RU2642009C2 - Method of estimation of space materials stability to impact of cosmic space factors - Google Patents

Abstract

FIELD: testing equipment.

SUBSTANCE: invention relates to the field of testing polymeric materials that are included into the structure of space crafts (SC). In the proposed method material specimens are exposed within a specified period of time on the surface of SC, then are placed in a container which, in turn, is placed in a transport container (zip lock in space) and they are return to Earth. In a vacuum chamber with a controlled inert atmosphere, the containers are opened and specimens are taken from them, each of which is placed in a separate sealed tank. Then, under laboratory conditions, changes in the properties of specimen materials are determined. The pressure of inert atmosphere in the vacuum chamber is maintained above the ambient pressure.

EFFECT: increasing the reliability of test results by practical exclusion of the influence of the Earth's atmosphere on them.

1 dwg

Description

The invention relates to the field of testing of polymeric materials after exposure to space factors (PCF), in particular deep vacuum, electromagnetic radiation, proton, electron, cold plasma, atomic oxygen flows, namely, the evaluation of the durability of materials exposed to the outer surfaces of spacecraft (SC) for a long time ) Polymeric materials are part of various products of spacecraft, for example thermoregulatory coatings, screen-vacuum thermal insulation, mechanical structures and solar cells.

A known method for assessing the resistance of space technology materials to the effects of outer space factors is that samples of the test materials are placed on the surface of the spacecraft, exposed for a specified period, placed in a container that is not sealed, and then returned to Earth, where in the laboratory conditions determine the change in the properties of the tested materials, by which they are judged on their durability [1].

The disadvantage of this method is the inaccurate reproduction of the effects of the space environment on the tested materials, since when transporting them to the Earth they contain chemically active particles formed in polymers under the influence of outer space factors, which, when exposed to atmospheric air, can enter into chemical reactions with molecular oxygen, which can lead to thermal oxidative degradation.

A known method for evaluating the resistance of space technology materials to the effects of outer space factors (see patent RU No. 2238228, C1, March 25, 2003, IPC7 B64G 1/66, G01N 33/00), which consists in the fact that samples of the tested materials are placed on the surface of the space apparatus, expose them for a specified period, place them in a container, which is placed in a transport container sealed in space and return them to Earth, where in a laboratory environment the transport container is placed in a vacuum chamber with a controlled in an inert medium, after which the transport container and the container with the samples are opened, then the samples are removed and placed in separate sealed canisters, followed by testing of the samples also in a vacuum chamber, by which the change in the properties of the tested materials is determined and their stability is judged by them .

The disadvantage of this method (prototype) is the inaccurate reproduction of the effects of the space environment on the test materials, caused by the possibility of air penetrating into the internal cavity of the canisters with samples during storage before testing, which can affect the change in the properties of the samples exposed in open space.

The problem to which the present invention is directed is the practical exclusion of the influence of the Earth’s atmosphere on space-tested samples stored in sealed canisters.

The problem is solved in that in the method for assessing the resistance of space technology materials to the effects of outer space factors, samples of the tested materials are placed on the surface of the spacecraft, exposed for a predetermined period, placed in a container, which, in turn, is placed in a sealed in space transport container and return them to Earth, where the containers are placed in a vacuum chamber with a controlled inert medium and open them with the extraction of samples, then Each sample is placed in a separate sealed canister, followed by laboratory testing of samples to determine changes in their properties, which are used to judge the resistance of materials. Before placing samples in separate sealed canisters, environmental parameters are measured and an inert pressure is created in a vacuum a chamber satisfying the condition:

p _is > p _os

where p _uc - the pressure of the inert medium;

p _os - environmental pressure.

The essence of the invention is to provide in the case with samples of inert gas pressure is obviously higher than the pressure of the surrounding air, which excludes the possibility of penetration of molecular oxygen of the air into the internal cavity of the case.

Contact with air affects the change in the properties of samples exposed in open space. This is especially true for polymers [2]. The properties of the polymer material after exposure to PCF depend to a large extent on molecular oxygen, in the presence of which chain radiation and photochemical oxidation processes occur. Under these conditions, the time of contact of the exposed samples with the Earth’s atmosphere during ground research should not exceed the time of establishing the equilibrium oxygen concentration in the material. The limiting contact time with atmospheric oxygen is characteristic for each polymer. It was experimentally established that the molecular oxygen of space does not exert a particular effect on the samples for 3 months. Consequently, the transport container must be returned to Earth no later than 3 months later.

According to [3], a “container”, being under vacuum (it was sealed manually using fasteners) and located, in turn, in the Earth’s atmosphere, has the property of leakage, i.e. air begins to penetrate into the internal cavity of the containers.

It is also necessary to take into account the fact that the greater the pressure difference inside the cavity of the containers and the Earth’s atmosphere, the more intensive the leakage process occurs.

We should not forget that the Earth’s atmosphere is an environment that is constantly in dynamics. Analysis of statistical data on the pressure of the Earth’s atmosphere showed the following: the lowest pressure is ~ 715 mm Hg and the highest pressure is ~ 770 mm Hg. (Moscow region).

Given the foregoing, we conclude that in order to virtually eliminate the penetration of air into the internal cavity of the canister and to preserve the sample, it is necessary to seal the canister at an inert pressure of ~ 775 mm Hg.

A diagram of a vacuum chamber for depressurizing transport containers is shown in FIG. The communication systems are connected to the vacuum chamber 1: vacuum 9, purification and gas circulation system 10. The vacuum chamber is equipped with:

- sight glass 2;

- backlight glass 3;

- light source 4;

- a shell 5;

- gloves 6;

- manhole cover 7;

- shutter 8.

The depressurization of the transport container and the container with samples includes the following operations:

1) loading the transport container into the vacuum chamber;

2) fixing the gloves (closing the shutter) of the operator in the closed position, protecting them from damage by the differential pressure during the initial pumping of the vacuum chamber;

3) high-vacuum pumping chamber to a pressure of 10 ^-5 ... 10 ^-4 mm RT.article during few hours;

4) cut-off of the vacuum chamber from the vacuum system;

5) inlet into the vacuum chamber of an inert gas (argon) from a high-pressure cylinder to atmospheric pressure;

6) circulation pumping of gas from the vacuum chamber through the cleaning system for several hours to clean the entire gas volume and bring the entire system to a stationary state;

7) bringing the operator’s gloves to working position;

8) carrying out operations to extract samples from containers and layout them on pencil cases using a hand tool with an operator in gloves;

9) increasing the pressure in the vacuum chamber to ~ 775 mm Hg;

10) sealing of pencil cases;

11) shutdown and sealing of the gas circulation and purification system;

12) opening the flange of the box and removing the sealed canisters;

13) closing the flange of the box.

For fore-vacuum and vacuum pumping in a vacuum chamber, you can use the pumps AVZ-20 and the unit AVP-250 with a speed of 1000 l / s. Leak control is carried out by the leak detector PTI-14. Argon is used as an inert gas. The system for cleaning and circulating gas in a vacuum chamber is similar to the devices used in the prototype (see patent RU No. 2238228, C1, March 25, 2003, IPC7 B64G 1/66, G01N 33/00).

Information sources

1. S.L.B. Woll, H.G. Pippin, M.A. Stropki. S. Clifton. Materials on International Space Station Experiment (MISSE) // Proc. 8th International Symposium on "Materials in a Space Invironment", 5th Intemation Conference on "Protection of Materials and Structures from the LEO Space Environment". Arcachon-France. 2000.

2. K.K. De Gron, J.D. Gummow Effect of Air and Vacuum Storage on the Tensile Properties of X-Ray Exposed Aluminazed - FEP // Proc. 8th International Symposium on "Materials in a Space Invironment", 5th Intemation Conference on "Protection of Materials and Structures from the LEO Space Environment". Arcachon-France. 2000.

3. B.I. Korolev and others. "Fundamentals of vacuum technology." M., L .: Energy, 1957. - 251 p.

Claims (4)

A method for assessing the resistance of space technology materials to the effects of outer space factors, namely, that the samples of the tested materials are placed on the surface of the spacecraft, exposed for a predetermined period, placed in a container, which, in turn, is placed in a transportable container in space container and return them to Earth, where these containers are placed in a vacuum chamber with a controlled inert environment and open them with the extraction of samples, then each of the samples is placed in a separate sealed canister, followed by laboratory testing of samples to determine changes in their properties, which are used to judge the resistance of materials, characterized in that before placing the samples in separate sealed canisters, environmental parameters are measured and created in a vacuum the chamber inert pressure, satisfying the condition: p _is > p _OS , where p _uc - the pressure of the inert medium, p _os - environmental pressure.

Images