Due to the excellent corrosion resistance and high irradiation damage resistance,Ti 2AlC MAX phase is considered as a candidate for applications as corrosion resistant and irradiation resistant protective coating.MAX ...Due to the excellent corrosion resistance and high irradiation damage resistance,Ti 2AlC MAX phase is considered as a candidate for applications as corrosion resistant and irradiation resistant protective coating.MAX phase coatings can be fabricated through firstly depositing a coating containing the three elements M,A,and X close to stoichiometry of the MAX phases using physical vapor deposition,followed by heat treatment in vacuum.In this work,Ti-Al-C coating was prepared on austenitic stainless steels by reactive DC magnetron sputtering with a compound Ti （50）Al （50） target,and CH4 used as the reactive gas.It was found that the as-deposited coating is mainly composed of Ti 3AlC antiperovskite phase with supersaturated solid solution of Al.Additionally,the ratio of Ti/Al remained the same as that of the target composition.Nevertheless,a thicker thermally grown Ti 2AlC MAX phase coating was obtained after being annealed at 800℃ in vacuum for 1 h.Meanwhile,the ratio of Ti/Al became close to stoichiometry of Ti 2AlC MAX phases.It can be understood that owing to the higher activity of Al,it diffused quickly into the substrate during annealing,and then more stable Ti 2AlC MAX phases transformed from the Ti 3AlC antiperovskite phase.展开更多
To investigate the influences of Cr2AlC mass fraction and supersonic plasma spraying process on the microstructure and mechanical properties of Cr2AlC reinforced 410 stainless steel composite coatings,the coatings con...To investigate the influences of Cr2AlC mass fraction and supersonic plasma spraying process on the microstructure and mechanical properties of Cr2AlC reinforced 410 stainless steel composite coatings,the coatings containing different mass fractions of Cr2AlC were prepared and investigated.The composite coating exhibited low porosity and high adhesion strength.The addition of Cr2AlC significantly enhanced the hardness of the composite coatings through particle strengthening.However,when the mass fraction of Cr2AlC was 20%,the aggregation of Cr2AlC resulted in a strong decrease in the coating preparation efficiency,as well as a decline in adhesion strength.In the supersonic plasma spraying process,the Ar flow rate mainly influenced the flight velocity of the particles,while the H2 flow rate and the current mainly affected the temperature of the plasma torch.Consequently,all of them influenced the melting degree of particles and the quality of the coating.The lowest porosity and the highest hardness and adhesion strength could be obtained when the Ar flow rate is 125 L/min,the H2 flow rate is 25 L/min,and the current is 385 A.展开更多
The interesting hybrid properties of ceramics and metals induced by unique nano-laminated structures make the M_(n+1)AX n(MAX)phase attractive as a potential protective coating for vital structural compo-nents in hars...The interesting hybrid properties of ceramics and metals induced by unique nano-laminated structures make the M_(n+1)AX n(MAX)phase attractive as a potential protective coating for vital structural compo-nents in harsh systems.However,an extremely narrow phase-forming region makes it difficult to prepare MAX phase coatings with high purity,which is required to obtain coatings with high-temperature anti-oxidation capabilities.This work describes the dependence of the phase evolution in deposited M-Al-C(M=Ti,V,Cr)coatings as a function on temperature using in-situ X-ray diffraction analysis.Compared to V_(2)AlC and Cr_(2)AlC MAX phase coatings,the Ti_(2)AlC coating displayed a higher phase-forming tempera-ture accompanied by a lack of any intermediate phases before the appearance of the Ti_(2)AlC MAX phase.The results of the first-principle calculations correlated with the experience in which Ti_(2)AlC exhibited the largest formation energy and density of states.The effect of the phase compositions of these three MAX phase coatings on mechanical properties were also investigated using ex-situ Vickers and nano-indenter tests,demonstrating the improved mechanical properties with good stability at high temperatures.These findings provide a deeper understanding of the phase-forming mechanism of MAX phase coatings to guide the preparation of high-purity MAX phase coatings and the optimization of MAX phase coatings with expected intermediate phases such as Cr_(2)C,V_(2)C etc.,as well as their application as protective coat-ings in temperature-related harsh environments.展开更多
In order to enhance the ablation-resistant performance of stainless-steel conductive rails,Mo coating,410 stainless steel coating and 15 wt%Cr_(2)AlIC particles reinforced 410 stainless steel composite coating were pr...In order to enhance the ablation-resistant performance of stainless-steel conductive rails,Mo coating,410 stainless steel coating and 15 wt%Cr_(2)AlIC particles reinforced 410 stainless steel composite coating were prepared and evaluated.Different from the weak interfacial strength caused by the dissimilar metals between Mo and steel rails,410 stainless steel coating has better interfacial contact with steel rails.The introduction of Cr_(2)AlC into 410 stainless steels further strengthened the mechanical properties of coating by alloy strengthening effect and particle strengthening effect,as the decomposition of Cr_(2)AlC into nano CrC particles is accompanied with the diffusion of Al atoms into 410 stainless steels.It was found that the composite coating can still resist arc erosion at 150 A current,as a dense oxide film formed during the ablation process and the decomposition of Cr_(2)AlC contributed to the heat absorption.展开更多
基金supported by the National Natural Science Foundation of China (Grant No.51522106 and Grant No.51401229)the National Science and Technology Major Project of China (Grant No.2015ZX06004-001)the Ningbo Municipal Natural Science Foundation (Grant No.2014A610013)
文摘Due to the excellent corrosion resistance and high irradiation damage resistance,Ti 2AlC MAX phase is considered as a candidate for applications as corrosion resistant and irradiation resistant protective coating.MAX phase coatings can be fabricated through firstly depositing a coating containing the three elements M,A,and X close to stoichiometry of the MAX phases using physical vapor deposition,followed by heat treatment in vacuum.In this work,Ti-Al-C coating was prepared on austenitic stainless steels by reactive DC magnetron sputtering with a compound Ti （50）Al （50） target,and CH4 used as the reactive gas.It was found that the as-deposited coating is mainly composed of Ti 3AlC antiperovskite phase with supersaturated solid solution of Al.Additionally,the ratio of Ti/Al remained the same as that of the target composition.Nevertheless,a thicker thermally grown Ti 2AlC MAX phase coating was obtained after being annealed at 800℃ in vacuum for 1 h.Meanwhile,the ratio of Ti/Al became close to stoichiometry of Ti 2AlC MAX phases.It can be understood that owing to the higher activity of Al,it diffused quickly into the substrate during annealing,and then more stable Ti 2AlC MAX phases transformed from the Ti 3AlC antiperovskite phase.
基金supported by the Beijing Natural Science Foundation(Grant No.3232011)the Joint Fund of the Ministry of Education for Equipment Pre-research(Grant No.8091B02022306)the National Natural Science Foundation of China(Grant No.52175284).
文摘To investigate the influences of Cr2AlC mass fraction and supersonic plasma spraying process on the microstructure and mechanical properties of Cr2AlC reinforced 410 stainless steel composite coatings,the coatings containing different mass fractions of Cr2AlC were prepared and investigated.The composite coating exhibited low porosity and high adhesion strength.The addition of Cr2AlC significantly enhanced the hardness of the composite coatings through particle strengthening.However,when the mass fraction of Cr2AlC was 20%,the aggregation of Cr2AlC resulted in a strong decrease in the coating preparation efficiency,as well as a decline in adhesion strength.In the supersonic plasma spraying process,the Ar flow rate mainly influenced the flight velocity of the particles,while the H2 flow rate and the current mainly affected the temperature of the plasma torch.Consequently,all of them influenced the melting degree of particles and the quality of the coating.The lowest porosity and the highest hardness and adhesion strength could be obtained when the Ar flow rate is 125 L/min,the H2 flow rate is 25 L/min,and the current is 385 A.
基金financially supported by the National Natural Science Foundation of China (Nos.52025014,52171090,52101109,U22A20111).
文摘The interesting hybrid properties of ceramics and metals induced by unique nano-laminated structures make the M_(n+1)AX n(MAX)phase attractive as a potential protective coating for vital structural compo-nents in harsh systems.However,an extremely narrow phase-forming region makes it difficult to prepare MAX phase coatings with high purity,which is required to obtain coatings with high-temperature anti-oxidation capabilities.This work describes the dependence of the phase evolution in deposited M-Al-C(M=Ti,V,Cr)coatings as a function on temperature using in-situ X-ray diffraction analysis.Compared to V_(2)AlC and Cr_(2)AlC MAX phase coatings,the Ti_(2)AlC coating displayed a higher phase-forming tempera-ture accompanied by a lack of any intermediate phases before the appearance of the Ti_(2)AlC MAX phase.The results of the first-principle calculations correlated with the experience in which Ti_(2)AlC exhibited the largest formation energy and density of states.The effect of the phase compositions of these three MAX phase coatings on mechanical properties were also investigated using ex-situ Vickers and nano-indenter tests,demonstrating the improved mechanical properties with good stability at high temperatures.These findings provide a deeper understanding of the phase-forming mechanism of MAX phase coatings to guide the preparation of high-purity MAX phase coatings and the optimization of MAX phase coatings with expected intermediate phases such as Cr_(2)C,V_(2)C etc.,as well as their application as protective coat-ings in temperature-related harsh environments.
基金supported by Beijing Natural Science Foundation(3232011)the Pre-Research Program in National 14th Five-Year Plan(80923010304)the National Natural Science Foundation of China(52130509).
文摘In order to enhance the ablation-resistant performance of stainless-steel conductive rails,Mo coating,410 stainless steel coating and 15 wt%Cr_(2)AlIC particles reinforced 410 stainless steel composite coating were prepared and evaluated.Different from the weak interfacial strength caused by the dissimilar metals between Mo and steel rails,410 stainless steel coating has better interfacial contact with steel rails.The introduction of Cr_(2)AlC into 410 stainless steels further strengthened the mechanical properties of coating by alloy strengthening effect and particle strengthening effect,as the decomposition of Cr_(2)AlC into nano CrC particles is accompanied with the diffusion of Al atoms into 410 stainless steels.It was found that the composite coating can still resist arc erosion at 150 A current,as a dense oxide film formed during the ablation process and the decomposition of Cr_(2)AlC contributed to the heat absorption.
