JPH01229874A - Woven and knitted cloth consisting of silicon-carbon conjugated fiber and production thereof - Google Patents

Abstract

PURPOSE:To improve physical properties such as antioxidation and mechanical strength of woven cloth by forming a silicon and/or silicon carbide coating film layer on the surface of yarn of woven and knitted cloth consisting of carbon fiber. CONSTITUTION:Woven and knitted cloth consisting of carbon fiber is maintained in vapor of silicon and/or silicon carbide, then heat-treated at 1,300-2,600 deg.C and the carbon fiber yarn is silicified to give the aimed woven and knitted cloth. For example, first Si is piled on the surface of the carbon fiber yarn and reacted with the carbon fiber yarn by the successive heat treatment to form an interfacial layer consisting of SiC between Si and C (type I). Coating films of types II, III and IV are formed by heating condition, heat-treating condition and retention time thereof. Physical properties of the woven and knitted cloth consisting of the silicon-carbon conjugated fiber thus obtained are improved and the woven and knitted cloth is useful as a reinforcing base material of composite material obtained by combining the woven and knitted cloth with ceramic (glass, etc.), metal (aluminum, etc.), etc.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a woven or knitted fabric made of a silicon-carbon composite fiber having a novel structure and a method for producing the same.

Prior art and its problems It has been attempted in the past to improve the physical properties of woven or knitted fabrics (hereinafter simply referred to as woven fabrics unless otherwise required) made of carbon fibers by coating them with silicon or silicon carbide. For example, it is possible to form a coating layer of silicon or silicon carbide on a carbon fiber fabric by CVD, PVD, thermal spraying, etc., but in this case, the coating layer is only formed on the outer surface of the fabric. No coating layer is formed on the surface of the yarn existing inside. Therefore, these methods cannot substantially improve the physical properties of carbon fiber fabrics.

Means for Solving the Problems As a result of intensive research to form a coating layer of silicon or silicon carbide even inside the carbon fiber fabric, the inventor of the present invention discovered that the carbon fiber fabric was brought into contact with the vapor of silicon or silicon carbide. In this case, a coating layer of silicon or silicon carbide is formed even on the surface of the threads existing inside the carbon fiber fabric, and as a result, the physical properties of the resulting silicon-carbon composite fiber fabric are significantly improved. I found it.

That is, the present invention provides the following silicon-carbon composite fiber fabric and method for producing the same: (1) A woven or knitted fabric made of carbon fibers is characterized by having a silicon and/or silicon carbide coating layer on the fiber surface. Silicon-carbon composite fiber woven or knitted fabric.

(2) The method for producing a silicon-carbon composite fiber woven or knitted fabric as described in item 1 above, which comprises bringing the woven or knitted fabric made of carbon fiber into contact with silicon and/or silicon carbide vapor.

(2) A silicon-carbon composite fiber woven or knitted fabric characterized in that at least a portion of the fibers of the woven or knitted fabric made of carbon fibers are converted into a silicon compound.

■ After contacting the woven or knitted fabric made of carbon fibers with silicon and/or silicon carbide vapor,
3. The method for producing a silicon-carbon composite fiber woven or knitted fabric according to item 3 above, which is heat-treated at 00°C.

The carbon fiber fabric used as the base material in the present invention is P
It may be any of AN-based, pitch-based, rayon-based, vapor-grown carbon-based, etc. Furthermore, there is no limit to the method for producing woven or knitted materials.

The invention set forth in Claim 1 of the present patent application (hereinafter referred to as Claim 1 of the present patent application)
According to the invention, a carbon fiber fabric and a substance serving as a Si source, or a carbon fiber fabric and a substance serving as a SiC source are placed in a closed container and heated under temperature conditions that generate Si vapor or SiC vapor. , by bringing the generated steam into contact with a carbon fiber fabric. As a Si source,
Si is used. The Si source is preferably used in the form of small lumps or powder with an average particle size of about 5 mm or less.

Further, the SiC source is not particularly limited as long as SiC vapor is formed, but examples thereof include a mixture of 5iC1S i 02 and a carbon material, a mixture of Si and a carbon material, and the like. The blending ratio of the Sj component and the C component as 5iC77i9 is arbitrarily selected as required and is not particularly limited. The SiC source is also preferably in the form of small lumps or powder with an average particle size of about 5 mm or less. When pitch is used as a carbon abrasive for a SiC source, it is preferable to disperse 5i02 or the like in the pitch in advance. A Si source and a SiC source may be used together. In addition, when heating the carbon fiber fabric with Si source or SIC source powder filled in the voids, Si and/or SiC are efficiently attached to each thread constituting the fabric, and Si The covering layer or SiC covering layer is formed uniformly. The temperature at the time of contact between the carbon fiber fabric and Si or SiC vapor is not particularly limited as long as SiC vapor is formed, but the type of Si source or SiC source material used, evaporation area, vapor pressure, etc. may be appropriately considered. Usually 1300~
The temperature should be within the range of about 2600°C.

The contact time may be determined depending on the desired thickness of the coating layer, the thickness of each thread constituting the woven or knitted fabric, the method of forming the woven or knitted fabric, and is not particularly limited.

The silicon-carbon composite fiber fabric of the third invention of the present application is the same as that of the first invention of the present application.
The silicon-carbon composite fiber fabric of the invention is 1300 to 2600
Manufactured by heat treatment at 9C. In this heat treatment, the reaction between the Si coating layer or the SiC coating layer and the carbon fiber yarn progresses depending on the temperature and time, and at least a portion of the carbon fiber yarn is converted into SiC. This heat treatment step does not need to be carried out completely independently of the preceding step of contacting with Si or SiC vapor, and the carbon fiber fabric that has undergone the contact step with the vapor is placed in the same closed container. You may continue heating.

This heat treatment time regulates the amount of solid phase reaction due to diffusion of Si or C in the interface layer between the surface of the carbon fiber and the coating layer. Since the thickness of this interfacial phase is determined depending on the application, the heat treatment time is not particularly limited.

There are four types of silicon-carbon composite fiber fabrics according to the present invention, shown conceptually as a 1/4 cross section of yarn in FIG. It is roughly divided into two types.

In FIG. 1, hatched portions indicate non-stoichiometric composition layers or interface layers. Note that the illustrated thickness of each layer does not necessarily indicate the actual relative thickness of the carbon fiber yarn. In addition, in the non-stoichiometric composition layer or the interface layer,
The concentration of Si decreases from the surface toward the inside.

In Type I, a Si coating layer is present on the surface of the carbon fiber yarn C, and a thin SiC layer is formed between the two layers.

In type ①, the Si layer originally formed on the surface of the carbon fiber yarn reacts with the carbon C in the center through heat treatment, and a SiC layer is formed in the center. It consists of a Si layer and an inner SiC layer.

In type ①, the SiC layer initially formed on the surface of the carbon fiber yarn reacts with the carbon C in the center through heat treatment, and SiC and carbon are formed between the SiC layer on the surface and the C layer in the center. C
A mixed layer consisting of

In type (2), the Si or SiC layer originally formed on the surface of the carbon fiber yarn reacts with carbon C in the center by heat treatment, and the entire surface becomes a SiC layer.

Effects of the Invention The silicon-carbon composite fiber fabric of the present invention has excellent oxidation resistance and mechanical strength, so it is suitable for use with ceramics (
glass, nitrides, carbides, etc.), metals (aluminum,
It is used as a reinforcing base material in composite materials obtained in combination with titanium, etc.).

EXAMPLES Hereinafter, examples will be shown to further clarify the features of the present invention.

Example I Si powder (
200 mesh) was filled into a sealed graphite container, and the temperature was raised to 1700°C at a heating rate of 8°C/min, and held at the same temperature for 20 minutes.

In the process described in Figure 1, Si is first deposited on the surface of the carbon fiber yarn, and this reacts with the carbon fiber yarn to form an interfacial layer made of SiC between the Sl and C, resulting in Type I in Figure 1. A silicon-carbon composite fiber fabric corresponding to the above was obtained.

Further, the obtained silicon-carbon composite fiber fabric was pulverized and the powder was subjected to X-ray diffraction, and the results were as shown in Table 1.

Table 1 2θ Applicable substance Relative strength 2B, 4 C100 28,4Si 30 35.6 SiC80 4L, 4 SiC20 47,3S i 5 54.6 C20 Example 2 5.0 g of pitch-based carbon fiber fabric and Si lump (average Particle size 3
mm) in a sealed graphite container, and the heating rate was 1.
The temperature was raised to 2100°C at a rate of 5°C/min and held at the same temperature for 30 minutes.

In the above process, Si is first deposited on the surface of the carbon fiber yarn, and this reacts with the carbon fiber yarn to form an interfacial layer consisting of SiC between Si and C, and then the thickness of this interfacial layer increases. It was gradually increased, and finally a silicon-carbon composite fiber fabric corresponding to type H in FIG. 1 was obtained.

Further, the obtained silicon-carbon composite fiber fabric was pulverized and the powder was subjected to X-ray diffraction, and the results were as shown in Table 2.

2θ Applicable substance Relative strength 2B, 4 Si 2035.6
SiC100 414S i C25 47,3S i 3 Example 3 3.0 g of PAN-based carbon fiber material and SiC powder (100
5.0g of mesh passing) was stored in a sealed graphite container,
The temperature was raised to 1800°C at a heating rate of 15°C/min and held at the same temperature for 30 minutes.

In the above process, SiC is first deposited on the surface of the carbon fiber yarn, and this reacts slightly with the carbon fiber yarn, resulting in Si/
An interfacial layer (S i C+C) having a non-stoichiometric composition of C was formed, and a silicon-carbon composite fiber fabric corresponding to type (2) in FIG. 1 was obtained.

Further, the obtained silicon-carbon composite fiber fabric was pulverized and the powder was subjected to X-ray diffraction, and the results were as shown in Table 3.

Table 3 2θ Applicable substance Relative strength 26.4 C100 35,6SiC80 41,4SEC20 54,6C20 Figure 2 shows the cross-sectional shape of the fiber yarn of the silicon-carbon composite fiber fabric obtained in this example. This is a micrograph (cross-sectional diameter of carbon fiber yarn: approximately 7 μm). A uniform SiC coating layer of about 0.8 μm is formed on the surface of the yarn, and the fracture surface has the same plane through the coating membrane, so there is no Si between the fiber yarn and the membrane. It is clear that there is an interfacial layer having a non-stoichiometric composition of /C.

Next, while maintaining the silicon-carbon composite fiber fabric obtained in this example at 750°C, a mixed gas of 80% N2-0220% was passed through the fabric at a flow rate of 800 ml/min to measure its oxidation resistance. The results are shown as curve A in FIG. Compared to curve B showing similar test results for an untreated carbon fiber fabric, almost no weight loss due to oxidation is observed.

In addition, the bending strength of the silicon-carbon composite fiber fabric obtained in this example was measured. The results are shown in FIG. 4 as (m). Results for untreated carbon fiber fabrics and results for carbon fiber fabrics coated with SiC by CVD method (C
It is clear that the bending strength of the product of the present invention is significantly improved compared to VD).

Example 4 5.0 g of pitch-based carbon fiber fabric (!: 15!: Si lumps (average particle size 3 mm)) was placed in a sealed graphite container, and the temperature was raised to 2100 °C at a heating rate of 15 °C/min. 3 at the same temperature
Holds time.

In the above process, Si is first deposited on the surface of the carbon fiber yarn, which reacts with the carbon fiber yarn by being held at 2100°C to form an interfacial layer consisting of SiC between Si and C. The thickness of the interfacial layer was gradually increased, and finally a silicon-carbon composite fiber fabric corresponding to type (2) in FIG. 1 was obtained in which all of the carbon fiber yarns were made of SLC.

Furthermore, the obtained silicon-carbon composite fiber fabric was pulverized and the powder was subjected to X-ray diffraction, and the results were as shown in Table 4.

Table 4 2θ Applicable substance Relative strength 35.6 S i C100 41,4 S i C25 Figure 5 is a scanning electron micrograph showing the cross-sectional shape of the fiber yarn of the silicon-carbon composite fiber fabric obtained in this example. It is. It is clear that the SiC layer is completely formed all over the inside of the yarn.

Next, while maintaining the silicon-carbon composite fiber fabric obtained in this example at 750°C, a mixed gas of 80% N2-0220% was passed through the fabric at a flow rate of 800 m1/min to measure its oxidation resistance. The results are shown as curve C in FIG. No weight loss due to oxidation is observed compared to curves showing similar test results for untreated carbon fiber fabric. In the case of the product of this example, a slight increase in weight is rather observed due to the reaction of SiC→5i02 in the surface layer.

Example 5 120g of SiO2 powder (average particle size 2Azm) was prepared in advance with pitch (softening point 87°C, Q I -0,0196) 100g
After impregnating 200 g of PAN-based carbon fiber fabric in an autoclave at a temperature of 300° C. and a pressure of 40 kg/ctJ, the temperature was increased to 1° C./min at a heating rate of 2° C./min.
The temperature was raised to 000°C, and pressure carbonization treatment was performed at an initial pressure of 40 kg/ctl.

Next, the carbonized carbon fiber fabric was placed in a sealed graphite container, heated to 2500°C at a heating rate of 15°C/min, and held at the same temperature for 30 minutes.

In the above process, SiC is first deposited on the surface of the carbon fiber yarn, which slightly reacts with the carbon fiber yarn by holding at 2500'C, forming an interfacial layer having a non-stoichiometric composition of Si/C. A silicon-carbon composite fiber fabric corresponding to type ① in FIG. 1 was obtained.

Further, the obtained silicon-carbon composite fiber fabric was pulverized and the powder was subjected to X-ray diffraction, and the results were as shown in Table 5.

Table 5 λI Applicable material Relative strength 2B, 4 C50 35,68i C100 4L, 4 Si C25 54,6C10 Example 6 28g of Si powder (passed through 200 meshes) was added to the pitch (
Softening point: 87℃, Ql-0.01%) Dispersed in 18g,
Temperature 300'C in autoclave.

After impregnating the voids of 20 g of pitch-based carbon fiber fabric under a pressure of 40 kg/ctj, the temperature was raised to 800° C. at a heating rate of 2'C/min and carbonized at an initial pressure of 40 kg/cJ.

Next, the carbonized carbon fiber fabric was placed in a sealed graphite container, heated to 1500°C at a heating rate of 20'C/min, and held at the same temperature for 2 hours.

In the above process, SiC is first deposited on the surface of the carbon fiber yarn, which reacts slightly with the carbon fiber yarn by holding at 1500°C, forming an interfacial layer having a non-stoichiometric composition of Si/C. A silicon-carbon composite fiber fabric corresponding to type ① in FIG. 1 was obtained.

Further, the obtained silicon-carbon composite fiber fabric was pulverized and the powder was subjected to X-ray diffraction, and the results were as shown in Table 6.

Table 6 2θ Applicable substance Relative strength 26.4 C100 35,6S i C60 4L, 4 S i C15 54,6C20 Example 7 5iOz powder (average particle size 5 μm) 5.0g was predispersed in 7g of novolac type phenolic resin. 4. Knitted fabric of rayon-based carbon fiber at a temperature of 150°C in an autoclave.
0g sky 1! After impregnation and hardening, the sample was placed in a sealed graphite container, heated to 1300°C at a rate of 0.3°C/min, and held at the same temperature for 15 hours.

, In the above process, SiC is first applied to the surface of the carbon fiber yarn.
is deposited, and when held at 1300°C, it slightly reacts with the carbon fiber yarn, forming an interface layer with a non-stoichiometric composition of Si/C, which corresponds to type ① in Figure 1.
A carbon composite fiber knitted fabric was obtained.

Further, the obtained silicon-carbon composite fiber knitted fabric was pulverized and the powder was subjected to X-ray diffraction, and the results were as shown in Table 7.

Table 7 2θ　　　Applicable substance　　Relative strength 26.4 C80 35,6SiC80 41,4SEC20 54,6C18

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view conceptually showing the state of siliconization of the threads of the silicon-carbon composite fiber fabric according to the present invention, roughly divided into four types, I to II. FIG. 2 and FIG. 5 are scanning electron micrographs showing the cross-sectional shape of the fibers of the silicon-carbon composite fiber fabric obtained in the example of the present invention. FIGS. 3 and 6 are graphs showing the oxidation resistance of the silicon-carbon composite fiber fabrics obtained according to the examples of the present invention. FIG. 4 shows the silicon-carbon composite fiber I obtained by the example of the present invention.
It is a graph showing the bending strength of T&S products. Figure 1 Figure 2 Figure 3 Date + hM <79y) Figure 4 Figure 6 Song Question (Intermediate) Figure 5

Claims (4)

[Claims] (1) A silicon-carbon composite fiber woven or knitted fabric characterized by having a silicon and/or silicon carbide coating layer on the fiber surface of the woven or knitted fabric made of carbon fibers. (2) Fabrics or knitted fabrics made of carbon fibers are made of silicon and/or carbon fibers.
The method for producing a silicon-carbon composite fiber woven or knitted fabric according to claim 1, wherein the fabric or knitted fabric is brought into contact with silicon carbide vapor. (3) A silicon-carbon composite fiber woven or knitted fabric, characterized in that at least a portion of the fibers of the woven or knitted fabric made of carbon fibers are converted into a silicon compound. (4) Fabrics or knitted fabrics made of carbon fiber with silicon and/or
or after contact with silicon carbide vapor, 1300-2
The method for producing a silicon-carbon composite fiber woven or knitted fabric according to claim 3, characterized in that heat treatment is performed at 600°C.