压汞仪原理课件.pptx

1、压汞仪原理压汞仪原理Analysis Basic Theoryq 浸润/非浸润Wetting/Non-wettingq 接触角Contact Angleq Washburn 方程q 压力生成Pressure Generationq 体积的电容测量Capacitance measurement of volume基本原理基本原理The Fundamental Principle非浸润在颗粒之间的液态汞被压入孔中,被汞侵入的孔径是所用压力的函数.这个特性被用来表征广泛的微粒和固体材料.The forced intrusion of liquid mercury between particles

2、and into pores as a function of applied pressure is routinely employed to characterize a wide range of particulate and solid materials.浸润/接触角Wetting/Contact Angles浸润 90Contact Angle:Hg on a variety of materials毛细管现象Capillarity毛细上升Capillary rise 90Washburn 方程and Where P is in MPa and r in m压汞法Mercury

3、 Intrusionq在颗粒之间的液态汞被压入孔中,被汞侵入的孔径是所用压力的函数.这个特性被用来表征广泛的微粒和固体材料.The forced intrusion of liquid mercury between particles and into pores is routinely employed to characterize a wide range of particulate and solid materials.q绝大多数材料都能满足仪器对样品直径的分析要求,即样品直径应限制在2.5cm 以内(对于GT共同，为10mm以内).Most materials can be

4、analyzed so long as the sample can be accommodated in the instrument,which typically restricts the sample dimensions to no more than 2.5cm(GT:10mm).我们从压汞法中能了解什么?What Can We Learn From Mercury Intrusion?q 孔体积Pore volumeq 孔径分布Pore size distributionq 孔面积Pore Areaq 孔结构Pore structureq 粒度分布Particle size d

5、istributionq 孔体积测定范围孔体积测定范围最主要依赖于仪器的压力范围最主要依赖于仪器的压力范围,但但也依赖于接触角也依赖于接触角.Pore size range depends predominantly on the instrument pressure range but also on the contact angle.q 孔径上限孔径上限受可得到的最低填充压力限制受可得到的最低填充压力限制,而而孔径下孔径下限限则受最高填充压力限制则受最高填充压力限制.The largest pore size is limited by the lowest filling press

6、ure attainable and the smallest pore size by the highest.q 可测定粉末样品的粒度分布.The particle size distribution of powders can be determined.应用大孔样品的孔径分布图 q在压制和烧结过程的研究中压汞法是极其有用的分析工具.Mercury intrusion is an extremely useful analytical tool in the investigation of both compaction and sintering processes.q 在一次测量

7、中，能分析光纤、含纤维材料、织物及在一次测量中，能分析光纤、含纤维材料、织物及过滤介质的孔直径、渗透性和孔曲率过滤介质的孔直径、渗透性和孔曲率.Fibers,fibrous mats,fabrics and filter media in general can be analyzed for pore size,fiber diameter,permeability and tortuosity in a single measurement.q与汞能形成汞齐的材料不能用压汞法分析。Those materials that amalgamate with mercury cannot be

8、analyzed.应用压汞实验的必要条件Experimental Requirements q 样品管(膨胀计)Cell(penetrometer)to hold the test sample.q 真空/填充装置,用于从样品管和样品的孔中去除空气并将汞转移进样品管.Vacuum filling apparatus to remove air from the cell and pores within the sample and for transferring mercury into the sample cell.q 压力发生器.Pressure generatorq 能容纳样品管的

9、高压仓(高压腔).High-pressure vessel to contain the sample cell.q 测量电路:监测汞体积的改变,它是所用压力值的函数Measuring circuits to monitor change in mercury volume as a function of applied pressure.q 液压油:传导发生器产生的压力至样品管.Hydraulic fluid to transmit the pressure from the generator to the sample cell.样品管Sample Cell样品管或膨胀计:用来装样品,

10、并便于注汞/排汞体积的测量.The sample cell or penetrometer(sometimes called a dilatometer)is used both to contain the sample and to facilitate the measurement of intrusion and extrusion volumes.样品管Sample Cell样品管或膨胀计:通过金属外套和电极帽(平板电极)进行注汞/排汞体积的测量.The sample cell or penetrometer is used both to contain the sample a

11、nd to facilitate the measurement of intrusion and extrusion volumes via metal sheath and electrode cap.CONVENIENCE:Penetrometers(sample cells):one style accommodates both powders and bulk solids for reduced penetrometer inventory requirements.Removable metal sheath allows easy viewing of penetromete

12、r stem to confirm proper fill and no powder elutriation(fluidization).Macrocell option for core cylinders up to 2.5 cm diameter and 3.5 cm long.FIGURE:POREMASTER SHORT SAMPLE CELL ASSEMBLY FOR LOW PRESSURE MEASUREMENTS Short sample cell(P/N 74012)2 mm ID(P/N 74014)4 mm IDUpper Cell Housing(short cel

13、l)(P/N 04000-6405)O-ring(P/N 51001-112)Cell contact assemblyP/N 01559压力压力Pressure 注汞注汞Intrusion实验综述Experimental Overviewq电容法测量体积Volume measurement capacitance techniqueq接触角Contact angle(130-140)q样品管抽真空Sample cell evacuation(prevent elutriation)q汞填充Fill with mercuryq低压注汞/排汞Low pressure intrusion/extr

14、usionq转移至液压系统,排除空气Transfer to hydraulic system,air purgeq高压注汞/排汞(扫描或步进方式)High pressure intrusion/extrusion(scan or step)实验结果综述Results Overview压力值pressure体积变化Volume change滞留entrapment可逆压缩(无迟滞或滞留)Reversible compression(no hysteresis or entrapment)内部孔的迟滞Hysteresis from internal pores颗粒间的空隙可能排出其中的汞,也可能不

15、依赖于粉末压紧后的刚性Interparticle voids may give up their mercury or not depending on the rigidity of the powder“compact”颗粒重排 Particle rearrangement(大孔/空间large pores/spaces)(小孔/空间small pores/spaces)曲线的总体观察曲线的总体观察 General ObservationsSee graphical representation next举例:三段式注汞曲线Example:3 Stages of Mercury“Intru

16、sion”粉末压缩Powder Compression空体积填充Void Filling孔填充Pore Filling表观孔直径Apparent pore diameter(log scale)volume(Large)(Small)曲线的总体观察曲线的总体观察 General Observationsq 大孔在低压填充,小孔在高压填充 Large pores fill at low pressures,smaller pores at higher pressures.q 颗粒间的空隙也在低压填充并能干扰数据判读Interparticle voids also fill at lower p

17、ressures and can interfere with the interpretation of data.q 松散的粉末在增压的影响下能被压紧 Loose powders may compact under the influence of the increasing pressure.logPApparent Volume Intruded实验结果综述Results Overview迟滞现象迟滞现象Hysteresis注汞曲线不能顺原路返回(排汞曲线位于注汞曲线上方)Intrusion curves are not retraceable(Extrusion curves li

18、e above the intrusion curve)注汞和排汞之间的的改变能解释迟滞现象 Can be explained by changes in between intrusion and extrusion一些汞会残留在孔中.Some mercury remains in the pores滞留现象滞留现象Entrapment 滞留现象滞留现象:汞遗留在孔中汞遗留在孔中.Mercury left behind in the pores:entrapment 在第一次循环之后在第一次循环之后,滞留现象滞留现象终止终止.Entrapment ceases after the first

19、 few cycles 具有复杂网状结构的孔会产生这样的滞留 Complex network of pores responsible for such entrapmentq 样品室Sample compartmentq 样品管管颈大小Stem sizeq 巨型管Macro cellq 粉末样品Powders 样品准备:选择和装填样品管Sample Preparation:Selecting and Loading Sample Cell q 慢抽(细抽)真空Fine evacuationq 时间,压力Time,pressureq快抽(粗抽)真空Coarse evacuationq时间,压力

20、Time,pressure样品准备:抽真空参数Sample Preparation:Evacuation ParametersAnalysis Low Pressureq Rangeq Intrusion/Extrusionq Fill pressureq RepeatsAnalysis Densityq WeighingsAnalysis High Pressureq Transfer of sample cellq Rangeq Intrusion/Extrusionq Scanning/Stepwiseq Repeats报告(数据处理)Reports(Data Reduction)q 文

21、件综合File Integrationq 减除空白Blank Subtractionq 单位Unitsq 孔径分布Pore Size Distributionsq 其它计算Other Calculationsq 进一步解释Further Interpretation 报告(数据处理)Reports(Data Reduction)文件综合File Integrationq 合并低压和高压文件 Merging Low Pressure&High Pressure Files q 合并后可观察到迟滞程度 What Happens to Hysteresis?报告(数据处理)Reports(Data

22、Reduction)减除空白Blank Subtractionq 空管Empty cell偏离零点的原因:Deviations from zero:受热Heating遇冷Cooling可压缩性Compressibility电介质改变Dielectric change其它Other报告(数据处理)Reports(Data Reduction)单位Unitsq 压力Pressureq 尺寸Size q 半径/直径Radius/Diameter报告(数据处理)Reports(Data Reduction)孔径分布Pore Size Distributionsq 累积量(积分)Cumulativeq

23、dV/dr(微分)q dV/dlogr(对半径对数的微分)q 直方图(柱状图)Histograms q 内插法Interpolation报告(数据处理)Reports(Data Reduction)进一步阐述Further Interpretationsq 汞滞留Entrapmentq 接触角迟滞Contact angle hysteresisq 压实/扭曲Compaction/bucklingq 压碎强度分布Crush strength distribution 压实CompactionCalculations表面积计算表面积计算Surface Area Calculation表面积计算表面

24、积计算(续续)Surface Area(continued)表面积表面积Surface Areabetween 34.5(r=0.0213 m)and 414 MPa (r=0.00178 m)图1是一条累积孔体积曲线，该曲线显示出进入孔道的总体积以及颗粒间的空隙对施加的压力的曲线。利用公式积分计算可得所有孔道以及注汞压力P下的孔隙的表面积.曲线上最开始的斜率很陡，是因为汞压入了大孔和颗粒间的空隙。在接近于5000psia以上出现变化意味着汞开始注入半径为0.02 m的孔内，而且随着压力升高，汞逐渐压入更窄的孔道内。在大于30,000 psia未呈现明显的压入，则表明孔径小于0.0035 m的

25、孔极少。压力(psia)10000 20000 30000 40000 50000 60000孔径/面积分布Pore Size/Area Distribution是体积孔径分布(孔体积/单位孔半径)is the volume pore size distribution(pore volume/unit pore radius)是孔面积分布(孔面积/单位孔半径)is the pore surface area distribution(surface area/unit pore radius)孔径/体积/面积分布图 Pore Size/Volume/Area Distributionarea

26、volume报告(数据处理)Reports(Data Reduction)其它计算Other Calculationsq 密度Densityq 孔隙率Porosity-材料中孔隙的总体积与整个材料的体积之间的比率q 颗粒粒径Particle Sizeq 孔喉比Throat/Pore Ratioq 压缩率Compressibility-可压缩的程度q 渗透率Permeability-液体或气体通过多孔材料的流速q 孔曲率Tortuosity-弯曲的性质或状态q 分形维数Fractal Dimension孔隙率Porosity =porosityHg=mercury densityHe=heliu

27、m density颗粒的孔隙率 Particle Porosityq 颗粒间的孔隙率 Interparticle porosity 通过测量颗粒间的空体积This is a measure of the void volume between the particles.q 颗粒内的孔隙率 Intraparticle porosity通过测量颗粒间内被孔占据的体积This is a measure of the volume occupied by pores within the particles.颗粒的孔隙率(续)Particle Porosity(continued)需要松装体积(堆密

28、度)信息,这可以直接输入,也可以从汞置换重量中计算得到.Requires bulk volume(density)information which can be input directly or calculated from the weight of mercury displaced.Particle Size Theories q MS(Mayer-Stowe)Theoryq SS(Smith-Stermer)Theory粒径计算原理粒径计算原理Particle Size Theories粒径计算原理粒径计算原理Particle Size Theories(通常为10.73 for

29、=140 and a=37.5%)Mayer-Stowe Theory(MS)=穿透压力breakthrough pressure(N/m)=比例常数proportionality constant=颗粒直径 particle diameter(m)Smith-Stermer Theory(SS)是一个描述在固定直径D 的颗粒之间注汞的核心文件.is a kernel that describes mercury intrusion between particles of fixed diameter D.是粒径分布is the particle size distributionParti

30、cle Size DistributionsPore-Throat RatiosThroatPore孔曲率Pore TortuosityDeff=有效扩散系数effective diffusivity Db=自由(散装)流体的扩散系数bulk fluid diffusivity c=孔体积分数pore volume fraction =扭曲系数 tortuosity factor渗透率PermeabilityK=渗透率permeability =粉末床的孔隙率powder bed porositydp=平均孔直径average pore diameter分形维数Fractal Dimensio

31、n(D)和普通维数（0，1，2，3）相对应的维数称为分形维数。通常，它们的维数值不是整数。分形维数是表征表面粗糙度的参数 A parameter that characterizes the degree of roughness of a surface 最完美的平坦表面 D=2 A perfectly flat surface has D=2 最粗糙的表面 D=3 A completely rough surface has D=3 真实表面:2 D 3 Real surfaces have 2 D 3关于分形维数(D)历史 在欧氏空间中，人们习惯把空间看成三维的，习惯于整数的维数。分形理

32、论把维数视为分数。为了定量地描述客观事物的“非规则”程度，1919年，数学家从测度的角度引入了维数概念，将维数从整数扩大到分数，从而突破了一般拓扑集维数为整数的界限。关于分形维数(D)-概念 分维的概念:首先画一个线段、正方形和立方体，它们的边长都是1。将它们的边长二等分，此时，原图的线度缩小为原来的1/2，而将原图等分为若干个相似的图形。其线段、正方形、立方体分别被等分为21、22和23个相似的子图形，其中的指数1、2、3，正好等于与图形相应的经验维数。一般说来，如果某图形是由把原图缩小为1/a的相似的b个图形所组成，有：aD=b,D=logb/loga的关系成立，则指数D称为相似性维数，D

33、可以是整数，也可以是分数。关于分形维数(D)分形几何与传统几何相比有什么特点：分形几何与传统几何相比有什么特点：1.从整体上看，分形几何图形是处处不规则的。例如，海岸线和山川形状，从远距离观察，其形状是极不规则的。2.在不同尺度上，图形的规则性又是相同的。上述的海岸线和山川形状，从近距离观察，其局部形状又和整体形态相似，它们从整体到局部，都是自相似的。当然，也有一些分形几何图形，它们并不完全是自相似的。其中一些是用来描述一般随即现象的，还有一些是用来描述混沌和非线性系统的。为什么要研究分形？为什么要研究分形？q 分形形态是自然界普遍存在的，研究分形，是探讨自然界的复杂事物的客观规律及其内在联系

34、的需要，分形提供了新的概念和方法。q 分形具有广阔的应用前景，在分形的发展过程中，许多传统的科学难题，由于分形的引入而取得显著进展。q 分形作为一种新的概念和方法，正在许多领域开展应用探索。80年代初国外开始的“分形热”经久不息。q 美国著名物理学家惠勒说过：今后谁不熟悉分形，谁就不能被称为科学上的文化人。分形维数(D)-计算过程1.作图Plot:log(dv/dp)vs logP2.拟合直线,测定斜率S Fit straight line;determine slope,S3.分形维数Fractal Dimension,D=4+S4.(斜率是负值 slope is negative)Frac

35、tal Dimension(D)Fractal Dimension(D)D=2.9取压力值220的数据Log(P)Fractal Dimension(D)D=2.03取压力值10005000的数据Log(P)需注意的问题More Resultsq 粉末在低压下可能重排,即它们被压成一体或被压缩.Powders may rearrange at low pressures,i.e.they compact or compress.q一些非常软的低密度材料,如硅胶会有类似压弯曲的过程.Some very weak low density materials,such as silica gels,

36、may also undergo a similar process of”buckling”.q如果样品弹性是可逆的,固体压缩与迟滞现象不是通常的相关.Solid compression,which if elastic is reversible,is not normally associated with significant hysteresis.需注意的问题(续)More Resultsq 对于海绵材料,在汞有机会进入其中之前,它能通过孔的收缩被压缩.当汞侵入后,汞能够改变孔结构并导致报告的孔径小于实验开始时存在的孔径.Spongy materials may compress

37、by shrinkage of the pores before mercury has an opportunity to intrude into them.When the mercury does intrude,it is into an altered pore structure and may report sizes smaller than exist in the starting material.压缩率压缩率(海绵材料海绵材料)Compressibility(Spongy material)2500050001000015000200001.00.80.60.40.2

38、0Pressure,psiReversible compression压缩率压缩率Compressibility一些实际经验Some Practical Observationsq最大的可能压力约为400MPa(60,000 psi or 4,000 个大气压),汞不能进入孔直径3.6nm以下的孔.所以,该技术不能用于评估微孔(2nm以下的孔).At the maximum possible pressure,approximately 400MPa(60,000 psi or 4,000 atmospheres),mercury is able to penetrate into pores

39、 no smaller than 3.6nm(36 angstroms).Therefore,this technique cannot be used to evaluate micropores(less than 2nm diameter by IUPAC definition).滞留现象滞留现象Entrapmentq 不是所有被压入的汞在减压过程中都能被排出.当外部压力降低时,少量汞无力从孔网中流出而残留或深陷在样品中.Not all intruded mercury is extruded from the sample during depressurization.Retaine

40、d,or entrapped mercury results from the inability of mercury to flow back out of a pore network sufficiently quickly when the external pressure is dropped.q 一般来说,降压越快,残流的汞越多.这是由于在孔网中汞流的有限的抗张强度所致.Typically,the faster the depressurization the greater the quantity of entrapped mercury.This is due to th

41、e limited tensile strength of the thread of mercury running through the pore network.Standard Methods ASTMq D4404-84(1998)e1 Standard Test Method for Determination of Pore Volume and Pore Volume Distribution of Soil and Rock by Mercury Intrusion Porosimetryq D4284-92 Standard Test Method for Determi

42、ning Pore Volume Distribution of Catalysts by Mercury Intrusion Porosimetryq D2873-94(1999)e1 Standard Test Method for Interior Porosity of Poly(Vinyl Chloride)(PVC)Resins by Mercury Intrusion PorosimetryStandard Methods BSiq BS 7591-1:1992 Porosity and pore size distribution of materials.Method of evaluation by mercury porosimetry.USPq USP精品课件精品课件！精品课件精品课件！