JPH01111828A - Production of short fiber molding for production of composite material - Google Patents

Abstract

PURPOSE:To produce a short fiber molding in which short fibers as the raw material for a composite material are unidirectionally oriented by forming a thin sheet from a mixture composed of the shirt fibers, high-polymer material and binder and stretching the sheet unidirectionally. CONSTITUTION:The small-diameter short fibers 2 of alumina are mixed with a high- polymer soln. 4 of polyvinyl butyral alcohol, etc., and the inorg. binder such as colloidal silica is further added to the soln. at need. The soln. is then mixed well. This mixture 6 is thinly spread and disposed on a glass plate 8 and is naturally dried to form the sheet 10 having about 1mm thickness. The sheet is taken up on a roll 12 and one end thereof is fixed to another roll 14. While the sheet is kept heated by a heater 16, the sheet is taken up by pulling a roll 14 in a manner as to part said roll from the roll 12. The sheet 10 is stretched by this tensile force and the short fibers 2 of the alumina are simultaneously unified and oriented in the pulling direction. Plural sheets of the sheets 18 formed by cutting the above-mentioned sheet to a suitable length are laminated and a laminated body 22 formed by pressing the laminated sheets in metallic molds 20 is put into a case 24 made of a stainless steel and is compressed under heating by a heater 26, by which the high-polymer soln. is burned and removed. The short fiber molding 28 is thus produced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to composite materials, and more particularly to a method for producing short fiber molded bodies used in the production of composite materials.

Problems to be Solved by Conventional Technologies and Inventions ■Reduction molding method and ■Compression molding method have been widely used as methods for producing short fiber molded bodies used in the production of composite materials. As methods for aligning in one direction, (1) detonator method, (2) electrostatic alignment method, etc. are conventionally known.

In the vacuum molding method, for example, as described in Japanese Unexamined Patent Application Publication No. 60-24.3240 filed by the same applicant as the present applicant, a dispersion in which short fibers are dispersed is passed through a filter of a predetermined shape. In this method, a short fiber molded body is formed on the surface of a filter by suctioning through a filter. However, in this method, the orientation of the short fibers is three-dimensional random or two-dimensional random, and it is difficult to orient the short fibers in one direction in particular, and there is a limit to the degree of vacuum that can be achieved. Since the wall thickness cannot be increased and the volume fraction of short fibers largely depends on the fiber dimensions, it is difficult to control the volume fraction of short fibers in a short fiber molded product. It is difficult to form a fiber molded body, and there are also problems such as poor dimensional accuracy.

The compression molding method, for example, as described in Japanese Patent Application Laid-Open No. 60-240366 filed by the same applicant as the present applicant, short fibers are compressed in a mold having a predetermined shape to obtain a predetermined shape. This is a method of forming a shaped short fiber molded body. However, even in this method, the orientation of the short fibers becomes three-dimensional random or two-dimensional random, and it is impossible to achieve unidirectional orientation, making it difficult to mold short fiber molded articles with complex shapes. There is a problem that the bulk density becomes non-uniform and the quality deteriorates.

In addition, the electrodeposition method is described in, for example, "Metal Composite Materials" (edited by Isoshi Miura, Kyoritsu Shuppan), published on April 5, 1971.
As described on pages 19 to 120, when short fibers are placed in a plating bath and electroplated, the short fibers plated on one electrode are electrodeposited and collected. It is something. However, in this method, since it is essential to plate the short fibers, the matrix is limited and it takes a long time to manufacture the composite material, resulting in poor productivity. In the case of short fibers having a long fiber length, it is difficult to completely orient the short fibers in one direction.

In addition, the electrostatic alignment method is used, for example, as described in Toyota Loom Techniques No. 15, pages 21 to 25, published in April 1987, in which short fibers are placed between electrodes to which a high voltage is applied. This method utilizes the fact that when the electric field is applied, the short fibers are polarized, resulting in an orientation force that causes the short fibers to line up in the direction of the electric field. However, even in this method, there are problems in that it is difficult to orient the short fibers completely in one direction, and it takes a very long time, resulting in extremely low productivity.

Further, JP-A-59-76840 discloses a reinforced metal characterized in that a film-like body or a sheet-like body made of an inorganic whisker and an organic polymer is adhered to a metal surface by the bonding ability of the organic polymer. A method for manufacturing a precursor molded product is described, and one example of this method is to form a mixture of inorganic whiskers and an organic polymer into a sheet shape by applying compressive stress such as extrusion, thereby achieving the orientation of the whiskers. It has been proposed to orient the material in one direction. However, according to experimental research conducted by the inventor of the present application, especially when the reinforcing fibers are short fibers other than whiskers and have a large fiber length, compressive stress cannot be applied to the mixture of the short fibers and the polymeric material. It has been observed that short fibers cannot be oriented almost completely in one direction.

Furthermore, JP-A-57-29543 and JP-A-6, 1-38
As described in Publication No. 54, a composite material using short fibers as reinforcing fibers is formed, and the composite material is subjected to processing such as rolling or extrusion, or the composite material is heated to a temperature higher than the melting point of its matrix metal. It is already known to produce a composite material in which short fibers are oriented in a predetermined direction by jetting the composite material through a nozzle and then rapidly solidifying it. However, in these methods, there is a limit to the degree of plastic deformation and plastic flow of the matrix metal, so it is not possible to completely orient short fibers in one direction, and the composite material itself is There is a problem that the shape is limited to a plate shape or a rod shape.

In view of the above-mentioned problems in the conventional methods for producing short fiber molded products, the present invention provides a short fiber molded product in which short fibers are oriented in a predetermined direction such as unidirectional orientation, and has a predetermined shape and shape. The object of the present invention is to provide a method that makes it possible to efficiently produce a short fiber molded article that has a fiber volume fraction and can be used for producing composite materials with complex shapes.

Means for Solving the Problems According to the present invention, a mixture comprising short fibers and a polymeric material is formed, and a tensile stress is applied to the mixture in a state where the polymeric material is plastically flowable. This is achieved by a method for producing a short fiber molded article for producing a composite material, which comprises applying and drawing the same, and then removing the polymeric material.

Effects and Effects of the Invention According to the method of the present invention, a mixture containing short fibers and a polymeric material is formed, and the mixture is stretched by applying tensile stress to the mixture while the polymeric material is in a plastically flowable state. Therefore, in the drawing process, the polymeric material is made to flow in the tensile direction by plastic flow, and the short fibers are moved along the flow direction by the plastically flowing polymeric material, so that they are oriented in a predetermined direction. The short fibers are oriented in any orientation state such as an intermediate orientation state between three-dimensional random and two-dimensional random, an intermediate orientation state between two-dimensional random and unidirectional orientation, and substantially completely unidirectional orientation. A short fiber molded article can be easily produced.

In this case, the polymeric material may be either a thermoplastic resin or a thermosetting resin, and the stretching method may include roll winding, spinning,
This may be done by drawing, etc., and the form of the mixture after stretching may be a film, a sheet, a fiber, a rod, a cylinder, or the like. In particular, since tensile stress is applied to the mixture, the plastic flow direction of the polymeric material can be more reliably controlled in a predetermined direction than when compressive stress is applied to the mixture, and the degree of stretching can be increased. Therefore, short fibers can be more reliably oriented in one direction than when compressive stress is applied to the mixture.

According to one particular feature of the invention, the mixture comprises an uncured inorganic binder, which binder is cured after the stretching step. According to this method, the binder is cured after the short fibers are oriented in a predetermined direction, so that the predetermined orientation state and shape are maintained even after the polymeric material is removed, so that short fibers are formed. It is possible to eliminate the need for a case or the like to maintain the orientation and shape of the short fiber molded body.

In this case, it is preferable that the step of curing the binder is performed before or simultaneously with the removal of the polymeric material.

According to another detailed feature of the invention, the mixture contains granules of the material to be the matrix. According to this method, it is possible to form a short fiber molded body and at the same time to uniformly disperse the powder of the material to be the matrix between the individual short fibers, so when the material to be the matrix is metal, In this case, the short fiber molded body is processed by hot pressing, etc., or if the material to be the matrix is ceramic, the short fiber molded body is processed by sintering, etc. It becomes possible to produce fiber-reinforced metal composite materials and fiber-reinforced ceramic composite materials without filling a matrix between individual short fibers of the body.

In addition, according to this method, it is possible to form a short fiber molded body containing powder of the material to be a matrix between individual short fibers, and in this case, the powder has the function of separating the short fibers from each other. Therefore, it is possible to form a molded body with a smaller volume fraction of short fibers than in the case where powder or granules are not included. Therefore, if a composite material is manufactured by an infiltration method such as a pressure casting method using short fiber molded bodies formed by this method, it is easier to manufacture a composite material with a smaller fiber volume percentage than in the conventional method. can do.

According to yet another detailed feature of the invention, the mixture includes granules containing elements that change the composition of the matrix. According to this method, when a composite material is manufactured by a pressure infiltration method or the like using the short fiber molded article manufactured according to the present invention, elements that change the composition of the matrix diffuse and permeate into the matrix. The composition of the matrix can be changed simultaneously with the formation of the composite material.

The short fibers used in the method of the present invention may be chopped continuous fibers as well as whiskers or discontinuous fibers.
The material may be a metal, a metalloid, a ceramic, or even an organic material as long as it does not change in quality during the process of removing the polymeric material. Further, the removal of the polymeric material may be performed by baking, sublimation, elution, etc. depending on the polymeric material used.

In addition, when the shape of the short fiber molded object to be manufactured is relatively complicated or the thickness of the short fiber molded object is relatively large, or when the short fiber molded object is unidirectionally oriented along the circumferential direction, the short fiber molding is annular. When a body is manufactured, the sheet-like mixture formed by the stretching process is subjected to processing such as punching, lamination, winding, molding, etc., and then the polymeric material is removed. It's fine.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention will be explained in detail below by way of example embodiments with reference to the accompanying figures.

Example 1 First, as shown in FIG. 1, alumina fibers ("Safil RFJ" manufactured by IC1) with an average fiber diameter of 3 μm and an average fiber length of 2IIIL were mixed with 20 νt% polyvinyl butyral (
A mixture 6 containing alumina fibers and polyvinyl butyral was formed by mixing 10 νt% of PVB) into an alcohol solution 4 and stirring the mixture.

Next, as shown in FIG. 2, the mixture 6 was spread thinly on a glass plate 8 and air-dried to form a sheet 10 with a thickness of about 11 mm, a width of 20 am, and a length of 50 cm. did.

Next, as shown in FIG. 3, the sheet 1° is wound onto a roll 12, one end of which is fixed to another roll 14, and the portion of the sheet 10 between the two rolls is heated by the heater 14. Then, the sheet 1 is rolled up by winding the sheet with the roll 14 while applying a force to the roll 14 in the direction away from the roll 12 while applying resistance to the roll 12.
A tensile stress was applied to the sheet 18 in its longitudinal direction to form a sheet 18 that was stretched to about twice its length. Next, as shown in FIG. 4, the thus stretched sheet 18 is cut into 30 x 100 +++ m along the stretching direction, 30 sheets 18' thus cut are stacked, and a fifth
As shown in the figure, the material was compressed while being heated using a mold 20, thereby forming a laminate 22 having a thickness of 1°ff111.

Next, as shown in FIG. 6, the laminate 22 is filled into a stainless steel case 24 with a rectangular cross section that is open at both ends, and is heated to about 600°C by a heater 26. The molecular material polyvinyl butyral was removed by calcination. When the thus formed short fiber molded body 28 was observed with a magnifying glass, it was found that the individual alumina fibers 2 were oriented in one direction in the longitudinal direction.
The fiber volume fraction was found to be approximately 15%.

Although not shown in the figure, in order to examine whether the fiber orientation would be maintained in a predetermined state when the short fiber molded article manufactured as described above is used for manufacturing a composite material, Preheat the short fiber molded body 28 together with the case to about 400°C, place the short fiber molded body together with the case in a mold for high pressure casting,
A molten aluminum alloy (JIS standard ACIA) at 740°C was poured into the mold, and the molten metal was pressurized to approximately 1000 kg/♂ by a plunger fitted into the mold. It was held until it solidified. A composite material portion was cut out from the thus obtained solidified body, and the cross section of the blended material portion was observed using a scanning electron microscope.
It was observed that the alumina fibers remained oriented in one direction, and no disturbance in orientation occurred at all.

Example 2 Silicon carbide whiskers with an average fiber diameter of 0.5μ and an average fiber length of 150μ (“Tokamax” manufactured by Tokai Carbon Co., Ltd.)
) was mixed at 30vt% in an aqueous solution of 15vt% polyvinyl alcohol (PVA, degree of polymerization 1600) and 3wt 9g of colloidal silica and stirred to form a mixture containing silicon carbide whiskers and polyvinyl alcohol. The mixture is then heated to about 80° C. and passed through the pores (pore size 0.15a+a+) of a spinneret into a coagulation bath (boronic acid aqueous solution) 32 using an extrusion device 30, as shown in FIG. Continuously extruded as a wire rod 33,
As a result, the wire is dehydrated and solidified and wound up on the take-up roll 38 via the rollers 34 and 36, thereby applying tensile stress to the wire in its extending direction and reducing its length by approximately 5
Fibers 40 were formed by stretching the fibers twice. Fiber 4 after spinning and drawing
0 was dried by heating to about 100°C to sufficiently remove moisture. Furthermore, the fibers were heated to 240° C. in air, and in this state, the fibers were drawn approximately twice as much.

After embedding the thus formed fibers in resin and polishing them, the fibers were observed with a scanning electron microscope and found to have a diameter of approximately 20μ, with silicon carbide whiskers unidirectionally extending in the fibers. It was observed that the silicon carbide whiskers were oriented and the volume fraction of silicon carbide whiskers was about 10%.

Next, as shown in FIG. 9, the thus formed fibers, i.e. polyvinyl fibers containing unidirectionally oriented silicon carbide whiskers, were placed in a stainless steel vibrator having an outer diameter of 70 mm in the circumferential direction to a thickness of 2IIlffl. Wrap it around the
Polyvinyl, which is a polymeric material, was removed by firing it at about 600°C.

Next, the cylindrical short fiber molded body formed around the stainless steel vibrator was cut into a width of 3 cm to form a ring-shaped short fiber molded body with an inner diameter of 70 mm, an outer diameter of 74 ml, and a width of 3 fflffl. When the short fiber molded article thus formed was observed using a scanning electron microscope, it was found that the silicon carbide whiskers were oriented in one direction along the circumferential direction.

The short fiber molded body thus formed was then preheated to about 500° C., and although not shown later, the short fiber molded body was placed in the lower mold of a piston casting machine at the position of the skirt shoulder. , 730℃ aluminum alloy (
A molten metal of JIS standard AC8A) was poured, and the molten metal was pressurized at about 1200 kg/c+12 by an upper mold fitted into the mold, and the pressurized state was maintained until the molten metal completely solidified. After the molten metal has completely solidified, the solidified body is removed from the mold,
The solidified body was subjected to T6 heat treatment, and then machined such as grinding, resulting in a diameter of 76 mm and a height of 60 f.
A flffl piston was manufactured. When this piston was cut at the part reinforced with silicon carbide whiskers and the cross section was observed using a scanning electron microscope, it was found that the silicon carbide whiskers were oriented in one direction along the circumferential direction at the skirt shoulder. It was observed that there were no parts with disordered orientation.

Example 3 One silicon nitride whisker (rsNWJ manufactured by Tateho Chemical Industry Co., Ltd.) with an average fiber diameter of 0.5μ and an average fiber length of 120μ
2wt% polyvinyl alcohol (PVA, degree of polymerization 14)
A mixture containing silicon nitride voice, polyvinyl alcohol, and colloidal silica was formed by mixing 30 vt % of 00) and 5 wt % of :+o idal silica in an aqueous solution and stirring. Then, after heating this mixture to about 80° C., the mixture was continuously extruded as a bar into a coagulation bath (boronic acid aqueous solution) through a 30IIlffl nozzle in the same manner as in Example 2 above. The material was dehydrated and coagulated, and the bar material was drawn out into the air from the coagulation bath and stretched to about three times its length, and then dried by heating to about 120° C. to sufficiently remove moisture. Thereafter, the bar was further heated in air to about 240°C and stretched to about 1.5 times its length.

Next, after polishing the bar thus formed, it was observed using a scanning electron microscope, and it was found that the silicon nitride whiskers were oriented in one direction in the stretching direction of the bar, and the volume percentage was approximately 10%. was recognized.

Next, the bar material thus formed was cut to an appropriate length and compression molded while heating into the shape of a seed part of a connecting rod for a gasoline engine. Then, the molded body was heated to about 60
Polyvinyl alcohol, which is a polymeric material, was removed by firing at 0°C, thereby forming a short fiber molded body in the shape of the seed part of a connecting rod. When this short fiber molded product was observed with a scanning electron microscope, it was found that
It was observed that the silicon nitride whiskers were oriented in one direction along the longitudinal direction of the compact. In addition, the individual silicon nitride whiskers were bonded together with silica, so that their shape and orientation could be maintained without using any means such as a case.

Next, the short fiber molded body thus formed was preheated to 600°C, placed at a predetermined position in a mold for casting connecting rods, and 740°C molten aluminum alloy (JIS standard Ac4c) was poured into the mold. The molten metal was then pressurized at a pressure of about 1200 kg/an', and the pressurized state was maintained until the molten metal completely solidified. When the seed part of the connecting rod crude material was cut and the cross section was observed using a scanning electron microscope, it was found that the silicon nitride whiskers were oriented in one direction along the connecting rod seed part. It was observed that no disorder of orientation occurred.

Example 4 Carbon fibers with an average fiber diameter of 9 μm and an average fiber length of 3 mm (rM40J manufactured by Toshi Co., Ltd.) and potassium titanate whiskers with an average fiber diameter of 0°2 μm and an average fiber length of 25 μm (“Tismo” manufactured by Otsuka Chemical Co., Ltd.) were used. DJ) and pure aluminum powder with an average particle size of 20μ, respectively, at 5vt%, 5vL%, and 25%.
A mixture of these was formed by mixing and stirring into an epoxy resin in an amount of νt%.

Next, this mixture was extruded through a die having dimensions of 50 x 10 mIIl to form a plate-like body, and the plate-like body was heated with a heater to harden the epoxy resin and stretched to about twice the length. did.

After the epoxy resin has sufficiently hardened, the sheet is cut along the stretching direction to a length of 70 mm and a width of 30 V++, three of the thus obtained sheets are laminated, and the laminate is approximately 50 mm thick.
℃ and baked, thereby removing the epoxy resin, which is a polymeric material, to a length of 7011I+1 and a width of 30 mm.
A short fiber molded body having a height of 15 mm was formed.

When the fiber orientation state of this short fiber molded article was observed using a scanning electron microscope, it was found that the carbon fibers and potassium titanate whiskers were oriented at an angle of 0 to 45'' with respect to the stretching direction. .

Next, the thus formed short fiber molded body was hot pressed at a temperature of about 600°C and a pressure of 4 ton/am' for 10 minutes to produce a plate-shaped composite material.

When the cross section of the composite material thus formed was observed using an optical microscope, it was found that the carbon fibers and potassium titanate whiskers maintained the same orientation as in the short fiber molded product, and that the carbon fibers and potassium titanate The volume percentages of potassium whiskers were found to be about 12% and about 6%, respectively.

Example 5 Alumina with an average fiber diameter of 3μ and an average fiber length of 2IIlO1
Silica fiber (manufactured by Isolite Babcock Fireproof Co., Ltd.)
A mixture of 10% and 15% by weight of pure silicon having an average particle size of 5 μm was mixed into an epoxy resin and stirred to form a mixture.

Next, this mixture is extruded through a die having dimensions of 50 x 5a++n to form a plate-shaped body, and the plate-shaped body is heated with a heater to harden the epoxy resin and stretched into a sheet approximately three times as long. did. After the epoxy resin is sufficiently cured, the sheet is stretched along the stretching direction to a length I.
ClOma+, cut to a width of 101nffl, stacked 200 sheets thus obtained, and heated the laminate to about 800°C.
The epoxy resin, which is a polymer abrasive material, was removed, and a short fiber molded article having a length of 100 mm, a width of 10 a+m, and a height of 30 Il 1111 was formed. When the fiber orientation state of this short fiber molded product was observed using a scanning electron microscope, it was found that the alumina-silica fibers were oriented almost parallel to the drawing direction, and silicon particles were present between the individual fibers. It was recognized that there was.

Next, aluminum alloy (JI) was used as the matrix metal.
Example 1 except that CI A) was used.
A composite material was manufactured using the same procedure and conditions as in the case of , and when the cross section of the composite material was observed using a scanning electron microscope, it was found that the alumina-silica fibers remained oriented in one direction. It was observed that no disorder of orientation occurred. Furthermore, when the composition of the matrix metal was analyzed by EPMA, it was found that the silicon content had changed from about 1% to about 7%1.

Example 6 Silicon carbide voice strength with an average fiber diameter of 0.5μ and an average fiber length of 150μ (“Tokamax” manufactured by Tokai Carbon Co., Ltd.)
) and powder of aluminum alloy (JIS standard 6061) with an average particle size of 40μ are mixed in an aqueous solution of 20wt% polyvinyl alcohol (PVA, degree of polymerization 1600) and 3vt% colloidal silica at 15vt% and 20vt%, respectively, and stirred. A mixture consisting of these was formed.

The mixture was then heated to about 80°C and the mixture heated to 50°C.
A plate-shaped body was formed by extrusion through a 0x5 mm nozzle, and then stretched at twice the extrusion speed in the longitudinal direction into a sheet approximately twice as long as the extrusion speed. Then about 1 sheet
Dry by heating to 00°C to remove moisture sufficiently, and stretch the sheet to a length of 100 mm and a width of 200 mm along the stretching direction.
By cutting 111 sheets, laminating 20 sheets thus obtained, filling the laminated body into a stainless steel case open at both ends, and heating each case to about 500 ° C.
The polymeric material polyvinyl alcohol was removed.

When the fibrous molded article thus formed was observed under a scanning electron microscope, it was found that the silicon carbide whiskers were oriented in one direction along the stretching direction.

Next, preheat the short fiber molded body together with the case to 400 ° C., place the short fiber molded body together with the case in a die for pressure casting,
Inside the mold, a 730℃ aluminum alloy (IIs standard 6
061) was poured, the molten metal was pressurized to about 1000 kg/an2 by a plunger fitted into the mold, and the pressurized state was maintained until the molten metal completely solidified. A section of the composite material was cut out from the thus obtained solidified body, and the cross section of the composite material section was observed using a scanning electron microscope. As a result, the silicon carbide whiskers remained oriented in one direction, indicating that the oriented It was observed that substantially no turbulence occurred, and the volume fraction of silicon carbide whiskers was a very low value of about 3%.

Example 7 Carbon fiber (rM40J manufactured by Toshi Co., Ltd.) with an average fiber diameter of 9μ and an average fiber length of 5rIII11 was added to an epoxy resin at 20V.
A mixture of carbon fiber and epoxy resin was formed by mixing t% and stirring. This mixture was then diluted with 2
It is extruded from a 300 mm x die and formed into a plate shape, and is cured by heating with a heater for about 30 minutes.
The film was stretched to double the length, thereby forming a first sheet.

In addition, by mixing 3vL% of alumina-silica fibers ("Kaowool" manufactured by Isolite Babcock Fireproof Co., Ltd.) with an average fiber diameter of 3μ and an average fiber length of 3IIffl into epoxy resin and stirring, the alumina-silica fibers and epoxy resin are combined. A mixture was formed.

Next, this mixture was formed into a plate shape in the same manner as the first sheet, and was further stretched to about 1.5 times the length to form two second sheets.

Next, place aluminum foil (JIS standard lN) on the top and bottom of the first sheet.
99), place a second sheet above and below those aluminum foils, and then place aluminum foils (JIS
The epoxy resin was removed by firing the laminate at about 550° C. to form a short fiber molded product. When this short fiber compact was observed using a scanning electron microscope, it was found that the carbon fibers were oriented almost in one direction in the drawing direction, and the alumina-silica fibers were oriented almost two-dimensionally at random. It was done.

Next, the thus formed short fiber molded body was cut into an appropriate size and hot pressed to form a composite material made of aluminum compositely reinforced with carbon fibers and alumina-silica fibers.

When the cross section of the composite material thus formed was observed using a scanning electron microscope, it was found that there was a layer reinforced with carbon fibers and a layer reinforced with alumina-silica fibers located on both sides of the layer, and the carbon fibers were reinforced with alumina-silica fibers. is oriented almost in one direction,
The alumina-silica fibers were oriented almost two-dimensionally at random, and it was observed that no disturbance in the orientation of these fibers occurred.

Although the present invention has been described in detail with respect to specific embodiments above, the present invention is not limited to these embodiments, and various other embodiments are possible within the scope of the present invention. This will be obvious to those skilled in the art.

[Brief explanation of the drawing]

Figure 1 is an illustration showing the process of forming a mixture containing alumina fibers and polyvinyl butyral, and Figure 2 is an illustration showing the process of forming the mixture formed by the process shown in Figure 1 into a sheet shape. Figure 3 is an illustration showing the process in which the sheet formed in the process shown in Figure 2 is stretched, and Figure 4 is an illustration showing the process in which the sheet formed in the process shown in Figure 3 is stretched. An illustration showing the process of laminating, FIG. 5 is an illustration showing the process of heating and compression molding the laminate formed by the process shown in FIG. 4, and FIG. An illustration showing the process in which polyvinyl butyral as a polymer material is removed by heating the molded body formed in the molding process, and Figure 7 is a diagram showing the process of removing polyvinyl butyral as a polymeric material. Fig. 8 is an illustration showing a partially broken case of a short fiber molded article containing the short fiber molded article, and Fig. 8 is an illustration showing a process in which a mixture containing silicon carbide whiskers and polyvinyl alcohol is formed into a rod shape and drawn by spinning. Figure 9 is the 8th
FIG. 2 is an illustrative diagram showing how the fibers formed by the process shown in the figures are wound around a stainless steel pipe. 2... Alumina fiber, 4... Polyvinyl butyral alcohol solution, 6... Mixture, 8... Glass plate,
10...Sheet, 12.14...Roll, 16...
·heater. 18.18'... Sheet, 20... Compression mold,
22... Compression molded body, 24... Stainless steel case. 26... Heater, 28... Short fiber molded body, 30...
- Extrusion device, 32... boronic acid aqueous solution, 33... wire, 34.36... roller, 38... winding roll, 40... fiber. 42... Stainless steel vibrator Hayabusa 8 Figure 9 Figure 30... Extrusion device 33... Wire rod 40... Fiber

Claims (4)

[Claims] (1) Forming a mixture containing short fibers and a polymeric material, applying tensile stress to the mixture to stretch it while the polymeric material is plastically flowable, and then removing the polymeric material. A method for producing a short fiber molded article for producing a composite material, including: (2) The method for producing a short fiber molded article for producing a composite material according to claim 1, wherein the mixture contains an uncured inorganic binder, and the binder is cured after the stretching step. A method for producing a short fiber molded article for producing a composite material. (3) The method for producing a short fiber molded article for producing a composite material according to claim 1 or 2, characterized in that the mixture contains powder and granules of a material to be a matrix. A method for producing a short fiber molded article for producing a composite material. (4) In the method for producing a short fiber molded article for producing a composite material according to any one of claims 1 to 3, the mixture contains powder or granules containing an element that changes the composition of the matrix. A method for producing a short fiber molded article for producing a composite material, characterized in that: