Reaction process of monazite and bastnaesite mixed rare earth minerals calcined by CaO-NaCl-CaCl2

The decomposition reactions of monazite and bastnaesite mixed rare earth minerals calcined by CaO-NaCl-CaCl2 were studied by means of TG-DTA and XRD. The results show that the process of the minerals decomposed by CaO involves two steps. The first step occurs in the temperature range of 425-540 ℃, and the main reactions are bastnaesite decomposition, i.e. REOF reacts with CaO to produce RE2O3 and CaF2, and Ce2O3 is oxidized to CeO2. During this step, CaCO3 is formed at about 500 ℃. The second step takes place in the temperature range of 610-700 ℃, and the reactions are monazite decomposition into RE2O3, Ca5F（PO4）3 and Ca3（PO4）2 by CaO and CaF2. In this process, the decomposition ability is improved because CaO from CaCO3 decomposing has high chemical activity. In calcining process, the new formed Ca5F（PO4）3 restrains fluorine that can escape in form of gaseous compound. The decomposition ratio of the mixed rare earth minerals reaches 90.8% at 700 ℃.     

国外过氧化氢在化学合成中应用研究进展

介绍了近期国外过氧化氢在部分化学品合成中应用研究新进展 ,产品包括过碳酸钠、过碳酰胺、4Na2 SO4·2H2 O2 ·NaCl加合物、叔胺氧化物、水合肼、二羟基苯、季铵盐过氧化氢和甲乙酮肟。内容涉及产品质量 (纯度、安定性、溶解速率、外观等 )、产品收率、催化剂、工艺过程等方面改进。主要介绍专利技术。     

氰化亚铜生产新工艺研究

在氯化钠浓溶液中通氯气将铜氧化生成NaCuCl2，再加入氰化钠溶液生成氰化亚铜沉淀。沉淀经氯化钠浓溶液洗涤和水洗干燥后即得产品。工艺生产周期短，设备简单，成本低，产品质量高，无废气，废渣和有毒废水排放。     

Passivation and pitting corrosion of nanostructured Sn-Ni alloy in NaCl solutions

The passivation and pitting corrosion of tin-nickel alloy (34% Ni-66% Sn) in NaCl solution was studied using potentiodynamic, cyclic voltammetry and electrochemical impedance spectroscopy (EIS) techniques complemented by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The effect of concentration of the chloride ion, the switching potential, scans rate and pH on the electrochemical behavior of Sn-Ni alloy is discussed. The data indicate that the corrosion rate and the pitting corrosion of Sn-Ni alloy increases by the increasing of chloride ion concentration. The observed corrosion resistance of electrodeposited Sn-Ni alloy is due to the formation of a thin passive film from tin and nickel oxides.     

Weight loss, polarization, electrochemical impedance spectroscopy, SEM and EDX studies of the corrosion inhibition of copper in aerated NaCl solutions

This work reports results of weight loss, potentiodynamic polarization and impedance measurements on the corrosion inhibition of copper in aerated non-stirred 3% NaCl solutions in the temperature range 15–65 °C using sodium oleate (SO) as an anionic surfactant inhibitor. These studies have shown that SO is a very good ”green”, mixed-type inhibitor. The inhibition process was attributed to the formation of an adsorbed film on the metal surface that protects the metal against corrosive agents. Scanning electron microscopy (SEM) and energy dispersion X-ray (EDX) observations of the electrode surface confirmed the existence of such an adsorbed film. The inhibition efficiency increases with increasing surfactant concentration and time of immersion, while it decreases with solution temperature. Maximum inhibition efficiency of the surfactant is observed at concentrations around its critical micellar concentration (CMC). The potential of zero charge (pzc) of copper was studied by ac impedance, and the mechanism of adsorption is discussed. The sigmoidal shape of the adsorption isotherm confirms the applicability of Frumkin’s equation to describe the adsorption process. Thermodynamic functions for the adsorption process were determined.     

N-异丙基丙烯酰胺凝胶在NaCl水溶液中溶胀行为的预测研究

In this paper, a model is presented to correlate and predict the swelling behavior of hydrogels in aqueous solutions of electrolytes. The model is a combination of VERS-model, “phantom network“ theory and “free-volume“ contribution. The VERS-model is used to calculate Gibbs excess energy; “phantom network“ theory to describe the elastic properties of polymer network, and “free-volume“ contribution to account for additional difference in the size of the species. To test the model, a series of N-isopropylacrylamide based hydrogels are synthesized by free radical polymerization in oxygen-free, deionized water at 25~C under nitrogen atmosphere. Then, the degree of swelling of all investigated gels as well as the partition of the solute between the gel phase and the surrounding coexisting liquid phase are measured in aqueous solution of sodium chloride. The model test demonstrates that the swelling behavior correlated and predicted by the model agrees with the experimental data within the experimental uncertainty. The phase transition appeared in the experiment, and the influences of the total mass fraction of polymerizable materials ξgel as well as the mole fraction of the crosslinking agent YCR on the swelling behavior of IPAAm-gels can also be predicted correctly. All these show the potential of such model for correlation and prediction of the swelling behavior of hydrogels in aqueous solutions of electrolytes.     

α-烯烃磺酸盐、NaCl、NH_4Cl对液体洗涤剂粘度影响的研究

研究了阴离子表面活性剂/非离子表面活性剂复配液体洗涤剂时α 烯烃磺酸盐、NaCl、NH4Cl对其粘度的影响。结果表明:液体洗涤剂中无论是否含有NaCl或NH4Cl,其粘度均随体系中α 烯烃磺酸盐浓度的增加而下降。NaCl或NH4Cl对液体洗涤剂粘度的提高程度与α 烯烃磺酸盐的浓度有关。对以α 烯烃磺酸盐为主体表面活性剂的液体洗涤剂,其粘度的提高与NaCl或NH4Cl的浓度有关。     

活性粉末混凝土冻融循环前后NaCl溶液的吸入特性

为更好地理解混凝土盐冻破坏机理,研究了NaCl溶液中NaCl质量分数对活性粉末混凝土溶液吸入量的影响规律,并比较了试件表面及芯部吸入面溶液吸入特性的差异;分析了冻融循环1 000次对溶液吸入特性的影响,给出了不同吸入面的毛细吸液系数.研究表明:活性粉末混凝土毛细吸液量随着NaCl质量分数的增大而减小;15~180 min和180~540 min两阶段溶液吸入量均与t1/2呈线性关系;试件表面毛细吸液系数远小于芯部;冻融循环1 000次后溶液吸入量显著降低,仅为冻融循环前的0.33倍;冻融循环1 000次后距离试件表面越远的吸入面毛细吸液系数越大.     

CH4、CO2与稀有气体溶解度的估算模型及其地质应用

CH₄、CO₂、稀有气体的溶解度模型在地球科学领域应用广泛。它们的溶解度模型在研究流体包裹体的均一化压力、古气温变化、天然气运移与聚集规律、富氦天然气成藏、储层中气—水体积比等方面发挥着重要作用。主要综述了纯水与NaCl水溶液中CH₄、CO₂、稀有气体溶解度研究的新进展。重点介绍了精度高且适用性广的模型的建立过程及其适用范围,并给出了部分模型的计算结果。包括：①0~250 °C、0.1~200 MPa、0~6.0 mol/kg NaCl溶液中CH₄的溶解度模型;②0~450 °C、0.1~150 MPa、0~4.5 mol/kg NaCl溶液中CO₂的溶解度模型;③0~80 °C范围内大气稀有气体溶解度与亨利常数的计算模型;④纯水中稀有气体亨利常数计算模型;⑤0.1 MPa、0~65 °C、0~5.8 mol/kg NaCl溶液中稀有气体的溶解度模型。CH₄与CO₂的溶解度模型复杂,但精度高,适用范围广。稀有气体溶解度模型的精度相对较低,适用范围相对较小,有待进一步提高与改进。CO₂—稀有气体—水体系中,低密度的CO₂对稀有气体溶解度的影响较小,而高密度的CO₂对稀有气体的溶解度有较大的影响。目前还无法判断CH₄—CO₂—稀有气体共存时对彼此溶解度的影响程度,其混合气的溶解度模型需要加强研究。     

纳米化对Ti-48Al-8Cr-2Ag合金抗氧化和抗腐蚀性能的影响

利用磁控溅射的方法在Ti-48Al-8Cr-2Ag(at．％)合金上溅射相同成分的纳米晶涂层，以研究纳米化对Ti-48Al-8Cr-2Ag合金抗氧化和抗腐蚀性能的影响，氧化实验在800℃～1000℃进行，腐蚀试验在盐和水蒸气综合条件下进行．结果表明：900℃氧化，Ti-48Al-8Cr-2Ag涂层显示了较低的氧化速率，因为生成保护性氧化铝膜，而铸态合金则在局部区域生成TiO2 Al2O3混合氧化膜．1000℃氧化，涂层和铸态合金生成保护性Al2O3膜，均具有很好的抗氧化性能．但溅射涂层在1000℃的氧化速率高于铸态合金，因为涂层球状表面和柱状晶结构，提供了更多的有效氧化面积．在600℃～700℃，盐和水蒸汽综合作用下，TiAlCrAg合金表面形成Al2O3 TiO2混合氧化膜，显示了较差的抗腐蚀性能．溅射纳米晶涂层在局部区域生成氧化铝保护膜，抗腐蚀性能大大改善．