When micro/nano-scale gradient coatings are subject to large thermal gradients or high heat fluxes,the spatial size effect cannot be ignored.It is important to understand how the size effect influences the thermal fra...When micro/nano-scale gradient coatings are subject to large thermal gradients or high heat fluxes,the spatial size effect cannot be ignored.It is important to understand how the size effect influences the thermal fracture behavior of functionally graded coating/substrate structures.This study aims at analyzing the transient thermal fracture behavior of collinear interface cracks in functionally graded coating/substrate structures based on the nonlocal dual-phase-lag heat conduction model.By means of integral transform techniques,the mixed boundary problem is transformed into a set of singular integral equations,which are solved by the Chebyshev polynomials.The effects of the nonlocal parameter,coating thickness,crack spacing,and non-homogeneous parameters on the temperature and stress intensity factors(SIFs)are examined.The numerical results show that these parameters play an essential role in controlling the thermal fracture behavior of the structures,especially at micro/nano-scales.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
To mitigate the impact of interdiffusion reactions between the silicide slurry and Ta12W alloy substrate during vacuum sintering process on the oxidation resistance of the silicide coating,a micro-arc oxidation pretre...To mitigate the impact of interdiffusion reactions between the silicide slurry and Ta12W alloy substrate during vacuum sintering process on the oxidation resistance of the silicide coating,a micro-arc oxidation pretreatment was employed to construct a Ta_(2)O_(5)ceramic layer on the Ta12W alloy surface.Subsequently,a slurry spraying-vacuum sintering method was used to prepare a Si-Cr-Ti-Zr coating on the pretreated substrate.Comparative studies were conducted on the microstructure,phase composition,and isothermal oxidation resistance(at 1600℃)of the as-prepared coatings with and without the micro-arc oxidation ceramic layer.The results show that the Ta_(2)O_(5)layer prepared at 400 V is more continuous and has smaller pores than that prepared at 350 V.After microarc oxidation pretreatment,the Si-Cr-Ti-Zr coating on Ta12W alloy consists of three distinct layers:an upper layer dominated by Ti_(5)Si_(3),Ta_(5)Si_(3),and ZrSi;a middle layer dominated by TaSi_(2);a coating/substrate interfacial reaction layer dominated by Ta_(5)Si_(3).Both the Si-Cr-Ti-Zr coatings with and without the Ta_(2)O_(5)ceramic layer do not fail after isothermal oxidation at 1600℃for 5 h.Notably,the addition of the Ta2O5 ceramic layer reduces the high-temperature oxidation rate of the coating.展开更多
Nanoporous polymers are extensively coated on various substrates to deliver optical,permselective,or other functions.However,it remains desired to fast produce uniform nanoporous polymer coatings on substrates with co...Nanoporous polymers are extensively coated on various substrates to deliver optical,permselective,or other functions.However,it remains desired to fast produce uniform nanoporous polymer coatings on substrates with complex surfaces.Herein,by manipulating the interactions between block copolymers and selective solvents,we prepare repairable nanoporous polymers on arbitrary substrates.This is realized by an extremely simple sequential coating process:sequential coating of block copolymers and their swelling agents on substrate surfaces.The swelling agents are comprised of two solvents that swell the constituent blocks of the copolymers to different degrees,rapidly producing polymer coatings with uniform,interconnected,sub-50 nm pores.This sequential coating process is able to conformally build nanoporous polymers on nonplanar substrates with large lateral sizes and complex surface features,and also to in situ repair defects arising during usages.We further demonstrate that the nanoporous coatings show excellent antireflective and membrane separation performances.This sequential coating process is dictated by polymer–solvent interactions,and is expected to find applications in diverse fields for its simplicity,adaptability,and the capability to produce well-defined nanoporosities.展开更多
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
Developing high-efficient flame-retardant coatings is crucial for fire safety polymer and battery fields.Traditional intumescent coatings and ceramifiable coatings struggle to provide immediate and prolonged protectio...Developing high-efficient flame-retardant coatings is crucial for fire safety polymer and battery fields.Traditional intumescent coatings and ceramifiable coatings struggle to provide immediate and prolonged protection simultaneously,which limits the applicability.To address this,an innovative bi-layered coating with organic/nano-inorganic additives is inspired by differential response behaviors,enabling relay response effect with both fast-acting and extended protection.Specifically,two layers function continuously in the form of a relay.With a mere 320 microns,the bi-layered coating withstands fire temperatures of up to 1400℃for at least 900 s.Consequently,the coating effective prevented burn through in aluminum plates and glass fabric-reinforced epoxy resin,which otherwise were burned through in 135 and 173 s,respectively.Meanwhile,the bi-layered coating suppressed the formation and decomposition of solid interface layer in lithium soft-package batteries,leading to prolonged electrochemical stability and fire safety.Additionally,the bi-layered coating with a fast response endows polyurethane foam with rapid self-extinguishing,preventing ignition even under exposure to strong fire of 1400℃.Shortly,our work offers new insights into the design and development of thin,high-performance,and multi-application flame-retardant coatings.展开更多
Fe-based coating was produced on pure Ti substrate by the laser cladding technology. The composition and microstructure of the fabricated coating were analyzed by scanning electron microscopy （SEM）, X-ray diffracti...Fe-based coating was produced on pure Ti substrate by the laser cladding technology. The composition and microstructure of the fabricated coating were analyzed by scanning electron microscopy （SEM）, X-ray diffraction （XRD） and transmission electron microscopy （TEM） technique. The tribological properties were tested through sliding against AISI52100 steel ball at different normal loads and sliding speeds. Besides, the morphologies of the worn surfaces and wear debris were analyzed by scanning electron microscopy （SEM） and three dimensional （3D） non-contact surface mapping. The results show that the prepared Fe-based coating has a high hardness of about 860 HV0.2 and exhibits an average wear rate of （0.70-2.32）×10-6 mm3/（N-m）, showing that the Fe-based coating can greatly improve the wear resistance of pure Ti substrate. The wear mechanism of the coating involves moderate adhesive and abrasive wear.展开更多
The outermost coating with single phase Ni2Al3 was obtained on copper surface by electrodepositing nickel followed by slurry pack aluminizing at 800 °C for 12 h. The oxidation resistance and microstructure of the...The outermost coating with single phase Ni2Al3 was obtained on copper surface by electrodepositing nickel followed by slurry pack aluminizing at 800 °C for 12 h. The oxidation resistance and microstructure of the coating oxidized in ambient air at 1000 °C for 25-250 h were investigated using SEM, X-ray diffraction and optical microscope methods. The results show that the copper with single phase Ni2Al3 coating possesses the best high temperature oxidation resistance, and the mass gain of the coating is 1/15 that of pure copper and 1/2 that of nickel coating, respectively. The specimen surface after being oxidized for 25 h still comprises Ni2Al3 phase. However, when the time of oxidizing treatment increases to 50 h, the Ni Al phase is formed. It is also found that the Ni2Al3 phase completely turns into Ni Al phase after oxidizing treatment for 100 h and above. The Ni Al coating shows excellent high temperature oxidation resistance when oxidation time is 250 h.展开更多
The propagation characteristics of laser-generated like-Rayleigh waves in viscoelastic adhesive coating/substrate structures were studied.Considering the viscoelasticity of the coating and substrate,we have establishe...The propagation characteristics of laser-generated like-Rayleigh waves in viscoelastic adhesive coating/substrate structures were studied.Considering the viscoelasticity of the coating and substrate,we have established the finite element models in frequency domain for the laser-generated like-Rayleigh waves in the epoxy coating/aluminum substrate,epoxy coating/brass substrate,and epoxy coating/foam substrate structures,respectively.In addition,we have investigated the waveform and propagation characteristics of the like-Rayleigh waves and studied the influences of the coating transparency,coating thickness,coating viscoelasticity,and substrate viscoelasticity on the propagation characteristics of the like-Rayleigh waves.Moreover,we have verified the results by the theoretical phase velocity and attenuation curves.The results show that the coating viscoelasticity induces the attenuation characteristics of the higher frequencies of the like-Rayleigh waves,but has little effect on the lower frequencies,and the substrate viscoelasticity has the influences on both the higher and lower frequencies of the like-Rayleigh waves,especially the lower frequencies.Furthermore,the mode and dispersive characteristics of the like-Rayleigh waves are closely related to the substrates.This study provides a useful theoretical basis for inverting mechanical parameters and evaluating the adhesive quality of the viscoelastic adhesive coating/substrate structures.展开更多
Ti/TiN/Zr/ZrN multilayer coatings were deposited on Cr_17Ni_2 steel substrates with different surface roughnesses by vacuum cathodic arc deposition method. Microstructure, micro-hardness, adhesion strength and cross-s...Ti/TiN/Zr/ZrN multilayer coatings were deposited on Cr_17Ni_2 steel substrates with different surface roughnesses by vacuum cathodic arc deposition method. Microstructure, micro-hardness, adhesion strength and cross-sectional morphology of the obtained multilayer coatings were investigated. The results show that the Vickers hardness of Ti/TiN/Zr/ZrN multilayer coating, with a film thickness of 11.37 μm, is 29.36 GPa. The erosion and salt spray resistance performance of Cr_17Ni_2 steel substrates can be evidently improved by Ti/TiN/Zr/ZrN multilayer coating. The surface roughness of Cr_17Ni_2 steel substrates plays an important role in determining the mechanical and erosion performances of Ti/TiN/Zr/ZrN multilayer coatings. Overall, a low value of the surface roughness of substrates corresponds to an improved performance of erosion and salt spray resistance of multilayer coatings. The optimized performance of Ti/TiN/Zr/ZrN multilayer coatings can be achieved provided that the surface roughness of Cr_17Ni_2 steel substrates is lower than 0.4μm.展开更多
Black nickel coatings have emerged as a research hotspot in materials science due to their excellent performance and broad application prospects.In this study,nickel-based black coatings were fabricated on low-carbon ...Black nickel coatings have emerged as a research hotspot in materials science due to their excellent performance and broad application prospects.In this study,nickel-based black coatings were fabricated on low-carbon steel substrates via photo-assisted electrodeposition.A systematic investigation was conducted on the effects of cerium ion concentration and nano-ceria(CeO_(2))particle content in the electrolyte on the coating properties,along with an analysis of the temporal evolution of coating’s corrosion resistance.When the cerium ion concentration in the electrolyte was 0.05 mol/L,the coating exhibited a uniform black appearance with a light absorption rate of 95%,an emissivity of 0.87,maximum impedance,and the lowest corrosion tendency,demonstrating optimal comprehensive performance.The coating prepared with a nano-ceria concentration of 6 g/L in the electrolyte exhibited an emissivity of 0.9,achieved a 5B adhesion grade(ASTM D3359-09),and demonstrated a one-order-of-magnitude reduction in corrosion current density compared to coatings fabricated without nano-ceria in the electrolyte.With prolonged storage time,the coating's impedance slightly increased,leading to improved corrosion resistance.展开更多
This paper investigates the functionally graded coating bonded to an elastic strip with a crack under thermal- mechanical loading. Considering some new boundary conditions, it is assumed that the temperature drop acro...This paper investigates the functionally graded coating bonded to an elastic strip with a crack under thermal- mechanical loading. Considering some new boundary conditions, it is assumed that the temperature drop across the crack surface is the result of the thermal conductivity index which controls heat conduction through the crack region. By the Fourier transforms, the thermal-elastic mixed boundary value problems are reduced to a system of singular integral equations which can be approximately solved by applying the Chebyshev polynomials. The numerical computation methods for the temperature, the displacement field and the thermal stress intensity factors （TSIFs） are presented. The normal temperature distributions （NTD） with different parameters along the crack surface are analyzed by numerical examples. The influence of the crack position and the thermal-elastic non- homogeneous parameters on the TSIFs of modes I and 11 at the crack tip is presented. Results show that the variation of the thickness of the graded coating has a significant effect on the temperature jump across the crack surfaces when keeping the thickness of the substrate constant, and the thickness of functionally graded material （FGM） coating has a significant effect on the crack in the substrate. The results can be expected to be used for the purpose of gaining better understanding of the thermal-mechanical behavior of graded coatings.展开更多
Carbon fiber-reinforced carbon aerogel(C/CA)composites are one of the most promising candidates for applications requiring both thermal insulation and load bearing capabilities.The preparation of anti-oxidation coatin...Carbon fiber-reinforced carbon aerogel(C/CA)composites are one of the most promising candidates for applications requiring both thermal insulation and load bearing capabilities.The preparation of anti-oxidation coatings on C/CA to address its susceptibility to oxidation is a feasible approach to promote its application in oxidative environments.However,the currently reported coatings on C/CA mainly focus on improving the ablation performance and coating preparation process typically necessitating high-temperature heat treatment.This procedure can increase its thermal conductivity and reduce its thermal insulation ability.In this study,a series of ceramic-resin coatings were fabricated on C/CA through a simple slurry brushing-drying approach at room temperature.The effects of phenolic resin content on the coating structure,residual stress,thermal shock,and oxidation behaviors were investigated.Due to the adhesive properties and curing-induced shrinkage,the PR-7.5 coating(containing 7.5%(in mass)phenolic resin in the slurry)exhibits bonding strength close to fracture strength of the substrate and residual compressive stress of 0.853 GPa,which is beneficial for resisting thermal shock cracking.However,excessive resin content(PR-10.0 containing 10.0%(in mass)phenolic resin in the slurry)induces tensile stress due to uneven curing shrinkage,thereby leading to thermal shock cracking.Meanwhile,oxidation tests reveal significantly reduced weight losses for PR-7.5(17.46%at 800℃/100 min,8.15%at 1000℃/120 min,3.15%at 1200℃/120 min)versus uncoated C/CA’s 44.60%loss at 800℃/20 min.This work provides a brand-new and simple approach to improving the anti-oxidation performance of C/CA and expands its application in mild oxidative environments.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 absence of large-size gallium nitride(GaN) substrates with low dislocation density remains a primary bottleneck for advancing GaN-based devices. Here, we demonstrate the achievement of 8-inch freestanding GaN subs...The absence of large-size gallium nitride(GaN) substrates with low dislocation density remains a primary bottleneck for advancing GaN-based devices. Here, we demonstrate the achievement of 8-inch freestanding GaN substrates grown by hydride vapor phase epitaxy. Critical to this achievement is the improvement in gas-flow uniformity, which ensures exceptional thickness homogeneity and enables the crack-free growth of GaN. After laser lift-off(LLO) separation, the freestanding GaN substrate exhibits superior crystal quality, evidenced by full width at half maximum values of 68 and 54 arcsec for X-ray diffraction rocking curves of(002) and(102) planes, alongside a low dislocation density of 1.6 × 10^(6) cm^(-2). This approach establishes a robust pathway for the production of large-size GaN substrates, which are essential for advancing next-generation power electronics and high-efficiency photonics.展开更多
Sporadic or late-onset Alzheimer’s disease(LOAD)occurs in 1 of 10 people over 65 years of age and comprises 95%of all AD patients.Unlike early-onset AD,which is caused by defined single gene mutations,the mechanisms ...Sporadic or late-onset Alzheimer’s disease(LOAD)occurs in 1 of 10 people over 65 years of age and comprises 95%of all AD patients.Unlike early-onset AD,which is caused by defined single gene mutations,the mechanisms and events underlying risk for LOAD are not fully understood and no substantial disease-modifying interventions are currently available.Age is the most prominent risk factor for LOAD,and interacting age-related and LOAD-associated factors contribute to its pathogenesis.Among these factors are changes in bioenergetic cell functions,which metabolize substrates and produce energy stored in adenosine triphosphate.展开更多
An advanced AlCrSiN/AlCrN/CrN/Cr multilayer coating was developed via hybrid multiarc ion plating and high-power impulse magnetron sputtering.The multilayer design enhanced the substrate-coating compatibility,achievin...An advanced AlCrSiN/AlCrN/CrN/Cr multilayer coating was developed via hybrid multiarc ion plating and high-power impulse magnetron sputtering.The multilayer design enhanced the substrate-coating compatibility,achieving a critical load of 87.8 N.Silicon doping induced nanocrystallization and amorphization,increasing the hardness to 26 GPa.At high temperatures,a nanoscale Cr-rich(Cr,Al)_(2)O_(3) layer was formed,effectively inhibiting oxygen diffusion.The coating underwent unique phase transformations,during which Cr_(2)N and amorphous Si3N4 were converted into dispersed SiCr_(3) nanoparticles,which stabilized Cr atoms and suppressed their outward diffusion.Ab initio molecular dynamics simulations revealed that Cr atoms exhibited higher chemical activity and oxygen-capture capability than Al atoms and Si atoms served as diffusion barriers by pinning onto the oxidized surface,considerably improving the oxidation resistance of the coating.展开更多
Substrate and nutrient supply are essential for vegetable cultivation in greenhouse.The strategies for plant nutrient supply vary depending on the cultivation methods or substrate dosages employed.With the development...Substrate and nutrient supply are essential for vegetable cultivation in greenhouse.The strategies for plant nutrient supply vary depending on the cultivation methods or substrate dosages employed.With the development of mechanization,wide-row spacing substrate cultivation became an optimize mode of the greenhouse cucumber cultivation,aligning with the trend of intelligent agriculture.To determine the optimal nutrient solution supply amount(NS)and supply frequency(SF)for promoting the integrated growth of cucumber under wide-row spacing substrate cultivation,we explored the effects of substrate supply amount(SS),NS,and SF on cucumber yield,quality,and element utilization efficiency.A five-level quadratic orthogonal rotation combination design with three experimental factors(NS,SF,and SS)was implemented for 23 coupling treatments over three growing seasons,including spring(2022S and 2023S)and autumn(2022A).The technique for order preference by similarity to ideal solution(TOPSIS)combining weights based on game theory was applied to construct cucumber comprehensive growth evaluation model.Single and two experimental factors analyses revealed significant effects of single factors and the coupling of NS-SS,NS-SF and SS-SF on the integrated growth of cucumber for all three growing seasons.For the NS-SF-SS combination,the optimal parameters for comprehensive cucumber growth were determined as follows:levels of^(-1).68 for NS,-0.7 for SF,and^(-1).682 for SS in 2022A;-0.43 for NS,-0.06 for SF,and 0.34 for SS in 2022S;0.3 for NS,-0.02 for SF,and 0.04 for SS in 2023S.Furthermore,for SS ranges of 2.00-3.01,3.01-4.50,4.50-5.99,5.99-7.00(L·plant^(-1)),the corresponding NS and SF intervals maximizing cucumber integrated growth in spring were:0.28-0.30(L·plant^(-1))and 6(times·d^(-1)),0.26-0.30(L·plant^(-1))and 6(times·d^(-1)),0.25-0.30(L·plant^(-1))and 6(times·d^(-1)),0.23-0.30(L·plant^(-1))and 6(times·d^(-1)),respectively.With the same SS,the corresponding NS and SF intervals that maximized cucumber integrated growth in autumn were:0.10(L·plant^(-1))and 8(times·d^(-1)),0.18(L·plant^(-1))and 7(times·d^(-1)),0.30(L·plant^(-1))and 6(times·d^(-1)),0.49(L·plant^(-1))and 5(times·d^(-1)),respectively.The results provide a theoretical basis for solution management,and further in-depth research on cucumber cultivation.展开更多
The high-temperature interaction of nanostructured Lu_(2)Si_(2)O_(7) environmental barrier coatings(EBCs)with calcium-magnesium-aluminosilicate(CMAS)was investigated at 1400℃ for 1,10,25,and 50 h to evaluate the coat...The high-temperature interaction of nanostructured Lu_(2)Si_(2)O_(7) environmental barrier coatings(EBCs)with calcium-magnesium-aluminosilicate(CMAS)was investigated at 1400℃ for 1,10,25,and 50 h to evaluate the coating’s resistance to CMAS corrosion.The results indicate a phase transformation over time,transitioning from Ca_(2)Lu_(8)(SiO_(4))6O_(2) apatite and Lu_(2)Si_(2)O_(7) to solely Lu_(2)Si_(2)O_(7).The interaction of the Lu_(2)Si_(2)O_(7) coating with the CMAS melts was divided into three stages based on the corrosion reaction behavior.The delamination cracks were distributed throughout the interface between the Si bond layer and Lu_(2)Si_(2)O_(7) layer after corroded at 1400℃ for 50 h,signifying coating failure.In addition,the influence of monosilicates,disilicates,and corrosion duration on the recession layer thickness was analyzed by comparing previous reports on RE_(2)SiO_(5)/RE_(2)Si_(2)O_(7) coatings(RE=Gd,Yb,Lu,Er).Furthermore,the variation in the thermally grown oxide layer thickness in CMAS-corroded Lu_(2)Si_(2)O_(7) coatings was systematically investigated.展开更多
Dual-layer thermal barrier coatings(TBCs)with ultrahigh temperature resistance were prepared on the surface of molybdenum-rhenium alloy hot-end components.The preparation of the MoSi_(2)-Gd_(2)Zr_(2)O_(7)dual-layer TB...Dual-layer thermal barrier coatings(TBCs)with ultrahigh temperature resistance were prepared on the surface of molybdenum-rhenium alloy hot-end components.The preparation of the MoSi_(2)-Gd_(2)Zr_(2)O_(7)dual-layer TBCs was designed based on the coefficient of thermal expansion and the coating functionality,and it was completed using atmospheric plasma spraying technique.The microstructure,mechanical properties,and thermal properties were analyzed.Results indicate that the adhesion of the prepared dual-layer composite TBCs is excellent,and no noticeable cracks appear at the interface.Compared with the MoSi_(2)coating with a low fracture toughness(0.88 MPa·m^(1/2)),the Gd_(2)Zr_(2)O_(7)coating exhibits higher fracture toughness(1.74 MPa·m^(1/2))and stronger resistance to crack propagation.The prepared MoSi_(2)-Gd_(2)Zr_(2)O_(7)composite coatings have a high porosity(39%),low thermal conductivity(1.020 W·(m·K)^(−1),1200℃),and low thermal diffusivity(0.249 mm^(2)/s,1200℃).Additionally,they possess a high oxygen-vacancy concentration,which ensures excellent insulation performance.展开更多
基金Project supported by the Natural Science Foundation of Shandong Province of China(No.ZR2024MA085)the Fundamental Research Funds for Central Universities of China(No.27RA2515008)。
文摘When micro/nano-scale gradient coatings are subject to large thermal gradients or high heat fluxes,the spatial size effect cannot be ignored.It is important to understand how the size effect influences the thermal fracture behavior of functionally graded coating/substrate structures.This study aims at analyzing the transient thermal fracture behavior of collinear interface cracks in functionally graded coating/substrate structures based on the nonlocal dual-phase-lag heat conduction model.By means of integral transform techniques,the mixed boundary problem is transformed into a set of singular integral equations,which are solved by the Chebyshev polynomials.The effects of the nonlocal parameter,coating thickness,crack spacing,and non-homogeneous parameters on the temperature and stress intensity factors(SIFs)are examined.The numerical results show that these parameters play an essential role in controlling the thermal fracture behavior of the structures,especially at micro/nano-scales.
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National Natural Science Foundation of China(52071274)Key Research and Development Projects of Shaanxi Province(2023-YBGY-442)Science and Technology Nova Project-Innovative Talent Promotion Program of Shaanxi Province(2020KJXX-062)。
文摘To mitigate the impact of interdiffusion reactions between the silicide slurry and Ta12W alloy substrate during vacuum sintering process on the oxidation resistance of the silicide coating,a micro-arc oxidation pretreatment was employed to construct a Ta_(2)O_(5)ceramic layer on the Ta12W alloy surface.Subsequently,a slurry spraying-vacuum sintering method was used to prepare a Si-Cr-Ti-Zr coating on the pretreated substrate.Comparative studies were conducted on the microstructure,phase composition,and isothermal oxidation resistance(at 1600℃)of the as-prepared coatings with and without the micro-arc oxidation ceramic layer.The results show that the Ta_(2)O_(5)layer prepared at 400 V is more continuous and has smaller pores than that prepared at 350 V.After microarc oxidation pretreatment,the Si-Cr-Ti-Zr coating on Ta12W alloy consists of three distinct layers:an upper layer dominated by Ti_(5)Si_(3),Ta_(5)Si_(3),and ZrSi;a middle layer dominated by TaSi_(2);a coating/substrate interfacial reaction layer dominated by Ta_(5)Si_(3).Both the Si-Cr-Ti-Zr coatings with and without the Ta_(2)O_(5)ceramic layer do not fail after isothermal oxidation at 1600℃for 5 h.Notably,the addition of the Ta2O5 ceramic layer reduces the high-temperature oxidation rate of the coating.
基金support from National Science Foundation of China(22438005)the Natural Science Foundation of Jiangsu Province(BE2022056-3)is gratefully acknowledged.
文摘Nanoporous polymers are extensively coated on various substrates to deliver optical,permselective,or other functions.However,it remains desired to fast produce uniform nanoporous polymer coatings on substrates with complex surfaces.Herein,by manipulating the interactions between block copolymers and selective solvents,we prepare repairable nanoporous polymers on arbitrary substrates.This is realized by an extremely simple sequential coating process:sequential coating of block copolymers and their swelling agents on substrate surfaces.The swelling agents are comprised of two solvents that swell the constituent blocks of the copolymers to different degrees,rapidly producing polymer coatings with uniform,interconnected,sub-50 nm pores.This sequential coating process is able to conformally build nanoporous polymers on nonplanar substrates with large lateral sizes and complex surface features,and also to in situ repair defects arising during usages.We further demonstrate that the nanoporous coatings show excellent antireflective and membrane separation performances.This sequential coating process is dictated by polymer–solvent interactions,and is expected to find applications in diverse fields for its simplicity,adaptability,and the capability to produce well-defined nanoporosities.
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the support by the National Natural Science Foundation of China(grant numbers 52273048 and 51973006)the Beijing Natural Science Foundation of China(grant number 2222052)the financial support of this work by BIOFIRESAFE(PID2020-117274RB-I00)funded by MINECO,Spain。
文摘Developing high-efficient flame-retardant coatings is crucial for fire safety polymer and battery fields.Traditional intumescent coatings and ceramifiable coatings struggle to provide immediate and prolonged protection simultaneously,which limits the applicability.To address this,an innovative bi-layered coating with organic/nano-inorganic additives is inspired by differential response behaviors,enabling relay response effect with both fast-acting and extended protection.Specifically,two layers function continuously in the form of a relay.With a mere 320 microns,the bi-layered coating withstands fire temperatures of up to 1400℃for at least 900 s.Consequently,the coating effective prevented burn through in aluminum plates and glass fabric-reinforced epoxy resin,which otherwise were burned through in 135 and 173 s,respectively.Meanwhile,the bi-layered coating suppressed the formation and decomposition of solid interface layer in lithium soft-package batteries,leading to prolonged electrochemical stability and fire safety.Additionally,the bi-layered coating with a fast response endows polyurethane foam with rapid self-extinguishing,preventing ignition even under exposure to strong fire of 1400℃.Shortly,our work offers new insights into the design and development of thin,high-performance,and multi-application flame-retardant coatings.
基金Project (51045004) supported by the National Natural Science Foundation of ChinaProject (2006AA03A219) supported by Hi-tech Research and Development Program of ChinaProject (YYYJ-0913) supported by Knowledge Innovation Project in Chinese Academy of Sciences
文摘Fe-based coating was produced on pure Ti substrate by the laser cladding technology. The composition and microstructure of the fabricated coating were analyzed by scanning electron microscopy （SEM）, X-ray diffraction （XRD） and transmission electron microscopy （TEM） technique. The tribological properties were tested through sliding against AISI52100 steel ball at different normal loads and sliding speeds. Besides, the morphologies of the worn surfaces and wear debris were analyzed by scanning electron microscopy （SEM） and three dimensional （3D） non-contact surface mapping. The results show that the prepared Fe-based coating has a high hardness of about 860 HV0.2 and exhibits an average wear rate of （0.70-2.32）×10-6 mm3/（N-m）, showing that the Fe-based coating can greatly improve the wear resistance of pure Ti substrate. The wear mechanism of the coating involves moderate adhesive and abrasive wear.
基金Projects(CKJB201205,QKJB201202,YJK201307)supported by the Nanjing Institute of Technology,China
文摘The outermost coating with single phase Ni2Al3 was obtained on copper surface by electrodepositing nickel followed by slurry pack aluminizing at 800 °C for 12 h. The oxidation resistance and microstructure of the coating oxidized in ambient air at 1000 °C for 25-250 h were investigated using SEM, X-ray diffraction and optical microscope methods. The results show that the copper with single phase Ni2Al3 coating possesses the best high temperature oxidation resistance, and the mass gain of the coating is 1/15 that of pure copper and 1/2 that of nickel coating, respectively. The specimen surface after being oxidized for 25 h still comprises Ni2Al3 phase. However, when the time of oxidizing treatment increases to 50 h, the Ni Al phase is formed. It is also found that the Ni2Al3 phase completely turns into Ni Al phase after oxidizing treatment for 100 h and above. The Ni Al coating shows excellent high temperature oxidation resistance when oxidation time is 250 h.
基金supported by National Basic Research Program of China(2012CB921504)Major Program of National Natural Science Foundation of China(51239005)+4 种基金National Natural Science Foundation of China(11404147,11174142)Natural Science Foundation of Jiangsu Province(BK20140519)China Postdoctoral Science Foundation(2015M571672)Research Fund for Advanced Talents of Jiangsu University(11JDG118)Training Project of Young Backbone Teachers of Jiangsu University
文摘The propagation characteristics of laser-generated like-Rayleigh waves in viscoelastic adhesive coating/substrate structures were studied.Considering the viscoelasticity of the coating and substrate,we have established the finite element models in frequency domain for the laser-generated like-Rayleigh waves in the epoxy coating/aluminum substrate,epoxy coating/brass substrate,and epoxy coating/foam substrate structures,respectively.In addition,we have investigated the waveform and propagation characteristics of the like-Rayleigh waves and studied the influences of the coating transparency,coating thickness,coating viscoelasticity,and substrate viscoelasticity on the propagation characteristics of the like-Rayleigh waves.Moreover,we have verified the results by the theoretical phase velocity and attenuation curves.The results show that the coating viscoelasticity induces the attenuation characteristics of the higher frequencies of the like-Rayleigh waves,but has little effect on the lower frequencies,and the substrate viscoelasticity has the influences on both the higher and lower frequencies of the like-Rayleigh waves,especially the lower frequencies.Furthermore,the mode and dispersive characteristics of the like-Rayleigh waves are closely related to the substrates.This study provides a useful theoretical basis for inverting mechanical parameters and evaluating the adhesive quality of the viscoelastic adhesive coating/substrate structures.
基金Project(2011B050400007)supported by the International Cooperation Program of Guangdong Province,China
文摘Ti/TiN/Zr/ZrN multilayer coatings were deposited on Cr_17Ni_2 steel substrates with different surface roughnesses by vacuum cathodic arc deposition method. Microstructure, micro-hardness, adhesion strength and cross-sectional morphology of the obtained multilayer coatings were investigated. The results show that the Vickers hardness of Ti/TiN/Zr/ZrN multilayer coating, with a film thickness of 11.37 μm, is 29.36 GPa. The erosion and salt spray resistance performance of Cr_17Ni_2 steel substrates can be evidently improved by Ti/TiN/Zr/ZrN multilayer coating. The surface roughness of Cr_17Ni_2 steel substrates plays an important role in determining the mechanical and erosion performances of Ti/TiN/Zr/ZrN multilayer coatings. Overall, a low value of the surface roughness of substrates corresponds to an improved performance of erosion and salt spray resistance of multilayer coatings. The optimized performance of Ti/TiN/Zr/ZrN multilayer coatings can be achieved provided that the surface roughness of Cr_17Ni_2 steel substrates is lower than 0.4μm.
文摘Black nickel coatings have emerged as a research hotspot in materials science due to their excellent performance and broad application prospects.In this study,nickel-based black coatings were fabricated on low-carbon steel substrates via photo-assisted electrodeposition.A systematic investigation was conducted on the effects of cerium ion concentration and nano-ceria(CeO_(2))particle content in the electrolyte on the coating properties,along with an analysis of the temporal evolution of coating’s corrosion resistance.When the cerium ion concentration in the electrolyte was 0.05 mol/L,the coating exhibited a uniform black appearance with a light absorption rate of 95%,an emissivity of 0.87,maximum impedance,and the lowest corrosion tendency,demonstrating optimal comprehensive performance.The coating prepared with a nano-ceria concentration of 6 g/L in the electrolyte exhibited an emissivity of 0.9,achieved a 5B adhesion grade(ASTM D3359-09),and demonstrated a one-order-of-magnitude reduction in corrosion current density compared to coatings fabricated without nano-ceria in the electrolyte.With prolonged storage time,the coating's impedance slightly increased,leading to improved corrosion resistance.
基金The National Natural Science Foundation of China(No.10962008,51061015)Specialized Research Fund for the Doctoral Program of Higher Education of China(No.20116401110002)
文摘This paper investigates the functionally graded coating bonded to an elastic strip with a crack under thermal- mechanical loading. Considering some new boundary conditions, it is assumed that the temperature drop across the crack surface is the result of the thermal conductivity index which controls heat conduction through the crack region. By the Fourier transforms, the thermal-elastic mixed boundary value problems are reduced to a system of singular integral equations which can be approximately solved by applying the Chebyshev polynomials. The numerical computation methods for the temperature, the displacement field and the thermal stress intensity factors （TSIFs） are presented. The normal temperature distributions （NTD） with different parameters along the crack surface are analyzed by numerical examples. The influence of the crack position and the thermal-elastic non- homogeneous parameters on the TSIFs of modes I and 11 at the crack tip is presented. Results show that the variation of the thickness of the graded coating has a significant effect on the temperature jump across the crack surfaces when keeping the thickness of the substrate constant, and the thickness of functionally graded material （FGM） coating has a significant effect on the crack in the substrate. The results can be expected to be used for the purpose of gaining better understanding of the thermal-mechanical behavior of graded coatings.
基金National Natural Science Foundation of China(52272075,52472053)Research Fund of Youth Innovation Promotion Association of CAS,China(2021190)Defense Industrial Technology Development Program(JCKY2021130B007)。
文摘Carbon fiber-reinforced carbon aerogel(C/CA)composites are one of the most promising candidates for applications requiring both thermal insulation and load bearing capabilities.The preparation of anti-oxidation coatings on C/CA to address its susceptibility to oxidation is a feasible approach to promote its application in oxidative environments.However,the currently reported coatings on C/CA mainly focus on improving the ablation performance and coating preparation process typically necessitating high-temperature heat treatment.This procedure can increase its thermal conductivity and reduce its thermal insulation ability.In this study,a series of ceramic-resin coatings were fabricated on C/CA through a simple slurry brushing-drying approach at room temperature.The effects of phenolic resin content on the coating structure,residual stress,thermal shock,and oxidation behaviors were investigated.Due to the adhesive properties and curing-induced shrinkage,the PR-7.5 coating(containing 7.5%(in mass)phenolic resin in the slurry)exhibits bonding strength close to fracture strength of the substrate and residual compressive stress of 0.853 GPa,which is beneficial for resisting thermal shock cracking.However,excessive resin content(PR-10.0 containing 10.0%(in mass)phenolic resin in the slurry)induces tensile stress due to uneven curing shrinkage,thereby leading to thermal shock cracking.Meanwhile,oxidation tests reveal significantly reduced weight losses for PR-7.5(17.46%at 800℃/100 min,8.15%at 1000℃/120 min,3.15%at 1200℃/120 min)versus uncoated C/CA’s 44.60%loss at 800℃/20 min.This work provides a brand-new and simple approach to improving the anti-oxidation performance of C/CA and expands its application in mild oxidative environments.
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supported by the National Key Research and Development Program of China (Nos. 2022YFB3605203 and 2022YFB3608100)the National Natural Science Foundation of China (Nos. 62321004, 62227817, and 62374001)。
文摘The absence of large-size gallium nitride(GaN) substrates with low dislocation density remains a primary bottleneck for advancing GaN-based devices. Here, we demonstrate the achievement of 8-inch freestanding GaN substrates grown by hydride vapor phase epitaxy. Critical to this achievement is the improvement in gas-flow uniformity, which ensures exceptional thickness homogeneity and enables the crack-free growth of GaN. After laser lift-off(LLO) separation, the freestanding GaN substrate exhibits superior crystal quality, evidenced by full width at half maximum values of 68 and 54 arcsec for X-ray diffraction rocking curves of(002) and(102) planes, alongside a low dislocation density of 1.6 × 10^(6) cm^(-2). This approach establishes a robust pathway for the production of large-size GaN substrates, which are essential for advancing next-generation power electronics and high-efficiency photonics.
文摘Sporadic or late-onset Alzheimer’s disease(LOAD)occurs in 1 of 10 people over 65 years of age and comprises 95%of all AD patients.Unlike early-onset AD,which is caused by defined single gene mutations,the mechanisms and events underlying risk for LOAD are not fully understood and no substantial disease-modifying interventions are currently available.Age is the most prominent risk factor for LOAD,and interacting age-related and LOAD-associated factors contribute to its pathogenesis.Among these factors are changes in bioenergetic cell functions,which metabolize substrates and produce energy stored in adenosine triphosphate.
基金financially supported by the National Science and Technology Major Project(No.2024ZD1404705)。
文摘An advanced AlCrSiN/AlCrN/CrN/Cr multilayer coating was developed via hybrid multiarc ion plating and high-power impulse magnetron sputtering.The multilayer design enhanced the substrate-coating compatibility,achieving a critical load of 87.8 N.Silicon doping induced nanocrystallization and amorphization,increasing the hardness to 26 GPa.At high temperatures,a nanoscale Cr-rich(Cr,Al)_(2)O_(3) layer was formed,effectively inhibiting oxygen diffusion.The coating underwent unique phase transformations,during which Cr_(2)N and amorphous Si3N4 were converted into dispersed SiCr_(3) nanoparticles,which stabilized Cr atoms and suppressed their outward diffusion.Ab initio molecular dynamics simulations revealed that Cr atoms exhibited higher chemical activity and oxygen-capture capability than Al atoms and Si atoms served as diffusion barriers by pinning onto the oxidized surface,considerably improving the oxidation resistance of the coating.
基金supported by the China Agriculture Research System(Grant No.CARS-23-D06)the Key Research and Development Program of Shaanxi Province(Grant Nos.2024NC2-GJHX-29 and 2024NC-ZDCYL-05-08)Shaanxi Agricultural Collaborative Innovation and Extension Alliance Project(Grant No.LMZD202202).
文摘Substrate and nutrient supply are essential for vegetable cultivation in greenhouse.The strategies for plant nutrient supply vary depending on the cultivation methods or substrate dosages employed.With the development of mechanization,wide-row spacing substrate cultivation became an optimize mode of the greenhouse cucumber cultivation,aligning with the trend of intelligent agriculture.To determine the optimal nutrient solution supply amount(NS)and supply frequency(SF)for promoting the integrated growth of cucumber under wide-row spacing substrate cultivation,we explored the effects of substrate supply amount(SS),NS,and SF on cucumber yield,quality,and element utilization efficiency.A five-level quadratic orthogonal rotation combination design with three experimental factors(NS,SF,and SS)was implemented for 23 coupling treatments over three growing seasons,including spring(2022S and 2023S)and autumn(2022A).The technique for order preference by similarity to ideal solution(TOPSIS)combining weights based on game theory was applied to construct cucumber comprehensive growth evaluation model.Single and two experimental factors analyses revealed significant effects of single factors and the coupling of NS-SS,NS-SF and SS-SF on the integrated growth of cucumber for all three growing seasons.For the NS-SF-SS combination,the optimal parameters for comprehensive cucumber growth were determined as follows:levels of^(-1).68 for NS,-0.7 for SF,and^(-1).682 for SS in 2022A;-0.43 for NS,-0.06 for SF,and 0.34 for SS in 2022S;0.3 for NS,-0.02 for SF,and 0.04 for SS in 2023S.Furthermore,for SS ranges of 2.00-3.01,3.01-4.50,4.50-5.99,5.99-7.00(L·plant^(-1)),the corresponding NS and SF intervals maximizing cucumber integrated growth in spring were:0.28-0.30(L·plant^(-1))and 6(times·d^(-1)),0.26-0.30(L·plant^(-1))and 6(times·d^(-1)),0.25-0.30(L·plant^(-1))and 6(times·d^(-1)),0.23-0.30(L·plant^(-1))and 6(times·d^(-1)),respectively.With the same SS,the corresponding NS and SF intervals that maximized cucumber integrated growth in autumn were:0.10(L·plant^(-1))and 8(times·d^(-1)),0.18(L·plant^(-1))and 7(times·d^(-1)),0.30(L·plant^(-1))and 6(times·d^(-1)),0.49(L·plant^(-1))and 5(times·d^(-1)),respectively.The results provide a theoretical basis for solution management,and further in-depth research on cucumber cultivation.
基金supported by the National Science and Technology Major Project of China(No.2017-VI-0020-0093).
文摘The high-temperature interaction of nanostructured Lu_(2)Si_(2)O_(7) environmental barrier coatings(EBCs)with calcium-magnesium-aluminosilicate(CMAS)was investigated at 1400℃ for 1,10,25,and 50 h to evaluate the coating’s resistance to CMAS corrosion.The results indicate a phase transformation over time,transitioning from Ca_(2)Lu_(8)(SiO_(4))6O_(2) apatite and Lu_(2)Si_(2)O_(7) to solely Lu_(2)Si_(2)O_(7).The interaction of the Lu_(2)Si_(2)O_(7) coating with the CMAS melts was divided into three stages based on the corrosion reaction behavior.The delamination cracks were distributed throughout the interface between the Si bond layer and Lu_(2)Si_(2)O_(7) layer after corroded at 1400℃ for 50 h,signifying coating failure.In addition,the influence of monosilicates,disilicates,and corrosion duration on the recession layer thickness was analyzed by comparing previous reports on RE_(2)SiO_(5)/RE_(2)Si_(2)O_(7) coatings(RE=Gd,Yb,Lu,Er).Furthermore,the variation in the thermally grown oxide layer thickness in CMAS-corroded Lu_(2)Si_(2)O_(7) coatings was systematically investigated.
基金Supported by Scientific and Technological Innovation of Shaanxi Provincial State-Owned Capital Operation Budget(2022-056)Institute's Self-Developed Technology Program(0801YK2317)+4 种基金Qin Chuangyuan Cites High-Level Innovation and Entrepreneurship Talent Program(QCYRCXM-2023-120)Qin Chuangyuan Industry Cluster Zone“Four Chains”Integration Program(2024CY-JJQ-46)National Natural Science Foundation of China(52071274)Key Research and Development Projects of Shaanxi Province(2023-YBGY-442)Science and Technology Nova Project-Innovative Talent Promotion Program of Shaanxi Province(2020KJXX-062)。
文摘Dual-layer thermal barrier coatings(TBCs)with ultrahigh temperature resistance were prepared on the surface of molybdenum-rhenium alloy hot-end components.The preparation of the MoSi_(2)-Gd_(2)Zr_(2)O_(7)dual-layer TBCs was designed based on the coefficient of thermal expansion and the coating functionality,and it was completed using atmospheric plasma spraying technique.The microstructure,mechanical properties,and thermal properties were analyzed.Results indicate that the adhesion of the prepared dual-layer composite TBCs is excellent,and no noticeable cracks appear at the interface.Compared with the MoSi_(2)coating with a low fracture toughness(0.88 MPa·m^(1/2)),the Gd_(2)Zr_(2)O_(7)coating exhibits higher fracture toughness(1.74 MPa·m^(1/2))and stronger resistance to crack propagation.The prepared MoSi_(2)-Gd_(2)Zr_(2)O_(7)composite coatings have a high porosity(39%),low thermal conductivity(1.020 W·(m·K)^(−1),1200℃),and low thermal diffusivity(0.249 mm^(2)/s,1200℃).Additionally,they possess a high oxygen-vacancy concentration,which ensures excellent insulation performance.
