KR20210037494A - METHOD FOR MAKING PCS FIBER BUNDLE INFUSIBLE UNDER VACCUM ATMOSPHERE AND METHOD FOR FABRICATING SiC FIBER USING THE SAME - Google Patents

Abstract

The present invention relates to a method for making a polycarbosilane (PCS) fiber bundle infusible under a vacuum atmosphere, comprising: a step of creating a vacuum atmosphere in an infusibility chamber loaded with a PCS fiber bundle; and a step of injecting a cross-linking agent gas into the infusibility chamber at a temperature in the range of 150 to 300℃; and a method for manufacturing SiC fiber using the same. According to the present invention, the reaction rate between a cross-linking agent and a PCS fiber is significantly increased through an infusibility process performed on the PCS fiber bundle wound on a bobbin in a vacuum atmosphere. By increasing the flow rate and flow efficiency of the cross-linking agent, the cross-linking agent can effectively penetrate into the PCS fiber, thereby increasing process efficiency and process easiness. In addition, the excellent mechanical properties of the final product, SiC fiber, can also be secured.

Description

PCS fiber bundle incompatibility method under vacuum atmosphere and method of manufacturing SiC fiber using the same {METHOD FOR MAKING PCS FIBER BUNDLE INFUSIBLE UNDER VACCUM ATMOSPHERE AND METHOD FOR FABRICATING SiC FIBER USING THE SAME}

The present invention relates to a method for infusible PCS fiber bundles and a method for manufacturing SiC fibers using the same, and more particularly, in a vacuum atmosphere, the PCS fibers are infused with a bundle wound around a bobbin to remarkably increase the reaction rate of the crosslinking agent and the PCS fibers, PCS fiber bundles in a vacuum atmosphere that can increase the flow rate and flow efficiency of the crosslinking agent so that the crosslinking agent can effectively penetrate into the PCS fiber, thereby increasing process efficiency and ease of process, and securing excellent mechanical properties of the final product, SiC fiber. It relates to an incompatibility method and a method of manufacturing SiC fibers using the same.

Silicon carbide (SiC) is a representative non-oxide-based ceramic material and has excellent heat resistance, oxidation resistance, and chemical resistance at high temperatures, and thus it is increasingly important as a material that can be used in extreme environments such as high temperature, high pressure or acidic atmosphere.

Silicon carbide can be used in various forms, such as fibers, plates, and porous bodies, and especially in the case of fibrous materials, it is expected to be applied to catalysts and catalyst supports, high-temperature insulation materials, diesel filter materials, etc. through differentiation of the structure or shape of the fibers. . In particular, it is a material that can be used in extreme environments where existing organic or inorganic materials are difficult to access, such as filter material for high temperature extreme environments, for example, filtration and recovery of acidic gas at high temperature. .

In order to form a ceramic material into a fibrous shape, a method of melting-spinning the ceramic material by heating it to 1500°C or higher is generally used. However, since the SiC material has a melting point of 1800° C. or higher, it is difficult to melt spinning by heating a conventional SiC material. Therefore, SiC fiber is obtained by heating and melting a ceramic precursor polycarbosilane ('PCS'), a polymer that is converted to ceramic through thermal decomposition, at 200 to 300°C, and then spinning to produce PCS fibers having a fibrous shape. Thereafter, it is prepared by heat treatment at a temperature of 1000° C. or higher in an inert atmosphere to induce thermal decomposition.

However, PCS fibers basically have thermoplastic properties, and when heat is applied to convert them into ceramics, they soften and melt and lose their shape. Therefore, the SiC fiber manufactured through the thermal decomposition process of the PCS fiber as described above does not properly maintain the fiber shape and it is difficult to exhibit a function as a fiber.

To solve this problem, an incompatibility process for converting the properties of the PCS fiber to thermosetting so that it does not soften or melt even when heat is applied to the PCS fiber has been proposed. The generally used incompatibility process is low molecular weight by contacting PCS fibers with crosslinking agent gases such as air, oxygen, ozone, and halogen under atmospheric pressure (760 torr) to connect and stabilize functional groups in the polymer PCS through a crosslinking reaction. This is to prevent the monomers or oligomers from being softened and melted or volatilized by heat. Factors that determine the infusible efficiency of PCS fibers in the infusible process are the reaction rate of the crosslinking agent gas and the PCS fibers, and whether or not the crosslinking agent gas penetrates according to the location of a large amount of PCS fiber bundles.

However, according to the conventionally used incompatibility process, the reaction rate between the crosslinking agent gas and the PCS fiber is not fast enough, and the time required for incompatibility is very long, such as about 48 hours or more.

In addition, the PCS fiber that is introduced into the incompatibility process is melt-spun PCS, and it is simultaneously wound on the bobbin and put into the subsequent process.When the PCS fiber is spun and wound around the bobbin, the crosslinking agent gas penetrates as the fibers are firmly adhered to each other. It is difficult to react with the PCS fiber. That is, according to the conventional incompatibility process, the crosslinking agent gas is changed depending on the position of the PCS fiber bundle wound around the bobbin, that is, the penetration of the crosslinking agent gas on the surface, the center and the bottom of the bundle. Because it is difficult to penetrate, uniform incompatibility cannot be achieved. Therefore, in order to achieve uniform incompatibility over the entire fiber, the PCS fiber bundle wound around the bobbin must be repeated from the bobbin to perform the incompatibility process, and then wound on the bobbin again. In this way, in the process of winding and rewinding the fiber on the bobbin, fiber damage may occur and workability may be deteriorated, and as a result, the mechanical strength of the SiC fiber, which is a final product, may be lowered.

Accordingly, there is still a need for a method that can increase the efficiency of manufacturing the final product, SiC fiber, by increasing the incompatibility efficiency by infusible PCS fiber in a more effective and easy way.

It is an object of the present invention to provide a method for infusible PCS fiber bundles and a method for manufacturing SiC fibers using the same. In particular, the reaction rate of a crosslinking agent and PCS fibers is controlled through an incompatibility process performed on a PCS fiber bundle wound around a bobbin in a vacuum atmosphere. A vacuum atmosphere that can significantly increase the flow rate and flow efficiency of the crosslinking agent so that the crosslinking agent can effectively penetrate into the PCS fiber to increase process efficiency and process ease, and also secure excellent mechanical properties of the final product, SiC fiber. It is to provide a method for incompatibility of PCS fiber bundles and a method of manufacturing SiC fibers using the same.

An embodiment of the present invention for solving the above problem provides a method for infusible PCS fiber bundles, the method comprising: creating a vacuum atmosphere in an infusible chamber in which polycarbosilane (PCS) fiber bundles are charged; And injecting a crosslinking agent gas into the infusible chamber at a temperature in the range of 150 to 300°C.

In addition, another embodiment of the present invention for solving the above problem provides a method of manufacturing a SiC fiber, the method comprising the steps of incombusting the PCS fiber bundle according to the method of incompatibility of the PCS fiber bundle of the above-described embodiment; And thermally decomposing the infused PCS fiber bundle by heat treatment at a temperature in the range of 1000 to 2000°C.

According to the present invention, the reaction rate between the crosslinking agent gas and the PCS fiber is increased compared to the conventional PCS fiber incompatibility process, so that the incompatibility completion time is significantly shortened from about 48 hours to about 3 hours, thereby reducing the efficiency of the PCS fiber incompatibility process. It can be increased, and accordingly, the process efficiency of manufacturing the final product, SiC fiber, can be improved.

In addition, the SiC fiber produced according to the present invention may have excellent properties that are uniform and well-maintained, and a smooth surface.

In addition, since the flow rate and flow efficiency of the crosslinking agent is increased, the crosslinking agent gas is effectively penetrated regardless of the position of the PCS fiber bundles wound around the bobbin, so that the PCS fiber can be put into the infusible process as it is in the wound bobbin. The infusible process can be completed without the process of winding and rewinding the PCS fiber on the bobbin, and the subsequent heat treatment process can be performed without a separate additional process. Accordingly, it is possible to manufacture SiC fibers having excellent mechanical strength by minimizing damage to the fibers occurring in the process of winding and rewinding the fibers on the bobbin, and improves process ease and efficiency.

1 shows a picture of a PCS fiber immobilized according to an embodiment of the present invention.
2 shows a photograph of a PCS fiber wound around an infused bobbin according to an embodiment of the present invention.
3 shows a photograph of a SiC fiber bundle prepared according to an embodiment of the present invention.
4 shows a thermogravimetric graph of SiC fibers manufactured according to Examples and Comparative Examples.
5(a) shows the tensile strength of 10 types of SiC fibers manufactured by infusible under normal pressure according to a comparative example, and FIG. Indicates the tensile strength of

Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings in order to describe in detail enough that a person having ordinary knowledge in the technical field of the present invention can easily implement the technical idea of the present invention. In the following description, there are many specific details such as specific elements, etc., which are provided to help a more general understanding of the present invention, but it is common knowledge in the art that the present invention can be practiced without these specific details. It is self-evident to those who have. Further, in describing the present invention, when it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, a detailed description thereof will be omitted.

In an embodiment of the present invention, a method of incompatibility of a PCS fiber bundle includes: creating a vacuum atmosphere in an incompatibility chamber into which a polycarbosilane (PCS) fiber bundle is charged; And injecting a crosslinking agent gas into the infusible chamber at a temperature in the range of 150 to 300°C.

PCS fibers can be produced by heating and melting PCS, and then spinning the melted PCS to form a fibrous shape.

The fiber may be formed by a method known in the art, and for example, may be performed by at least one method selected from the group consisting of melt spinning, electrospinning, and mellon spinning.

The spun PCS fibers can be used in a subsequent process as a bundle wound around a bobbin.

In this embodiment, a bundle of PCS fibers wound around a bobbin may be charged into the infusible chamber, and a vacuum atmosphere may be created in the infusible chamber.

The degree of vacuum in the vacuum atmosphere may be 10 torr or less, preferably more than 0 torr and 10 torr or less. When the degree of vacuum exceeds 10 torr, the movement of the crosslinking agent gas that induces incompatibility decreases, so that the speed of penetration or reaction into the PCS fiber is slowed, and the induction of incompatibility is not improved as desired.

The steps of creating a vacuum atmosphere include: i) removing air in the infusible chamber using a vacuum pump, ii) injecting nitrogen into the infusible chamber, and iii) vacuuming nitrogen in the infusible chamber. It may include a step of removing using a pump, and the cycle consisting of steps i), ii), and iii) may be repeated two or more times.

By creating a vacuum atmosphere in the chamber in which the infusible process is performed, the reaction rate of the crosslinking agent gas and the PCS fiber, the flow rate and flow efficiency of the crosslinking agent gas are remarkably increased, thereby maximizing the efficiency of the infusible process.

A crosslinking agent gas may be injected into the infusible chamber in which a vacuum atmosphere is formed to react with the PCS fiber.

The crosslinking agent gas that may be used in the present embodiment may include one or more selected from the group consisting of air, oxygen, ozone, and halogen gas.

Halogen can include fluorine, chlorine, bromine and iodine.

The concentration of the crosslinking agent gas may range from 10 to 80%. When the concentration of the crosslinking agent gas is less than 10%, the incompatibility rate is too slow, so there is no meaning of the composition of the crosslinking agent gas, and when the concentration of the crosslinking agent gas exceeds 80%, the incompatibility rate is no longer improved by increasing the concentration.

The crosslinking agent gas may be continuously injected while maintaining a predetermined degree of vacuum, or may be intermittently injected at a predetermined time interval.

The crosslinking agent gas penetrates the fiber strands in the PCS fiber bundle and causes a crosslinking reaction to stabilize the functional groups contained in the PCS, so that the low molecular weight monomer or oligomer contained in the high-molecular PCS is softened by heat during the high temperature heat treatment process for the manufacture of SiC fibers. PCS fibers can be converted into thermosetting polymer forms so that they do not become volatile, melt, or volatilize.

When the crosslinking agent gas is injected, the infusible chamber may be heated to a temperature in the range of 150 to 300°C. When the temperature is less than 150°C when the crosslinking agent is injected, the crosslinking reaction by the crosslinking agent does not occur and thus incompatibility does not proceed, and when the temperature exceeds 300°C, there is no effect of improving the crosslinking reaction rate any more due to an increase in temperature.

The crosslinking agent gas and the PCS fiber may be used in a weight ratio of 0.2:1 to 1:1. When the weight ratio of the crosslinking agent gas and the PCS fiber is less than the above range, incompatibility by the crosslinking agent gas does not proceed, and when it exceeds the above range, the infusible rate by the crosslinking agent gas is no longer improved.

As described above, since the method of incompatibility of the PCS fiber bundle according to the present embodiment is performed in a vacuum atmosphere, the reaction rate between the crosslinking agent gas and the PCS fiber is accelerated, so that the incompatibility may be completed within about 3 hours. While the conventional infusible method typically takes 48 hours or more, the infusible method of the PCS fiber bundle according to the present embodiment can significantly reduce the infusible process time compared to the prior art.

In addition, according to the method of incompatibility of the PCS fiber bundle according to the present embodiment, the flow rate and flow efficiency of the crosslinking agent gas are increased, so that it can uniformly and effectively penetrate the fiber strand regardless of the position of the fiber strand in the PCS fiber bundle. In other words, even in the case of a bundle of PCS fibers wound around a bobbin that is difficult to react with the PCS fiber due to the penetration of the crosslinking agent gas due to tight adhesion between the fibers, the penetration of the crosslinking agent gas is made evenly regardless of the positions of the surface, center and bottom. I can.

Therefore, the PCS fiber can be put into the infusible process as it is in the wound bobbin, thus completing the infusible process without winding and rewinding the PCS fiber on the bobbin during the SiC fiber manufacturing process, and performing the subsequent heat treatment process without any additional process. can do.

Accordingly, it is possible to manufacture SiC fibers having excellent mechanical strength by minimizing damage to the fibers occurring in the process of winding and rewinding the fibers on the bobbin, and improves process ease and efficiency.

A method of manufacturing a SiC fiber according to another embodiment of the present invention includes the steps of incompatibility of the PCS fiber bundle according to the method of incompatibility of the PCS fiber bundle of the above-described embodiment; And thermally decomposing the infused PCS fiber bundle by heat treatment at a temperature in the range of 1000 to 2000°C.

In order to manufacture SiC fibers, the PCS fiber bundles infused according to the above-described embodiment may be thermally decomposed by heat treatment at a temperature in the range of 1000 to 2000°C, preferably in the range of 1500 to 1800°C.

In one embodiment, the heat treatment may be performed for 30 minutes to 5 hours.

In addition, it is preferable that the heat treatment is performed in an inert atmosphere.

By performing the high-temperature heat treatment as described above, PCS fibers, which are organic polymers, can be formed into SiC fibers, which are inorganic materials, through organic-inorganic conversion.

According to the SiC fiber manufacturing method of this embodiment, since the incompatibility efficiency of the PCS fiber as the starting material is remarkably high, the yield of the SiC fiber formed therefrom can be greatly increased, and SiC fiber having excellent morphological properties can be produced. have. In addition, since it is possible to minimize the damage to the fibers occurring in the process of winding and rewinding the fibers when going through the PCS fiber incompatibility process, the finally produced SiC fiber has excellent mechanical strength.

Hereinafter, the present invention will be described in more detail by examples. However, the following examples are only illustrative of the present invention, and the scope of the present invention is not limited to the following examples.

[Example]

1. Incompatibility of PCS fiber bundles

PCS has a molecular weight of 3266, a ceramic (SiC) conversion yield of 61% by weight when heat-treated to 1000°C, a softening point of 167°C, and a melting point of 195°C were used. The melt spinning of the PCS was carried out in a 50 μm diameter nozzle. After holding in a vacuum at 120° C. for 1 hour, it was kept in a vacuum (0.25 bar) at 220° C. for 2 hours to completely melt. The PCS in a melted state at 250° C. was wound around a bobbin rotating in a fibrous shape (speed of 400 rpm) and spun.

A bundle of PCS fibers wound around a bobbin was charged into an infusible chamber, and a vacuum atmosphere was created with a vacuum degree of 10 torr or less. To create a vacuum atmosphere, repeat the process of removing air in the incompatibility chamber using a vacuum pump, injecting nitrogen into the incompatibility chamber, and removing nitrogen in the incompatibility chamber using a vacuum pump 2-3 times. It was done by performing. Subsequently, the infusible chamber is heated to a temperature of 200 to 300°C, and oxygen gas (concentration %) is continuously or intermittently injected as a crosslinking agent gas and maintained for 3 hours, so that the oxygen gas reacts with the functional groups of the PCS, resulting in a low molecular weight monomer. Alternatively, a crosslinking reaction was performed between oligomers to complete the incompatibility of the PCS fiber bundle.

1 shows a picture of a PCS fiber immobilized according to an embodiment of the present invention. Referring to FIG. 1, the crosslinking agent gas effectively penetrates the fiber strands regardless of the position of the fiber strands in the PCS fiber bundle by the infusible process in a vacuum atmosphere according to the present invention, and all of the surface, center, and bottom portions of the fiber bundle are uniform. As it turns yellow, it can be seen that the incompatibility is complete.

2 shows a photograph of a PCS fiber wound around an infused bobbin according to an embodiment of the present invention. Referring to FIG. 2, when the PCS fibers are spun and wound around the bobbin, there is a point that it is difficult to react with the PCS fibers due to the penetration of the crosslinking agent gas because the fibers are firmly adhered to each other. Even when it is wound around this bobbin, it can be confirmed that the incompatibility is complete while uniformly turning yellow.

2. SiC fiber manufacturing

The PCS fiber infused in 1 above was heat-treated at a maximum of 1500°C in an inert atmosphere under atmospheric pressure to induce a pyrolysis reaction to prepare a SiC fiber.

3 shows a photograph of a SiC fiber bundle prepared according to an embodiment of the present invention. Referring to FIG. 3, the infusible efficiency was remarkably increased through the infusible process in a vacuum atmosphere according to the present invention, so that a flexible SiC fiber having a round cross section and a smooth surface was manufactured. The diameter of the SiC fiber is about 10-15 μm.

3. Thermogravimetric analysis and tensile strength analysis of SiC fiber

The thermal weight and tensile strength of SiC fibers prepared according to Examples and Comparative Examples were measured.

4 shows a thermogravimetric graph of SiC fibers manufactured according to Examples and Comparative Examples. Comparative Example 1 differs from the Example in that the infusible process was performed under atmospheric pressure, and Comparative Example 2 differs from the Example in that the infusible process was not performed. That is, in Examples, SiC fibers manufactured through an infusible process in a vacuum atmosphere having a vacuum degree of 10 torr or less according to the above method are shown, and Comparative Example 1 shows SiC fibers manufactured through an infusible process under atmospheric pressure (760 torr). , Comparative Example 2 shows a SiC fiber manufactured without going through an infusible process.

4, in the case of the SiC fiber prepared by pyrolyzing the non-infusible PCS fiber of Comparative Example 2, the SiC yield was 52.24% by weight, and the SiC prepared by pyrolysis of the infusible PCS fiber under atmospheric pressure of Comparative Example 1 In the case of the fiber, the SiC yield was 74.44% by weight, and in the case of the SiC fiber prepared by pyrolyzing the PCS fiber infused in a vacuum atmosphere having a vacuum degree of 10 torr or less according to the Example, the SiC yield was 90.61% by weight. From the results of FIG. 4, it can be seen that the infusible efficiency of the PCS fibers in accordance with the present invention is increased in a vacuum atmosphere with a vacuum degree of 10 torr or less, and the yield of the final product, the SiC fibers, can be remarkably improved.

5 shows the tensile strength of SiC fibers prepared according to Comparative Examples (a) and (b). 5(a) shows the tensile strength of 10 types of SiC fibers manufactured by infusible under normal pressure according to a comparative example, and FIG. 5(b) shows 7 types of SiC fibers manufactured by infusible under vacuum according to an example. Indicates the tensile strength of

Referring to FIG. 5, the average tensile strength of SiC fibers prepared by heat treatment (pyrolysis) of PCS fibers subjected to relatively vacuum incompatibility treatment due to high infusible efficiency under vacuum atmosphere was found to be 0.21 GPa high.

The present invention is not limited by the above-described embodiments and the accompanying drawings, and it is common in the technical field to which the present invention pertains that various substitutions, modifications, and changes are possible within the scope of the technical spirit of the present invention. It will be obvious to those who have knowledge.

Claims (10)

Creating a vacuum atmosphere in the infusible chamber into which the polycarbosilane (PCS) fiber bundles are charged; And
Including the step of injecting a crosslinking agent gas into the incombustibility chamber at a temperature in the range of 150 ~ 300 ℃
Method of incompatibility of PCS fiber bundles.
The method of claim 1,
The vacuum atmosphere in the incompatibility chamber has a vacuum degree of 10 torr or less.
Method of incompatibility of PCS fiber bundles.
The method of claim 1,
The PCS fiber bundle is wound around a bobbin and charged into the incompatibility chamber.
Method of incompatibility of PCS fiber bundles.
The method of claim 1,
The step of creating the vacuum atmosphere,
I) removing air in the incompatibility chamber using a vacuum pump,
Ii) injecting nitrogen into the infusible chamber, and
Iii) removing nitrogen in the infusible chamber using a vacuum pump,
The cycle consisting of steps i), ii), and iii) is repeated two or more times.
Method of incompatibility of PCS fiber bundles.
The method of claim 1,
The crosslinking agent gas comprises at least one selected from the group consisting of air, oxygen, ozone and halogen gas.
Method of incompatibility of PCS fiber bundles.
The method of claim 1,
The crosslinking agent gas is continuously injected while maintaining a predetermined degree of vacuum, or intermittently injected at a predetermined time interval.
Method of incompatibility of PCS fiber bundles. The method of claim 1,
The crosslinking agent gas penetrates the fiber strands in the PCS fiber bundle and causes a crosslinking reaction to stabilize the functional groups contained in the PCS.
Method of incompatibility of PCS fiber bundles.
The method of claim 1,
By the method of incompatibility of the PCS fiber bundle, the PCS fiber bundle is incompatible within a time period of 3 hours or less.
Method of incompatibility of PCS fiber bundles.
Incompatibility of the PCS fiber bundle according to any one of claims 1 to 8 according to the method of incompatibility of the PCS fiber bundle; And
Including the step of thermally decomposing the infused PCS fiber bundle by heat treatment at a temperature in the range of 1000 ~ 2000 ℃
SiC fiber manufacturing method.

The method of claim 9,
The heat treatment is performed under atmospheric pressure and in an inert atmosphere.
SiC fiber manufacturing method.

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