共查询到19条相似文献,搜索用时 78 毫秒
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采用液相沉淀法以AlCl3·6H2O,MgCl2·6H2O,Na2CO3,NaOH为原料,制备镁铝水滑石。研究结果表明水浴70、80、90℃加热时均能制备出纯净的镁铝水滑石,从热重分析可知镁铝水滑石有两个失重阶段,第一次热分解起始点约为173℃失重约15%,释放出镁铝水滑石中间层的4个结晶水,第二次热分解起始点约为352℃失重约30%,中间层中的碳酸根离子以二氧化碳的形式放出,同时羟基分解产生水。镁铝水滑石晶粒呈不规则的六边形,晶粒大小约在为30~70nm之间。 相似文献
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采用共沉淀法合成了不同摩尔投料比的NiMgAl类水滑石化合物.测定了Ni、Mg、Al单盐以及不同摩尔比的混合硝酸盐溶液的滴定曲线,考察了加料方式、晶化温度、晶化时间、原料配比对类水滑石合成的影响.通过XRD、IR对合成物进行表征,结果表明,在恒定pH值为8~9,n(Mg Ni)/n(Al)=1~3,n(Mg)/n(Ni)=8~16,晶化温度为65℃,晶化时间6h的条件下即得到晶相单=的NiMgAl-HTLcs;随n(Mg Ni)/n(Al)的增加,类水滑石结构的规整性提高,n(Mg)/n(Ni)比增加,层间距略有减小. 相似文献
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通过共沉淀法制备了Mg/Al物质的量比为3∶1的镁铝水滑石,并将其作为载体负载磺化酞菁钴制得新型功能材料酞菁钴负载水滑石(CoPcTs-LDH)。通过红外和热重分析表征了CoPcTs-LDH,研究了CoPcTs-LDH/H2O2对100mL 10mg/L甲基橙的氧化脱色。实验结果表明,在25~37℃、pH值为3~9、反应7h后甲基橙的剩余率均低于30%;反应过程符合一级动力学模型,阿伦尼乌斯活化能Ea=57.64kJ/mol;反应过程中羟基自由基发挥了重要作用;CoPcTs-LDH在重复使用5次后对甲基橙仍有很好的氧化脱色能力,具有较高的重复使用性能。 相似文献
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液相法合成针状镁铝水滑石纳米晶的研究 总被引:13,自引:0,他引:13
研究了合成条件(原料种类、加料次序、NaOH浓度和合成温度)对液相法制备镁铝水滑石试样的相组成的影响.以MgCl2为镁源、NaAlO2为铝源、NaCO3和NaOH为沉淀剂,在常压下采用液相法制备了长度约100nm、直径约10nm的Mg6Al2(OH)16CO3-4H2O针状纳米晶体.并且发现:可溶性原料的选取、最后加入MgCl2的加料次序、>45℃的合成温度和保证反应溶液的pH>12,是瞬间生成镁铝水滑石纳米晶的充分必要条件.提出镁铝水滑石纳米晶核形成的过程是:均匀分布于溶液中的Al13(OH)327+迅速吸附于带羟基OH-的无定型态的Mg(OH)2表面,并进行Al3+扩散,为平衡电价,CO32-也扩散进入Mg(OH)2,从而在瞬间完成镁铝水滑石晶核的形成. 相似文献
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纳米镁铝水滑石的制备及其对聚氨酯阻燃性能的影响 总被引:3,自引:0,他引:3
采用液相沉淀法制备纳米镁铝水滑石微粉,利用XRD、TEM和TG对试样进行表征,研究了反应温度、干燥时间以及碳酸根浓度对镁铝水滑石纳米晶的影响.镁铝水滑石微粉经硅烷偶联剂KH550表面改性后填充到聚醚多元醇组合料中,采用原位聚合法制备出镁铝水滑石/软质聚氨酯纳米复合材料,研究了纳米镁铝水滑石对聚氨酯的阻燃效果及阻燃机理,并与Al(OH)_3阻燃效果进行对比.实验结果表明,晶粒尺寸随反应温度的升高而增大;干燥5h镁铝水滑石的热分解性能较好;适当提高碳酸根浓度可以改善镁铝水滑石晶体规整度;硅烷偶联剂KH550用量为5%时对镁铝水滑石表面改性效果最好;镁铝水滑石阻燃剂填充软质聚氨酯复合体系的阻燃效果要优于Al(OH)_3阻燃剂. 相似文献
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采用溶液共沉淀法合成了CoAl-HT和MgAl-HT水滑石,在800℃下煅烧4h得到了钴铝和镁铝尖晶石氧化物粉体。利用XRD、FT-IR和TG对水滑石及其氧化物粉体的结构和热稳定性能进行了表征分析。从XRD和FT-IR分析结果可知,所得产品为层板水滑石物质,且结晶性良好,从CoAl-HT和MgAl-HT结果对比可知,镁铝组合更容易形成水滑石结构;由氧化物粉体的XRD分析结果可知,在800℃下两者都形成了尖晶石结构,且钴铝氧化粉体尖晶石无杂相,结晶性更好;TG曲线呈现了两个样品的水滑石热学性能,通过对比可知,MgAl-HT在216和372℃下分解而CoAl-HT在197和243℃下分解说明MgAl-HT比CoAl-HT具有更好的热稳定性能。 相似文献
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以Mg(NO3)2.6H2O、Al(NO3)3.9H2O为原料,Na2CO3、NaOH为沉淀剂,采用化学共沉淀法制得MgAl2O4尖晶石前驱体。用TG、XRD、TEM及物理吸附仪研究了试样的热稳定性、物相组成、显微形貌和表面性能。结果表明:前驱体经800℃处理后,几乎全部转变成粒径为10nm左右的MgAl2O4尖晶石超细粉末,并且颗粒分散性好,比表面积大,为136.35m2/g,比传统制备镁铝尖晶石粉末的温度低600~700℃。 相似文献
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M. L. Valcheva-Traykova N. P. Davidova A. H. Weiss 《Journal of Materials Science》1993,28(8):2157-2162
The effect of by-products obtained during the low-temperature synthesis of Mg, Al- hydrotalcite on further thermal decomposition of hydrotalcite material was studied by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy and infrared spectroscopy. By-products, which thermally decomposed below 450°C, led to the formation of -Al2O3 and MgO; by-products which completely decomposed above 500°C resulted in the formation of MgAl2O4 and a sharp increase in MgO dispersity. 相似文献
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超声波对镁合金镁铝水滑石膜耐蚀性的影响 总被引:1,自引:0,他引:1
《功能材料》2015,(20)
将超声波用于镁合金表面镁铝水滑石膜(Mg6Al2(OH)16CO3·4H2O)的制备,研究了超声波功率、频率对膜层结构及耐蚀性的影响规律。通过扫描电镜(SEM)和X射线衍射(XRD)分析了膜层的表面形貌和成分,利用极化曲线和交流阻抗(EIS)评价了该转化膜的耐蚀性。研究结果表明,超声辅助处理工艺能够有效地加快膜层形成,随着超声波频率和功率的提高,成膜速度提高,但过高的功率和频率会导致膜层质量的恶化,在频率为80kHz、功率为100 W条件下制得的膜层较厚且完整,耐蚀性明显优于镁合金基体,腐蚀电流密度约为镁合金基体的1/20。 相似文献
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The transformation of methane into C2 hydrocarbons over thermally degraded Mg, Pb, Al-hydrotalcite material proceeds with the active participation of -PbO. The conditions of pre-treatment leading -PbO formation in the catalyst have been examined on the Pb, Al-hydrotalcite material as a model system. By use of X-ray diffraction, scanning electron microscopy, transmission electron microscopy, infrared spectroscopy and diffusereflectance spectroscopy techniques, it was found that the temperature interval 600–750 °C is optimal for -PbO crystallization. On the basis of the present and previous results, the formation of all components of the catalytically active thermally degraded Mg, Pb, Al-hydrotalcite material, has been explained. During calcination of the Mg, Pb, Al-hydrotalcite material, the lead-containing components form -PbO and -Al2O3 and the magnesium-containing components transform to a finely dispersed MgO-Al2O3 matrix. 相似文献
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《材料科学技术学报》2019,35(8):1629-1635
Due to the excellent mechanical properties of high entropy alloys (HEAs), they have attracted wide attention of materials researchers, but their functional properties have rarely been reported. In order to study the functional properties of HEAs, the decoloration of azo dye Direct Blue 6 (DB6) using equiatomic AlCrFeMn and AlCrFeMnM (M = Mg, Ti, Ni) HEAs synthesized by mechanical alloying was reported in this work. The decoloration rate of DB6 by ball-milled (BM) AlCrFeMn was about 3 times faster than that of by BM MgZn-based amorphous alloy, which was the best one reported in the metallic glasses so far. In order to further improve the decoloration efficiency, we considered adding the fifth elements (Mg or Ti or Ni) to AlCrFeMn. Both of Mg and Ti could improve the decoloration performance of AlCrFeMn, but Ni played a negative role. The reaction activity of AlCrFeMnMg and AlCrFeMnTi was more than 2 and 1.2 times faster than that of AlCrFeMn. The effects of initial pH, temperatures and dye concentration on the decoloration efficiency of AlCrFeMnMg during reactions were systematically investigated. The reaction activity of AlCrFeMnMg in alkaline and acidic azo dye solution was about 37.5 and 16.6 times faster than that of neutral solution, respectively. This work had implications in reaching an attractive, low cost and efficient method for functional applications of HEAs. 相似文献
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Min-Seok Park C. U. Jung J. Y. Kim Kyung-Hee Kim B. W. Kang Sung-Ik Lee 《Journal of Low Temperature Physics》2003,131(5-6):1165-1173
The effect of aluminum substitution on superconductivity in Mg11B2 prepared under a high pressure (HP) of P3 GPa was compared with that in (Mg1–x
Al
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)B2 prepared at ambient pressure (AP). In both the HP and the AP samples, the superconducting transition temperature (T
c) tended to decrease in the same way due to the substitution, but the width of the superconducting transition (90%–10%), T
c, decreased more drastically in the HP sample (HPS) than it did in the AP sample (APS). Moreover, bulk superconductivity lasted up to x=0.3 for the HPS, which is not the case for the APS. A systematic change in the lattice constants due to the substitution of Al for Mg was observed by X-ray diffraction. A scanning electron microscopic image showed that the grains were compactly connected in the HPS, thus explaining the reduced normal-state resistivity. 相似文献
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