Measuring and testing – With fluid pressure – Porosity or permeability
Reexamination Certificate
1999-07-02
2001-10-09
Larkin, Daniel S. (Department: 2856)
Measuring and testing
With fluid pressure
Porosity or permeability
Reexamination Certificate
active
06298711
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention pertains generally, to devices for investigation of physicochemical properties of materials and articles, in particular to devices for investigation of the structure of porous bodies.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98
Devices for investigation of the porous structure of samples are known.
Generally, they employ a method of nonwettable liquid intrusion into pores of a test sample namely mercury, and are known as mercury porosimeters (H. L. Ritter, L. C. Drake, Ind. Eng. Chem. Analit. Ed., 17, 787, 1945; SU Inventors Certificate No. 104315, 1952 G 01 (15/08).
The mercury porosimeters, which are the most widespread porosimetric devices, measure distribution of pores by the samples' radii within the pore size range from 2 to 10
5
nm.
However, measurements accomplished within the pore-size range from 2 to 7 nm require applying very high pressure to intrude mercury into the samples pores which is up to 4000 ATM and which involves a complicated device.
Under pressures of thousands ATM, deformation and destruction of most samples measured, especially plastic ones, takes place.
Besides, it is impossible to use mercury porosimeters for investigation of substances, which chemically react with mercury (amalgamation).
Also, when mercury porosimeters are used, the value of angle of wetting by mercury for most of the samples measured is not known. However, this value is used for computation of radii of pores measured.
In practice, various materials are measured when some mean value of this angle of wetting issued which entails significant errors in measurement.
Of great importance when employing mercury porosimeters is that it uses a substantial quantity of a highly toxic substance-mercury.
Also known in the art are devices for measurement of the porous structure of a substance by means of a method of capillary condensation, for instance an adsorption apparatus (A. W. Adamson, Physical Chemistry of Surface, John Wiley & Sons Publ., New York, 1976).
However, devices operating by the capillary condensation method provide sufficient accurate measurement of distribution of pores by radii only within the range from 1 (or -2) to 50 nm.
Also known is a device for measurement of characteristics of porous bodies by the method of standard porosimetry (USSR Inventor's Certificate No. 543852, 1975, GO1N15/08, Yu. M. Volfkovich, V. S. Bagotzky, J. Power Sources, 48 (1994) 327, 339).
The method is based on the fact that when pores of the test sample are filled with a wetting liquid or are free of the liquid, and when a determination of a quantity of liquid contained in its pores takes place, the test sample is brought into contact with the standard porous sample and when capillary equilibrium is achieved a measurement is performed of the quantity of the liquid in the test and standard samples.
The method consists in measurement, performed in the course of drying, of equilibrium dependency of a quantity of liquid in the test sample from its quantity in the standard sample while the samples are in contact with each other.
Proceeding from a curve plotted against results of measurements also from a known curve of distribution of pores by radii (porosimetric curve) for standard samples, it is determined under a specific procedure, porosimetric curves for the test samples.
By means of a mathematical processing of these curves other characteristics of a porous structure are obtained, for instance a specific surface.
A quantity of liquid in each porous sample is determined by means of weighing in the course of drying.
A device for measurement of the standard porosimetery consists of scales and a clamping device, wherein the test and standard porous samples are brought into contact.
The clamping device represents a body arranged as a beaker where the porous test and standard samples are placed. The samples are shut down by means of a draw plate having apertures through which drying of a stack is performed. A throw nut screwed on the body of the device clamps the samples to each other. To get one point on the porosimetric curve the stack is disassembled, the porous samples from the stack are laid out into individual bottles, and then after weighting, all samples are removed from the bottles, and the stack is reassembled anew in the clamping device. Then the next portion of the liquid is evaporated from the stack through drying, by means of a flow of dry gas or by vacuum, after which the stack of the porous bodies is disassembled, the porous bodies are laid out anew into the individual bottles, and then are weighed again.
To measure one porosimetric curve it is necessary depending on the required accuracy of measurement, to conduct this cycle of operations from fifteen up to fifty times. All of these stages are labor intensive and require a prolonged measurement process.
All the above known in the art decisions do not provide for a quickly obtaining accurate measurement results, and are not used for all ranges of pore radii. The process of measurement is a prolonged and laborious one.
BRIEF SUMMARY OF THE INVENTION
It is the primary object of the present invention to provide a porosimeter—a device for investigation of physicochemical properties of materials and articles, in particular for investigation of the structure of porous bodies.
It is another object of this invention to provide a porosimeter for investigation of the structure of porous bodies which permits in a fast manner and in an automatic operating mode to perform measurements within the maximum broad ranges of radii of pores for test samples of any chemical nature and strength.
Yet another object of the invention is to provide a porosimeter for investigation of the structure of porous bodies, which enables to increase the accuracy of measurements.
It is still another object of this invention to provide a porosimeter for investigation of the structure of porous bodies to define a greater quantity of information, including a specific surface, statistic characteristics of form and size of pores, marginal angles of wetting, characteristics of swelling, characteristics of a structure of multi-component hydrophobic-hydrophilous porous bodies and other characteristics.
According to these and other objects, the porosimeter of the present invention, having a scale and a clamping device for bringing the standard and test porous samples into tight contact with each other, said samples containing a wetting liquid in their pores, comprises an automatic manipulator consisting of a body, a frame and a motor connected through a transmission with the frame, said frame being provided with pushers and a support, while the device for bringing into tight contact of the standard and test porous samples additionally comprises a drying device which is connected with the body, and yokes having apertures to provide contact between the porous samples, said yokes being arranged as having catchers.
The drying device is preferred to be a cylindrical chamber with a bottom containing apertures, while a beaker having an outlet pipe is coaxially fixed inside of the chamber, said beaker being disposed by its open end towards the chamber's bottom, and having a clearance between an external surface of the beaker and an internal cylindrical surface of the chamber.
It is preferred that the yokes be cylindrical beakers entering each other and be provided with spring shock absorbers, spring washers and a ring-shaped slot arranged in the bottom of a yoke.
It is expedient that in the porosimeter for investigation of physicochemical properties of the materials and articles catchers are resilient and constituting balls which are spring-loaded by resilient plates, said balls possessing different pressing force to press tight the yokes to each other and to the drying chamber the less rather than the greater diameter of the yoke, while the balls are to be accomplished as possessing ability to enter respective grooves arranged in the yokes and in the dryin
Blinov Igor Alexandrovich
Kulbachevsky Venedikt Venedictovich
Sosenkin Valentin Evseevich
Volfkovich Yury Mironovich
Jacobson & Holman PLLC
Larkin Daniel S.
Porotech, Inc.
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