Because of an unfortunate mistake by authors,the Project(5227010679)of Foundation item was wrong.The corrected Project is shown as follows:Project(52271073).
The process of preparing anodic oxide film containing active sites and electroless nickel plating on highly active rare earth magnesium alloy was developed.The formation mechanism of electroless nickel plating on acti...The process of preparing anodic oxide film containing active sites and electroless nickel plating on highly active rare earth magnesium alloy was developed.The formation mechanism of electroless nickel plating on active anodic oxide film and the structure and properties of the composite coating were studied by several surface and electrochemical techniques.The results showed that Ag nanograins with an average size of 10 nm were embedded into the anodic oxide film with pores of 0.1−2μm.Ag nanoparticles provided a catalytic site for the deposition of Ni-B alloy,and the Ni crystal nucleus was first grown in horizontal mode and then in cylindrical mode.The corrosion potential of the composite coating increased by 1.37 V and the corrosion current reduced two orders of magnitude due to the subsequent deposition of Ni-P alloy.The high corrosion resistance was attributed to the misaligning of these micro defects in the three different layers and the amorphous structure of the Ni-P alloy in the outer layer.These findings provide a new idea for electroless nickel plating on anodic oxide film.展开更多
A novel method based on mid-frequency vibration is proposed to eliminate coating defects such as bubbles during electroless nickel plating.An automated control system for the plating,enabling precise and stable measur...A novel method based on mid-frequency vibration is proposed to eliminate coating defects such as bubbles during electroless nickel plating.An automated control system for the plating,enabling precise and stable measurements and adjustments of critical parameters such as plating solution temperature,pH,and nickel ion concentration,is also established,which significantly improves process efficiency and coating quality.Experimental results indicate that the system is capable of realizing stable operation over extended periods.A nonporous nickel-phosphorus coating with a thickness greater than 200μm is successfully obtained,with high phosphorus content,robust adhesion,and superior machinability.展开更多
In the process of electroless cobalt plating,the saccharin additive can significantly change the surface morphology,texture orientation,and conductivity of the cobalt coating layer.When the amount of saccharin was 3 m...In the process of electroless cobalt plating,the saccharin additive can significantly change the surface morphology,texture orientation,and conductivity of the cobalt coating layer.When the amount of saccharin was 3 mg·L^(-1),the cobalt coating transformed from disordered large grains to a honeycomb structure,with a preferred orientation of(002)facet on hexago-nal close-packed(HCP)cobalt crystals.The resistivity of the cobalt film decreased to 14.4μΩ·cm,and further decreased to 10.7μΩ·cm after the annealing treatment.When the concentration of saccharin was increased,the grain size was gradually refined and a“stone forest”structure was observed,with the preferred orientation remaining unchanged.The addition of saccharin also slightly improves the purity of cobalt coating to a certain extent.Through the study of the crystallization behavior of cobalt electroless plating,saccharin molecules can adsorb to specific c-sites on the cobalt dense crystal plane,inhibiting the growth of abc stacking arrangement and inducing the crystal growth in ab stacking mode,thereby achieving optimal growth of HCP(002)texture.展开更多
This paper introduces a thick 690 nickel-based alloy plate produced by the former Baosteel Special Steel Co.,Ltd.used as the steam-generator divider plate in the pressurized water reactor nuclear power plant.According...This paper introduces a thick 690 nickel-based alloy plate produced by the former Baosteel Special Steel Co.,Ltd.used as the steam-generator divider plate in the pressurized water reactor nuclear power plant.According to the product characteristics and design requirements of the thick nickel-based alloy plate,multidimensional sampling and testing were conducted to investigate its microstructure and mechanical properties.The results show that all the property indexes of the thick hot-rolled nickel-based alloy plate meet the design requirements,and there is good uniformity in the microstructure and mechanical properties in different dimensions.These findings indicate that China has mastered the core manufacturing technology of thick nickel-based alloy plates for their use as divider plates in nuclear power steam generators.展开更多
A method of electroless plating is utilized to deposit Co-Fe alloy on the surface of multi-walled carbon nanotubes （MWCNTs）,and electromagnetic parameters of MWCNTs with and without electroless plating are discussed...A method of electroless plating is utilized to deposit Co-Fe alloy on the surface of multi-walled carbon nanotubes （MWCNTs）,and electromagnetic parameters of MWCNTs with and without electroless plating are discussed. The MWCNTs covered by Co-Fe is a desirable light absorbent in wide wave band by utilizing electroless plating process in experiments. Field-emission scanning electron microscope （FESEM） and field-emission transmission electron microscope （FETEM） images as well as energy dispersive spectroscopy （EDS） results are presented to show the morphology,components and electromagnetic parameters of MWCNTs. Electromagnetic properties of MWCNTs are enhanced after electroless plating observed from contrast of results be-tween MWCNTs with and without plating. In conclusion,the covering Co-Fe on the surface of MWCNTs in 2-18 GHz frequency range has better electromagnetic properties. When the material is in the 6.5 GHz electromagnetic waves,the reflection loss is up to -10 dB,and the bandwidth more than -4 dB is 5 GHz. The excellent electromagnetic properties make it probable for MWCNTs to be utilized as absorbent in electromagnetic shielding materials.展开更多
Pretreated Mg-Li alloy sheets were pre-plated in a NiCO3？2Ni（OH）2？4H2O solution to form a thin Ni-P alloy film and then plating in a NiSO4？6H2O solution was carried out to obtain a protective coating.The surface ...Pretreated Mg-Li alloy sheets were pre-plated in a NiCO3？2Ni（OH）2？4H2O solution to form a thin Ni-P alloy film and then plating in a NiSO4？6H2O solution was carried out to obtain a protective coating.The surface morphology,structure and corrosion resistance of the coating were studied.The results showed that a flat,bright and compact plating layer,which was integrated into the matrix metal,was obtained.The P content of the Ni-P coating reached 13.56%（mass fraction）.The hardness value of the Ni-P coating was about HV 549.The polarization curve showed that the corrosion potential of the Ni-P coating reached ？0.249 V（vs SCE）.A long passivation region was found on the polarization curve,and this phenomenon indicated that the coating has an excellent anti-corrosion property.展开更多
An electroless ternary Ni-Sn-P transition layer with high corrosion resistance was applied for acid electroless nickel plating on magnesium alloys. The surface morphologies and microstructure of the traditional alkali...An electroless ternary Ni-Sn-P transition layer with high corrosion resistance was applied for acid electroless nickel plating on magnesium alloys. The surface morphologies and microstructure of the traditional alkaline electroless Ni-P and novel Ni-Sn-P transition layers were compared by SEM and XRD, and the bonding strengths between the transition layers and AZ31 magnesium alloys were tested. The corrosion resistance of the samples was analyzed by porosity test, potentiodynamic polarization, electrochemical impedance spectroscopy（EIS） in acid electroless solution at p H 4.5 and immersion test in 10% HCl. The results indicate that the transition layer is essential for acid electroless plating Ni-P coatings on magnesium alloys. Under the same thin thickness（-6 μm）, the electroless Ni-Sn-P transition layer possesses superior properties to the traditional Ni-P transition layer, including high amorphization, smooth and dense surface without pores, enhanced bonding strength and corrosion resistance. Most importantly, acid electroless Ni-P coatings can be successfully deposited on magnesium alloys by using Ni-Sn-P transition layer.展开更多
After Sn/Pd activating, the SiCp/Al composite with 65% SiC (volume fraction) was coated by electroless Ni?P alloy plating. Surface morphology of the composite and its effect on the Ni?P alloy depositing process and bo...After Sn/Pd activating, the SiCp/Al composite with 65% SiC (volume fraction) was coated by electroless Ni?P alloy plating. Surface morphology of the composite and its effect on the Ni?P alloy depositing process and bonding action of Ni and P atoms in the Ni?P alloy were studied. The results show that inhomogeneous distribution of the Sn/Pd activating points results in preferential deposition of the Ni?P alloy particles on the Al alloy and rough SiC particle surfaces and in the etched caves. The Ni?P alloy film has an amorphous structure where chemical bonding between Ni and P atoms exists. After a continuous Ni?P alloy film formed, electroless Ni?P alloy plating is not affected by surface morphology and characteristics of the SiCp/Al composite any longer, but by the electroless plating process itself. The Ni?P alloy film follows linear growth kinetics with an activation energy of 68.44 kJ/mol.展开更多
Electroless nickel plating on AZ91D substrate with a new and eco-friendly pretreatment process based on tuning an electrochemical homogeneous surface was investigated. The morphology, deposition process, chemical comp...Electroless nickel plating on AZ91D substrate with a new and eco-friendly pretreatment process based on tuning an electrochemical homogeneous surface was investigated. The morphology, deposition process, chemical composition and microstructure of Ni-P coating were studied. It is indicated that β phases are selectively removed, producing a microstructural homogeneous surface and the subsequent uniform and compact Zn immersion layer. A defect-free and well adhesive Ni-P coating can be successfully obtained due to its uniform nucleation and growth based on such pretreatment. Potentiodynamic polarization and electrochemical impedance spectroscopy （EIS） tests reveal that Ni-P coating could significantly improve the corrosion resistance of AZ91D substrate.展开更多
Electrical and electromagnetic shielding wood metal composite was prepared by using electroless nickel plating. The effects of solution amount, plating time and plating temperature on surface resistivity and electroma...Electrical and electromagnetic shielding wood metal composite was prepared by using electroless nickel plating. The effects of solution amount, plating time and plating temperature on surface resistivity and electromagnetic shielding effectiveness were investigated. And P content, microstructure and surface feature of layers obtained at different temperatures were analyzed by energy dispersion spectrometer （EDS）, X-ray diffraction （XRI）） and scanning electron microscopy （SEM）. The results showed that layers with higher electro-conductivity and electromagnetic shielding effectiveness were obtained under the optimum conditions that plating solution was 500 mL, plating time was 30 min and plating temperature was 62℃. The results showed by EDS analysis; that P content increased gradually in a small extent with plating temperature increased. It was showed by XRD and SEM analysis that layers plated at different temperatures were all microcrystalline structure and uniform and successive, which had noticeable metal luster. Those indicated that plating temperature had little influence on microstructure and surface feature under pH value invariable.展开更多
In this article, a new type of Cu-Ti3SiC2 composite powder prepared using the electroless plating technique was introduced. The initial Ti3SiC2 particles are 11 μm in diameter on an average. The Cu plating was carrie...In this article, a new type of Cu-Ti3SiC2 composite powder prepared using the electroless plating technique was introduced. The initial Ti3SiC2 particles are 11 μm in diameter on an average. The Cu plating was carried out at middle temperature （62-65℃） with the application of ultrasonic agitation. The copper deposition rate was determined by measuring the weight gain of the powder after plating. It has been found that the pretreatment of Ti3SiC2 powder is very important to obtain copper nanoparticles on the surface of Ti3SiC2 The optimum procedure before plating aimed to add activated sites and the adjustment of the traditional composition of the electroless copper plating bath could decelerate the copper deposition rate to 0.8 gm/h. X-ray diffraction （XRD） indicates that the chemical composition of the plating layer is copper. SEM images show that the surface of the Ti3SiC2 particles is successfully coated with continuous copper layer. The wetting property between the copper matrix and Ti3SiC2 can be improved so as to increase the interfacial strength.展开更多
Ni-W-P coatings were deposited on the surface of glass fibers by the electroless plating process. The bath was very stable through the palladium salt test. There was no phenomenon of peeling and blistering on the surf...Ni-W-P coatings were deposited on the surface of glass fibers by the electroless plating process. The bath was very stable through the palladium salt test. There was no phenomenon of peeling and blistering on the surface of the Ni-W-P alloy glass fibers in the thermal shock test. It showed that the deposit had high impact strength and good adhesion. The morphology of the coatings was observed by scanning electron microscope （SEM）. The elements and their contents were tested and analyzed by energy dispersion spectrometer （EDS）. The tungsten content reached up to 12.1 wt.%. The effects of the concentrations of NiSO4, Na2WO4, and NaH2PO2.H20 on the conductivity of the coatings were studied. The resistivity of the Ni-W-P alloy glass fibers reached 7.39 × 10^-3 Ωcm. The alloy coatings on glass fibers were analyzed by XRD. The results indicated that the deposit had an amorphous structure and good heat stability. The suitable work temperature range was lower than 190℃. Finally, the electromagnetic parameters of the Ni-W-P alloy glass fibers were tested and analyzed primarily. The magnetic loss reached 0.04023 and the dielectric loss reached -5.80239. The plated alloy is a kind of soft magnetic material.展开更多
Base on the analysis for the corrosion mechanism of the Mg alloys,the technology of Ni-P directly electroless plating on the Mg-10Li-1Zn alloys was studied.The effects of the pre-treatment on the morphologies of subst...Base on the analysis for the corrosion mechanism of the Mg alloys,the technology of Ni-P directly electroless plating on the Mg-10Li-1Zn alloys was studied.The effects of the pre-treatment on the morphologies of substrate and plating films were investigated,The result shows that Ni-P electroless plating could be divided two steps:the induction period and the rapid deposition period.The Ni-P film is amorphous structure:A excellent Ni-P coating can be obtained under the optimal parameter.The Ni-P coating can obviously improve the corrosion resistance of Mg alloy in variety environment.展开更多
Wood is a kind of porous natural material with very poor electro-conductivity, and it has almost no function of electromagnetic shielding. The method of electroless nickel plating was used to produce wooden material w...Wood is a kind of porous natural material with very poor electro-conductivity, and it has almost no function of electromagnetic shielding. The method of electroless nickel plating was used to produce wooden material with electrical and effective electromagnetic shielding properties. Ni-P alloy layer was obtained on wood surface. The surface feature of plated wood veneer was observed by SEM and the surface composition and microstructure of the layer under different conditions were investigated by EDS and XRD respectively. Meanwhile, the relevant surface resistivity and electromagnetic shielding effectiveness were measured. Correlations of the phosphorous content in the layer to the structure of Ni-P alloy, electro-conductivity and electromagnetic shielding of plated veneers were discussed. SEM photos showed that the surface of electroless nickel plated veneers were covered with Ni-P alloy layer entirely, which made wood veneers more like metal. At the same time, the results showed that with the decreasing of the phosphorous content in the layer, the microstructure of Ni-P alloy layer transformed to be microcrystalline and electro-conductivity and electromagnetic shielding effectiveness were improved. When the phosphorous content was less than 2.37wt pct in the layer, the microstructure of Ni-P alloy layer was microcrystalline structure and its sur- face resistivity and electromagnetic shielding effectiveness were nearly 0.5Ω/□ and 55-60dB respectively.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
Photocatalytic water splitting is a promising method for hydrogen production.Numerous efficient photocatalysts have been synthesized and utilized.However,photocatalysts without a noble metal as the co-catalyst have be...Photocatalytic water splitting is a promising method for hydrogen production.Numerous efficient photocatalysts have been synthesized and utilized.However,photocatalysts without a noble metal as the co-catalyst have been rarely reported.Herein,a CoP co-catalyst-modified graphitic-C3N4(g-C3N4/CoP)is investigated for photocatalytic water splitting to produce H2.The g-C3N4/CoP composite is synthesized in two steps.The first step is related to thermal decomposition,and the second step involves an electroless plating technique.The photocatalytic activity for hydrogen evolution reactions of g-C3N4 is distinctly increased by loading the appropriate amount of CoP quantum dots(QDs).Among the as-synthesized samples,the optimized one(g-C3N4/CoP-4%)shows exceptional photocatalytic activity as compared with pristine g-C3N4,generating H2 at a rate of 936μmol g^-1 h^-1,even higher than that of g-C3N4 with 4 wt%Pt(665μmol g^-1 h^-1).The UV-visible and optical absorption behavior confirms that g-C3N4 has an absorption edge at 451 nm,but after being composited with CoP,g-C3N4/CoP-4%has an absorption edge at 497 nm.Furthermore,photoluminescence and photocurrent measurements confirm that loading CoP QDs to pristine g-C3N4 not only enhances the charge separation,but also improves the transfer of photogenerated e--h+pairs,thus improving the photocatalytic performance of the catalyst to generate H2.This work demonstrates a feasible strategy for the synthesis of highly efficient metal phosphide-loaded g-C3N4 for hydrogen generation.展开更多
The electroless Ni-P-carbon nanotubes composite plating was studied on the copper substrate. Metallurgical microscope, scanning electronic microscope, X-ray diffractometer and micro hardness tester were used to study ...The electroless Ni-P-carbon nanotubes composite plating was studied on the copper substrate. Metallurgical microscope, scanning electronic microscope, X-ray diffractometer and micro hardness tester were used to study the structure, constitution and performance of the electroless Ni-P-carbon nanotubes composite deposit. Experiential results show that, with the increment of carbon nanotubes content in electroless plating solution, the grain size on the sample surface decreases whereas the density of grains and the hardness for composite deposit increases. Moreover, adding carbon nanotubes not only improves the degree of crystallization for the composite deposit but also helps their transformation from the amorphous state to the nanocrystal state.展开更多
The effect of nanodiamond content in electrolyte and rotational speed of the stirrer on the deposition rate of coatings, the nanodiamond content in coatings, the micro- structure and the micro-hardness of coatings wer...The effect of nanodiamond content in electrolyte and rotational speed of the stirrer on the deposition rate of coatings, the nanodiamond content in coatings, the micro- structure and the micro-hardness of coatings were studicd. A self-made pin-on-disk tribo-meter was employed to evaluate the wear resistance of prepared coatings. Re- sults show that the thickness of composite coating decreases with the rotational speed, while the micro hardness of coating and the content of nanodiamond in coating increase with increasing its content in electrolyte. The wear resistance of the composite coating deposited in an electrolye with 6 g/L nanodiamond increases by 50% in contrast with the pure Ni-P coating.展开更多
The rare earths of ytterbium, lanthanum, praseodymium, neodymium and their binary mixtures were respectively added into the traditional electroless plating solution to prepare thin palladium film on the inner surface ...The rare earths of ytterbium, lanthanum, praseodymium, neodymium and their binary mixtures were respectively added into the traditional electroless plating solution to prepare thin palladium film on the inner surface of porous ceramic tube. The experimental results shows that the addition of rare earths increases palladium deposition rates and the binary mixtures are superior to the single rare earths and the mixture of ytterbium-lanthanum is the most efficient. Adding the mixture of ytterbium-lanthanum can also reduce the plating temperature by 10 ~ 20℃, shrink the metal crystal size and improve the film densification compared to those by traditional electroless plating. A thin palladium film with 5μm was prepared and the film made a highly pure hydrogen with a molar fraction of more than 99.97% from a H2-N2 gas mixture. More attentions were paid to analyze the physical and chemical behaviors of the rare earths in palladium film preparation.展开更多
文摘Because of an unfortunate mistake by authors,the Project(5227010679)of Foundation item was wrong.The corrected Project is shown as follows:Project(52271073).
基金Project(5227010679)supported by the National Natural Science Foundation of China。
文摘The process of preparing anodic oxide film containing active sites and electroless nickel plating on highly active rare earth magnesium alloy was developed.The formation mechanism of electroless nickel plating on active anodic oxide film and the structure and properties of the composite coating were studied by several surface and electrochemical techniques.The results showed that Ag nanograins with an average size of 10 nm were embedded into the anodic oxide film with pores of 0.1−2μm.Ag nanoparticles provided a catalytic site for the deposition of Ni-B alloy,and the Ni crystal nucleus was first grown in horizontal mode and then in cylindrical mode.The corrosion potential of the composite coating increased by 1.37 V and the corrosion current reduced two orders of magnitude due to the subsequent deposition of Ni-P alloy.The high corrosion resistance was attributed to the misaligning of these micro defects in the three different layers and the amorphous structure of the Ni-P alloy in the outer layer.These findings provide a new idea for electroless nickel plating on anodic oxide film.
基金supported by the National Key Research and Development Program of China(Grant No.2023YFB3407200)the National Natural Science Foundation of China(Grant Nos.52375462 and 52035009).
文摘A novel method based on mid-frequency vibration is proposed to eliminate coating defects such as bubbles during electroless nickel plating.An automated control system for the plating,enabling precise and stable measurements and adjustments of critical parameters such as plating solution temperature,pH,and nickel ion concentration,is also established,which significantly improves process efficiency and coating quality.Experimental results indicate that the system is capable of realizing stable operation over extended periods.A nonporous nickel-phosphorus coating with a thickness greater than 200μm is successfully obtained,with high phosphorus content,robust adhesion,and superior machinability.
基金supported by National Natural Science Foundation of China(22402115,22472094)Shaanxi Special Fund for Talent Introduction(100090/1204071055).
文摘In the process of electroless cobalt plating,the saccharin additive can significantly change the surface morphology,texture orientation,and conductivity of the cobalt coating layer.When the amount of saccharin was 3 mg·L^(-1),the cobalt coating transformed from disordered large grains to a honeycomb structure,with a preferred orientation of(002)facet on hexago-nal close-packed(HCP)cobalt crystals.The resistivity of the cobalt film decreased to 14.4μΩ·cm,and further decreased to 10.7μΩ·cm after the annealing treatment.When the concentration of saccharin was increased,the grain size was gradually refined and a“stone forest”structure was observed,with the preferred orientation remaining unchanged.The addition of saccharin also slightly improves the purity of cobalt coating to a certain extent.Through the study of the crystallization behavior of cobalt electroless plating,saccharin molecules can adsorb to specific c-sites on the cobalt dense crystal plane,inhibiting the growth of abc stacking arrangement and inducing the crystal growth in ab stacking mode,thereby achieving optimal growth of HCP(002)texture.
基金sponsored by Special Fund for Indus-trial Transformation and Upgrading in Shanghai(No.GYQJ-2018-2-03)Program of Shanghai Academ-ic/Technology Research Leader(No.17XD1420200).
文摘This paper introduces a thick 690 nickel-based alloy plate produced by the former Baosteel Special Steel Co.,Ltd.used as the steam-generator divider plate in the pressurized water reactor nuclear power plant.According to the product characteristics and design requirements of the thick nickel-based alloy plate,multidimensional sampling and testing were conducted to investigate its microstructure and mechanical properties.The results show that all the property indexes of the thick hot-rolled nickel-based alloy plate meet the design requirements,and there is good uniformity in the microstructure and mechanical properties in different dimensions.These findings indicate that China has mastered the core manufacturing technology of thick nickel-based alloy plates for their use as divider plates in nuclear power steam generators.
文摘A method of electroless plating is utilized to deposit Co-Fe alloy on the surface of multi-walled carbon nanotubes （MWCNTs）,and electromagnetic parameters of MWCNTs with and without electroless plating are discussed. The MWCNTs covered by Co-Fe is a desirable light absorbent in wide wave band by utilizing electroless plating process in experiments. Field-emission scanning electron microscope （FESEM） and field-emission transmission electron microscope （FETEM） images as well as energy dispersive spectroscopy （EDS） results are presented to show the morphology,components and electromagnetic parameters of MWCNTs. Electromagnetic properties of MWCNTs are enhanced after electroless plating observed from contrast of results be-tween MWCNTs with and without plating. In conclusion,the covering Co-Fe on the surface of MWCNTs in 2-18 GHz frequency range has better electromagnetic properties. When the material is in the 6.5 GHz electromagnetic waves,the reflection loss is up to -10 dB,and the bandwidth more than -4 dB is 5 GHz. The excellent electromagnetic properties make it probable for MWCNTs to be utilized as absorbent in electromagnetic shielding materials.
基金Projects(50974114,51174060) supported by National Natural Science Foundation of ChinaProject(2008AA03Z512) supported by High-tech Research and Development Program of ChinaProject(20070145049) supported by PhD Programs Foundation of Ministry of Education of China
文摘Pretreated Mg-Li alloy sheets were pre-plated in a NiCO3？2Ni（OH）2？4H2O solution to form a thin Ni-P alloy film and then plating in a NiSO4？6H2O solution was carried out to obtain a protective coating.The surface morphology,structure and corrosion resistance of the coating were studied.The results showed that a flat,bright and compact plating layer,which was integrated into the matrix metal,was obtained.The P content of the Ni-P coating reached 13.56%（mass fraction）.The hardness value of the Ni-P coating was about HV 549.The polarization curve showed that the corrosion potential of the Ni-P coating reached ？0.249 V（vs SCE）.A long passivation region was found on the polarization curve,and this phenomenon indicated that the coating has an excellent anti-corrosion property.
基金Project(20120407)supported by the Science and Technology Key Development Plan of Jilin Province,China
文摘An electroless ternary Ni-Sn-P transition layer with high corrosion resistance was applied for acid electroless nickel plating on magnesium alloys. The surface morphologies and microstructure of the traditional alkaline electroless Ni-P and novel Ni-Sn-P transition layers were compared by SEM and XRD, and the bonding strengths between the transition layers and AZ31 magnesium alloys were tested. The corrosion resistance of the samples was analyzed by porosity test, potentiodynamic polarization, electrochemical impedance spectroscopy（EIS） in acid electroless solution at p H 4.5 and immersion test in 10% HCl. The results indicate that the transition layer is essential for acid electroless plating Ni-P coatings on magnesium alloys. Under the same thin thickness（-6 μm）, the electroless Ni-Sn-P transition layer possesses superior properties to the traditional Ni-P transition layer, including high amorphization, smooth and dense surface without pores, enhanced bonding strength and corrosion resistance. Most importantly, acid electroless Ni-P coatings can be successfully deposited on magnesium alloys by using Ni-Sn-P transition layer.
基金Project(2014DFA50860)supported by International Science&Technology Cooperation Program of China
文摘After Sn/Pd activating, the SiCp/Al composite with 65% SiC (volume fraction) was coated by electroless Ni?P alloy plating. Surface morphology of the composite and its effect on the Ni?P alloy depositing process and bonding action of Ni and P atoms in the Ni?P alloy were studied. The results show that inhomogeneous distribution of the Sn/Pd activating points results in preferential deposition of the Ni?P alloy particles on the Al alloy and rough SiC particle surfaces and in the etched caves. The Ni?P alloy film has an amorphous structure where chemical bonding between Ni and P atoms exists. After a continuous Ni?P alloy film formed, electroless Ni?P alloy plating is not affected by surface morphology and characteristics of the SiCp/Al composite any longer, but by the electroless plating process itself. The Ni?P alloy film follows linear growth kinetics with an activation energy of 68.44 kJ/mol.
基金Project(51371116)supported by the National Natural Science Foundation of ChinaProject(2009AA033501)supported by the Ministry of Science and Technology,China
文摘Electroless nickel plating on AZ91D substrate with a new and eco-friendly pretreatment process based on tuning an electrochemical homogeneous surface was investigated. The morphology, deposition process, chemical composition and microstructure of Ni-P coating were studied. It is indicated that β phases are selectively removed, producing a microstructural homogeneous surface and the subsequent uniform and compact Zn immersion layer. A defect-free and well adhesive Ni-P coating can be successfully obtained due to its uniform nucleation and growth based on such pretreatment. Potentiodynamic polarization and electrochemical impedance spectroscopy （EIS） tests reveal that Ni-P coating could significantly improve the corrosion resistance of AZ91D substrate.
基金The research was supported by the National Natural Science Foundation of China （30571454）. Natural Science Foundation of Heilongjiang Province （C0210） and Harbin City Youth Science Faud （2004AFQXJ027）.
文摘Electrical and electromagnetic shielding wood metal composite was prepared by using electroless nickel plating. The effects of solution amount, plating time and plating temperature on surface resistivity and electromagnetic shielding effectiveness were investigated. And P content, microstructure and surface feature of layers obtained at different temperatures were analyzed by energy dispersion spectrometer （EDS）, X-ray diffraction （XRI）） and scanning electron microscopy （SEM）. The results showed that layers with higher electro-conductivity and electromagnetic shielding effectiveness were obtained under the optimum conditions that plating solution was 500 mL, plating time was 30 min and plating temperature was 62℃. The results showed by EDS analysis; that P content increased gradually in a small extent with plating temperature increased. It was showed by XRD and SEM analysis that layers plated at different temperatures were all microcrystalline structure and uniform and successive, which had noticeable metal luster. Those indicated that plating temperature had little influence on microstructure and surface feature under pH value invariable.
文摘In this article, a new type of Cu-Ti3SiC2 composite powder prepared using the electroless plating technique was introduced. The initial Ti3SiC2 particles are 11 μm in diameter on an average. The Cu plating was carried out at middle temperature （62-65℃） with the application of ultrasonic agitation. The copper deposition rate was determined by measuring the weight gain of the powder after plating. It has been found that the pretreatment of Ti3SiC2 powder is very important to obtain copper nanoparticles on the surface of Ti3SiC2 The optimum procedure before plating aimed to add activated sites and the adjustment of the traditional composition of the electroless copper plating bath could decelerate the copper deposition rate to 0.8 gm/h. X-ray diffraction （XRD） indicates that the chemical composition of the plating layer is copper. SEM images show that the surface of the Ti3SiC2 particles is successfully coated with continuous copper layer. The wetting property between the copper matrix and Ti3SiC2 can be improved so as to increase the interfacial strength.
基金The project was financially supported by The Space Foundation of Supporting-Technology of China (No. 2002EK1803)the Graduate Starting Seed Fund of Northwestern Polytechnical University (No. W016663)
文摘Ni-W-P coatings were deposited on the surface of glass fibers by the electroless plating process. The bath was very stable through the palladium salt test. There was no phenomenon of peeling and blistering on the surface of the Ni-W-P alloy glass fibers in the thermal shock test. It showed that the deposit had high impact strength and good adhesion. The morphology of the coatings was observed by scanning electron microscope （SEM）. The elements and their contents were tested and analyzed by energy dispersion spectrometer （EDS）. The tungsten content reached up to 12.1 wt.%. The effects of the concentrations of NiSO4, Na2WO4, and NaH2PO2.H20 on the conductivity of the coatings were studied. The resistivity of the Ni-W-P alloy glass fibers reached 7.39 × 10^-3 Ωcm. The alloy coatings on glass fibers were analyzed by XRD. The results indicated that the deposit had an amorphous structure and good heat stability. The suitable work temperature range was lower than 190℃. Finally, the electromagnetic parameters of the Ni-W-P alloy glass fibers were tested and analyzed primarily. The magnetic loss reached 0.04023 and the dielectric loss reached -5.80239. The plated alloy is a kind of soft magnetic material.
基金National Hi-Tech Research and Development Program"863"
文摘Base on the analysis for the corrosion mechanism of the Mg alloys,the technology of Ni-P directly electroless plating on the Mg-10Li-1Zn alloys was studied.The effects of the pre-treatment on the morphologies of substrate and plating films were investigated,The result shows that Ni-P electroless plating could be divided two steps:the induction period and the rapid deposition period.The Ni-P film is amorphous structure:A excellent Ni-P coating can be obtained under the optimal parameter.The Ni-P coating can obviously improve the corrosion resistance of Mg alloy in variety environment.
基金The research was supported by the National Hi-Tech R ＆ D Program （863） of China （2002AA24515）. Natural Science Foundation of Heilonjiang Province （C0210） and Harbin City Youth Science Fund （2004AFQXJ027）.
文摘Wood is a kind of porous natural material with very poor electro-conductivity, and it has almost no function of electromagnetic shielding. The method of electroless nickel plating was used to produce wooden material with electrical and effective electromagnetic shielding properties. Ni-P alloy layer was obtained on wood surface. The surface feature of plated wood veneer was observed by SEM and the surface composition and microstructure of the layer under different conditions were investigated by EDS and XRD respectively. Meanwhile, the relevant surface resistivity and electromagnetic shielding effectiveness were measured. Correlations of the phosphorous content in the layer to the structure of Ni-P alloy, electro-conductivity and electromagnetic shielding of plated veneers were discussed. SEM photos showed that the surface of electroless nickel plated veneers were covered with Ni-P alloy layer entirely, which made wood veneers more like metal. At the same time, the results showed that with the decreasing of the phosphorous content in the layer, the microstructure of Ni-P alloy layer transformed to be microcrystalline and electro-conductivity and electromagnetic shielding effectiveness were improved. When the phosphorous content was less than 2.37wt pct in the layer, the microstructure of Ni-P alloy layer was microcrystalline structure and its sur- face resistivity and electromagnetic shielding effectiveness were nearly 0.5Ω/□ and 55-60dB respectively.
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supported by the National Natural Science Foundation of China(51602207)the Doctoral Scientific Research Foundation of Liaoning Province(20170520011)+3 种基金the Program for Liaoning Excellent Talents in Universities(LR2017074)the Open Project Program of the State Key Laboratory of Photocatalysis on Energy and Environment(SKLPEE-201810)Fuzhou University,the Scientific Research Project of the Educational Department of Liaoning Province(LQN201712)Shenyang Excellent Talents in Universities(RC180211)~~
文摘Photocatalytic water splitting is a promising method for hydrogen production.Numerous efficient photocatalysts have been synthesized and utilized.However,photocatalysts without a noble metal as the co-catalyst have been rarely reported.Herein,a CoP co-catalyst-modified graphitic-C3N4(g-C3N4/CoP)is investigated for photocatalytic water splitting to produce H2.The g-C3N4/CoP composite is synthesized in two steps.The first step is related to thermal decomposition,and the second step involves an electroless plating technique.The photocatalytic activity for hydrogen evolution reactions of g-C3N4 is distinctly increased by loading the appropriate amount of CoP quantum dots(QDs).Among the as-synthesized samples,the optimized one(g-C3N4/CoP-4%)shows exceptional photocatalytic activity as compared with pristine g-C3N4,generating H2 at a rate of 936μmol g^-1 h^-1,even higher than that of g-C3N4 with 4 wt%Pt(665μmol g^-1 h^-1).The UV-visible and optical absorption behavior confirms that g-C3N4 has an absorption edge at 451 nm,but after being composited with CoP,g-C3N4/CoP-4%has an absorption edge at 497 nm.Furthermore,photoluminescence and photocurrent measurements confirm that loading CoP QDs to pristine g-C3N4 not only enhances the charge separation,but also improves the transfer of photogenerated e--h+pairs,thus improving the photocatalytic performance of the catalyst to generate H2.This work demonstrates a feasible strategy for the synthesis of highly efficient metal phosphide-loaded g-C3N4 for hydrogen generation.
文摘The electroless Ni-P-carbon nanotubes composite plating was studied on the copper substrate. Metallurgical microscope, scanning electronic microscope, X-ray diffractometer and micro hardness tester were used to study the structure, constitution and performance of the electroless Ni-P-carbon nanotubes composite deposit. Experiential results show that, with the increment of carbon nanotubes content in electroless plating solution, the grain size on the sample surface decreases whereas the density of grains and the hardness for composite deposit increases. Moreover, adding carbon nanotubes not only improves the degree of crystallization for the composite deposit but also helps their transformation from the amorphous state to the nanocrystal state.
基金supported by the Jiangsu Key Laboratory for Materials Tribology (No.kjsmcx0901)
文摘The effect of nanodiamond content in electrolyte and rotational speed of the stirrer on the deposition rate of coatings, the nanodiamond content in coatings, the micro- structure and the micro-hardness of coatings were studicd. A self-made pin-on-disk tribo-meter was employed to evaluate the wear resistance of prepared coatings. Re- sults show that the thickness of composite coating decreases with the rotational speed, while the micro hardness of coating and the content of nanodiamond in coating increase with increasing its content in electrolyte. The wear resistance of the composite coating deposited in an electrolye with 6 g/L nanodiamond increases by 50% in contrast with the pure Ni-P coating.
基金Project supported by Science and Technology Committee of Jiangxi Province
文摘The rare earths of ytterbium, lanthanum, praseodymium, neodymium and their binary mixtures were respectively added into the traditional electroless plating solution to prepare thin palladium film on the inner surface of porous ceramic tube. The experimental results shows that the addition of rare earths increases palladium deposition rates and the binary mixtures are superior to the single rare earths and the mixture of ytterbium-lanthanum is the most efficient. Adding the mixture of ytterbium-lanthanum can also reduce the plating temperature by 10 ~ 20℃, shrink the metal crystal size and improve the film densification compared to those by traditional electroless plating. A thin palladium film with 5μm was prepared and the film made a highly pure hydrogen with a molar fraction of more than 99.97% from a H2-N2 gas mixture. More attentions were paid to analyze the physical and chemical behaviors of the rare earths in palladium film preparation.
