Thermodynamic properties and mixing thermodynamic parameters of Ba-Al, Mg-Al, Sr-Al and Cu-Al metallic melts

Application of equations of mixing thermodynamic parameters formulated on the basis of the coexistence theory of metallic melts in Ba-Al, Mg-Al, Sr-Al and Cu-Al melts leads to fruitful results that not only the evaluated mass action concentrations agree well with the measured activities, but also the calculated mixing thermodynamic parameters are quite coincident with the experimental values. Moreover, the calculated mass action concentrations strictly obey the mass action law. The evaluated mixing thermodynamic parameters have very fine regularity: the mixing free energy is composed of standard free formation energies of all compounds and chemical potentials of all structural units at equilibrium; the mixing enthalpy consists of standard formation enthalpies of all compounds; the mixing entropy is composed of standard entropies of all compounds and configuration entropies of all structural units at equilibrium. As the equations of mixing thermodynamic parameters formulated are widely applicable to metallic melts involving compound formation, they can be used as the second practical criterion to determine whether thermodynamic models of metallic melts are correctly formulated.     

Relationships between Pitzer's ion interaction coefficients and ionic parameters of electrolyte solutions

1　INTRODUCTIONConcentratedelectrolytesolutionsarecommonintermediatematerialsinhydrometallurgicalandchemicalindustrialprocesses[1] .Andtheactivityco efficientisoneofthebasicpropertiesofelectrolyteso lutions ,whichisusefulfortheestimationofthesolu bilityofinorganicsalts ,thedistributionandsepara tioncoefficientsinliquid liquidextractionprocesses ,andthephasediagramofwater saltsystems .Asemi empiricalion ioninteractionmodel,alsothemostpopularmethodsofar ,proposedbyPitzer[2 ] ,canbeusedtocal…     

Microgrinding of deep micro grooves with high table reversal speed

Recent progress in the miniaturization of electronic items introduces manufacturing challenges for achieving both better surface integrity and high throughput. Controlled thermal interaction processes physically vaporize the material for producing the miniature components but the poor surface and sub-surface characteristics introduce a niche for thermo-mechanical processes, particularly microgrinding. Prior microgrinding attempts have focussed on axi-symmetrical components of hard-brittle materials. For non-axi-symmetrical, high-aspect ratio miniature components, edge chipping was encountered. This paper reports a new grinding method that uses “high table reversal speeds” for reducing the “grit cut load” and hence facilitates the microgrinding process. An arrangement that functions on the principles of four bar linkage with a sliding and rotating pair was devised. This arrangement was designed to reciprocate between 300–1000 strokes/min for a stroke length of 10–70 mm. As a result the table feed rate range was increased from the conventional 300–20 000 mm/min to 5000–55 000 mm/min.Process characterization of the new grinding method was observed for hard-brittle materials. A physical model was developed which links the process parameters with appropriate boundary conditions and the model was verified experimentally. The experimental model was used to explain the mechanism of grinding while employing high table reversal speeds. Process characterization includes grinding force, grinding-ratio, grinding wheel topography, surface finish and SEM study. Also, the process was applied to produce mold-insert which in turn was used for molding the micro-mechanical cantilever sensor parts. Deep slots of size: 1.2×0.1×1.5 mm with an aspect ratio of 15 was successfully produced with this method. The new grinding device and method promote microgrinding through integration to an existing grinder and therefore reduces the additional cost on the capital resources.     

Schiff bases of ethylenediamine as corrosion inhibitors of zinc in sulphuric acid

The work described here deals with the performance of ethylenediamine N,N^′-dibenzylidene, ethylenediamine N,N^′-di(p-methoxybenzylidene), ethylenediamine N,N^′-disalicylidene as corrosion inhibitors for zinc in sulphuric acid. The effect of various parameters on the efficiency of these inhibitors has been studied. Ethylenediamine N,N^′-di(p-methoxybenzylidene) and ethylenediamine N,N^′-disalicylidene give 99% protection under a variety of conditions. Activation energies in the presence and absence of inhibitors have been calculated. It appears that an efficient inhibitor is characterized by a relatively greater decrease in free energy of adsorption, relatively lower entropy of adsorption and relatively lower heat of adsorption. Galvanostatic polarisation studies indicate that these are basically cathodic inhibitors. Cathodic protection in the presence of these inhibitors has been studied. With an efficient inhibitor, cathodic protection is achieved at potentials much less negative than that required for plain acid. The difference between protective potential and corrosion potential appears to be less for an effective inhibitor. Mechanism of the action of inhibitors has been provided.     

页岩油加氢裂化生产柴油的研究

采用加氢精制和加氢裂化技术对w(硫)=0.5 %、w(氮)=1.2 %,w(芳烃)=32 %的页岩油进行加氢改质,160～370 ℃柴油馏分性质满足GB252-2000柴油质量标准,收率达59 %～60 %.     

掺铁氧体和SiC纤维水泥基复合材料的吸波性能

用溶胶凝胶法制备了W型Ba(Zn1-χCoχ)2Fe16O27六方铁氧体,并以铁氧体和短切SiC纤维与水泥复合,制备了水泥基复合材料.测量了该材料的电磁参数,并计算了该材料对电磁波的反射率.结果表明:χ为0.8时,W型Ba(Zn1-χCoχ)2Fe16O27六方铁氧体的吸波性能最好,该铁氧体的掺量(质量分数)为35%和短切SiC纤维掺量(质量分数)为0.2%时,水泥基复合材料在12～18GHz范围内具有最大反射率-13.5dB,有效带宽达到4.7GHz.     

电极制备工艺及电解液对LiFePO4正极材料性能的影响

利用正交实验L33(9)探讨磷酸铁锂正极的制备工艺对不同倍率下电极工作性能的影响,并对电解液的匹配性进行研究.采用不同活性物质、导电剂和粘结剂配比制成磷酸铁锂正极,应用不同电解液组装成锂离子电池,选用17mA·g-1和170 mA·g-1的工作电流密度对电池进行充放电循环测试.研究结果表明,在17mA·-1倍率充放电条件下,最佳电极制备工艺是:活性物质、导电剂和粘结剂的质量百分比为85∶7∶8,匹配的电解液为LiPF6/EC-DEC-DMC(体积比1∶1∶1,浓度1mol·L-1);在170 mA·g-1倍率充放电条件下,活性物质、导电剂和粘结剂的最佳质量百分比为80∶12∶8,与其相匹配的电解液为LiPF6/EC-DMC(体积比1∶1,浓度1 mol·L-1).     

工艺参数对微区沉淀法制备纳米MgAl2O4粉体的影响

采用高分子网络微区沉淀法制备纳米镁铝尖晶石（MgAl2O4）粉体，并采用TGA／DTA、XRD和TEM等分析测试技术对前驱体的热分解和所制得粉体的物相组成、形貌及颗粒尺寸进行表征，结果表明所制得的MgAl2O4粉体颗粒粒径小，结晶良好，成分单一且粒径大小均匀。而实验过程中工艺参数的改变会对生成粉体的粒径和形貌产生一定的影响，进而即研究了各种工艺参数的改变对该方法制备纳米MgAl2O4粉体的影响。     

复杂螺旋曲面加工刀具参数的优化设计

在螺旋曲面铣削加工过程中,刀具参数对所形成的螺旋面精度有很大的影响,为了满足其精度的需要,文章针对双螺杆混输泵转子截面廓形的几何特点,依据空间圆弧逼近原理,对转子螺旋曲面的加工刀具进行了参数优化设计,并通过计算实例验证了该优化方法的可行性。     

搅拌工艺对半固态Y112铝合金组织及性能的影响

采用自行研制的机械搅拌装置,研究了不同工艺参数对半固态Y112铝合金组织及性能的影响.研究表明,搅拌温度越高,搅拌速度越大,固相颗粒越细小、均匀和圆整,其抗拉强度与伸长率越高;但温度太高,固相颗粒会熔化,抗拉强度及伸长率也降低;随搅拌时间的延长,固相颗粒先变得细小、均匀和圆整,然后长大,抗拉强度、伸长率先升高后降低.