Method of determining degree of impregnation of carbon fibre braids with pitches and device for its realisation

FIELD: chemistry.

SUBSTANCE: invention relates to field of producing carbon-carbon composite materials for various purposes, and is intended for comparative characteristic of impregnation of carbon fibre (CF) braids with melts of pitches, and can be used in improvement of technologies of producing carbon-carbon composite materials, possessing various properties, by modification or replacement of pitch binder and/or carbon fibre, for instance, in research laboratories, in particular, in carrying out laboratory work. To determine degree of impregnation of carbon fibre braids with pitches, carbon fibre braid is placed into glass tube in such a way that the end of braid protrudes from glass tube, and carbon fibres in braid are oriented along glass tube axis, with braid thickness being selected in such a way that it tightly fits glass tube, protruding end of carbon fibre braid is brought in contact with melted pitch and keep in such position, after which carbon fibre braid is extracted from tube and height of impregnation of carbon fibre braid with pitch is determined.

EFFECT: simplification and acceleration of determination are achieved.

1 ex, 3 dwg

 

The invention relates to the production of carbon-carbon composite materials for various purposes, is intended for comparative evaluation impregnation of bundles of carbon fibers melts Pekov and can be used in the development of production technology of carbon-carbon composite materials having different properties through modification or replacement of the pitch binder and/or carbon fibers, for example, in research laboratories, in particular, when conducting laboratory work.

Carbon fibers are characterized by a unique combination of physical, mechanical and chemical properties, combining high strength and chemical inertness, so you can use them to create composite materials not only common, but also aviation and space purposes. The strength and reliability of such materials, as well as simplification of the technological scheme for obtaining one depends on the nature of the interaction at the interface of carbon fibre/matrix. Functionalization of carbon fiber, modified binders, etc. promotes adhesion of carbon fibers to the matrix and to improve the mechanical properties of the material obtained.

One of the factors determining the strength of a composite material comprising a reinforcing component is the form of bundles of carbon fibers and polymer matrix in the form of pitch, is the ability of the binder to wet the carbon fiber, in other words, the affinity of carbon fiber and pitch. Wetting, in turn, determines the degree of impregnation of the fiber filler binder in the molding process and the uniformity of the material.

There is a method of determining the wetting of the carbon fibers of pitch, which was performed as a plate, Wilhelmi on the power tensiometer (Shornikova O. N. and other Wetting of the carbon fibers by the molten coal tar pitch // Chemical fiber. - 2012. No. 4. - S. 64-68). This method is adopted for the prototype. The essence of the method records Wilhelmi consists in immersing the plate with known geometrical parameters in the test fluid: when immersing the plate into a liquid it operates eject force F, which depends on the depth of immersion of the plate in the liquid. At the first stage of work was measured boundary angles of wetting of the carbon fibers of model fluids, samples monofilaments were placed in a hollow cylindrical holders, fixed with wire so that the length of the free end of the fiber not over 5 mm Holder secured on the scales and the sample was brought into contact with the model fluid. The measurements were carried out for 10 samples of fibers of the same type, within each measurement was performed 5 cycles of immersion/and the inclination of the fiber. In each cycle was recorded curve wetting - dependence of the force acting on the sample from the depth of immersion. Then the expected equilibrium wetting angles, the polar and dispersive components of the free surface energy of the fibers. Then determined the characteristics of the pitches. For this sample pitch was placed in a beaker with a diameter of 70 mm and height of 40 mm, so that the glass was half full. The glass electrode was placed in a thermostatted cell with a temperature of 160C. Next, the measured surface tension of melts of pitches by the method of the rings due Nui. For each sample was performed 10 measurements. Next was measured wetting angle Teflon plates molten pitch was calculated polar and dispersive components of the molten pitch. For each sample spent at least 5 measurements. Between measurements peck thermostatically 10 minutes with the lid closed.

This technology determine the wetting of the carbon fibers of pitch is very difficult, time consuming and requires a lot of time measuring process and the decryption process of the data. Another disadvantage of this method lies in the complexity of its hardware design.

In addition, the measurement of the wetting of the fibers of a polymeric binder (pitch) directly is not always possible due to the small diameters of the monofilaments and the viscosity of the binder.

The objective of the invention is the tsya simplification and acceleration of the process of determining the degree of impregnation of carbon fibers by pitches as well as simplifying the equipment to determine the degree of impregnation of carbon fibers by pitches.

The technical result is achieved by a method for determining the degree of impregnation of bundles of carbon fibers pitches, which is characterized by the fact that the harness carbon fiber is placed in a glass tube so that the end of the harness was made of a glass tube, and carbon fiber in the bundle are oriented along the axis of the glass tube, when the thickness of the harness is chosen so that it is tightly held in a glass tube, the protruding end of the bundle of carbon fibers is brought into contact with the molten pitch and survive in this position, then harness carbon fiber extracted from the tube and determine the height of the impregnation of the bundle of carbon fibers peck.

Technical result is achieved by setting to determine the degree of impregnation of bundles of carbon fibers pitches, which can be carried out the above method and which contains the furnace, the base with the possibility of placing it in an oven, a tray mounted on the base, and a holder for at least one vertically installed glass tube, located at the base on the tray with a vertical reciprocating movement.

The foregoing features and advantages of the invention will be clear from the following description of preferred examples with reference to the accompanying drawings, on which the same elements are denoted by identical positions:

in Fig.1 shows a diagram of the installation to determine the degree of impregnation of bundles of carbon fibers pitches in accordance with the present invention;

in Fig.2 is a diagram of a base installed on the tray and a holder in the original position in accordance with the present invention;

in Fig.3 is a diagram of a base installed on the tray and a holder in position when the protruding end of the bundle of carbon fibers is lowered into the molten pitch, in accordance with the present invention.

The basis of the method of determining the degree of impregnation of bundles of carbon fibers pitches in accordance with the present invention based on a capillary liquid (solution, melt) in the region between the carbon fibers collected in the harness. For carrying out the proposed method uses at least one glass tube 1, which is placed in harness 2 carbon fiber. The thickness of the wiring harness 2 is chosen so that it is tightly held within the glass tube 1. Carbon fiber tow 2 is oriented along the axis of the glass tube (almost parallel). The free end of the harness 2 carbon fiber, the speaker of the glass tube 1, is brought into contact with the impregnating liquid - molten pitch 4 and videris who are in this position for a fixed period of time. Because carbon fiber caused sizing, and there are defects, what would be the dense nor was packing carbon fiber bundle 2, there is a long and narrow space. If carbon fiber is wetted by molten pitch 4, due to the effect of capillary suction it will rise along the carbon fibers and fill the distance between them. If the packaging harness 2 carbon fiber is not dense, then the gravitational force exceeds the force of capillary suction, and the molten pitch will not impregnate harness carbon fibers. Then harness 2 carbon fiber removed from the glass tube 1 and determine the path of the molten pitch 4 in the Central part of the harness 2, i.e., the height of the impregnation harness 2 carbon fiber peck 4.

The above-described method can be implemented at the facility to determine the degree of impregnation of bundles of carbon fibers pitches, which contains the furnace 5 and the base 6, which is located with the possibility of placing in the oven 5. As the furnace 5 can be used in the drying Cabinet or muffle furnace, providing temperatures up to 350C. On the basis of 6 mounted bath 7 for pitch 4. Based 6 on the tray 7 is located with the vertical reciprocating movement of the holder 8 for at least one vertice is Ino installed glass tube 1.

Work on the installation to determine the degree of impregnation of bundles of carbon fibers pitches as follows.

Carbon fiber is cut the same length and put together, forming wiring harness 2. Received the harness 2 is placed in a glass tube 1 so that the end of the harness 2 protrudes from the glass tube. 1, and the carbon fiber bundle 2 were oriented along the axis of the glass tube 1, when the thickness of the harness 2 is chosen so that it is tightly held within the glass tube 1.

In the tub 7 fall asleep peck 4 and sets over it the holder 8 for the at least one glass tube 1. The holder 8 is fixed vertically at least one glass tube 1 so that the protruding end of the harness 2 carbon fiber was at some distance from the level of the pitch.

Base 6 with a tray 7, is filled with pitch 4, and the holder 8 with at least one glass tube 1 with a bundle of 2 carbon fiber is placed in a furnace 5, heated to a temperature of 80C. above the softening point of pitch (~190C). After melt pitch 4 additionally incubated for 30 minutes. After that, the holder 8 is lowered to such a level that the protruding end of the harness 2 carbon fiber come into contact with the molten pitch 4, and the edge of the glass tube 1 is positioned above the level of pitch 4. The holder 8 in this is ulozhenie fix and maintain. Then, the base 6 is extracted from the furnace 5, and the holder 8 is raised to its original position. After cooling harness 2 carbon fiber removed from the glass tube 1 and determine (e.g., tactile) height impregnation harness 2 carbon fiber peck 4.

The described method is proposed for comparative evaluation impregnation of bundles of carbon fibers melts Pekov, the results of which you can use when developing technologies for the production of carbon-carbon composite materials depending on their mechanical and operational properties through modification or replacement of the pitch binder and/or carbon fiber.

Example.

Setting to determine the degree of impregnation of bundles of carbon fibers pitches contains:

the base 6 is located with the vertical reciprocating movement of the holder 8 for glass tubes 1;

- glass tube 1 with an inner diameter of 8 mm (5 pieces);

- bath 7 for melting pitch 4;

oven 5, providing temperatures up to 350C.

Determination of the degree of impregnation of bundles of carbon fibers pecks at the facility was carried out as follows.

1. Sample preparation carbon fiber.

Carbon fiber cut length 100 mm and folded together into bundles 2 so that the resulting line is Naya density was 27,000 Tex.

The obtained carbon fiber bundles were placed in a glass tube 1 so that the end of the wiring harness 2 is performed from the side of the glass tube 1 at 10-13 mm. the ends of the wiring harness 2 podrachivala with scissors.

2. Preparation of the installation to determine the degree of impregnation.

In the tub 7 bombarded peck 4 and set the holder 8, which is secured 5 glass tubes 1 with a bundle of 2 carbon fiber so that the distance from the level of the pitch until the end of the harness 2 carbon fiber was 15-20 mm. Original position before performing the assay shown in Fig.2

3. Carrying out the determination of the degree of impregnation.

Base 6 with a tray 7 and the holder 8, in which is placed a glass tube 1 with the wiring 2 carbon fiber was placed in a furnace 5, heated to a temperature of 80C. above the softening point of pitch (~190C). After melt pitch 4 installing optional kept for 30 minutes. After that, the holder 8 is lowered to such a level that the ends of the wiring harness 2 carbon fiber were immersed in molten pitch 4, wherein the side of the glass tube 1 is positioned above the level of pitch 4 1-2 mm (see Fig.3). The position of the holder 8 recorded and kept for 2 hours. Then the base 6 was removed from the furnace 5 and the holder 8 is raised to its original position (see Fig.2).

After cooling, the wiring 2 carbon fiber was removed from the glass tubes 1 and defined (tactile way) height impregnation harness 2 carbon fiber peck 4.

This example confirms that the proposed method and installation allow you to simplify and accelerate the process of determining the degree of impregnation of bundles of carbon fibers pitches, as well as to simplify the apparatus and equipment and to reduce the operation of the decoding of the received data.

The above-described embodiment should in all respects be regarded as merely illustrative and not causing any restrictions. Therefore, can be used in other embodiments of the present invention and examples of implementation, which does not exceed the limits described here are essential attributes.

The method of determining the degree of impregnation of bundles of carbon fibers pitches, characterized in that harness carbon fiber is placed in a glass tube so that the end of the harness was made of a glass tube, and carbon fiber in the bundle are oriented along the axis of the glass tube, when the thickness of the harness is chosen so that it is tightly held in a glass tube, the protruding end of the bundle of carbon fibers is brought into contact with the molten pitch and survive in this position, then harness carbon fiber extracted from the tube and determine the height of the impregnation of the bundle of carbon fibers peck.



 

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