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
A Cr/CoNiCrAlTaY bilayer coating was prepared on the Ti-45Al-8.5Nb alloy by plasma surface metallurgy technique.The as-prepared coating with a grain size of~2μm exhibited a dense microstructure and strong adhesion du...A Cr/CoNiCrAlTaY bilayer coating was prepared on the Ti-45Al-8.5Nb alloy by plasma surface metallurgy technique.The as-prepared coating with a grain size of~2μm exhibited a dense microstructure and strong adhesion due to metallurgical bonding,consisting of outermost Cr layer and CoNiCrAlTaY transition layer.The typical power-law relationship between mass gain and time was obtained for the coated specimens with a rate exponent of 3.18 following oxidation at 1173 K.The top Cr_(2)O_(3)film and spinel oxides(i.e.,NiCr_(2)O_(4)and CoCr_(2)O_(4))exhibited a protective effect with a low oxidation reaction rate.Interfacial analysis identified Ta precipitates(Cr_(2)Ta and TaAl_(3))and Ta oxides(Ta_(2)O_(5)and Ta_(2)O_(3)),which played an essential role in retarding rapid diffusion and enhancing adhesion and oxidation resistance.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
In order to improve the corrosion resistance of carbon steel,Hastelloy coatings were prepared on E235steel substrate by ahigh power diode laser with laser scanning speeds of6and12mm/s,respectively.The interface betwee...In order to improve the corrosion resistance of carbon steel,Hastelloy coatings were prepared on E235steel substrate by ahigh power diode laser with laser scanning speeds of6and12mm/s,respectively.The interface between the coating and substratewas firstly exposed by dissolving off the substrate.Its microstructure,composition and mechanical properties were systemicallystudied.Special“edges”along the grain boundary were found at coating/substrate interface.These“edges”consisted of intergranularcorrosion area and real grain boundary.The interface of coating mainly displayed austenite structure ascribed to the rapidsolidification as well as the dilution of Ni during preparation.Additionally,Hastelloy coating and its interface prepared at the speedof12mm/s showed higher hardness than that prepared at the speed of6mm/s.Grain boundaries had higher friction coefficient thangrains at both coating/substrate interfaces.Moreover,the interface at higher laser scanning speed exhibited smaller grains,lowerdilution rates of Ni and Fe as well as a better tribological property.展开更多
This work used the in-situ synthesis of molten-state nitride ceramic phase-reinforced Ni-based alloy coat-ings,aiming to improve the phase-interface bonding through the interdependent co-solidification be-tween molten...This work used the in-situ synthesis of molten-state nitride ceramic phase-reinforced Ni-based alloy coat-ings,aiming to improve the phase-interface bonding through the interdependent co-solidification be-tween molten droplets.The XRD was used to analyze the physical phases of the composite coatings.The microstructure and phase-interface structure were characterized in detail by combining SEM,TEM,HRTEM,FFT,and SAED techniques.Microhardness tester and microforce microhardness tester were em-ployed to measure the surface hardness and elastic modulus of the composite coatings.The fracture be-havior of the composite coatings was characterized by observing the fracture morphology of the coatings using SEM combined with the EDS technique.It was found that the formation mechanisms of inter-facial misfit dislocation assistance,lattice distortion,aggregation of stacking faults,and specific growth orientation between theγ-Ni matrix phase and each ceramic phase in NiCrBSi-TiCrN composite coat-ings improved the lattice matching between the two-phase interface,which resulted in the formation of atomically corresponding coherent lattice relations and stepped interfacial semi-coherent lattice relations,and enhanced the degree of phase-interface bonding.On this basis,the composite coatings with high Cr content further inhibited the expansion of interphase penetration cracks due to the existence of Cr-rich zones at the phase interface,thus exhibiting high fracture toughness.This work provides new opinions on the improvement of phase-interface bonding and composition design of Ni-based composite coatings.展开更多
In this paper, we deposited carbides on copper substrate by High velocity oxy-fuel (HVOF) spraying. The structure of the coating and microstructure of the substrate-coating interface have been investigated by means of...In this paper, we deposited carbides on copper substrate by High velocity oxy-fuel (HVOF) spraying. The structure of the coating and microstructure of the substrate-coating interface have been investigated by means of scanning electron microscope (SEM) and transmission electron microscopy (TEM). We observed the worn surface of the coating and investigated the wear mechanism. The results show that the microstructure of the interface between HVOF sprayed coating and substrate which consists of the amorphous layers, nanocrystalls in the coating and dislocation cells in copper substrate, etc. is complex. The amorphous layers are formed from heated adhesion after rapidly cooling, while the nanocrystalls come from the fragmentation of half-molten carbides. At the same time we found that the wear-resistant properties of the WC-Co coating is better than that of Cr3C2-NiCr coating at room temperature. The early wear-resistance of the HVOF sprayed coating is poor because of the roughness of its surface or bad bond of hard composite particles. The high velocity of molten droplets is propitious to fill up the interspaces between carbides, so as to make the coating more compact and reduce its porosities, thus the wear-resistance of carbides coatings is improved.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
The reliability of the coated industry components demands ideal fatigue properties of the coating,and it is mainly determined by the performance of the interfaces.In this study,pulsed magnetic treatment(PMT)was applie...The reliability of the coated industry components demands ideal fatigue properties of the coating,and it is mainly determined by the performance of the interfaces.In this study,pulsed magnetic treatment(PMT)was applied to the thermal sprayed WC-10Co4Cr coating,and the fatigue lifetime of the coated bolt increased by 219.82%under an imitation of the operating mode condition.Scratch tests further proved that both the adhesion and cohesion strength were improved after PMT,and they benefit from the interface strengthening effects.The formation of coherent WC/Co interfaces was characterized by in-situ transmission electron microscopy(TEM),and the molecular dynamic simulations indicate that the work of separation of these interfaces is much higher than the original disordered ones.Residual stress was relaxed and distributed more homogeneously after PMT,and it mainly contributes to the coating/substrate strengthening.This work provides a new post-treatment method focusing on the interfaces in the WC-based coating and gives insight into its mechanism so that it is hopeful to be applied to other kinds of coatings.展开更多
This paper mainly introduces the research progress on interface failure behavior in high-temperature alloy surface thermal barrier coating systems.The degradation failure and structural evolution behavior during high-...This paper mainly introduces the research progress on interface failure behavior in high-temperature alloy surface thermal barrier coating systems.The degradation failure and structural evolution behavior during high-temperature service were analyzed for the matrix/bonding layer interface,bonding layer/TGO interface,and TGO/ceramic layer interface in thermal barrier coatings.The research focus and direction that affect the interface performance of thermal barrier coatings were proposed.展开更多
The cross-sectional indentation method is extended to evaluate the interfacial adhesion between brittle coating and ductile substrate. The experimental results on electroplated chromium coating/steel substrate show th...The cross-sectional indentation method is extended to evaluate the interfacial adhesion between brittle coating and ductile substrate. The experimental results on electroplated chromium coating/steel substrate show that the interfacial separation occurs due to the edge chipping of brittle coating. The corresponding models are established to elucidate interfacial separation processes. This work further highlights the advantages and potential of this novel indentation method.展开更多
A novel test method of measuring the interface bond strength between a thermal sprayed coating and substrate is put forward first in this paper. The test method is simple and reliable, and exists no any inherent short...A novel test method of measuring the interface bond strength between a thermal sprayed coating and substrate is put forward first in this paper. The test method is simple and reliable, and exists no any inherent shortcoming and controversy. The interface bond strength obtained by the test method is completely the inherent property of the interface and depends only on coating material properties, spray conditions, and technique of depositing the coating. By extensive tests, it is shown that the test tesults are very tepeatable and reliable. Furthermore, from this test, the critical coating thickness under which the coating spall can not emerge is also obtained.展开更多
Micron-sized silicon anodes offer significant industrial advantages over nanoscale counterparts due to their cost-effectiveness and scalability.However,their practical applications are significantly hindered by severe...Micron-sized silicon anodes offer significant industrial advantages over nanoscale counterparts due to their cost-effectiveness and scalability.However,their practical applications are significantly hindered by severe stress-induced fragmentation,leading to rapid capacity decay.Addressing this challenge,we introduce a novel dual-conformal encapsulated micron-sized porous Si(μm-pSi)anode by utilizingμm-Si recycled from the photovoltaic industry as the Si precursor.This encapsulation design of the internal conformal SiO_(x)/C layer and external Ti_(3)C_(2)Tx MXene layer forms intergranular and intragranular protective skins onμm-pSi,ensuring simultaneous mechanical and electrochemical stability for efficient Li+storage.As a result,the fabricated WpSi@SiO_(x)/C@MXene anode demonstrates an exceptional cycling performance,delivering 535.1 mA h g^(−1)after 1500 cycles at 5 A g^(−1)with a minimal capacity decay of 0.003%per cycle.Chemo-mechanical modeling and SEI analysis reveal that the dual-conformal coating achieves exceptional mechanical and electrochemical stability through robust mechanical confinement and ultra-fast Li+diffusion kinetics during lithiation,coupled with a Li_(2)CO_(3)/LiF-rich hybrid SEI that facilitates Li+transport,collectively enabling rate-insensitive stress evolution,long-term structural durability,and stable cycling under high-rate conditions.This work provides a compelling design strategy for leveraging sustainableμm-Si to achieve high-rate and long-life lithium-ion batteries.展开更多
Ni-based coating,a kind of surface material,is characterized by high hardness,outstanding wear resistance,and excellent corrosion resistance.Ni-based coatings doped with hard phases can improve the coating quality.Thi...Ni-based coating,a kind of surface material,is characterized by high hardness,outstanding wear resistance,and excellent corrosion resistance.Ni-based coatings doped with hard phases can improve the coating quality.This is an important topic in related fields.Compared with traditional Ni-based coatings,Ni-based coatings doped with a hard phase have stronger competitive advantages.Among these,Ni-based diamond composite coatings have superior performance.Hence,it has become a kind of excellent functional coating.We outline the current state of research on Ni-based diamond composite coatings.Advances in seven preparation processes for Ni-based diamond composite coatings were discussed.These processes mainly include brazing,electrodeposition,sintering,laser cladding,plasma spraying,supersonic laser deposition,and vacuum cladding.The latest studies on the interfacial behavior,microstructure,and bond strength of these composite coatings are also summarized.The deficiencies for present Ni-based diamond composite coatings are pointed out.Meanwhile,the developmental directions of related fields are envisioned.That could provide theoretical guidance and reference information for research and technological development in the near future.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
There has been much interest in developing multilayered or nanolayered physical vapor deposition（PVD） coatings identified as a group of promising protective coatings for their excellent mechanical properties and cor...There has been much interest in developing multilayered or nanolayered physical vapor deposition（PVD） coatings identified as a group of promising protective coatings for their excellent mechanical properties and corrosion resistance. In this study, the multilayered Cr N/Cr2O3 coatings with different bilayer periods（L） were synthesized on the polished high speed steel substrates from a Cr target with the alternative atmosphere of pure nitrogen and pure oxygen by arc ion plating（AIP） technique. The results revealed that the microstructure,morphologies and properties of the multilayered coatings were strongly influenced by the bilayer period（L）.There were two kinds of interfaces in the multilayered Cr N/Cr2O3coatings： the sharp ones and the blurry ones. With reducing the value of L, the macro-particles densities decreased gradually, whereas the coating microhardness, adhesive strength and wear resistance first increased, and then decreased slightly or remained stable as the bilayer period L 〈 590 nm. The multilayered Cr N/Cr2O3 coating with the bilayer period L of 590 nm possessed the best comprehensive properties, namely the highest microhardness, the strongest adhesion, and the lowest wear rate.展开更多
The heterogeneous multilayer interface of VN/Ag coatings and transition multilayer interface of VN/Ag coatings were prepared on Inconel 781 and Si(100),and the microstructures,mechanical and tribological properties we...The heterogeneous multilayer interface of VN/Ag coatings and transition multilayer interface of VN/Ag coatings were prepared on Inconel 781 and Si(100),and the microstructures,mechanical and tribological properties were investigated from 25 to 700℃.The results showed that the surface roughness and average grain size of VN/Ag coatings with transition multilayer interface are obviously larger than those of VN/Ag coatings with heterogeneous multilayer interface.The coatings with transition multilayer interface have higher adhesion force and hardness than the coatings with heterogeneous multilayer interface,and both coatings can effectively restrict the initiation and propagation of microcracks.Both coatings have excellent self-adaptive lubricating properties with a decrease of friction coefficient as the temperature increases,but their wear rates reveal a drastic increase.The phase composition of the worn area of both coatings was investigated,which indicates that a smooth Ag,Magnéli phase(V2O5)and bimetallic oxides(Ag3VO4 and AgVO3)can be responsible to the excellent lubricity of both coatings.To sum up,the coatings with transition multilayer interface have excellent adaptive lubricating properties and can properly control the diffusion rate and release rate of the lubricating phase,indicating that they have great potential in solving the problem of friction and wear of mechanical parts.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
Based on the three-phase model, the propagation behavior of a matrix crack in an intelligent coating system is investigated by an energy criterion. The effect of the elastic mismatch parameters and the thickness of th...Based on the three-phase model, the propagation behavior of a matrix crack in an intelligent coating system is investigated by an energy criterion. The effect of the elastic mismatch parameters and the thickness of the interface layer on the ratio of the energy release rate for infinitesimal deflected and penetrated crack is evaluated with the finite element method. The results show that the ratio of the energy release rates strongly depends on the elastic mismatch al between the substrate and the driving layer. It also strongly depends on the elastic mismatch a2 between the driving layer and the sensing layer for a thinner driving layer when a primary crack reaches an interface between the substrate and the driving layer. Moreover, with the increase in the thickness of the driving layer, the dependence on a2 gradually decreases. The experimental observation on aluminum alloys monitored with intelligent coating shows that the established model can better explain the behavior of matrix crack penetration and can be used in optimization design of intelligent coating.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
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financial supports from Shanxi Provincial Natural Science Foundation,China(No.20210302123162)Shanxi Scholarship Council of China(No.2024-057)+2 种基金State Key Laboratory of Advanced Metal Materials,China(No.2019-ZD02)Science and Technology Achievement Transformation and Cultivation Project of Shanxi,China(No.2020CG011)Shanxi“1331 Project”Quality Improvement and Efficiency Project,China。
文摘A Cr/CoNiCrAlTaY bilayer coating was prepared on the Ti-45Al-8.5Nb alloy by plasma surface metallurgy technique.The as-prepared coating with a grain size of~2μm exhibited a dense microstructure and strong adhesion due to metallurgical bonding,consisting of outermost Cr layer and CoNiCrAlTaY transition layer.The typical power-law relationship between mass gain and time was obtained for the coated specimens with a rate exponent of 3.18 following oxidation at 1173 K.The top Cr_(2)O_(3)film and spinel oxides(i.e.,NiCr_(2)O_(4)and CoCr_(2)O_(4))exhibited a protective effect with a low oxidation reaction rate.Interfacial analysis identified Ta precipitates(Cr_(2)Ta and TaAl_(3))and Ta oxides(Ta_(2)O_(5)and Ta_(2)O_(3)),which played an essential role in retarding rapid diffusion and enhancing adhesion and oxidation resistance.
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Project supported by the New Staff Research Start-up Fund and the Innovation Fund(School of Materials Science and Engineering) of Southwest Petroleum University,China
文摘In order to improve the corrosion resistance of carbon steel,Hastelloy coatings were prepared on E235steel substrate by ahigh power diode laser with laser scanning speeds of6and12mm/s,respectively.The interface between the coating and substratewas firstly exposed by dissolving off the substrate.Its microstructure,composition and mechanical properties were systemicallystudied.Special“edges”along the grain boundary were found at coating/substrate interface.These“edges”consisted of intergranularcorrosion area and real grain boundary.The interface of coating mainly displayed austenite structure ascribed to the rapidsolidification as well as the dilution of Ni during preparation.Additionally,Hastelloy coating and its interface prepared at the speedof12mm/s showed higher hardness than that prepared at the speed of6mm/s.Grain boundaries had higher friction coefficient thangrains at both coating/substrate interfaces.Moreover,the interface at higher laser scanning speed exhibited smaller grains,lowerdilution rates of Ni and Fe as well as a better tribological property.
基金supported by the National Natural Science Foundation of China(No.52271055)the Natural Science Foundation of Hebei Province(No.E2021202130).
文摘This work used the in-situ synthesis of molten-state nitride ceramic phase-reinforced Ni-based alloy coat-ings,aiming to improve the phase-interface bonding through the interdependent co-solidification be-tween molten droplets.The XRD was used to analyze the physical phases of the composite coatings.The microstructure and phase-interface structure were characterized in detail by combining SEM,TEM,HRTEM,FFT,and SAED techniques.Microhardness tester and microforce microhardness tester were em-ployed to measure the surface hardness and elastic modulus of the composite coatings.The fracture be-havior of the composite coatings was characterized by observing the fracture morphology of the coatings using SEM combined with the EDS technique.It was found that the formation mechanisms of inter-facial misfit dislocation assistance,lattice distortion,aggregation of stacking faults,and specific growth orientation between theγ-Ni matrix phase and each ceramic phase in NiCrBSi-TiCrN composite coat-ings improved the lattice matching between the two-phase interface,which resulted in the formation of atomically corresponding coherent lattice relations and stepped interfacial semi-coherent lattice relations,and enhanced the degree of phase-interface bonding.On this basis,the composite coatings with high Cr content further inhibited the expansion of interphase penetration cracks due to the existence of Cr-rich zones at the phase interface,thus exhibiting high fracture toughness.This work provides new opinions on the improvement of phase-interface bonding and composition design of Ni-based composite coatings.
基金Financial support from Natural Science Foundation of Shanxi Province(grants No.20011044)Youth Technologic Foundation of Shanxi Province(grants No.20041023)is gratefully acknowledged.
文摘In this paper, we deposited carbides on copper substrate by High velocity oxy-fuel (HVOF) spraying. The structure of the coating and microstructure of the substrate-coating interface have been investigated by means of scanning electron microscope (SEM) and transmission electron microscopy (TEM). We observed the worn surface of the coating and investigated the wear mechanism. The results show that the microstructure of the interface between HVOF sprayed coating and substrate which consists of the amorphous layers, nanocrystalls in the coating and dislocation cells in copper substrate, etc. is complex. The amorphous layers are formed from heated adhesion after rapidly cooling, while the nanocrystalls come from the fragmentation of half-molten carbides. At the same time we found that the wear-resistant properties of the WC-Co coating is better than that of Cr3C2-NiCr coating at room temperature. The early wear-resistance of the HVOF sprayed coating is poor because of the roughness of its surface or bad bond of hard composite particles. The high velocity of molten droplets is propitious to fill up the interspaces between carbides, so as to make the coating more compact and reduce its porosities, thus the wear-resistance of carbides coatings is improved.
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.
基金This study was financially supported by National Key R&D Program of China(No.2020YFA0714900)National Natural Science Foundation of China(No.52031003)the Defense Industrial Technology Development Program(No.JCKY2020110B007).
文摘The reliability of the coated industry components demands ideal fatigue properties of the coating,and it is mainly determined by the performance of the interfaces.In this study,pulsed magnetic treatment(PMT)was applied to the thermal sprayed WC-10Co4Cr coating,and the fatigue lifetime of the coated bolt increased by 219.82%under an imitation of the operating mode condition.Scratch tests further proved that both the adhesion and cohesion strength were improved after PMT,and they benefit from the interface strengthening effects.The formation of coherent WC/Co interfaces was characterized by in-situ transmission electron microscopy(TEM),and the molecular dynamic simulations indicate that the work of separation of these interfaces is much higher than the original disordered ones.Residual stress was relaxed and distributed more homogeneously after PMT,and it mainly contributes to the coating/substrate strengthening.This work provides a new post-treatment method focusing on the interfaces in the WC-based coating and gives insight into its mechanism so that it is hopeful to be applied to other kinds of coatings.
文摘This paper mainly introduces the research progress on interface failure behavior in high-temperature alloy surface thermal barrier coating systems.The degradation failure and structural evolution behavior during high-temperature service were analyzed for the matrix/bonding layer interface,bonding layer/TGO interface,and TGO/ceramic layer interface in thermal barrier coatings.The research focus and direction that affect the interface performance of thermal barrier coatings were proposed.
文摘The cross-sectional indentation method is extended to evaluate the interfacial adhesion between brittle coating and ductile substrate. The experimental results on electroplated chromium coating/steel substrate show that the interfacial separation occurs due to the edge chipping of brittle coating. The corresponding models are established to elucidate interfacial separation processes. This work further highlights the advantages and potential of this novel indentation method.
文摘A novel test method of measuring the interface bond strength between a thermal sprayed coating and substrate is put forward first in this paper. The test method is simple and reliable, and exists no any inherent shortcoming and controversy. The interface bond strength obtained by the test method is completely the inherent property of the interface and depends only on coating material properties, spray conditions, and technique of depositing the coating. By extensive tests, it is shown that the test tesults are very tepeatable and reliable. Furthermore, from this test, the critical coating thickness under which the coating spall can not emerge is also obtained.
基金the financial support from the Natural Science Foundation of Shanghai(23ZR1423800)Open Research Fund of Shanghai Key Laboratory of Green Chemistry and Chemical Processes(East China Normal University,202503)+1 种基金State Key Laboratory of Advanced Fiber Materials(Donghua University,KF2406)Key Laboratory of Advanced Energy Materials Chemistry(Ministry of Education),Nankai University。
文摘Micron-sized silicon anodes offer significant industrial advantages over nanoscale counterparts due to their cost-effectiveness and scalability.However,their practical applications are significantly hindered by severe stress-induced fragmentation,leading to rapid capacity decay.Addressing this challenge,we introduce a novel dual-conformal encapsulated micron-sized porous Si(μm-pSi)anode by utilizingμm-Si recycled from the photovoltaic industry as the Si precursor.This encapsulation design of the internal conformal SiO_(x)/C layer and external Ti_(3)C_(2)Tx MXene layer forms intergranular and intragranular protective skins onμm-pSi,ensuring simultaneous mechanical and electrochemical stability for efficient Li+storage.As a result,the fabricated WpSi@SiO_(x)/C@MXene anode demonstrates an exceptional cycling performance,delivering 535.1 mA h g^(−1)after 1500 cycles at 5 A g^(−1)with a minimal capacity decay of 0.003%per cycle.Chemo-mechanical modeling and SEI analysis reveal that the dual-conformal coating achieves exceptional mechanical and electrochemical stability through robust mechanical confinement and ultra-fast Li+diffusion kinetics during lithiation,coupled with a Li_(2)CO_(3)/LiF-rich hybrid SEI that facilitates Li+transport,collectively enabling rate-insensitive stress evolution,long-term structural durability,and stable cycling under high-rate conditions.This work provides a compelling design strategy for leveraging sustainableμm-Si to achieve high-rate and long-life lithium-ion batteries.
基金financially supported by the National Program of Foreign Experts of China(G2023026003L)the National Natural Science Foundation of China(52475347,52071165,51705151)+4 种基金China Postdoctoral Fund(2023M740475)sponsored by the Program for Science&Technology Innovation Talents in Universities of Henan Province,China(22HASTIT026)International Science and Technology Cooperation Project of Henan Province(242102521057),Chinasupported by the Program for the Top Young Talents of Henan Province,ChinaFrontier Exploration Project of Longmen Laboratory(LMQYTSKT016),China.
文摘Ni-based coating,a kind of surface material,is characterized by high hardness,outstanding wear resistance,and excellent corrosion resistance.Ni-based coatings doped with hard phases can improve the coating quality.This is an important topic in related fields.Compared with traditional Ni-based coatings,Ni-based coatings doped with a hard phase have stronger competitive advantages.Among these,Ni-based diamond composite coatings have superior performance.Hence,it has become a kind of excellent functional coating.We outline the current state of research on Ni-based diamond composite coatings.Advances in seven preparation processes for Ni-based diamond composite coatings were discussed.These processes mainly include brazing,electrodeposition,sintering,laser cladding,plasma spraying,supersonic laser deposition,and vacuum cladding.The latest studies on the interfacial behavior,microstructure,and bond strength of these composite coatings are also summarized.The deficiencies for present Ni-based diamond composite coatings are pointed out.Meanwhile,the developmental directions of related fields are envisioned.That could provide theoretical guidance and reference information for research and technological development in the near future.
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financial supports from the National Key Basic Research Program of China (973 Program, No. 2012CB625100)the National Natural Science Foundation of China (Nos. 51001106 and 51301181)the Doctoral Starting up Foundation of Liaoning Province Science and Technology Agency, China (No. 20131118)
文摘There has been much interest in developing multilayered or nanolayered physical vapor deposition（PVD） coatings identified as a group of promising protective coatings for their excellent mechanical properties and corrosion resistance. In this study, the multilayered Cr N/Cr2O3 coatings with different bilayer periods（L） were synthesized on the polished high speed steel substrates from a Cr target with the alternative atmosphere of pure nitrogen and pure oxygen by arc ion plating（AIP） technique. The results revealed that the microstructure,morphologies and properties of the multilayered coatings were strongly influenced by the bilayer period（L）.There were two kinds of interfaces in the multilayered Cr N/Cr2O3coatings： the sharp ones and the blurry ones. With reducing the value of L, the macro-particles densities decreased gradually, whereas the coating microhardness, adhesive strength and wear resistance first increased, and then decreased slightly or remained stable as the bilayer period L 〈 590 nm. The multilayered Cr N/Cr2O3 coating with the bilayer period L of 590 nm possessed the best comprehensive properties, namely the highest microhardness, the strongest adhesion, and the lowest wear rate.
基金Project(51505100)supported by the National Natural Science Foundation of China
文摘The heterogeneous multilayer interface of VN/Ag coatings and transition multilayer interface of VN/Ag coatings were prepared on Inconel 781 and Si(100),and the microstructures,mechanical and tribological properties were investigated from 25 to 700℃.The results showed that the surface roughness and average grain size of VN/Ag coatings with transition multilayer interface are obviously larger than those of VN/Ag coatings with heterogeneous multilayer interface.The coatings with transition multilayer interface have higher adhesion force and hardness than the coatings with heterogeneous multilayer interface,and both coatings can effectively restrict the initiation and propagation of microcracks.Both coatings have excellent self-adaptive lubricating properties with a decrease of friction coefficient as the temperature increases,but their wear rates reveal a drastic increase.The phase composition of the worn area of both coatings was investigated,which indicates that a smooth Ag,Magnéli phase(V2O5)and bimetallic oxides(Ag3VO4 and AgVO3)can be responsible to the excellent lubricity of both coatings.To sum up,the coatings with transition multilayer interface have excellent adaptive lubricating properties and can properly control the diffusion rate and release rate of the lubricating phase,indicating that they have great potential in solving the problem of friction and wear of mechanical parts.
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.
基金Project supported by the National Natural Science Foundation of China(No.51175404)
文摘Based on the three-phase model, the propagation behavior of a matrix crack in an intelligent coating system is investigated by an energy criterion. The effect of the elastic mismatch parameters and the thickness of the interface layer on the ratio of the energy release rate for infinitesimal deflected and penetrated crack is evaluated with the finite element method. The results show that the ratio of the energy release rates strongly depends on the elastic mismatch al between the substrate and the driving layer. It also strongly depends on the elastic mismatch a2 between the driving layer and the sensing layer for a thinner driving layer when a primary crack reaches an interface between the substrate and the driving layer. Moreover, with the increase in the thickness of the driving layer, the dependence on a2 gradually decreases. The experimental observation on aluminum alloys monitored with intelligent coating shows that the established model can better explain the behavior of matrix crack penetration and can be used in optimization design of intelligent coating.
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.
