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AutoPore IV 2017

Micromeritics' AutoPore IV 9500 Series characterizes a material’s porosity by applying various levels of pressure to a sample immersed in mercury. The pressure required to intrude mercury into the sample’s pores is inversely proportional to the size of the pores. This is called mercury porosimetry, or often, “mercury intrusion.”

The AutoPore IV series provides high-quality analysis data and comes with enhanced data reduction and reporting packages, faster pressure ramp rates, a more flexible and controllable vacuum system, and a redesign of both the low-and high-pressure generation systems.

AutoPore IV Features:

The term "porosimetry" is often used to include the measurements of pore size, volume, distribution, density, and other porosity-related characteristics of a material. Porosity is especially important in understanding the formation, structure, and potential use of many substances. The porosity of a material affects its physical properties and, subsequently, its behavior in its surrounding environment. The adsorption and permeability, strength, density, and other factors influenced by a substance’s porosity determine the manner and fashion in which it can be appropriately used.

The mercury porosimetry analysis technique is based on the intrusion of mercury into a porous structure under stringently controlled pressures. Besides offering speed, accuracy, and a wide measurement range, mercury porosimetry permits you to calculate numerous sample properties such as pore size distributions, total pore volume, total pore surface area, median pore diameter, and sample densities (bulk and skeletal).

The AutoPore IV Series Mercury Porosimeters can determine a broader pore size distribution (0.003 to 1100 micrometers*) more quickly and accurately than other methods. These instruments are enhanced with features that enable them to more accurately gather the data needed to characterize the porous structure of solid materials. They also offer new data reduction and reporting choices that provide more information about pore geometry and the fluid transport characteristics of the material.

*Calculated with an initial filling pressure of 0.2psia (0.00128MPa)

Wide Variety of Benefits:

  • Controlled pressure can increase in increments as fine as 0.05 psia from 0.2 to 50 psia. This allows detailed data to be collected in the macropore region.
  • A quick-scan mode allows a continuous pressure increase approximating equilibrium and providing faster screening. The high repeatability and reproducibility of this method by the AutoPore means that small, but significant, differences between samples will be detected. You can use this technique to screen a sample for conformity to specification because repeatability remains high.
  • High-resolution (sub-microliter) measurement of intrusion/extrusion volumes produces extraordinary precision allowing the development of tighter sample specifications, improved production processes, and high-quality research data.
  • A choice of correction routine for baseline (automatic, differential, or manual) produces greater accuracy by correcting for compressibility and thermal effects caused by high pressure.
  • Choice of pressure ramping methods lets you choose the scanning technique for high-speed or on-demand results, or equilibration techniques for more accurate results with greater detail.
  • The instrument allows the user to program data collection using a minimum number of data points. However, during intervals of unexpectedly large amounts of intrusion, the AutoPore will automatically collect additional data points.
  • Choose between three data plot routines constructed of collected data points, a continuous curve plotted from interpolated data, or a combination of points and curves.
  • A variety of pore volume, pore area, and pore size plots is available as well as the ability to calculate total intrusion volume, total pore (surface) area, median pore diameter, average pore diameter, bulk density, and apparent (skeletal) density.

  • Capability to measure pore diameters from 0.003 to ~1100 µm*
  • Low noise, high-pressure generating system
  • Enhanced data reduction package; includes tortuosity, permeability, compressibility, pore-throat ratio, fractal dimension, Mayer-Stowe particle size, and more
  • Operates in scanning and time – or rate – equilibrated modes
  • Collects extremely high-resolution data; better than 0.1 µL for mercury intrusion and extrusion volumes
  • Controlled evacuation prevents powder fluctuation

Operating Software:

The AutoPore offers various options for obtaining important sample information as quickly as possible and for presenting the data in a format which you can design. Analysis options include choice of analysis variables, equilibration techniques, and pressure points at which data are collected. After operating conditions for the instrument have been chosen, they can be stored as a template and then reapplied to other samples, saving time and reducing the potential for human error.

A selection of report options lets you customize many aspects of the data pages. You can select a specific range of data to be used in calculations; arrange columns of tabular data; select cumulative, incremental, or differential plots; scale the X-axis to display in either logarithmic or linear format for pore size; report actual or interpolated data; and select data presentation units such as psia or MPa, diameter or radius, and micrometers or Angstroms.

Data Reduction:

The AutoPore IV generates tabular and graphical reports of percentage pore volume vs. diameter, and a summary report of percentage porosity in user-defined size ranges. The user has the ability to average several analyses and to use the ‘resulting average’ analysis as a reference with which to compare subsequent analyses. A standard, single, user-defined analysis may also be entered and used for subsequent comparisons. SPC reports are available with collected data or user-defined parameters. In addition to the standard data reduction methods, the AutoPore IV Series also provides the following:

  • Mayer-Stowe Particle Size - Reports equivalent spherical size distributions
  • Pore Tortuosity - Characterizes the efficiency of the diffusion of fluids through a porous material
  • Material Compressibility - Quantifies the collapse or compression of the sample material
  • Pore Number Fraction - Reports the number of pores in different size classes
  • Pore-throat Ratio - Reports the ratio of pore cavities to pore throats at each percent porosity filled value
  • Pore Fractal Dimensions - Quantifies the fractal geometry of a material
  • Permeability - Reports the ability of the sample to transmit fluid

Porosimetry Defined:

The term "porosimetry" is often used to include the measurements of pore size, volume, distribution, density, and other porosity-related characteristics of a material. Porosity is especially important in understanding the formation, structure, and potential use of many substances. The porosity of a material affects its physical properties and, subsequently, its behavior in its surrounding environment. The adsorption, permeability, strength, density, and other factors influenced by a substances porosity determine the manner and fashion in which it can be appropriately used.

Analysis Defined:

Since mercury does not wet most substances and will not spontaneously penetrate pores by capillary action, it must be forced into the pores by the application of external pressure. The required equilibrated pressure is inversely proportional to the size of the pores, only slight pressure being required to intrude mercury into large macropores, whereas much greater pressures are required to force mercury into small pores. Mercury porosimetry analysis is the progressive intrusion of mercury into a porous structure under stringently controlled pressures. From the pressure versus intrusion data, the instrument generates volume and size distributions using the Washburn equation. Clearly, the more accurate the pressure measurements, the more accurate the resulting pore size data.

The penetrometer consists of a sample cup bonded to a metal-clad, precision-bore, glass capillary stem. The sample is placed in the sample cup; during analysis, mercury fills the cup and capillary stem. As pressure on the filled penetrometer increases, mercury intrudes into the sample’s pores, beginning with those pores of largest diameter. The mercury moves from the capillary stem resulting in a capacitance change between the mercury column inside the stem and the metal cladding on the outer surface of the stem. The AutoPore detects very slight changes in capacitance (equivalent to a difference of less than 0.1 microliter of mercury) so extraordinary resolution is achieved.

Micromeritics also offers a large selection of penetrometer bulbs, volumes, stems, and closures designed to fit most sample forms, shapes, porosity, and quantity. The better the match between the sample, its porosity, and the measurement range of the sample cell, the more precise the results.

Ceramic Industry Magazine, on-line article:

"Mercury Intrusion Porosimetry"

Click here for Mercury Intrusion Porosimetry Theory Poster

Pharmaceuticals: Porosity and surface area play major roles in the purification, processing, blending, tableting, and packaging of pharmaceutical products as well as a drug’s useful shelf life, its dissolution rate, and bio-availability.

Ceramics: Pore area and porosity affect the curing and bonding of greenware and influence strength, texture, appearance, and density of finished goods.

Adsorbents: Knowledge of pore area, total pore volume, and pore size distribution is important for quality control of industrial adsorbents and in the development of separation processes. Porosity and surface area characteristics determine the selectivity of an adsorbent.

Catalyst: The active surface area and pore structure of catalysts influence production rates. Limiting the pore size allows only molecules of desired sizes to enter and exit, creating a selective catalyst that will produce primarily the desired product.

Aerospace: Surface area and porosity of heat shields and insulating materials affect weight and function.

Fuel Cells: Fuel cell electrodes require controlled porosity with high surface area to produce adequate power density.

Geoscience: Porosity is important in groundwater hydrology and petroleum exploration because it relates to the quantity of fluid that a structure can contain as well as how much effort will be required to extract it.

Filtration: Pore size, pore volume, pore shape, and pore tortuosity are of interest to filter manufacturers. Often, pore shape has a more direct effect upon filtration than pore size because it strongly correlates with filtration performance and fouling.

Construction Materials: Diffusion, permeability, and capillary flow play important roles in the degradation processes in concrete, cement, and other construction materials.

Paper: The porosity of print media coating is important in offset printing where it affects blistering, ink receptivity, and ink holdout.

Medical Implants: Surface area and porosity of heat shields and insulating materials affect weight and function.

Confirmation of performance is desirable from time to time for every analytical instrument. The need for validation can arise from a change of operators, a peculiar result, an unfamiliar material, or simply from equipment wear and tear. Micromeritics products, with a few exceptions, do not require calibration per se; they derive results from well-established laws utilizing detection of basic parameters such as time, temperature, pressure, mass, and the like. Micromeritics instruments, nevertheless, are no exception to the desirability for periodic performance evaluation, because detectors, like everything else, age, drift, and occasionally fail.

An effective means for detecting operational mistakes or erroneous applications and for assuring consistent, reproducible results is to retain a quantity of one or more appropriate materials with known, well-characterized properties which can be used to test instrument performance. The reference materials subsequently listed by primary property are offered by Micromeritics for this corroborative purpose. Each has been carefully selected to be representative of the parameter, or parameters, for which it is recommended, to be non-hazardous, and to have an extended shelf life.

The lot of material from which each reference portion was extracted has been repeatedly analyzed. This has been done on a number of instruments, by different operators, and, in some cases, even using different techniques. We do not claim our reference materials to be standards. The extensive, blind testing utilizing independent laboratories which would enable us to make such a statement has not been undertaken. We are confident, nevertheless, and so assert, that an instrument giving the result, or results, within the limits specified with each reference material is operating satisfactorily.

When you order a reference material, you will receive information on how best to prepare it for analysis, the recommended quantity for a test, and other essential data. Material properties are tabulated along with their limits of accuracy. As appropriate, a typical property trace such as a size distribution or an intrusion and extrusion curve is included.