制备方法对Al/Fe_2O_3纳米铝热剂性能的影响

分别采用超声共混法、机械球磨法和溶胶-凝胶法制备出Al/Fe2O3纳米铝热剂。研究了3种制备方法对纳米铝热剂晶型、平均粒径、形貌、比表面积和热反应性能的影响。结果表明,超声共混法只能使两组分简单地混合在一起;机械球磨法通过机械作用力使两组分混合均匀,但部分Al颗粒破裂,平均粒径减小;溶胶-凝胶法制备的Fe2O3凝胶均匀包裹着Al颗粒,形成核壳结构的Al/Fe2O3纳米铝热剂,有效地保护了Al颗粒,同时纳米铝热剂具有高的比表面积,固—固反应放热量为896J/g。     

Fe2O3/Ni2O3/Al2O3催化剂制备及其催化氧化靛蓝废水研究

以三氧化二铝为载体,采用浸渍沉淀法制备系列Fe2O3/Ni2O3/Al2O3催化剂。采用TG-DTA,XRD及ESEM等技术对催化剂进行表征,确定催化剂的最佳焙烧温度为460℃。以次氯酸钠为氧化剂,同时考察m(三氧化二镍)/m(三氧化二铝)、m(三氧化二铁)/m(三氧化二镍)、m(次氯酸钠)∶m(靛蓝废水)、pH对印染靛蓝废水处理的影响。结果表明:m(三氧化二镍)/m(三氧化二铝)=0.3,m(三氧化二铁)/m(三氧化二镍)=0.04,m(次氯酸钠)∶m(靛蓝废水)=1∶11,pH=7,反应温度为20℃,常压反应时间为2 h时,COD的去除率为95.3%。     

Fe-Al/Al2O3复合材料与ZTA陶瓷的抗热震性研究

对Fe-Al／Al2O3复合材料的抗热震性进行了测定。通过与ZTA陶瓷的抗热震性对比，分析了该复合材料具有较好抗热震性的原因。试验发现：Fe-Al／Al2O3复合材料的残余硬度和抗压强度随AT的变化有明显差异。在热震温差很高时，Fe—Al相的高温热强性改善了Fe-Al／Al2O3复合材料的抗热震性。     

镍/氧化铝加氢催化剂的制备及性能研究

羟基新戊醛（HPA）的加氢多采用贵金属和铜系催化剂,为了更好地降低催化剂生产成本和操作成本,分别对比了共沉淀法和浸渍法制备的镍/氧化铝催化剂,并以HPA为原料,在固定床装置上考察了系列催化剂加氢合成新戊二醇（NPG）的催化性能。采用X射线衍射（XRD）、氮气物理吸附（BET）、一氧化碳脉冲吸附等方法进行表征,结果表明,浸渍法制备的20%镍/氧化铝催化剂,比表面积较大,金属分散性好,且催化剂中的镍物种易被还原,其反应性能良好。在相对较温和的反应条件下,即反应温度为103 ℃、反应压力为3 MPa、液时空速为1 h^-1、氢醛物质的量比为10时,HPA转化率为100%,NPG选择性为99.3%。在1 000 h的长周期评价过程中,该催化剂保持了较好的活性,具有更好的工业化前景。     

Investigation of novel multiscale textures for the enhancement of the cutting performance of Al2O3/TiC ceramic cutting tools

Currently, the high temperature and severe friction conditions at the tool-chip interface are the main reasons for ceramic tool wear failures. Surface texturing as a geometric extension for cutting tools is a promising way to extend their service life. In this study, a novel type of multiscale texture was developed, and its effect on the cutting performance of an Al₂O₃/TiC ceramic cutting tool while machining AISI H13 steel was explored in a conventional cooling environment. The cutting force, cutting temperature, and tool wear morphology were investigated at cutting velocities ranging from 80 to 249 m/min. Microgroove textured Al₂O₃/TiC ceramic tools were prepared for comparison. The results show that the structure of the multiscale textures maintained good integrity over the range of cutting velocities. Thus, the synergistic effect of the microscale and nanoscale textures promoted the introduction and permeation of the cutting fluid. Therefore, the multiscale textures effectively enhanced the cutting performance of the Al₂O₃/TiC ceramic tools.     

Promoting effect of NiAl2O4 for supported Ni particles on sprayed Ni/Al2O3 catalysts

Ni/Al₂O₃ catalysts were prepared by the spray reaction method. The NiO particles supported on NiAl₂O₄ were stabilized against the aggregation and converted into smaller Ni particles by H₂ reduction. The Ni particles stabilized on NiAl₂O₄ marked anomalous high activity for CO hydrogenation, due to the stronger interaction between Ni and NiAl₂O₄. This revised version was published online in July 2006 with corrections to the Cover Date.     

The cutting performance of Al2O3 and Si3N4 ceramic cutting tools in the milling plywood

ABSTRACT

This research focuses on the cutting performance of Al₂O₃ and Si₃N₄ ceramic cutting tools in up-milling plywood, the results of which are as follows. First, whether the tool material is Al₂O₃ or Si₃N₄ ceramic, the cutting forces at low-speed cutting were less than those at high-speed cutting, and the machining quality at low-speed cutting was greater than that at high-speed cutting. Then, whether at low- or high-speed cutting, the cutting forces of Al₂O₃ cutting tools were higher than those of Si₃N₄ cutting tools, and the machining quality of plywood milled by Al₂O₃ ceramic cutting tools was poorer than that milled by Si₃N₄ ceramic cutting tools. Finally, Si₃N₄ ceramic cutting tools were more suitable to machine the wooden productions with much glue content than Al₂O₃ ceramic cutting tools for the better machined quality.     

Effect of heat release conditions on the phase composition of the combustion products of a Fe<Subscript>2</Subscript>O<Subscript>3</Subscript>/TiO<Subscript>2</Subscript>/Al/C thermite mixture

An X-ray method was used to study the phase composition of the combustion products of a Fe₂O₃/TiO₂/Al/C thermite composite mixture, in particular, during combustion of samples under cooling by water. The data of the experiments are compared with the results of thermodynamic calculations. A probable explanation of the reasons of the angular displacement of the line of iron in the X-ray spectrum of the combustion products and a mechanism for the crystallization of an eutectic TiC + α-Fe mixture from the melt of the Ti/Fe/C ternary system. The composition of the combustion products was found to be different from the equilibrium one, which is manifested in the presence of defects in the carbon sublattice of titanium carbide. A probable explanation of the deficiency of carbon is proposed. __________ Translated from Fizika Goreniya i Vzryva, Vol. 44, No. 4, pp. 39–43, July–August, 2008.     

甲烷催化燃烧用LaMn/Al_2O_3催化剂研究

为获得具有优良低温活性的甲烷燃烧用催化剂,采用稀土La作为助剂制备了系列Mn基催化剂,借助X射线衍射(XRD)、X射线光电子能谱(XPS)和程序升温还原(TPR)技术对催化剂的结构进行了表征,并评价了其对甲烷燃烧的低温催化性能。结果表明,La助剂的添加显著促进了活性组分MnO2的分散,使其更易于还原,且使Mn4+和晶格氧富集于催化剂表面,因而显著提高了催化剂对甲烷催化燃烧的低温活性。当La质量分数为5%时,催化活性最高,甲烷50%转化率对应的温度较未加助剂时降低了70℃,且完全转化的温度低至480℃。     

FeTiO3-Al-C系统的反应热力学及Al2O3-TiC/Fe 复合材料的制备

充分利用天然矿物钛铁矿（FeTiO3）中的铁和钛,采用反应烧结技术,成功制备了Al2O3-TiC/Fe陶瓷复合材料.在真空热压炉中实现了合成与烧结一体化,为陶瓷复合材料的低成本制备进行了有益的探索研究.对钛铁矿-Al-C系统的热力学过程进行了详细的理论分析.研究表明：系统主要发生铝热还原反应,中间产物为多种钛的氧化物,系统反应后热力学上最为稳定的物质为Al2O3,TiC和Fe;系统反应最高温度低于Al2O3的熔化温度.通过实验研究,分析了产物的物相、结构和性能.反应烧结的最终产物主要为TiC,Al2O3和Fe.此外,还有少量Fe-Al相,大部分为Al2O3.TiC晶体颗粒尺寸约为3～5 μm,分布较为均匀,Fe分布于Al2O3,TiC晶粒之间.Y2O3和Cr2O3添加剂可以提高复合材料的抗弯强度.     

Cu-Zn-Ni/Al2O3复合脱硫剂深度脱硫性能及Ni含量对其影响的实验研究

用共沉淀法加浸渍法制成Ni含量分别为0、5%、10%的Cu-Zn-Ni/Al2O3复合三元脱硫剂,通过LPG脱硫实验,研究了它们的脱硫性能.实验结果表明,Cu-Zn-Ni/Al2O3脱硫剂具有深度脱硫性能(<10×10-9),并且随着温度的升高,脱硫性能逐渐增强,最终会趋于稳定.空速(SV)为400、1200 h-1时...     

氧化铝载体对镍/氧化铝催化剂性能的影响

氧化铝是化工催化行业广泛应用的催化剂载体。油脂加氢催化剂主要是以氧化铝为载体、镍为主要活性组分的催化剂。在制备镍/氧化铝催化剂的过程中,载体氧化铝使用的最佳条件：载体在共沉淀反应前加入,载体氧化铝比表面积为340.6 m2/g,载体氧化铝加入量为m（镍）∶m（氧化铝）=5∶4,反应的老化时间为45 min。在此条件下,制备的镍/氧化铝催化剂活性最高,应用效果最好。     

共沉淀法制备Ni/Al2O3催化剂的研究

油脂加氢催化剂是以金属镍为活性组分、氧化铝为载体制备的Ni/Al2O3催化剂。在制备催化剂过程中,其合成条件直接影响着催化剂的最终活性。以工业硝酸镍、碳酸钠和自制氧化铝粉为原料,利用共沉淀的方法制备加氢催化剂,考察了反应温度、反应时间、反应液pH及反应过程中搅拌转速对催化剂活性的影响。通过实验数据汇总分析,最终确定制备Ni/Al2O3油脂加氢催化剂的最佳条件：反应温度为85 ℃、反应结束时溶液pH=8.0、反应时间为1.5 h、搅拌转速为600 r/min。在此条件下制备的Ni/Al2O3催化剂,经棕榈油加氢评价后测定的碘值最低。     

Y2O3添加量对Al2O3/ZrO2复合材料烧结行为和热机械性能的影响

研究了Y2O3添加量对Al2O3/ZrO2复合材料烧结行为和热机械性能(高温抗折强度和抗热震性)的影响,并研究了这些性能与物相组成和显微结构间的关系.结果表明:Y2O3在Al2O3/ZrO2复合材料中起稳定ZrO2晶型、改善烧结致密化、提高高温抗折强度和抗热震性的作用.当Y2O3添加量为1%时,试样的烧结性能和高温抗折强度较佳,体积密度、显气孔率和线收缩率分别为3.27 g/cm3、21.95%和7.43%,高温抗折强度达29 MPa;抗热震性则在Y2O3添加量为0.5%时较佳,其残余强度保持率为71%.Y2O3对Al2O3/ZrO2复合材料烧结性能和热机械性能的影响与Y2O3/ZrO2固溶体的形成、Al2O3和ZrO2晶体间的结合程度及试样中微裂纹含量密切相关.     

PTFE/Al/Fe_2O_3复合材料的性能

研究了以聚四氟乙烯(PTFE)为基体,Al/Fe_2O_3混合物为填料的复合材料的准静态压缩性能和撞击感度,探讨了不同烧结温度和不同PTFE含量对复合材料性能的影响。结果表明,随着PTFE含量以及烧结温度的增加,材料强度均呈现先增加后降低的趋势。PTFE质量分数在70%和80%的PTFE/Al/Fe_2O_3复合材料在烧结温度340~370℃的范围时,能够在准静态压缩过程中产生剧烈反应,发出爆炸声和明亮的火光。370℃烧结的PTFE质量分数为70%的复合材料的撞击感度最高,特性落高值仅有37 cm,非常敏感。在同一烧结温度下,随着PTFE含量的增加,复合材料的撞击感度先增加后降低;PTFE含量相同时,随烧结温度的增加,材料撞击感度为先增加后降低。     

超级铝热剂Al/Fe_2O_3对硝化棉热分解特性的影响

采用水热法制备了纳米Fe_2O_3,并用超声分散法将其与纳米Al颗粒复合制备了超级铝热剂Al/Fe_2O_3,利用X-射线粉末衍射(XRD)、透射电子显微镜(TEM)、扫描电镜及能量散射光谱仪(SEM-EDS)对复合物的物相、组成、形貌和结构进行了分析表征,采用差示扫描量热法(DSC)和热红联用技术(TG-FTIR)研究了Al/Fe_2O_3对硝化棉(NC)热分解过程的影响。结果表明,Al/Fe_2O_3-NC和NC的热分解过程遵循Avrami-Erofeev方程f(α)=1.5(1-α)[-ln(1-α)]1/3;超级铝热剂Al/Fe_2O_3可降低硝化棉的表观活化能、临界点火温度和临界爆炸温度,在促进硝化棉O-NO_2键断裂和凝聚相二次自催化反应中起到至关重要的作用。     

Effect of nitrogen pressure and aluminum content in a Fe2O3/Al mixture on combustion and chemical composition of combustion products

The possibility of obtaining cast aluminum oxynitrides in the combustion of iron-aluminum termite in a nitrogen atmosphere is shown. The combustion was carried out in a sealed reactor at an initial nitrogen pressure up to 10 MPa. The effect of the initial nitrogen pressure and aluminum content (in excess of stoichiometric) in the initial mixture on the bound nitrogen content in the oxide product of the synthesis is studied. Based on thermodynamic calculations and experimental results, a model was proposed for the chemical transformation of the initial mixture in the combustion wave with formation of a two-phase high melt.     

Regeneration of S-poisoned Pd/Al2O3 and Pd/CeO2/Al2O3 catalysts for the combustion of methane

This work investigates the regeneration of S-poisoned Pd/Al₂O₃ and Pd/CeO₂/Al₂O₃ catalysts under different CH₄ containing atmospheres. Under lean combustion conditions in the presence of excess O₂, partial regeneration took place for both systems only above 750 °C after decomposition of stable sulphate species adsorbed on the support. Under alternate lean combustion/CH₄-reducing pulse regeneration is markedly anticipated down to 550–600 °C. Experiments evidenced an effective role of ceria in preventing PdO from sulphation and in promoting regeneration via sulphates decomposition under reducing conditions.     

Fe2O3/泡沫镍复合材料电磁屏蔽效能研究

本文以电沉积法制备了泡沫镍材料,并在泡沫镍材料空隙内生长了纳米棒状Fe2O3,制备了Fe2O3/泡沫镍复合材料,测试了复合材料在Ku(12.4～18 GHz)频段的介电常数和电磁屏蔽效能.实验结果表明:复合材料具有较高的介电常数,介电常数的实部和虚部最大值可分别达到51和100.该复合材料的电磁屏蔽效能则随频率的增大而增加,并在20～33 dB范围内变化,表明该材料具有潜在的实际应用价值.     

Al2O3/Fe2O3吸附剂脱除硫化氢的性能

采用共沉淀法制备了氧化铝改性的氧化铁吸附剂,并采用比表面积(BET)、X射线衍射(XRD)技术对吸附剂进行了表征。在固定吸附床上,考察了制备条件及吸附条件对吸附剂脱除硫化氢性能的影响。结果表明,引入氧化铝能显著提高氧化铁对硫化氢的吸附净化能力。氧化铁与氧化铝质量比为1∶0.5,造孔剂十六烷基三甲基溴化铵(CTAB)质量分数为2%,焙烧温度500℃时,采用共沉淀法的负载氧化铝吸附剂的吸附效果最好。在气速20 mL/min,吸附温度80℃时,脱硫率和穿透硫容可分别达到99.3%和105 mg/g,其穿透硫容比未经改性的活性氧化铁提高了49.8 mg/g。