层状双氢氧化物和蒙脱石的剥离及其自组装

以钙基蒙脱石为原料,氟化钠为钠化剂,十六烷基三甲基溴化铵为有机改性剂采用离子交换法制备了有机蒙脱石(CTA-MMT);以硝酸镁、硝酸铝、氢氧化钠和十二烷基磺酸钠为原料,采用水热法制备了有机型镁铝层状双氢氧化物(Mg Al-SDS-LDH);以氯仿为剥离介质,采用超声法剥离CTA-MMT和MgAl-SDS-LDH,分别获得了两种剥离型矿物溶胶,将其混合自组装制备了蒙脱石/层状双氢氧化物(MMT/LDH)组装材料。用XRD和AFM表征了CTA-MMT和MgAl-SDS-LDH及其剥离产物,并分析了组装材料的热稳定性。结果表明,CTA-MMT和MgAl-SDS-LDH在氯仿介质中剥离仅需20 min,剥离型CTA-MMT和MgAl-SDS-LDH片层平均厚度分别约为9和8 nm。MMT/LDH由剥离型CTA-MMT和MgAl-SDS-LDH片层有序组装而成,组装材料结构与MgAl-SDS-LDH和CTA-MMT的含量有关,其结构单元层间距2.59 nm(CTA-MMT含量较低时)随着组装材料中CTA-MMT含量的升高而转变为1.82 nm。MMT/LDH组装材料具有较单一的CTA-MMT或MgAl-SDS-LDH更高的热稳定性。     

The effect of curing temperature on thermal,physical and mechanical characteristics of two types of adhesives for aerospace structures

The effects of cure temperatures on the thermal, physical and mechanical characteristics of two types of thermosetting structural epoxy film adhesives were determined in detail. The aim of this paper is to assess the effect of cure temperatures (82–121 °C) on the degree of cure of the two adhesives and the relevant void formations that need to be addressed in bonded part production and repair. Two thermal parameters were used to characterize the advancement of the reaction, such as degree of cure and glass transition temperature. The joint properties with respect to the cure temperatures were characterized by void content and bond-line thickness measurements and lap shear strength tests. Experimental results presented that all lap shear strengths were well within minimum shear strength (29 MPa) required by the specification of the film-type adhesive. However, the lap shear strength testing after aging at 82 °C and 95%R.H for 1000 h showed that the improved durability when the adhesive is cured at 121 °C did not occur for the 82 °C cure. Low curing conversion (75–77% degree of cure) combined with high voids (over 2 areal%) has a catastrophic effect on the bonding qualities at the metal-adhesive interface and due to lack of cohesion in the adhesive. The changes in the interface caused by the low temperature curing may contribute to an increased susceptibility of the bonded joint to moisture and consequent bond-line degradation.     

微-纳米无机粒子改性聚丙烯材料的最新进展

综述了近年来微-纳米无机刚性粒子填充改性聚丙烯(PP)材料的最新进展,介绍了微米级、纳米级和微-纳米组合无机刚性粒子的添加对PP复合材料性能的影响。无机刚性粒子越细,越有利于PP材料的增强增韧;无机刚性粒子的表面改性处理对复合材料的微观结构和性能有重要影响。微米无机刚性粒子可提高PP材料的抗冲击强度与刚性,但强度会有所降低;均匀分散的无机纳米粒子同时起到增强增韧的双重作用;具有粒径级的组合粒子的填充改性优于单一无机粒子。     

超细氢氧化镁粉的表面改性

超细活性氢氧化镁是一种重要的环保型阻燃材料。本文通过使用2种钛酸酯（JN-201和JN—101）和1种含H硅油（202）对超细氢氧化镁粉进行了表面改性,通过对改性前后粉体的活化指数来预先评价改性效果。对改性前后粉体进行了SEM、FTIR分析．研究了粉体改性的机理。结果表明．使用钛酸酯JN—101和含H硅油改性可以有效提高粉体的活化指数,而钛酸酯JN-201则不行。SEM和FTIR分析表明．使用钛酸酯JN—101和含H硅油可以提高氢氧化镁粉在干燥状态下的分散性,钛酸酯JN—101与氢氧化镁粉体表面为化学吸附,而含H硅油与氢氧化镁粉体表面为物理吸附。     

超细活性无机复合阻燃填料在PVC中的应用研究

研究了以Al(OH)3、Mg(OH)2、煅烧高岭土、白炭黑为主要组分的超细活性无机复合阻燃填料应用于PVC电缆料的阻燃性能、力学性能和电绝缘性能并与其他无机阻燃填料进行了比较。结果表明：超细活性无机复合阻燃填料应用于软PVC，其力学性能和电性能可达到GB／T 8815-2002标准，氧指数达35．6％，烟密度为174．7。这种超细活性无机复合阻燃填料具有高效阻燃、填充增强和电绝缘性三种功能。     

Methanol Steam Reforming Over NiAl and Ni (M) Al Layered Double Hydroxides (M = Au, Rh, Ir) Derived Catalysts

This paper deals with an experimental investigation concerning steam reforming of methanol at 280, 340 and 380 °C over NiAl and Ni (Au, Rh or Ir)Al layered double hydroxides (LDHs) derived catalysts. Incorporation of noble metal ions into the NiAl-LDH framework was evidenced by XRD, TGA and TEM techniques. High selectivity to H₂ and CO₂ with less than 5% (volume) CO and trace CH₄ was observed over the NiAl-LDH catalyst. Whereas CO and H₂ are major products at lower temperatures after addition of Au, Rh and Ir to the NiAl-LDH system. They are significantly reduced with the concomitant increase in CH₄ and CO₂ as the temperature increased.     

铝材化学镀镍预处理工艺的研究

对铝材化学镀镍技术核心部分,即预处理工艺进行了深入研究.对传统预处理工艺中锌酸盐处理进行了改进,通过正交实验,研制了一种性能优异的中等浓度多元合金化浸锌液,并选择了能与该浸锌处理最佳结合的碱性化学预镀镍配方及工艺条件.     

Raney Ni催化剂的制备及应用研究

Raney-Ni催化剂是一种十分重要的骨架型催化剂,由于其具有的高活性及高选择性,被广泛应用于有机反应。本文简述了Raney Ni催化剂的制备方法,阐述了铝镍合金晶体结构、第三金属、残余铝、活化条件和催化剂粒度对活性的影响,并对Raney Ni催化剂在氢化反应、脱硫、脱卤反应、硝基加氢反应、氨解反应等方面的应用作了概括说明。     

Mullite (3Al2O3·2SiO2)–Aluminum Phosphate (AlPO4), Oxide, Fibrous Monolithic Composites

Mullite–AlPO₄ fibrous monolithic composites were fabricated by a co-extrusion technique using ethylene vinyl acetate (EVA) as a binder. Processing routes such as mixing formulation, extrusion sequence, binder removal cycle, pressing, and sintering procedures are described. An effort to make tougher composites was conducted by modifying the microstructures of the composites. Different kinds of monolithic composites were fabricated by changing the number of filaments, and the composition and thickness of interphase layers, and their microstructural and mechanical properties were characterized. To make the interphase more porous and to facilitate debonding and fiber pullout in the composite, graphite was added as a fugitive "space filler" into the interphase material and then removed. A fibrous monolithic composite with a sintered interphase thickness of 5–10 μm and an interphase composition of 50 vol% graphite and 50 vol% AlPO₄ had a three-point bend strength and a work of fracture of 129 ± 2 MPa and 0.86 ± 0.05 kJ/m², respectively. This corresponded to 42% of the strength but 162% of the work of fracture when compared with the values for a single-phase mullite. Two-layer, mixed 50% two-layer:50% three-layer, and three-layer fibrous monoliths were fabricated and their microstructural and mechanical properties were studied. The difference in the sintering behaviors of the two-layer and three-layer composites is described.     

Er3+:Yb3+:Y3Al5O12单晶中Er3+离子光谱参数的计算

采用提拉法生长出光学质量的Er3 :Yb3 :Y3Al5O12(YAG)单晶,测定了晶体的吸收光谱和上转换荧光光谱,根据Judd-Ofelt理论,计算出Er3 在YAG晶体中的强度参数Ω2=1.074 1×10-20cm2,Ω4=1.295 3×1020cm2,Ω6=0.923 8×1020cm2.由此得到部分波段跃迁的荧光分支比、辐射寿命和积分发射截面积.提出将679 nm波段的4F9/2→4I15/2跃迁作为激光输出进一步研究的新通道.