Solid lubricating coatings play a crucial role in preventing friction and wear failure of the hot-end sliding components in aviation engines.In this study,VAlN/Ag multi-layer coatings with excellent interfacial matchi...Solid lubricating coatings play a crucial role in preventing friction and wear failure of the hot-end sliding components in aviation engines.In this study,VAlN/Ag multi-layer coatings with excellent interfacial matching were fabricated using a hybrid magnetron sputtering technique.The type and energy of discharge plasmas were analyzed to comprehend their effects on depositing coatings.The coatings exhibit self-adaptive lubrication properties during the designed consecutive friction with stepwise heating from 25℃to 650℃.The microstructure evolution during early friction facilitates sufficient tribo-chemical reaction at 650℃,leading to the formation of a distinctive"ball-on-rail"structure that significantly reduces friction coefficient.Based on the first-principles calculations,it was found that the bond energy of Ag-O is lower than that of V-O in both AgVO_(3)and Ag_(3)VO_(4),which promotes slipping along the(110)crystal plane and contributes to exceptional tribological properties.The fatigue wear failure mechanism of hard coatings under the thermal-force coupling effects has been elucidated,alongside an exploration of consecutive tribology mechanism at atomic scales over a wide temperature range.展开更多
A multi-layer coating for carbon-carbon composites with a Si-W outer layer,a SiC barrier layer and a SiC transition layer is prepared by the combination of siliconiza-tion, CVD and liquid reaction method. The effect o...A multi-layer coating for carbon-carbon composites with a Si-W outer layer,a SiC barrier layer and a SiC transition layer is prepared by the combination of siliconiza-tion, CVD and liquid reaction method. The effect of temperature on the oxidation protec-tion life from 1600 to 17OOC is investigated. The thickness of the oxide film on thecoating surface is measured through SEM and EMPA. A concept of critical oxide filmthickness and a critical oxidation protection time is put forward, and, based on it, the re-lation of the critical time with temperature is analyzed. The re8ults show that the relationof the critical oxidation protection time with temperature found by the experiments is fullyidentical with that calcu1ated based on the critical thickness- The physical significance andthe effect factors of the critical oxide film thickness are discussed.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
The key parameters that characterize the morphological quality of multi-layer and multi-pass metal laser deposited parts are the surface roughness and the error between the actual printing height and the theoretical m...The key parameters that characterize the morphological quality of multi-layer and multi-pass metal laser deposited parts are the surface roughness and the error between the actual printing height and the theoretical model height.The Taguchi method was employed to establish the correlations between process parameter combinations and multi-objective characterization of metal deposition morphology(height error and roughness).Results show that using the signal-to-noise ratio and grey relational analysis,the optimal parameter combination for multi-layer and multi-pass deposition is determined as follows:laser power of 800 W,powder feeding rate of 0.3 r/min,step distance of 1.6 mm,and scanning speed of 20 mm/s.Subsequently,a Genetic Bayesian-back propagation(GB-BP)network is constructed to predict multi-objective responses.Compared with the traditional back propagation network,the GB-back propagation network improves the prediction accuracy of height error and surface roughness by 43.14%and 71.43%,respectively.This network can accurately predict the multi-objective characterization of morphological quality of multi-layer and multi-pass metal deposited parts.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
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
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
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
TiB_(2)coatings can significantly enhance the high-temperature oxidation resistance of molybdenum,which would broaden the application range of molybdenum and alloys thereof.However,traditional methods for preparing Ti...TiB_(2)coatings can significantly enhance the high-temperature oxidation resistance of molybdenum,which would broaden the application range of molybdenum and alloys thereof.However,traditional methods for preparing TiB_(2)coatings have disadvantages such as high equipment costs,complicated processes,and highly toxic gas emissions.This paper proposes an environmentally friendly method,which requires inexpensive equipment and simple processing,for preparing TiB_(2)coating on molybdenum via electrophoretic deposition within Na3AlF6-based molten salts.The produced TiB_(2)layer had an approximate thickness of 60μm and exhibited high density,outstanding hardness(38.2 GPa)and robust adhesion strength(51 N).Additionally,high-temperature oxidation experiments revealed that,at900℃,the TiB_(2)coating provided effective protection to the molybdenum substrate against oxidation for 3 h.This result indicates that the TiB_(2)coating prepared on molybdenum using molten salt electrophoretic deposition possesses good high-temperature oxidation resistance.展开更多
Waterborne acrylic coatings are widely utilized due to their cost-effectiveness,high transparency,strong resistance to weather and chemicals,impressive mechanical properties,and excellent adhesion to various substrate...Waterborne acrylic coatings are widely utilized due to their cost-effectiveness,high transparency,strong resistance to weather and chemicals,impressive mechanical properties,and excellent adhesion to various substrates.In these coatings,a reactive emulsifier containing phosphate groups can be integrated into the molecular chain during polymerization,which enhances the coating's compactness and corrosion resistance.This work focuses on the synthesis of styrene-butyl acrylate(St-BA)latex and methyl methacrylate-butyl acrylate(MMA-BA)latex using the reactive phosphate emulsifier ANPEO_(10)-P_(1) through seed emulsion polymerization,achieving a conversion rate of approximately 99%and a solid content close to 50%.The resulting coatings from St-BA and MMA-BA latexes demonstrated long-term corrosion protection for carbon steel and aluminum alloy due to in-situ phosphatization,effectively preventing flash rust.Notably,the MMA-BA coating exhibited remarkable durability,enduring immersion for up to 1224 h(51 d)on Q 235 carbon steel before reaching the failure threshold(|Z|0.01 Hz£106Ω·cm^(2))on Q 235 carbon steel.On 5052 aluminum alloy,the St-BA coating maintained|Z|0.01 Hz>10^(8)Ω·cm^(2) for 480 h(20 d).Furthermore,the corrosion resistance of St-BA and MMA BA coatings on Q 235 steel sheet and 5052 aluminum alloy surpassed that of commercially available MMA-BA and St BA coatings after immersion in a 3.5 wt%NaCl aqueous solution.This work also delves into the anticorrosion mechanism of MMA-BA and St-BA coatings.展开更多
The Sn−2Al filler metal was utilized to bond W90 tungsten heavy alloys by the ultrasonic-assisted coating technology in atmospheric environment at 250℃.The effects of ultrasonic power and ultrasonic time on microstru...The Sn−2Al filler metal was utilized to bond W90 tungsten heavy alloys by the ultrasonic-assisted coating technology in atmospheric environment at 250℃.The effects of ultrasonic power and ultrasonic time on microstructure and interfacial strength of Sn−2Al/W90 interface were investigated.The ultrasound improved the wettability of Sn−2Al filler metal on W90 surface.As the ultrasonic power increased and ultrasonic time increased,the size of Al phase in seam decreased.The maximum value of Sn−2Al/W90 interfacial strength reached 30.1 MPa.Based on the acoustic pressure simulation and bubble dynamics,the intensity of cavitation effect was proportional to ultrasonic power.The generated high temperature and high pressure by cavitation effect reached 83799.6 K and 1.26×10^(14) Pa,respectively.展开更多
Hafnium carbide(HfC)serves as a critical ablation-resistant coating for C/C composites used on the wing leading edges of high-speed vehicles during atmospheric re-entry[1-3].Under the action of high-temperature,oxidiz...Hafnium carbide(HfC)serves as a critical ablation-resistant coating for C/C composites used on the wing leading edges of high-speed vehicles during atmospheric re-entry[1-3].Under the action of high-temperature,oxidizing gas flow,the HfC coating forms a high-melting-point heterogeneous oxide layer,significantly delaying oxidation of the underlying material and preserving the structural integrity of the C/C composites[4].展开更多
Polymer nanocomposite coatings(PNCCs)are unprecedented generation of coatings engineered for displaying inexpensive and brilliant functional surface coatings with eminent corrosion guard,mechanical resistance,antimicr...Polymer nanocomposite coatings(PNCCs)are unprecedented generation of coatings engineered for displaying inexpensive and brilliant functional surface coatings with eminent corrosion guard,mechanical resistance,antimicrobial,chemical durability,electrical insulation,and UV aging features.Due to their widely anticipation in petroleum,applications in building,conveyance,aerospace,electronics,automobiles and energy,these multi-functional coatings have a tremendous leverage in human life,all technological and scientific subjects.Numerous applications have been made for multilateral polymers like polyurethane(PU),epoxy(EP),polyaniline(PANI)conductive polymer,polypyrrole(PPy),and etc,on various metallic surfaces especially,carbon steel substrate owing to their excellent resistance properties.Practically,nanomaterials can possess potential in the all-interdisciplinary domains of materials science and engineering,chemical and physical sciences,biological and health sciences.As known,the designed polymer nanocomposite coating paradigm is fundamentally constituted from polymer or resin as a vehicle and inorganic nanofillers(nanoparticles and nanocomposites).Some commercialized and excessively employed nanocontainers in polymer nanocomposite coating formulations,like ZnO,TiO_(2),carbon nanotubes(CNTs),clay,SiO_(2),Al_(2)O_(3),graphene,GO,CeO_(2),ZrO_(2),FeTiO_(3),etc were discussed.The current review covered the chemistry and potential applications of the largest utilized multifunctional polymer nanocomposite coatings such as EP,PU and other considerable PNCCs.Lately,a titanic attention was made for epoxy nanocomposites because of their distinct physicochemical characteristics,which result from the combined qualities of the nanoparticles and polymer material unity.In addition,the author incorporated some of his scientific contributions in this area represented in construction of innovative functional polymer nanocomposites for a variety of uses with high economic,industrial impacts and future orientation.Furthermore,some newly published applications of polymer nanocomposite coatings were incorporated and discussed.展开更多
In order to improve the oxidation resistance of carbon/carbon （C/C） composites,a SiC/C-AlPO4 multi-layer coating was fabricated on the C/C composites by a simple and low-cost method.The internal SiC bonding layer wa...In order to improve the oxidation resistance of carbon/carbon （C/C） composites,a SiC/C-AlPO4 multi-layer coating was fabricated on the C/C composites by a simple and low-cost method.The internal SiC bonding layer was prepared by a two-step pack cementation process and the external C-AlPO4 coating was deposited by hydrothermal electrophoretic deposition process.Phase compositions and microstructures of the as-prepared multi-layer coating were characterized by X-ray diffraction （XRD）,scaning electron microspocy （SEM） and energy dispersive spectrometer （EDS）.Anti-oxidation properties,oxidation behavior and the failure behavior of the coated composites were investigated.The results indicate that the multi-layer coating exhibits obviously two-layer structure.The inner layer is composed of β-SiC,α-SiC phase with a scale of silicon phase.The outer layer is composed of cristobalite aluminum phosphate （C-AlPO4） crystallites.The SEM observation shows the good bonding between the inner and outer layers.The multi-layer coating displays an excellent oxidation resistance in air in the temperature range from 1573 to 1773 K,and the corresponding oxidation activation energy of the coated C/C composites is calculated to be 117.2 kJ/mol.The oxidation process is predominantly controlled by the diffusion of O2 through the C-AlPO 4 coating.The failure of the multi-layer coating results from the generation of the microholes that may be left by the escape of the oxidation gases.展开更多
A Mo-Si-C-N multi-layered anti-oxidation coating was in-situ fabricated by introducing nitrogen atmosphere during the fused sintering of Mo-Si slurry pre-layer on carbon/carbon composites. The phase composition and mi...A Mo-Si-C-N multi-layered anti-oxidation coating was in-situ fabricated by introducing nitrogen atmosphere during the fused sintering of Mo-Si slurry pre-layer on carbon/carbon composites. The phase composition and microstructure of the Mo-Si-C-N coating were characterized by X-ray diffractometry, optical microscopy, scanning electron microscopy with energy dispersive spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy. The Mo-Si-C-N coating exhibited a three-layered structure. Besides the MoSi2/Si main-layer and the SiC bonding-layer, a surface layer of about 10 μm in thickness was synthesized on the coating surface. The surface layer mainly consisted of SiC nanowires and contained some Si3N4 and Si phases. SiC nanowires of 10 to 200 nm in diameter presented a terrace and distortion structure. Transmission electron microscopy indicated that the SiC nanowires grew along the preferred 〈111〉 direction. During oxidation test, SiC nanowires transmuted into SiO2 glass, which can play an important role in improving the oxidation resistance of C/C composites.展开更多
This article deals with designing a broadband and high efficiency metal multi-layer dielectric grating （MMDG） used to compress and stretch an ultrashort laser pulse. The diffraction characteristics of the IVIMDG are...This article deals with designing a broadband and high efficiency metal multi-layer dielectric grating （MMDG） used to compress and stretch an ultrashort laser pulse. The diffraction characteristics of the IVIMDG are analysed by using the rigorous coupled-wave method. The multi-layer dielectric used as the reflective mirror is made up of non- quarter-wave coatings. Taking the diffraction efficiency of the -1 order as the value of merit function, the parameters such as groove depth, residual thickness, duty cycle, and reflective mirror are optimized to obtain broadband and high diffraction efficiency. The optimized MMDG shows an ultra-broadband working spectrum with the average efficiency exceeding 97% over 160 nm wavelength centred at 1053 nm and TE polarization. The optimized MMDG should be useful for chirped pulse amplification.展开更多
Pd-Ni coating shows good corrosion resistance in strong corrosion environments.However,in complex aggressiveenvironments,the performance of the coatings is limited and further improvement is necessary.The effects of t...Pd-Ni coating shows good corrosion resistance in strong corrosion environments.However,in complex aggressiveenvironments,the performance of the coatings is limited and further improvement is necessary.The effects of the applied platingcurrent density on the composition,structure and properties of Pd-Ni coatings were studied.By changing the current density in thesame bath,multi-layer Pd-Ni coatings were prepared on316L stainless steel.Scanning electronic microscopy,weight loss tests,adhesion strength,porosity and electrochemical methods were used to study the corrosion resistance of the films prepared bydifferent coating methods.Compared with the single layer Pd-Ni coating,the multi-layer coatings showed higher microhardness,lower internal stress,lower porosity and higher adhesive strength.The multi-layer Pd-Ni coating showed obviously better corrosionresistance in hot sulfuric acid solution containing Cl-.展开更多
The AR coatings for GaInP/GaAs tandem solar cell are simulated.Results show that,under the condition of the lack of suitable encapsulation, a very low energy loss could be reached on MgF2/ZnS system; in the case of gl...The AR coatings for GaInP/GaAs tandem solar cell are simulated.Results show that,under the condition of the lack of suitable encapsulation, a very low energy loss could be reached on MgF2/ZnS system; in the case of glass encapsulation,the Al2O3/ZrO2 and Al2O3/TiO2 systems are appropriate choice; for AlInP window layer,the thickness of 30 nm is suitable.展开更多
Transparent TiO2/TiN/TiO2 multi-layer solar control coatings were prepared on normal soda-lime-silica float glass substrate by using d.c. reactive magnetron sputtering at substrate temperature ranging from room temper...Transparent TiO2/TiN/TiO2 multi-layer solar control coatings were prepared on normal soda-lime-silica float glass substrate by using d.c. reactive magnetron sputtering at substrate temperature ranging from room temperature to 620℃ . The dependence of optical properties of the coatings and the coating composition, on the substrate temperature was studied. The results of the optical properties show that as the substrate temperature increases, a visible transmittance as high as 65% can be obtained. When the substrate temperature is higher than 370℃ , the infrared reflectance decreases. The results of X-ray photoelectron spectroscopy (XPS) show that when the substrate temperature is higher than 520℃ in oxygen atmosphere, the formation of thin surface over-layers (TiNxOy,) on top of the TiN films can be observed. When the substrate temperature is at 62℃ , the oxynitride become TiO2, which results in the optical degradation of TiN layer in infrared reflectance.展开更多
基金supported by the National Natural Science Foundation of China(No.52025014)Natural Science Foundation of Zhejiang Province(No.LQ23E010002)+1 种基金Natural Science Foundation of Ningbo(No.2023QL049)Major Special Project of Ningbo(No.2023Z022).
文摘Solid lubricating coatings play a crucial role in preventing friction and wear failure of the hot-end sliding components in aviation engines.In this study,VAlN/Ag multi-layer coatings with excellent interfacial matching were fabricated using a hybrid magnetron sputtering technique.The type and energy of discharge plasmas were analyzed to comprehend their effects on depositing coatings.The coatings exhibit self-adaptive lubrication properties during the designed consecutive friction with stepwise heating from 25℃to 650℃.The microstructure evolution during early friction facilitates sufficient tribo-chemical reaction at 650℃,leading to the formation of a distinctive"ball-on-rail"structure that significantly reduces friction coefficient.Based on the first-principles calculations,it was found that the bond energy of Ag-O is lower than that of V-O in both AgVO_(3)and Ag_(3)VO_(4),which promotes slipping along the(110)crystal plane and contributes to exceptional tribological properties.The fatigue wear failure mechanism of hard coatings under the thermal-force coupling effects has been elucidated,alongside an exploration of consecutive tribology mechanism at atomic scales over a wide temperature range.
文摘A multi-layer coating for carbon-carbon composites with a Si-W outer layer,a SiC barrier layer and a SiC transition layer is prepared by the combination of siliconiza-tion, CVD and liquid reaction method. The effect of temperature on the oxidation protec-tion life from 1600 to 17OOC is investigated. The thickness of the oxide film on thecoating surface is measured through SEM and EMPA. A concept of critical oxide filmthickness and a critical oxidation protection time is put forward, and, based on it, the re-lation of the critical time with temperature is analyzed. The re8ults show that the relationof the critical oxidation protection time with temperature found by the experiments is fullyidentical with that calcu1ated based on the critical thickness- The physical significance andthe effect factors of the critical oxide film thickness are discussed.
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National Natural Science Foundation of China(52175237)。
文摘The key parameters that characterize the morphological quality of multi-layer and multi-pass metal laser deposited parts are the surface roughness and the error between the actual printing height and the theoretical model height.The Taguchi method was employed to establish the correlations between process parameter combinations and multi-objective characterization of metal deposition morphology(height error and roughness).Results show that using the signal-to-noise ratio and grey relational analysis,the optimal parameter combination for multi-layer and multi-pass deposition is determined as follows:laser power of 800 W,powder feeding rate of 0.3 r/min,step distance of 1.6 mm,and scanning speed of 20 mm/s.Subsequently,a Genetic Bayesian-back propagation(GB-BP)network is constructed to predict multi-objective responses.Compared with the traditional back propagation network,the GB-back propagation network improves the prediction accuracy of height error and surface roughness by 43.14%and 71.43%,respectively.This network can accurately predict the multi-objective characterization of morphological quality of multi-layer and multi-pass metal deposited parts.
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.
文摘Platinum group metals have high melting points,strong corrosion resistance,stable chemical properties,and low oxygen permeability in high-temperature oxygen-containing environments.As thermal protective coating materials,they have gained essential applications in the aerospace field and have excellent prospects for application in frontier military fields,such as protecting hot-end components of hypersonic aircraft.This research reviewed the latest research progress of platinum group metal coatings with hightemperature oxidation resistance,including coating preparation techniques,oxidation failure,and alloying modification.The leading preparation techniques of current platinum group metal coatings were discussed,as well as the advantages and disadvantages of various existing preparation techniques.Besides,the intrinsic properties,failure forms,and failure mechanisms of coatings of single platinum group metal in high-temperature oxygen-containing environments were analyzed.On this basis,the necessity,main methods,and main achievements of alloying modification of platinum group metals were summarized.Finally,the future development of platinum group coatings with high-temperature oxidation resistance was discussed and prospected.
基金financially supported by the National 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 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.
基金supported by the Original Exploratory Program of the National Natural Science Foundation of China(No.52450012)。
文摘TiB_(2)coatings can significantly enhance the high-temperature oxidation resistance of molybdenum,which would broaden the application range of molybdenum and alloys thereof.However,traditional methods for preparing TiB_(2)coatings have disadvantages such as high equipment costs,complicated processes,and highly toxic gas emissions.This paper proposes an environmentally friendly method,which requires inexpensive equipment and simple processing,for preparing TiB_(2)coating on molybdenum via electrophoretic deposition within Na3AlF6-based molten salts.The produced TiB_(2)layer had an approximate thickness of 60μm and exhibited high density,outstanding hardness(38.2 GPa)and robust adhesion strength(51 N).Additionally,high-temperature oxidation experiments revealed that,at900℃,the TiB_(2)coating provided effective protection to the molybdenum substrate against oxidation for 3 h.This result indicates that the TiB_(2)coating prepared on molybdenum using molten salt electrophoretic deposition possesses good high-temperature oxidation resistance.
基金Project(52373065)supported by the National Natural Science Foundation of ChinaProject(2220004002898)supported by the Zhuhai Industry University Research Cooperation and Basic and Applied Research Projects,China。
文摘Waterborne acrylic coatings are widely utilized due to their cost-effectiveness,high transparency,strong resistance to weather and chemicals,impressive mechanical properties,and excellent adhesion to various substrates.In these coatings,a reactive emulsifier containing phosphate groups can be integrated into the molecular chain during polymerization,which enhances the coating's compactness and corrosion resistance.This work focuses on the synthesis of styrene-butyl acrylate(St-BA)latex and methyl methacrylate-butyl acrylate(MMA-BA)latex using the reactive phosphate emulsifier ANPEO_(10)-P_(1) through seed emulsion polymerization,achieving a conversion rate of approximately 99%and a solid content close to 50%.The resulting coatings from St-BA and MMA-BA latexes demonstrated long-term corrosion protection for carbon steel and aluminum alloy due to in-situ phosphatization,effectively preventing flash rust.Notably,the MMA-BA coating exhibited remarkable durability,enduring immersion for up to 1224 h(51 d)on Q 235 carbon steel before reaching the failure threshold(|Z|0.01 Hz£106Ω·cm^(2))on Q 235 carbon steel.On 5052 aluminum alloy,the St-BA coating maintained|Z|0.01 Hz>10^(8)Ω·cm^(2) for 480 h(20 d).Furthermore,the corrosion resistance of St-BA and MMA BA coatings on Q 235 steel sheet and 5052 aluminum alloy surpassed that of commercially available MMA-BA and St BA coatings after immersion in a 3.5 wt%NaCl aqueous solution.This work also delves into the anticorrosion mechanism of MMA-BA and St-BA coatings.
基金supported by the National Natural Science Foundation of China(Nos.52105330,52175307)the Natural Science Foundation of Shandong Province,China(No.ZR2023JQ021)。
文摘The Sn−2Al filler metal was utilized to bond W90 tungsten heavy alloys by the ultrasonic-assisted coating technology in atmospheric environment at 250℃.The effects of ultrasonic power and ultrasonic time on microstructure and interfacial strength of Sn−2Al/W90 interface were investigated.The ultrasound improved the wettability of Sn−2Al filler metal on W90 surface.As the ultrasonic power increased and ultrasonic time increased,the size of Al phase in seam decreased.The maximum value of Sn−2Al/W90 interfacial strength reached 30.1 MPa.Based on the acoustic pressure simulation and bubble dynamics,the intensity of cavitation effect was proportional to ultrasonic power.The generated high temperature and high pressure by cavitation effect reached 83799.6 K and 1.26×10^(14) Pa,respectively.
基金supported by the National Natural Science Foundation of China(Grant Nos.52302115,52231004)。
文摘Hafnium carbide(HfC)serves as a critical ablation-resistant coating for C/C composites used on the wing leading edges of high-speed vehicles during atmospheric re-entry[1-3].Under the action of high-temperature,oxidizing gas flow,the HfC coating forms a high-melting-point heterogeneous oxide layer,significantly delaying oxidation of the underlying material and preserving the structural integrity of the C/C composites[4].
文摘Polymer nanocomposite coatings(PNCCs)are unprecedented generation of coatings engineered for displaying inexpensive and brilliant functional surface coatings with eminent corrosion guard,mechanical resistance,antimicrobial,chemical durability,electrical insulation,and UV aging features.Due to their widely anticipation in petroleum,applications in building,conveyance,aerospace,electronics,automobiles and energy,these multi-functional coatings have a tremendous leverage in human life,all technological and scientific subjects.Numerous applications have been made for multilateral polymers like polyurethane(PU),epoxy(EP),polyaniline(PANI)conductive polymer,polypyrrole(PPy),and etc,on various metallic surfaces especially,carbon steel substrate owing to their excellent resistance properties.Practically,nanomaterials can possess potential in the all-interdisciplinary domains of materials science and engineering,chemical and physical sciences,biological and health sciences.As known,the designed polymer nanocomposite coating paradigm is fundamentally constituted from polymer or resin as a vehicle and inorganic nanofillers(nanoparticles and nanocomposites).Some commercialized and excessively employed nanocontainers in polymer nanocomposite coating formulations,like ZnO,TiO_(2),carbon nanotubes(CNTs),clay,SiO_(2),Al_(2)O_(3),graphene,GO,CeO_(2),ZrO_(2),FeTiO_(3),etc were discussed.The current review covered the chemistry and potential applications of the largest utilized multifunctional polymer nanocomposite coatings such as EP,PU and other considerable PNCCs.Lately,a titanic attention was made for epoxy nanocomposites because of their distinct physicochemical characteristics,which result from the combined qualities of the nanoparticles and polymer material unity.In addition,the author incorporated some of his scientific contributions in this area represented in construction of innovative functional polymer nanocomposites for a variety of uses with high economic,industrial impacts and future orientation.Furthermore,some newly published applications of polymer nanocomposite coatings were incorporated and discussed.
基金supported by the National Natural Science Foundation of China (Grant No. 50772063)the Foundation of New Century Excellent Talent in University of China (Grant No. NCET-06-0893)+1 种基金the Doctorate Research Foundation of Ministry of Education of China(Grant No. 20070708001)the Graduate Innovation Fund of SUST
文摘In order to improve the oxidation resistance of carbon/carbon （C/C） composites,a SiC/C-AlPO4 multi-layer coating was fabricated on the C/C composites by a simple and low-cost method.The internal SiC bonding layer was prepared by a two-step pack cementation process and the external C-AlPO4 coating was deposited by hydrothermal electrophoretic deposition process.Phase compositions and microstructures of the as-prepared multi-layer coating were characterized by X-ray diffraction （XRD）,scaning electron microspocy （SEM） and energy dispersive spectrometer （EDS）.Anti-oxidation properties,oxidation behavior and the failure behavior of the coated composites were investigated.The results indicate that the multi-layer coating exhibits obviously two-layer structure.The inner layer is composed of β-SiC,α-SiC phase with a scale of silicon phase.The outer layer is composed of cristobalite aluminum phosphate （C-AlPO4） crystallites.The SEM observation shows the good bonding between the inner and outer layers.The multi-layer coating displays an excellent oxidation resistance in air in the temperature range from 1573 to 1773 K,and the corresponding oxidation activation energy of the coated C/C composites is calculated to be 117.2 kJ/mol.The oxidation process is predominantly controlled by the diffusion of O2 through the C-AlPO 4 coating.The failure of the multi-layer coating results from the generation of the microholes that may be left by the escape of the oxidation gases.
基金supported by the Foundation of Heilongjiang Province (No. LC04C16)the Foundation of Aerospace Technology (No. HTJSZC-0506) the Post-Doctor Foundation of Heilongjiang Province, China
文摘A Mo-Si-C-N multi-layered anti-oxidation coating was in-situ fabricated by introducing nitrogen atmosphere during the fused sintering of Mo-Si slurry pre-layer on carbon/carbon composites. The phase composition and microstructure of the Mo-Si-C-N coating were characterized by X-ray diffractometry, optical microscopy, scanning electron microscopy with energy dispersive spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy. The Mo-Si-C-N coating exhibited a three-layered structure. Besides the MoSi2/Si main-layer and the SiC bonding-layer, a surface layer of about 10 μm in thickness was synthesized on the coating surface. The surface layer mainly consisted of SiC nanowires and contained some Si3N4 and Si phases. SiC nanowires of 10 to 200 nm in diameter presented a terrace and distortion structure. Transmission electron microscopy indicated that the SiC nanowires grew along the preferred 〈111〉 direction. During oxidation test, SiC nanowires transmuted into SiO2 glass, which can play an important role in improving the oxidation resistance of C/C composites.
基金Project supported by the Program of Qingdao Municipal Science and Technology Bureau, China (Grant No. 12-1-4-2-(15)-jch)the National Natural Science Foundation of China (Grant Nos. 11274188 and 10904080)the Taishan Scholars Program of Shandong Province, China
文摘This article deals with designing a broadband and high efficiency metal multi-layer dielectric grating （MMDG） used to compress and stretch an ultrashort laser pulse. The diffraction characteristics of the IVIMDG are analysed by using the rigorous coupled-wave method. The multi-layer dielectric used as the reflective mirror is made up of non- quarter-wave coatings. Taking the diffraction efficiency of the -1 order as the value of merit function, the parameters such as groove depth, residual thickness, duty cycle, and reflective mirror are optimized to obtain broadband and high diffraction efficiency. The optimized MMDG shows an ultra-broadband working spectrum with the average efficiency exceeding 97% over 160 nm wavelength centred at 1053 nm and TE polarization. The optimized MMDG should be useful for chirped pulse amplification.
文摘Pd-Ni coating shows good corrosion resistance in strong corrosion environments.However,in complex aggressiveenvironments,the performance of the coatings is limited and further improvement is necessary.The effects of the applied platingcurrent density on the composition,structure and properties of Pd-Ni coatings were studied.By changing the current density in thesame bath,multi-layer Pd-Ni coatings were prepared on316L stainless steel.Scanning electronic microscopy,weight loss tests,adhesion strength,porosity and electrochemical methods were used to study the corrosion resistance of the films prepared bydifferent coating methods.Compared with the single layer Pd-Ni coating,the multi-layer coatings showed higher microhardness,lower internal stress,lower porosity and higher adhesive strength.The multi-layer Pd-Ni coating showed obviously better corrosionresistance in hot sulfuric acid solution containing Cl-.
文摘The AR coatings for GaInP/GaAs tandem solar cell are simulated.Results show that,under the condition of the lack of suitable encapsulation, a very low energy loss could be reached on MgF2/ZnS system; in the case of glass encapsulation,the Al2O3/ZrO2 and Al2O3/TiO2 systems are appropriate choice; for AlInP window layer,the thickness of 30 nm is suitable.
基金Funded by Key Natural Science Foundation of China Minis-try of Education and Natural Science Foundation for Key Teacher (No.99087).
文摘Transparent TiO2/TiN/TiO2 multi-layer solar control coatings were prepared on normal soda-lime-silica float glass substrate by using d.c. reactive magnetron sputtering at substrate temperature ranging from room temperature to 620℃ . The dependence of optical properties of the coatings and the coating composition, on the substrate temperature was studied. The results of the optical properties show that as the substrate temperature increases, a visible transmittance as high as 65% can be obtained. When the substrate temperature is higher than 370℃ , the infrared reflectance decreases. The results of X-ray photoelectron spectroscopy (XPS) show that when the substrate temperature is higher than 520℃ in oxygen atmosphere, the formation of thin surface over-layers (TiNxOy,) on top of the TiN films can be observed. When the substrate temperature is at 62℃ , the oxynitride become TiO2, which results in the optical degradation of TiN layer in infrared reflectance.
