Electrical conductivity of （Na3AlF6-40%K3AlF6）-AlF3-Al2O3 melts

The effects of contents of AlF3 and Al2O3, and temperature on electrical conductivity of （Na3AlF6-40%K3AlF6）- AlF3-Al2O3 were studied by continuously varying cell censtant （CVCC） technique. The results show that the conductivities of melts increase with the increase of temperature, but by different extents. Every increasing 10 ℃ results in an increase of 1.85 × 10^-2, 1.86× 10^-2, 1.89 × 10^-2 and 2.20 × 10^-2 S/cm in conductivity for the （Na3AlF6-40%K3AlF6）-AlF3 melts containing 0%, 20%, 24%, and 30% AlF3, respectively. An increase of every 10 ℃ in temperature results an increase about 1.89× 10^-2, 1.94 × 10^-2, 1.95 × 10^-2, 1.99× 10^-2 and 2.10× 10^-2 S/cm for （Na3AlF6-40%K3AlF6）-AlF3-Al2O3 melts containing 0%, 1%, 2%, 3% and 4% Al2O3, respectively. The activation energy of conductance was calculated based on Arrhenius equation. Every increasing 1% of AlF3 results in a decrease of 0.019 and 0.020 S/cm in conductivity for （Na3AlF6-40%K3AlF6）-AlF3 melts at 900 and 1 000 ℃, respectively. Every increase of 1% Al2O3 results in a decrease of 0.07 S/cm in conductivity for （Na3AlF6-40%K3AlF6）-AlF3-Al2O3 melts. The activation energy of conductance increases with the increase in content of AlF3 and Al2O3.     

Electrical conductivity of (Na_3AlF_6-40%K_3AlF_6)-AlF_3-Al_2O_3 melts

The effects of contents of AlF3 and Al2O3,and temperature on electrical conductivity of (Na3AlF6-40%K3AlF6)-AlF3-Al2O3 were studied by continuously varying cell constant (CVCC) technique.The results show that the conductivities of melts increase with the increase of temperature,but by different extents.Every increasing 10 ℃ results in an increase of 1.85×10-2,1.86×10-2,1.89×10-2 and 2.20×10-2 S/cm in conductivity for the (Na3AlF6-40%K3AlF6)-AlF3 melts containing 0%,20%,24%,and 30% AlF3,respectively.An increase of every 10 ℃ in temperature results an increase about 1.89×10-2,1.94×10-2,1.95×10-2,1.99×10-2 and 2.10×10-2 S/cm for (Na3AlF6-40%K3AlF6)-AlF3-Al2O3 melts containing 0%,1%,2%,3% and 4% A12O3,respectively.The activation energy of conductance was calculated based on Arrhenius equation.Every increasing 1% of AlF3 results in a decrease of 0.019 and 0.020 S/cm in conductivity for (Na3AlF6-40%K3AlF6)-AIF3 melts at 900 and 1 000 ℃,respectively.Every increase of 1% Al2O3 results in a decrease of 0.07 S/cm in conductivity for (Na3AlF6-40%K3AlF6)-AlF3-Al2O3 melts.The activation energy of conductance increases with the increase in content of AlF3 and Al2O3.     

Fabrication and anodic polarization behavior of lead-based porous anodes in zinc electrowinning

A new type of lead-based porous anode in zinc electrowinning was prepared by negative pressure infiltration. The anodic polarization potential and corrosion rate were studied and compared with those of traditional fiat anodes （Pb-0.8%Ag） used in industry. The anode corrosion rate was determined by anode actual current density and microstructure. The results show that the anodic oxygen evolution potential decreases first and then increases with the decrease of pore diameter. The anodic potential decreases to the lowest value of 1.729 V at the pore diameter of 1.25-1.60 mm. The porous anode can decrease its actual current density and thus decrease the anodic corrosion rate. When the pore diameter is 1.60-2.00 mm, the anodic relative corrosion rate reaches the lowest value of 52.1%.     

工艺条件对铝电解NiFe2O4基惰性阳极热应力的影响

近年来惰性阳极已成为铝电解工业中的研究热点.以有限元软件ANSYS为开发平台,建立了单个惰性阳极实际工作条件下的有限元模型,以降低热应力,优化热应力分布为目标,研究了工艺条件包括电解质温度、电流强度、极距、阳极浸入电解质深度、环境温度、阳极与环境的换热系数等参数对惰性阳极热应力分布的影响.结果表明,在实际的工作条件下,阳极与电解质相接触的界面附近存在的轴向拉应力,是阳极开裂的主要原因.电解质温度和阳极浸入电解质深度是影响阳极热应力的两个最主要因素.温度升高、阳极浸入电解质深度增加都会使阳极的热应力分布变差.当电解温度由750℃上升到970℃时,第1主应力最大值和最小值绝对值分别上升了29.7%和29.6%,阳极浸入电解质深度由0.01 m变化至0.10 m时,第一主应力最大值和最小值绝对值分别上升了52.1%和65%.其他参数对阳极热应力分布影响很小.     

Nd对锌电积用Pb-Ag合金阳极性能的影响

采用恒流极化、失重法和抗拉强度测试研究不同含量Nd的加入对锌电积用铅银合金阳极主要性能(稳定阳极电位、耐腐蚀性能及力学性能)的影响,并在此基础上采用循环伏安(CV)和计时电位(CP)等电化学手段对恒流极化条件下Nd的作用机理进行研究。结果表明:0.03%Nd(质量分数)加入可以将Pb-Ag合金的抗拉强度提高21.8%;锌电积条件下,铅阳极表面腐蚀膜主要成分为PbO2及PbSO4,Nd加入可以抑制PbSO4的形成,从而明显降低阳极腐蚀速率;由于Nd能降低析氧过电位,且对高阻抗PbSO4的生成具有抑制作用,使得Pb-Ag合金的阳极电位亦有一定程度的下降。Nd对锌电积阳极主要性能均有较大程度的改进作用,是很好的锌电积阳极改性剂,具有较好的工业应用前景。     

二步煅烧法制备高振实密度钛酸锂负极材料

以Li2CO3和纳米TiO2为原料,通过二步煅烧固相反应法制备Li4Ti5O12负极材料。研究前驱体球磨以及球磨时间对合成Li4Ti5O12样品振实密度和电化学性能的影响。借助XRD、SEM、振实密度仪和充放电测试仪、电化学综合测试仪表征Li4Ti5O12材料的物理性能和电化学性能。结果表明:球磨工艺能够提高Li4Ti5O12的纯度,并有效提高其振实密度和电化学性能;球磨时间为2 h时,所得材料的振实密度达1.70 g/cm3,0.1C首次放电比容量为174 mA.h/g,5C放电比容量达124.2 mA.h/g。     

Li4Ti5O12/TiN复合材料的制备及电化学性能

以尿素为氮源,采用高温热处理方法在Li4Ti5O12表面自生长一层纳米尺寸厚度的TiN导电包覆膜。利用DSC-TG、Raman、TEM、FT-IR、XRD及恒流充放电等测试手段,研究热处理工艺对材料结构、形貌及电化学性能的影响。结果表明:使用适中的尿素原料含量可以获得均匀连续、厚度适中的TiN导电膜,较高的热处理温度有利于促进TiN的生成,而较短的热处理时间可以保持材料物相的纯净和较高结晶度。在尿素含量10%(质量分数)、热处理温度800℃、热处理时间20 min的工艺条件下,所制备的复合材料的容量和倍率性能最优,0.2C和3C初始放电比容量分别达到162.4和130.2 mA.h/g。     

LiF对Na_3AlF_6-K_3AlF_6-AlF_3熔体初晶温度和Al_2O_3溶解度的影响

采用步冷曲线法测定Na3AlF6-K3AlF6-AlF3-LiF熔体的初晶温度,采用旋转刚玉片质量损失法测定Al2O3在Na3AlF6-K3AlF6-AlF3-LiF熔体中的溶解度。结果表明:当LiF添加量在0～4%范围内时,每添加1%LiF使Na3AlF6-K3AlF6-AlF3熔体的初晶温度降低3～4.7℃,小于Na3AlF6-AlF3熔体中添加LiF后初晶温度的影响;在0～3%的范围内,每添加1%LiF将使Al2O3在Na3AlF6-K3AlF6-AlF3熔体中的溶解度降低0.23%～0.55%。     

太阳电池用CuInSe_2薄膜的电化学可控沉积

采用恒电位电沉积法制备了CuInSe_2薄膜材料,通过循环伏安分析探讨了Cu~(2+)、In~(3+)和H_2SeO_3单独沉积和共沉积的电化学行为,并研究了沉积电位对薄膜化学计量组成、形貌和物相组成的影响规律。研究表明:柠檬酸根离子对Cu~(2+)和H_2SeO_3具有络合作用,而对In~(3+)的络合不明显。共沉积时,Cu最先还原,然后诱导Se的沉积,两者反应形成的铜硒化合物Cu_xSe又诱导In的欠电位沉积,并与之反应生成CuInSe_2。在阴极电位为-0.58～-0.90Vvs.SCE时出现了不随电位变化的极限还原电流,在该电位范围内进行电沉积获得了化学计量组成稳定可控且相对致密平整的CuInSe_2薄膜。