Eu3+浓度对Ca3Al2O6:Eu3+晶体结构和发光性能的影响

以β-丙氨酸和尿素为燃料,采用溶液燃烧法在低温450℃下合成制备了Ca3Al2O6:Eu3+荧光粉。样品的发射光谱由位于594 nm、617 nm、653 nm及700 nm处的4组线状峰构成,分别对应Eu3+的5D0→7Fj(j=1~4)特征跃迁,其中617 nm处的峰最强,样品呈现红色发光。考察了Eu3+掺杂浓度对晶体结构和发光性能的影响。结果呈示:随着掺杂浓度的增加晶格常数逐渐减小,[O—Al—O]的对称伸缩振动Raman峰蓝移;在低掺杂浓度时荧光强度逐渐增大,掺杂6%时达到最大,之后出现浓度猝灭现象,猝灭机制为交互作用;Eu3+的5D0→7F2与5D0→7F1跃迁强度比随着掺杂浓度的增加逐渐增大,掺杂的Eu3+主要取代处于非对称中心的Ca2+。     

Preparation of TiAl/Al_2O_3 composites by combustion synthesis

0　ＩＮＴＲＯＤＵＣＴＩＯＮＴｉｔａｎｉｕｍａｌｕｍｉｎｉｄｅｓｂａｓｅｄｏｎＴｉＡｌｈａｖｅｅｘｃｅｌ ｌｅｎｔｐｏｔｅｎｔｉａｌｔｏｔａｋｅｔｈｅｐｌａｃｅｏｆｃｏｎｖｅｎｔｉｏｎａｌｔｉｔａｎｉ ｕｍａｎｄｎｉｃｋｅｌａｌｌｏｙｓｉｎａｄｖａｎｃｅｄｓｐａｃｅｃｒａｆｔｄｕｅｔｏｔｈｅｉｒｌｏｗｄｅｎｓｉｔｙ ,ｇｏｏｄｅｌｅｖａｔｅｄ ｔｅｍｐｅｒａｔｕｒｅｓｔｒｅｎｇｔｈａｎｄｈｉｇｈｒｅｓｉｓｔａｎｃｅｔｏｏｘｉｄａｔｉｏｎ[1～ 3] .Ｈｏｗｅｖｅｒ ,ｔｈｅｗａｙｔｏｐｒａｃｔｉｃａｌａｐｐ…     

Coating of LiNi1/3Mn1/3Co1/3O2 cathode materials with alumina by solid state reaction at room temperature

Alumina coated LiNi1/3Mn1/3Co1/3O2 particles were obtained by a simple method of solid state reaction at room temperature. The reaction mechanism of solid state reaction at room temperature was investigated. The structure and morphology of the coating materials were investigated by XRD, SEM and TEM. The electrochemical performances of uncoated and Al2O3-coated LiNi1/3Co1/3Mn1/3O2 cathode materials were studied within a voltage window of 3.00-4.35 V at current density of 30 mA/g. SEM, TEM and EDS analytical results indicate that the surface of LiNi1/3Mn1/3Co1/3O2 particles is coated with very fine Al2O3 composite, which leads to the improved cycle ability though a slight decrease in the first discharge capacity is observed. It is proposed that surface treatment by solid state reaction at room temperature is a simple and effective method to improve the cycle performance of LiNi1/3Co1/3Mn1/3O2 particles.     

反应条件对CuO／Y2O3-ZrO2-Al2O3催化甲烷燃烧性能的影响

采用溶胶凝胶法制备CuO／Y2O3-ZrO2-Al2O3催化剂。研究了反应气甲烷与空气体积比和反应气体流速对CuO／Y2O3-ZrO2-Al2O3,催化剂性能的影响,结果显示：VCH4：VAir=1：25且气体流速为1800Loh-1时,该催化剂具有较好的催化活性和高温热稳定性。     

Au/Al2O3催化剂上环己烷氧化

针对金催化剂制备过程的复杂性和氯离子残留问题,介绍一种负载型金催化剂Au/Al2O3的制备方法和考察该催化剂在环己烷氧化中的催化性能.采用浸渍-氨洗法制备Au/Al2O3催化剂,并应用电感耦合等离子体原子发射光谱(ICP-AES)、X射线衍射(XRD)和透射电子显微镜(TEM)对其进行表征.以氧气氧化环己烷制备环己酮和环己醇为研究对象,考察金质量分数、反应温度、压力、时间等因素对催化活性的影响.结果表明,随着金质量分数增加,金颗粒增大,催化剂的活性降低,在150℃、1.5MPa条件下反应3h,Au实际质量分数为0.58%的Au/Al2O3催化剂上环己烷转化率为8.96%,环己酮、环己醇和环己基过氧化氢三者的总选择性为93.52%.此外,循环实验表明Au/Al2O3催化剂具有一定的稳定性.     

Pr~(3+)掺杂的YAG:Ce~(3+)荧光粉的发光性能

以A1(NO3)3.9H2O、Y(NO3)3.6H2O和Ce(NO3)3.6H2O为氧化剂,尿素为还原剂,采用低温燃烧法合成了Pr3+掺杂的YAG:Ce3+光致发光超细荧光粉,研究了镨离子和尿素的掺杂量对YAG:Ce3+粉体发光性能的影响。结果表明,在450℃的低温条件下,利用低温燃烧法可以制备较纯的Pr3+掺杂的YAG:Ce3+荧光粉;掺杂Pr3+增加红光区的发射峰有利于提高YAG:Ce3+荧光粉的显色性;当Pr3+的掺杂量为0.005 0、尿素的添加量按化合价计算的剂量比为1.2倍时用低温燃烧法所制备的YAG:Ce3+超细荧光粉的发光强度最高。     

Al2O3对3Ti/Si/2C体系自蔓延高温合成Ti3SiC2的影响

以3Ti/Si/2C粉体为原料,通过自蔓延高温合成技术合成了Ti3SiC2材料。研究了Al2O3助剂对自蔓延高温合成Ti3SiC2的影响。研究结果表明,3Ti/Si/2C粉体会发生自蔓延反应,产物的组成相为TiC、Ti3SiC2和Ti5Si3,产物中Ti3SiC2含量约为23%。添加适量的细粒度Al2O3可显著促进反应合成Ti3SiC2,3Ti/Si/2C/0.1Al2O3原料反应后得到的产物中Ti3SiC2含量达64%。     

Mechanism and kinetics analysis of AlN combustion synthesis

0　INTRODUCTIONAluminumnitride (AlN)isamaterialwhichpossess esoutstandingelectricalandthermalpropertiessuchashighthermalconductivity ,lowthermalexpansion ,gooddielectricstrength ,goodresistancetocorrosionandero sion ,andhighhardness .Presently ,AlNceramicisfind ingincreasedusageinsubstratesandpackaging ,cru cibles ,firingtilesandthermalfillersinpolymers ,adhe sivesandpottingcompounds[1] .Thetypicalcombustionsynthesis ,orself propagatinghigh temperaturesynthesis ,istheoldestandmostwell kn…     

Formation of CaO-TiO2-MgO-Al2O3 dual phase inclusion in Ti stabilized stainless steel

The formation of CaO-TiO2-MgO-Al2O3 dual phase inclusion in 321 stainless steel was investigated in the laboratory. The result indicated that the condition for the formation of CaO-TiO2-MgO-Al2O3 in 321 steel is [Ca]〉0.001wt%, [Ti]〉0.1wt%, and [A1]〉0.01wt%. The mechanism is the following： Al2O3 inclusion turns into CaO-Al2O3 after Ca-Si wire is fed into the molten steel; [Mg] is then obtained by reducing MgO in slag or crucible wall by [Al] and [Ti]; finally CaO-Al2O3 inclusion is changed into CaO-TiO2-MgO-Al2O3 by the reaction with [Mg], [Ti], and [O] in the molten steel simultaneously.     

氧化镁对铜铈催化剂CO氧化活性及抗硫性能影响

研究了氧化镁改性载体对铜铈复合氧化物催化剂的CO氧化活性、抗硫性能及烧焦助燃活性的影响。结果表明,以氧化铝为载体的铜铈复合氧化物催化剂具有较高的CO氧化活性,但抗硫中毒的性能稍差;用氧化镁对载体进行改性处理,不仅可以提高催化剂的CO氧化活性,当氧化镁改性剂用量达到20％(质量分数)以上,载体中出现了MgO结构碎片的晶相峰之后,还可明显提高其抗硫中毒的能力,以及硫中毒后氢气还原气氛中的还原再生能力。使催化剂进行烧焦助燃时表现出良好的烧焦助燃活性。     

制备方法对负载型FeS/Al_2O_3催化剂催化性能的影响

用原位合成法、水热法、共沉淀法和浸渍沉淀法分别制备了负载型纳米Fe2O3/Al2O3催化剂前驱体,并进一步将其还原和硫化制成FeS/Al2O3催化剂用于H2S分解制氢的反应中,同时用BET、XRD、TPR和IR等对催化剂或前驱体的比表面积、晶相结构、孔径分布、还原性和吸附性等进行了表征。结果表明,原位合成法制备的FeS/Al2O3催化剂平均粒径较小,比表面积较大,有利于催化剂的还原和硫化,H2S在该催化剂表面形成的化学吸附态较强,H2S容易发生解离,初活性高于其他方法制备的催化剂,反应60 h后催化剂的活性没有出现明显下降。     

Flame retardancy and its mechanism of polymers flame retarded by DBDPE/Sb2O3

The flammability characterization and thermal composition of polymers flame retarded by decabromodiphenylethane （DBDPE） and antimony trioxide （Sb2O3） were studied by cone calorimeter and thermogravimetry （TG）. The results show that ABS/DBDPE/Sb2O3 has the similar flammability parameters and thermal composition curves to ABS/DBDPO/Sb2O3. It suggests that DBDPE/Sb2O3 has the similar flame retardant behavior to DBDPO/Sb2O3. The heat release rate （HRR） and the effect heat combustion （EHC） curves of polymers flame retarded by DBDPE/Sb2O3 all decrease, but the mass loss rate （MLR） curve slightly increase. It shows that the decrease of HRR is not due to the increase of char formation ratio but the generation of incombustible gases. The major flame retardant mechanism of DBDPE/Sb2O3 is gas phase flame retardant mechanism. Increasing content of Sb2O3 in DBDPE/Sb2O3 can improve the flame retardant property and thermal stability of acrylonitrile butadiene styrene. Sb2O3 has a good synergistic effect with DBDPE.     

低温燃烧法制备YAG透明陶瓷纳米粉体

透明YAG陶瓷具有较好的化学稳定性、光学性能和高温性能,是单晶激光材料的有力替代品,纳米YAG粉体的合成有利于制备性能优异的YAG透明陶瓷．采用低温燃烧法,以Y2O3、Al（NO3）3·9H2O、柠檬酸、乙二醇为原料,采用TG／DSC,XRD和SEM等测试手段对YAG前驱体进行表征,对YAG前驱体在不同温度下进行煅烧．结果发现,在900℃左右已完全转变成YAG相,最终获得单分散、无团聚、形状规则的YAG纳米粉体．     

Pressureless reactive sintering mechanism of nanocrystalline Bi2O3-Y2O3 solid electrolyte

The nanocrystalline Bi2O3-Y2O3 solid electrolyte material was synthesized by pressureless reactive sintering process with Bi2O3 and Y2O3 nano mixed powder as raw materials, which was prepared by a chemical coprecipitation process. The study on the behavior of nano δ-Bi2O3 formation and its grain growth showed that the solid solution reaction of Y2O3 and β-Bi2O3 to form δ-Bi2O3occurs mainly in the initial stage of sintering process, and nano δ-Bi2O3 crystal grains grow approximately following the rule of paracurve ((D-D0)2=K.t) during sintering process. After sintered at 600℃ for 2 h, the samples could reach above 96% in relative density and have dense microstructure with few remaining pores, the δ-Bi2O3 grains are less than 100 nm in size.     

Al_2O_3-TiC复合材料放电等离子烧结(SPS)致密化研究

用燃烧合成及放电等离子烧结法制备出致密Al_2O_3-TiC复合材料;分析了烧结温度与材料致密度、显微结构及力学性能的关系;真空气氛、1650℃、保温5min烧结试样的相对密度达99.8％,断裂韧性为4.61 MPa·m~(1/2);更高温度下烧结,气相反应加剧,不利于致密度进一步提高,力学性能也有所下降。沿晶断裂是其主要断裂方式。     

Toughening mechanism of lined Al2O3-ZrO2 multiphase ceramics in SHS composite pipes

1. IntroductionEngineering ceramics is known worldwide becauseof its high operating temperature, corrosion resistanceand wear resistance. The ceramics-lined compositepipes are widely researched for their extensiveprospects in engineering application. The …     

不同方法制备La2O2CO3/ZnO催化乙醇转化的研究:孔结构和表面碱性的影响

利用共沉淀法和乙二醇燃烧法制备La₂O₂CO₃/ZnO两种催化剂，评价其对生物乙醇脱氢生成乙醛的催化活性，并采用FE?SEM, HR?TEM, FT?IR, XRD, BET，CO₂?TPD等研究手段对催化剂的形貌及表面碱性等物相结构进行表征. 结果表明，制备方法对催化剂形貌以及性能影响十分明显，乙二醇燃烧法形成的大孔结构有助于乙醇的转化，同时产物乙醛的选择性与催化剂表面碱性有关.     

铝热法合成NiAl／Al2O3复合材料

以铝粉和NiO粉为原料,采用铝热法合成了NiAl／Al2O3复合材料。通过X射线衍射分析仪（XRD）,扫描电子显微镜（SEM）并结合差示扫描量热仪（DSC）对其相组成、微结构和反应过程进行了分析。实验结果表明：850℃Al／NiO体系铝热反应被点燃,并自蔓延发生于整个反应系统;950℃保温40min,Al／Ni0体系铝热反应生成相互交织网状结构的NiAl／Al2O3复合材料。     

Ni／Al2O3催化剂催化乙醇水蒸气重整制氢的研究

为提高用于燃料电池的乙醇水蒸气重整制氢反应催化剂的活性,采用壳聚糖扩孔以Al2O3为载体,Ni为活性中心的催化剂。利用X射线衍射（XRD）、BET比表面测试手段对催化剂的结构进行了表征。考察了反应温度、水醇物质的量的比、液体进料空速等对反应的影响。结果表明,经600℃焙烧2h的催化剂,在水醇物质的量的比为3：1,液体进料空速（WHSV）为4．8h^-1,反应温度500℃时,产气量接近40mL／min,H2选择性达到68％。乙醇水蒸气重整制氢Ni／Al2O3催化剂的最佳反应温度为500～550℃,水醇物质的量的比一般控制在3：1～5：1范围内较好。     

Al/Y_2W_3O_(12)复合材料的制备、热膨胀及电性能研究

采用固相法制备Al/Y_2W_3O_(12)复合材料,研究了Al与Y_2W_3O_(12)以不同质量比合成样品的特性。X射线衍射表明:样品只含有Al和Y_2W_3O_(12),不存在Al对Y的取代。SEM和EDS分析表明:小颗粒Y_2W_3O_(12)嵌入在块状Al基底中,为嵌入式复合结构。热膨胀性能和电导率测试分析表明:当Al与Y_2W_3O_(12)的质量比7∶3时,Al/Y_2W_3O_(12)样品的线膨胀系数14.76×10-6/K(RT~600℃)约为Al的一半,呈现良好的导电性,其导电率为18.2 S/m可达Al的电导率的1/2,且Al/Y_2W_3O_(12)样品几乎不表现出吸水性。研究认为,该复合材料具有低膨胀和较高导电性是由于其特有的嵌入式结构所致。