Na和电解质对阴极炭块的渗透

采用电解与非电解,加铝液与不加铝液的方法研究了钠和电解质的渗透机理。实验发现：在非电解情况下,不加入铝液,用酚酞测试法没有检测到渗透现象,加入铝液之后,铝和电解质溶解在一起,发生了化学反应,生成钠蒸气和氟化物,渗透到阴极炭块中。在电解情况下,渗透是由化学反应和电化学反应共同引起的,电化学反应引起的渗透深度要强于化学反应。无论电解与非电解,有铝液存在时的渗透深度都是随着电解质分子比的增加而加深。     

Al2O3-CaO-CaF2-MgO渣系性能的研究

对Al2O3-CaO-CaF2-MgO渣系的初晶温度、电导率以及物相组成进行了研究.研究结果表明:在该渣系中,随着MgO的含量的增加,渣系的初晶温度先降后增,当MgO的加入量为7％时值最低,初晶温度为1 497℃.该渣系中,随着MgO加入量的增加和温度的升高,渣系的电导率也随着增大,其中主要物相组成为MgAl2O4、C...     

提高KF-AlF3-Al2O3熔体中Cu-Al基阳极的耐腐蚀性

采用恒电流和动电位极化技术研究经预氧化的和未经预氧化的Cu-Al基阳极(Cu-10Al和Cu-9.8Al-2Mn)在KF-AlF₃-Al₂O₃熔体中的阳极行为。将合金在700℃下进行短时间(8 h)氧化,然后在800℃下施以0.4 A/cm²的电流密度进行1 h恒电流极化。测定扫描速率为0.01 V/s的动电位曲线。对在阳极表面冻结的熔体样品进行XRD分析,并在实验后对阳极进行SEM分析,以研究合金表面形成的氧化皮的物相。所有阳极材料的稳态电位都在2.30~2.50 V(vs Al/AlF₃)范围内。根据动电位极化获得的数据计算阳极的腐蚀速率。结果表明,经预氧化的阳极比未经预氧化的阳极具有更低的腐蚀速率。     

酸性NaF-AlF3熔盐离子结构的Raman光谱

采用紫外激光Raman光谱,在封闭样品池中研究不同分子比的酸性NaF-AlF3熔盐的离子结构。结果表明：当电解质分子比为1时,熔盐中的铝氟离子团只以AlF4-的形式存在,而对于分子比大于1的酸性电解质,熔盐中有AlF4-和AlF63-两种铝氟离子团形式;随着温度的增加,AlF63-离子团的”寿命“越来越短,而且AlF63-特征波段峰的峰位随分子比的增加而发生红移,温度对AlF4-的”寿命“影响不大。Raman光谱的定量分析表明,在测量的熔盐配重分数区间内,温度对于熔盐中各离子摩尔分数的影响不大,而且F-含量很小,当NaF的配重摩尔分数为0.60时,AlF4-的摩尔分数在0.75左右,AlF63-的摩尔分数仅约为0.25;当NaF的配重摩尔分数增至0.71时,AlF4-的摩尔分数降为0.25左右,AlF63-增为约0.75。     

Equivalent conductivity and its activation energy of NaF-AlF3 melts

Electrical conductivity of NaF-AlF3 melts was measured by continuously varying cell constant(CVCC) technique. Relationships between equivalent conductivity at 990-1 030 ℃ and temperature and composition, and relationship between equivalent conductivity activation energy and composition of the melts were then studied on the basis of two-step decomposition mechanism of AlF63-. According to the changes of molar fractions of different anions in NaF-AlF3 melts, courses of dependence of equivalent conductivity and its activation energy on composition were analyzed. The results show that the influence of temperature on equivalent conductivity of the melts is small in the researched temperature range, and equivalent conductivity increases with increasing the molar fraction of AlF3; there is a minimum point in the activation energy-composition curve when molar fraction of AlF3 is 0.29.     

发动机缸盖水路分布测试系统研制

为了全面了解发动机冷却性能,本文研制了一套冷却水套内水路分布测试系统,实验装置为设计性能优良的冷却系统、为建立设计系统数据库,以及为确定评价设计系统优劣的指标和提供实验研究的手段,研究设计了一套缸盖上水孔流量测量系统,为缸盖内流场分布的数值模拟提供更准确的边界条件并可对各缸流量分布的合理性进行评价。     

Electrochemical deposition of aluminum on W electrode from AlCl_3-NaCl melts

Electrochemical deposition of aluminum on W electrode from AlCl3-NaCl melts was studied by cyclic voltammetry and chronopotentiometry. The results show that Al ( Ⅲ) is reduced in two consecutive steps, i.e., 4Al2Cl7-+3e-→Al+7AlCl4- and then AlCl4-+3e-→Al+4Cl-. The electrochemical reaction of 4Al2Cl7-+3e-→Al+7AlCl4- is reversible. Certain nucleation overpotential is required during the deposition of aluminum on W electrode. Chronopotentiometry analysis also shows that Al (Ⅲ ) is reduced in two consecutive steps under certain current density, which is in reasonable agreement with cyclic voltammograms. By using constant current deposition, the electrodeposits on Al substrate obtained at between 50 and 100 mA/cm2 are quite dense and well adherent to the Al substrate. The electrochemical deposition of aluminum on Cu substrate in AlCl3-NaCl melts indicates that the intermetallic compounds are formed. The intermetallic compounds are AlCu and Al2Cu.     

Identification of structural entities in NdF3-LiF melts with cryoscopic method

Nd-F species in NdF3-LiF melts were studied using cryoscopic method.Liquidus temperatures of melts of various compositions were determined by differential thermal analysis(DTA).Based on the different model calculations,NdF4- was identified as the most likely Nd-F entity in the melts in which the mole fraction of NdF3 was lower than 20%,considering only one single Nd species in the melt,and which was formed in accordance with Temkin model or Flood model.Then,activities of different components in the melts were researched.The results show that activity of LiF decreases,and that of NdF3 increases with increasing the mole fraction of NdF3.The value of activity coefficient of NdF3 is higher than 1,and that of LiF is lower than 1.     

电极材料对铝电解阴极过程研究的影响

电解铝工业中铝的析出发生在阴极上,研究铝析出反应的机理对实际工况有很好的指导意义。研究发现,炭电极上的Al、Na共沉积现象严重,致使循环伏安曲线上Al的析出峰被掩盖。因此人们试图用一些金属电极Ni、Pt、Au、Ta、Cu、W等来代替炭电极,但研究发现大部分金属电极都与Al反应生成合金,干扰了对真实电极过程的研究。只有W与Al的合金化作用较小,因此对冰晶石一氧化铝熔体的阴极电化学研究采用了W电极。而目前TiH2基可湿润阴极是极具发展前景的铝电解槽阴极材料,但这方面的研究还很不够,需做进一步的研究。     

铝电解开槽阳极技术的基础研究与工业试验

阳极开槽技术是降低铝电解气泡压降、节能降耗的有效手段。本文从实验室高温透明电解槽技术,计算流体力学(CFD)数值模拟技术和工业生产试验三个层面研究了阳极开槽对气泡行为、电解质流动、氧化铝下料位置的选取和在工业试验中的影响,并对工业试验中遇到的问题和原因进行了分析。