As a classic in-situ reaction, the Al-TiO_(2) reaction is expected to prepare aluminum matrix composites with high thermal stability.In this study, it was found that the preparation method of ensuring sufficient react...As a classic in-situ reaction, the Al-TiO_(2) reaction is expected to prepare aluminum matrix composites with high thermal stability.In this study, it was found that the preparation method of ensuring sufficient reaction using higher temperatures in previous studies was not conducive to acquiring optimized high-temperature strength. With the increase of hot-pressing temperature and the extension of holding time, the in-situ reaction became more thorough, but the strength of the composites first increased and then decreased. Coarsening of the microstructure at high temperatures would lead to degradation of strength and controlling the in-situ reaction process by the hot-pressing parameters could optimize the mechanical properties of the composites. Strengthening mechanisms at room and high temperatures were studied, and it was found that the load-transfer and Orowan strengthening mechanisms are the main strengthening effects at room temperature, while the pinning effect of fine particles became more crucial at elevated temperatures. As a result, the coarsening of the reinforcing phases was more detrimental to the hightemperature strength. Therefore, an insufficient in-situ reaction led to more excellent mechanical properties, and the composite hot-pressed at 605℃ and held for 2 h exhibited the highest strength, which was 367 MPa at room temperature and 170 MPa at 350℃.展开更多
Metallic glasses have recently attracted great attention in terms of degrading dyes and other organic pollutants as an environmentally friendly material for wastewater remediation.Herein,we report a new type of amorph...Metallic glasses have recently attracted great attention in terms of degrading dyes and other organic pollutants as an environmentally friendly material for wastewater remediation.Herein,we report a new type of amorphous catalyst Fe_(41)Co_(7)Cr_(15)Mo_(14)C_(15)B_(6)Y_(2) hollow balls.Results demonstrate that the catalyst can still completely decolorize the 20 mg/L methylene blue(MB)solution after reused for 50 times under conditions of pH=5,catalyst content 0.5 g/L,and temperature 80°C.The catalyst is easily broken during degradation,so the inner surface also provides additional active sites.The Fe_(41)Co_(7)Cr_(15)Mo_(14)C_(15)B_(6)Y_(2) amorphous alloy hollow balls were characterized by energy dispersive X-ray specroscopy(EDS),scanning electron microscopy(SEM)and X-ray photoelectron spectroscopy(XPS),respectively.The elements in the catalytic system have a synergistic catalytic effect.Redox cycle Fe^(2+)/Fe^(3+),Co^(2+)/Co^(3+)and Mo^(4+)/Mo^(6+) promote mutual conversion and accelerate the catalytic process of their reaction with H_(2)O_(2),forming a self-stable redox cycle process.Among them,Fe^(2+)promotes the conversion of Co^(3+)to Co^(2+),and Mo^(4+) promotes the conversion of Fe^(3+)to Fe^(2+),mainly Fe^(2+)and Co^(2+)react with H_(2)O_(2) to generate•OH.Mo and Cr elements form MoO_(2) and Cr_(2)O_(3) plasma compounds on the surface,which act as a protective film to make the catalyst more stable and be repeated used more frequently.展开更多
基金supported by the National Key R&D Program of China(Grant No.2021YFA1600704)the National Natural Science Foundation of China(Grant Nos.52203385 and 52171056)+3 种基金CNNC Science Fund for Talented Young Scholarsthe IMR Innovation Fund(Grant No.2021-ZD02)the Natural Science Foundation of Liaoning Province(Grant No.2022-BS-009)Young Elite Scientists Sponsorship Program by CAST(Grant No.YESS20220225)。
文摘As a classic in-situ reaction, the Al-TiO_(2) reaction is expected to prepare aluminum matrix composites with high thermal stability.In this study, it was found that the preparation method of ensuring sufficient reaction using higher temperatures in previous studies was not conducive to acquiring optimized high-temperature strength. With the increase of hot-pressing temperature and the extension of holding time, the in-situ reaction became more thorough, but the strength of the composites first increased and then decreased. Coarsening of the microstructure at high temperatures would lead to degradation of strength and controlling the in-situ reaction process by the hot-pressing parameters could optimize the mechanical properties of the composites. Strengthening mechanisms at room and high temperatures were studied, and it was found that the load-transfer and Orowan strengthening mechanisms are the main strengthening effects at room temperature, while the pinning effect of fine particles became more crucial at elevated temperatures. As a result, the coarsening of the reinforcing phases was more detrimental to the hightemperature strength. Therefore, an insufficient in-situ reaction led to more excellent mechanical properties, and the composite hot-pressed at 605℃ and held for 2 h exhibited the highest strength, which was 367 MPa at room temperature and 170 MPa at 350℃.
基金Project supported by the Research Fund of State Key Laboratory for Marine Corrosion and Protection of Luoyang Ship Material Research Institute (LSMRI)(KF190413)。
文摘Metallic glasses have recently attracted great attention in terms of degrading dyes and other organic pollutants as an environmentally friendly material for wastewater remediation.Herein,we report a new type of amorphous catalyst Fe_(41)Co_(7)Cr_(15)Mo_(14)C_(15)B_(6)Y_(2) hollow balls.Results demonstrate that the catalyst can still completely decolorize the 20 mg/L methylene blue(MB)solution after reused for 50 times under conditions of pH=5,catalyst content 0.5 g/L,and temperature 80°C.The catalyst is easily broken during degradation,so the inner surface also provides additional active sites.The Fe_(41)Co_(7)Cr_(15)Mo_(14)C_(15)B_(6)Y_(2) amorphous alloy hollow balls were characterized by energy dispersive X-ray specroscopy(EDS),scanning electron microscopy(SEM)and X-ray photoelectron spectroscopy(XPS),respectively.The elements in the catalytic system have a synergistic catalytic effect.Redox cycle Fe^(2+)/Fe^(3+),Co^(2+)/Co^(3+)and Mo^(4+)/Mo^(6+) promote mutual conversion and accelerate the catalytic process of their reaction with H_(2)O_(2),forming a self-stable redox cycle process.Among them,Fe^(2+)promotes the conversion of Co^(3+)to Co^(2+),and Mo^(4+) promotes the conversion of Fe^(3+)to Fe^(2+),mainly Fe^(2+)and Co^(2+)react with H_(2)O_(2) to generate•OH.Mo and Cr elements form MoO_(2) and Cr_(2)O_(3) plasma compounds on the surface,which act as a protective film to make the catalyst more stable and be repeated used more frequently.
