汽车尾气检测用气体标准样品的研制

叙述了轻型汽车污染物检测仪器使用的氮气中一氧化碳、二氧化碳、丙烷、一氧化氮气体标准样品的制备,以气相色谱法对其均匀性和稳定性进行考核,确保检测数据准确可靠。配制的标准气体的浓度为（10～500）×10^-6（mol／mol）。     

氮中微量氧气体标准物质分析方法和定值方法的研究（下）

介绍了氮中微量氧标准气体的分析方法,给出了分析条件和方法的精密度,并对该标准气体配制的均匀性、稳定性的实验结果进行了分析与考察,对该气体标准物质的性能进行了评价。氧含量在(2~10)μmol/mol浓度范围气体标准物质定值不确定度<±2%;氧含量在(20~100)μmol/mol浓度范围气体标准物质定值不确定度<±1%,取得了国际的等效性。     

氮中微量氧气体标准物质分析方法和定值方法的研究 (上)

介绍了氮中微量氧标准气体的分析方法,给出了分析条件和方法的精密度,并对该标准气体配制的均匀性、稳定性的实验结果进行了分析与考察,对该气体标准物质的性能进行了评价。氧含量在(2~10)μmol/mol浓度范围气体标准物质定值不确定度<±2%;氧含量在(20~100)μmol/mol浓度范围气体标准物质定值不确定度<±1%,取得了国际的等效性。     

氮中一氧化碳气体标准物质的研制

介绍了氮中一氧化碳气体标准物质的研制过程。以高纯一氧化碳气体、高纯氮气为原料,采用称量法制备了浓度为100、500、1 000μmol/mol、0.5%mol/mol的氮中一氧化碳气体标准物质,采用与国家一级标准物质比较的方法定值。对原料气中的杂质进行了分析,对制备的气体标准物质进行了均匀性和稳定性评估。结果表明：研制的氮中一氧化碳气体标准物质均匀性和稳定性良好,标准值为100、500、1 000μmol/mol、0.5%mol/mol(U_r=2%k=2)。     

称量法制备气体标准物质的称量相对标准不确定度评定方法研究

结合国际称量法制备气体标准物质的标准ISO 6142,提出以质量比较仪为称量工具,制备二元混合气体标准物质和多元混合气体标准物质的称量相对标准不确定度的评定方式。并以称量法制备10μmol/mol氮中一氧化氮气体标准物质为例,比较两种方式的评定结果,表明所提出的两种不确定评定方式比国际标准ISO 6142中使用机械天平的称量相对标准不确定评定方式更为简便。     

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。     

环境监测用空气中二氧化碳标准气体的研制

介绍了环境监测用空气中二氧化碳标准气体的制备方法。该标准气体的均匀性和稳定性通过气相色谱法进行了考察,并用比对误差确认了其称量法配制值的准确性。配制的标准气体的浓度为（10～1000）×10^-6（mol／mol）,定值不确定度小于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%。     

扩散管标准气体及其动态配气方法的研究

按照ISO6145标准，设计、研制了新型标准气体动态配气装置；实现了微机对动态配气装置的各主要参数数据的实时监控、存储和处理；定量表述了系统压力、温度等主要参数的变化对扩散管扩散率的影响及其带来的不确定度；用该动态配气装置研制了10^-6mol／mol含量范围的氮中苯系物挥发性有机物扩散管标准气体，实验表明不确定度为2％-3％；配制的标准气体与静态容量法配气装置配制的标准气体进行了比较，相对偏差在3％以内。     

甲烷中微量气体标准物质分析方法研究及量值的比对

建立了甲烷中微量气体标准物质的分析方法和实验条件;考察了该分析方法的不确定度;得出甲烷中微量气体标准物质浓度在(1 ～50)×10-6(mol/mol)范围内,方法不确定度小于1％的实验结果.实验过程对重量法制备的系列气体标准物质量值进行了分析方法的比对,一致性验证结果在1％内吻合.该项研究成果代表国家最高实验室参与了...     

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。     

Detonation studies with nitric oxide, nitrous oxide, nitrogen tetroxide, carbon monoxide, and ethylene

This paper presents the results of detonation studies conducted by the Bureau of Mines on nitric oxide, nitrous oxide, nitrogen tetroxide, carbon monoxide, and ethylene to evaluate the potential hazards of these materials to explosive shock initiation. Charge arrangements, construction details, and interpretation of results are given.Nitric oxide was observed to be the simplest known molecule capable of detonation-detonating in all three phases. Nitrous oxide, as a solid, nonboiling liquid, and nitrogen tetroxide and carbon monoxide, as nonboiling liquids, could not be initiated to detonation. Ethylene, as a gas at elevated pressure, gave evidence of a mild reaction but did not detonate; as a nonboiling liquid, it could not be initiated to detonation.     

Preparation of accurate, low-concentration gas cylinder standards by cryogenic trapping of a permeation tube gas stream

National and international measurements are underpinned by accurate, low concentration standards. These standards are typically produced gravimetrically, or volumetrically, by a series of dilutions of the pure material by the balance gas. This blend technique is time-consuming and may involve the handling of pure, hazardous material. These problems have been overcome by developing a novel blend technique whereby the process gas stream, from an appropriate permeation tube, was cryogenically trapped in an aluminum cylinder. The permeation rate of the component is monitored by real time mass determinations using a magnetic suspension balance system. With the combination of the real-time calculated permeation rate, plus the use of a dilution system, a one step production of a very low concentration of the minor component in nitrogen gas can be achieved. This method was used to prepare low μmol/mol standards of propane, a known stable compound. Analysis of a conventional gravimetrically prepared 10 μmol/mol propane standard and a cryogenically prepared standard via a permeation gas stream resulted in agreement between the two of <0.1% at 10 μmol/mol, confirming the accuracy of the permeation method. After confirmation of the validity of the permeation/cryogenic trapping system, the propane permeation tube was replaced with a methyl mercaptan tube (a toxic, reactive compound) in balance nitrogen. After cryogenically trapping the methyl mercaptan output stream from the permeation system into a cylinder, the output stream and the cylinder gas mixture were analyzed. The results showed agreement of <0.6% for methyl mercaptan at 5, 10, 15, and 20 μmol/mol to the expected blend concentration, thereby demonstrating the validity of the method.     

二氧化碳中全氟异丁腈气体标准物质的研制

介绍了气瓶装二氧化碳中全氟异丁腈(C4F7N)气体标准物质的研制过程.标准混合气是通过将全氟异丁腈和二氧化碳充装到铝合金气瓶中制备而成,采用称量法定值.对原料气体中杂质的进行了测量,综合采用经典稳定性评估和同步稳定性评估对该气体标准物质的长期稳定性进行了研究.结果显示该气体标准物质在6个月内的稳定性良好.该标准物质在(...     

基于傅里叶红外光谱仪的高温含水烟气中低浓度一氧化氮精确测量研究

随着国家超低排放政策的深入,对烟气中污染物浓度精确测量提出了更高的要求.基于傅里叶红外光谱仪建立了高温含水条件下一氧化氮(NO)气体精确测量系统,在191℃条件下测量了含5％ ～ 20％水蒸气与摩尔分数为5 ～ 40 μmol/mol NO混合前后的吸收光谱,通过修正混合物中H2O的吸光度来精确确定NO浓度,并评价了系...     

The influence of precursor powders and processing parameters on the properties of SnO2-based gas sensors

Semiconducting tin oxide precursor powders were synthesized via three different chemical processing routes. The influence of powder processing conditions on the physical properties, e.g., particle size, surface area and phase composition of both uncalcined and calcined materials, was investigated. These powders were used to fabricate gas sensors using thick-film screen-printing technology. The effect of precursor powders, sintering conditions, sensor temperature and Pd catalyst on the carbon monoxide, methane, propane and ethanol gas sensing characteristics of the sensors were investigated. Sensors were also fabricated using tin oxide powders obtained from a commercial source and their gas sensing properties were also investigated. The data indicates that the powder processing methodology, sensor fabrication conditions and Pd catalyst can profoundly influence the physical characteristics as well as the gas sensing properties of the sensors.