Direct electroless Ni-P plating was done on AZ91D magnesium alloy by immersing magnesium AZ91D samples into a bath containing Nickel sulphate.The nucleation mechanism of Ni-P deposits on the AZ91D magnesium alloy in t...Direct electroless Ni-P plating was done on AZ91D magnesium alloy by immersing magnesium AZ91D samples into a bath containing Nickel sulphate.The nucleation mechanism of Ni-P deposits on the AZ91D magnesium alloy in the presence of surfactants and nano-additives was studied by using SEM.The electroless Ni-P deposits were preferentially nucleated on the β Mg_(17)Al_(12) phase of AZ91D magnesium alloy.Ni-P coating was coated uniformly in the presence of surfactants.Effect of surfactant C-Tab with varying quantities was studied.Addition of surfactant C-Tab homogenized the Ni-P deposition on AZ91D magnesium alloy surface.The effect produced by surfactant C-Tab was maximum with minimum addition(1 g/l)of surfactant C-Tab further increase in the surfactant C-Tab quantity did not brought much changes in morphology.Effect of surfactant SLS was studied using SEM.Surfactant SLS when incorporated in small amounts(6 g/l and 12 g/l)only exerted a slight influence in Ni-P deposition on AZ91D alloy surface.However Ni-P deposition was more uniform and spread throughout the surface with the addition of SLS surfactant(18 g/l).Effect of nano additives Al_(2)O_(3),ZnO,SiO_(2) were studied.Nano additive Al_(2)O_(3) enhanced the deposition of Ni-P on AZ91D alloy when added in 0.6 g/l quantity.SiO_(2) addition also gave the same results.ZnO addition influenced the Ni-P deposition on AZ91D alloy positively.Ni-P surface coating was coated more uniform and spread throughout the surface with the addition of surfactants and nano-additives.展开更多
The paper presents the results of a systematic study of the influence of nano-additives of various concentrations,average sizes and composition on the temperature dependence of the viscosity and rheological behavior o...The paper presents the results of a systematic study of the influence of nano-additives of various concentrations,average sizes and composition on the temperature dependence of the viscosity and rheological behavior of water-based drilling fluids.Typical compositions of drilling fluids,such as water suspensions of various clay solutions and gammaxan-based polymer solutions,were considered.Hydrophilic nanoparticles of silicon and aluminum oxides were used as nano-additives at concentrations ranging from 0.25 to 3 wt%.The average nanoparticle size varied from 10 to 151 nm.The temperature of drilling fluids varied from 25℃ to 80℃.It is shown that the addition of nanoparticles to drilling fluids leads to a significant change in their rheological properties depending on the temperature.It was found that with increasing temperature,the yield stress and consistency index of drilling fluids with nanoparticles increase,while the behavior index,on the contrary,decreases.This behavior depends on the size of the nanoparticles.As the particle size increases,their influence on the temperature dependence of the drilling fluids’viscosity increases.In general,it is shown that the addition of nanoparticles makes the viscosity of drilling fluid more stable with regard to the temperature.This is an essential fact for practical application.展开更多
Ceramic coatings were fabricated on aluminum doped with different concentrations of TiO2 nano-additive. alloy substrates by micro-arc oxidation （MAO） in silicate electrolytes Effects of nano-additive concentration o...Ceramic coatings were fabricated on aluminum doped with different concentrations of TiO2 nano-additive. alloy substrates by micro-arc oxidation （MAO） in silicate electrolytes Effects of nano-additive concentration on the structural and mechanical properties of the MAO coatings were analyzed. The results revealed that some nano-particle were incorporated into the resulting coating during the MAO process, while there was a reasonable concentration for the TiO2 nano-additive. With increasing the nano-additive concentration to 3.2 g/L, the adhesion value increased, while mean friction coefficient and mass loss decreased. A further increase of nano-additive deteriorated the adhesion and mean friction coefficient values, which was consistent with the micro-hardness tests.展开更多
Polytetrafluoroethylene(PTFE)has been widely used as a lubrication additive for reducing friction and wear;however,the hydrophobic nature of PTFE restricts its application in eco-friendly water-based lubrication syste...Polytetrafluoroethylene(PTFE)has been widely used as a lubrication additive for reducing friction and wear;however,the hydrophobic nature of PTFE restricts its application in eco-friendly water-based lubrication systems.In this study,for the first time,we designed novel PTFE@silica Janus nanoparticles(JNs)to meet the requirement for additives in water-based lubricants,which have excellent dispersion stability in water attributed to the unique amphiphilic structure.By introducing the lubrication of the aqueous dispersion of the JNs with a concentration of 0.5 wt%,the coefficient of friction(COF)and wear volume were reduced by 63.8%and 94.2%,respectively,comparing to those with the lubrication of pure water.Meanwhile,the JNs suspension also exhibits better lubrication and wear-resistance performances comparing to commercial silica and PTFE suspensions.The excellent tribological behaviors of PTFE@silica JNs as nano-additives could be attributed to the synergetic effect of the two components,where the PTFE provided lubrication through the formed tribofilms on the friction pairs,and the rigid silica further enhanced the wear-resistance performance.Most importantly,the unique structure of JNs makes it possible to use PTFE as an additive in water-lubrication systems.Our study shed light on the design and application of novel JNs nanomaterials as additives to meet the requirements of future industrial applications.展开更多
Ceramic coatings were prepared on AZ91 D Mg alloy by micro-arc oxidation （MAO） in aluminate electrolytes, with Al2O3 nano-additive suspending at different concentrations. Effects of nano-additive concentration on th...Ceramic coatings were prepared on AZ91 D Mg alloy by micro-arc oxidation （MAO） in aluminate electrolytes, with Al2O3 nano-additive suspending at different concentrations. Effects of nano-additive concentration on the structure, phase composition, hardness and anti-corrosion property of the MAO coatings were analyzed by scanning electron microscopy, X-ray diffraction, micro-hardness test and electrochemical method, respectively. The results revealed that Al2O3 nano-particles were mostly incorporated into ceramic coating chemically, transferred into MgAl2O4, rather than being trapped mechanically during MAO process. With the increase of Al2O3 concentration, the voltage-time response, content of MgAl2O4, hardness and anti-corrosion property increased. However, when the concentration varied from 10 g/L to 15 g/L, these behaviors and properties changed only a little. This result indicated that, after the concentration of Al2O3 nano-additive reaching 10 g/L, the incorporation of Al2O3 nano-particles turned into a saturation state, due to the complex process during MAO treatment. Therefore, 10 g/L might be a proper concentration for MAO coating to incorporate Al2O3 nano-particles,展开更多
This paper presents research findings on the tribological performance of electrodeposited coatings subject to nano-lubricants with the addition of nano-Al2O3 and graphene and Ni/nano-Al2O3 composite coatings. Electrod...This paper presents research findings on the tribological performance of electrodeposited coatings subject to nano-lubricants with the addition of nano-Al2O3 and graphene and Ni/nano-Al2O3 composite coatings. Electrodeposited coatings were produced by using a pulse electrodeposition method. Tribological experiments were conducted by using a linear reciprocating ball on fiat sliding tribometer. Experimental results confirmed that the wear and friction resistance properties were significantly enhanced by doping of nano-effects in the lubricating oil and composite coating. The addition of Al2O3 nanoparticles in the lubricating oil showed the best tribological properties, followed by Ni-Al2O3 composite coatings and nano-oil with graphene. The surface morphology and microstructure of electrodeposited coatings were examined by scanning electron microscopy, energy-dispersive spectroscopy and X-ray diffraction. The wear mechanisms of these coatings subjected to tribological testing were investigated by post-test surface analyses. This research provides a novel approach to design durable nano-coatings for tribological applications in various industries such as automotive, aerospace, locomotive and renewable energy technologies.展开更多
Surface of TiO2 nanoparticles was modified with the in situ chemical oxidative polymerization of aniline. Polyaniline modified TiO2 nanoparticles （PANI-TiO2） were characterized with the FT-IR, XRD, SEM and TEM techn...Surface of TiO2 nanoparticles was modified with the in situ chemical oxidative polymerization of aniline. Polyaniline modified TiO2 nanoparticles （PANI-TiO2） were characterized with the FT-IR, XRD, SEM and TEM techniques. Results confirmed that PANI was grafted successfully on the surface of TiO2 nanoparticles, therefore agglomeration of nanoparticles decreased dramatically. Polyvinyl chloride nanocomposites filled with 1 wt%-5 wt% of PANI-TiO2 and TiO2 nanoparticles were prepared via the solution blending method. PVC nanocomposites were analyzed with FT-IR, XRD, SEM, TG/DTA, DSC and tensile test techniques. Effect of PANI as surface modifier of nanoparticles was discussed according to the final properties of PVC nanocomposites. Results demonstrated that deposition of PANI on the surface of TiO2 nanoparticles improved the interfacial adhesion between the constituents of nanocomposites, which resulted in better dispersion of nanoparticles in the PVC matrix. Also PVC/PANI-TiO2 nanocomposites showed higher thennal resistance, tensile strength and Young＇s modulus compared to those of unfilled PVC and PVC/TiO2 nanocomposites.展开更多
文摘Direct electroless Ni-P plating was done on AZ91D magnesium alloy by immersing magnesium AZ91D samples into a bath containing Nickel sulphate.The nucleation mechanism of Ni-P deposits on the AZ91D magnesium alloy in the presence of surfactants and nano-additives was studied by using SEM.The electroless Ni-P deposits were preferentially nucleated on the β Mg_(17)Al_(12) phase of AZ91D magnesium alloy.Ni-P coating was coated uniformly in the presence of surfactants.Effect of surfactant C-Tab with varying quantities was studied.Addition of surfactant C-Tab homogenized the Ni-P deposition on AZ91D magnesium alloy surface.The effect produced by surfactant C-Tab was maximum with minimum addition(1 g/l)of surfactant C-Tab further increase in the surfactant C-Tab quantity did not brought much changes in morphology.Effect of surfactant SLS was studied using SEM.Surfactant SLS when incorporated in small amounts(6 g/l and 12 g/l)only exerted a slight influence in Ni-P deposition on AZ91D alloy surface.However Ni-P deposition was more uniform and spread throughout the surface with the addition of SLS surfactant(18 g/l).Effect of nano additives Al_(2)O_(3),ZnO,SiO_(2) were studied.Nano additive Al_(2)O_(3) enhanced the deposition of Ni-P on AZ91D alloy when added in 0.6 g/l quantity.SiO_(2) addition also gave the same results.ZnO addition influenced the Ni-P deposition on AZ91D alloy positively.Ni-P surface coating was coated more uniform and spread throughout the surface with the addition of surfactants and nano-additives.
基金supported by the Russian Science Foundation(grant No.17-79-20218-P).
文摘The paper presents the results of a systematic study of the influence of nano-additives of various concentrations,average sizes and composition on the temperature dependence of the viscosity and rheological behavior of water-based drilling fluids.Typical compositions of drilling fluids,such as water suspensions of various clay solutions and gammaxan-based polymer solutions,were considered.Hydrophilic nanoparticles of silicon and aluminum oxides were used as nano-additives at concentrations ranging from 0.25 to 3 wt%.The average nanoparticle size varied from 10 to 151 nm.The temperature of drilling fluids varied from 25℃ to 80℃.It is shown that the addition of nanoparticles to drilling fluids leads to a significant change in their rheological properties depending on the temperature.It was found that with increasing temperature,the yield stress and consistency index of drilling fluids with nanoparticles increase,while the behavior index,on the contrary,decreases.This behavior depends on the size of the nanoparticles.As the particle size increases,their influence on the temperature dependence of the drilling fluids’viscosity increases.In general,it is shown that the addition of nanoparticles makes the viscosity of drilling fluid more stable with regard to the temperature.This is an essential fact for practical application.
文摘Ceramic coatings were fabricated on aluminum doped with different concentrations of TiO2 nano-additive. alloy substrates by micro-arc oxidation （MAO） in silicate electrolytes Effects of nano-additive concentration on the structural and mechanical properties of the MAO coatings were analyzed. The results revealed that some nano-particle were incorporated into the resulting coating during the MAO process, while there was a reasonable concentration for the TiO2 nano-additive. With increasing the nano-additive concentration to 3.2 g/L, the adhesion value increased, while mean friction coefficient and mass loss decreased. A further increase of nano-additive deteriorated the adhesion and mean friction coefficient values, which was consistent with the micro-hardness tests.
基金financially supported by the National Natural Science Foundation of China(No.52005287)Beijing Institute of Technology Research Fund Program for Young Scholars,the Tribology Science Fund of State Key Laboratory of Tribology(SKLT)in Advanced Equipment(No.SKLTKF21B14)the Fund of Key Laboratory of Advanced Materials of Ministry of Education(No.ADV21-4).
文摘Polytetrafluoroethylene(PTFE)has been widely used as a lubrication additive for reducing friction and wear;however,the hydrophobic nature of PTFE restricts its application in eco-friendly water-based lubrication systems.In this study,for the first time,we designed novel PTFE@silica Janus nanoparticles(JNs)to meet the requirement for additives in water-based lubricants,which have excellent dispersion stability in water attributed to the unique amphiphilic structure.By introducing the lubrication of the aqueous dispersion of the JNs with a concentration of 0.5 wt%,the coefficient of friction(COF)and wear volume were reduced by 63.8%and 94.2%,respectively,comparing to those with the lubrication of pure water.Meanwhile,the JNs suspension also exhibits better lubrication and wear-resistance performances comparing to commercial silica and PTFE suspensions.The excellent tribological behaviors of PTFE@silica JNs as nano-additives could be attributed to the synergetic effect of the two components,where the PTFE provided lubrication through the formed tribofilms on the friction pairs,and the rigid silica further enhanced the wear-resistance performance.Most importantly,the unique structure of JNs makes it possible to use PTFE as an additive in water-lubrication systems.Our study shed light on the design and application of novel JNs nanomaterials as additives to meet the requirements of future industrial applications.
文摘Ceramic coatings were prepared on AZ91 D Mg alloy by micro-arc oxidation （MAO） in aluminate electrolytes, with Al2O3 nano-additive suspending at different concentrations. Effects of nano-additive concentration on the structure, phase composition, hardness and anti-corrosion property of the MAO coatings were analyzed by scanning electron microscopy, X-ray diffraction, micro-hardness test and electrochemical method, respectively. The results revealed that Al2O3 nano-particles were mostly incorporated into ceramic coating chemically, transferred into MgAl2O4, rather than being trapped mechanically during MAO process. With the increase of Al2O3 concentration, the voltage-time response, content of MgAl2O4, hardness and anti-corrosion property increased. However, when the concentration varied from 10 g/L to 15 g/L, these behaviors and properties changed only a little. This result indicated that, after the concentration of Al2O3 nano-additive reaching 10 g/L, the incorporation of Al2O3 nano-particles turned into a saturation state, due to the complex process during MAO treatment. Therefore, 10 g/L might be a proper concentration for MAO coating to incorporate Al2O3 nano-particles,
文摘This paper presents research findings on the tribological performance of electrodeposited coatings subject to nano-lubricants with the addition of nano-Al2O3 and graphene and Ni/nano-Al2O3 composite coatings. Electrodeposited coatings were produced by using a pulse electrodeposition method. Tribological experiments were conducted by using a linear reciprocating ball on fiat sliding tribometer. Experimental results confirmed that the wear and friction resistance properties were significantly enhanced by doping of nano-effects in the lubricating oil and composite coating. The addition of Al2O3 nanoparticles in the lubricating oil showed the best tribological properties, followed by Ni-Al2O3 composite coatings and nano-oil with graphene. The surface morphology and microstructure of electrodeposited coatings were examined by scanning electron microscopy, energy-dispersive spectroscopy and X-ray diffraction. The wear mechanisms of these coatings subjected to tribological testing were investigated by post-test surface analyses. This research provides a novel approach to design durable nano-coatings for tribological applications in various industries such as automotive, aerospace, locomotive and renewable energy technologies.
基金financially supported by the University of Tabriz
文摘Surface of TiO2 nanoparticles was modified with the in situ chemical oxidative polymerization of aniline. Polyaniline modified TiO2 nanoparticles （PANI-TiO2） were characterized with the FT-IR, XRD, SEM and TEM techniques. Results confirmed that PANI was grafted successfully on the surface of TiO2 nanoparticles, therefore agglomeration of nanoparticles decreased dramatically. Polyvinyl chloride nanocomposites filled with 1 wt%-5 wt% of PANI-TiO2 and TiO2 nanoparticles were prepared via the solution blending method. PVC nanocomposites were analyzed with FT-IR, XRD, SEM, TG/DTA, DSC and tensile test techniques. Effect of PANI as surface modifier of nanoparticles was discussed according to the final properties of PVC nanocomposites. Results demonstrated that deposition of PANI on the surface of TiO2 nanoparticles improved the interfacial adhesion between the constituents of nanocomposites, which resulted in better dispersion of nanoparticles in the PVC matrix. Also PVC/PANI-TiO2 nanocomposites showed higher thennal resistance, tensile strength and Young＇s modulus compared to those of unfilled PVC and PVC/TiO2 nanocomposites.
