The evolution of mechanical properties,localized corrosion resistance of a high purity Al-Zn-Mg-Cu alloy during non-isothermal aging(NIA)was investigated by hardness test,electrical conductivity test,tensile test,inte...The evolution of mechanical properties,localized corrosion resistance of a high purity Al-Zn-Mg-Cu alloy during non-isothermal aging(NIA)was investigated by hardness test,electrical conductivity test,tensile test,intergranular corrosion test,exfoliation corrosion test,slow strain rate tensile test and electrochemical test,and the mechanism has been discussed based on microstructure examination by optical microscopy,electron back scattered diffraction,scanning electron microscopy and scanning transmission electron microscopy.The NIA treatment includes a heating stage from 40℃to 180℃with a rate of 20℃/h and a cooling stage from 180℃to 40℃with a rate of 10℃/h.The results show that the hardness and strength increase rapidly during the heating stage of NIA since the increasing temperature favors the nucleation and the growth of strengthening precipitates and promotes the transformation of Guinier-Preston(GPI)zones toη'phase.During the cooling stage,the sizes ofη'phase increase with a little change in the number density,leading to a further slight increase of the hardness and strength.As NIA proceeds,the corroded morphology in the alloy changes from a layering feature to a wavy feature,the maximum corrosion depth decreases,and the reason has been analyzed based on the microstructural and microchemical feature of precipitates at grain boundaries and subgrain boundaries.展开更多
Forming a stable anti-corrosion surface layer on magnesium(Mg)and its alloys has become a major challenge in developing a desirable degradable medical implant in bone.In this study,a porous MgO layer was first formed ...Forming a stable anti-corrosion surface layer on magnesium(Mg)and its alloys has become a major challenge in developing a desirable degradable medical implant in bone.In this study,a porous MgO layer was first formed on Mg by plasma electrolytic oxidation(PEO),and then a Mg-Al layered double hydroxide(LDH)layer was prepared to seal the porous structure of the PEO layer(LDH-2h and LDH-12h)via hydrothermal treatment.The bilayer structure composite coating,which can effectively resist the penetration of surrounding media,is similar to plain Chinese tiles.The in vitro results revealed that compared with other coatings,the LDH-12h composite coating can reduce the release of Mg ions and induce a milder change in pH when immersed in phosphate-buffered saline(PBS).In vitro rat bone marrow stem cell(rBMSC)culture suggested that the LDH-12h composite coating is favorable for cell activity,proliferation and could improve the osteogenic activity of rBMSCs.A subcutaneous implantation test revealed that the as-prepared sample showed enhanced corrosion resistance and histocompatibility in vivo,especially in the LDH-12h group.Moreover,LDH-12h had the lowest rate of degradation and the closest combination with the new bone after being inserted into a rat femur for 12 weeks with no major organ dysfunction.In summary,the asprepared PEO/Mg-Al LDH composite coating is able to improve the corrosion resistance and biocompatibility of Mg and to enhance osteogenic activity in vivo,suggesting its promising prospects for orthopedic applications.展开更多
For the health monitoring of the offshore drilling platform in the salt-fog environment, three nonmetallic materials, i.e., silica, FR-4 epoxy board and sheet molding compound （SMC）, with the good anti-corrosion abi...For the health monitoring of the offshore drilling platform in the salt-fog environment, three nonmetallic materials, i.e., silica, FR-4 epoxy board and sheet molding compound （SMC）, with the good anti-corrosion ability were chosen as the packaging materials for the fiber Bragg grating （FBG） strain sensors. By selecting a highly sensitive structure of the fiber Bragg grating strain sensor, the performances of the sensors with three materials were investigated both numerically and experimentally. The strain sensitivities were 3.76pm/με, 3.02pm/με and 3.03pm/με, respectively. The linearity was better than 0.998. It provides useful information for developing sensors for the marine engineering.展开更多
基金Project(202302AB080024)supported by the Department of Science and Technology of Yunnan Province,China。
文摘The evolution of mechanical properties,localized corrosion resistance of a high purity Al-Zn-Mg-Cu alloy during non-isothermal aging(NIA)was investigated by hardness test,electrical conductivity test,tensile test,intergranular corrosion test,exfoliation corrosion test,slow strain rate tensile test and electrochemical test,and the mechanism has been discussed based on microstructure examination by optical microscopy,electron back scattered diffraction,scanning electron microscopy and scanning transmission electron microscopy.The NIA treatment includes a heating stage from 40℃to 180℃with a rate of 20℃/h and a cooling stage from 180℃to 40℃with a rate of 10℃/h.The results show that the hardness and strength increase rapidly during the heating stage of NIA since the increasing temperature favors the nucleation and the growth of strengthening precipitates and promotes the transformation of Guinier-Preston(GPI)zones toη'phase.During the cooling stage,the sizes ofη'phase increase with a little change in the number density,leading to a further slight increase of the hardness and strength.As NIA proceeds,the corroded morphology in the alloy changes from a layering feature to a wavy feature,the maximum corrosion depth decreases,and the reason has been analyzed based on the microstructural and microchemical feature of precipitates at grain boundaries and subgrain boundaries.
基金the National Natural Science Foundation of China(81901048,81921002,81620108006 and 31771044)Shanghai Committee of Science and Technology,China(18410760600)the International Partnership Program of Chinese Academy of Sciences(GJHZ1850)。
文摘Forming a stable anti-corrosion surface layer on magnesium(Mg)and its alloys has become a major challenge in developing a desirable degradable medical implant in bone.In this study,a porous MgO layer was first formed on Mg by plasma electrolytic oxidation(PEO),and then a Mg-Al layered double hydroxide(LDH)layer was prepared to seal the porous structure of the PEO layer(LDH-2h and LDH-12h)via hydrothermal treatment.The bilayer structure composite coating,which can effectively resist the penetration of surrounding media,is similar to plain Chinese tiles.The in vitro results revealed that compared with other coatings,the LDH-12h composite coating can reduce the release of Mg ions and induce a milder change in pH when immersed in phosphate-buffered saline(PBS).In vitro rat bone marrow stem cell(rBMSC)culture suggested that the LDH-12h composite coating is favorable for cell activity,proliferation and could improve the osteogenic activity of rBMSCs.A subcutaneous implantation test revealed that the as-prepared sample showed enhanced corrosion resistance and histocompatibility in vivo,especially in the LDH-12h group.Moreover,LDH-12h had the lowest rate of degradation and the closest combination with the new bone after being inserted into a rat femur for 12 weeks with no major organ dysfunction.In summary,the asprepared PEO/Mg-Al LDH composite coating is able to improve the corrosion resistance and biocompatibility of Mg and to enhance osteogenic activity in vivo,suggesting its promising prospects for orthopedic applications.
文摘For the health monitoring of the offshore drilling platform in the salt-fog environment, three nonmetallic materials, i.e., silica, FR-4 epoxy board and sheet molding compound （SMC）, with the good anti-corrosion ability were chosen as the packaging materials for the fiber Bragg grating （FBG） strain sensors. By selecting a highly sensitive structure of the fiber Bragg grating strain sensor, the performances of the sensors with three materials were investigated both numerically and experimentally. The strain sensitivities were 3.76pm/με, 3.02pm/με and 3.03pm/με, respectively. The linearity was better than 0.998. It provides useful information for developing sensors for the marine engineering.
