CN209894637U

CN209894637U - Device for testing true density of material based on physical adsorption instrument

Info

Publication number: CN209894637U
Application number: CN201822256323.3U
Authority: CN
Inventors: 丁延伟; 刘吕丹; 白玉霞
Original assignee: University of Science and Technology of China USTC
Current assignee: University of Science and Technology of China USTC
Priority date: 2018-12-29
Filing date: 2018-12-29
Publication date: 2020-01-03
Anticipated expiration: 2028-12-29

Abstract

The utility model discloses a device based on physical adsorption appearance test material true density, including adsorption appearance vacuum system (1), manifold system (2), manifold system connecting valve (3), sample cell connector (4), sample cell (5), dewar bottle lid (6), filling rod (7), liquid nitrogen (8), sample (9), sample cell sample room (10), P0 pipe (11) and dewar bottle (12), sample cell (5) that are equipped with filling rod (7) and sample (9) are connected with vacuum system (1) of adsorption appearance through sample cell connector (4), cover dewar bottle lid (6), sample cell sample room (10) for bottom confined cylindrical structure, can hold more samples. The utility model discloses need not through the true density appearance of commercialization, can the direct measurement obtain the true density information of material.

Description

Device for testing true density of material based on physical adsorption instrument

Technical Field

The utility model relates to a technical field of physical adsorption test, in particular to device based on physical adsorption appearance test material true density.

Background

True density refers to the actual volume of solid material within the volume of the material in an absolutely dense state, excluding internal pores or interparticle voids (called true density). The prior national standard and the industry standard in China are as follows: GB/T533, GB/T1033.1, GB/T6155, GB/T23561, YB/T5300, JB/T7984.3, GB/T1713, GB/T8929, GB/T1713, GB/T208, GB/T5071, QB/T1010, GB/T9966, GB/T18856, GB/T24203, GB/T8330, SL-237 and other standards all adopt a density bottle (pycnometer) method to measure the true density of the material. In this way, the finer the material is ground, the more precise the value of the compact volume that can be measured in the pores of the material. The use of the densitometer method to test the true density of a material presents several problems that affect the test results, such as: (1) the adopted wetting liquid may dissolve and react with the sample during the test; (2) if the immersion liquid is not properly selected, the situation that the surface is not easy to be immersed can be generated, and the test result is influenced; (3) in testing powdered materials, when the powder is fully immersed in a liquid, its bubbles must be completely excluded to determine the volume it excludes. The method of measuring true density by the densitometer method is cumbersome in operation and does not necessarily ensure complete removal of bubbles. The current commercial instruments commonly use "gas displacement" to measure the true density of a material. The instrument adopts helium to replace the impregnating solution, and the helium is micromolecular inert gas and has the advantages of easy diffusion, good permeability and good stability, helium molecules can quickly penetrate into the inner pores of the material during measurement, the pores, irregular surface depressions and the like of the material, which cannot be measured by the conventional method, can be quickly filled, and the measured sample volume is closer to the real volume of the sample than that of a density bottle method, so that the real density value of the sample is closer to the real value. The utility model discloses the physical adsorption appearance of the volume law principle of commercialization based on information such as the specific surface area, aperture distribution and the hole volume that are used for measuring the material usually measures the sample cell that obtains and vacuum manifold's free space's data in carrying out the physical adsorption process, has developed a measuring method that can be used for measuring the true density of material.

SUMMERY OF THE UTILITY MODEL

The utility model discloses mainly solve following technical problem: a device for testing the true density of a material based on a physical adsorption instrument is developed according to free space data of a sample tube and a vacuum manifold measured by the physical adsorption instrument based on a commercialized volumetric method principle in the physical adsorption process.

The utility model discloses a technical scheme do: the utility model provides a device based on physical adsorption appearance test material true density, including adsorption appearance vacuum system, the manifold system, manifold system connecting valve, the sample cell connector, the sample cell, the dewar bottle lid, the filler rod, liquid nitrogen, the sample cell, P0 pipe and dewar, include manifold system and manifold system connecting valve in the adsorption appearance vacuum system, manifold system connecting valve and sample cell connector, the dewar bottle lid is the lid of dewar bottle, be equipped with liquid nitrogen in the dewar bottle, adsorption appearance vacuum system passes through P0 union coupling dewar bottle, the sample cell is connected with the sample cell, the sample cell that is equipped with filler rod and sample passes through the sample cell connector and is connected with the vacuum system of adsorption appearance, cover the dewar bottle lid, the sample cell be the cylindrical structure of bottom confined, can hold more samples.

Compared with the prior art, the utility model the advantage lie in:

the utility model discloses need not through the true density appearance of commercialization, can the direct measurement obtain the true density information of material.

Drawings

FIG. 1 is a schematic diagram of the operation principle of a physical adsorption apparatus based on the volumetric method principle; wherein, 1, a vacuum system of an adsorption instrument; 2-a manifold system; 3-manifold system connection valve; 4-sample tube connection port; 5-sample tube; 6-Dewar flask lid; 7-a filling rod; 8-liquid nitrogen; 9-sample; 10-sample cell; 11-P0 tube; 12-a dewar flask;

Detailed Description

The present invention will be further described with reference to the accompanying drawings and the detailed description.

As shown in fig. 1, a device for testing the true density of a material based on a physical adsorption apparatus comprises an adsorption apparatus vacuum system 1, a manifold system 2, a manifold system connection valve 3, a sample tube connection port 4, a sample tube 5, a dewar cover 6, a filling rod 7, liquid nitrogen 8, a sample 9, a sample tube sample chamber 10, a P0 tube 11 and a dewar 12, wherein the sample tube 5 filled with the filling rod 7 and the sample 9 is connected with the adsorption apparatus vacuum system 1 through the sample tube connection port 4, and the dewar cover 6 is covered. The sample cell sample chamber 10 is a cylindrical structure with a closed bottom end, and can accommodate more samples. A certain amount of helium is added to the sample tube at room temperature by opening and closing the valve 3 in the instrument vacuum system, and the pressure change before and after the addition of helium is measured by a pressure sensor to obtain the thermal free space volume. The dewar 12 filled with liquid nitrogen 8 is raised to the specified height by the mechanical system of the instrument, so that the sample chamber of the sample tube is completely immersed below the liquid nitrogen level. After the balance, a certain amount of helium is added into the sample tube through the opening and closing of the manifold system connecting valve 3, and the pressure change before and after the addition of the helium is measured through the pressure sensor to obtain the volume of the cold free space.

In the experiment, the volume obtained by measuring the change in pressure before and after filling the sample tube with helium at room temperature is called the volume of thermal free space (war space), and V is used_FWAnd (4) showing. Measured V_FWCan be expressed by the following equation (1):

in the above formula, the first and second carbon atoms are,

V_FWvolume in thermal free space, in cm of volume under standard conditions³；

V_LOWLower manifold volume in cm³；

T₁Is the temperature of the system manifold before helium is added to the sample tube, in units of K;

T_STD273.13K at standard temperature;

P₁pressure in mmHg of the system manifold before helium was added to the sample tube;

P₂of system manifolds after helium is added to sample tubesPressure, in mmHg.

In the experimental process, after the liquid nitrogen dewar bottle is lifted to the designated position, the bottom of the sample tube is soaked in the liquid nitrogen environment, and the volume of the cold free space (cold free space) can be obtained according to the pressure change before and after filling helium gas, and is expressed by the following equation (2):

in the above formula, the first and second carbon atoms are,

V_FCvolume of cold free space in cm of volume under standard conditions³；

T₂Raising the Dewar bottle to a specified position, filling helium gas until the temperature of the system manifold reaches equilibrium, wherein the unit is K;

P₃the dewar was raised to the specified position and filled with helium until the pressure of the sample vessel after equilibration was reached, in mmHg.

Note that the lower manifold volume V in the above two equations (1) and (2)_LOWThe total volume of the connecting pipe and the sample pipe which are connected with the manifold system connecting valve 3 after the manifold system connecting valve is closed. V calculated from equation (1)_FWIs the volume of the manifold system (i.e., the volume of the space between the manifold system connecting valve 3 to the manifold system 2 in fig. 1), and V is calculated from equation (2)_FCV is the actual measured volume of the sample tube and the connection end of the sample tube to the manifold (i.e. the space between the manifold system connection valve 3 and the sample tube 6 in fig. 1)_FWUsually well below V_FC. Thus, the volume V of the thermal free space is obtained according to equation (1) and equation (2), respectively_FWAnd volume V of cold free space_FCAnd not the volume of the sample tube at room temperature and liquid nitrogen temperature, respectively. In the original data output by the instrument after each experiment, V of each experiment can be intuitively obtained in each report_FWAnd V_FC。

It is apparent that after the sample is added to the sample tube, V is obtained by experimental measurement_FWAnd V_FCThe measurement value before the sample is added to the sample tube is changed accordingly. The V values before and after the sample (copper sheet) was added to the sample tube, which were obtained by a plurality of experimental measurements, are shown in Table 1_FWAnd V_FCNumerical values (converted to volume at 231.13K).

The volume V of the thermal free space before and after the addition of the sample obtained at different experimental times can be recorded in the form of Table 1_FWAnd volume V of cold free space_FCNumerical value (unit: cm)³)。

TABLE 1

	1	2	3	4	5	Mean value of
							V before addition of sample_FW
V after addition of sample_FW
							V before addition of sample_FC
V after addition of sample_FC

Volume V of thermal free space obtained according to Table 1_FWAnd volume V of cold free space_FCThe average of the values is multiplied by a correction factor determined from a standard substance of known density, usually copper, to give the volume of the sample. The true density of the measured sample can be calculated according to a density formula.

The utility model discloses can implement through following form:

(1) the method for increasing the sample dosage in the experiment by adopting a large-volume sample tube in the experiment is used for improving the cold free space V_FCA change in (c);

(2) the method can be applied to porous materials containing micropore, mesopore or macropore information;

(3) the sample to be tested may be in the form of a powder, film, fiber, block, or the like.

Claims

1. A device for testing the true density of a material based on a physical adsorption instrument comprises an adsorption instrument vacuum system (1), a manifold system (2), a manifold system connecting valve (3), a sample tube connecting port (4), a sample tube (5) and a Dewar flask cover (6), fill stick (7), liquid nitrogen (8), sample (9), sample cell sample room (10), P0 pipe (11) and dewar bottle (12), contain manifold system (2) and manifold system connecting valve (3) in adsorption apparatus vacuum system (1), manifold system connecting valve (3) are connected with sample cell connector (4), dewar bottle lid (6) are the lid of dewar bottle (12), be equipped with liquid nitrogen (8) in dewar bottle (12), adsorption apparatus vacuum system (1) is through P0 pipe (11) connection dewar bottle (12), sample cell (5) are connected with sample cell sample room (10), its characterized in that: the sample tube (5) provided with the filling rod (7) and the sample (9) is connected with the vacuum system (1) of the adsorption instrument through the sample tube connecting port (4), the Dewar flask cover (6) is covered, and the sample chamber (10) of the sample tube is of a cylindrical structure with the closed bottom end and can accommodate more samples.