Influence of manganese substitution into the A-site of perovskite type Ca1−xMnxTiO3 ceramic

Ca_1−xMn_xTiO₃ (x = 0–1.0) perovskite ceramics were prepared by conventional solid state reaction. XRD was used to confirm the microcrystalline nature of the Ca_1−xMn_xTiO₃ crystals. For the x = 0 composition, the XRD patterns were those of a single orthorhombic perovskite while for x = 0.2–0.8, the XRD spectra were those of two orthorhombic perovskite phases: CaTiO₃ and MnTiO₃. For x = 1, XRD pattern was that of the MnTiO₃ phase only. The morphology and particle size of the grains of the different composition were observed using SEM. The size of the particles increased from 0.2 μm to 2–3 μm as x increased from 0 to 0.6. The room temperature dielectric constant at the frequency of 110 kHz for the x = 0.2 and x = 1.0 ceramics were ∼3.41 × 10⁴ and ∼4.99 × 10³, respectively. The ESR linewidth of samples increased with increasing manganese content due to the formation of magnetic cluster. Our ESR studies indicate that the manganese ions are in the Mn⁴⁺ state.     

Effect of cocatalysts on ethylene polymerization with fluorinated bisphenoxyimine titanium as a catalyst

In this study, we examined various alkylaluminums, including triethylaluminum (TEA), triisobutylaluminum (TIBA), and diethylaluminum chloride (DEAC), as cocatalysts for the activation of ethylene polymerizations in the presence of a fluorinated Fujita group invented titanium (FI‐Ti) catalyst, bis[N‐(3‐tert‐butylsalicylidene)‐2,3,4,5,6‐pentafluoroanilinato] titanium(IV) dichloride (complex 1 ). DEAC, because of the strong Lewis acidity, was an efficient cocatalyst for activating complex 1 for the ethylene polymerizations, whereas TEA and TIBA as cocatalysts could hardly polymerize ethylene. The effects of the polymerization temperature and Al/Ti molar ratio on the formation of active species, properties, and molecular weight of the resulting polyethylene were investigated. In the complex 1 /DEAC catalyst system, the oxidation states of Ti active species were determined by electron paramagnetic resonance. The results demonstrated that Ti(IV) active species were inclined to polymerize ethylene and yielded high‐molecular‐weight polyethylene. Comparatively, Ti(III) active species resulted from the reduction of Ti(IV) by DEAC and afforded oligomers. Moreover, the bigger steric bulk for the cocatalysts was necessary to achieve ethylene living polymerization with the fluorinated FI‐Ti catalyst. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Role of choline formate ionic liquid in the polymerization of vinyl and methacrylic monomers

Polymerizations of vinyl and methacrylate monomers (2‐hydroxyethyl methacrylate, styrene, and methyl methacrylate) were carried out in a choline formate ionic liquid at room temperature without the addition of peroxide‐based initiators. Choline formate acted as both an initiator and a solvent and produced high‐molecular‐weight polymers. Gel permeation chromatography and electron paramagnetic resonance measurements indicated that the polymerizations predominantly occurred by a free‐radical mechanism. This method of polymerization provides an alternate route to eliminate the use of toxic initiators and solvents. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

基于PLC的抽锭式电渣连铸自动控制系统设计

介绍了用于抽锭式电渣连铸设备中的自动控制系统,该系统由PLC进行控制,工控机通过PC/PPI电缆与PLC通讯,进行熔铸参数的设置.通过传感器对熔铸状态进行采样、监控,实现熔铸过程的自动、平稳进行,并可对铸锭质量进行过程监控.通过实际应用,该系统运行稳定可靠.     

水电机组用超厚S550Q/Z35钢板的研制开发

通过合理的化学成分设计以及电渣重熔冶炼、轧制和热处理工艺设计,成功研制开发了280 mm超大厚度规格S550Q/Z35钢板。钢板的各项性能良好,完全可以应用于大型水轮发电机组制造。     

舞钢40 t板坯电渣炉渣系的选择与应用

主要从电渣重熔过程中熔渣的作用和性能要求出发,阐述了渣系对电渣重熔的影响,并根据生产实践,介绍了几种渣系在舞钢公司电渣炉中的应用情况,为电渣炉渣系的选择提供参考。     

舞钢板坯电渣钢锭表面渣沟现象浅析

结合舞钢板坯电渣锭的生产实际,针对生产中出现的表面渣沟现象,从熔速、渣系、锭体冷却等方面进行了简单的剖析,并采取了相应的预防措施,取得了显著的效果。     

30t～120t单电极双塔式结构三工位可交替熔炼的恒熔速保护气氛电渣炉

本电渣炉是双塔式结构三工位可交替熔炼的恒熔速保护气氛电渣炉,其特征是配有两套塔式结构的可转动炉头部分,可分别在三个工位进行交替重熔冶炼。其特征在于,结合上述特征,再通过塔式机架、可转动和升降的炉头、电极调整装置、升降烟罩气氛保护、高精度称重系统、恒熔速自动控制系统技术的采用,最终满足大吨位高质量电渣锭的生产需求。优点：解决了现有技术所存在的大吨位高质量电极生产的困难,同时,还提高了电渣炉的有效利用率和生产的灵活性,提高生产效率。     

电子自旋共振法和分光光度法测定酿酒葡萄籽原花青素抗氧化活性

利用电子自旋共振技术(ESR)对酿酒葡萄籽原花青素4个不同提取样品(GSP0、GSP1、GSP2、GSP3)抗氧化特性进行研究,并采用分光光度法进行对比分析。结果表明:电子自旋共振法和分光光度法均测得,GSP3样品对DPPH自由基清除能力最强;反应30min,质量浓度小于40mg/L时,样品质量浓度与清除率呈正相关,质量浓度大于40mg/L时,清除率趋于稳定。ESR测得的原花青素的清除率普遍高于分光光度法:反应30min,ESR测得不同质量浓度的GSP0的清除率最低为35.99%,最高为99%,而分光光度法测得分别为7.06%、78%;ESR测得的GSP3清除率最低为52.45%、最高值为99%,分光光度法测得的清除率分别是29%、95%。     

Characterization of Wood and Wood-Plastic Composite

Wood-plastic composites (WE) were prepared with low-grade wood (kadom, simul, and mango) of Bangladesh and MMA (methyl methacry-late) under Co-60 gamma irradiation with a 3-Mrad dose (800 krad/h). Polymer loading and tensile properties of the composites were determined and the effect of urea and N-vinyl pyrrolidone (NVP) on these properties was studied. The polymer loading (PL) increases slightly (2-3%) with the addition of urea to the MMA + MeOH solution: however, this increment is 616% with NVP addition and 12-54% with urea + NVP, depending on the type of wood. Similarly, the tensile strength (TS) increased by 11-25%, the bending strength (BS) by 31-48%, and the compressed strength (CS) by 40-67%. To further characterize the composite, the samples were investigated with infrared (IR), electron-spin resonance (ESR), and thermally simulated luminescence (TSL) techniques. IR studies reveal that MMA was grafted with the wood substrate; ESR and TSL investigations detected the residual free radicals (not the primary free radicals) in the composites.