Non-thermal plasmas under atmospheric pressure are of great interest in polymer surface processing because of their convenience, effectiveness and low cost. In this paper, the treatment of Polyethylene terephthalate (...Non-thermal plasmas under atmospheric pressure are of great interest in polymer surface processing because of their convenience, effectiveness and low cost. In this paper, the treatment of Polyethylene terephthalate (PET) film surface for improving hydrophilicity using the non-thermal plasma generated by atmospheric pressure glow discharge (APGD) in air is conducted. The discharge characteristics of APGD are shown by measurement of their electrical discharge parameters and observation of light-emission phenomena, and the surface properties of PET before and after the APGD treatment are studied using contact angle measurement, x-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). It is found that the APGD is homogeneous and stable in the whole gas gap, which differs from the commonly filamentary dielectric barrier discharge (DBD). A short time (several seconds) APGD treatment can modify the surface characteristics of PET film markedly and uniformly. After 10 s APGD treatment, the展开更多
Nanosecond-pulse diffuse discharges could provide high-density plasma and high-energy electrons at atmospheric pressure. In this paper, the surface treatment of Cu by nanosecond-pulse diffuse discharges is conducted i...Nanosecond-pulse diffuse discharges could provide high-density plasma and high-energy electrons at atmospheric pressure. In this paper, the surface treatment of Cu by nanosecond-pulse diffuse discharges is conducted in atmospheric air. Factors influencing the water contact angle （WCA）, chemical composition and microhardness, such as the gap spacing and treatment time, are investigated. The results show that after the plasma surface treatment, the WCA considerably decreases from 87~ to 42.3~, and the surface energy increases from 20.46 mJ m-2 to 66.28 mJ m-2. Results of energy dispersive x-ray analysis show that the concentration of carbon decreases, but the concentrations of oxygen and nitrogen increase significantly. Moreover, the microhardness increases by approximately 30% after the plasma treatment. The aforementioned changes on the Cu surface indicate the plasma surface treatment enhances the hydrophilicity and microhardness, and it cleans the carbon and achieves oxidization on the Cu surface. Furthermore, by increasing the gap spacing and treatment time, better treatment effects can be obtained. The micmhardness in the case of a 2.5 cm gap is higher than that in the case of a 3 cm gap. More oxygen and nitrogen species appear on the Cu surface for the 2.5 cm gap treatment than for the 3 cm gap treatment. The WCA significantly decreases with the treatment thne when it is no longer than 90 s, and then it reaches saturation. In addition, more oxygen-containing and nitrogen-containing groups appear after extended plasma treatment time. They contribute to the improvement of the hydrophilicity and oxidation on the Cu surface.展开更多
Titanium dioxide(Ti O_(2))nanopowder(P-25;Degussa AG)was treated using dielectric barrier discharge(DBD)in a rotary electrode DBD(RE-DBD)reactor.Its electrical and optical characteristics were investigated during RE-D...Titanium dioxide(Ti O_(2))nanopowder(P-25;Degussa AG)was treated using dielectric barrier discharge(DBD)in a rotary electrode DBD(RE-DBD)reactor.Its electrical and optical characteristics were investigated during RE-DBD generation.The treated TiO_(2)nanopowder properties and structures were analyzed using x-ray diffraction(XRD)and Fourier-transform infrared spectroscopy(FTIR).After RE-DBD treatment,XRD measurements indicated that the anatase peak theta positions shifted from 25.3°to 25.1°,which can be attributed to the substitution of new functional groups in the TiO_(2)lattice.The FTIR results show that hydroxyl groups(OH)at 3400 cm-1 increased considerably.The mechanism used to modify the TiO_(2)nanopowder surface by air DBD treatment was confirmed from optical emission spectrum measurements.Reactive species,such as OH radical,ozone and atomic oxygen can play key roles in hydroxyl formation on the TiO_(2)nanopowder surface.展开更多
Atmospheric pressure non-thermal plasma is of interest for industrial applications. In this study, polypropylene （PP） films are modified by a dielectric barrier discharge （DBD） with a non-uniform magnetic field in...Atmospheric pressure non-thermal plasma is of interest for industrial applications. In this study, polypropylene （PP） films are modified by a dielectric barrier discharge （DBD） with a non-uniform magnetic field in air at atmospheric pressure. The surface properties of the PP films before and after a DBD treatment are studied by using contact angle measurement, atomic force microscopy （AFM） and X-ray photoelectron spectroscopy （XPS）. The effect of treatment time on the surface modification with and without a magnetic field is investigated. It is found that the hydrophilic improvement depends on the treatment time and magnetic field. It is also found that surface roughness and oxygen-containing groups are introduced onto the PP film surface after the DBD treatment. Surface roughness and oxygen-containing polar functional groups of the PP films increase with the magnetic induction density. The functional groups are identified as C-O, C=O and O-C=O by using XPS analysis. It is concluded that the hydrophilic improvement of PP films treated with a magnetic field is due to a greater surface roughness and more oxygen-containing groups.展开更多
To reduce time and energy during thermal binder removal in the ceramic process, plasma surface treatment was applied before the lamination process.The adhesion strength in the lamination films was enhanced by oxidativ...To reduce time and energy during thermal binder removal in the ceramic process, plasma surface treatment was applied before the lamination process.The adhesion strength in the lamination films was enhanced by oxidative plasma treatment of the porous green ceramic film with polymeric binding materials.The oxygen plasma characteristics were investigated through experimental parameters and weight loss analysis.The experimental results revealed the need for parameter analysis,including gas material,process time,flow rate,and discharge power,and supported a mechanism consisting of competing ablation and deposition processes.The weight loss analysis was conducted for cyclic plasma treatment rather than continuous plasma treatment for the purpose of improving the film’s permeability by suppressing deposition of the ablated species.The cyclic plasma treatment improved the permeability compared to the continuous plasma treatment.展开更多
A radio frequency argon plasma reactor with a stirrer was employed for the surface treatment of polypropylene （PP） powders. The changes in the superficial contact angle and the superficial composition of the un-trea...A radio frequency argon plasma reactor with a stirrer was employed for the surface treatment of polypropylene （PP） powders. The changes in the superficial contact angle and the superficial composition of the un-treated and treated PP powders were analyzed by means of water contact angle （WCA） measurement, X-ray photoelectron spectroscopy （XPS） and attenuated total reflection Fourier transform infrared spectroscopy （ATR-FTIR）. The water contact angle changed from the original value of 130.2° before plasma treatment to the value of 73.6° after treatment for 5 minutes. With the increase in plasma treating time, there were a decrease in the water contact angle and an increase in the content of oxygen containing polar functional groups （i.e., C-O, C=O and O-C=O）. Both XPS and ATR-FTIR results indicated that the plasma treatment led to the formation of oxygen containing polar functional groups due to oxidation on the surface of the PP powders, and the trend of variation of the water contact angle with plasma treating time was related to the concentration of oxygen atom on the treated PP powders surface. Furthermore, the aging of the plasma-treated PP powders was investigated.展开更多
Polyethylenimine(PEI) interlayer rinsing with different solvents for inverted organic light emitting diodes(OLEDs)is systematically studied in this paper. In comparison with the pristine one, the maximum current effic...Polyethylenimine(PEI) interlayer rinsing with different solvents for inverted organic light emitting diodes(OLEDs)is systematically studied in this paper. In comparison with the pristine one, the maximum current efficiency(CE) and power efficiency(PE) are enhanced by 21% and 22% for the device rinsing by ethylene glycol monomethyl ether(EEA).Little effect is found on the work function of the PEI interlayer rinsed by deionized water(DI), ethanol(EtOH), and EEA.On the other hand, the surface morphologies of PEI through different solvent treatments are quite different. Our results indicates that the surface morphology is the key to improving the device performance for IOLED as the work function of PEI keeps stable.展开更多
To form low-resistance Ohmic contact to p-type GaN, InGaN/GaN multiple quantum well light emitting diode wafers are treated with boiled aqua regia prior to Ni/Au （5 nm/5 nm） film deposition. The surface morphology o...To form low-resistance Ohmic contact to p-type GaN, InGaN/GaN multiple quantum well light emitting diode wafers are treated with boiled aqua regia prior to Ni/Au （5 nm/5 nm） film deposition. The surface morphology of wafers and the current voltage characteristics of fabricated light emitting diode devices are investigated. It is shown that surface treatment with boiled aqua regia could effectively remove oxide from the surface of the p-GaN layer, and reveal defect-pits whose density is almost the same as the screw dislocation density estimated by x-ray rocking curve measurement. It suggests that the metal atoms of the Ni/Au transparent electrode of light emitting diode devices may diffuse into the p-GaN layer along threading dislocation lines and form additional leakage current channels. Therefore, the surface treatment time with boiled aqua regia should not be too long so as to avoid the increase of threading dislocation-induced leakage current and the degradation of electrical properties of light emitting diodes.展开更多
In this study,a high-density polyethylene（HDPE,5-mm-thick,0.95 g/cm3） surface was treated using an RF capacitive atmospheric pressure cold Ar plasma jet.By using this Ar plasma jet,a hydrophilic HDPE surface was for...In this study,a high-density polyethylene（HDPE,5-mm-thick,0.95 g/cm3） surface was treated using an RF capacitive atmospheric pressure cold Ar plasma jet.By using this Ar plasma jet,a hydrophilic HDPE surface was formed during the plasma treatment.In particular, the effects of an additive gas（N;or O2） on the HDPE surface treatment were investigated in detail.It was shown that the addition of N2 or O2 gas had an important influence on the HDPE surface treatment.Compared to pure Ar plasma treatment,a lower value of water contact angle （WCA） was obtained when a trace of N2 or O2 gas was added.It was also found that besides the quantities of active species in the plasma jet,the treatment temperature played an important role in the HDPE surface treatment.This is because surface molecular motion is not negligible when the treatment temperature is close to the melting point of the polymer.展开更多
Based on the structure,working principle,and working conditions of conductance water cut sensor,it is revealed that the early failure of the metal electrode of the sensor is due to the comprehensive influence of well ...Based on the structure,working principle,and working conditions of conductance water cut sensor,it is revealed that the early failure of the metal electrode of the sensor is due to the comprehensive influence of well fluid erosion,electrochemical corrosion,and oil pollution during its long-term service in the downhole.A technology for electrode surface treatment is proposed using boron-doped diamond(BDD)films to improve the service performance of the modified electrode.The hot wire chemical vapor deposition method was adopted to fabricate BDD film,the boron doping concentration and deposition time were optimized,and fluorination treatment was applied to improve the wear resistance,electrochemical corrosion resistance,and oleophobic property of the BDD film comprehensively.The results showed that BDD film with boron doping concentration of 6×10^(-3) exhibited high wear resistance and good electrochemical corrosion resistance,and endowed the modified electrode with superior erosion resistance and corrosion resistance.The friction coefficient and wear rate of BDD modified electrode were 92%and 78%lower than those of Invar alloy,also,the low-frequency impedance modulus value of the modified electrode was higher than 1×10^(4) Ω·cm^(2).The BDD film prepared with a deposition time of 8 h had a favorable micro-nano structure owing to small grain size and uniform distribution.Such morphology was conducive to enhancing the oleophobic performance of the modified electrode,and its contact angle in the simulated well fluid was high to 102°.The engineering applicability of BDD film modified electrode under simulated working conditions indicated that,the modified electrode had excellent comprehensive performances of erosion resistance,electrochemical corrosion resistance and oil adhesion resistance,and can realize the long-term stable operation of the conductance water cut sensor under harsh downhole conditions.展开更多
The polymer treatment with a low-temperature plasma jet generated on the atmospheric pressure surface discharge （SD） plasma is performed. The change of the surface property over time, in comparison with low pressure...The polymer treatment with a low-temperature plasma jet generated on the atmospheric pressure surface discharge （SD） plasma is performed. The change of the surface property over time, in comparison with low pressure oxygen （O2） plasma treatment, is examined. As one compares the treatment by atmospheric pressure plasma to that by the low pressure O2 plasma of PS （polystyrene） the treatment effects were almost in complete agreement. However, when the atmospheric pressure plasma was used for PP（polypropylene）, it produced remarkable hydrophilic effects.展开更多
This study aimed to evaluate the surface roughness and wetting properties of various dental prosthetic materials after different durations of non-thermal atmospheric plasma（NTAP）treatment.One hundred and sixty discs...This study aimed to evaluate the surface roughness and wetting properties of various dental prosthetic materials after different durations of non-thermal atmospheric plasma（NTAP）treatment.One hundred and sixty discs of titanium（Ti）（n：40）,cobalt chromium（Co-Cr）（n：40）,yttrium stabilized tetragonal zirconia polycrystals（Y-TZP）（n：40）and polymethylmethacrylate（PMMA）（n：40）materials were machined and smoothed with silicon carbide papers.The surface roughness was evaluated in a control group and in groups with different plasma exposure times [1-3-5 s].The average surface roughness（Ra）and contact angle（CA）measurements were recorded via an atomic force microscope（AFM）and tensiometer,respectively.Surface changes were examined with a scanning electron microscope（SEM）.Data were analyzed with two-way analysis of variance（ANOVA）and the Tukey HSD test α=0.05）.According to the results,the NTAP surface treatment significantly affected the roughness and wettability properties（P 〈 0.05）.SEM images reveal that more grooves were present in the NTAP groups.With an increase in the NTAP application time,an apparent increment was observed for Ra,except in the PMMA group,and a remarkable reduction in CA was observed in all groups.It is concluded that the NTAP technology could enhance the roughening and wetting performance of various dental materials.展开更多
Surface modifications can introduce natural gradients or structural hierarchy into human-made microlattices,making them simultaneously strong and tough.Herein,we describe our investigations of the mechanical propertie...Surface modifications can introduce natural gradients or structural hierarchy into human-made microlattices,making them simultaneously strong and tough.Herein,we describe our investigations of the mechanical properties and the underlying mechanisms of additively manufactured nickel–chromium superalloy(IN625)microlattices after surface mechanical attrition treatment(SMAT).Our results demonstrated that SMAT increased the yielding strength of these microlattices by more than 64.71%and also triggered a transition in their mechanical behaviour.Two primary failure modes were distinguished:weak global deformation,and layer-by-layer collapse,with the latter enhanced by SMAT.The significantly improved mechanical performance was attributable to the ultrafine and hard graded-nanograin layer induced by SMAT,which effectively leveraged the material and structural effects.These results were further validated by finite element analysis.This work provides insight into collapse behaviour and should facilitate the design of ultralight yet buckling-resistant cellular materials.展开更多
In this study, commercial biaxially oriented polypropylene （BOPP）, polyvinyl chlo- ride （PVC） and poly （methyl methacrylate） （PMMA） films were treated with nitrogen plasma over different exposure times in a Py...In this study, commercial biaxially oriented polypropylene （BOPP）, polyvinyl chlo- ride （PVC） and poly （methyl methacrylate） （PMMA） films were treated with nitrogen plasma over different exposure times in a Pyrex tube surrounded by a DC variable magnetic field. The chemi- cal changes that appeared on the surface of the samples were investigated using Fourier transform infrared （FT4R） spectroscopy and attenuated total reflectance Fourier transform infrared （ATR- FTIR） spectroscopy after treatment for 2 min, 4 min and 6 rain in a nitrogen plasma chamber. Effects of the plasma treatment on the surface topographies and contact angles of the untreated and plasma treated films were also analyzed by atomic force microscopy （AFM） and a contact angle measuring system. The results show that the plasma treated films become more hydrophilic with an enhanced wettability due to the formation of some new polar groups on the surface of the treated films. Moreover, at higher exposure times, the total surface energy in all treated films increased while a reduction in contact angle occurred. The behavior of surface roughness in each sample was completely different at higher exposure times.展开更多
Trichloroethylene （TCE） pretreatment of Si surface prior to HfO2 deposition is employed to fabricate HfO2 gatedielectric MOS capacitors. Influence of this processing procedure on interlayer growth, HfO2/Si interface...Trichloroethylene （TCE） pretreatment of Si surface prior to HfO2 deposition is employed to fabricate HfO2 gatedielectric MOS capacitors. Influence of this processing procedure on interlayer growth, HfO2/Si interface properties, gate-oxide leakage and device reliability is investigated. Among the surface pretreatments in NH3, NO, N2O and TCE ambients, the TCE pretreatment gives the least interlayer growths the lowest interface-state density, the smallest gate leakage and the highest reliability. All these improvements should be ascribed to the passivation effects of Cl2 and HC1 on the structural defects in the interlayer and at the interface, and also their gettering effects on the ion contamination in the gate dielectric.展开更多
This paper presents the results of aluminum surface treatment by diffuse coplanar surface barrier discharge. The goals are to study the effectiveness of the plasma treatment and the dependence of its efficiency on ope...This paper presents the results of aluminum surface treatment by diffuse coplanar surface barrier discharge. The goals are to study the effectiveness of the plasma treatment and the dependence of its efficiency on operation parameters, such as sample-to-electrode distance, treatment time or gas atmosphere. Three types of aluminum materials （bricks, sheets and thin films） were tested to ensure the reliability of the treatment. The changes in the surface properties were characterized by the surface free energy, atomic force microscopy, attenuated total reflectance Fourier transform infrared spectroscopy （ATR FTIR） and X-ray photoelectron spec- troscopy （XPS）. The influence of aging effect on the treatment was also measured and discussed.展开更多
Non-thermal plasmas under atmospheric pressure are of great interest in industrial applications, especially in material surface treatment. In this paper, the treatment of a glass surface for improving hydrophobicity u...Non-thermal plasmas under atmospheric pressure are of great interest in industrial applications, especially in material surface treatment. In this paper, the treatment of a glass surface for improving hydrophobicity using the non-thermal plasma generated by dielectric barrier discharge （DBD） at atmospheric pressure in ambient air is conducted, and the surface properties of the glass before and after the DBD treatment are studied by using contact angle measurement, surface resistance measurement and wet flashover voltage tests. The effects of the applied voltage and time duration of DBD on the surface modification are studied, and the optimal conditions for the treatment are obtained. It is found that a layer of hydrophobic coating is formed on the glass surface after spraying a thin layer of silicone oil and undergoing the DBD treatment, and the improvement of hydrophobicity depends on DBD voltage and treating time. It seems that there exists an optimum treating time for a certain applied voltage of DBD during the surface treatment, The test results of thermal aging and chemical aging show that the hydrophobic layer has quite stable characteristics. The interaction mechanism between the DBD plasma and the glass surface is discussed. It is concluded that CHa and large molecule radicals can react with the radicals in the glass surface to replace OH, and the hydrophobicity of the glass surface is improved accordingly.展开更多
A new surface strengthening technology, luster polish strengthening treatment, was proposed to treat the raceway surface of aeroengine bearings （9Cr18Mo） with the centrifugal strengthening machine exclusively design...A new surface strengthening technology, luster polish strengthening treatment, was proposed to treat the raceway surface of aeroengine bearings （9Cr18Mo） with the centrifugal strengthening machine exclusively designed for luster polish strengthening treatment. The experimental results showed that luster polish strengthening treatment produced a compressive residual stress layer with a depth of over 80 μm below the surface of the bearing raceway, and thus effectively removed the metamorphic layer in the raceway surface. After luster polish strengthening treatment, the average surface hardness of the aeroengine bearing raceway was increased from 61.02 HRC to 63.01 HRC, the surface roughness was reduced from 0.06 μm to 0.03 μm, and the contact fatigue life of the aeroengine bearings was improved by about 90%, with the dispersion of fatigue life being reduced remarkably. Theoretical calculation result agrees with that obtained by experiment.展开更多
Natural cellulose was treated by an atmospheidc DBD plasma. The solubility of cellulose in a diluted alkaline solution after the plasma treatment was investigated. The properties were characterized by X-ray photoelect...Natural cellulose was treated by an atmospheidc DBD plasma. The solubility of cellulose in a diluted alkaline solution after the plasma treatment was investigated. The properties were characterized by X-ray photoelectron spectroscopy （XPS）, Fourier-transform infrared spectroscopy （FTIR） and scanning electron microscopy （SEM）. The results indicated that the surface of cellulose treated by the argon DBD plasma was significantly etched, and the relevant force of hydrogen bonding was decreased. This might be the essential reason for the solubility improvement of natural cellulose in the diluted alkaline solution. Through a comparison of two discharge modes, the atmospheric DBD plasma gun and the parallel plate capacitively coupled DBD plasma, it was found that the atmospheric DBD plasma gun was more effective in fragmentizing the cellulose due to its production of a high energy plasma based on its special structure.展开更多
The characteristics of a low power 50 Hz argon plasma for surface treatment of polytetrafluoroethylene(PTFE)film is presented in this article.The current–voltage behavior of the discharge and time-varying intensity o...The characteristics of a low power 50 Hz argon plasma for surface treatment of polytetrafluoroethylene(PTFE)film is presented in this article.The current–voltage behavior of the discharge and time-varying intensity of the discharge showed that a DC glow discharge was generated in reversed polarity at every half-cycle.At discharge power between 0.5 and 1 W,the measured electron temperature and density were 2–3 eV and∼10^(8) cm^(−3),respectively.The optical emission spectrum of the argon plasma showed presence of some‘impurity species’such as OH,N_(2) and H,which presumably originated from the residual air in the discharge chamber.On exposure of PTFE films to the argon glow plasma at pressure 120 Pa and discharge power 0.5 to 1 W,the water contact angle reduced by 4%to 20%from the original 114°at pristine condition,which confirms improvement of its surface wettability.The increase in wettability was attributed to incorporation of oxygen-containing functional groups on the treated surface and concomitant reduction in fluorine as revealed by the XPS analysis and increase in surface roughness analyzed from the atomic force micrographs.Ageing upon storage in ambient air showed retention of the induced increase in surface wettability.展开更多
文摘Non-thermal plasmas under atmospheric pressure are of great interest in polymer surface processing because of their convenience, effectiveness and low cost. In this paper, the treatment of Polyethylene terephthalate (PET) film surface for improving hydrophilicity using the non-thermal plasma generated by atmospheric pressure glow discharge (APGD) in air is conducted. The discharge characteristics of APGD are shown by measurement of their electrical discharge parameters and observation of light-emission phenomena, and the surface properties of PET before and after the APGD treatment are studied using contact angle measurement, x-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). It is found that the APGD is homogeneous and stable in the whole gas gap, which differs from the commonly filamentary dielectric barrier discharge (DBD). A short time (several seconds) APGD treatment can modify the surface characteristics of PET film markedly and uniformly. After 10 s APGD treatment, the
基金partly supported by National Natural Science Foundation of China under Grant No. 51477164the National Basic Research Program of China under Grant No. 2014CB239505-03+1 种基金the State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources under Grant No. LAPS16013the Science and Technology Project of State Grid Corporation of China
文摘Nanosecond-pulse diffuse discharges could provide high-density plasma and high-energy electrons at atmospheric pressure. In this paper, the surface treatment of Cu by nanosecond-pulse diffuse discharges is conducted in atmospheric air. Factors influencing the water contact angle （WCA）, chemical composition and microhardness, such as the gap spacing and treatment time, are investigated. The results show that after the plasma surface treatment, the WCA considerably decreases from 87~ to 42.3~, and the surface energy increases from 20.46 mJ m-2 to 66.28 mJ m-2. Results of energy dispersive x-ray analysis show that the concentration of carbon decreases, but the concentrations of oxygen and nitrogen increase significantly. Moreover, the microhardness increases by approximately 30% after the plasma treatment. The aforementioned changes on the Cu surface indicate the plasma surface treatment enhances the hydrophilicity and microhardness, and it cleans the carbon and achieves oxidization on the Cu surface. Furthermore, by increasing the gap spacing and treatment time, better treatment effects can be obtained. The micmhardness in the case of a 2.5 cm gap is higher than that in the case of a 3 cm gap. More oxygen and nitrogen species appear on the Cu surface for the 2.5 cm gap treatment than for the 3 cm gap treatment. The WCA significantly decreases with the treatment thne when it is no longer than 90 s, and then it reaches saturation. In addition, more oxygen-containing and nitrogen-containing groups appear after extended plasma treatment time. They contribute to the improvement of the hydrophilicity and oxidation on the Cu surface.
文摘Titanium dioxide(Ti O_(2))nanopowder(P-25;Degussa AG)was treated using dielectric barrier discharge(DBD)in a rotary electrode DBD(RE-DBD)reactor.Its electrical and optical characteristics were investigated during RE-DBD generation.The treated TiO_(2)nanopowder properties and structures were analyzed using x-ray diffraction(XRD)and Fourier-transform infrared spectroscopy(FTIR).After RE-DBD treatment,XRD measurements indicated that the anatase peak theta positions shifted from 25.3°to 25.1°,which can be attributed to the substitution of new functional groups in the TiO_(2)lattice.The FTIR results show that hydroxyl groups(OH)at 3400 cm-1 increased considerably.The mechanism used to modify the TiO_(2)nanopowder surface by air DBD treatment was confirmed from optical emission spectrum measurements.Reactive species,such as OH radical,ozone and atomic oxygen can play key roles in hydroxyl formation on the TiO_(2)nanopowder surface.
基金supported by China Postdoctoral Science Foundation(No.20100480255)the Scientific Research Starting Foundation for Talent Introduction(Nanjing University of Information Science&Technology)
文摘Atmospheric pressure non-thermal plasma is of interest for industrial applications. In this study, polypropylene （PP） films are modified by a dielectric barrier discharge （DBD） with a non-uniform magnetic field in air at atmospheric pressure. The surface properties of the PP films before and after a DBD treatment are studied by using contact angle measurement, atomic force microscopy （AFM） and X-ray photoelectron spectroscopy （XPS）. The effect of treatment time on the surface modification with and without a magnetic field is investigated. It is found that the hydrophilic improvement depends on the treatment time and magnetic field. It is also found that surface roughness and oxygen-containing groups are introduced onto the PP film surface after the DBD treatment. Surface roughness and oxygen-containing polar functional groups of the PP films increase with the magnetic induction density. The functional groups are identified as C-O, C=O and O-C=O by using XPS analysis. It is concluded that the hydrophilic improvement of PP films treated with a magnetic field is due to a greater surface roughness and more oxygen-containing groups.
基金supported by Basic Science Research Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Education, Science and Technology(2011-0013211).
文摘To reduce time and energy during thermal binder removal in the ceramic process, plasma surface treatment was applied before the lamination process.The adhesion strength in the lamination films was enhanced by oxidative plasma treatment of the porous green ceramic film with polymeric binding materials.The oxygen plasma characteristics were investigated through experimental parameters and weight loss analysis.The experimental results revealed the need for parameter analysis,including gas material,process time,flow rate,and discharge power,and supported a mechanism consisting of competing ablation and deposition processes.The weight loss analysis was conducted for cyclic plasma treatment rather than continuous plasma treatment for the purpose of improving the film’s permeability by suppressing deposition of the ablated species.The cyclic plasma treatment improved the permeability compared to the continuous plasma treatment.
文摘A radio frequency argon plasma reactor with a stirrer was employed for the surface treatment of polypropylene （PP） powders. The changes in the superficial contact angle and the superficial composition of the un-treated and treated PP powders were analyzed by means of water contact angle （WCA） measurement, X-ray photoelectron spectroscopy （XPS） and attenuated total reflection Fourier transform infrared spectroscopy （ATR-FTIR）. The water contact angle changed from the original value of 130.2° before plasma treatment to the value of 73.6° after treatment for 5 minutes. With the increase in plasma treating time, there were a decrease in the water contact angle and an increase in the content of oxygen containing polar functional groups （i.e., C-O, C=O and O-C=O）. Both XPS and ATR-FTIR results indicated that the plasma treatment led to the formation of oxygen containing polar functional groups due to oxidation on the surface of the PP powders, and the trend of variation of the water contact angle with plasma treating time was related to the concentration of oxygen atom on the treated PP powders surface. Furthermore, the aging of the plasma-treated PP powders was investigated.
基金supported by the National Key Basic Research Project of China(Grant No.2015CB351901)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA09020201)+2 种基金the Youth Innovation Promotion Association of Chinese Academy of Sciences(Grant No.2013206)the National Natural Science Foundation of China(Grant No.21402233)the Natural Science Foundation of Jiangsu Province,China(Grant Nos.BK2012631and BK20140387)
文摘Polyethylenimine(PEI) interlayer rinsing with different solvents for inverted organic light emitting diodes(OLEDs)is systematically studied in this paper. In comparison with the pristine one, the maximum current efficiency(CE) and power efficiency(PE) are enhanced by 21% and 22% for the device rinsing by ethylene glycol monomethyl ether(EEA).Little effect is found on the work function of the PEI interlayer rinsed by deionized water(DI), ethanol(EtOH), and EEA.On the other hand, the surface morphologies of PEI through different solvent treatments are quite different. Our results indicates that the surface morphology is the key to improving the device performance for IOLED as the work function of PEI keeps stable.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 60776047, 60836003, 60476021 and 60576003)
文摘To form low-resistance Ohmic contact to p-type GaN, InGaN/GaN multiple quantum well light emitting diode wafers are treated with boiled aqua regia prior to Ni/Au （5 nm/5 nm） film deposition. The surface morphology of wafers and the current voltage characteristics of fabricated light emitting diode devices are investigated. It is shown that surface treatment with boiled aqua regia could effectively remove oxide from the surface of the p-GaN layer, and reveal defect-pits whose density is almost the same as the screw dislocation density estimated by x-ray rocking curve measurement. It suggests that the metal atoms of the Ni/Au transparent electrode of light emitting diode devices may diffuse into the p-GaN layer along threading dislocation lines and form additional leakage current channels. Therefore, the surface treatment time with boiled aqua regia should not be too long so as to avoid the increase of threading dislocation-induced leakage current and the degradation of electrical properties of light emitting diodes.
文摘In this study,a high-density polyethylene（HDPE,5-mm-thick,0.95 g/cm3） surface was treated using an RF capacitive atmospheric pressure cold Ar plasma jet.By using this Ar plasma jet,a hydrophilic HDPE surface was formed during the plasma treatment.In particular, the effects of an additive gas（N;or O2） on the HDPE surface treatment were investigated in detail.It was shown that the addition of N2 or O2 gas had an important influence on the HDPE surface treatment.Compared to pure Ar plasma treatment,a lower value of water contact angle （WCA） was obtained when a trace of N2 or O2 gas was added.It was also found that besides the quantities of active species in the plasma jet,the treatment temperature played an important role in the HDPE surface treatment.This is because surface molecular motion is not negligible when the treatment temperature is close to the melting point of the polymer.
基金Supported by the Basic Science Center Project of National Natural Science Foundation of China(72088101)Scientific Research and Technology Development Project of CNPC(2021ZG12)National Key R&D Plan/Key Project of International Scientific and Technological Innovation Cooperation Between Governments(2018YFE0196000).
文摘Based on the structure,working principle,and working conditions of conductance water cut sensor,it is revealed that the early failure of the metal electrode of the sensor is due to the comprehensive influence of well fluid erosion,electrochemical corrosion,and oil pollution during its long-term service in the downhole.A technology for electrode surface treatment is proposed using boron-doped diamond(BDD)films to improve the service performance of the modified electrode.The hot wire chemical vapor deposition method was adopted to fabricate BDD film,the boron doping concentration and deposition time were optimized,and fluorination treatment was applied to improve the wear resistance,electrochemical corrosion resistance,and oleophobic property of the BDD film comprehensively.The results showed that BDD film with boron doping concentration of 6×10^(-3) exhibited high wear resistance and good electrochemical corrosion resistance,and endowed the modified electrode with superior erosion resistance and corrosion resistance.The friction coefficient and wear rate of BDD modified electrode were 92%and 78%lower than those of Invar alloy,also,the low-frequency impedance modulus value of the modified electrode was higher than 1×10^(4) Ω·cm^(2).The BDD film prepared with a deposition time of 8 h had a favorable micro-nano structure owing to small grain size and uniform distribution.Such morphology was conducive to enhancing the oleophobic performance of the modified electrode,and its contact angle in the simulated well fluid was high to 102°.The engineering applicability of BDD film modified electrode under simulated working conditions indicated that,the modified electrode had excellent comprehensive performances of erosion resistance,electrochemical corrosion resistance and oil adhesion resistance,and can realize the long-term stable operation of the conductance water cut sensor under harsh downhole conditions.
文摘The polymer treatment with a low-temperature plasma jet generated on the atmospheric pressure surface discharge （SD） plasma is performed. The change of the surface property over time, in comparison with low pressure oxygen （O2） plasma treatment, is examined. As one compares the treatment by atmospheric pressure plasma to that by the low pressure O2 plasma of PS （polystyrene） the treatment effects were almost in complete agreement. However, when the atmospheric pressure plasma was used for PP（polypropylene）, it produced remarkable hydrophilic effects.
基金supported by the Department of Scientific Research,Eskisehir Osmangazi University,Turkey(No.201441045)
文摘This study aimed to evaluate the surface roughness and wetting properties of various dental prosthetic materials after different durations of non-thermal atmospheric plasma（NTAP）treatment.One hundred and sixty discs of titanium（Ti）（n：40）,cobalt chromium（Co-Cr）（n：40）,yttrium stabilized tetragonal zirconia polycrystals（Y-TZP）（n：40）and polymethylmethacrylate（PMMA）（n：40）materials were machined and smoothed with silicon carbide papers.The surface roughness was evaluated in a control group and in groups with different plasma exposure times [1-3-5 s].The average surface roughness（Ra）and contact angle（CA）measurements were recorded via an atomic force microscope（AFM）and tensiometer,respectively.Surface changes were examined with a scanning electron microscope（SEM）.Data were analyzed with two-way analysis of variance（ANOVA）and the Tukey HSD test α=0.05）.According to the results,the NTAP surface treatment significantly affected the roughness and wettability properties（P 〈 0.05）.SEM images reveal that more grooves were present in the NTAP groups.With an increase in the NTAP application time,an apparent increment was observed for Ra,except in the PMMA group,and a remarkable reduction in CA was observed in all groups.It is concluded that the NTAP technology could enhance the roughening and wetting performance of various dental materials.
基金support provided by Shenzhen-Hong Kong Science and Technology Innovation Cooperation Zone Shenzhen Park Project:HZQB-KCZYB-2020030the Hong Kong General Research Fund(GRF)Scheme(Ref:CityU 11216219)+2 种基金the Research Grants Council of Hong Kong(Project No:AoE/M-402/20)Shenzhen Science and Technology Program:JCYJ20220818101204010the Hong Kong Innovation and Technology Commission via the Hong Kong Branch of National Precious Metals Material Engineering Research Center.
文摘Surface modifications can introduce natural gradients or structural hierarchy into human-made microlattices,making them simultaneously strong and tough.Herein,we describe our investigations of the mechanical properties and the underlying mechanisms of additively manufactured nickel–chromium superalloy(IN625)microlattices after surface mechanical attrition treatment(SMAT).Our results demonstrated that SMAT increased the yielding strength of these microlattices by more than 64.71%and also triggered a transition in their mechanical behaviour.Two primary failure modes were distinguished:weak global deformation,and layer-by-layer collapse,with the latter enhanced by SMAT.The significantly improved mechanical performance was attributable to the ultrafine and hard graded-nanograin layer induced by SMAT,which effectively leveraged the material and structural effects.These results were further validated by finite element analysis.This work provides insight into collapse behaviour and should facilitate the design of ultralight yet buckling-resistant cellular materials.
文摘In this study, commercial biaxially oriented polypropylene （BOPP）, polyvinyl chlo- ride （PVC） and poly （methyl methacrylate） （PMMA） films were treated with nitrogen plasma over different exposure times in a Pyrex tube surrounded by a DC variable magnetic field. The chemi- cal changes that appeared on the surface of the samples were investigated using Fourier transform infrared （FT4R） spectroscopy and attenuated total reflectance Fourier transform infrared （ATR- FTIR） spectroscopy after treatment for 2 min, 4 min and 6 rain in a nitrogen plasma chamber. Effects of the plasma treatment on the surface topographies and contact angles of the untreated and plasma treated films were also analyzed by atomic force microscopy （AFM） and a contact angle measuring system. The results show that the plasma treated films become more hydrophilic with an enhanced wettability due to the formation of some new polar groups on the surface of the treated films. Moreover, at higher exposure times, the total surface energy in all treated films increased while a reduction in contact angle occurred. The behavior of surface roughness in each sample was completely different at higher exposure times.
基金Project supported by the National Natural Science Foundation of China （Grant No 60376019）.
文摘Trichloroethylene （TCE） pretreatment of Si surface prior to HfO2 deposition is employed to fabricate HfO2 gatedielectric MOS capacitors. Influence of this processing procedure on interlayer growth, HfO2/Si interface properties, gate-oxide leakage and device reliability is investigated. Among the surface pretreatments in NH3, NO, N2O and TCE ambients, the TCE pretreatment gives the least interlayer growths the lowest interface-state density, the smallest gate leakage and the highest reliability. All these improvements should be ascribed to the passivation effects of Cl2 and HC1 on the structural defects in the interlayer and at the interface, and also their gettering effects on the ion contamination in the gate dielectric.
基金supported by the Czech Science Foundation(Project No.104/08/02290)
文摘This paper presents the results of aluminum surface treatment by diffuse coplanar surface barrier discharge. The goals are to study the effectiveness of the plasma treatment and the dependence of its efficiency on operation parameters, such as sample-to-electrode distance, treatment time or gas atmosphere. Three types of aluminum materials （bricks, sheets and thin films） were tested to ensure the reliability of the treatment. The changes in the surface properties were characterized by the surface free energy, atomic force microscopy, attenuated total reflectance Fourier transform infrared spectroscopy （ATR FTIR） and X-ray photoelectron spec- troscopy （XPS）. The influence of aging effect on the treatment was also measured and discussed.
文摘Non-thermal plasmas under atmospheric pressure are of great interest in industrial applications, especially in material surface treatment. In this paper, the treatment of a glass surface for improving hydrophobicity using the non-thermal plasma generated by dielectric barrier discharge （DBD） at atmospheric pressure in ambient air is conducted, and the surface properties of the glass before and after the DBD treatment are studied by using contact angle measurement, surface resistance measurement and wet flashover voltage tests. The effects of the applied voltage and time duration of DBD on the surface modification are studied, and the optimal conditions for the treatment are obtained. It is found that a layer of hydrophobic coating is formed on the glass surface after spraying a thin layer of silicone oil and undergoing the DBD treatment, and the improvement of hydrophobicity depends on DBD voltage and treating time. It seems that there exists an optimum treating time for a certain applied voltage of DBD during the surface treatment, The test results of thermal aging and chemical aging show that the hydrophobic layer has quite stable characteristics. The interaction mechanism between the DBD plasma and the glass surface is discussed. It is concluded that CHa and large molecule radicals can react with the radicals in the glass surface to replace OH, and the hydrophobicity of the glass surface is improved accordingly.
基金The National Key Project of China duringthe 10th Five-Year Plan Period (NoMKPT-01-004(ZD))
文摘A new surface strengthening technology, luster polish strengthening treatment, was proposed to treat the raceway surface of aeroengine bearings （9Cr18Mo） with the centrifugal strengthening machine exclusively designed for luster polish strengthening treatment. The experimental results showed that luster polish strengthening treatment produced a compressive residual stress layer with a depth of over 80 μm below the surface of the bearing raceway, and thus effectively removed the metamorphic layer in the raceway surface. After luster polish strengthening treatment, the average surface hardness of the aeroengine bearing raceway was increased from 61.02 HRC to 63.01 HRC, the surface roughness was reduced from 0.06 μm to 0.03 μm, and the contact fatigue life of the aeroengine bearings was improved by about 90%, with the dispersion of fatigue life being reduced remarkably. Theoretical calculation result agrees with that obtained by experiment.
基金Beijing Natural Science Foundation of China(No.2063026)
文摘Natural cellulose was treated by an atmospheidc DBD plasma. The solubility of cellulose in a diluted alkaline solution after the plasma treatment was investigated. The properties were characterized by X-ray photoelectron spectroscopy （XPS）, Fourier-transform infrared spectroscopy （FTIR） and scanning electron microscopy （SEM）. The results indicated that the surface of cellulose treated by the argon DBD plasma was significantly etched, and the relevant force of hydrogen bonding was decreased. This might be the essential reason for the solubility improvement of natural cellulose in the diluted alkaline solution. Through a comparison of two discharge modes, the atmospheric DBD plasma gun and the parallel plate capacitively coupled DBD plasma, it was found that the atmospheric DBD plasma gun was more effective in fragmentizing the cellulose due to its production of a high energy plasma based on its special structure.
基金supported by the University of Malaya Postgraduate Research(PPP)(No.PG062-2016A)RU Grant-Faculty Program(No.GPF042B-2018).
文摘The characteristics of a low power 50 Hz argon plasma for surface treatment of polytetrafluoroethylene(PTFE)film is presented in this article.The current–voltage behavior of the discharge and time-varying intensity of the discharge showed that a DC glow discharge was generated in reversed polarity at every half-cycle.At discharge power between 0.5 and 1 W,the measured electron temperature and density were 2–3 eV and∼10^(8) cm^(−3),respectively.The optical emission spectrum of the argon plasma showed presence of some‘impurity species’such as OH,N_(2) and H,which presumably originated from the residual air in the discharge chamber.On exposure of PTFE films to the argon glow plasma at pressure 120 Pa and discharge power 0.5 to 1 W,the water contact angle reduced by 4%to 20%from the original 114°at pristine condition,which confirms improvement of its surface wettability.The increase in wettability was attributed to incorporation of oxygen-containing functional groups on the treated surface and concomitant reduction in fluorine as revealed by the XPS analysis and increase in surface roughness analyzed from the atomic force micrographs.Ageing upon storage in ambient air showed retention of the induced increase in surface wettability.
