The influences of two kinds of casting modules of metal casting （MC） and expandable pattern casting （EPC） on the corrosion behavior of Mg-11Gd-3Y alloy were studied by electrochemical measurements, scanning electr...The influences of two kinds of casting modules of metal casting （MC） and expandable pattern casting （EPC） on the corrosion behavior of Mg-11Gd-3Y alloy were studied by electrochemical measurements, scanning electron microscopy （SEM） observation, X-ray diffractometry （XRD） and X-ray photoelectron spectroscopy （XPS） analysis. It is found that the quantity of the Mg 24 （Gd, Y） 5 phase in MC is more than that in EPC due to the cooling rate. There is more alloying element dissolved in the matrix compared with MC. For EPC, the galvanic corrosion effect between the matrix and the Mg 24 （Gd, Y） 5 phase decreases and the corrosion resistance increases compared with the MC. The chief corrosion mode for Mg-11Gd-3Y alloy is pitting corrosion because most of the alloying elements are transformed into intermetallic phases. The average corrosion rate of the MC alloy in the immersion test is five times higher than that of EPC alloy and yttrium is present in the product film, which will provide increased protection for Mg-11Gd-3Y alloy. The electrochemical measurements and immersion test show that the EPC process increases the corrosion resistance compared with the MC Mg-11Gd-3Y alloy.展开更多
In order to characterize the effects of 17β estradiol （17β-E2） on the expression of IL-6, IL-11 and NF-κB in the human MG-63 osteohlast-like cell line, the expression of IL-6 was detected by RT-PCR, Northern blot...In order to characterize the effects of 17β estradiol （17β-E2） on the expression of IL-6, IL-11 and NF-κB in the human MG-63 osteohlast-like cell line, the expression of IL-6 was detected by RT-PCR, Northern blot and Western blot. The expression of IL-11 was determined by RTPCR, and NF-κB by Western blot. The results showed that 17β-E2 down-regulated the expression of IL-6 mRNA and protein, IL-11 mRNA and NF-κB protein in MG-63 cells. It was suggested that the expression of NF-κB, IL-6 and IL-11 in MG-63 cells could be suppressed by 17β-E2, and this might lend support to estrogen replacement therapy in postmenopausal women.展开更多
The effects of Sm on the microstructure and mechanical properties of Mg-11 Gd-2 Y-0.6 Al alloy were investigated by X-ray diffraction,optical microscopy,scanning electron microscopy,energy dispersive spectrometry and ...The effects of Sm on the microstructure and mechanical properties of Mg-11 Gd-2 Y-0.6 Al alloy were investigated by X-ray diffraction,optical microscopy,scanning electron microscopy,energy dispersive spectrometry and high resolution transmission electron microscopy.Based on the theory of edge—edge matching and electronegativity theory,the mechanism of grain refinement is discussed.The strengthening mechanism is expounded conveniently from fine grain strengthening,coherent strengthening,precipitation strengthening and grain boundary strengthening.The results show that the micro structure of Mg-11 Gd-2 Y-0.6 Al alloy is mainly composed of a-Mg matrix,Mg5 Gd and Mg24Y5 phases.The addition of Sm forms Mg41Sm5 phase in the alloy and refines the alloy.The addition of Sm significantly improves the mechanical properties of the alloy at room and high temperatures.When the addition of Sm is 3 wt%,the tensile strengths of the alloy at room temperature and high temperature(200℃)reach the maximum value 292 and 321 MPa,respectively.The fracture mode of the alloy at different temperatures is mainly brittle fracture and intercrystalline fracture.展开更多
The sliding friction and wear behaviors of Mg-11Y-5Gd-2Zn-0.5Zr （wt%） alloy were investigated under oil lubricant condition by pin-on-disk configuration with a constant sliding distance of 1,000 m in the temperature...The sliding friction and wear behaviors of Mg-11Y-5Gd-2Zn-0.5Zr （wt%） alloy were investigated under oil lubricant condition by pin-on-disk configuration with a constant sliding distance of 1,000 m in the temperature range of 25-200℃. Results indicate that the volumetric wear rates and average friction coefficients decrease with the increase of sliding speeds, and increase with the increase of test temperature below 150℃. The hard and thermally stable Mg12（Y,Gd）Zn phase with long-period stacking order structure in the alloy presents significant wear resistance, The wear mechanism below 100℃ is abrasive wear as a result of plastic extrusion deformation. The corporate effects of severe abrasive, oxidative, and delaminating wear result in the tribological mechanism above 100℃.展开更多
基金Project(2007CB613705)supported by the National Basic Research Program of China
文摘The influences of two kinds of casting modules of metal casting （MC） and expandable pattern casting （EPC） on the corrosion behavior of Mg-11Gd-3Y alloy were studied by electrochemical measurements, scanning electron microscopy （SEM） observation, X-ray diffractometry （XRD） and X-ray photoelectron spectroscopy （XPS） analysis. It is found that the quantity of the Mg 24 （Gd, Y） 5 phase in MC is more than that in EPC due to the cooling rate. There is more alloying element dissolved in the matrix compared with MC. For EPC, the galvanic corrosion effect between the matrix and the Mg 24 （Gd, Y） 5 phase decreases and the corrosion resistance increases compared with the MC. The chief corrosion mode for Mg-11Gd-3Y alloy is pitting corrosion because most of the alloying elements are transformed into intermetallic phases. The average corrosion rate of the MC alloy in the immersion test is five times higher than that of EPC alloy and yttrium is present in the product film, which will provide increased protection for Mg-11Gd-3Y alloy. The electrochemical measurements and immersion test show that the EPC process increases the corrosion resistance compared with the MC Mg-11Gd-3Y alloy.
文摘In order to characterize the effects of 17β estradiol （17β-E2） on the expression of IL-6, IL-11 and NF-κB in the human MG-63 osteohlast-like cell line, the expression of IL-6 was detected by RT-PCR, Northern blot and Western blot. The expression of IL-11 was determined by RTPCR, and NF-κB by Western blot. The results showed that 17β-E2 down-regulated the expression of IL-6 mRNA and protein, IL-11 mRNA and NF-κB protein in MG-63 cells. It was suggested that the expression of NF-κB, IL-6 and IL-11 in MG-63 cells could be suppressed by 17β-E2, and this might lend support to estrogen replacement therapy in postmenopausal women.
基金Project supported by the National Natural Science Foundation of China(51571084 and 51171059)Project of Scientific And Technological Research In Henan Province(152102210072)
文摘The effects of Sm on the microstructure and mechanical properties of Mg-11 Gd-2 Y-0.6 Al alloy were investigated by X-ray diffraction,optical microscopy,scanning electron microscopy,energy dispersive spectrometry and high resolution transmission electron microscopy.Based on the theory of edge—edge matching and electronegativity theory,the mechanism of grain refinement is discussed.The strengthening mechanism is expounded conveniently from fine grain strengthening,coherent strengthening,precipitation strengthening and grain boundary strengthening.The results show that the micro structure of Mg-11 Gd-2 Y-0.6 Al alloy is mainly composed of a-Mg matrix,Mg5 Gd and Mg24Y5 phases.The addition of Sm forms Mg41Sm5 phase in the alloy and refines the alloy.The addition of Sm significantly improves the mechanical properties of the alloy at room and high temperatures.When the addition of Sm is 3 wt%,the tensile strengths of the alloy at room temperature and high temperature(200℃)reach the maximum value 292 and 321 MPa,respectively.The fracture mode of the alloy at different temperatures is mainly brittle fracture and intercrystalline fracture.
基金supported by the National Natural Science Foundation of China (No. 51074106)Key HiTech Research and Development Program of China (No. 2009AA033501)National Key Technology R&D Program of China (No. 2011BAE22B01-5)
文摘The sliding friction and wear behaviors of Mg-11Y-5Gd-2Zn-0.5Zr （wt%） alloy were investigated under oil lubricant condition by pin-on-disk configuration with a constant sliding distance of 1,000 m in the temperature range of 25-200℃. Results indicate that the volumetric wear rates and average friction coefficients decrease with the increase of sliding speeds, and increase with the increase of test temperature below 150℃. The hard and thermally stable Mg12（Y,Gd）Zn phase with long-period stacking order structure in the alloy presents significant wear resistance, The wear mechanism below 100℃ is abrasive wear as a result of plastic extrusion deformation. The corporate effects of severe abrasive, oxidative, and delaminating wear result in the tribological mechanism above 100℃.
