喷射电沉积块体多孔镍的研究

采用喷射电沉积方法制备块体多孔镍.分别选择不同的扫描方式、电流密度进行试验,分析了各试验参数对块体多孔镍形貌的影响规律,并应用图形处理软件ImageJ对多孔镍的孔隙率和相对密度进行分析,获得最佳试验参数.结果表明:采用扫描速率中间部位慢于边界部位、在块体各点均暂停的扫描方式,有利于多孔镍沉积均匀平整.随着电流密度的增加,镍沉积层明显变得致密,孔径减小,而孔隙率增大.     

喷射速度对喷射电沉积多孔金属镍的影响

借助电化学技术,采用喷射电沉积的方法,直接制备出具有一定厚度、孔隙率较高、组织较均匀的多孔金属镍,并研究了不同喷射速度对喷射电沉积直接制备多孔金属镍的表面形貌和结构特征的影响。研究结果表明,多孔金属镍的孔隙率随喷射速度的增加先减小后增加。     

多孔金属连续电沉积数学模型

采用电沉积方法制备连续多孔金属,通过把电流密度随时间的变化转换为镀区内的位置分布,建立了稳恒状态下高孔率带状多孔金属连续电沉积动态模型,推导出表观电流密度分布的数学表达式.并在多孔金属镍实际制备过程中对模型进行了验证,结果表明带状多孔金属与阳极配置满足一定角度时,实现阴极表观电流密度恒定,镍的结晶细致.这一工作为电沉积法制备多孔金属的在线控制提供了理论依据.     

硼砂对粉煤灰多孔玻璃结构及性能的影响

选用粉煤灰和碎玻璃为基础原料,以碳酸钙为发泡剂,采用粉末烧结法制备多孔玻璃.采用SEM对试样微观形貌进行表征,并对成品表观密度、抗压强度、孔隙率等性能进行测定,研究添加剂硼砂对多孔玻璃孔径及其分布、孔隙率和性能的影响.实验结果表明,硼砂的添加起到了明显的助熔作用,并稳定了多孔玻璃孔径分布,且硼砂添加量为3.5%时效果较好,孔径分布均匀,孔隙率为48%左右.     

氨基磺酸盐体系制备多孔镍

采用氨基磺酸盐体系在碳骨架上制备了多孔镍。观察了多孔镍的表面形貌和断口形貌,并测试了多孔镍的孔隙率和压缩性能。结果表明:原始碳骨架的孔隙率为93.0%,经过电沉积之后孔隙率减小了6.0%～11.2%;氨基磺酸盐体系所得多孔镍的最高抗压强度是硫酸盐体系所得多孔镍的最高抗压强度的9.37倍;氨基磺酸盐体系所得多孔镍断口为三角形断口,断口镀层较厚且均匀,镀层中间未见裂纹。     

分形结构二维金属镍枝晶的制备与分析

以环形金属镍为阳极,石墨芯为阴极,利用点电极电沉积法制备了具有明显分形结构的二维金属镍枝晶;再以平行板金属镍为阳极,石墨板为阴极,用自行设计的试验设备,通过喷射电沉积法制备了准二维金属镍枝晶簇。采用计算机软件,求得点电极电沉积和平行板电极喷射电沉积所得沉积物的分形维数分别为1.556387和1.753856。两种电沉积方法都适用于金属枝晶的研究。点电极电沉积过程中,电流随时间的延长而逐渐增大;平行板电极喷射电沉积过程中,电压随时间的延长而逐渐降低。     

沉积温度对碳/碳复合材料密度均匀性的影响

采用快速化学液相气化渗透法制备了二维碳／碳复合材料。用Leica定量金相分析仪及Archimedes排水法测定了不同沉积温度制备的样品沿径向的孔隙率及密度分布，同时用扫描电子显微镜观察了样品的低倍形貌及孔隙率分布。实验结果表明：定量金相观察计算得到的孔隙率值略大于排水法测得的孔隙率值；当沉积温度≤1200℃，随着沉积温度的升高，沉积得到的材料残留孔隙率降低，密度升高，样品沿径向密度分布比较均匀，基本上不存在密度梯度或分布不均匀现象。沉积温度为1250℃时，孔隙分布也比较均匀，但样品内残留孔隙较多且大。     

金属镍电沉积中枝晶分形生长的研究

将分形几何与电化学原理相结合,通过改进的有限扩散凝聚模型(diffusion-limited aggregation,DLA),采用基于Microsoft Visual C 6.0的Open GL编程,对点电极为阴极进行二维电沉积时沉积产物的形貌进行了模拟.以环形金属镍为阳极,石墨为阴极,用自行设计的试验设备制备了二维的金属镍枝晶以验证模拟结果.结果表明,在保持电压恒定的条件下,镍沉积层的形貌特征为具有分形结构的枝晶,这与采用DLA模型模拟所得的二维枝晶形貌具有相似性,表明该模型对枝晶电沉积的实验研究具有很好的指导意义.     

多孔铜电极催化CO_2合成碳酸二甲酯的研究

采用氢气泡模板法制备了多孔铜作为电催化还原CO_2的电极材料。通过控制电镀时间、电镀液中十六烷基三甲基溴化铵(CTAB)的浓度及HCl的加入量实现了电极活性层厚度、孔径、孔隙率以及微观形貌的有效调节,并研究了其对CO_2电催化还原活性的影响。结果表明,电极层多孔铜厚度、孔径大小以及孔隙率对电极的催化活性有一定的影响,而多孔的形貌不是影响电极催化活性的关键因素。当电沉积时间为20 s、CTAB的加入量为10 mmol/L时,得到的孔隙率为60.261%的多孔铜电极具有最佳的CO_2电催化还原活性;将得到的多孔铜电极用于合成碳酸二甲酯(DMC),优化了DMC的合成反应温度及电还原电位。DMC产率在最优条件下可达到84%。     

多孔铜电极催化CO_2合成碳酸二甲酯的研究

采用氢气泡模板法制备了多孔铜作为电催化还原CO_2的电极材料。通过控制电镀时间、电镀液中十六烷基三甲基溴化铵(CTAB)的浓度及HCl的加入量实现了电极活性层厚度、孔径、孔隙率以及微观形貌的有效调节,并研究了其对CO_2电催化还原活性的影响。结果表明,电极层多孔铜厚度、孔径大小以及孔隙率对电极的催化活性有一定的影响,而多孔的形貌不是影响电极催化活性的关键因素。当电沉积时间为20 s、CTAB的加入量为10 mmol/L时,得到的孔隙率为60.261%的多孔铜电极具有最佳的CO_2电催化还原活性;将得到的多孔铜电极用于合成碳酸二甲酯(DMC),优化了DMC的合成反应温度及电还原电位。DMC产率在最优条件下可达到84%。     

基于泡沫金属的复合毛细芯的物性测试

为改进毛细芯的传热传质性能，以泡沫金属铜或镍为骨架，在其内部填充树形金属铜粉或镍粉，通过树形金属粉末调控泡沫金属内的孔隙结构及孔径分布，制备出一种以金属泡沫为基底的复合毛细芯，并对制备的复合毛细芯的孔隙率、抽吸性能、有效热导率及蒸发率进行研究。结果表明，这种结构的复合毛细芯孔隙率较高，有效热导率为4.1?9.8 W/(m?K)。从毛细芯毛细抽吸、有效热导率和蒸发率综合来看，以金属泡沫镍为骨架、树形镍粉末与造孔剂质量比为5:5的复合毛细芯性能最好。     

Synthesis of Biomorphous Nickel Oxide from a Pinewood Template and Investigation on a Hierarchical Porous Structure

The hydrothermal synthesis of biomorphous nickel oxide (NiO) with pine template and nickel nitrate precursor is reported here. The morphology, porosity and connectivity of porous products in different length scales were characterized by field emission scanning electron microscopy, X-ray diffraction and nitrogen adsorption measurements. Their porous structures were found to be hierarchical from 1 up to 25 μm (in micrometer scale) and from 2 nm to 60 nm (in nanometer scale). Furthermore, depending on the heat-treatment temperatures, the porosity of the pine-templated NiO can be designed.     

Preparation and characterization of porous ceramics from nickel smelting slag and metakaolin

Porous ceramics with high porosity and low bulk density were prepared by using nickel slag and metakaolin as the primary raw materials, glass powder as flux, and SiC as the foaming agent. The content of nickel slag and foaming agent had a significant effect on the bulk density, porosity, and flexural strength of the porous ceramics. The porous ceramics with the best properties were obtained at 1100 °C for 30 min with 50 wt% nickel slag, 40 wt% metakaolin, 10 wt% waste glass, and 0.8 wt% SiC. It had a low bulk density (as low as 245 kg/m³), high flexural strength and compressive strength (0.6 MPa and 1.17 MPa, respectively), and high porosity (about 89.8%). The nickel slag was magnetically separated as well. The density of nickel slag powder could be reduced via magnetic separation, and there was no significant change in the crystal structure of the raw material. Compared with porous ceramics prepared using nickel slag without magnetic separation, ceramics subjected to magnetic separation had lower bulk density, higher porosity, and the same phase composition. This study can be used as an indicator for the application of nickel slag in porous ceramics, which is of great significance in providing a great substitute nickel slag towards recovery and utilization.     

多孔材料对氢气爆轰的抑制作用

为了研究多孔材料对氢气爆轰的抑制作用,在内径80 mm、长6000 mm的爆轰圆管中开展2H₂+O₂+3Ar预混气爆轰传播实验。在距点火头5000 mm处放置不同孔隙密度(10、20、40 ppi)厚度30 mm的Al₂O₃泡沫陶瓷和不同厚度(10、30、50 mm)孔隙密度20 ppi的泡沫铁镍金属,分别使用压力传感器、烟膜记录爆轰波压力、胞格结构,计算爆轰波传播速度。结果表明,速度亏损和胞格尺寸随着孔隙密度或厚度的增加而增大,但是均与初始压力成反比。两种多孔材料的材料特性不同,泡沫铁镍金属具有良好的导热性,因此对爆轰波的抑制效果强于Al₂O₃泡沫陶瓷。     

Characterization of porous bi-modal Ni structures

A new nickel-based porous structure, exhibiting a bi-modal pore size distribution, has been developed through the combination of nickel foam (INCOFOAM) with sintered nickel filamentary powder (T255). Sintering was carried out in the 900–980 °C temperature range in a vacuum environment. These bi-modal nickel samples were examined for their microstructure, hydraulic behaviour including capillary head and permeability, specific surface area (SAA), and overall porosity. The incorporation of a layer of sintered nickel filamentary powder (T255) onto the nickel foam was shown to increase both the specific surface area and capillary pumping pressure of the foam, while simultaneously maintaining high porosity and liquid permeability. Both the sintering temperature and the degree of nickel powder coverage were determined to be critical factors contributing to the properties of these bi-modal nickel porous structures.     

Preparation and properties of porous ceramics from nickel slag by aerogel gelcasting

To further resource industrial solid waste, porous ceramics with high porosity were prepared by a gelcasting method using nickel slag and kaolin as raw materials and hydrophilic nontoxic SiO₂ aerogel as a gelling agent. The effects of nickel slag content, dispersant and solid content on the properties and microstructure of porous ceramics were investigated in detail in terms of density, compressive strength, porosity, phase composition and micromorphology. The results confirmed that a certain amount of nickel slag can effectively improve the porosity of porous ceramics, while the addition of dispersant can promote the flow of the slurry, enhanced the denseness of the raw billet and significantly improved the compressive strength. However, its excessive use had a negative effect on the ceramic density and porosity. At the same time, the solid content played a key role in the performance of porous ceramics prepared by gelcasting, and too much solid content was also not conducive to the generation of pores. When the nickel slag content was 55%, the amount of dispersant was 2%, and the solid content was 60 vol%, the porous ceramic had a better overall performance, the density of the porous ceramic was 510 kg/m³, the compressive strength was 1.3 MPa, and the porosity reached 80.1%. The major crystalline phases of porous ceramics prepared by nickel slag were cordierite and anorthite.     

Synthesis of hierarchical porous ZnO microspheres and its photocatalytic deNOx activity

Hierarchical porous metal oxide nanostructures have currently attracted much interest because their unique structures with large surface area, high porosity and low density are greatly valuable for functional applications in catalysis, biological engineering and photoelectronics device. Herein, hierarchical porous ZnO microspheres were fabricated by a facile hydrothermal method with subsequent calcination. The sample morphology has been characterized by scanning electron microscopy and transmission electron microscopy. The powder X-ray diffraction has also been used to determine the crystalline structure of the synthesized materials. The effect of calcination temperature on the crystalline structure of synthesized nanostructures has been systematically investigated. The photocatalytic activities of the obtained samples have been evaluated by means of photocatalytic decomposition of nitrogen monoxide (NO).     

石墨基浸金属多孔材料微观孔隙结构及其分形特征

为定量描述石墨基浸渍金属材料的孔隙结构特征并研究其对浸渍过程的影响规律,在石墨基多孔材料孔隙形成机理研究的基础上,分析形成浸不透孔洞的原因,并运用分形理论对孔隙结构特征进行了描述. 研究表明,石墨基浸渍金属多孔材料的孔隙结构具有典型的分形特征,其基体、孔隙、浸渍金属分形维数分别为1.80~1.85, 1.55~1.65, 1.50~1.55,未浸渍区域的分形维数为1.42~1.60,孔隙率为17.25%~24.85%. 分形维数反映了孔隙结构的非均质性,与采用压汞实验获得的孔隙率变化规律有较好的一致性,证明可用分形维数表征石墨基浸金属材料的孔隙率.     

用冰模板法制备定向结构氧化锆多孔陶瓷

以冰为造孔模板制备氧化锆多孔陶瓷。采用扫描电镜观察微观结构,并测量其气孔率和体积密度。结果表明:经过冷冻干燥工艺及高温烧结后,获得了定向排列的多孔结构。多孔陶瓷的气孔率为29.09%,体积密度为1.37g/cm3。     

Fabrication of highly porous biodegradable monoliths strengthened by graphene oxide and their adsorption of metal ions

Ordered porous chitosan–gelatin/graphene oxide (CGGO) monoliths with over 97% porosity were prepared by a unidirectional freeze-drying method and used as adsorbents for metal ions. They were characterized by X-ray diffraction, scanning electron microscopy and thermogravimetric analysis. In addition, their water absorption, wet-state stability and compressive strength were measured. The adsorption behavior of the CGGO monoliths and influencing factors such as pH, graphene oxide (GO) concentration, metal ion concentration as well as the effect of ethylenediaminetetraacetic acid (EDTA) were investigated. The incorporation of GO significantly increased the compressive strength of the CGGO monoliths in both their wet and dry states, and changed their porous structure. They exhibited an extremely high adsorbing ability for metal ions, which decreased at low pH, but increased from 20% to 88% upon the addition of EDTA at low pH. The CGGO monoliths have good stability and can be recycled several times with only a slight loss in adsorption ability. In addition, they are biodegradable, non-toxic, efficient and regenerable.