Ni-P/SiC/PTFE coating was obtained on the surface of 316L stainless steel by electrodeposition of Ni-P/SiC coating and immersion of PTFE(polytetrafluoroethylene).The surface morphology and composition were analyzed by...Ni-P/SiC/PTFE coating was obtained on the surface of 316L stainless steel by electrodeposition of Ni-P/SiC coating and immersion of PTFE(polytetrafluoroethylene).The surface morphology and composition were analyzed by scanning electron microscope and energy dispersive spectrometer.The corrosion resistance of the coating in 0.5 mol/L H2SO4+2×10−6 HF solution was studied by electrochemical method.Surface contact angle was used to test the hydrophobic properties of the coating.The results indicated that the Ni-P/SiC/PTFE coating prepared on the surface of stainless steel was uniform and compact,which significantly improved the self-corrosion potential of stainless steel.The self-corrosion current density decreased from 7.62 to 0.008μA/cm2.The durability performance of coating was tested under 0.6 V voltage and the stable corrosion current density value was 0.19μA/cm2,then wetting angle was tested after durability experiment and the value is 134.5°.展开更多
Non-isothermal aging(NIA)treatments have presented significant advantages in improving the comprehensive performance and aging hardening efficiency of the 7000 series aluminum alloys,but there is no attention paid to ...Non-isothermal aging(NIA)treatments have presented significant advantages in improving the comprehensive performance and aging hardening efficiency of the 7000 series aluminum alloys,but there is no attention paid to their composites.This study takes a linear heating aging process as an example to reveal the precipitation behaviors of a 15 vol.%SiC/7085Al composite as well as its impact on mechanical properties using differential scanning calorimetry,transmission electron microscopy,small-angle neutron scattering,hardness measurements,and tensile testing.The results indicated the formation of GP(Ⅰ,Ⅱ)zones,η’andηprecipitates in sequence,leading to the hardness and strength initially increasing and then decreasing with rising NIA temperatures.The maximums were reached at 183℃,corresponding to the appearance ofη’precipitates in large quantities.Owing to the rapid temperature rise during the NIA process,the precipitates entered the coarsening and redissolution stage before they were entirely formed,resulting in reduced peak strength compared to the T6 treatment.The composite exhibited a more significant reduction in strength than the 7085Al alloy because:(i)the annihilation of vacancies suppressed the formation of GPII zones,thereby weakening their transition toη’precipitates;(ii)quenching dislocations promoted the coarsening of precipitates.An improved NIA process,incorporating both heating and cooling aging treatments,was effectively designed with the assistance of in-situ SANS technology to address this issue,which allows for achieving strength comparable to that after the T6 treatment with only 15%of the aging time consumption.This research fills the gap in investigating the NIA precipitation behaviors of aluminum matrix composites,providing guidance for the formulation of NIA schedules.展开更多
基金Project(2018YFB1502500)supported by the National Key Research and Development Program of ChinaProject supported by State Key Laboratory of Powder Metallurgy,Central South University,China+1 种基金Projects(2020JJ5100,2018JJ3101)supported by Natural Science Foundation of Hunan Province,ChinaProject(51671085)supported by the National Natural Science Foundation of China。
文摘Ni-P/SiC/PTFE coating was obtained on the surface of 316L stainless steel by electrodeposition of Ni-P/SiC coating and immersion of PTFE(polytetrafluoroethylene).The surface morphology and composition were analyzed by scanning electron microscope and energy dispersive spectrometer.The corrosion resistance of the coating in 0.5 mol/L H2SO4+2×10−6 HF solution was studied by electrochemical method.Surface contact angle was used to test the hydrophobic properties of the coating.The results indicated that the Ni-P/SiC/PTFE coating prepared on the surface of stainless steel was uniform and compact,which significantly improved the self-corrosion potential of stainless steel.The self-corrosion current density decreased from 7.62 to 0.008μA/cm2.The durability performance of coating was tested under 0.6 V voltage and the stable corrosion current density value was 0.19μA/cm2,then wetting angle was tested after durability experiment and the value is 134.5°.
基金support of the Na-tional Key R&D Program of China(No.2021YFA1600700)the Na-tional Natural Science Foundation of China(grant Nos.U22A20114,52322106,52192595,and 52301200)+2 种基金the Project funded by China Postdoctoral Science Foundation(No.2023M733573)CSNS Con-sortium on High-performance Materials of Chinese Academy of Sciences(No.JZHKYPT-2021-01)the Natural Science Foun-dation of Liaoning Province(No.2023-BS-020)。
文摘Non-isothermal aging(NIA)treatments have presented significant advantages in improving the comprehensive performance and aging hardening efficiency of the 7000 series aluminum alloys,but there is no attention paid to their composites.This study takes a linear heating aging process as an example to reveal the precipitation behaviors of a 15 vol.%SiC/7085Al composite as well as its impact on mechanical properties using differential scanning calorimetry,transmission electron microscopy,small-angle neutron scattering,hardness measurements,and tensile testing.The results indicated the formation of GP(Ⅰ,Ⅱ)zones,η’andηprecipitates in sequence,leading to the hardness and strength initially increasing and then decreasing with rising NIA temperatures.The maximums were reached at 183℃,corresponding to the appearance ofη’precipitates in large quantities.Owing to the rapid temperature rise during the NIA process,the precipitates entered the coarsening and redissolution stage before they were entirely formed,resulting in reduced peak strength compared to the T6 treatment.The composite exhibited a more significant reduction in strength than the 7085Al alloy because:(i)the annihilation of vacancies suppressed the formation of GPII zones,thereby weakening their transition toη’precipitates;(ii)quenching dislocations promoted the coarsening of precipitates.An improved NIA process,incorporating both heating and cooling aging treatments,was effectively designed with the assistance of in-situ SANS technology to address this issue,which allows for achieving strength comparable to that after the T6 treatment with only 15%of the aging time consumption.This research fills the gap in investigating the NIA precipitation behaviors of aluminum matrix composites,providing guidance for the formulation of NIA schedules.
