氟磷石灰石对熟料硅酸盐相形成过程的影响

利用XRD和化学分析方法研究了Ca5(PO4)3F的稳定性和石灰石中的Ca5(PO4)3F对C3S和C2S形成过程的影响.结果表明,Ca5(PO4)3F在1450℃下能稳定存在,1450℃时SiO2和C2S能使Ca5(PO4)3F分解;用含磷石灰石制备C2S和C3S时,1100℃和1200℃煅烧时生成β-C2S,1300 ℃煅烧时Ca5(PO4)3F分解形成的PO;-与β-C2S生成α:C2 S-xC3P,β-C2S与CaO生成C3S.在1450℃保温4h,用含磷石灰石制备的C2S全部转换为α:C2S-xC3P的固溶体.当煅烧温度由1100℃逐渐升至1450℃时,含磷石灰石中的氟随着煅烧温度的升高逐渐减少,Ca5(PO4)3F随着煅烧温度的升高逐渐分解,含磷石灰石-SiO2体系(C/S =2:1)和含磷石灰石-SiO2体系(C/s=3:1)在1450 ℃煅烧0.5h后Ca5(PO4)3F分别分解了94.00％和81.25％.     

Effects of crystal field on photoluminescence properties of Ca2Al2SiO7:Eu2+ phosphors

A series of single-phased Ca₂Al₂SiO₇:Eu²⁺ phosphors were synthesized by the solid-state reaction. Their structure and photolumi-nescence properties were investigated by the X-ray powder diffraction （XRD） and excitation and emission spectra in detail. The emission spectra of Ca₂Al₂SiO₇:Eu²⁺ phosphors consisted of blue and green band located at419 and542 nm, respectively. The relative intensities of the blue and green emission changed with Eu²⁺ concentration and were sensitive to the excitation wavelength. The unique photoluminescence property originated from the 4f⁷→4f⁶5d transition of Eu²+ at different energy levels, on which the effect of the crystal field strength was con-sidered to be tailed by adjusting the host composition.     

热电Ca3Co4O9薄膜的一致取向生长及其激光感生电压效应

利用脉冲激光沉积(PLD)法,在蓝宝石(0001)平衬底上成功制备了c轴一致取向的Ca3Co4O9薄膜。利用X射线衍射(XRD)分析测定了薄膜的相结构和生长取向。研究了不同衬底温度与不同原位氧压对Ca3Co4O9薄膜结晶质量与生长取向的影响,确定了最佳生长条件。利用这一条件在倾斜Al2O3(0001)衬底上制备了Ca3Co4O9薄膜。研究发现,当Ca3Co4O9薄膜被波长248nm,脉冲宽度20ns的脉冲激光照射时,在薄膜两端存在较大的激光感生热电电压(LITV)信号,峰值电压达到4.4V,其上升沿为36ns,半峰全宽(FWHM)为131ns。可以认为这种激光感生热电电压信号是由于Ca3Co4O9薄膜面内与面间泽贝克(Seebeck)系数张量的各向异性引起的。     

Structural studies on Ca3Al4MgO10 (C3A2M)—A ternary phase in the system CaO–Al2O3–MgO

In a sequence of temperature-dependent solid-state reactions in the system CaO–Al₂O₃–MgO the formation of the ternary phase Ca₃Al₄MgO₁₀ or C₃A₂M has been studied. Whereas the compound could not be prepared at 1200°C, a yield of 85 wt.-% of Ca₃Al₄MgO₁₀ was obtained at 1320°C (incongruent melting point: 1330°C). Powder diffraction data compare well with results of previous investigations from the 1960s. Single crystals of Ca₃Al₄MgO₁₀ could be retrieved from the sinter-pellets. Basic crystallographic data are as follows: orthorhombic symmetry, space group Pbcm, a = 5.14073(8), b = 16.7576(2), c = 10.70977(16) Å, V = 922.61(2) ų, Z = 4. Using synchrotron diffraction data it was possible to solve the crystal structure. Least-squares refinements resulted in a residual of R(|F|) = 0.021 for 1000 independent observed reflections with I > 2σ(I) and 97 parameters. The structure contains [TO₄]-tetrahedra (T=Al,Mg) forming a three-dimensional (3-D) framework whose topological characteristics have been determined. Al-Mg distributions on the different T-sites have been studied. The calcium cations are located in voids of the network. More than 50 years after its first observation our investigation clarifies the crystal structure of a compound belonging to a system that is of relevance for several fields of materials science.     

Improvement in hydration resistance of CaO granules by addition of Zr(OH)4 and Al(OH)3

Improving the hydration resistance of CaO aggregates is the key to successful application of lime-based refractories in metallurgical industry. Additive Zr(OH)₄ and Al(OH)₃ were introduced in the preparation of CaO granules using granulation equipment and calcination method in this study. The results showed that the hydration resistance of CaO granules was improved significantly, especially for granules with 0.6 wt.% Zr(OH)₄ and 0.9 wt.% Al(OH)₃, respectively. The shell of CaO granules was relatively dense after calcination and the volume of open pores of CaO granules decreased from 3.56 × 10⁻² to 1.80 × 10⁻² cm³/g when additive was introduced. Zr(OH)₄ and Al(OH)₃ have the opposite effect on the closed porosity of CaO granules, the closed porosity of CaO granules was decreased with Zr(OH)₄ addition, but increased with Al(OH)₃ addition.     

Pore-scale simulation of water/oil displacement in a water-wet channel

Water/oil flow characteristics in a water-wet capillary were simulated at the pore scale to increase our understanding on immiscible flow and enhanced oil recovery. Volume of fluid method was used to capture the interface between oil and water and a pore-throat connecting structure was established to investigate the effects of viscosity, interfacial tension (IFT) and capillary number (Ca). The results show that during a water displacement process, an initial continuous oil phase can be snapped off in the water-wet pore due to the capillary effect. By altering the viscosity of the displacing fluid and the IFT between the wetting and non-wetting phases, the snapped-off phenomenon can be eliminated or reduced during the displacement. A stable displacement can be obtained under high Ca number conditions. Different displacement effects can be obtained at the same Ca number due to its significant influence on the flow state, i.e., snapped-off flow, transient flow and stable flow, and ultralow IFT alone would not ensure a very high recovery rate due to the fingering flow occurrence. A flow chart relating flow states and the corresponding oil recovery factor is established.     

Ca^2＋对AKD施胶及CPAM助留助滤性能的影响与控制

研究了系统中的多价金属离子(如Ca2+)对AKD施胶以及CPAM助留助滤性能的影响与控制方法.研究发现.ACS能络合Ca2+等多价金属阳离子,清洁纸浆纤维表面.保护CPAM助留助滤及AKD施胶性能.在Ca2+浓度为18.75 mmol/L(相应的电导率为3000 μS/cm左右)、CS用量1.0%、AKD用量0.2%、CPAM用量0.025%及pH值7.5的条件下,加入用量为0.2%的ACS后纸料的滤水时间、自水浊度及AKD施胶度均能获得较好结果.     

臭氧多脱副产物亚硝酸钙的复盐沉淀试验研究

针对复盐沉淀法(氢氧化钙与亚硝酸钙反应生成复盐沉淀)处理烟气中臭氧氧化氮氧化物的液相吸收产物亚硝酸钙,采用控制变量法对此反应的诸多影响因素(反应温度、反应物浓度、反应过程扰动和反应物形态等)进行了试验研究.结果表明:为提高复盐沉淀效率,需要选择合适的反应温度(80℃最佳),同时反应物投药量的增加以及反应过程湍流度的增大都能够有效提高复盐共沉淀效率.复盐沉淀会伴随着氢氧化钙的析出而动态产生,构建氢氧化钙的析出条件能提高亚硝酸钙捕集效率.     

不同类型紫色土交换性钙镁含量及对烟叶钙镁分布的影响

为探讨江西紫色土交换性钙、镁含量及对烟叶钙、镁含量分布的影响,于2009年在江西紫色土烟区点对点采集土样和烟样进行了化验分析。结果表明,江西紫色土交换性钙含量丰富但变异较大,交换性镁含量偏低且交换性钙、镁比值较大,导致烟叶含钙量变异较大且烟叶含镁量较低;烟叶含镁量为中性紫色土>酸性紫色土>碱性紫色土;中性紫色土烤烟不同叶位烟叶含钙、镁量差异不大,但碱性与酸性紫色土烤烟均为上部烟叶含钙、镁量高于中下部叶;土壤交换性钙、镁之间呈极显著正相关,交换性钙、镁与土壤pH、有机质和氮、磷、钾、硫之间具有一定的相关性,但交换性钙与微量元素呈极显著负相关。     

钙离子浓度对活性污泥处理系统脱氮效果的影响

考察了钙离子浓度对活性污泥系统脱氮效果的影响。在单级序批式反应器(SBR)中,对于化学需氧量(COD)为680 mg/L、氨氮(NH⁺₄-N)质量浓度为20 mg/L的自配废水,逐步增加钙离子浓度,测定了在不同钙离子浓度下的总氮(TN)去除率、NH⁺₄-N去除率、亚硝酸氮(NO^-₂-N)和硝酸氮(NO^-₃-N)累积量及污泥体积指数(SVI),并采用最大或然数(MPN)法测得亚硝酸菌、硝酸菌和反硝化菌数量的变化规律。结果表明,在钙离子质量浓度为480~1000 mg/L时,SVI为25 mL/g,污泥颗粒密实度较大,系统中硝酸菌与反硝化菌的数量均维持在10⁴~10⁵数量级,TN和NH⁺₄-N去除率均在90%以上,NO^-₃-N累积量小于0.25 mg/L,实现了同步硝化反硝化(SND)作用,这是实现较高脱氮效果的主要原因。