超临界法制备(CeZrLaPr)O稀土汽车尾气催化剂的研究

以CeZrLaPr氢氧化物为前驱体,经乙醇洗涤置换成醇凝胶。CeZrLaPr氢氧化物在乙醇溶剂中,当温度和压力超过乙醇临界点(243℃,6.4 MPa)时,氢氧化物脱水、晶化和干燥3个过程一步完成,制得粒径5 nm、具有高储氧能力(OSC)的(CeZrLaPr)O稀土汽车尾气催化剂,并可实现规模化生产。     

微乳液聚合物纳米粒子的研究方法

综述了微乳液聚合制备聚合物纳米粒子的研究内容及方法.其主要的研究内容包括:聚合物纳米粒子的化学组成及结构、形态、分子量及分布、热行为以及聚合物纳米粒子的性能等.研究方法有红外光谱、核磁共振、透射电镜、凝胶渗透色谱法、粘度法和光散射等.最后,展望了新型表征手段以及微乳液聚合两个领域的交叉发展.     

纳米镍粉在钛合金-不锈钢扩散焊接中的应用

采用恒温恒压扩散焊、相变超塑性扩散焊、冲击加压扩散焊对直接对焊和加纳米镍粉中间层的钛合金-不锈钢焊接接头进行了研究。测试了接头强度,并进行了断口形貌观察和组织分析,结果表明：3种试验方法中,恒温恒压扩散焊所得接头强度较小,而冲击加压扩散焊所得接头强度较高;直接扩散焊时,接头上两种基体材料之间的互扩散程度很大程度上影响了钛合金-不锈钢接头的强度;采用纳米镍粉作中间层能形成强度较高的接头,达到了213MPa、但纳米镍粉的致密度不够高,接头的强度在很大程度上受到了限制。     

凝胶自蔓延燃烧法制备纳米La_2O_2CO_3粉体

研究一种以溶胶-凝胶作为前躯体制备纳米La2O2CO3粉体的新方法,以柠檬酸和硝酸镧为原料,采用凝胶自蔓延燃烧法制备纳米La2O2CO3粉体,并利用X射线衍射、差热分析、透射电镜等手段对合成产物进行表征,确定最佳的工艺条件。结果表明:在前驱溶液的pH值为2,烘干温度为400℃,煅烧温度为600℃时,可以制备出平均晶粒尺寸为30 nm的La2O2CO3颗粒,且粉体的粒径均匀,粒径分布狭窄。     

Investigation of self-assembly growth and thermal stability of Au nano-particles on atomic-layer-deposited Al2O3 film

在原子层淀积的Al₂O₃薄膜表面自组装生长Au纳米颗粒,研究了Au纳米颗粒的自组装过程和热稳定性. 结果表明,原子层淀积的Al₂O₃薄膜表面很容易吸附氨丙基三甲基硅烷(APTMS), 有利于Au纳米颗粒的自组装, 生长出的Au纳米颗粒尺寸为5--8 nm, 密度约为4×10¹¹cm^-2. 在300℃氮气中退火使Au纳米颗粒的尺寸增大, 但是没有改变APTMS的吸附状态和Au的化学组成. 当退火温度提高到450℃时, Au纳米颗粒发生明显的团聚, 且分布变得极不均匀.     

采用一种高能搅拌磨湿法制备纳米氧化铝粉体

研究用一种先进的高效能搅拌磨湿法制备纳米粒级的氧化铝(α-Al2O3)粉体。采用氮气吸附法测量不同研磨颗粒产品的比表面积,采用X射线沉降粒度仪、电超声粒度分析仪和扫描电镜测定和观察颗粒的粒径和形貌,采用X射线衍射法(XRD)进行晶形分析。结果表明,微米级给料在湿法研磨数小时后可得到一种平均粒径为70 nm和比表面积大于115 m2/g的纳米颗粒产品。经研磨α-Al2O3颗粒的晶体各主晶面均遭到不同程度破坏,但晶相仍为α相。另外,还发现,研磨过程中研磨氧化铝颗粒所需比能耗随着研磨时间的延长而增加,而能量利用效率迅速降低。     

颗粒含量对含污染物油润滑条件下纳米复合电刷镀层摩擦学性能的影响

研究了电刷镀液中纳米Al₂O₃颗粒含量对复合镀层中纳米颗粒含量、镀层表面形貌、显微硬度以及摩擦学性能的影响。结果表明,随着镀液中纳米Al₂O₃颗粒含量的增加,镀层组织细化,显微硬度提高,镀层在含细沙油润滑条件下的耐磨性比不加纳米颗粒的快速镍镀层提高了80％。当镀液中Al₂O₃含量为20 g/L时,镀层具有最佳的耐磨性,进一步提高镀液中的纳米颗粒含量,镀层性能反而下降。      

Comparison of PVDF porous membranes modified by two different methods using composite nano-particles

To improve the hydrophilicity and anti-fouling performance in water treatment,both entrapped method and deposited method were used to modify polyvinylidene fluoride(PVDF)porous membrane with composite Al2O3/TiO2 nano-particles.Neat PVDF membrane was prepared and its property was also compared with that of the modified membranes.Membrane permeation flux and anti-fouling performance were measured using a membrane cell.The contact angle between water and membrane surface was detected in order to denote the membrane hydrophilicity.Membrane morphology and surface structure were examined by atomic-force microscopy(AFM)and scanning electron microscopy(SEM).Experimental results showed that modified membranes had higher permeation fluxes than that of the neat PVDF membrane.The addition of nano-particles altered membrane surface morphology and increased surface roughness.Due to the hydrophilicity of nano-particles,however,the membrane anti-fouling performance was improved instead of worsened.The entrapped membrane exhibited better anti-fouling performance than the deposited membrane and the neat membrane.     

异种搅拌摩擦焊制备铜铝合金双金属纳米复合材料

对纯铜与AA5754合金进行对接搅拌摩擦焊接.为了降低金属间化合物的有害影响,在搅拌摩擦焊(FSW)接头中添加纳米SiC强化颗粒.采用拉伸试验、显微硬度试验、扫描电镜和X射线衍射分析方法研究焊接接头的性能.结果显示,当焊接速度为50 mm/min、转速为1000 r/min时接头的性能最好.纳米SiC颗粒的存在使搅拌区...     

Degeneration and rejuvenation of shape memory effect associated with the precipitation of coherent nano-particles in a Co-Ni-Si shape memory alloy

In a solution treated Co-20Ni-6Si shape memory alloy,coherent nano-particles were precipitated after annealing at 873 K for 1 min,but the shape memory effect almost vanished.It is attributed to that the coherent nano-particles not only suppressed the stress-induced face-centered cubic to close-packed hexagonal martensite transformation but also damaged the crystallographic reversibility of reverse martensite transformation.After further annealing at 1073 K for 1 min,the shape memory effect was reju-venated owing to the dissolution of nano-particles.Besides,the recovery strain significantly increased to 5.1％ from the solution treatment of 3.1％ after annealing at 1073 K for 1 min.