无机多孔材料保水性能与其粒度分布分形维数关系的研究

为研究无机多孔材料保水性能与其粒度分布分形特征之间的关系,以4种无机多孔材料为研究对象.采用高温保水法测量了无机多孔材料的保水性能,并运用数字显微系统测定了其粒度分形维数.结果表明,多孔材料的粒度分布分形维数值介于1.1278～2.0523之间,且分形拟合曲线相关系数大于0.99,强的相关性说明多孔材料的粒度分布具有显著的分形特征,多孔材料的保水性能与其粒度分布分形维教呈负相关关系.     

多孔材料孔结构分形维数的研究现状

分形表征是多孔材料孔结构表征中的一种新兴的方法。通过构造分形几何模型，阐述了多孔材料孔结构分形表征中不同类型的分形维数。分析了现阶段研究中存在的问题，探讨了分形表征在多孔材料孔结构表征中未来的发展趋势。     

SiC颗粒增强铝基复合材料切削表面分形维数及其与抗磨损性能的关系

做为一种耐磨性能很好的材料 ,SiC颗粒增强铝基复合材料切削加工表面具有分形特征。实际研究表明SiC颗粒增强铝基复合材料切削加工表面分形维数与抗磨损性能有密切关系 ,本文还分析了表面分形维数越大其抗磨损性能越强的机理。     

粉碎能耗与粒度分布指数的相关性

利用分形和分维数基本概念,导出粉粒度分布的分维数和分裂比、粉碎概率互相存在的简单关系,从能耗与颗粒表面分维数相关出发,推出单位体积粉碎能耗与粒度分布的值指数的相关性;同时推出单位体积粉碎能耗的分维数.当粉碎粒度分布的分维数近似小于0.89时,粉碎能耗呈现自然分形的特征.     

SiC颗粒增强铝基复合材料切削表面分形维数及其与抗磨损性能的关系

做为一种耐磨性能很好的材料，SiC颗粒增强铝基复合材料切削加工表面具有分形特征，实际研究表明SiC颗粒增强铝基复合材料切削加工表面分形数与抗磨损性能有密切关系，本文还分析了表面分形维数越大其抗磨损性能越强的机理。     

颗粒表面分维与其形状指数关系研究

构建了颗粒物表面分维测算模型,研究了颗粒投影轮廓大小与形状指数F的关系。研究表明:颗粒投影轮廓大小与形状指数F具有良好的线性相关性。文中还利用所构建的颗粒物表面分维模型测量了6种碳黑颗粒的表面分维,初步研究了颗粒物表面分维与形状指数F之间的关系,分析结果发现:随着颗粒表面分维的增加,其形状指数F也相应增加,二者具有良好的相关关系。因此,表面分维与形状指数F均可作为颗粒物形状的定量表征,且二者具有良好的相关性。     

泡沫铝微结构的分形特及与子L隙率的关系研究

采用分形理论对泡沫铝材料微结构进行了研究,利用面积周长分维算法证明了其微结构在一定尺度内具有自相似性的分形特征.利用Siterpinski地毯模型研究了包沫铝孔隙率与分维之间的关系.研究结果表明.引入分形维数的分析模型能够较好地反映泡沫铝微结构与孔隙率之间的关系.     

孔径分布对多孔镍孔体积分形维数的影响

用压汞法对用粉末冶金法制备的多孔镍试件进行了测试,得到了多孔镍试件的孔隙率及孔径分布曲线,并以Menger海绵体模型为基础,根据压汞实验数据确定了多孔镍试件的孔体积分形维数,发现多孔镍的孔隙结构具有明显的分形特征,分形维数在2.8～3.0之间.孔径分布范围越宽、平均孔径越大,孔体积分形维数越大.多孔镍的孔体积分形维数在一定程度上反映了多孔镍孔隙结构的均匀性及填充能力.     

粉体粒度分布的分形特征

应用分形几何理论，研究了粉体的粒度分布特征，发现在双对数坐标下，许多材料粒径的重量积百分含量与粒长之间呈直线关系。表明其粒度分布具有分形结构，分维可作为粒度分布特征的一个序参量，它反映了粉体颗粒的粗细程度和集中、均匀特性。     

准分子激光加工表面微观形貌的分维表征研究

准分子激光加工表面的分形特征的研究未见有报道，文章论述了准分子激光加工的表面可以是分形表面，计算了准分子激光加工某些陶瓷表面轮廓的分维D，并把表面分维Ds与Da值和均方根σ值进行了对照，指出了它们之间的对应关系由它们各自的定义所决定。     

储能陶粒填充石膏材料中颗粒分布分形及其对导热性能的影响

应用分形理论考察5种储能陶粒样品的粒度分布分形特征,结合灰色关联分析方法研究储能陶粒的粒度分布分形维对石膏板导热系数的影响。结果表明:各储能陶粒样品的体积累积频率和粒径与最大粒径比值的双对数值呈线形关系,相关系数均在0.95～0.98之间,强的相关表明各储能陶粒样品的粒度分布的分形结构是客观的;而且,随着温度的升高,粒度分布分形维对导热系数的影响逐渐减弱。     

Fractal dimension of the surface of porous ceramic materials

The fractal dimension D of the surface of porous ceramic materials has been determined. The dependence of D on the total porous space volume exhibits two bending points, which reflects a change in the character of porosity on the passage from isolated pores to connected pore clusters and to very large pores with smooth boundaries. This behavior reveals a correlation between the fractal dimension and some well-known features in the properties of porous solids.     

大气颗粒物显微轮廓分形与源解析

为监测大气颗粒物的来源,根据静电吸附原理设计大气颗粒收集装置采集大气颗粒物,通过光学显微放大技术和图像分析方法,得到源颗粒的轮廓分形维数值,结合采样点周边的实际情况,分析和对比各源颗粒的轮廓分形维数值,确定颗粒部分来源;并采用偏光显微镜观察各源颗粒的偏光特征,协同确定大气颗粒的具体来源。结果表明,大气颗粒具有分形特征,其很多特性均与其分形特征有关;采用大气颗粒的轮廓曲线分形维数值作为降尘颗粒来源的辨析参数是可行的,轮廓曲线的分形维数值能很好地表达颗粒的结构形态,特定颗粒源的分形维数值具有一定的范围;将轮廓曲线的分形维数值与各源颗粒的偏光特征相结合,对颗粒来源的辨识准确率在90%以上。     

Determination and interpretation of fractal properties of the sandstone pore system

A knowledge of fractal properties of the pore system is extremely useful with regard to the interrelationships between moisture transport and pore structure. The fractal dimension characterises the egree of resolutiondependence of a property. Given a completely interlaced pore system such as that of sandstone, the fractal dimension of the pore volume, or the porosity, quantifies the cross-sectional variability of the pore channels and is thus of great relevance with regard to transport processes. The fractal dimension of the pore surface describes the surface roughness. A newly-developed measuing technique is presented for the simultaneous determination of fractal dimensions of porosity and pore surface and for establishing fraction radii distributions in order to derive relevant parameters for moisture transport.     

Key to analyte migration and retention in electrochromatography

This work identifies electrical field-induced concentration polarization (CP) as a key physical mechanism influencing the retention behavior of charged analytes in electrochromatography with fixed beds of porous adsorbent particles. Due to an insufficient screening of intraparticle surface charge, under most general conditions the porous (permeable) particles become charge-selective. CP is caused by coupled mass and charge transport normal to the charge-selective external surface of the permeable particles, which leads to concentration gradients of ionic species in the adjoining interparticle electrolyte solution. Cation-exchange (cation-selective) particles were employed to investigate the influence of applied voltage on the retention factor of counterionic, i.e., positively charged, analytes. It is demonstrated by macroscopic retention data and microscopic studies resolving the CP phenomenon on a particle scale that the dependence of CP on electrical field and mobile-phase ionic strengths is directly reflected in concomitant changes of analyte retention. The CP zones that develop at the interface between interparticle and intraparticle pore space are recognized by charged, but not electroneutral analytes while entering or leaving the particles. The intensity of these convective-diffusion boundary layers (CP zones) depends on the applied field strength and charge selectivity of a particle. Thus, it is the charge-selective transport between the interparticle and intraparticle pore space in packed beds that prevails under typical experimental conditions in electrochromatography and that forms the physical basis for a general electrical field dependence of the retention factor of charged analytes.     

The fractal analysis of a porous material structure

The structure of porous copper and iron materials with a porosity ranging from 5 to 45% was studied by fractal analysis. A relationship between the fractal dimension of the porous space boundary and the porosity value is established. A correlation between topological features of the porous material structure and the fractal dimension of the interface is revealed.     

Three-dimensional fractal analysis of fracture surfaces in titanium–iron particulate reinforced hydroxyapatite composites: relationship between fracture toughness and fractal dimension

Fractal dimension has been considered as a measure of fracture surface roughness of materials. Three-dimensional (3D) surface analysis is anticipated to provide a better evaluation of fracture surface toughness and fractal dimension. The objective of this study was to quantify the fracture surfaces and identify a potential relationship between fracture toughness and fractal dimension in a new type of core–shell titanium–iron particulate reinforced hydroxyapatite matrix composites using SEM stereoscopy coupled with a 3D surface analysis. The obtained results showed that both fracture surface roughness and fractal dimension increased with increasing amount of core–shell Ti–Fe reinforcing particles. The fractal dimension was observed to be a direct measure of fracture surface roughness. The fracture toughness of the composites increased linearly with the square root of fractal dimensional increment (i.e., followed the Mecholsky–Mackin equation well) due to the presence of Ti–Fe particles along with the effect of porosity in brittle materials. The 3D fractal analysis was suggested to be a proper tool for quantifying the fracture surfaces and linking the microstructural parameter to fracture toughness.