由精制松香催化聚合制备二聚松香的研究

以SO24-/ZrO2、SO24-/TiO2、SO24-/ZnCl2为催化剂,采用精制松香为原料催化聚合制备二聚松香,利用色谱法分析二聚松香的含量.结果表明:最宜采用SO24-/ZnCl2作催化剂,其中n(H2SO4)∶n(ZnCl2)=0.6.在松香与溶剂质量比为1:1、SO24-/ZnCl2的用量为10%(m/m)、搅拌强度为800 rpm、120℃保温聚合反应10 h和270℃减压蒸馏(200 Pa)的条件下,制备了符合ZBB 72088-89规定的一级二聚松香:含量92%,软化点182℃,酸值150.6 mg KOH/g,收率≥74%;二级二聚松香:含量≥65.5%,软化点135℃,酸值157 mg KOH/g,收率≥95%.     

离子色谱法测定柠檬黄中Cl-和SO_4（2-）离子的含量

建立了测定柠檬黄中Cl-和SO2-4含量的检测方法。用离子色谱对样品中的Cl-和SO2-4进行分离,用电导检测器检测,用峰面积外标法进行定量。柠檬黄中Cl-的检出限为6 mg/kg,SO2-4的检出限为15 mg/kg,方法的精密度高,线性关系良好,相对标准偏差小于2%。     

不同前处理条件对水产品中总砷含量的影响

比对本实验室探索的水产品试样前处理方法和国标GB/T5009.11-2003,《食品中总砷和无机砷测定》中氢化物原子荧光法前处理法的检测结果,探讨建立水产品中总砷含量测定的前处理方法。采用湿法消解,微波消解以及加入H2SO4和加入H2SO4、HCLO4进一步加热回流的微波-湿法消解处理方法,在优化条件下,比对表明只有最后一种前处理方法其检测结果满意,其准确度为100.4%,回收率为98.5%,结果的相对标准偏差为1.3%～2.5%。     

脉冲熔融-热导法测定钕铁硼中氮

钕铁硼中氮的单一测定没有标准方法和相应的参考物质,本文采用钢铁材料氮参考物质建立校准曲线,采用镍篮助熔和自动分析模式测定,建立了脉冲熔融-热导法测定钕铁硼中氮的分析方法。对比了坩埚类型、称样量、熔融功率、样品状态等分析条件对实验结果的影响。结果表明,采用高纯石墨套坩埚、0.1 g样品、熔融功率5.0 kW时,钕铁硼中氮释放完全、测试结果稳定。将本方法用于2种钕铁硼样品中氮的测定,相对标准偏差分别为0.85%、0.97%,加标回收率为94%～104%,且与化学法基本一致。     

魔芋精粉中SO2的测定

采用通气蒸馏法对魔芋精粉中SO2 的含量进行了测定 ,并提出了一种判断蒸馏终点的新方法 ,采用该方法来确定蒸馏终点 ,可以确保样品中的SO2 被完全测定。该方法还可用于其他高吸水膨胀性样品中SO2 的测定。对实验的精密度、回收率、方法的不确定度进行了研究 ,找出了影响测定结果的各个分量 ,进行了不确定度的分析和评估 ,并按照计量技术规范JJG 10 5 9- 1999给出了标准的表示法     

离子色谱法测定地质钻探泥浆中的无机阴离子

采用高速离心分离结合0.45μm孔径滤膜抽滤技术,处理油田地质钻探泥浆样品。用背景抑制电导离子色谱法对泥浆浸取液中Cl-等主要阴离子进行分析。代表性样品中高Cl-和低SO24-两种阴离子含量分别为1656和804mg·L-1;相对标准偏差(RSD)(n=6)分别为0.52%和0.62%;回收率分别为102.2%和105.2%。与传统化学法相比,该方法具有测试简便,分析周期短、准确性高的特点。     

氢氟酸挥发法测定石英砂中二氧化硅含量方法改进

由于经典氢氟酸挥发法测石英砂中SiO2含量采用铂制器皿,使方法应用在一定程度上受到限制。选用聚四氟乙烯坩埚和瓷坩埚联合方法代替铂坩埚测定SiO2含量,测定的结果与使用铂坩埚法相符。     

紫外—可见光光谱法测定载银活性炭中的Ag~+含量

采用双硫腙萃取分光光度法分别测定用三种不同方法处理的同一载银活性炭样品。在工作波长mλax=462nm处测定,线性范围为0.5mg/L￣3.0mg/L,线性相关系数为1.00。通过比较不同方法处理的样品的Ag+含量,得出了处理和测定载银活性炭中Ag+含量的最佳方法:载银活性炭加NaCl,在镍坩埚中熔融后用浓氨水溶解,并用双硫腙萃取分光光度测定其中Ag+含量。     

硼硅玻璃中三氧化二硼的前处理方法研究

为了提高三氧化二硼检测结果准确性,降低分析成本,实现高效、准确的检测,探讨了样品前处理对检测结果的影响,介绍了硼硅玻璃包装材料利用酸碱滴定法测定三氧化二硼含量方法,分析和探讨了样品粒度、坩埚、熔融试剂、样品量等因素对检测结果的影响,通过对三氧化二硼含量测定结果比较,表明降低样品量、样品经八号药典筛处理、镍坩埚氢氧化钠熔样,可节约成本,提高工作效率和检测结果准确性。     

硫酸铈滴定法快速测定锑矿石中锑

以H2SO4-K2SO4分解样品,加入少量(NH4)2MO4O13·2H2O加速样品还原,采用次甲基蓝-甲基橙作指示剂,Ce(So4)2标准溶液作滴定剂,实现了锑矿石中锑的快速测定,此法分析速度快,RSD小于3%,测定值与标准样品推荐值比较,结果吻合.     

Effects of graphitization degree of crucible on SiC single crystal growth process

Effects of graphite crucible on mass transport and crystal growth process has been investigated in the fabrication of SiC single crystal by the seeded sublimation growth method. Different graphitization degrees of the crucibles were obtained by heat treatment at various temperatures between 2100 and 2300 °C. The crucibles were subjected to SEM and XRD in which the graphitization degree was determined quantitatively. The experimental results indicate that the graphite crucible plays an important role in the SiC crystal growth by providing carbon. High crystal growth is obtained by using the untreated crucibles (corresponding to low graphitization degree), which contributes to the reaction activity between Si and graphite of the crucible. Increasing the graphitization degree results in degradation in crystal growth, even in the graphitization of the SiC seed crystal.     

真空冶炼用MgO-CaO坩埚的研制

为了降低真空冶炼用MgO坩埚因MgO的高温不稳定性对冶炼合金造成的影响,同时发挥CaO的脱硫作用,以w(MgO CaO)>97%的MgO-CaO熟料为原料,在对MgO-CaO熟料进行水化试验和烧结试验研究的基础上,研制了MgO-CaO坩埚,并且与CaO坩埚一起对一种纯金属和同材质的高温合金进行了对比冶炼试验。结果表明:MgO-CaO熟料的抗水化性远高于石灰熟料的;在添加适当种类和数量的烧结助剂后,MgO-CaO熟料的可烧结性明显改善;MgO-CaO坩埚的冶炼效果达到甚至超过了CaO坩埚。     

CaZrO_3耐火材料的制备及其与钛合金熔体的界面反应

合成了一种CaO-ZrO_2系复合耐火材料,用模压法成型,分别在1 650℃和1 680℃烧结制成坩埚.使用此坩埚在感应炉中熔化钛合金(TiNi),在真空条件下, 1 500℃保温5min.对在1 680℃烧结成的坩埚进行了抗水化性能测试.用X射线衍射仪对CaZrO_3材料进行物相分析.用扫描电子显微镜观察钛合金与此材料的界面反应层的微观形貌,结合能谱仪进行微区成分分析.结果显示:1 680℃烧成的CaZrO_3材料具有良好的抗水化性;用此坩埚熔化TiNi合金后,液态钛合金和耐火材料的界面反应层厚度约为30μm,界面反应层中,Ca,Zr,Ti,Ni等元素无明显扩散.     

Oxidation–Reduction Equilibrium in Copper Phosphate Glass Melted in Air

Copper phosphate glasses with 40, 50, and 60 mol% CuO in batch were melted in air at 1000°, 1100°, and 1200°C using quartz or alumina crucibles, and the [Cu²⁺]/[Cu_total] ratio variations with melting time were measured. Glasses were oxidized during melting and reached equilibrium [Cu²⁺]/[Cu_total] ratios which were independent of melting temperature and identical for the 40 and 50 mol% CuO content glasses. Structural considerations seemed to have determined oxidation-reduction equilibrium rather than an equilibrium redox reaction. Also, the effects of crucible type on the oxidation-reduction balance were examined. It was found that a quartz crucible is more inert and has less effect on the oxidation-reduction equilibrium of glass than an alumina crucible. Crucible contamination and phosphorus vaporization were found to diminish as the CuO content in the batch was increased.     

Kinetics of decarburization of molten fe-c by gaseous hydrogen

Hydrogen was directed onto the surface of Fe-4%C held in an Al₂O₃ crucible at 1327°C, and the rate of formation of CH₄ was measured by mass-spectrometric analysis of the effluent. The measured rate approached the theoretical limit of mass transfer of CH₄ in the gas phase, provided that the concentration of other gases evolved by side-reactions was small. Deviations from predicted values appeared to be caused by carbon monoxide coming from the reaction of dissolved carbon with the crucible, and water coming from the reaction of hydrogen with the refractories. The gas mass transfer coefficient for the particular geometry used was determined in separate experiments where the carbon was oxidized by CO₂.     

Effect of cooling rate and alumina dissolution on the determination of temperature of critical viscosity of molten slag

In slagging gasifiers with crystalline slag, the fluctuation in temperature near the temperature of critical viscosity (T_cv) can rapidly increase the molten slag viscosity and cause an accumulation of slag inside the gasifier. In order to prevent operational problems caused by the slag, one therefore needs to obtain an accurate measurement of T_cv. The effects of cooling profile and the extent of alumina dissolution on the experimentally determined T_cv were investigated. A synthetic slag was prepared using a composition of Alaskan Usibelli ash, which exhibited crystalline slag behavior, and T_cv was determined under constant cooling and equilibrium conditions. The T_cv measured under 2°C/min of constant cooling was 33°C lower than the T_cv under equilibrium conditions. The effect of alumina dissolution was determined using a platinum (Pt) lined crucible. At a 2°C/min cooling rate, the T_cv measured using a bare alumina crucible was 23°C higher than that from the Pt-lined crucible, offsetting the difference caused by constant cooling. In order to determine a safe gasification temperature range, however, the measurement of T_cv under constant cooling conditions should be avoided.     

Slag resistance of chamotte refractories with particolored clay

A laboratory study of slag resistance of fireclay specimens on substitution for clay DN2 in the binding part of the mixture by a refractory clay is presented. The slag resistance is determined by the crucible method. It is shown that the replacement by the refractory clay for DN2 does not cause a decrease in the slag resistance of refractories of equivalent density. The results of the laboratory study have been confirmed by full-scale tests.     

Alumina/Aluminum Composites Formed by the Directed Oxidation of Aluminum Using Sodium Hydroxide as a Surface Dopant

Al₂O₃/Al composites have been formed by the directed oxidation of Al using NaOH as a surface dopant. Oxidation kinetics were monitored by thermogravimetric analysis. Product microstructures were examined using optical microscopy and scanning electron microscopy coupled with microanalysis using energy and wavelength dispersive spectroscopy. NaOH-driven directed oxidation of Al occurs in the temperature range of 850°–1200°C, and the resulting microstructure varies with different doping levels. The growth product is seen to nucleate and grow not only on the top surface of the parent Al but also along the crucible wall and even on the external surface of the crucible. The Al channel size in the product is determined by the initial surface dopant level.     

二苄叉法测定季戊四醇含量的改进

为了提高季戊四醇含量测定的准确性。二苄叉法测定季戊四醇含量方法中,沉淀的洗涤和收集至关重要,在多孔玻璃坩埚上加一层滤纸,使生成的沉淀物不能浸入多孔玻璃坩埚内,增加了结果的准确性,同时洗涤方法更方便、快捷。