几种6000系汽车板铝合金的结晶相

通过扫描电镜/能谱、X射线衍射以及金相分析,针对几种6000系汽车板铝合金,研究了不同的合金成分对结晶相的影响.结果表明,合金铸造时形成的结晶相为Al1.9CuMg4.1Si3.3,Al8(FeMnCr)2Si,Al5(FeMnCr)Si,Al4(MnFeCr)3Si2,Al5(MnFeCr)12Si7以及Mg2Si.随Mg/Si,Mg/Cu质量比及Mn含量的增大,Mg2Si和Al(FeMnCr)Si/Al(MnFeCr)Si型结晶相数量增多.均匀化时,除发生Al5(FeMnCr)Si向Al8(FeMnCr)2Si相的转变外,其他结晶相的类型不变.在随后的固溶处理和时效过程中,结晶相不再发生变...     

Replacement of alkali silicate solution with silica fume in metakaolin-based geopolymers

A metakaolin(Mk)-based geopolymer cement from Tunisian Mk mixed with different amounts of silica fume(SiO_2/Al_2O_3 molar ratio varying between 3.61 and 4.09) and sodium hydroxide(10M) and without any alkali silicate solution, is developed in this work. After the samples were cured at room temperature under air for 28 d, they were analyzed by X-ray diffraction(XRD), Fourier transform infrared(FTIR) spectroscopy, environmental scanning electron microscopy, mercury intrusion porosimetry, ~(27)Al and ~(29)Si nuclear magnetic resonance(NMR) spectroscopy, and compression testing to establish the relationship between microstructure and compressive strength. The XRD, FTIR, and ~(27)Al and ~(29)Si NMR analyses showed that the use of silica fume instead of alkali silicate solutions was feasible for manufacturing geopolymer cement. The Mk-based geopolymer with a silica fume content of 6 wt%(compared with those with 2% and 10%), corresponding to an SiO_2/Al_2O_3 molar ratio of 3.84, resulted in the highest compressive strength, which was explained on the basis of its high compactness with the smallest porosity. Silica fume improved the compressive strength by filling interstitial voids of the microstructure because of its fine particle size. In addition, an increase in the SiO_2/Al_2O_3 molar ratio, which is controlled by the addition of silica fume, to 4.09 led to a geopolymer with low compressive strength, accompanied by microstructures with high porosity. This high porosity, which is responsible for weaknesses in the specimen, is related to the amount of unreacted silica fume.     

正一级醇在合成ZSM—5沸石中的作用

在直接法合成ZSM-5沸石的基础上,使用乳化技术,以正一级醇为添加剂合成出一系列ZSM-5沸石。发现醇对ZSM-5沸石的成核没有影响,但对晶化起明显促进作用。醇系列沸石的硅铝比随所用醇的碳链长度增加而线性下降,对正己烷的吸附量随碳链长度增加而线性上升。     

Microstructure and properties of mullite-based porous ceramics produced from coal fly ash with added Al_2O_3

Using coal fly ash slurry samples supplemented with different amounts of Al_2O_3,we fabricated mullite-based porous ceramics via a dipping-polymer-replica approach,which is a popular method suitable for industrial application.The microstructure,phase composition,and compressive strength of the sintered samples were investigated.Mullite was identified in all of the prepared materials by X-ray diffraction analysis.The microstructure and compressive strength were strongly influenced by the content of Al_2O_3.As the Al/Si mole ratio in the starting materials was increased from 0.84 to 2.40,the amount of amorphous phases in the sintered microstructure decreased and the compressive strength of the sintered samples increased.A further increase in the Al_2O_3 content resulted in a decrease in the compressive strength of the sintered samples.The mullite-based porous ceramic with an Al/Si molar ratio of 2.40 exhibited the highest compressive strength and the greatest shrinkage among the investigated samples prepared using coal fly ash as the main starting material.     

4A分子筛对聚磷酸铵/季戊四醇膨胀阻燃剂协同作用的TGA/XPS研究

利用TGA/XPS技术比较研究聚磷酸铵/季戊四醇(APP/PER)-4A与APP/PER体系的热行为.通过热失重及Si/Al原子比和结合能等数据绘图,对图中曲线进行了详细的分析.对比研究表明TGA的第3热失重峰明显降低,XPS的Cls相对谱峰强度随温度明显增加.4A分子筛在低温下对APP/PER膨胀阻燃体系发生催化酯化反应,在高温下Si/Al原子比升高,产生表面层动力学运动.酸的活性增加,有利于APP/PER膨胀阻燃体系.     

乙醇重整制氢对马来酸酐原位加氢制备四氢呋喃的研究

制备了两种聚乙烯吡咯烷酮(PVP)稳定的γ-Al_2O_3负载型稀土金属催化剂(PVP-La/Al_2O_3,PVP-Ce/Al_2O_3),并首次将乙醇催化重整制氢运用于马来酸酐(MA)液相加氢制备四氢呋喃(THF)的过程中。同时,对比研究了一种PVP稳定的钯催化剂(PVP-Pd/Al_2O_3)催化马来酸酐加氢的活性。结果表明,两种稀土金属催化剂显示出比PVP-Pd/Al_2O_3更优的催化性能。进而,系统考察了反应条件对PVPLa/Al_2O_3催化马来酸酐加氢反应的影响。在优化的条件下,MA实现了100%的转化,THF的选择性超过95.0%,最高达到98.2%的THF选择性。     

纳米Al2O3/PVAc复合材料的制备与表征

用硝酸铝和碳酸铵为原料,以聚乙二醇为分散剂,采用溶胶-凝胶法制备了纳米Al2O3溶胶.用液-液混合分散法将制得的纳米Al2O3溶胶分散于聚醋酸乙烯酯(PVAc)的丙酮溶液中,得到无色透明的纳米Al2O3/PVAc复合溶胶,将溶胶刮涂制膜,得无色透明的Al2O3/PVAc复合膜.用透射电子显微镜和拉曼光谱对复合材料进行了表征.激光粒度分析仪分析表明,Al2O3在PVAc粒径在30～35 nm范围内,平均密度31.2 nm、体积平均27.5 nm、数均25.3 nm .Zeta电位值为-42.5 mV.并对Al2O3/PVAc复合溶胶进行紫外吸收测试,结果显示,与纯PVAc溶液相比,最大吸收峰蓝移10.4 nm,且吸光度增加2.3倍.     

MOCVD法制备金属-陶瓷功能梯度材料的研究

利用金属有机化学气相沉积（MOCVD）方法，以Mo（CO）6，Si（OC2H5）4为物源，在Al2O3陶瓷基片上制备了金属一陶瓷功能梯度材料，并用XPS，XRD，SEM等技术对其成分分布，物相组成和表面形貌进行测试和表征，结果表明：材料的组成沿厚度方向呈连续梯度变化，符合功能梯度材料的变化规律。     

异丙苯裂解反应动力学及HZSM—5沸石表面酸性的表征

采用脉冲微反色谱法研究在ＨＺＳＭ－５沸石上异丙苯裂解反应动力学，求是反应速率常数、活化能、吸附平衡常数和吸附热，并以该反应探针，对没硅铝比的ＨＺＳＭ－５沸石的表面酸性进行了表生上异丙苯裂解结果表明：随Ｓｉ／Ａｌ比的减少，ＨＺＳＭ－５沸石表面酸性增加。