Tensile tests and notch toughness tests were conducted on Zr61Ti2Cu25Al12 glass （ZT） at room temperature and liquid-nitrogen temperature. The tensile strength of ZT was improved from 1.63 GPa at room temperature to ...Tensile tests and notch toughness tests were conducted on Zr61Ti2Cu25Al12 glass （ZT） at room temperature and liquid-nitrogen temperature. The tensile strength of ZT was improved from 1.63 GPa at room temperature to 1.72 GPa at liquid-nitrogen temperature. Micro-notches with a root radius of 1-3μm were introduced to test the notch toughness of ZT at room temperature and liquid-nitrogen temperature. The test results revealed that the notch toughness of ZT at liquid-nitrogen temperature is comparable to that of ZT at room temperature. The combination of high yield strength and notch toughness of ZT at liquid-nitrogen temperature is comparable to that of the best cryogenic engineering materials.展开更多
A liquid-nitrogen-cooling friction stir spot welding(C-FSSW) technology was developed for welding AZ31 magnesium alloy sheets. The liquid-nitrogen cooling degraded the deformability of the welded materials such that t...A liquid-nitrogen-cooling friction stir spot welding(C-FSSW) technology was developed for welding AZ31 magnesium alloy sheets. The liquid-nitrogen cooling degraded the deformability of the welded materials such that the width of interfacial cracks increased with increasing cooling time. The grain size of the stirred zone(SZ) and the heat-affected zone(HAZ) of the C-FSSW-welded joints decreased, whereas that of the thermomechanically affected zone(TMAZ) increased with increasing cooling time. The maximum tensile shear load of the C-FSSW-welded joints welded with a cooling time of 5 or 7 s was larger than that of the friction stir spot welding(FSSW)-welded joint, and the tensile shear load decreased with increasing cooling time. The microhardness of the C-FSSW-welded joints was greater than that of the FSSW-welded joint. Moreover, the microhardness of the SZ and the HAZ of the C-FSSW-welded joints increased, whereas that of the TMAZ decreased, with increasing cooling time.展开更多
Three kinds of autotrophic bioleaching bacteria strains,including mesophilic and acidophilic ferrous ion-oxidizing bacteria Acidithiobacillus ferrooxidans(A.ferrooxidans),mesophilic and acidophilic sulfur-oxidizing ba...Three kinds of autotrophic bioleaching bacteria strains,including mesophilic and acidophilic ferrous ion-oxidizing bacteria Acidithiobacillus ferrooxidans(A.ferrooxidans),mesophilic and acidophilic sulfur-oxidizing bacteria Acidithiobacillus thiooxidans(A.thiooxidans),and moderately thermophilic sulfur-oxidizing bacteria.4cidianus brierleyi,were cryopreserved in liquid nitrogen and their ferrous ion-or sulfur-oxidizing activities were investigated and compared with the original ones.The results revealed that ferrous ion/sulfur oxidation activities of the strains were almost equal before and after cryopreservation.Glycerin was used as cryoprotective agent.In conclusion,liquid-nitrogen cryopreservation is a simple and effective method for autotrophic bioleaching microorganisms.展开更多
In the present study, titanium plate was treated by a novel method of laser quenching, simultaneously combined with liquidnitrogen cryogenics(LQLNC). The microstructure and properties of the titanium plate after treat...In the present study, titanium plate was treated by a novel method of laser quenching, simultaneously combined with liquidnitrogen cryogenics(LQLNC). The microstructure and properties of the titanium plate after treatment were investigated by X-ray diffraction, scanning electron microscopy, energy dispersive spectrometry, Vickers hardness testing, and friction wear testing.The results show that the treated titanium plate is covered by a nitrided layer with a homogeneous thickness of about 60 μm,while the nitrided layer consists of Ti N and α-Ti phases. Compared to general laser quenching, the LQLNC treatment increases the hardness and wear resistance of the surface-modified layer of the titanium plate. As a result of grain refinement in the nitrided layer, the cracking induced by the rapid solidification of the conventional laser-quenching process has also been effectively solved.展开更多
基金supported by ARO-W911NF-12-1-0022 with partial support from DTRA-1-11-1-0064
文摘Tensile tests and notch toughness tests were conducted on Zr61Ti2Cu25Al12 glass （ZT） at room temperature and liquid-nitrogen temperature. The tensile strength of ZT was improved from 1.63 GPa at room temperature to 1.72 GPa at liquid-nitrogen temperature. Micro-notches with a root radius of 1-3μm were introduced to test the notch toughness of ZT at room temperature and liquid-nitrogen temperature. The test results revealed that the notch toughness of ZT at liquid-nitrogen temperature is comparable to that of ZT at room temperature. The combination of high yield strength and notch toughness of ZT at liquid-nitrogen temperature is comparable to that of the best cryogenic engineering materials.
基金financially supported by the National Natural Science Foundation of China (No.51375511)the Research Program of Basic Research and Frontier Technology of Chongqing of China (No.cstc2016jcyj A0167)+3 种基金the Science and Technology Project in the Field of Social Development of Shapingba District of Chongqing of China (No.SF201602)the Key Industry Technology Innovation Fund of Science and Technology Development Board of Xiangcheng District of Suzhou of China (No.XJ201608)the Science and Technology Project of Beibei District of Chongqing of China (No.2016-27)the Fundamental and Advanced Technology Research Funds of Chongqing (No.cstc2015jcyjBX0103)
文摘A liquid-nitrogen-cooling friction stir spot welding(C-FSSW) technology was developed for welding AZ31 magnesium alloy sheets. The liquid-nitrogen cooling degraded the deformability of the welded materials such that the width of interfacial cracks increased with increasing cooling time. The grain size of the stirred zone(SZ) and the heat-affected zone(HAZ) of the C-FSSW-welded joints decreased, whereas that of the thermomechanically affected zone(TMAZ) increased with increasing cooling time. The maximum tensile shear load of the C-FSSW-welded joints welded with a cooling time of 5 or 7 s was larger than that of the friction stir spot welding(FSSW)-welded joint, and the tensile shear load decreased with increasing cooling time. The microhardness of the C-FSSW-welded joints was greater than that of the FSSW-welded joint. Moreover, the microhardness of the SZ and the HAZ of the C-FSSW-welded joints increased, whereas that of the TMAZ decreased, with increasing cooling time.
基金Project(50621063)supported by Chinese Science Foundation for Distinguished GroupProject(2004CB619201)supported by the National Basic Research Program of China
文摘Three kinds of autotrophic bioleaching bacteria strains,including mesophilic and acidophilic ferrous ion-oxidizing bacteria Acidithiobacillus ferrooxidans(A.ferrooxidans),mesophilic and acidophilic sulfur-oxidizing bacteria Acidithiobacillus thiooxidans(A.thiooxidans),and moderately thermophilic sulfur-oxidizing bacteria.4cidianus brierleyi,were cryopreserved in liquid nitrogen and their ferrous ion-or sulfur-oxidizing activities were investigated and compared with the original ones.The results revealed that ferrous ion/sulfur oxidation activities of the strains were almost equal before and after cryopreservation.Glycerin was used as cryoprotective agent.In conclusion,liquid-nitrogen cryopreservation is a simple and effective method for autotrophic bioleaching microorganisms.
基金supported by the National High Technology Research and Development Program of China(Grant No.2012AA03A508)the National Natural Science Foundation of China(Grant Nos.U1360102,51275344)
文摘In the present study, titanium plate was treated by a novel method of laser quenching, simultaneously combined with liquidnitrogen cryogenics(LQLNC). The microstructure and properties of the titanium plate after treatment were investigated by X-ray diffraction, scanning electron microscopy, energy dispersive spectrometry, Vickers hardness testing, and friction wear testing.The results show that the treated titanium plate is covered by a nitrided layer with a homogeneous thickness of about 60 μm,while the nitrided layer consists of Ti N and α-Ti phases. Compared to general laser quenching, the LQLNC treatment increases the hardness and wear resistance of the surface-modified layer of the titanium plate. As a result of grain refinement in the nitrided layer, the cracking induced by the rapid solidification of the conventional laser-quenching process has also been effectively solved.
