LOW TEMPERATURE ALUMINUM FLOATING ELECTROLYSIS IN HEAVY ELECTROLYTE Na_3AlF_6-AlF_3-BaC1_2-NaCl BATH SYSTEM

1. IntroductionSince the Hall--Heroult process was invented one hundred years ago, it has been the onlyaluminum production method in the w..ldll]. The process has many weak points, such aslow unit productivity; low energy utilization, less than 50%; high electrolytic temperature,usually at 950ap; high consumption of carbon material; serious environmental pollutionand so on. It is well known that the melting point of aluminum is 660ap, therefore, aluminum electrolysis at the range of 700--800C…     

Coupled heat/mass-balance model for analyzing correlation between excess AlF3 concentration and aluminum electrolyte temperature

The influence of aluminum electrolyte component on its temperature is an important issue within the field of aluminum reduction with pre-baked cells. The characteristic correlation between excess AlF3 concentration and aluminum electrolyte temperature was explored through the modeling of heat and mass transfer processes in industrial pre-baked aluminum reduction cells. A coupled heat/mass-balance model was derived theoretically from the mass and energy balance of an electrolysis cell, and then was simplified properly into a practical expression. The model demonstrates that if environmental temperature and Al2O3 concentration keep constant, the excess AlF3 concentration decreases with the aluminum electrolyte temperature linearly and its decrease rate is dependent on the heat transfer property of aluminum electrolyte, side wall and cell shell. Secondly, experiments were conducted on site with two industrial cells in an aluminum electrolysis plant. Excess AlF3 concentration and aluminum electrolyte temperature were obtained simultaneously together with other parameters such as Al2O3, CaF2, MgF2 and LiF concentrations. Results show that the maximum absolute error between the tested value and the calculated value of excess AlF3 concentration using the proposed model is less than 2%. This reveals that the coupled heat/mass-balance model can appropriately characterize the correlation between excess AlF3 concentration and aluminum electrolyte temperature with good accuracy and practicability.     

等离子球化制备球形CaF2/BaF2共晶粉末*

探究了使用大气等离子喷涂设备制备适合热喷涂使用的球形CaF2/BaF2共晶粉末的可能性。68%BaF2、32%CaF2粉末(质量分数)经过1 100℃真空烧结后,形成致密的块状氟化物共晶。机械破碎后的氟化物共晶经过等离子焰流重熔后得到了球形的氟化物共晶。使用F14-1流动性和松装密度测定仪测量球化前后粉末的流动性和松装密度。采用扫描电子显微镜,XRD表征球化前后粉末的形貌和物相组成。结果表明:球化后的粉末呈现较好的球形,球化后粉末的流动性和松装密度较球化前也有较大的改善:球化后共晶粉末的流动时间为55.20s/50g,松装密度为1.89g/cm3;另外,球化后共晶粉末还表现出良好的高温润滑性能:含有10%CaF2/BaF2共晶(质量分数)的镍基涂层在600℃和800℃的平均摩擦因数都小于0.3。     

Results from 100 h electrolysis testing of NiFe2O4 based cermet as inert anode in aluminum reduction

1 Introduction Since the Hall-Héroult process was applied in aluminum production, an inert anode was always the target that the aluminum industry was seeking for in the new technology field[1]. Some selection criteria have been defined in order to ident…     

添加BaF_2/CaF_2对爆炸喷涂Cr_3C_2基金属陶瓷涂层性能的影响

采用爆炸喷涂制备添加BaF2/CaF2共晶的Cr3C2基金属陶瓷涂层,通过X射线衍射仪(XRD)、扫描电镜(SEM)及显微硬度仪等检测方法观测了喷涂粉形貌、相组成及涂层微观组织、硬度等性能,探讨了BaF2/CaF2共晶的加入方式及其含量对爆炸喷涂Cr3C2基金属陶瓷涂层性能的影响,结果显示:10%的BaF2/CaF2共晶与Cr3C2-25%NiCr粉体经高能球磨1h,粉体粒度最小,尺寸均匀性最高。爆炸喷涂后涂层组织致密,孔隙率小于0.8%;共晶的加入,降低了涂层的显微硬度(Hv),且随加入量的增加,涂层硬度及孔隙率逐步降低;共晶与NiCr合金的预先球磨,有助于提高涂层均匀致密性和硬度,孔隙率为0.2%,显微硬度(Hv)为665.6。     

等离子喷涂制备WC-Co-Cu-BaF_2/CaF_2自润滑耐磨涂层及其高温摩擦性能

通过大气等离子喷涂方法,使用自制的含有WC-Co、Cu和BaF2/CaF2共晶体的复合喷涂粉末,制备出WC-Co-Cu-BaF2/CaF2自润滑耐磨涂层。在200℃、400℃和600℃下进行WC-Co-Cu-BaF2/CaF2涂层和WC-Co涂层的高温摩擦试验,用扫描电镜观察涂层磨损表面微观形貌。结果表明:200℃时,由于WC-Co-Cu-BaF2/CaF2涂层摩擦产物层中含有的WC硬质颗粒引起磨粒磨损,该涂层摩擦因数和磨损率相对较高。而400℃和600℃时,WC-Co-Cu-BaF2/CaF2涂层的摩擦产物层中均无WC颗粒存在,且由于涂层中Cu和BaF2/CaF2等固体润滑剂的作用,生成的摩擦产物层光滑且致密,涂层的摩擦因数和磨损率均较低,在400～600℃下表现出比WC-Co涂层优异的耐磨性能。     

等离子喷涂制备WC-Co-Cu-BaF2/CaF2自润滑耐磨涂层及其高温摩擦性能

通过大气等离子喷涂方法,使用自制的含有WC-Co、Cu和BaF2/CaF2共晶体的复合喷涂粉末,制备出WC-Co-Cu-BaF2/CaF2自润滑耐磨涂层。在200℃、400℃和600℃下进行WC-Co-Cu-BaF2/CaF2涂层和WC-Co涂层的高温摩擦试验,用扫描电镜观察涂层磨损表面微观形貌。结果表明:200℃时,由于WC-Co-Cu-BaF2/CaF2涂层摩擦产物层中含有的WC硬质颗粒引起磨粒磨损,该涂层摩擦因数和磨损率相对较高。而400℃和600℃时,WC-Co-Cu-BaF2/CaF2涂层的摩擦产物层中均无WC颗粒存在,且由于涂层中Cu和BaF2/CaF2等固体润滑剂的作用,生成的摩擦产物层光滑且致密,涂层的摩擦因数和磨损率均较低,在400～600℃下表现出比WC-Co涂层优异的耐磨性能。     

高能球磨制备PS304纳米复合粉

将Ni，Cr，Cr2O3，Ag和BaF2／CaF2按PS304成分配比进行机械合金化（MA）。研究了不同的球磨时间对粉末性能的影响，并对机械合金化粉末的物相，晶粒尺寸及粉末形貌作了测定和分析讨论。研究发现，机械合金化使晶粒细化，其中Cr2O3，Ag的晶粒尺寸（球磨15h）可达50nm以下。CaF2和BaF2的X射线衍射峰随球磨时间的延长而逐渐地减弱直至消失，同时在整个球磨过程中，并没有发现CaF2或BaF2的新相生成，氟化物可能形成了过饱和固溶体。EDX分析表明，得到的粉为复合粉。     

一种含氟化镁电解质体系的温度、密度和导电度论证

本文对一种在生产中使用的含镁铝电解质体系的温度、密度、导电度利用经验公式进行了论证。通过论证得出如能通过技术手段和管理手段对电解质中各成份含量进行精细控制，电解生产可以在较低温度下高效运行；该电解质体系和铝液的密度差在一些情况下较小，生产中注意提前调控；该电解质体系和低分子比高氟化钙电解质体系的导电度相当。     

电解加钛对6063铝合金的晶粒细化效果

向铝电解槽中加入少量的二氧化钍，可生产含少量钍的电解低钍铝合金锭。本文用电解低钍铝合金锭配置6063变形铝合金，研究了这种加钍方式对6063铝合金的晶粒细化效果及细化机理．并与铝钍中间合金．对6063铝合金的细化效果做了对比。结果表明，电解加钍的细化效果优于用铝钍中间合金加钍的细化效果。且随保温时间的延长。有更好的抗晶粒细化衰退效果。用电解低钍铝合金配置6063铝合金是完全可行的，用电解的方法加入二氧化钍是一种质优价廉的新方法。     

偏硼酸钠体系铝合金仿木纹交流电解工艺

在普通偏硼酸钠－硼酸仿木纹电解液的基础上,通过添加碳酸钠作为刻蚀剂,添加磷酸钠作为增粘剂,得到了一种新型的偏硼酸钠体系仿木纹电解液。分析讨论电解液组成及工艺条件对仿木纹电解效果的影响后,发现碳酸钠和磷酸钠质量浓度是主要影响因素,工艺条件的影响是相互制约的。该新工艺具有电解液稳定,获得的木纹逼真,操作简便等特点     

Preliminary testing of NiFe2O4-NiO-Ni cermet as inert anode in Na3AlF6-AlF3 melts

1 Introduction It is well known that the current aluminum reduction cell with carbon consumable anode has many disadvantages. So the concept of inert anode was introduced, with which the disadvantages can be avoided completely. A lot of research work has…     

Electrolytic preparation of Al-Ca master alloy on liquid Al cathode

1　ＩＮＴＲＯＤＵＣＴＩＯＮＡｓａｎｅｗｌｙｄｅｖｅｌｏｐｉｎｇｓｕｐｅｒ ｐｌａｓｔｉｃａｌｕｍｉｎｕｍａｌｌｏｙ ,Ａｌ Ｃａａｌｌｏｙｈａｓｎｏｔｏｎｌｙｇｏｏｄｐｌａｓｔｉｃｉｔｙ ,ｂｕｔａｌ ｓｏｇｏｏｄｍｅｃｈａｎｉｃａｌｐｒｏｐｅｒｔｙ ,ｇｏｏｄｗｅｌｄｉｎｇｐｒｏｐｅｒｔｙａｎｄｓｔｒｏｎｇｒｅｓｉｓｔａｎｃｅｏｆｃｏｒｒｏｓｉｏｎａｆｔｅｒｂｅｉｎｇｆｏｒｍｅｄ .Ｔｈｅｒｅｆｏｒｅ ,ａｌｏｔｏｆｍｅｔａｌｌｕｒｇｉｃａｌｓｃｉｅｎｔｉｓｔｓｈａｖｅｄｅｖｏｔ ｅｄｔｏｔｈｅｒｅｓｅａ…     

氟化钾对固态铝电解质物相的影响

本文用X-射线衍射法研究了KF与冰晶石的反应及其对固态铝电解质物相的影响。研究表明:KF与Na3AlF6(冰晶石)在熔盐中能够发生化学反应,无论是在酸性还是碱性电解质中产物都有K2NaAlF6(钾冰晶石),但在酸性电解质中其反应产物同时有K2NaAl3F12和K2NaAlF6两种物相。随着KF含量的增加以及电解质酸度的增强,K2NaAl3F12的含量增加。本文还提出了K2NaAl3F12物质的生成机理以及对同时含CaF2、LiF、MgF2和KF的铝电解质的物相进行了鉴定。对分子比定义为碱性氟化物与AlF3的摩尔比进行了验证,表明只有这种定义才能够真正体现电解质的酸碱性。     

润滑相尺寸对自润滑膜形成的影响

采用高能球磨制备细小的复合粉末,再通过感应烧结制备耐高温自润滑IS304涂层,涂层致密且润滑相明显细化,其中Ag粉尺寸为5μm左右、氟化物尺寸小于2μm,且氟化物粒子与Cr2O3粒子形成复合结构。室温时IS304摩擦系数较大,磨损机制主要为微观脆性断裂;随着温度的升高,由于润滑相尺寸减小、且氟化物粒子与Cr2O3粒子形成复合结构,使得摩擦副在高速滑动过程中接触点的瞬态温度迅速升高,此瞬态温度有效地激活了氟化物粒子的润滑性能,在摩擦力和压力的作用下,氟化物粒子经塑性变形后形成表面润滑膜,使得接触面的摩擦系数急剧减小。有限元计算也表明润滑相的细化和分布位置的改变可明显提高润滑相的瞬态温度。     

Cu-Ni-Al金属阳极抗氧化耐腐蚀性能研究

本文对铝电解阳极材料Cu—Ni—Al合金进行抗氧化耐腐蚀性能测试，结果说明Cu—Ni—Al阳极在空气和氧气中具有良好的抗氧化性，其中温度和气氛对该合金材料抗氧化影响很大；在不同条件下，电解质组成为NaCl-CaF2-Al2O3的熔盐中溶解损失比较小。在熔盐中腐蚀速率随着温度升高、电解质分子比降低而增大。     

Electrolytic properties and element migration in Ni-TiB_2/Al_2O_3composite cathode

With alumina sol as binder and Ni metal as sintering aids,the Ni-TiB_2/Al_2 O_3 composite cathode material for aluminum electrolysis was prepared by coldpressed sintering.The mechanical properties of the composite cathode material were measured.Its electrolytic properties were identified by a 20-A electrolysis test.Cathode samples before and after electrolysis test were measured by energy-dispersive spectroscopy(EDS).The migration behavior of various elements in the electrolysis process was studied by phase analysis.The result shows that Ni metal can effectively fill the gap between the aggregate during the sintering process,which can improve the sintering density of the composite cathode material significantly.The voltage of the 20-A electrolysis test is stable.The impurity of aluminum liquid is 0.42%.The aluminum liquid can wet the cathode surface effectively,and the Ni-TiB_2/Al_2 O_3 composite is an ideal wettable cathode material.In the process of electrolysis,the alkali elements in the electrolyte penetrate the electrode,where K goes deeper than Na.Al generated on the cathode surface will also penetrate the cathode through the gap of the composite material,while Ni in the electrode will spread into the aluminum liquid layer.     

A study of arc stability of basic electrode in view of uniform design method

In order to develop a basic electrode with low fume and good usability, a uew slag system has been designed after analyzing several basic electrode slag systems. Then in view of uniform design method, arranging the experiment points by it, the influenced laws of the uew system coating compouents on the arc stability had been searched. In the formula, niue coating compouents were taken as independent variables and they were divided into six levels in all twenty-four experiments. The arc stability was taken as function and taken down the data when welding and then put them into the computer to be processed statistically. The analysis results give the mathematical model and trend diagrams between independent variables and the function. They indicate that the effects of many coating compouents on the arc stability are in the mutual form. The mutual effects between CaCO3 and BaF2, BaF2 and BaCO3 , increases the arc stability separately. While the mutual effects between CaF2 and iron powder, the square item of iron powder itself decreases the arc stability separately.     

Preparation of Al-Sr Master Alloy in Aluminum Electrolysis Cell

1 ＩｎｔｒｏｄｕｃｔｉｏｎＡｌ Ｓｒｍａｓｔｅｒａｌｌｏｙｉｓａｋｉｎｄｏｆｍｏｄｉ ｆｉｅｒｓｕｎｄｅｒｄｅｖｅｌｏｐｍｅｎｔ .Ｉｔｈａｓｍａｎｙａｄ ｖａｎｔａｇｅｓｏｖｅｒｏｔｈｅｒｍｏｄｉｆｉｅｒｓ .Ｉｔｓｍｏｄｉｆｙｉｎｇｂｅｈａｖｉｏｒｃａｎｌａｓｔｆｉｖｅｔｏｓｅｖｅｎｈｏｕｒｓａｎｄｆｏｒｓｅｖｅｒａｌｔｉｍｅｓ ,ａｎｄｌｉｔｔｌｅｃｏｒｒｏｓｉｏｎｉｓｏｂ ｓｅｒｖｅｄｄｕｒｉｎｇｔｈｅｍｏｄｉｆｉｃａｔｉｏｎｃｏｕｒｓｅ[1 ].Ｔｈｅｒｅｆｏｒｅ ,ｉｔｉｓｃｏｍｍｏｎｌｙｕｓｅｄｉ…     

氧化物与氟化物的加入对氯化物熔盐体系电解制备Mg-La合金的影响

以石墨坩埚为阳极,钨棒为阴极,在750℃的MgCl2-LaCl3-KCl熔盐体系中,采用恒电位电解制备Mg—La合金。研究氧化物和氟化物的加入对电解的影响,通过XRD对部分Mg-La合金产物和电解渣进行表征。随着MgO或La203在熔盐电解质中加入量的增加,电流效率和所得合金产物的质量都减小,表明MgO和La203参与电解质中的反应。在加入的氧化物质量相同的情况下,MgO与La2O3相比对电流效率和合金产物质量的影响更明显。XRD研究结果表明：MgO或La2O3加入到熔盐电解质中后,有LaOCl生成,LaOCl电解渣的生成是氧化物对电解消极影响的主要原因。在本实验的的熔盐体系中,CaF2的加入对消除MgO的负面影响没有积极意义,这可能和镧化合物在熔盐电解质中的复杂反应有关。