Laser etching and laser chemical vapor deposition(LCVD)techniques were proposed for the rapid preparation of high-purity,strongly bonded SiC porous micro-nano-coatings on quartz substrates.The laser serves as an exter...Laser etching and laser chemical vapor deposition(LCVD)techniques were proposed for the rapid preparation of high-purity,strongly bonded SiC porous micro-nano-coatings on quartz substrates.The laser serves as an external driving force for the vertical growth of SiC whiskers,facilitating the formation of a porous nanostructure that resembles coral models found in the macroscopic biological world.The porous nanostructures are beneficial for reducing thermal expansion mismatch and relieving residual stress.It is capable of eliminating the cracks on the surface of SiC coatings as well as enhancing the bonding of SiC coatings with quartz substrates to avoid coating detachment.展开更多
Food packaging is becoming popular as the consumption of ready-to-eat food products rises.Easyto-use,non-biodegradable plastic packaging is commonly used in food packaging,contributing to the deteriorating environment...Food packaging is becoming popular as the consumption of ready-to-eat food products rises.Easyto-use,non-biodegradable plastic packaging is commonly used in food packaging,contributing to the deteriorating environmental situation.This issue increases the concern for the environment and encourages the usage of alternative materials.Cellulose nanofibrils(CNF)are abundant and biodegradable,which makes them ideal candidates to replace plastic coatings.The ability to form H-bonds between the hydroxyl groups makes coated paper with CNF have good strength,but poor barrier properties.The barrier properties can be improved by grafting DMAEMA or HEMA onto CNF(CNF-g-PDMAEMA and CNF-g-PHEMA,respectively).Thus,the objective of this study was to modify CNF chemically to enhance the barrier properties of the food packaging paper.It was found that paper coated with CNFg-PDMAEMA and CNF-g-PHEMA exhibited improvements in mechanical and barrier properties while maintaining the desired viscosity for the coating process.The water contact angle increased for paper coated with CNF-g-PHEMA and CNF-g-PDMAEMA,reaching a maximum of 97.51°and 92.58°,respectively with the decreasing Cobb_(60) values by 49% and 11%.The oil absorption was also reduced for both coated papers compared to the blank paper.Mechanical properties improved,as indicated by a 3% increase in tensile strength for paper coated with CNF-g-PHEMA and a 5% for paper coated with CNF-g-PDMAEMA.The results indicated significant potential for the application of modified CNF in coatings for food packaging paper.Noteworthy,the grafting process should be improved to enhance the mechanical and barrier properties of the coated paper.展开更多
A Ni layer with a thickness of about 100 nm was sputtered on Cu substrates,followed by an ultrasonic seeding with nanodiamond suspension.High-quality diamond film with its crystalline grains close to thermal equilibri...A Ni layer with a thickness of about 100 nm was sputtered on Cu substrates,followed by an ultrasonic seeding with nanodiamond suspension.High-quality diamond film with its crystalline grains close to thermal equilibrium shape was deposited on Cu substrates by hot-filament chemical vapor deposition（HF-CVD）,and the sp2 carbon content was less than 5.56%.The nucleation and growth of diamond film were investigated by micro-Raman spectroscopy,scanning electron microscopy,and X-ray diffraction.The results show that the nucleation density of diamond on the Ni-modified Cu substrates is 10 times higher than that on blank Cu substrates.The enhancement mechanism of the nucleation kinetics by Ni modification layer results from two effects：namely,the nanometer rough Ni-modified surface shows an improved absorption of nanodiamond particles that act as starting points for the diamond nucleation during HF-CVD process;the strong catalytic effect of the Ni-modified surface causes the formation of graphite layer that acts as an intermediate to facilitate diamond nucleation quickly.展开更多
The effect of heat treatment on the transformation temperature of Ti?52.2%Ni (mole fraction) alloy was studied using differential scanning calorimetry (DSC). The transformation temperatures of the alloy can be adjuste...The effect of heat treatment on the transformation temperature of Ti?52.2%Ni (mole fraction) alloy was studied using differential scanning calorimetry (DSC). The transformation temperatures of the alloy can be adjusted effectively by heat treatment. Dense and stable SiO2 coatings were deposited on the surface of the pre-oxidized TiNi alloy by sol?gel method. The bonding strength of films and matrix was (65.9±1.5) N. The electrochemical corrosion test shows that the TiNi alloy with SiO2 coating has excellent corrosion resistance in the Hank’s simulated body fluid. The release behaviors of Ni ion of the alloy with and without SiO2 coating implanted in the acoustic vesicle of guinea pig were studied by EDS testing, which was inhibited effectively by the dense and stable SiO2 coating on the alloy.展开更多
The fine rnicrostrueture of the Y-modified ion plated Ti(Y)N coating/substrate steel A3 system has been examined by means of TEM and microdiffraction technique.It was revealed that the interface consists of 3 sublayer...The fine rnicrostrueture of the Y-modified ion plated Ti(Y)N coating/substrate steel A3 system has been examined by means of TEM and microdiffraction technique.It was revealed that the interface consists of 3 sublayers,i.e.α-Fe+Y_6Fe_(23),Ti+Y+FeTi and Ti_2N+YN +Ti_xN_y.The thicknesses of them are about 200,50 and 120 nm respectively.The phases in the transition area seem to have certain orientation relations.The mechanism of interface formation has also been discussed.展开更多
Platinum group metals have high melting points,strong corrosion resistance,stable chemical properties,and low oxygen permeability in high-temperature oxygen-containing environments.As thermal protective coating materi...Platinum group metals have high melting points,strong corrosion resistance,stable chemical properties,and low oxygen permeability in high-temperature oxygen-containing environments.As thermal protective coating materials,they have gained essential applications in the aerospace field and have excellent prospects for application in frontier military fields,such as protecting hot-end components of hypersonic aircraft.This research reviewed the latest research progress of platinum group metal coatings with hightemperature oxidation resistance,including coating preparation techniques,oxidation failure,and alloying modification.The leading preparation techniques of current platinum group metal coatings were discussed,as well as the advantages and disadvantages of various existing preparation techniques.Besides,the intrinsic properties,failure forms,and failure mechanisms of coatings of single platinum group metal in high-temperature oxygen-containing environments were analyzed.On this basis,the necessity,main methods,and main achievements of alloying modification of platinum group metals were summarized.Finally,the future development of platinum group coatings with high-temperature oxidation resistance was discussed and prospected.展开更多
The incorporation of KH560-modified steel slag(MSS)as a filler in alkyd coatings significantly impacts their corrosion resistance and mechanical properties.The modification process was characterized using the Fourier ...The incorporation of KH560-modified steel slag(MSS)as a filler in alkyd coatings significantly impacts their corrosion resistance and mechanical properties.The modification process was characterized using the Fourier transform infrared spectrometer,scanning electron microscope,and X-ray photoelectron spectroscope to understand the chemical and morphological changes induced by KH560 treatment.Three types of coatings were prepared:pure alkyd coating(AC),steel slag/alkyd coating(SS/AC),and KH560-modified steel slag/alkyd coating(MSS/AC).Their corrosion resistance was evaluated by electrochemical impedance spectroscopy and salt spray tests,while mechanical properties such as hardness,adhesion,and flexibility were also assessed.Results show that MSS significantly enhances the hardness,flexibility,and adhesion of the coatings,forming a composite structure(MSS-KH560-alkyd)that significantly improves the performance of MSS/AC.Notably,MSS/AC demonstrated superior hydrophobicity with a water absorption rate of 0.624%and a contact angle of 100.7°.Electrochemical tests revealed an impedance modulus of 3.9×10^(7)Ωcm^(2),a corrosion current of 3.39×10^(−4)mA,and a corrosion potential of−35 mV for MSS/AC.After a 10-d immersion in a 3.5 wt.%NaCl solution,MSS/AC maintained its protective properties.These findings underscore the potential of MSS as a sustainable and effective filler for alkyd coatings in corrosion protection applications.展开更多
To reveal the influence of substrate/coating interdiffusion on the cyclic oxidation property of a metallic coating, cyclic oxida- tion behavior of an EB-PVD CoCrAIY coating on directionally solidified Ni-based superal...To reveal the influence of substrate/coating interdiffusion on the cyclic oxidation property of a metallic coating, cyclic oxida- tion behavior of an EB-PVD CoCrAIY coating on directionally solidified Ni-based superalloy DZ125 at 1 050℃ is investigated. The 40 μm thick CoCrA1Y coating has a cyclic oxidation life of around 160 h, and the oxidation constant is 1.915× 10^-7 mg4.cm^-8.s-1. However, severe spallation of the oxides containing Co, Cr, Ni, Ta and Ti occurs with longer cyclic oxidation. The degradation in oxidation resistance for the coating is related to the depletion of A1 due to the oxide spallation and interdiffu- sion. Severe interdiffusion between the coating and underlying substrate occurs at 1 050 ℃. The composition of the substrate has an important effect on the thermal cycling lifetime of the coating. The influencing mechanism is discussed.展开更多
Developing advanced technologies to address the bacterial associated infections is an urgent requirement for metallic implants and devices.Here,we report a novel phosphonate/quaternary amine block polymer as the high-...Developing advanced technologies to address the bacterial associated infections is an urgent requirement for metallic implants and devices.Here,we report a novel phosphonate/quaternary amine block polymer as the high-efficiency antibacterial coating for metallic substrates.Three pDEMMP-b-pTMAEMA block polymers that bearing identical phosphonate segments(repeat units of 15)but varied cationic segments(repeat units of 8,45,and 70)were precisely prepared.Stable cationic polymer coatings were constructed on TC4 substrates based on the strong covalent binding between phosphonate group and metallic substrate.Robust relationship between the segment chain length of the polymer coating and the antibacterial property endowed to the substrates have been established based on quantitative and qualitative evaluations.Results showed that the antibacterial rate of the modified TC4 surface were 95.8%of S.aureus and 92.9%of E.coli cells attached.Interestingly,unlike the cationic free polymer or cationic hydrogels,the surface anchored cationic polymers do compromise the viability of the attached C2C12 cells but without significant cytotoxicity.In addition,the phosphonate/quate rnary amine block polymers can be easily constructed on titanium,stainless steel,and Ni/Cr alloy with significantly improved antibacterial property,indicating the generality of the block polymer for surface antibacterial modification of bio-metals.展开更多
The Cr-plated coating inside a gun barrel can effectively improve the barrel’s erosion resistance and thus increase the service life.However,due to the cyclic thermal load caused by high-temperature gunpowder,micro-e...The Cr-plated coating inside a gun barrel can effectively improve the barrel’s erosion resistance and thus increase the service life.However,due to the cyclic thermal load caused by high-temperature gunpowder,micro-element damage tends to occur within the Cr coating/steel substrate interface,leading to a gradual deterioration in macro-mechanical properties for the material in the related region.In order to mimic this cyclic thermal load and,thereby,study the thermal erosion behavior of the Cr coating on the barrel’s inner wall,a laser emitter is utilized in the current study.With the help of in-situ tensile test and finite element simulation results,a shear stress distribution law of the Cr coating/steel substrate and a change law of the interface ultimate shear strength are identified.Studies have shown that the Cr coating/steel substrate interface’s ultimate shear strength has a significant weakening effect due to increasing temperature.In this study,the interfacial ultimate shear strength decreases from 2.57 GPa(no erosion)to 1.02 GPa(laser power is 160 W).The data from this experiment is employed to establish a Cr coating/steel substrate interface shear damage model.And this model is used to predict the flaking process of Cr coating by finite element method.The simulation results show that the increase of coating crack spacing and coating thickness will increase the service life of gun barrel.展开更多
Air plasma sprayed thermal barrier coatings(APS-TBCs)saw their wide application in high-temperaturerelated cutting-edge fields.The lamellar structure of APS-TBCs provides a significant advantage on thermal insulation....Air plasma sprayed thermal barrier coatings(APS-TBCs)saw their wide application in high-temperaturerelated cutting-edge fields.The lamellar structure of APS-TBCs provides a significant advantage on thermal insulation.However,short life span is a major headache for APS-TBCs.This is highly related to the property changes and passive behaviors of the coatings during thermal service.Herein,a finite element model was developed to investigate the dynamic stiffening and substrate constraint on total spallation process.Results show that the stiffening accelerates the crack propagation of APS-TBCs.The driving force for crack propagation,which is characterized by strain energy release rate(SERR),is significantly enlarged.Consequently,the crack starts to propagate when the SERR exceeds the fracture toughness.In addition,the changing trends of SERR and crack propagation features are highly associated with temperatures.A higher temperature corresponds to more significant effect of stiffening on substrate constraint.In brief,temperature-dependent stiffening significantly aggravates the substrate constraint effect on APS-TBCs,which is one of the major causes for the spallation.Given that,lowering stiffening degree is essential to maintain high strain tolerance,and to further extend the life span of APS-TBCs.This understanding contributes to the development of advanced TBCs in future applications.展开更多
Hypereutectic Al-Si-Cu coatings were prepared by supersonic atmospheric plasma spraying to enhance the surface performance of lightweight alloys.To find out optimum process conditions and achieve desirable coatings,th...Hypereutectic Al-Si-Cu coatings were prepared by supersonic atmospheric plasma spraying to enhance the surface performance of lightweight alloys.To find out optimum process conditions and achieve desirable coatings,this work focuses on the influence of three important parameters(in-flight particle temperature,impact velocity,and substrate temperature)on the collected splats morphology coatings microstructure and microhardness.Results show that appropriate combinations of temperature and velocity of in-flight particles cannot only completely melt hypereutectic Al-Si-Cu particles especially the primary Si phase,but also provide the particles with sufficient kinetic energy.Thus,the optimized coating consists of 98.6%of fully-melted region with nanosized coupled eutectic and 0.9%of porosity.Increasing the substrate deposition temperature promotes the transition from inhomogeneous banded microstructure to homogeneous equiaxed microstructure with a lower porosity level.The observations are further interpreted by a newly developed phase-change heat transfer model on quantitatively revealing the solidification and remelting behaviors of several splats deposited on substrate Besides,phase evolutions including the formation of supersaturatedα-Al matrix solid solution,growth of Si and Al_(2)Cu phases at different process conditions are elaborated.An ideal microstructure(low fractions of unmelted/partially-melted regions and defects)together with solid solution,grain refinement and second phase strengthening effects contributes to the enhanced microhardness of coating.This integrated study not only provides a framework for optimizing Al-Si based coatings via thermal spraying but also gives valuable insights into the formation mechanisms of this class of coating materials.展开更多
The thermal barrier coatings with NiCrAlY alloy bonding layer, NiCrAlY Y 2O 3 stabilized ZrO 2 transition layer and Y 2O 3 stabilized ZrO 2 ceramic layer are prepared on nickel alloy substrates using the plasma spray ...The thermal barrier coatings with NiCrAlY alloy bonding layer, NiCrAlY Y 2O 3 stabilized ZrO 2 transition layer and Y 2O 3 stabilized ZrO 2 ceramic layer are prepared on nickel alloy substrates using the plasma spray technique. The relationship among the composition, structure and property of the coatings are investiga ted by means of optical microscope, scanning electronic microscope and the experiments of thermal shock resistance cycling and high temperature oxidation resistance. The results show that the structure design of introdu cing a transition layer between Ni alloy substrate and ZrO 2 ceramic coating guarantees the high quality and properties of the coatings; ZrO 2 coatings doped with a little SiO 2 possesses better thermal shock resistance and more excellent hot corrosion resistance as compared with ZrO 2 coating materials without SiO 2 ;the improvement in performance of ZrO 2 coating doped with SiO 2 is due to forming more dense coating structure by self closing effects of the flaws and pores in the ZrO 2 coatings.展开更多
NiMnO3 perovskite catalysts supported on cordierite modified by CexZr（1-x）O2 coatings were prepared using impregnation and sol-gel methods for catalytic combustion of single/double component VOCs at different concen...NiMnO3 perovskite catalysts supported on cordierite modified by CexZr（1-x）O2 coatings were prepared using impregnation and sol-gel methods for catalytic combustion of single/double component VOCs at different concentrations and GHSV of 15,000 h^（-1）, which were characterized by BET, XRD, SEM, FT-IR, H2-TPR and O2-TPD. After coating modification, the specific surface area of catalysts is improved obviously.Among the catalysts, the Ce（0.75）Zr（0.25）O2 coating modified NiMnO3 catalyst exhibits the best catalytic activity for VOCs combustion with 95.6% conversion at 275 ℃ and has stable activity when catalyst is embalmed at 800 ℃. In addition, the catalyst also presents the excellent water-resistant and conversion stability over time-on-stream condition. The reason is that Ce（0.75）Zr（0.25）O2 coating can promote more lattice distortion and defects and smaller crystal size, which improve oxygen transfer capability and dispersion of active component.展开更多
Ammonium nitrate(AN)is promising oxidizer in green propellants.In this work,the physical coating method was improved to modify the surface of ammonium nitrate particles with different surfactant materials to reduce hy...Ammonium nitrate(AN)is promising oxidizer in green propellants.In this work,the physical coating method was improved to modify the surface of ammonium nitrate particles with different surfactant materials to reduce hygroscopicity.Cetylalcohoi,stearic acid,stearyl alcohol,palmic acid,lauric acid,stearsmide,tetradecylamine,dodecylamine,and tetradecanol were used as coating surfactant agents.The hygroscopicity was tested for ammonium nitrate with and without coating.Fourier transform infrared(FTIR)and scanning electron microscopy(SEM)were used to characterize the surface of coated and uncoated ammonium nitrate.The mass ratio of coating layer and decline of absorption rate of ammonium nitrate coated by cetylalcohol were 1.00%,and 28.40%,respectively.The results indicate that coating with cetylalcohol surfactant have advantages over the other surfactants in term of low mass ratio of coating layer,and high decline of moisture absorption rate.Thus,cetylalcohol would be a promising coating surfactant material for ammonium nitrate.The idea and approach presented in this study have potential to made hydrophobic layer on the surface of particles to reduce hygroscopicity of AN,and also help the researcher to improving anti-hygroscopicity of ammonium salts.展开更多
The coating of ZnS∶Mn by Sb-doped SnO2 using an co-precipitation process was reported. ZnS∶Mn phosphor particles were prepared by solid reaction with ZnS and MnCl2·4H2O. Surface modification of the ZnS∶Mn powd...The coating of ZnS∶Mn by Sb-doped SnO2 using an co-precipitation process was reported. ZnS∶Mn phosphor particles were prepared by solid reaction with ZnS and MnCl2·4H2O. Surface modification of the ZnS∶Mn powders was carried out by coating transparent conductive films of Sb-doped tin oxides which were formed by co-precipitation and heat treatment process. Tin tetrachloride and antimony trichloride were used as the precursor materials for the co-precipitation. The influences of coating molar ratio, Sb concentration in the coatings, annealing temperature and time on the resistivity of coated ZnS∶Mn phosphors were investigated. The optimum co-precipitation processing parameters and annealing conditions were determined. The phosphors were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), photoluminescence(PL) observation and conductance measurements. An improvement in phosphors conductivity was observed while the respective photoluminescence intensity is analogous to the as-prepared ZnS∶Mn phosphors.展开更多
A kind of modifier was synthesized to modify the surface of nanometer calcium carbonate （abbreviated as nano-CaCO3）, which is used in architectural coatings. The modification technology of the nano-CaCO3 was studied...A kind of modifier was synthesized to modify the surface of nanometer calcium carbonate （abbreviated as nano-CaCO3）, which is used in architectural coatings. The modification technology of the nano-CaCO3 was studied through orthogonal experimental methods. The factors studied were rotation speed, modifier dosage, emulsification temperature, emulsification time and heat aging time after emulsification. Optimized conditions for modification of the surface were： rotation speed 16000 r/min; modifier dosage 3%; emulsification temperature 75 ℃; emulsification time 60 min and aging time 40 min. The modified nano-CaCO3 was also studied by size-distribution measurements, transmission electron microscopy, infrared spectroscopy and thermal analysis. The results show that the size distribution of the modified nano-CaCO3 is uniform and that there are chemi-sorption and physi-sorption between the nano-CaCO3 and the modifier. Compared to traditional architectural coatings without nano-CaCO3, the nanometer composite coatings are obviously improved in respect to dirt resistance, scrub resistance, thixotropy, water resistance, alkalinity resistance and aging resistance.展开更多
Silk fibroin(SF)as a natural biopolymer has become a popular material for biomedical applications due to its minimal immunogenicity,tunable biodegradability,and high biocompatibility.Nowadays,various techniques have b...Silk fibroin(SF)as a natural biopolymer has become a popular material for biomedical applications due to its minimal immunogenicity,tunable biodegradability,and high biocompatibility.Nowadays,various techniques have been developed for the applications of SF in bioengineering.Most of the literature reviews focus on the SF-based biomaterials and their different forms of applications such as films,hydrogels,and scaffolds.SF is also valuable as a coating on other substrate materials for biomedicine;however,there are few reviews related to SF-coated biomaterials.Thus,in this review,we focused on the surface modification of biomaterials using SF coatings,demonstrated their various preparation methods on substrate materials,and introduced the latest procedures.The diverse applications of SF coatings for biomedicine are discussed,including bone,ligament,skin,mucosa,and nerve regeneration,and dental implant surface modification.SF coating is conducive to inducing cell adhesion and migration,promoting hydroxyapatite(HA)deposition and matrix mineralization,and inhibiting the Notch signaling pathway,making it a promising strategy for bone regeneration.In addition,SF-coated composite scaffolds can be considered prospective candidates for ligament regeneration after injury.SF coating has been proven to enhance the mechanical properties of the substrate material,and render integral stability to the dressing material during the regeneration of skin and mucosa.Moreover,SF coating is a potential strategy to accelerate nerve regeneration due to its dielectric properties,mechanical flexibility,and angiogenesis promotion effect.In addition,SF coating is an effective and popular means for dental implant surface modification to promote osteogenesis around implants made of different materials.Thus,this review can be of great benefit for further improvements in SF-coated biomaterials,and will undoubtedly contribute to clinical transformation in the future.展开更多
To prolong the service lifetime of hot-section components used in marine environment at elevated tem-peratures,it is crucial to explore and develop high-temperature corrosion-resistant coatings.High-velocity oxygen fu...To prolong the service lifetime of hot-section components used in marine environment at elevated tem-peratures,it is crucial to explore and develop high-temperature corrosion-resistant coatings.High-velocity oxygen fuel(HVOF)sprayed NiCoCrAlY,Pt-modified NiCoCrAlY and pre-oxidized Pt-modified NiCoCrAlY coatings were prepared and investigated.This study is concerned with the performance of three coat-ings in a simulated marine environment based on the phase composition of corrosion products and mi-crostructure evolution of coating samples combined with first-principles density functional theory.The results show that the NiCoCrAlY coating was subject to accelerated corrosion and extensive aluminum depletion,leading to premature coating failure.The high-temperature corrosion resistance of Pt-modified NiCoCrAlY coating was found to be better than that of NiCoCrAlY coating.In contrast,the pre-oxidized Pt-modified NiCoCrAlY coating offered long-lasting protection and exhibited the best corrosion resistance,which is attributed to the positive synergistic effect between Pt modification and pre-oxidation.展开更多
基金Funded by the International Science&Technology Cooperation Program of Hubei Province of China(No.2022EHB024)the National Key Research and Development Plan(Nos.2018YFE0103600 and 2021YFB3703100)+1 种基金the National Natural Science Foundation of China(Nos.51872212,51972244,52002075,and 52102066)the 111 Project(No.B13035)。
文摘Laser etching and laser chemical vapor deposition(LCVD)techniques were proposed for the rapid preparation of high-purity,strongly bonded SiC porous micro-nano-coatings on quartz substrates.The laser serves as an external driving force for the vertical growth of SiC whiskers,facilitating the formation of a porous nanostructure that resembles coral models found in the macroscopic biological world.The porous nanostructures are beneficial for reducing thermal expansion mismatch and relieving residual stress.It is capable of eliminating the cracks on the surface of SiC coatings as well as enhancing the bonding of SiC coatings with quartz substrates to avoid coating detachment.
基金supported by Hibah Penelitian Fundamental Reguler Kementerian Pendidikan,Kebudayaan,Riset dan Teknologi under funding year of 2024 with contract number:051/E5/PG.02.00.PL/2024NKB-903/UN2.RST/HKP.05.00/2024.
文摘Food packaging is becoming popular as the consumption of ready-to-eat food products rises.Easyto-use,non-biodegradable plastic packaging is commonly used in food packaging,contributing to the deteriorating environmental situation.This issue increases the concern for the environment and encourages the usage of alternative materials.Cellulose nanofibrils(CNF)are abundant and biodegradable,which makes them ideal candidates to replace plastic coatings.The ability to form H-bonds between the hydroxyl groups makes coated paper with CNF have good strength,but poor barrier properties.The barrier properties can be improved by grafting DMAEMA or HEMA onto CNF(CNF-g-PDMAEMA and CNF-g-PHEMA,respectively).Thus,the objective of this study was to modify CNF chemically to enhance the barrier properties of the food packaging paper.It was found that paper coated with CNFg-PDMAEMA and CNF-g-PHEMA exhibited improvements in mechanical and barrier properties while maintaining the desired viscosity for the coating process.The water contact angle increased for paper coated with CNF-g-PHEMA and CNF-g-PDMAEMA,reaching a maximum of 97.51°and 92.58°,respectively with the decreasing Cobb_(60) values by 49% and 11%.The oil absorption was also reduced for both coated papers compared to the blank paper.Mechanical properties improved,as indicated by a 3% increase in tensile strength for paper coated with CNF-g-PHEMA and a 5% for paper coated with CNF-g-PDMAEMA.The results indicated significant potential for the application of modified CNF in coatings for food packaging paper.Noteworthy,the grafting process should be improved to enhance the mechanical and barrier properties of the coated paper.
基金Project(20110933K) supported by the State Key Laboratory of Powder Metallurgy,ChinaProject(2012QNZT002) supported by the Freedom Explore Program of Central South University,ChinaProject(CSUZC2012024) supported by the Open-End Fund for the Valuable and Precision Instruments of Central South University,China
文摘A Ni layer with a thickness of about 100 nm was sputtered on Cu substrates,followed by an ultrasonic seeding with nanodiamond suspension.High-quality diamond film with its crystalline grains close to thermal equilibrium shape was deposited on Cu substrates by hot-filament chemical vapor deposition（HF-CVD）,and the sp2 carbon content was less than 5.56%.The nucleation and growth of diamond film were investigated by micro-Raman spectroscopy,scanning electron microscopy,and X-ray diffraction.The results show that the nucleation density of diamond on the Ni-modified Cu substrates is 10 times higher than that on blank Cu substrates.The enhancement mechanism of the nucleation kinetics by Ni modification layer results from two effects：namely,the nanometer rough Ni-modified surface shows an improved absorption of nanodiamond particles that act as starting points for the diamond nucleation during HF-CVD process;the strong catalytic effect of the Ni-modified surface causes the formation of graphite layer that acts as an intermediate to facilitate diamond nucleation quickly.
基金Project(81170609)supported by the National Natural Science Foundation of ChinaProject(11JJ6087)supported by the Nature Science Foundation of Hunan Province,ChinaProject supported by the Open Project of State Key Laboratory of Powder Metallurgy,Central South University,China
文摘The effect of heat treatment on the transformation temperature of Ti?52.2%Ni (mole fraction) alloy was studied using differential scanning calorimetry (DSC). The transformation temperatures of the alloy can be adjusted effectively by heat treatment. Dense and stable SiO2 coatings were deposited on the surface of the pre-oxidized TiNi alloy by sol?gel method. The bonding strength of films and matrix was (65.9±1.5) N. The electrochemical corrosion test shows that the TiNi alloy with SiO2 coating has excellent corrosion resistance in the Hank’s simulated body fluid. The release behaviors of Ni ion of the alloy with and without SiO2 coating implanted in the acoustic vesicle of guinea pig were studied by EDS testing, which was inhibited effectively by the dense and stable SiO2 coating on the alloy.
文摘The fine rnicrostrueture of the Y-modified ion plated Ti(Y)N coating/substrate steel A3 system has been examined by means of TEM and microdiffraction technique.It was revealed that the interface consists of 3 sublayers,i.e.α-Fe+Y_6Fe_(23),Ti+Y+FeTi and Ti_2N+YN +Ti_xN_y.The thicknesses of them are about 200,50 and 120 nm respectively.The phases in the transition area seem to have certain orientation relations.The mechanism of interface formation has also been discussed.
文摘Platinum group metals have high melting points,strong corrosion resistance,stable chemical properties,and low oxygen permeability in high-temperature oxygen-containing environments.As thermal protective coating materials,they have gained essential applications in the aerospace field and have excellent prospects for application in frontier military fields,such as protecting hot-end components of hypersonic aircraft.This research reviewed the latest research progress of platinum group metal coatings with hightemperature oxidation resistance,including coating preparation techniques,oxidation failure,and alloying modification.The leading preparation techniques of current platinum group metal coatings were discussed,as well as the advantages and disadvantages of various existing preparation techniques.Besides,the intrinsic properties,failure forms,and failure mechanisms of coatings of single platinum group metal in high-temperature oxygen-containing environments were analyzed.On this basis,the necessity,main methods,and main achievements of alloying modification of platinum group metals were summarized.Finally,the future development of platinum group coatings with high-temperature oxidation resistance was discussed and prospected.
基金financially supported by the National Natural Science Foundation of China(No.U23A20605)the Outstanding Youth Fund of Anhui Province(2208085J19)China Baowu Low Carbon Metallurgy Innovation Foundation(No.BWLCF202202).
文摘The incorporation of KH560-modified steel slag(MSS)as a filler in alkyd coatings significantly impacts their corrosion resistance and mechanical properties.The modification process was characterized using the Fourier transform infrared spectrometer,scanning electron microscope,and X-ray photoelectron spectroscope to understand the chemical and morphological changes induced by KH560 treatment.Three types of coatings were prepared:pure alkyd coating(AC),steel slag/alkyd coating(SS/AC),and KH560-modified steel slag/alkyd coating(MSS/AC).Their corrosion resistance was evaluated by electrochemical impedance spectroscopy and salt spray tests,while mechanical properties such as hardness,adhesion,and flexibility were also assessed.Results show that MSS significantly enhances the hardness,flexibility,and adhesion of the coatings,forming a composite structure(MSS-KH560-alkyd)that significantly improves the performance of MSS/AC.Notably,MSS/AC demonstrated superior hydrophobicity with a water absorption rate of 0.624%and a contact angle of 100.7°.Electrochemical tests revealed an impedance modulus of 3.9×10^(7)Ωcm^(2),a corrosion current of 3.39×10^(−4)mA,and a corrosion potential of−35 mV for MSS/AC.After a 10-d immersion in a 3.5 wt.%NaCl solution,MSS/AC maintained its protective properties.These findings underscore the potential of MSS as a sustainable and effective filler for alkyd coatings in corrosion protection applications.
基金National Natural Science Foundation of China (50731001, 51071013, 51001032)National Basic Research Program of China (2010CB631200)
文摘To reveal the influence of substrate/coating interdiffusion on the cyclic oxidation property of a metallic coating, cyclic oxida- tion behavior of an EB-PVD CoCrAIY coating on directionally solidified Ni-based superalloy DZ125 at 1 050℃ is investigated. The 40 μm thick CoCrA1Y coating has a cyclic oxidation life of around 160 h, and the oxidation constant is 1.915× 10^-7 mg4.cm^-8.s-1. However, severe spallation of the oxides containing Co, Cr, Ni, Ta and Ti occurs with longer cyclic oxidation. The degradation in oxidation resistance for the coating is related to the depletion of A1 due to the oxide spallation and interdiffu- sion. Severe interdiffusion between the coating and underlying substrate occurs at 1 050 ℃. The composition of the substrate has an important effect on the thermal cycling lifetime of the coating. The influencing mechanism is discussed.
基金the grant supports from the National Natural Science Foundation of China(No.21504046)the Six Talent Peaks Project in Jiangsu Province(SWYY-060)+1 种基金the Projects of Nanjing Normal University(No.184080H20192184080H10386)。
文摘Developing advanced technologies to address the bacterial associated infections is an urgent requirement for metallic implants and devices.Here,we report a novel phosphonate/quaternary amine block polymer as the high-efficiency antibacterial coating for metallic substrates.Three pDEMMP-b-pTMAEMA block polymers that bearing identical phosphonate segments(repeat units of 15)but varied cationic segments(repeat units of 8,45,and 70)were precisely prepared.Stable cationic polymer coatings were constructed on TC4 substrates based on the strong covalent binding between phosphonate group and metallic substrate.Robust relationship between the segment chain length of the polymer coating and the antibacterial property endowed to the substrates have been established based on quantitative and qualitative evaluations.Results showed that the antibacterial rate of the modified TC4 surface were 95.8%of S.aureus and 92.9%of E.coli cells attached.Interestingly,unlike the cationic free polymer or cationic hydrogels,the surface anchored cationic polymers do compromise the viability of the attached C2C12 cells but without significant cytotoxicity.In addition,the phosphonate/quate rnary amine block polymers can be easily constructed on titanium,stainless steel,and Ni/Cr alloy with significantly improved antibacterial property,indicating the generality of the block polymer for surface antibacterial modification of bio-metals.
文摘The Cr-plated coating inside a gun barrel can effectively improve the barrel’s erosion resistance and thus increase the service life.However,due to the cyclic thermal load caused by high-temperature gunpowder,micro-element damage tends to occur within the Cr coating/steel substrate interface,leading to a gradual deterioration in macro-mechanical properties for the material in the related region.In order to mimic this cyclic thermal load and,thereby,study the thermal erosion behavior of the Cr coating on the barrel’s inner wall,a laser emitter is utilized in the current study.With the help of in-situ tensile test and finite element simulation results,a shear stress distribution law of the Cr coating/steel substrate and a change law of the interface ultimate shear strength are identified.Studies have shown that the Cr coating/steel substrate interface’s ultimate shear strength has a significant weakening effect due to increasing temperature.In this study,the interfacial ultimate shear strength decreases from 2.57 GPa(no erosion)to 1.02 GPa(laser power is 160 W).The data from this experiment is employed to establish a Cr coating/steel substrate interface shear damage model.And this model is used to predict the flaking process of Cr coating by finite element method.The simulation results show that the increase of coating crack spacing and coating thickness will increase the service life of gun barrel.
基金financially supported by the National Science and Technology Major Project(2017-VII-0012-0107)the China Postdoctoral Science Foundation(Nos.2019T120903 and 2018M631151)+5 种基金the Natural Science Foundation of Shaanxi Province(No.2019JQ-165)the Domain Foundation of Equipment Advance Research of 13th Five-year Plan(No.JZX7Y20190262062001)the Postdoctoral Science Foundation of Shaanxi Province(No.2018BSHYDZZ59)the opening foundation from Science and Technology on Plasma Dynamics Laboratory in Air Force Engineering University of China(No.61422020701)the Young Talent fund of University Association for Science and Technology in Shaanxi,China(No.20190403)The financial support from China Scholarship Council(CSC)to be a postdoctoral researcher in Forschungszentrum Jülich would be greatly appreciated by Dr.G.R.Li(No.201806285079)。
文摘Air plasma sprayed thermal barrier coatings(APS-TBCs)saw their wide application in high-temperaturerelated cutting-edge fields.The lamellar structure of APS-TBCs provides a significant advantage on thermal insulation.However,short life span is a major headache for APS-TBCs.This is highly related to the property changes and passive behaviors of the coatings during thermal service.Herein,a finite element model was developed to investigate the dynamic stiffening and substrate constraint on total spallation process.Results show that the stiffening accelerates the crack propagation of APS-TBCs.The driving force for crack propagation,which is characterized by strain energy release rate(SERR),is significantly enlarged.Consequently,the crack starts to propagate when the SERR exceeds the fracture toughness.In addition,the changing trends of SERR and crack propagation features are highly associated with temperatures.A higher temperature corresponds to more significant effect of stiffening on substrate constraint.In brief,temperature-dependent stiffening significantly aggravates the substrate constraint effect on APS-TBCs,which is one of the major causes for the spallation.Given that,lowering stiffening degree is essential to maintain high strain tolerance,and to further extend the life span of APS-TBCs.This understanding contributes to the development of advanced TBCs in future applications.
基金financially supported by the National Natural Science Foundation of China(Nos.51535011,51675531,52075542 and 52075543)the Pre-Research Program in National 13th FiveYear Plan(No.61409230603)+2 种基金the Joint Fund of Ministry of Education for Pre-research of Equipment(No.6141A02033120)the China Postdoctoral Science Foundation(No.2019M653598)the Natural Science Basic Research Plan in Shaanxi Province of China(No.2020JQ-911)。
文摘Hypereutectic Al-Si-Cu coatings were prepared by supersonic atmospheric plasma spraying to enhance the surface performance of lightweight alloys.To find out optimum process conditions and achieve desirable coatings,this work focuses on the influence of three important parameters(in-flight particle temperature,impact velocity,and substrate temperature)on the collected splats morphology coatings microstructure and microhardness.Results show that appropriate combinations of temperature and velocity of in-flight particles cannot only completely melt hypereutectic Al-Si-Cu particles especially the primary Si phase,but also provide the particles with sufficient kinetic energy.Thus,the optimized coating consists of 98.6%of fully-melted region with nanosized coupled eutectic and 0.9%of porosity.Increasing the substrate deposition temperature promotes the transition from inhomogeneous banded microstructure to homogeneous equiaxed microstructure with a lower porosity level.The observations are further interpreted by a newly developed phase-change heat transfer model on quantitatively revealing the solidification and remelting behaviors of several splats deposited on substrate Besides,phase evolutions including the formation of supersaturatedα-Al matrix solid solution,growth of Si and Al_(2)Cu phases at different process conditions are elaborated.An ideal microstructure(low fractions of unmelted/partially-melted regions and defects)together with solid solution,grain refinement and second phase strengthening effects contributes to the enhanced microhardness of coating.This integrated study not only provides a framework for optimizing Al-Si based coatings via thermal spraying but also gives valuable insights into the formation mechanisms of this class of coating materials.
文摘The thermal barrier coatings with NiCrAlY alloy bonding layer, NiCrAlY Y 2O 3 stabilized ZrO 2 transition layer and Y 2O 3 stabilized ZrO 2 ceramic layer are prepared on nickel alloy substrates using the plasma spray technique. The relationship among the composition, structure and property of the coatings are investiga ted by means of optical microscope, scanning electronic microscope and the experiments of thermal shock resistance cycling and high temperature oxidation resistance. The results show that the structure design of introdu cing a transition layer between Ni alloy substrate and ZrO 2 ceramic coating guarantees the high quality and properties of the coatings; ZrO 2 coatings doped with a little SiO 2 possesses better thermal shock resistance and more excellent hot corrosion resistance as compared with ZrO 2 coating materials without SiO 2 ;the improvement in performance of ZrO 2 coating doped with SiO 2 is due to forming more dense coating structure by self closing effects of the flaws and pores in the ZrO 2 coatings.
基金Project supported by the Science and Technology Department of Jiangsu Province(BE2016769)the Natural Science Foundation of China(51172107)+2 种基金Natural Science Foundation of the Jiangsu Higher Education Institutions of China(14KJB430014)Open fund by Jiangsu Engineering Technology Research Center of Environmental Cleaning Materials(KFK1503)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘NiMnO3 perovskite catalysts supported on cordierite modified by CexZr（1-x）O2 coatings were prepared using impregnation and sol-gel methods for catalytic combustion of single/double component VOCs at different concentrations and GHSV of 15,000 h^（-1）, which were characterized by BET, XRD, SEM, FT-IR, H2-TPR and O2-TPD. After coating modification, the specific surface area of catalysts is improved obviously.Among the catalysts, the Ce（0.75）Zr（0.25）O2 coating modified NiMnO3 catalyst exhibits the best catalytic activity for VOCs combustion with 95.6% conversion at 275 ℃ and has stable activity when catalyst is embalmed at 800 ℃. In addition, the catalyst also presents the excellent water-resistant and conversion stability over time-on-stream condition. The reason is that Ce（0.75）Zr（0.25）O2 coating can promote more lattice distortion and defects and smaller crystal size, which improve oxygen transfer capability and dispersion of active component.
文摘Ammonium nitrate(AN)is promising oxidizer in green propellants.In this work,the physical coating method was improved to modify the surface of ammonium nitrate particles with different surfactant materials to reduce hygroscopicity.Cetylalcohoi,stearic acid,stearyl alcohol,palmic acid,lauric acid,stearsmide,tetradecylamine,dodecylamine,and tetradecanol were used as coating surfactant agents.The hygroscopicity was tested for ammonium nitrate with and without coating.Fourier transform infrared(FTIR)and scanning electron microscopy(SEM)were used to characterize the surface of coated and uncoated ammonium nitrate.The mass ratio of coating layer and decline of absorption rate of ammonium nitrate coated by cetylalcohol were 1.00%,and 28.40%,respectively.The results indicate that coating with cetylalcohol surfactant have advantages over the other surfactants in term of low mass ratio of coating layer,and high decline of moisture absorption rate.Thus,cetylalcohol would be a promising coating surfactant material for ammonium nitrate.The idea and approach presented in this study have potential to made hydrophobic layer on the surface of particles to reduce hygroscopicity of AN,and also help the researcher to improving anti-hygroscopicity of ammonium salts.
基金Project supported by the National Natural Science Foundation of China (20572064) and the Natural Science Foundation of Shandong Province (Y2002G11)
文摘The coating of ZnS∶Mn by Sb-doped SnO2 using an co-precipitation process was reported. ZnS∶Mn phosphor particles were prepared by solid reaction with ZnS and MnCl2·4H2O. Surface modification of the ZnS∶Mn powders was carried out by coating transparent conductive films of Sb-doped tin oxides which were formed by co-precipitation and heat treatment process. Tin tetrachloride and antimony trichloride were used as the precursor materials for the co-precipitation. The influences of coating molar ratio, Sb concentration in the coatings, annealing temperature and time on the resistivity of coated ZnS∶Mn phosphors were investigated. The optimum co-precipitation processing parameters and annealing conditions were determined. The phosphors were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), photoluminescence(PL) observation and conductance measurements. An improvement in phosphors conductivity was observed while the respective photoluminescence intensity is analogous to the as-prepared ZnS∶Mn phosphors.
文摘A kind of modifier was synthesized to modify the surface of nanometer calcium carbonate （abbreviated as nano-CaCO3）, which is used in architectural coatings. The modification technology of the nano-CaCO3 was studied through orthogonal experimental methods. The factors studied were rotation speed, modifier dosage, emulsification temperature, emulsification time and heat aging time after emulsification. Optimized conditions for modification of the surface were： rotation speed 16000 r/min; modifier dosage 3%; emulsification temperature 75 ℃; emulsification time 60 min and aging time 40 min. The modified nano-CaCO3 was also studied by size-distribution measurements, transmission electron microscopy, infrared spectroscopy and thermal analysis. The results show that the size distribution of the modified nano-CaCO3 is uniform and that there are chemi-sorption and physi-sorption between the nano-CaCO3 and the modifier. Compared to traditional architectural coatings without nano-CaCO3, the nanometer composite coatings are obviously improved in respect to dirt resistance, scrub resistance, thixotropy, water resistance, alkalinity resistance and aging resistance.
基金supported by the National Natural Science Foundation of China (No.82101062)the Medical Health Science and Technology Project of Zhejiang Provincial Health Commission (No.2023KY132)the Zhejiang Provincial Key Research and Development Program of China (No.2021C03113).
文摘Silk fibroin(SF)as a natural biopolymer has become a popular material for biomedical applications due to its minimal immunogenicity,tunable biodegradability,and high biocompatibility.Nowadays,various techniques have been developed for the applications of SF in bioengineering.Most of the literature reviews focus on the SF-based biomaterials and their different forms of applications such as films,hydrogels,and scaffolds.SF is also valuable as a coating on other substrate materials for biomedicine;however,there are few reviews related to SF-coated biomaterials.Thus,in this review,we focused on the surface modification of biomaterials using SF coatings,demonstrated their various preparation methods on substrate materials,and introduced the latest procedures.The diverse applications of SF coatings for biomedicine are discussed,including bone,ligament,skin,mucosa,and nerve regeneration,and dental implant surface modification.SF coating is conducive to inducing cell adhesion and migration,promoting hydroxyapatite(HA)deposition and matrix mineralization,and inhibiting the Notch signaling pathway,making it a promising strategy for bone regeneration.In addition,SF-coated composite scaffolds can be considered prospective candidates for ligament regeneration after injury.SF coating has been proven to enhance the mechanical properties of the substrate material,and render integral stability to the dressing material during the regeneration of skin and mucosa.Moreover,SF coating is a potential strategy to accelerate nerve regeneration due to its dielectric properties,mechanical flexibility,and angiogenesis promotion effect.In addition,SF coating is an effective and popular means for dental implant surface modification to promote osteogenesis around implants made of different materials.Thus,this review can be of great benefit for further improvements in SF-coated biomaterials,and will undoubtedly contribute to clinical transformation in the future.
基金supported by the National Science and Technology Major Project(No.J2019-IV-0006-0074)the Key Research Program of the Chinese Academy of Sciences(No.ZDRW-CN-2021-2-2)+2 种基金the National Natural Science Foundation of China(No.52301116)support by the Joint Funds of the National Natural Science Foundation of China(“Ye Qisun”Science Funds,No.U2241251)the Innovation Engineering Project(No.211-XXXX-N106-01).
文摘To prolong the service lifetime of hot-section components used in marine environment at elevated tem-peratures,it is crucial to explore and develop high-temperature corrosion-resistant coatings.High-velocity oxygen fuel(HVOF)sprayed NiCoCrAlY,Pt-modified NiCoCrAlY and pre-oxidized Pt-modified NiCoCrAlY coatings were prepared and investigated.This study is concerned with the performance of three coat-ings in a simulated marine environment based on the phase composition of corrosion products and mi-crostructure evolution of coating samples combined with first-principles density functional theory.The results show that the NiCoCrAlY coating was subject to accelerated corrosion and extensive aluminum depletion,leading to premature coating failure.The high-temperature corrosion resistance of Pt-modified NiCoCrAlY coating was found to be better than that of NiCoCrAlY coating.In contrast,the pre-oxidized Pt-modified NiCoCrAlY coating offered long-lasting protection and exhibited the best corrosion resistance,which is attributed to the positive synergistic effect between Pt modification and pre-oxidation.
