氮(空气)中氢气体标准物质的研制

采用称量法制备了氮(空气)中氢气体标准物质,采用气相色谱法进行了均匀性、稳定性考察并进行了比对分析。结果表明用称量法制备的浓度范围为10×10-6~98×10-2(mol/mol)的氮(空气)中氢气体标准物质均匀性良好,稳定性可靠,符合气体标准物质制备的要求。该气体标准物质相对扩展不确定度为2%。     

氮(空气)中二氧化硫气体标准物质的研制

采用称量法制备了氮(空气)中二氧化硫气体标准物质,采用化学法进行均匀性、稳定性考察并进行了比对分析。结果表明用称量法制备的浓度范围为1×10-6~10×10-2(mol/mol)的氮(空气)中二氧化硫气体标准物质其均匀性良好,稳定性可靠,符合气体标准物质制备的要求。该气体标准物质相对扩展不确定度为2%。     

称量法制备1μmol/mol氮中微量氧气体标准物质的质量控制

依据ISO 6142和GB/T 5274标准,采用称量法制备1 μmol/mol的氮中微量氧气体标准物质.使用钢瓶清洗系统和配气系统,通过超纯气体纯化器对高纯氮中的氧杂质进行脱除,使纯化后氧含量小于3 nmol/mol.同时平行配制模拟气,确保空气中的氧对所制备的标准物质污染最小.用微量氧分析仪考察标准物质随贮存时间和压力变化的稳定性,并通过比对验证了标准物质的定值结果和不确定度,证明了该制备方法可行,定值准确可靠.气体标准物质定值扩展不确定度为2%,有效期限为12个月.     

氮中氧气体标准物质研制方法

介绍了生产国家二级氮中氧气体标准物质的制备实验方法和结果,考核了制备整个过程中进行均匀性和稳定性,给出标准物质的考核采取气相色谱分析比对方法和条件,对氮中氧气体标准物质不确定度进行了评价.     

采用比较法研制二级气体标准物质

以氮中二氧化碳二级气体标准物质的研制为例,探讨采用比较法研制二级气体标准物质及其不确定度的分析计算,其中标准物质的制备采用称量法配制,并对所研制的样品进行了均匀性、稳定性试验,结果表明,所研制的氮中二氧化碳气体的标准物质在一年的考察期内,其均匀性、稳定性、量值不确定度均达到国家二级标准物质要求,符合申报条件。     

汽车尾气监测用气体标准物质的研制

根据欧洲Ⅵ号标准,研制出低浓度汽车尾气监测用气体标准物质.该标准物质采用GB/T 5274-2008《气体分析校准用混合气体的制备称量法》中规定的方法制备并计算定值,采用气相色谱和氮氧化物分析仪对标准气体的均匀性和稳定性进行了考察,并对称量法制备过程的不确定度进行了分析评价.所制备的汽车尾气监测用气体标准物质与标准样品进行了比对,从而确保了所研制气体标准物质的量值准确可靠.     

瓶装氮气中22组分挥发性卤代烃混合气体标准物质的研制

介绍瓶装1μmol/mol氮气中22组分挥发性卤代烃混合气体标准物质的研制过程。以22种挥发性卤代烃高纯试剂为原料,采用称量法制备并计算定值,评定制备过程引入的不确定度、以及均匀性和稳定性引入的不确定度,并将研制的标准物质送至中国计量科学研究院进行测试比对,采用En值评定比对结果,结果显示En值均1,所有组分比对结果判定均为满意,验证研制标物定值结果的准确性。该气体标准物质获得国家二级气体标准物质证书,编号为GBW(E)062232,其定值的相对扩展不确定度为U=5.0%(k=2),有效期限为12个月。     

校准用溶液标准物质的量值不确定度评定

ISO导则35《标准物质定值及通用统计学原则》中要求,采取称量法制备、定值的标准物质,需评估由称量法制备、均匀性、稳定性及核验四个分量引入的不确定度.对于称量法制备的校准用溶液标准物质,制备过程中由天平和容量器具引入的不确定度往往较小且易于评估,而制备过程中其它来源不确定度以及核验、均匀性、稳定性不确定度的评估方法会对该类标准物质的总体量值不确定度水平产生显著影响.本文以导则35及GUM原则为基础,提出了针对该类标准物质量值不确定度评定的新型改进方法,以达到既确保评估的全面性,又通过适当的方案设计,去除各不确定度分量中的交叉重叠成分,避免不确定度评定结果盲目扩大的目的.     

高纯氦气中杂质标准物质的研制

介绍了重量法研制高纯氦气中微量氢气、氖气、氧气、氩气、氮气、甲烷、一氧化碳和二氧化碳8种杂质标准物质的过程,包括重量法制备技术、稀释气中相关杂质的定量及稳定性考察等。研制的8种微量气体标准物质的种类和摩尔分数参照国标GB/T 4844-2011中对高纯氦气的规定,摩尔分数范围在0.5~4.0μmol/mol之间,扩展不确定度为1%~3%（k=2）。通过参加CCQM相关国际关键比对,验证了标准物质量值的准确度。与现有的国家二级标准物质相比,研制的标准物质在种类和不确定度方面都已达到了较高水平。     

NO2气体标准物质的研制

介绍了钢瓶装NO2气体标准物质的研制过程.混合气是通过将一氧化氮、氧气和氮气充装到钢瓶中制备而成,研究了钢瓶种类、气瓶内压力和保存时间对混合气稳定性的影响.结果显示浓度低时的长期稳定性导致的不确定度大于浓度高时的长期稳定性导致的不确定度的贡献.对称量法配气和稳定性导致的不确定度,以及由于化学反应所产生的不确定度进行了评价.利用称量法制备的钢瓶装NO2气体标准物质的相对扩展不确定度不大于2%.     

Mechanism of in situ formation of AlN in Al melt using nitrogen gas

In situ processing of AlN particle reinforced aluminum composites was investigated using a gas bubbling method with nitrogen gas as the gaseous precursor and pure aluminum as the starting matrix in the temperature range of 1173–1573 K. The products were characterized using XRD, SEM, and EDS techniques. Experimental results showed that it is feasible to synthesize AlN particle reinforced Al composites in situ using purified nitrogen gas. Significant AlN was synthesized by bubbling deoxidized N₂ through Al melt. The AlN particles synthesized in situ were small in size (<10 m) and were enriched in the top part of the product formed in the crucible. Directly bubbling commercial purity nitrogen gas did not lead to formation of significant AlN due to the deleterious effect of the trace oxygen impurities in the bubbling gas. The deleterious effect of trace oxygen impurities on the mechanism of formation of AlN in the Al-N system was critically analyzed from both thermodynamic and kinetic points of view. Chemisorption of O₂ molecules at the gas bubble-Al melt interface is more favorable and much faster than that of N₂, thereby inhibiting chemisorption of N₂ molecules. Significant AlN can be formed only at the content of oxygen below a critical value in the N₂ bubbling gas.     

热分解露点法测量超纯氨中的痕量水分

介绍了运用热分解露点法测量超纯氨气中微量水分的方法与设备。主要包括SH-7000冷镜式露点仪与热分解露点检测装置(TDDP)两部分。SH-7000露点仪基于冷镜式露点仪原理,采用微型专用制冷机,可准确地测量高纯气体的露点。TDDP系统基于氨气在高温环境下通过催化剂会发生不可逆的分解反应,而氨气中微量水分不会变化的原理,配合微量氧含量的测量,可准确得到氨气中的微水分含量。     

Utilization of Deaeration via Gas Permeation and Oxidative Stabilization of Pyrogallol

The rates of oxidative decomposition for pyrogallol were determined at 3.0° in vehicles which had been prepared by passing deionized distilled water through a gas permeator. The vehicles prepared by gas permeation possessed varying dissolved oxygen concentrations which depended upon charging pressure and the residence time of effluent. A single pass through the permeator produced vehicles possessing dissolved oxygen concentrations of 05 ppm to 0.78 ppm with respect to a normal oxygen content of 8-9 ppm. A double pass through the permeator gave only trace amounts of dissolved oxygen. i.e., 0.01-0.02 ppm and this was found to be independent of charging pressure.     

Use of ion mobility spectrometry to determine low levels of impurities in gases

The use of ion mobility spectrometry (IMS) for the determination of trace moisture and oxygen in bulk nitrogen has been explored. IMS utilizes atmospheric pressure ionization to ionize trace impurities in the sample gas. Mobility differences between trace impurity ions are exploited to separate these ions. Our results indicate that an IMS can indeed be used to detect < 1 ppb O2 and H2O in bulk nitrogen. Due to the nature of the interaction between trace moisture and oxygen, a multivariate calibration has to be used to obtain quantitative results, even at levels below 2 ppb.     

硅橡胶富氧膜材料研究进展

介绍了气体膜分离原理和常见的高分子富氧膜材料的透气分离性能,针对硅橡胶富氧膜材料近些年的改性研究进行了综述和分析,指出在高乙烯基含量硅橡胶中加入起到促进传递作用的金属钴络合物、氟元素以及小分子液晶等,能显著改善富氧膜的选择透过性。而利用超临界CO2对硅橡胶富氧膜进行溶胀改性以及在富氧膜材料中添加铁氧体制备所谓的富氧"磁化膜",有望成为未来富氧膜开发研究的一个新方向。     

HDPE/PA6共混阻隔材料的制备及研究

采用熔融挤出法制备了高密度聚乙烯(HDPE)与马来酸酐(MAH)的接枝物(HDPE-g-MAH),并用红外光谱证实了接枝反应。以此接枝物为相容剂制备HDPE/PA6共混材料。研究了PA6和相容剂用量对共混材料形态结构、力学性能及阻气性能的影响。SEM表明相容剂可以明显改善HDPE与PA6的相容性。PA6的加入显著提高了HDPE对氧气的阻隔性能。     

Synthesis of sulfur-doped carbon nanotubes from sulfur powder using chemical vapor deposition

Sulfur-doped carbon nanotubes (SCNT) with high sulfur contents have been prepared using chemical vapor deposition (CVD) from sulfur powder, acetylene gas and Fe/CaCO₃ (as catalyst). In this regard, various growth's temperatures were examined to investigate its effects on the structure and the sulfur content of prepared SCNT. The best condition was obtained at 700°C and using 4 g of sulfur powder. The product was characterized using FE-SEM and EDS, which showed rode-like SCNT with about 40 nm diameter and 10.75% sulfur content. Moreover, TEM, Raman and XPS analyses were employed to obtain more details related to the product. The XPS results confirmed the presence of sulfur atoms, which covalently incorporated in the carbon framework. Finally, the catalytic ability of the product in oxygen evolution reaction was examined and the results showed high stability and low oxygen production rate for this product.     

液氮纯度分析的偏差及修正

液氮纯度是液氮产品非常关键的一个技术指标.液氮纯度的在线跟踪测量是通过测量液氮中的氧含量来实现的.在多年来的液氮在线分析及液氮出库分析过程中,发现氧含量测量结果普遍偏低.本文通过理论分析及大量的实验数据,找到了数据产生偏差的原因,并给出了科学的修正办法,为以后液氮生产过程中更加有效地控制产品质量打下了基础.     

痕量一氧化氮标准物质的研制

采用重量法研制了0.100μmol/mol的痕量氮中一氧化氮气体标准物质,其扩展不确定度为10%。在稀释气纯度分析时,采用标准添加法对纯化后的高纯氮中一氧化氮进行了准确定值,解决了痕量气体标准物质定值的难题。在长期稳定性考察时发现,气瓶中痕量一氧化氮量值随时间逐渐降低,1年内量值变化范围在4%~8%之间,并根据此结果进行了因素分析。     

基于氧弹热量计测量天然气发热量标准装置及方法的研究

根据天然气能量计量的研究现状和应用需求,研究了天然气发热量测量标准装置,采用绝热式氧弹热量计测量高纯甲烷气体发热量,使测量结果通过燃烧热标准物质溯源到国际单位上。设计并研制了平衡取气装置系统,实现了燃烧前样气的采集。高纯甲烷发热量测量结果为39900 J/m3,扩展不确定度为0.6%（k=2）。