Five experimental self-shielded flux cored wires are fabricated withdifferent amount of Fe_2O_3 in the flux. The effect of Fe_2O_3 on welding technology and mechanicalproperties of weld metals deposited by these wires...Five experimental self-shielded flux cored wires are fabricated withdifferent amount of Fe_2O_3 in the flux. The effect of Fe_2O_3 on welding technology and mechanicalproperties of weld metals deposited by these wires are studied. The results show that with theincrease of Fe_2O_3 in the mix, the melting point of the pretreated mix is increased. LiBaF_3 andBaFe_(12)O_(19), which are very low in inherent moisture, are formed after the pretreatment. Themechanical properties are evaluated to the weld metals. The low temperature notch toughness of theweld metals is increased linearly with the Fe_2O_3 content in the flux due to the balance betweenFe_2O_3 and residual Al in the weld metal. The optimum Fe_2O_3 content in flux is 2.5 percent approx3.5 percent.展开更多
The lap joint of T2 copper plate and 1060 pure aluminum plate was made by using the plasma arc welding method with adding Fe_(2)O_(3)nanoparticles in different proportions.The research analysis found that the thicknes...The lap joint of T2 copper plate and 1060 pure aluminum plate was made by using the plasma arc welding method with adding Fe_(2)O_(3)nanoparticles in different proportions.The research analysis found that the thickness of the IMC(intermetallic compound)and eutect-ic region decreased after the addition of nanoparticles due to its inhibitory effect.When the proportion of Fe_(2)O_(3)nanoparticles is 3%,the in-terface intermetallic compound layer is the thinnest.However,after this ratio is continuously increased,the inhibition effect is weakened by the agglomeration of nanoparticles,and the thickness begins to increase significantly.The mechanical and electrical properties of the joint are mainly affected by the thickness of the IMC layer.Excessive nanoparticles are agglomerated into large particles with high resistivity.Therefore,the tensile strength and relative electrical conductivity of the joint are first increasing and then decreasing with the increase of nanoparticle ratio.When the proportion of nanoparticles is 3%,the tensile strength and electrical conductivity are maximum.展开更多
光电化学(PEC)分解水是一种清洁可持续的获取氢燃料的方法,其中产氧半反应(OER)是制约整个水分解过程效率的关键步骤.因此,光阳极的性能是决定太阳能到氢能转化效率的关键因素.在各种水氧化光阳极材料中,赤铁矿(α-Fe_(2)O_(3))因具有...光电化学(PEC)分解水是一种清洁可持续的获取氢燃料的方法,其中产氧半反应(OER)是制约整个水分解过程效率的关键步骤.因此,光阳极的性能是决定太阳能到氢能转化效率的关键因素.在各种水氧化光阳极材料中,赤铁矿(α-Fe_(2)O_(3))因具有良好的化学稳定性、合适的带隙(~2.1 eV)、无毒、储量丰富等优点而成为最有前途的光阳极材料之一.然而,α-Fe_(2)O_(3)丰富的受体表面态和缓慢的水氧化动力学导致光生电荷复合严重,限制了其在光电化学中的实际应用.因此,有必要对α-Fe_(2)O_(3)进行表面工程设计以提高水氧化效率.本文提出了一种新方法,以金属有机框架(Ti-MOFs)为模板,在Ti-Fe_(2)O_(3)表面煅烧合成TiO_(2)层,然后将富活性位点的ZIF-67加载在TiO_(2)/Ti-Fe_(2)O_(3)上作为助催化剂,制备出具有较好光电化学性能的ZIF-67/TiO_(2)/Ti-Fe_(2)O_(3)复合光阳极.X射线衍射、高分辨透射电镜、X射线光电子能谱和拉曼光谱等表征结果证实成功合成了ZIF-67/TiO_(2)/Ti-Fe_(2)O_(3).同时,氮气等温吸附脱附曲线和表面接触角测试结果表明,MOFs衍生的TiO_(2)为介孔材料.采用表面光伏技术、光致发光光谱、飞秒-瞬态吸收光谱和电化学阻抗谱分析,研究了光生电荷的分离和复合行为.结果表明,MOFs衍生的TiO_(2)不仅可以作为钝化层有效抑制了表面复合,还作为Ti-Fe_(2)O_(3)的电子阻挡层,显著减少了电子向表面的流失,从而大大提高了Ti-Fe_(2)O_(3)表面和体相的电荷分离效率.进一步的累积电荷量测试、电化学阻抗谱和Bode图分析显示,负载MOFs衍生TiO_(2)后,可以明显促进光生空穴向电解质的注入,其多孔结构也可以增加反应接触面积,这有利于光生电荷在固液界面传输.此外,理论计算结果表明,Ti-Fe_(2)O_(3)水氧化速控步骤的能垒(ΔG=3.38 eV)明显高于TiO_(2)(ΔG=1.67 eV),说明OER更容易在TiO_(2)/Ti-Fe_(2)O_(3)表面发生,这与其光电流密度结果一致.为进一步提高反应活性和加快水氧化动力学,负载助催化剂ZIF-67后,ZIF-67/TiO_(2)/Ti-Fe_(2)O_(3)复合光阳极实现了较好的光电化学性能,其在1.23 V vs.RHE时光电流密度高达4.04 mA cm^(‒2),是Ti-Fe_(2)O_(3)的9.3倍,并且复合光阳极的入射光子电流转换效率和空穴注入效率分别达到93%(390 nm)和91%.综上所述,本研究通过MOFs衍生的TiO_(2)和ZIF-67助催化剂改性α-Fe_(2)O_(3)光阳极,显著提升了其光电化学水氧化性能.其中,MOFs衍生TiO_(2)不仅优化了电荷分离,还促进了光生空穴的注入,从而显著提高其光电化学水氧化性能.本研究为构筑高性能的有机-无机杂化光阳极提供了新思路.展开更多
文摘Five experimental self-shielded flux cored wires are fabricated withdifferent amount of Fe_2O_3 in the flux. The effect of Fe_2O_3 on welding technology and mechanicalproperties of weld metals deposited by these wires are studied. The results show that with theincrease of Fe_2O_3 in the mix, the melting point of the pretreated mix is increased. LiBaF_3 andBaFe_(12)O_(19), which are very low in inherent moisture, are formed after the pretreatment. Themechanical properties are evaluated to the weld metals. The low temperature notch toughness of theweld metals is increased linearly with the Fe_2O_3 content in the flux due to the balance betweenFe_2O_3 and residual Al in the weld metal. The optimum Fe_2O_3 content in flux is 2.5 percent approx3.5 percent.
基金This work was supported by the National Natural Science Foundation of China(No.52165045).
文摘The lap joint of T2 copper plate and 1060 pure aluminum plate was made by using the plasma arc welding method with adding Fe_(2)O_(3)nanoparticles in different proportions.The research analysis found that the thickness of the IMC(intermetallic compound)and eutect-ic region decreased after the addition of nanoparticles due to its inhibitory effect.When the proportion of Fe_(2)O_(3)nanoparticles is 3%,the in-terface intermetallic compound layer is the thinnest.However,after this ratio is continuously increased,the inhibition effect is weakened by the agglomeration of nanoparticles,and the thickness begins to increase significantly.The mechanical and electrical properties of the joint are mainly affected by the thickness of the IMC layer.Excessive nanoparticles are agglomerated into large particles with high resistivity.Therefore,the tensile strength and relative electrical conductivity of the joint are first increasing and then decreasing with the increase of nanoparticle ratio.When the proportion of nanoparticles is 3%,the tensile strength and electrical conductivity are maximum.
文摘光电化学(PEC)分解水是一种清洁可持续的获取氢燃料的方法,其中产氧半反应(OER)是制约整个水分解过程效率的关键步骤.因此,光阳极的性能是决定太阳能到氢能转化效率的关键因素.在各种水氧化光阳极材料中,赤铁矿(α-Fe_(2)O_(3))因具有良好的化学稳定性、合适的带隙(~2.1 eV)、无毒、储量丰富等优点而成为最有前途的光阳极材料之一.然而,α-Fe_(2)O_(3)丰富的受体表面态和缓慢的水氧化动力学导致光生电荷复合严重,限制了其在光电化学中的实际应用.因此,有必要对α-Fe_(2)O_(3)进行表面工程设计以提高水氧化效率.本文提出了一种新方法,以金属有机框架(Ti-MOFs)为模板,在Ti-Fe_(2)O_(3)表面煅烧合成TiO_(2)层,然后将富活性位点的ZIF-67加载在TiO_(2)/Ti-Fe_(2)O_(3)上作为助催化剂,制备出具有较好光电化学性能的ZIF-67/TiO_(2)/Ti-Fe_(2)O_(3)复合光阳极.X射线衍射、高分辨透射电镜、X射线光电子能谱和拉曼光谱等表征结果证实成功合成了ZIF-67/TiO_(2)/Ti-Fe_(2)O_(3).同时,氮气等温吸附脱附曲线和表面接触角测试结果表明,MOFs衍生的TiO_(2)为介孔材料.采用表面光伏技术、光致发光光谱、飞秒-瞬态吸收光谱和电化学阻抗谱分析,研究了光生电荷的分离和复合行为.结果表明,MOFs衍生的TiO_(2)不仅可以作为钝化层有效抑制了表面复合,还作为Ti-Fe_(2)O_(3)的电子阻挡层,显著减少了电子向表面的流失,从而大大提高了Ti-Fe_(2)O_(3)表面和体相的电荷分离效率.进一步的累积电荷量测试、电化学阻抗谱和Bode图分析显示,负载MOFs衍生TiO_(2)后,可以明显促进光生空穴向电解质的注入,其多孔结构也可以增加反应接触面积,这有利于光生电荷在固液界面传输.此外,理论计算结果表明,Ti-Fe_(2)O_(3)水氧化速控步骤的能垒(ΔG=3.38 eV)明显高于TiO_(2)(ΔG=1.67 eV),说明OER更容易在TiO_(2)/Ti-Fe_(2)O_(3)表面发生,这与其光电流密度结果一致.为进一步提高反应活性和加快水氧化动力学,负载助催化剂ZIF-67后,ZIF-67/TiO_(2)/Ti-Fe_(2)O_(3)复合光阳极实现了较好的光电化学性能,其在1.23 V vs.RHE时光电流密度高达4.04 mA cm^(‒2),是Ti-Fe_(2)O_(3)的9.3倍,并且复合光阳极的入射光子电流转换效率和空穴注入效率分别达到93%(390 nm)和91%.综上所述,本研究通过MOFs衍生的TiO_(2)和ZIF-67助催化剂改性α-Fe_(2)O_(3)光阳极,显著提升了其光电化学水氧化性能.其中,MOFs衍生TiO_(2)不仅优化了电荷分离,还促进了光生空穴的注入,从而显著提高其光电化学水氧化性能.本研究为构筑高性能的有机-无机杂化光阳极提供了新思路.
