Separation of red (Y2O3: Eu3+), blue (Sr, Ca, Ba)10(PO4)6Cl2: Eu2+ and green (LaPO4: Tb3+, Ce3+) rare earth phosphors by liquid/liquid extraction

A novel process for separation of red (Y₂O₃: Eu³⁺), blue (Sr, Ca, Ba)₁₀(PO₄)₆Cl₂: Eu²⁺ and green (LaPO₄: Tb³⁺, Ce³⁺) fine tricolor phosphor powders was established. First, the green phosphor was extracted and separated from three phosphor mixtures in heptane/DMF(N, N-Dimethylformamide) system using stearylamine or laurylamine (DDA) as the cationic surfactant. Then, after being treated with 99.5% ethanol, the blue and red phosphors could be separated in Heptane/DMF system in presence of 1-octanesulfonic acid sodium salt as the anionic surfactant. Satisfactory separation results have been achieved through two steps extractions with their artificial mixtures. The grades and recovery of separated products reached respectively as follows: red product was 95.3% and 90.9%, blue product was 90.0% and 95.2%, and green product was 92.2% and 91.8%. Funded by the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry (ROCS, SEM [2005] No. 383)     

Separation of red (Y2O3:Eu3+), blue (BaMgAl10O17:Eu2+) and green (CeMgAl10O17:Tb3) rare earth phosphors by liquid/liquid extraction

A novel process for separation of red (Y₂O₃:Eu³⁺), blue(BaMgAl₁₀O₁₇:Eu²⁺) and green (CeMgAl₁₀O₁₇:Tb³) rare earth fluorescent powders was proposed. At first, the blue powder can be extracted selectively from an aqueous solution using a chelating collector 2-thenoyltrifluoroacetone (TTA) dissolved in heptane at alkaline pH condition, then, chloroform was used for extracting the green powder into organic phase. The red phosphor remains in aqueous phase with potassium sodium tartrate depressant (PST). Therefore, three phosphors can be separated successfully from their artificial mixtures by liquid/liquid extraction, and grades and recovery of separated products reach respectively as follows: red is 96.9% and 95.2%, blue is 82.7% and 98.8%, green is 94.6% and 82.6%. Funded by the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry (ROCS, SEM [2005] No. 383)     

Effect of Sr(Zn1/3Nb2/3)O3 modification on the energy storage performance of BaTiO3 ceramics

Lead-free (1-x)BaTiO₃-xSr(Zn_1/3Nb_2/3)O₃ (abbreviated as BT-xSZN, x = 0–0.08) relaxor ferroelectric ceramics were prepared using the traditional solid phase technology, and the effects of SZN modification on their phase structures, microstructures, dielectric performance, ferroelectricity and energy storage performance were studied in detail. A pure perovskite phase was observed in the BT-xSZN ceramics. The BT-based ceramics modified by SZN exhibited refined grain size. As the SZN content was increased, the breakdown strength initially increased and then decreased, and the ferroelectric loops gradually became ‘slim’. The BT-xSZN (x = 0.07) ceramics demonstrated a favourable energy storage performance with high recoverable energy density (W_rec = ~1.45 J/cm³) and energy storage efficiency (η = ~83.12%) at 260 kV/cm. Results indicate that the energy storage performance of BaTiO₃ ceramics modified by SZN can be remarkably improved, widening their applications in energy storage at low temperatures.     

燃油中硫含量对颗粒物排放和气体排放的影响

着重阐述了燃油中硫含量与排放颗粒物直径和浓度的关系。通过在船用燃油(MDO)中混入二硫化物((CH3 )3CS-)2(DBDS)调整燃油中的硫含量,对柴油发动机排气进行测量和分析,对可溶性有机物质SOF(Sol-uble Organic Fraction)的浓度,非可溶性物质DS(Dray Soot)的浓度以及排放颗粒物PM的质量浓度以及颗粒物直径的分布进行了分析研究。试验结果表明:随着硫含量的增加,PM直径变小,但是质量浓度增加;SOF质量浓度和DS质量浓度增加,因此PM的质量浓度也增加;发动机的着火迟延期变短,最高燃烧压力降低,同时CO排放浓度增加,N O排放浓度降低。     

A Metal-Oxide Surge Arrester model with active V-I characteristics

Generally a model of Metal Oxide Surge Arrester (MOSA) for numerical analysis uses a nonlinear resistance. But actual Voltage-Current (V-I) characteristics of MOSA have a hysteresis loop in the time domain like the i-Φ characteristic of a transformer and frequency dependency. The authors have investigated the relation between the actual V-I hysteresis characteristics obtained by some current waveforms and the static V-I characteristics. From the voltage difference between the above two characteristics, an equation was derived and a new model of MOSA was developed. This model consists of a nonlinear resistance representing the fundamental V-I characteristic, a linear inductance, and a voltage source that depends on the absorbed energy. The calculated results by the proposed model are compared with measurement results by using the waveform of standard impulse current, steep front current, and oscillated current. The accuracy of the model has been confirmed to be satisfactory. The model is expected to be useful to investigate insulation coordination of power systems. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 121 (1): 35–42, 1997     

热浸镀锌层界面的微区电化学腐蚀行为

目的 探究钢铁热浸镀锌的镀层/钢基体界面的微区电化学特性及腐蚀行为。方法 采用扫描电化学显微镜(SECM)分析技术,研究镀层/钢基体界面在0.1 mol/L NaCl溶液腐蚀过程中微区电流的演变过程,结合扫描电镜(SEM)、能谱仪(EDS)、3D显微镜以及X射线衍射技术(XRD)等分析腐蚀产物的物相组成与分布规律。结果 在腐蚀过程中,镀锌钢的腐蚀产物主要分布在热浸镀锌层界面处靠近钢基体的一侧,在镀锌层表面的分布较少,腐蚀产物主要由Zn5(OH)8Cl2、Zn5(OH)6(CO3)2与ZnO等物相组成。在腐蚀开始阶段,钢基体区域的SECM还原电流(I=1.2)大于镀锌层(I=1.1)。随着腐蚀时间的延长,镀层/钢基体界面处的SECM还原电流整体降低,同时在界面靠近钢基体一侧存在电流凹陷区(I=1.0),表明腐蚀产物主要沉积在此处,并对镀层的腐蚀起到保护作用。此外,在腐蚀过程中氧气的消耗主要发生在钢基体区域,随着腐蚀时间的增加,镀层和钢基体表面的溶解氧含量都逐渐降低。结论 在浸泡腐蚀过程中,镀锌层作为阳极,溶解生成Zn²⁺,并向钢基体区域扩散,同时钢基体表面消耗氧气,还原形成OH^–向镀锌层区域扩散。Zn²⁺与OH^–以及溶液中其他离子结合,生成腐蚀产物,在靠近镀层/钢基体界面处的钢基体一侧沉淀,对钢基体起到一定的保护作用。     

多股钢丝帘线初始伸长的有限元评估

当拉伸一个包含多个元件的结构件时,会产生初始伸长,在许多制造过程中,初始伸长的影响显著。在轮胎生产过程中,嵌有钢丝帘线的胎坯放置到花纹模腔中进行压制,以得到相应的胎面花纹。在此过程中,橡胶中的帘线被拉伸。因此,生产过程中轮胎中的帘线会有约百分之几的初始伸长。然而,轮胎制成后,帘线不会出现初始伸长。     

LDHs对6061铝在不同溶解氧浓度的NaCl溶液中腐蚀行为的影响

通过原位合成法在6061Al合金表面制备了层状双氢氧化物（LDHs）,使用极化曲线（Tafel）和电化学阻抗谱（EIS）研究了在3.5%（质量分数）NaCl溶液中不同溶解氧浓度（1~16 mg/L）下LDHs对6061Al合金腐蚀行为的影响。结果表明,6061Al合金与LDHs/6061Al合金的极化过程均受到溶解氧的扩散控制。随着溶解氧浓度的增加,6061Al合金的腐蚀更加剧烈,其腐蚀电流由1.273 μA增加到了1.743 μA,蚀坑深度由12 μm增加到了19 μm。而LDHs/6061Al合金在各溶解氧浓度下均未观察到蚀坑,这是由于LDHs薄膜阻碍了溶解氧的扩散,其极化过程受到了抑制。此外,随着溶解氧浓度的增加,6061Al合金的阻抗显著增加,这与Al₂O₃的形成有关;而LDHs/6061Al合金的阻抗在不同溶解氧浓度下未发生明显变化,表现出对溶解氧优异的隔绝性能。     

铝热还原工艺条件对Al-Ti-Ce中间合金物相结构和合金元素浓度的影响

在Na3AlF6-NaCl-KCl氟氯混合电解质体系中,通过铝热还原法以TiO2和CeO2为Ti源和Ce源,制备Al-Ti-Ce中间合金。研究反应时间、反应温度、电解质构成（Na3AlF6质量百分含量）、K2TiF6添加量四种工艺条件对Al-Ti-Ce中间合金物相结构和合金元素浓度的影响。实验结果表明,在所有实验工艺参数范围内,制备的Al-Ti-Ce中间合金均由ɑ-Al、Al3Ti和Ti2Al20Ce三相构成。制备的最佳单因素工艺参数为：反应时间90 min,反应温度850℃,Na3AlF6质量百分含量40 %、K2TiF6添加量20 mol%。热力学分析结果从理论上进一步证明了在实验条件下几种主要化学反应的可行性。     

Study of Zinc Dialkydithiophosphate Antiwear Film Formation and Removal Processes,Part I: Experimental

The Static Stress field in and unpressurized, rounded, rectangular, elastomeric seal is examined using both experimental and numerical techniques. A particular stress separation method is successfully employed in the photoelastic study.

The salient features of the stress field and their relevance to the seal performances are outlined. An approximate theoretical model is proposed which permits the determination of the contact pressure profile.