KR20180082077A - Method of manufacturing mat-typed silicon carbide fiber - Google Patents

Abstract

The present invention relates to a method of manufacturing mat type silicon carbide (SiC) fibers. According to the present invention, mat type SiC fibers are manufactured through a simplified process, thereby reducing manufacturing costs of the fiber. The method of manufacturing mat type SiC fibers comprises: a step which synthesizes polycarbosilane (PCS); a step which spins the synthesized PCS by blowing high-temperature air to the same at a fast speed to form mat type PCS fibers; a step in which the mat type PCS fibers are heated at the temperature equal to or higher than a softening point of the PCS and the temperature equal to or lower than a melting point for t1 hours to induce surface fusion between the fibers in the mat type PCS fibers; a stabilizing step in which the mat type PCS fibers are heated at the temperature equal to or lower than the softening point of the PCS for t2 hours to render the mat type PCS fibers infusible; and a heat processing step in which the stabilized mat type PCS fibers are thermally treated under the inert gas atmosphere to covert the mat type PCS fibers into mat type SiC fibers.

Description

METHOD OF MANUFACTURING MAT-TYPED SILICON CARBIDE FIBER [0002]

This technology relates to the production of silicon carbide (silicon carbide, SiC) fiber, which is a ceramic fiber, and more specifically to an efficient manufacturing process which can lower the unit cost of the fiber produced by manufacturing the mat type SiC fiber through the process simplification Technology.

Silicon carbide (SiC) fibers have recently attracted much attention as various component materials in various logistics fields. Also, as a fiber reinforced material of a composite material using a polymer or ceramics as a matrix, it is being utilized in various industrial fields, and its application range is gradually increasing.

The SiC fibers may be spun into linear fibers and then processed into a woven material or the like or used as a mat type. For example, matte type SiC fibers can be utilized in burners with porous ceramic radiant burner plates and the like. The SiC fiber is excellent in emissivity, excellent in high-temperature stability and durability, and thus can be optimized as a ceramic fiber for radia- tion.

The mat-type SiC fibers can be usually prepared by melt-spinning the PCS precursor (synthesized PCS) by a melt blowing method, followed by a stabilization step and a heat treatment step. However, by blowing the air by blowing the PCS precursor through the melt blowing method, the adhesion strength between the surfaces of the fiber-fiber to be radiated is weak and the density is low, so that it can not be completely manufactured with the mat-shaped SiC fiber. Therefore, in order to produce a mat-type SiC fiber, a separate technical means must be taken in order to realize a mat shape of an integrally bonded form.

In order to realize such a mat shape of SiC fibers, Korean Patent Laid-Open Publication No. 10-20009-0082797 discloses a method of heating a PCS fiber spun by a melt-blowing method by warm pressing by a so-called warm-roller to realize a mat shape . However, since this method introduces a separate pressing means into the process, there is a problem in terms of simplification of the process, that is, efficiency.

In addition, the above-mentioned mat type SiC fiber for the radiation needs to maintain the porosity for passing the gas. However, the method of the above-mentioned patent discloses mechanical compression of PCS fibers to provide contact force between the final fibers, which obstructs the flow of air, making it difficult to uniformly stabilize the gas, and the gas generated during the stabilization process can not escape directly to the outside Reacting with the fiber may damage the properties of the stabilized fiber. Further, in order to further improve the breathability of the mat as well as to impair the porosity of the mat to be manufactured, an additional process may be required such as a separate piercing process after the production of the mat-type SiC fiber.

It is an object of the present invention to provide a method of manufacturing a mat type SiC fiber which can solve the problems of the conventional process described above, simplify the process, and sufficiently secure the porosity of a mat manufactured by a simple process.

A method of manufacturing a mat-type SiC fiber according to an embodiment of the present invention includes: synthesizing a polycarbosilane (PCS); Forming matted PCS fibers by spinning the synthesized PCS at a high temperature while blowing air at a high temperature; I) heating the mat-type PCS fibers during a period of time t1 for at least a softening point of the PCS and a temperature below the melting point to induce melt adhesion of the fibers between the fibers in the mat-type PCS fibers; And ii) insolubilizing said mat type PCS fiber for a time of less than t2 hours at a temperature below the softening point; And a heat treatment step of converting the stabilized mat type PCS fiber into a mat type SiC fiber by heat treatment under an inert gas atmosphere.

T1 is less than 5 minutes, and t2 is preferably about 1 to 10 hours.

Meanwhile, the heat treatment may be performed at a temperature of 1000 to 1200 ° C.

The PCS is irradiated onto a conveyor belt on which a plurality of pins are formed, and the conveyor belt may include a suction device for urging the PCS fibers, which are radiated on the conveyor belt, in a direction perpendicular to the conveyor belt surface.

According to the method for producing the mat type SiC fiber according to the present invention, it is possible to improve the adhesion between the fiber surfaces only by controlling the temperature in the stabilization process, which is an essential process in the production process of the SiC fiber, It is possible to simplify the process.

In addition, since the mechanical compression force is not applied to the PCS fiber to prepare the PCS fiber mat after the melt spinning, sufficient porosity and damage such as shape retention of the fibers can be eliminated. Further, if necessary, a separate perforation process after SiC fiber fabrication can be eliminated by forming a number of fins that can penetrate the mat on the conveyor belt, as described below.

FIG. 1 is a conceptual diagram illustrating a concept of a PCS melt spinning process according to an embodiment of the present invention. Referring to FIG.
FIG. 2 is a temperature graph showing the temperature change in the stabilization step according to an embodiment of the present invention. FIG.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. It should be noted that the following description is only an exemplary description for explaining the technical idea of the present invention, and the technical idea of the present invention can be interpreted by the following claims only.

FIG. 1 is a conceptual diagram illustrating a concept of a PCS melt spinning process according to an embodiment of the present invention. Referring to FIG.

Referring to FIG. 1, the melt spinning process of the PCS is largely accomplished in the spinning system 100 and the conveyor belt system 200.

First, the synthesized PCS is stored in the melting chamber 110. The PCS can be synthesized using dimethylchlorosilane (DDS) as a starting material, and PCS finally synthesized through polydimethylsilane (PDMS) as an intermediate product can have various molecular weights depending on the molecular weight of the starting material and the intermediate product have. Therefore, the softening point and the melting point to be described later are temperatures that vary depending on the molecular weight of the PCS. On the other hand, metal elements such as Al, Zr, Hf, and Ti may be added to the PCS in order to compensate for physical properties at the time of synthesis or right after synthesis.

The PCS filled in the melting chamber 110 is transferred to the discharge part 130. The PCS transferred to the discharge part 130 is quantified and transferred to the discharge part 130 by the pressure of the metering pump 120.

The discharge unit 130 is provided with a filtering member 132 for filtering impurities of PCS and a nozzle unit 134 for radiating PCS. The discharge unit 130 is connected to the air pump 140. The air pump 140 supplies the heated air to the periphery of the nozzle unit 134 at a high speed so that the emitted PCS is blown and spread, So that the fibers can be radiated with a diameter smaller than that of the melt spinning.

The PCS 50 discharged from the discharge portion 130 is discharged onto the conveyor belt 120 of the conveyor belt system 200. On the conveyor belt 120, a plurality of pins 212 are uniformly arranged. The fin 212 may be made of a metal material, and the diameter of the fin 212 may be several millimeters or less. The diameter can be appropriately changed in consideration of the use of the mat-type SiC fiber to be produced and the degree of required porosity.

The discharged PCS 50 is positioned on the conveyor belt 210, and a predetermined through-hole is formed by the fin 212. On the other hand, a suction device 220 for inducing vertical adsorption of the discharged PCS 50 is disposed on the conveyor belt 210. Accordingly, the discharged PCS 50 is adhered to a certain degree in the vertical direction to have a mat shape. However, the contact force between the discharged PCS fibers is weak, and it is necessary to reinforce the fusion force between them so that they can be manufactured as a stable mat. The interfiber coalescence and adhesion for this purpose can be achieved in the stabilization step which proceeds for the incompatibility as described later. That is, according to the method of the present invention, the bonding between fibers in the mat can be realized by unifying in the stabilization step, which is an essential step, without a separate additional step. The initial mat formed on the conveyor belt 210 can be automated To the chamber for the stabilization step described below.

The stabilizing step may be of a batch type or a continuous type, but the mat type PCS fiber separated from the conveyor belt 210 for interfiber fusing to strengthen the binding force of the mat described above must pass through a specially designed temperature range.

The stabilization step is a step in which the PCS fiber is infused by being heated in an air atmosphere. Alternatively, the stabilization step may be performed by a method of curing under an inert gas and an unsaturated hydrocarbon atmosphere. In this case, the oxygen content of the produced mat-type SiC fiber can be remarkably lowered.

FIG. 2 is a temperature graph showing the temperature change in the stabilization step according to an embodiment of the present invention. FIG.

Referring to FIG. 2, the stabilization step can be completed by placing the mat type PCS fiber in a chamber or the like and passing the temperature interval as shown in FIG. First, the PCS fiber passes through a temperature interval equal to or greater than the softening point and equal to or lower than the melting point for t1 hour. The softening point is a temperature at a point where the PCS fibers are softened in a gel-like state. During the t1 time, the surface fusion bonding is performed between the PCS fibers in the mat, so that the binding force of the mat can be strengthened. However, the temperature maintained for the time t1 should not exceed the melting point. The time t1 is preferably a time of less than 5 minutes when only a few minutes are achieved. That is, it can be understood as a short temperature interval of a temperature peak level on the graph.

The softening point may vary depending on the molecular weight of the PCS and the like. In this embodiment, the softening point is a temperature within a temperature range of approximately 190 to 230 ° C. In addition, the temperature at which the melting point or viscosity is in the range of 10 Pa · s and the PCS is completely melted is also variable depending on the molecular weight of PCS, etc., and is a temperature having a value before and after about 300 ° C. in the present embodiment. Fibers - 250 to 270 ° C are suitable for fusing between surfaces of fibers.

After a temperature interval of t1 for a short period of time, the temperature is continuously lowered and the PCS fiber is infused for a period of time t2 at a temperature below the softening point. The time t2 at which the incompatibility is performed is in the range of several hours, and in the present embodiment, the incompatibility is performed for about 1 to 10 hours.

Once the stabilization step has been completed via this two-step temperature interval, the infused mat type PCS fibers can be converted to matte SiC fibers through a high temperature heat treatment step in an inert gas atmosphere. Considering that the mat type SiC fiber is utilized as a ceramic material for aradiation, the heat treatment can be performed at a temperature of about 1000 to 1600 DEG C, and even when the heat treatment is performed at a temperature of 1000 to 1200 DEG C, .

The mat type SiC fiber produced by the above method can secure sufficient shape stability and porosity, and the method according to the present invention requires a further simplified process for securing a separate shape or an additional process for ensuring porosity The mat type SiC fiber can be manufactured, and ultimately the unit cost of the material to be produced can be lowered.

Claims (6)

Synthesizing polycarbosilane (PCS);
Forming matted PCS fibers by blowing the synthesized PCS by blowing air;
The mat-type PCS fibers,
i) inducing surface fusion between the fibers in the mat type PCS fiber by heating for a time t1, at a temperature above the softening point of the PCS and below the melting point; And ii) insolubilizing said mat type PCS fiber for a time of less than t2 hours at a temperature below the softening point; And
And a heat treatment step of converting the stabilized mat type PCS fibers into matte type SiC fibers by heat treatment.
The method according to claim 1,
Wherein the t1 is less than 5 minutes.
The method according to claim 1,
Wherein the t2 is 1 to 10 hours.
The method according to claim 1,
Wherein the heat treatment step is performed at a temperature of 1000 to 1200 占 폚 in an inert gas atmosphere.
The method according to claim 1,
Wherein the PCS is radiated onto a conveyor belt on which a plurality of pins are formed.
6. The method of claim 5,
Wherein the conveyor belt comprises a suction device for closely contacting the PCS fibers spun on the conveyor belt in a direction perpendicular to the conveyor belt surface.

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