The topic of superlubricity is attracting considerable interest around the world while humanity is facing an energy crisis.Since various liquid superlubricity systems can be commonly achieved on the macroscale in ambi...The topic of superlubricity is attracting considerable interest around the world while humanity is facing an energy crisis.Since various liquid superlubricity systems can be commonly achieved on the macroscale in ambient conditions,it is considered an effective solution to reduce unnecessary energy and material losses.However,certain practical problems such as low load-bearing pressure,dependence on hydrogen ions,and relatively long running-in processes still limit its widespread application.Two-dimensional(2D)nano-additives with ultrathin longitudinal dimensions can lower the shear resistance between sliding solid surfaces,and thus further optimize the applied conditions.In this review,the latest studies on 2D nano-additives with a combination of various water-based lubricants in the state of superlubricity are reported,typically including black phosphorus(BP),graphene oxide(GO),and layered double hydroxide.During the sliding process,composite lubricants effectively improved the load capacity(up to 600 MPa),reduced wear,and accelerated the running-in period(within 1,000 s)of the liquid superlubricity system.Both macromechanical experiments and microscopic tests are conducted to precisely analyze various interactions at the interfaces of the nano-additives and solid surfaces.These interactions can be described as tribochemical reactions,physical protection,and adsorption enhancement,and improved wear resistance.This review provides better guidance for applying 2D nanomaterials in liquid superlubricity systems.展开更多
Although metal-organic frameworks(MOFs)show numerous advantages over other crystalline materials,their industrial relevances have been impeded owing to their many drawbacks such as environmental impacts and economic c...Although metal-organic frameworks(MOFs)show numerous advantages over other crystalline materials,their industrial relevances have been impeded owing to their many drawbacks such as environmental impacts and economic costs of their synthesis.A green preparation pathway could greatly reduce the environmental costs,energy,and the need for toxic organic solvents,and consequently reduce the production cost.Thus,the most desirable synthesis route is the replacement of harsh organic solvents with aqueous solutions to abate environmental and economic impacts.This review summarizes recent research advancements of water-based routes for MOF synthesis and gives a brief outline of the most prominent examples.The challenges and prospects of the commercialization of promising MOFs in the future are also presented.This study aims to offer necessary information regarding the green,sustainable,and industrially acceptable fabrication of MOFs for their commercial applications in the future.展开更多
The poly (N-isopropylacrylamide) brush was covalently bonded on an initiator-coated silicon wafer via surface-initiated atom transfer radical polymerization. The polymer brush was (76.2±0.1) nm in thickness (by e...The poly (N-isopropylacrylamide) brush was covalently bonded on an initiator-coated silicon wafer via surface-initiated atom transfer radical polymerization. The polymer brush was (76.2±0.1) nm in thickness (by ellipsometer) with a grafting density of ca. 0.27 chains/nm 2 . The tribological properties of the poly (N-isopropylacrylamide) brush were investigated by means of ball-on-disk tests in a rotational mode under water lubrication for tribological application. The experimental results exhibited a low friction coefficient of ca. 0.03. The excellent lubrication property of the brush was due to its amide groups in the polymer chains. It was supposed that the good lubrication property of the brush was attributed to the cross-linked polymer network formed by the hydrogen bond association of N-H…O==C and the water molecular layer adsorbed by the terminal amide groups in the brush. The poly (N-isopropylacrylamide) solution also exhibits a lubrication property due to physical adsorption of the polymer chains.展开更多
To maintain tight control over rheological properties of high-density water-based drilling fluids, it is essential to understand the factors influencing the theology of water-based drilling fluids. This paper examines...To maintain tight control over rheological properties of high-density water-based drilling fluids, it is essential to understand the factors influencing the theology of water-based drilling fluids. This paper examines temperature effects on the rheological properties of two types of high-density water-based drilling fluids （fresh water-based and brine-based） under high temperature and high pressure （HTHP） with a Fann 50SL rheometer. On the basis of the water-based drilling fluid systems formulated in laboratory, this paper mainly describes the influences of different types and concentration of clay, the content of a colloid stabilizer named GHJ-1 and fluid density on the rheological parameters such as viscosity and shear stress. In addition, the effects of aging temperature and aging time of the drilling fluid on these parameters were also examined. Clay content and proportions for different densities of brine-based fluids were recommended to effectively regulate the rheological properties. Four theological models, the Bingham, power law, Casson and H-B models, were employed to fit the rheological parameters. It turns out that the H-B model was the best one to describe the rheological properties of the high-density drilling fluid under HTHP conditions and power law model produced the worst fit. In addition, a new mathematical model that describes the apparent viscosity as a function of temperature and pressure was established and has been applied on site.展开更多
It is necessary to modify the running-in process for the application of ceramics using water as a lubricant in real conditions because ceramics sliding in water are characterized by a running-in period with severe fri...It is necessary to modify the running-in process for the application of ceramics using water as a lubricant in real conditions because ceramics sliding in water are characterized by a running-in period with severe friction and wear.Fullerenol,a kind of highly water-soluble nanoparticle,was synthesized and then used to ameliorate the tribological properties of Si 3 N 4 sliding against Al 2 O 3 in pure water.With the addition of fullerenol,the running-in period was shortened from 30 min to 100 s at a speed of 250 mm/s.The speed threshold above which ultralow friction can be obtained in a short time was expanded from 450 mm/s to 80 mm/s.Meanwhile,the load-carrying ability of water film was increased.The role of fullerenol was discussed based on observation of the wear scar by an optical interferometer and XPS characterization of the tribo-film on the wear track.展开更多
Inkjet printing is a promising alternative for the fabrication of thin film components for solid oxide fuel cells(SOFCs) due to its contactless, mask free, and controllable printing process. In order to obtain satisfy...Inkjet printing is a promising alternative for the fabrication of thin film components for solid oxide fuel cells(SOFCs) due to its contactless, mask free, and controllable printing process. In order to obtain satisfying electrolyte thin layer structures in anode-supported SOFCs, the preparation of suitable electrolyte ceramic inks is a key. At present, such a kind of 8 mol% Y_(2)O_(3)-stabilized ZrO_(2)(8 YSZ) electrolyte ceramic ink with long-term stability and high solid loading(> 15 wt%) seems rare for precise inkjet printing, and a number of characterization and performance aspects of the inks, such as homogeneity, viscosity, and printability, should be studied. In this study, 8 YSZ ceramic inks of varied compositions were developed for inkjet printing of SOFC ceramic electrolyte layers. The dispersing effect of two types of dispersants, i.e., polyacrylic acid ammonium(PAANH4) and polyacrylic acid(PAA), were compared. The results show that ultrasonic dispersion treatment can help effectively disperse the ceramic particles in the inks. PAANH4 has a better dispersion effect for the inks developed in this study. The inks show excellent printable performance in the actual printing process. The stability of the ink can be maintained for a storage period of over 30 days with the help of initial ultrasonic dispersion. Finally, micron-size thin 8 YSZ electrolyte films were successfully fabricated through inkjet printing and sintering, based on the as-developed high solid loading 8 YSZ inks(20 wt%). The films show fully dense and intact structural morphology and smooth interfacial bonding, offering an improved structural quality of electrolyte for enhanced SOFC performance.展开更多
基金the National Natural Science Foundation of China(51905294,51527901,and 51875303)the China Postdoc Innovation Talent Support Program(BX20180168)the China Postdoctoral Science Foundation(2019M650654)。
文摘The topic of superlubricity is attracting considerable interest around the world while humanity is facing an energy crisis.Since various liquid superlubricity systems can be commonly achieved on the macroscale in ambient conditions,it is considered an effective solution to reduce unnecessary energy and material losses.However,certain practical problems such as low load-bearing pressure,dependence on hydrogen ions,and relatively long running-in processes still limit its widespread application.Two-dimensional(2D)nano-additives with ultrathin longitudinal dimensions can lower the shear resistance between sliding solid surfaces,and thus further optimize the applied conditions.In this review,the latest studies on 2D nano-additives with a combination of various water-based lubricants in the state of superlubricity are reported,typically including black phosphorus(BP),graphene oxide(GO),and layered double hydroxide.During the sliding process,composite lubricants effectively improved the load capacity(up to 600 MPa),reduced wear,and accelerated the running-in period(within 1,000 s)of the liquid superlubricity system.Both macromechanical experiments and microscopic tests are conducted to precisely analyze various interactions at the interfaces of the nano-additives and solid surfaces.These interactions can be described as tribochemical reactions,physical protection,and adsorption enhancement,and improved wear resistance.This review provides better guidance for applying 2D nanomaterials in liquid superlubricity systems.
基金support from the National Natural Science Foundation of China(21576094,21776097 and 51678245)Guangdong Natural Science Foundation(2017A030313052 and 2019A1515011121)+1 种基金Guangzhou Science&Technology Project(201804010219)the Fundamental Research Funds for the Central Universities.
文摘Although metal-organic frameworks(MOFs)show numerous advantages over other crystalline materials,their industrial relevances have been impeded owing to their many drawbacks such as environmental impacts and economic costs of their synthesis.A green preparation pathway could greatly reduce the environmental costs,energy,and the need for toxic organic solvents,and consequently reduce the production cost.Thus,the most desirable synthesis route is the replacement of harsh organic solvents with aqueous solutions to abate environmental and economic impacts.This review summarizes recent research advancements of water-based routes for MOF synthesis and gives a brief outline of the most prominent examples.The challenges and prospects of the commercialization of promising MOFs in the future are also presented.This study aims to offer necessary information regarding the green,sustainable,and industrially acceptable fabrication of MOFs for their commercial applications in the future.
基金supported by the National Natural Science Foundation of China (Grant Nos. 50805086 and 50730007)the Foundation for Innovative Research Groups of the National Natural Science Foundation of China (Grant No. 51021064)
文摘The poly (N-isopropylacrylamide) brush was covalently bonded on an initiator-coated silicon wafer via surface-initiated atom transfer radical polymerization. The polymer brush was (76.2±0.1) nm in thickness (by ellipsometer) with a grafting density of ca. 0.27 chains/nm 2 . The tribological properties of the poly (N-isopropylacrylamide) brush were investigated by means of ball-on-disk tests in a rotational mode under water lubrication for tribological application. The experimental results exhibited a low friction coefficient of ca. 0.03. The excellent lubrication property of the brush was due to its amide groups in the polymer chains. It was supposed that the good lubrication property of the brush was attributed to the cross-linked polymer network formed by the hydrogen bond association of N-H…O==C and the water molecular layer adsorbed by the terminal amide groups in the brush. The poly (N-isopropylacrylamide) solution also exhibits a lubrication property due to physical adsorption of the polymer chains.
文摘To maintain tight control over rheological properties of high-density water-based drilling fluids, it is essential to understand the factors influencing the theology of water-based drilling fluids. This paper examines temperature effects on the rheological properties of two types of high-density water-based drilling fluids （fresh water-based and brine-based） under high temperature and high pressure （HTHP） with a Fann 50SL rheometer. On the basis of the water-based drilling fluid systems formulated in laboratory, this paper mainly describes the influences of different types and concentration of clay, the content of a colloid stabilizer named GHJ-1 and fluid density on the rheological parameters such as viscosity and shear stress. In addition, the effects of aging temperature and aging time of the drilling fluid on these parameters were also examined. Clay content and proportions for different densities of brine-based fluids were recommended to effectively regulate the rheological properties. Four theological models, the Bingham, power law, Casson and H-B models, were employed to fit the rheological parameters. It turns out that the H-B model was the best one to describe the rheological properties of the high-density drilling fluid under HTHP conditions and power law model produced the worst fit. In addition, a new mathematical model that describes the apparent viscosity as a function of temperature and pressure was established and has been applied on site.
基金supported by the National Natural Science Foundation of China (Grant Nos. 50805086 and 50730007)the Foundation for Innovative Research Groups of the National Natural Science Foundation of China (Grant Nos. 51021064 and 20821003)the National Basic Research Program of China (973 Program) (Grant No.2011CB302100)
文摘It is necessary to modify the running-in process for the application of ceramics using water as a lubricant in real conditions because ceramics sliding in water are characterized by a running-in period with severe friction and wear.Fullerenol,a kind of highly water-soluble nanoparticle,was synthesized and then used to ameliorate the tribological properties of Si 3 N 4 sliding against Al 2 O 3 in pure water.With the addition of fullerenol,the running-in period was shortened from 30 min to 100 s at a speed of 250 mm/s.The speed threshold above which ultralow friction can be obtained in a short time was expanded from 450 mm/s to 80 mm/s.Meanwhile,the load-carrying ability of water film was increased.The role of fullerenol was discussed based on observation of the wear scar by an optical interferometer and XPS characterization of the tribo-film on the wear track.
基金supported by the National Natural Science Foundation of China (51975384)Guangdong Basic and Applied Basic Research Foundation (2020A1515011547)+1 种基金Natural Science Foundation of Shenzhen (JCYJ20190808144009478)Key-Area Research and Development Program of Guangdong Province (2020B090924003)。
文摘Inkjet printing is a promising alternative for the fabrication of thin film components for solid oxide fuel cells(SOFCs) due to its contactless, mask free, and controllable printing process. In order to obtain satisfying electrolyte thin layer structures in anode-supported SOFCs, the preparation of suitable electrolyte ceramic inks is a key. At present, such a kind of 8 mol% Y_(2)O_(3)-stabilized ZrO_(2)(8 YSZ) electrolyte ceramic ink with long-term stability and high solid loading(> 15 wt%) seems rare for precise inkjet printing, and a number of characterization and performance aspects of the inks, such as homogeneity, viscosity, and printability, should be studied. In this study, 8 YSZ ceramic inks of varied compositions were developed for inkjet printing of SOFC ceramic electrolyte layers. The dispersing effect of two types of dispersants, i.e., polyacrylic acid ammonium(PAANH4) and polyacrylic acid(PAA), were compared. The results show that ultrasonic dispersion treatment can help effectively disperse the ceramic particles in the inks. PAANH4 has a better dispersion effect for the inks developed in this study. The inks show excellent printable performance in the actual printing process. The stability of the ink can be maintained for a storage period of over 30 days with the help of initial ultrasonic dispersion. Finally, micron-size thin 8 YSZ electrolyte films were successfully fabricated through inkjet printing and sintering, based on the as-developed high solid loading 8 YSZ inks(20 wt%). The films show fully dense and intact structural morphology and smooth interfacial bonding, offering an improved structural quality of electrolyte for enhanced SOFC performance.
