稻壳灰制备TiO2-SiO2复合载体脱硝催化材料

鉴于农业废弃物稻壳灰中非晶态硅含量高的特点,以稻壳灰为原料,采用共沉淀法制备了以TiO₂-SiO₂复合材料为载体,锰、铈为活性组分的脱硝催化材料。探究了SiO₂的添加对催化材料微观结构的影响,并对不同硅含量催化材料的脱硝机理进行了相关分析。实验结果表明,与纯TiO₂为载体的催化材料相比,TiO₂-SiO₂复合材料为载体的催化材料表面颗粒大小均匀,呈蓬松状态堆积,比表面积及孔容都有所增加,弱酸性位点的数量也大大增加,当SiO₂与TiO₂的物质的量比为4∶1时,催化材料的脱硝效率可达90%以上。     

水泥生产全过程硫循环机制的研究进展

SO₂是水泥行业产生的主要大气污染物之一。国内外对水泥行业SO₂排放量进行了严格限定。随着劣质原燃材料及替代燃料的大规模使用,更多的硫将被带入水泥生产过程中。这不仅会引起SO₂排放水平的增高,而且会加重硫在水泥窑炉内的循环富集,影响窑炉的正常操作,同时对熟料质量产生影响。 水泥生产过程中的硫由原料和燃料带入。其中,部分原料硫在预热器内转变为SO₂并随烟气离开,在生料磨和收尘器内被生料部分吸收,并再次进入预热器,形成了硫在预热器和生料磨、收尘器间的低温循环。未转变为SO₂的原料硫和燃料硫在水泥窑炉高温环境下形成SO₂,并被分解炉内的碱性氧化物吸收,形成硫酸盐进入回转窑,在回转窑烧成区部分硫酸盐发生分解,产生的SO₂再次进入分解炉,由此形成了硫在分解炉-回转窑间的高温循环。 围绕水泥生产过程硫的低温循环和高温循环,国内外开展了大量研究。围绕硫的低温循环,首先揭示了水泥生产排放的SO₂主要是由原料中硫铁矿和有机硫的氧化反应引起。硫铁矿的氧化温度约为400 ℃,反应产物以FeSX、Fe₂O₃为主。根据反应条件的差异,硫铁矿氧化机理包括直接氧化和先分解为硫黄铁矿再氧化。在预热器内CaCO₃和CaO可吸收部分SO₂,其中CaCO₃对SO₂的吸收为直接硫化反应,反应速率受烟气温度、水分含量、CO₂浓度等影响;部分研究者对CaO在预热器内吸收SO₂提出争议,认为CaO会优先与CO₂反应而影响其对SO₂的吸收。生料磨内SO₂的吸收效率被认为随烘干温度升高而降低,随原料水分含量增加而提高,固硫产物以CaSO₃·1/2H₂O为主,其会在生料颗粒表面富集。围绕硫的高温循环,研究结果表明硫酸盐在回转窑内的分解反应受温度、O₂浓度、硫碱比等影响。水泥窑协同处置替代燃料时产生的热解气体会显著降低CaSO₄的分解温度,促进SO₂释放;该现象随着替代燃料粒径的减小、挥发分含量的增加而加剧。熟料中硫的存在形式主要为K₂SO₄、3K₂SO₄·Na₂SO₄、K₂SO₄·2CaSO₄、CaSO₄或替换其他物质存在于硅酸盐矿物中,熟料中硫含量的增加会稳定C₂S而抑制C₃S形成。 本文综述了水泥生产全过程硫的循环机制,聚焦硫的低温和高温循环。围绕硫的低温循环,阐述了生料含硫形式及其检测方法、硫铁矿氧化及SO₂释放特性、CaCO₃和CaO在预热器环境下对SO₂的吸收机理以及粉磨过程生料的固硫作用;围绕硫的高温循环,阐述了硫在水泥窑炉内的挥发与循环机制、替代燃料对硫释放的影响、硫在熟料中的存在形式及对熟料质量的影响。     

绿色复合水泥的制备及性能研究

用10%～20%的水泥熟料及大量的以锰渣和钢渣为主的工业废渣配置绿色复合水泥.对砂浆试样进行了强度测试,同时利用孔结构测试及电子显微分析等现代测试方法对试样水化硬化过程和水化机理进行了研究,结果表明,试验配制低熟料、高废渣的绿色复合水泥是可行的,其对节约水泥熟料、充分利用工业废渣有很大好处.     

共沉淀法合成近零膨胀ZrW2O8/ZrO2复合陶瓷的致密化

采用化学共沉淀法合成前驱体,经1150℃ 烧结3.5 h得到近零膨胀26 wt% ZrW₂O₈/ZrO₂复合陶瓷,并利用X射线衍射仪、扫描电镜和热膨胀仪研究了原料中加入Al(NO₃)₃·9H₂O对26 wt% ZrW₂O₈/ZrO₂复合陶瓷的相组成、致密度和热膨胀性能的影响。研究结果表明,少量添加Al(NO₃)₃·9H₂O可有效提高复合材料致密度,所得复合陶瓷的组分仍为立方结构的α-ZrW₂O₈和单斜的m-ZrO₂,其中添加2.21 wt% Al(NO₃)₃·9H₂O的复合材料的致密度达到理论密度的98.67%,且对复合陶瓷的热膨胀性能影响不大。其促进致密化机制为晶界处低熔点液相物质Al₂(WO₄)₃提高了复合材料的烧结性能,消除气孔促进致密化。     

富氧型高活性吸收剂制备及同时脱硫脱硝特性研究

以粉煤灰、工业石灰、氧化性添加剂为原料,制备了具有良好同时脱硫脱硝性能的富氧型高活性吸收剂.研究了添加剂加入量、Ca/(S+N)比等重要因素对烟气脱硫脱硝效果的影响;通过SEM分析和BET数据分析,探讨了吸收剂的物理特性与活性关联性.该高活性吸收剂具有99%的脱硫和86%的脱硝特性.     

原位漫反射红外光谱研究NO和NH3在MnOx/TiO2催化材料上的吸附行为及反应机理

MnO_x/TiO₂催化材料在选择性催化还原过程中表现出了较好的低温催化活性,为了深入了解其作用机理,进一步改善催化活性,本工作采用原位漫反射红外光谱法系统地分析了NO和NH₃在MnO_x/TiO₂催化材料上的单吸附和共吸附行为。分析认为,该催化材料表面发生的选择性催化还原过程符合Eley-Ridal机理,催化反应发生在吸附态的NH₃和气态NO之间,而吸附态的NO及后续生成的硝酸盐、亚硝酸盐等物质会占据催化材料的活性位点,影响其对NH₃的吸附,进而导致脱硝活性下降。     

醋酸钙/飞灰复合脱硫脱硝剂热解性能实验研究

为了提高脱硫脱硝效率同时合理利用火电厂产生的飞灰,研究了醋酸钙中加入飞灰制备的复合脱硫脱硝剂的热解性能。对不同条件下制得的醋酸钙/飞灰复合脱硫脱硝剂的热重特性、X射线衍射图谱、比表面积、扫描电镜结果等进行了分析,结果表明:利用醋酸钙和飞灰水合制备的脱硫脱硝剂具有比单纯的醋酸钙和飞灰更大的比表面积;经过900℃煅烧后脱硫脱硝剂孔隙结构最好;脱硫脱硝剂经过900℃煅烧后的热解产物(SiO2、Al2O3、Fe2O3和CaO)有助于脱除烟气中的硫氧化物和氮氧化物。     

熔渗法制备SiC/ FexSiy 复合材料显微结构和性能

用Fe_xSi_y (Fe₃Si, Fe₅Si₃, FeSi ) 熔体自发浸渗SiC 粉体预制件制备出致密度高达9615 %的SiC/ Fe_xSi_y复合材料。利用XRD、OM 和SEM 等对复合材料的相组成、显微结构和力学性能进行了分析和表征。研究发现, 自发浸渗过程中SiC 在Fe_xSi_y 熔体中有溶解和析出, 导致复合材料的相组成和显微结构发生变化。Fe₃Si 渗入后, 复合材料中有碳析出, 并生成Fe₅Si₃ 和FeSi 两种新相;Fe₅Si₃ 和FeSi 的渗入无碳析出, 而是发生碳化硅烧结、粒子合并和晶粒长大;Fe₅Si₃ 熔体渗入超细碳化硅(0.5μm ) 粉体预制件后, 生成大的碳化硅晶粒和碳化硅单晶。借助CHEMSAGE 热力学数据库对1873 K 时Fe-Si-C 体系的平衡相图进行了定量分析, 研究了SiC 在Fe_xSi_y 熔体中的稳定性;解释了铁的三种硅化物浸渗后, SiC 颗粒形态的变化。通过对复合材料显微硬度、弯曲强度和可靠性(威布尔系数) 的测试, 分析了熔渗法SiC/ Fe_xSi_y 复合材料结构和性能的关系。     

原位聚合法制备聚苯胺改性MoS2及其环氧复合涂层的防腐性能

为提高环氧涂料的防腐性能,本文引入MoS₂纳米片作为阻隔剂,并在MoS₂纳米片表面原位聚合聚苯胺(PANI),制备了夹层结构i-PANI@MoS₂纳米片,利用PANI提高涂层的导电性,达到阳极钝化的效果。研究发现,当PANI与MoS₂的摩尔配比增大到7∶1时,MoS₂片层表面被PANI均匀覆盖,改性效果最好。与环氧树脂复合后,i-PANI@MoS₂-7纳米片在环氧树脂中均匀分散,复合涂层导电率提高,PANI与MoS₂起到了协同防腐作用,此时i-PANI@MoS₂纳米片既作为涂层中的阻隔剂,又作为电化学腐蚀保护剂,因此复合涂层具有最大的阻抗值、最大腐蚀电压以及最小的腐蚀电流密度,防腐性能优异。但PANI与MoS₂配比进一步增大,MoS₂纳米片表面的聚苯胺会发生团聚,导致复合涂层的防腐性能下降。     

Co/ATO复合薄膜的结构与电磁光特性

以低成本的无机盐 SnCl₂·2H₂O、SbCl₃和Co(NO₃)₂·9H₂O 为原料,采用溶胶-凝胶法与浸渍提拉技术成功地制备出Co掺杂的ATO(Sb掺杂SnO₂)复合薄膜。利用XRD、SEM、四探针电阻仪、紫外-可见光分光光度计及振动样品磁强计(VSM)等测试方法对Co/ATO复合薄膜的结构与物性进行了表征与评价。结果表明：少量的Co 掺杂ATO复合薄膜仍保持四方金红石结构,复合薄膜中的晶粒分布均匀,其晶粒尺寸分布为4～7 nm;随着Co含量的增加,Co/ATO复合薄膜的电阻率呈现出先降低后提高,且当Co含量为0.5 mol %时,Co/ ATO复合薄膜的电阻率最低为5. 6×10- 3Ω·cm;在400～700 nm可见光范围内,平均透过率达到90 %以上,其光学带隙在3.9～4.0eV之间,且随着Co含量的增加,可见光透过率和光学带隙呈下降趋势;Co含量为3.0 mol%的ATO复合薄膜具有室温铁磁性,其矫顽力约为100Oe,磁性根源主要归结为磁性原子与基体载流子相互作用的结果。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from     

CNAS Passes APLAC's PTP Review

正The review group of Asia Pacific Laboratory Accreditation Cooperation(APLAC)carried out a 4-day peer review of the proficiency testing provider(PTP)for China National Accreditation Service for Conformity Assessment(CNAS)from July 28 to 31,2014.CNAS passed the PTP review with excellent performance.Two senior peer reviewers of APLAC made a comprehensive,rigorous and detailed review of CNAS’s PTP accreditation activities,and made the on-spot inspection of the review groups in Shanghai and Shenzhen respectively.     

新闻(英文)

正China and Greece Sign the Standardization Cooperation Agreement Witnessed by Chinese Premier Li Keqiang and Greek Prime Minister Antonis Samaras,AQSIQ Minister Zhi Shuping and ELOT Chairman and Executive Director Angelos Tolkas signed the SAC-ELOT Standardization Cooperation Agreement.The Agreement is one of the critical cooperation documents signed during Li Keqiang’s visit in Greece,encouraging China and Greece to