The effects of Ni-addition on the crystal structure,thermal properties and morphology of Mg-based hydroxyapatites synthesized by a wet chemical method

Four Mg-based hydroxyapatites (HAps) doped with Ni at various amounts of 0, 0.6, 1.2 and 1.8?at% were prepared at the temperature of 870?°C by a wet chemical synthesis. The crystallite size, lattice parameters and crystallinity percent dramatically decreased with adding of Ni. The amount of HAp phase for all the Ni-containing samples is smaller than that of the Ni-free MgHAp. Furthermore, the lattice strain, stress and anisotropic energy density values were affected by the amount of Ni. The differential thermal analysis (DTA) measurements taken in the temperature range from 25 to 1000?°C showed that all the samples are thermally stable. No significant change in the morphology was observed. It was observed that the gradual introduction of Ni caused the Ca-deficiency.     

镍盐应用及其浸渍方法研究进展

镍基催化剂由于高催化活性和低成本的特点,常作为贵金属催化剂替代品,工业应用前景广阔。以往研究主要集中于镍催化剂的改性方法和制备工艺。介绍近年来国内外无机镍盐及有机镍盐的基础应用及工艺特点,综述镍盐作为前驱体在催化剂上的应用及不同浸渍法制备的催化剂,指出不同前驱镍盐和浸渍方法对催化剂性能的影响。     

浸渍顺序对Mo-Ni加氢催化剂结构和性质的影响

以γ-Al2O3为载体,制备Mo、Ni单组分及双组分催化剂,考察浸渍顺序对催化剂结构的影响.通过氮物理吸附、TPR、和XPS等技术进行表征,结果表明,共浸渍法制备催化剂,有利于活性金属组分的还原,并能提高活性金属组分的分散度,同时使催化剂表面具有较高的Ni/Mo原子比.     

核壳聚合物负载茂金属催化剂及乙烯聚合

采用半连续种子乳液聚合法,得到了粒径为280 nm左右的以聚甲基丙烯酸甲酯 (PMMA)为核、聚苯乙烯(PS)为壳的PMMA/ PS核壳结构聚合物和以PS为核、PMMA为壳的PS/PMMA核壳结构聚合物.并分别以上述二种核壳聚合物为载体,超临界CO2为溶剂,采用超临界流体浸渍法负载二氯二茂钛(Cp2TiCl2)催化剂,得到PMMA/PS-Cp2TiCl2和PS/PMMA-Cp2TiCl2两种负载型的茂金属催化剂颗粒.通过对二种催化剂颗粒的乙烯淤浆聚合动力学的研究发现,PMMA/PS-Cp2TiCl2催化剂颗粒的聚合反应速度有很大的滞后效应,聚合最大反应速率出现在第9 min,而PS/PMMA-Cp2TiCl2催化剂颗粒动力学行为与Cp2TiCl2催化剂均相聚合相似.     

热塑性树脂浸渍黄麻纤维毡的研究

研究了热塑性树脂PP(聚丙烯)浸渍黄麻纤维毡的速率及相关因素,以解决天然纤维毡增强热塑性复合材料中连续熔融浸渍,考察了浸渍速率、温度等参数对其加工成型及力学性能的影响.用改装的毛细管流变仪作为实验装置,以一维Darcy定律处理实验数据,研究了压力对毡体空隙率以及熔体粘度对浸渍速率的影响.结果显示,相同的压力下,浸渍速率和熔体粘度成反比,麻纤维毡的压缩空隙率都要高于玻璃纤维毡.通过对纤维毡体结构、可压缩性、纤维直径以及毡体渗透率进行对比,进一步讨论了纤维毡浸渍速率的影响因素.表明麻纤维平均直径远大于玻璃纤维,纤维堆叠产生的空隙明显大于玻璃纤维且在麻纤维毡中不存在玻璃纤维毡中的束内浸渍,麻毡的浸渍速率约为玻纤毡的3.5倍,平均渗透率K约为玻纤毡的14倍.运用毛细管模型计算了两种毡体的Kozeny常数,其值分别为2950和442.     

CBT树脂反应特性及其纤维复合材料力学性能的研究

分析了环状对苯二甲酸丁二醇酯(CBT)-CBT100和CBT160两种树脂的反应特性,研究了三种锡类催化剂对CBT100树脂低粘度适用期和高温反应时间的影响,并对比了采用树脂粉末熔融浸渍成型和高温真空辅助灌注成型(VARTM)方法制备的玻璃纤维增强聚环状对苯二甲酸丁二醇酯(PCBT)复合材料的力学性能。研究结果表明,CBT160树脂高温反应速度较快,适合树脂粉末熔融浸渍相类似的成型工艺。CBT100树脂通过外加一定量的单丁基三异辛酸锡或二丁基二月桂酸锡催化剂,可以使其具有合适的适用期和反应聚合时间,适宜用于VARTM过程。含单丁基三异辛酸锡的CBT100树脂通过高温VARTM方法制备的玻纤增强PCBT复合材料的综合力学性能较好,略高于采用CBT160树脂用树脂粉末熔融浸渍成型方法制备的复合材料的力学性能。     

Structural,morphological and magnetic parameters investigation of multiferroic (1-x)Bi2Fe4O9- xCoFe2O4 nanocomposite ceramics

(1-x)Bi₂Fe₄O₉- xCoFe₂O₄ (0.0≤ x ≤1.0) multiferroic nanocomposites were prepared by wet chemical procedures combining reverse chemical co-precipitation and Pechini-type sol–gel techniques followed by mechanical blending process. The XRD and SAED results showed that the diffraction patterns are perfectly indexed to the constituent phases present in composite samples. The crystallite sizes of the constituent phases were 35.4 and 39.4 nm for cobalt and bismuth ferrites, respectively. The characteristic peaks in FT-IR spectra confirmed formation and purity of all specimens. FESEM micrographs revealed the uniform phase distribution with the mean grain size of approximately 40 and 230 nm for CoFe₂O₄ and Bi₂Fe₄O₉, respectively. TEM micrograph indicated suitable distribution in the as-prepared composite sample. The VSM results revealed that saturation and remnant magnetization increase by increasing CFO content in composites. Based on the results obtained from M-H curves, magnetic properties of composites did not originate only from linear combination of parent phases. The recorded coercivity values of all nanocomposites, for example 1443 Oe for x = 0.4 were higher than those of each parent phase i.e. 708 Oe for CoFe₂O₄ and 149 Oe for Bi₂Fe₄O_9, showing a noticeable improvement in magnetic properties.     

Novel self-reinforcing ZrO2–SiO2 aerogels with high mechanical strength and ultralow thermal conductivity

Novel self-reinforcing ZrO₂–SiO₂ aerogels with high mechanical strength and ultralow thermal conductivity are fabricated by impregnating hydrolyzed ZrO₂–SiO₂ sol into wet gel matrix and drying. The ZrO₂–SiO₂ sol fills the macropores and defects of ZrO₂–SiO₂ aerogel matrix generating during the gelation process, which contributes to the improvement of the mechanical properties of the ZrO₂–SiO₂ aerogel matrix. The mechanical and thermal properties of the as-prepared ZrO₂–SiO₂ aerogel are investigated and discussed. The results show that the mechanical strength of the self-reinforcing aerogels obviously increases from 0.51 to 3.11?MPa with the increase of impregnation times, while the thermal conductivity of the aerogels slightly increases from 0.0235 to 0.0306?W?m^?1 K^?1. The novel self-reinforcing ZrO₂–SiO₂ aerogel could have interesting applications in aerospace and energy because of its outstanding mechanical and thermal properties.     

MnO x /ZrO2 催化剂制备及催化臭氧氧化降解甲基橙

以商品化ZrO₂为载体,采用等体积浸渍法制备MnO _x /ZrO₂催化剂,对目标污染物甲基橙溶液进行催化臭氧降解效果研究。比较不同焙烧温度（350、400、500和550℃）、不同MnO _x 负载量（5%、10%、15%和18%）等制备条件对催化剂活性的影响,结果表明：在400℃,MnO _x 负载量为15%时,催化剂对催化臭氧降解甲基橙溶液表现出最好的活性。反应进行60 min后,甲基橙溶液的脱色率达92.8%,较单独臭氧氧化提高了36.1%。催化剂15%MnO _x /ZrO₂（400℃）的酸碱使用范围（pH为2.7、6.5、8.7、10.8）实验表明：甲基橙溶液不同初始pH条件同样会影响催化剂的活性,且pH=2.7时表现出最好的催化效果,甲基橙脱色率可达95%。循环实验表明,15%MnO _x /ZrO₂（400℃）具有较好的稳定性,催化剂循环使用三次后,甲基橙溶液脱色率仍保持在85%以上,且活性组分的流失是降低催化剂活性的一个重要原因。