there were a lot of small boss with nodulation shape appearing on the nano-composite coatings surface.
文摘Ni-W-P coatings were electrodeposited on copper substrates by pulse electroplating.Effects of electrolyte pH(1-3),temperature(40-80°C),average current density(1-7A/dm2)and pulse frequency(200-1000Hz)on deposition rate,structure and corrosion resistance performance of Ni-W-P coatings were studied by single factor method.Surface morphology,crystallographic structure and composition of Ni-W-P coatings were investigated by means of scanning electron microscopy,X-ray diffractometry and energy dispersive X-ray spectroscopy,respectively.Corrosion resistance performances of Ni-W-P coatings were studied by potentiodynamic polarization and electrochemical impedance spectroscopy in3.5%NaCl solution(mass fraction)and soil-containing solution.It was found that the pulse electroplated Ni-W-P coatings have superior corrosion resistance performance and the electroplating parameters significantly affect the structure and corrosion resistance performance of Ni-W-P coatings.The optimized parameters of pulse electroplating Ni-W-P coatings were as follows:pH2.0,temperature60°C,average current density4A/dm2,and pulse frequency600Hz.The Ni-W-P coating prepared under the optimized parameters has superior corrosion resistance(276.8kΩ)and compact surface without any noticeable defect.
文摘The radical polymerization of maleic anhydride（MA）,styrene（ST）with the vinyl groups introduced onto the surface of the nano-sized silica via solution polymerization method was developed.The methacryloxypropyl nano-sized silica（MPNS）was used as macromonomer and polymerized with maleic anhydride and styrene by initiating with BPO in toluene.The structure and properties of MPNS/SMA nano-composite were characterized by FT-IR spectra and TEM.Meanwhile,it was applied as tanning agent compared with the traditional styrene-maleic anhydride copolymer in leather.It was found that the applied leather had better quality characteristics with the addition of the nano-sized silica.
基金Project (No. Z505060) supported by the Natural Science Foundation of Zhejiang Province, China
文摘An improved configuration of the membrane stack was adopted in the electrodeionization （EDI） cell to prevent precipitation of bivalent metal hydroxide during the running. The operational parameters that influenced the removal of copper ions from the dilute solution were optimized. The result showed that a moderate decrease in the inlet pH value and a moderate increase in the applied voltage could achieve a better removal effect. The steady process of electroplating wastewater treatment could be achieved with a removal efficiency of more than 99.5% and an enrichment factor of 5-14. The concentration of copper in purified water was less than 0.23 mg/L. This demonstrated the applicability of recovering heavy metal ions and purified water from electroplating effluent for industrial reuse.
文摘The preparation process and properties of the thermally prepared Ti anodes coated with IrO2+Ta2O5 was studied. The structure and morphologies of the IrO2+Ta2O5 coatings were determined by XRD and SEM. Their electrochemical properties were studied by polarization curve and cyclic voltammetry. Trivalent chromium electroplating using Ti/IrO2+Ta2O5 anodes is carried out and the results were analyzed. Results show that this anode exhibits excellent electrochemical activity and stability in sulfate electrolysis. The electrocatalytic activity is determined not only by the content of IrO2 but also the structure and morphology of the anode coatings. The electroplating results indicats that Ti/IrO2+Ta2O5 anodes have excellent capabilities and merits in improving the stability of trivalent chromium electroplating in sulfate system.
文摘Composite layers containing~0.8%vol Al_(2)O_(3) nanoparticles were produced on AZ91 magnesium alloy by friction stir processing(FSP).The treated layers were characterized using optical and scanning electron microscopes,as well as microhardness and wear testing units.It was noticed that,by reducing the rotational speed and increasing the travel speed,the grain size of the treated layer reduces and its hardness increases.In addition,the presence of nano Al_(2)O_(3) reduces the grain sizes of the layers further and increases their hardness.Furthermore,FSP of AZ91 with Al_(2)O_(3) particles improved the wear resistance significantly and changed the wear mechanism from oxidation and adhesive mode in the as-received AZ91 to oxidation and abrasive in the FSPed specimens.Finally,the rotational speed of 800 rpm and the travel speed of 40 mm/min were the optimum parameters for achieving a suitable composite layer with the highest hardness and wear resistance among the treated layers.
基金financially supported by the National Natural Science Foundation of China (No.61674141)the Natural Science Foundation of Liaoning Province Department of Science and Technology (No.201602401)+2 种基金the Natural Science Foundation of Liaoning Province Department of Education (No.L2015259)Anshan City Science and Technology Plan Project (No.20153413)the National Training Programs of Innovation and Entrepreneurship for Undergraduates (No.201610146027)
文摘Current machinery requires metallic materials to have better surface properties. Based on an orthogonal experimental design and analysis method, the CeO2-rein- forced nickel nano-composite coatings were prepared by direct current electrodeposition in a nickel sulfate bath containing CeO2 nanoparticles. Statistical results indicate that current density is the most significant variable in the electrodeposition processing, while temperature is the least important factor. The microstructure of Ni and Ni-CeO2 nano-composite coatings was characterized by scanning electron microscopy （SEM） equipped with energy-disper- sive spectroscopy （EDS）, and X-ray diffraction （XRD）. The microhardness of the Ni coating is enhanced by the incorporation of CeO2 nanoparticles. Potentiodynamic polarization and electrochemical impedance spectroscopy （EIS） were used to characterize the corrosion behavior of Ni and Ni-CeO2 coatings. These studies show that Ni- CeOz coating has better corrosion resistance compared to Ni coating.
基金financially supported by the National Natural Science Foundation of China(No.51173112)the Special Funds for Major Basic Research Projects of China(No.2011CB606006)
文摘Two kinds of poly（vinyl alcohol） （PVA）-silica composites were prepared with different methods. One composite was prepared by directly mixing PVA with 80 nm silica nano-particles which were made from tetraethoxysilane （TEOS）. The another was obtained by the mixing PVA and hydrolyzed TEOS in the presence of acid-catalyst. The properties of the two PVA/silica hybrids were characterized by means of scanning electron microscopy （SEM）, UV-Visible spectroscopy, solubility tests, limiting oxygen index （LOI） test, tensile test and dynamical mechanical analysis （DMA）, respectively. The results indicate that PVA-TEOS composites （PT for short） display more transparency than PVA-silica nano-particles hybrids （PS for short）. At the same time, The PT composites presented more excellent performance than PS in water resistance, fire resistance and mechanical properties. Moreover, the Tg of PT increased with increasing TEOS content, while that of PS decreased.
文摘The present paper aims to investigate the influence of the current density in the electroplating process on the microstructure, crystal texture transformations, and corrosion behavior of Ni/Co pumice multilayer nanocomposite coatings. The Ni/Co pumice composite coatings were prepared by deposition of Ni, followed by the simultaneous deposition of pumice nanoparticles (NPs) in a Co matrix via an electroplating process at various current densities. Afterward, the morphology, size, topography, and crystal texture of the obtained samples were investigated. Furthermore, electrochemical methods were used to investigate the corrosion behavior of the produced coatings in a solution of 3.5wt% NaCl. The results indicated that increasing the plating current density changed the mechanism of coating growth from the cell state to the column state, in- creased the coating thickness, roughness, and texture coefficient (TC) of the Co (203) plane, and reduced the amount of pumice NPs incorporated into the Ni/Co pumice composite. The electrochemical results also indicated that increasing the current density enhanced the corrosion resistance of the Ni/Co pumice composite.
基金Project(2018YFB1502500)supported by the National Key Research and Development Program of ChinaProject supported by State Key Laboratory of Powder Metallurgy,Central South University,China+1 种基金Projects(2020JJ5100,2018JJ3101)supported by Natural Science Foundation of Hunan Province,ChinaProject(51671085)supported by the National Natural Science Foundation of China。
文摘Ni-P/SiC/PTFE coating was obtained on the surface of 316L stainless steel by electrodeposition of Ni-P/SiC coating and immersion of PTFE(polytetrafluoroethylene).The surface morphology and composition were analyzed by scanning electron microscope and energy dispersive spectrometer.The corrosion resistance of the coating in 0.5 mol/L H2SO4+2×10−6 HF solution was studied by electrochemical method.Surface contact angle was used to test the hydrophobic properties of the coating.The results indicated that the Ni-P/SiC/PTFE coating prepared on the surface of stainless steel was uniform and compact,which significantly improved the self-corrosion potential of stainless steel.The self-corrosion current density decreased from 7.62 to 0.008μA/cm2.The durability performance of coating was tested under 0.6 V voltage and the stable corrosion current density value was 0.19μA/cm2,then wetting angle was tested after durability experiment and the value is 134.5°.
文摘The influences of plating bath solution PH and current density on coercivity of electroplating CoNdNiMnP permanent magnetic film arrays were studied. The experiment results show that both for solution PH and current density there were the best depositing parameters. Too high and too low plating bath solution PH or current density both result in decreasing of the film array coercivity. When solution PH is 3.5 and current density is 5mA/cm2, the prepared film array coercivity can reach the maximum.
