JPH07197264A - Surface treating method of fiber, reinforced fiber and its application - Google Patents

Abstract

PURPOSE:To provide a simplified CVD method capable of improving the surface property of a continuous inorganic fiber for reinforcing a ceramic matrix. CONSTITUTION:A surface treating layer of a multilayer structure composed of an under layer capable of preventing the opening of crack end and generating the withdrawal of reinforcing fiber and a surface layer having reaction resistance against the matrix is applied on the surface of the inorganic fiber 10. The different kinds of the films are continuously deposited by providing a temp. distribution in a CVD reaction furnace 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface treatment method for inorganic fibers, a reinforcing inorganic fiber subjected to the treatment, a ceramic matrix composite material using the reinforcing inorganic fiber and a method for producing the same.

[0002]

2. Description of the Related Art Ceramic matrix composite materials having high-temperature characteristics that cannot be realized by metals are being actively developed both in Japan and abroad, but materials that have excellent strength characteristics and overcome the inherent brittleness of ceramics have not yet been developed. Not appearing in the world. As a reinforcing material, powder, whiskers, short fibers,
There are long fibers, and in the case of compounding, one of these or a reinforcing material by compound reinforcement (multi-toughing) is reported (Laurel M Shepherd; Ceramic Burten [La
urel M. Sheppard, CERAMIC BULLETIN.VOL71, No.4,617-
631 (1992)]), but to date, no material system to be noted has been obtained.

It is generally known that the long fiber reinforced composite material is most effective for overcoming the toughness, but it is difficult to control the interface thereof, which is one of the causes that have not been realized to date. There is. Regarding the surface treatment of the reinforcing fiber, those relating to carbon, boron nitride, silicon carbide, etc. are disclosed, and regarding carbon, silicon carbide fibers having an amorphous carbon film formed by Ichikawa et al. Are disclosed in Japanese Patent Publication No. 1-31473.
It is disclosed in Japanese Patent No. 0. Although high-strength fiber-reinforced glass ceramics can be obtained, the ceramic matrix is not described and the reaction resistance is unconfirmed. There is also one that provides a carbon coated filament by Griffin et al. (Special Publication 5-156
No. 569 and No. 5-19406) A film is formed by a vertical furnace and a pseudo multi-layer carbon film having a different structure is exhibited due to a change in the diameter of the furnace core tube, and it is said that crack propagation and the like can be improved. ing. However, it cannot be denied that the composition is carbon alone and thus lacks in oxidation resistance. In U.S. Pat. No. 4,885,199 to Corbin et al., Weak shear properties inherent to carbon and boron nitride are used to improve properties such as toughness by utilizing interfacial bonding, but it is necessary to inhibit various interfacial property deterioration factors by only a single layer. It is difficult.

With respect to the boron nitride system, Rice disclosed in US Pat. No. 4,642,271 and suggested its effectiveness. However, the strength is low,
No clear effect was confirmed with matrices other than SiO ₂ , which showed relatively good results. Japanese Patent Publication No. 3-152270 and Japanese Patent Publication No. 4-2241
In Japanese Patent Publication No. 74, BNC having a hexagonal BN as a main structure.
x hybrid coatings or alumina overcoatings are disclosed. Although it retains high strength even at high temperatures, it is surmised that overcoating with alumina is more effective than BN. Further, Japanese Patent Publication No. 3-115140 by Sutton discloses that the original strength of the reinforcing fiber is maintained by using an inert gas as a carrier gas for obtaining the boron nitride film. However, characteristic deterioration due to the etching effect of hydrogen or the like is already known, and it cannot be said that it is very novel. In addition, regarding the crack propagation in the matrix when compounded, Carpenter et al. Have proposed compound reinforcement by various components.

A brittle fiber coating having non-filled pores for strengthening a ceramic fiber-matrix composite (Japanese Patent Publication No. 5-97528), a ductile fiber coating for strengthening a non-oxygen-based ceramic matrix composite (special Publication No. 5-85840), pre-crack fiber coating for the above purpose (Japanese Patent Publication No. 5-85).
841) and non-bonded multilayer fiber coating (Japanese Patent Publication No. 5-85842). These are all
Although it is a surface treatment method for obtaining a desired effect, an actual application example is not clear, and in Japanese Patent Publication No. 5-85842, a multilayer film is obtained by a plurality of treatment steps. It is difficult.

The present inventors have also disclosed a ceramic composite material for fiber reinforcement and a fiber for reinforcement in JP-A-3-285877, and mention the inorganic coating on the surface of the reinforcement material. In addition, a method for producing a fiber-reinforced composite material, characterized in that a preform of reinforcing fiber is impregnated with one or more containing polysilazane which is a ceramic precursor polymer, cross-linked and cured, and further fired to convert into ceramics. Although disclosed in Japanese Patent Application Laid-Open No. 4-342649, the development of a ceramic composite material excellent in high temperature characteristics has been advanced, but a further improved surface treatment method for reinforcing fibers is desired.

[0007]

[Problems to be Solved by the Invention] A surface-treated inorganic fiber which provides optimum surface treatment to a fiber for an inorganic fiber-reinforced composite material by a single CVD step, and further exhibits a new strength by a suitable surface treatment. An object of the present invention is to provide a composite material reinforced with this fiber and a manufacturing method thereof.

[0008]

In order to achieve the above object, the present invention forms two or more different temperature zones from an inlet to an outlet in one reactor having at least an inlet and an outlet. , Continuous fiber is passed from the inlet to the outlet, and two or more kinds of raw material gas are supplied into the reaction furnace,
By chemical vapor deposition of different film species in each of the above temperature zones, a surface treatment method of the fiber, characterized in that a surface treatment film of a multilayer structure is formed on the continuous fiber, the inorganic fiber surface, crack tip crack Of the reinforcing inorganic fiber, especially the surface of the inorganic fiber, which has been subjected to a surface-treating layer having a multi-layered structure including a surface layer having a resistance to the underlying layer and a matrix capable of preventing the opening of the reinforcing fiber and pulling out the reinforcing fiber. A carbon or BN layer having a graphite structure oriented in a direction perpendicular to the axis, and a reinforcing inorganic fiber characterized by having a carbon layer doped with silicon or boron on the carbon or BN layer, and the reinforcing inorganic material. Fiber-reinforced ceramic-containing matrix composite material, in particular silicon nitride ceramic-containing matrix composite material, and an aggregate of the above-mentioned reinforcing inorganic fibers Polysilazane was impregnated and baking is to provide a method for producing a silicon nitride ceramic containing matrix composites.

The present invention will be described below, but for convenience, the reinforcing inorganic fiber will be described first. The function of the reinforcement in the composite material is not manifested unless its properties are retained. It is especially important to maintain the interfacial state, and the interface of the reinforcing inorganic fibers embedded in the ceramic matrix is attacked by the chemical reaction of the constituent elements in the matrix, or shrinkage due to firing due to the thermal behavior of the matrix The physical behavior such as mismatch with the reinforcing fiber due to the coefficient of thermal expansion of is accompanied. Furthermore, when the material is used, cracks occur in the matrix due to the load applied,
This evolution behavior is reflected in the fracture morphology of the entire material. As a result, when the interface is optimum, the progress of cracks generated at the interface for the following reasons stops at the interface of the reinforcing fibers and does not lead to total destruction. (1) When the crack tip is branched along the fiber direction at the reinforcing fiber / matrix interface, energy is consumed for branching and the stress at the crack tip is relieved, so that the fracture stops. (2) If cracks propagate along the reinforcing fiber / matrix interface, extra energy is required to pull the fiber out of the matrix. In order to obtain the above effects, maintaining the interface and providing the optimum interface state are very important conditions.

The present invention is directed to solving these problems.
Inorganic fiber for reinforcement having a multi-layered surface treatment layer including a base layer capable of preventing the opening of crack tip cracks and causing withdrawal of reinforcing fiber on the surface of the inorganic fiber for reinforcement, and a surface layer having resistance to reaction with a matrix It provides a fiber by which it can have the desired properties. here,
Crack tip A layer (underlying layer) that prevents the opening of cracks and allows the reinforcing fibers to pull out has a crystal structure that patents that the crack tips of the cracks generated in the composite material are branched. , Basically, it is effective if it has a crystal structure different from that of the fiber and matrix, but more optimally it is mainly a structure in which hexagonal mesh planes are laminated and oriented in the direction perpendicular to the fiber axis direction. Structures such as carbon or boron nitride are preferred.

Further, the layer (surface layer) having resistance to reaction with the matrix means NH ₃ , H ₂ , which is a decomposition gas generated when the matrix is fired, Si-containing gas, hydrocarbon gas, especially NH _3. , H ₂ is intended to prevent the underlayer from being directly attacked, and substances such as silicon carbide, silicon nitride, boron carbide and boron nitride can be used.
However, the function of this surface layer is effective even if it does not have a perfect crystal morphology, and is several atom% relative to the underlayer.
The following contents are sufficient.

[0012] In short, the base layer has a function of preventing the opening of crack tip cracks and facilitating the pulling out of the reinforcing fibers as compared with the bare inorganic fiber, and the surface layer forms a matrix as compared with the base layer. It is a layer having an action of improving the reaction resistance of. Further, the multilayer structure here means that the composition of the layer is different between the underlayer side and the surface side of the surface treatment layer, the boundary does not necessarily have to be completely separated,
The composition may change continuously.

Illustrative of such a suitable surface treatment layer is a layer in which the surface side of a carbon or BN layer is doped with silicon or boron. The carbon or BN layer preferably has a graphite structure oriented in a direction perpendicular to the fiber axis so that the crack tip at the reinforcing fiber / matrix interface is branched along the fiber direction, consuming energy in the branch, and crack tip. Since the stress is relaxed, the opening of the crack tip crack is prevented, and the crack opening in the matrix progresses while the reinforcing fiber is held, so that the reinforcing fiber is pulled out.

On the other hand, the carbon or BN layer has a drawback that it easily reacts with the ceramic precursor polymer, especially during firing.
Doping with silicon or boron (or both) reduces reactivity with the ceramic precursor polymer. At this time, it is preferable that carbon or BN is made amorphous, and for this purpose, the doping amount of silicon or boron is 1
It is preferably 0 atom% or less, and more preferably 2 to 5 atom%. Excessive silicon or boron is not preferable because SiC crystals are formed and the elastic modulus of the fiber decreases.

The total thickness of the surface treatment layer is 30 to 5000.
Å, more preferably 100 to 1000Å. If this thickness is too small, the effect of surface treatment is not obtained, while if it is too thick, physical matching such as the elastic modulus of the reinforcing fiber / matrix interface is not good. The thickness of the surface layer (silicon or boron doped layer) in the surface treatment layer is preferably 20 to 100Å, particularly 30 to 60Å. The underlayer plays a role in causing the pull-out of the reinforcing fibers, and making the surface layer thicker than necessary undesirably reduces this effect.

Further, it is preferable that the composition between the underlayer and the surface treatment layer of the surface treatment layer continuously changes and has a concentration gradient. This is because the base layer and the surface layer are well compatible with each other and there is no fear of peeling, and the desired reaction resistance can be provided on the surface side. Oxygen may be contained as an optional component in the C or BN-based surface treatment layer, and mixing up to several atom% does not significantly change the interface property.

Here, the inorganic fiber used as the reinforcing material is an inorganic fiber containing silicon and nitrogen as essential components, and oxygen, carbon and metals as optional components, and the crystallinity is crystalline or amorphous. However, it is preferably substantially amorphous. In other words, the size of amorphous or crystallites (measured using the X-ray diffraction half-width method (JONES method)) by X-ray diffraction analysis is 2 in all directions.
Those containing a fine crystal phase of 000Å or less are preferable. A particularly preferred crystallite size is 1000 Å or less, and a more preferred crystallite size is 500 Å or less.

Note 1) HP Klug and LE Alexander, "X-
Ray DIFFRACTION PROCEDURES (2nd Edition), P618 ~ Ch
apter9 (1974), John Wiley & Sons. The proportion of the microcrystalline phase is set so that the X-ray small angle scattering intensity does not exceed 20 times that of air.

The ratio of each element constituting the particularly preferred silicon nitride inorganic fiber used in the present invention is expressed by atomic ratio, N
/ Si 0.05-3, O / Si 15 or less, C / Si
7 or less, M / Si 5 or less, and a preferable atomic ratio is N / Si 0.1 to 2.3, O / Si 10 or less,
C / Si is 3.5 or less and M / Si is 2.5 or less.
More preferable atomic ratio is N / Si 0.5 to 2.0, O
/ Si 4 or less, C / Si 3.5 or less, M / Si 1
The following is provided (however, M is one or more selected from the group of metal elements belonging to Group I to Group VIII of the Periodic Table of the Elements).

When the element ratio is not within the above range,
Tensile strength as a fiber for reinforcing ceramic composite materials,
It is not possible to exhibit the performance capable of satisfying the elastic modulus and the heat resistance. Further, according to the study of the present inventors, when the inorganic fiber as the reinforcing fiber of the ceramic composite material has a specific small angle scattering strength, it is extremely effective in achieving the above-mentioned object. It has been found.

The property required for the reinforcing fiber of the ceramic composite material is that the small angle scattering intensity is in the range of 1 to 20 times the scattering intensity of air at 1 ° and 0.5 °, respectively. A preferable small angle scattering intensity ratio is 1 to 10 times, and a more preferable intensity is in the range of 1 to 5 times for both 1 ° and 0.5 °. The small-angle scattering intensity detects the presence of fine pores inside the inorganic fiber, that is, voids or vacancies. If fine pores are present in the fiber, small-angle scattering intensity is caused by uneven distribution of electron density in the system. Is observed.

The silicon nitride-based inorganic fiber having the above-mentioned characteristics is represented by the general formula

[0023]

[Chemical 1]

It can be obtained by spinning polysilazane having a repeating unit represented by and having a number average molecular weight in the range of 100 to 500,000 and firing the spun fiber.
In the above general formula, R ¹ , R ² and R ³ are each independently a substituent or skeleton composed of a hydrogen atom, a nitrogen atom, an oxygen atom, a carbon atom, a silicon atom and a hydrocarbon group, and R ¹ , R ² and R ³ All of R ³ may be the same or different in at least one kind. Examples of the hydrocarbon group include an alkyl group, an alkenyl group, a cycloalkyl group, an aryl group and the like.

In particular, those obtained by firing perhydropolysilazane (inorganic polysilazane) in which R ¹ , R ² and R ³ in the above formula are all hydrogen atoms are preferable. Besides, similar silicon nitride fibers can be produced from various polysilazanes, and such polysilazanes are disclosed in JP-A-3-285877.

In addition to the above-mentioned fibers, other reinforcing inorganic fibers may be used in order to produce fiber-reinforced ceramic composite materials suitable for various uses and purposes. Examples of these fibers include glass fibers, carbon fibers, boron fibers, silicon carbide fibers, alumina fibers, silica-alumina fibers, boron nitride fibers, boron carbide fibers, and silicon carbide-titanium carbide fibers.

According to the present invention, there is further provided a CVD method capable of forming a surface-treated layer having a multi-layered structure of reinforcing inorganic fibers as described above by a single CVD treatment (one reaction furnace). Conventionally reported multilayer films require a plurality of steps, which is industrially difficult due to complicated process and cost. Being able to do this in a single process gives a great advantage to the process and costs.

The purpose of this is to form two or more different temperature zones or temperature distributions from the inlet to the outlet in one reactor having at least an inlet and an outlet, and to pass continuous fibers from the inlet to the outlet. A multi-layered surface-treated film is formed on the continuous fiber by spinning and feeding two or more kinds of raw material gas into the reaction furnace to cause chemical vapor deposition of two or more different film species due to the above temperature distribution. It is achieved by a fiber surface treatment method characterized by forming.

That is, this method forms two or more temperature zones in one CVD reaction furnace, forms a temperature distribution in the reaction furnace, and uses this temperature distribution to deposit different films. It is the essence. Here, the temperature band can be 3 or more, which enables more precise temperature control. However, even if the temperature band is 3 or more, it is not necessary to increase the number of deposited film types in accordance with the number of temperature bands. The point is that there are different temperature zones, and as a result, two or more film species can be deposited.

In the above reaction furnace, the raw material gas is introduced into the reaction furnace from one of the inlet side and the outlet side and exhausted from the other side, and also has ports at one or more points in the middle of the reactor. In addition, two or more ports out of the ports of the entire reaction furnace including the inlet and the outlet may be used for introduction and exhaust. In this way, by controlling the point of introduction and discharge of the source gas together with the temperature distribution, more precise,
Further, it is possible to deposit a film having a multilayer structure having a more desired distribution.

The type of film that can be deposited by this CVD method is not particularly limited, and specific examples include carbon and the following. Carbides: silicon carbide, titanium carbide, zirconium carbide, vanadium carbide, chromium carbide, tungsten carbide,
Beryllium carbide, boron carbide, and other carbides. Nitride: Silicon nitride, titanium nitride, zirconium nitride, vanadium nitride, beryllium nitride, boron nitride, aluminum nitride, and other nitrides.

Oxides: alumina, silica, magnesia, zirconia, titania, mullite, cordierite,
Yttria, borate glass, high silica glass, silicon oxynitride, sialon, and other oxides. Silicide: iron monosilicide, triboron monosilicide, hexaboron monosilicide,
Dimagnesium monosilicide, manganese monosilicide, cobalt silicide, divanadium monosilicide, and other silicides.

Borides: Chromium boride, tungsten boride, titanium boride, molybdenum boride, nickel boride, dimolybdenum boride, ditungsten boride, tetraboron carbide, diboron trioxide, and other borides. The type of source gas and reaction conditions for depositing these films are known per se.

The CVD conditions in the reaction furnace are not particularly limited, but generally the temperature is 200 to 1500 ° C., preferably 1000 ° C. or higher. The pressure atmosphere can be increased to several torr to 760 torr (atmospheric pressure) under reduced pressure. As the raw material source, a material containing a composition species capable of obtaining carbon, carbide, nitride, boride, oxide or the like can be supplied. Further, as the carrier gas, at least one of hydrogen and an inert gas such as nitrogen or argon can be selected, and if desired, it can be supplied as a mixed gas.

[0035] Here, the carbon layer wherein a preferred surface treatment layer (undercoat layer) and a silicon or boron-doped carbon layer (surface layer), a silicon compound such as SiCl _4, hydrocarbons or hydrocarbon compounds such as CH ₄ (Boiling point below 100 ° C),
N ₂ and, if necessary, H ₂ as a raw material gas from the fiber inlet side in a high temperature range of 1100 to 1300 ° C. and a low temperature range of 1000 to
When the temperature is set to 1200 ° C, the carbon layer is formed in the front part of the reaction furnace and S
A carbon layer doped with i is deposited. The Si doping amount can have a concentration gradient according to the temperature distribution. Further, a boron compound such as BCl ₃ or the like, a hydrocarbon such as CH ₄ or a hydrocarbon compound (boiling point 100 ° C. or lower),
N ₂ and, if necessary, H ₂ as a raw material gas from the fiber inlet side in a high temperature range of 1100 to 1300 ° C. and a low temperature range of 1000 to
A carbon layer doped with B can be deposited at 1200 ° C. At this time, when the continuous fiber is moved into the reaction furnace, the underlying carbon layer has a graphite structure oriented in the direction perpendicular to the fiber axis (radial direction), and the surface Si or B-doped carbon layer is in an amorphous phase. You can

Further, a boron compound such as BCl ₃ or NH
₃ or silicon compounds such as amine compound SiCl ₄ , N
_2, and H ₂ as raw material gases optionally, 1000 to 1300 ° C. The high temperature range than the fiber inlet side, a low temperature range from 900 to 12
When the temperature is 00 ° C., BN can be deposited in the front part of the reactor and BN doped with Si can be deposited in the rear part. At this time, the base BN layer can be passed through the reaction furnace to form a layer having a crystal structure oriented in the direction perpendicular to the fiber axis, and the Si-doped BN surface layer can be an amorphous phase.

By impregnating the aggregate of the reinforcing inorganic fibers produced as described above with the ceramic precursor polymer and firing it to make the matrix ceramic,
Fiber reinforced ceramics composite material can be obtained,
The reinforcing inorganic fiber of the present invention, in particular, the fiber having the two-layer structure is particularly suitable for application to a silicon nitride ceramic matrix composite material.

As the precursor of this silicon nitride ceramic matrix, one or more polysilazanes selected from the following A to P, particularly polysilazane polymers having a number average molecular weight of 200 to 3000 and a viscosity at the impregnation temperature of less than 1 Pa · s ( 1) and a number average molecular weight of 200 to 100,000 and a viscosity of 1 Pa · s or more at the impregnation temperature or one or more of solid polysilazane-based polymers (2) are mixed, and the number average molecular weight of 200 to 3000 is impregnated. Viscosity at temperature 100Pa ・ s
The polysilazane-based polymer mixture (3) prepared below is suitable.

A) The main repeating unit is-[(SiH ₂ ).
_n (NH) _r ]-(In formula, n, r is 1, 2 or 3.) The polysilazane. B) main repeating unit is - [(SiH _{2) n} (N
H) _r ]-and-[(SiH ₂ ) _m O]-(wherein n,
m and r are 1, 2 or 3. ) Is polysiloxazane.

C) Compositional formula (RSiHNH) _x [(RSi
H) _1.5 N] _1-x (wherein each R independently represents an alkyl group, an alkenyl group, a cycloalkyl group, an aryl group, an alkylsilyl group, an alkylamino group, an alkylhydrazine group or an alkoxy group, and 0 .4 <x <1
Is. ) Polyorgano (hydro) silazane represented by

D) The main repeating unit is-[(SiH ₂ ).
_n (NH) _r ]-and-[(SiR'H) _n (NR ')
_r ]-(in the formula, R ′ may be the same or different and is the same as hydrogen atom or the above R, and n and r are 1, 2 or 3). E) The main repeating unit is -SiH (N <) _2- and-
[(SiR′H) _n (NR ′) _r ]-(In the formula, R ′ may be the same or different and is the same as hydrogen atom or the above R, and n and r are 1, 2 or 3. ) Is polysilazane.

F) The polysilazane of the above A is added to (R ¹ ) ₂ NH
[In the formula, each R ¹ is independently an alkyl group, or (R
² ) ₃ N- (in the formula, each R ² is independently an alkyl group or hydrogen, but at least one is not hydrogen). ] A modified polysilazane obtained by reacting with an alkylamine, an alkylsilazane, or an alkylaminosilane represented by

G) The polysilazane of the above A is alcohol,
Modified polysilazanes obtained by reacting with organic acids, esters, ketones, aldehydes, isocyanates, amides, or mercaptans. H) A high silazane polymer having a ratio of -SiH ₂ groups to -SiH ₃ groups in one molecule of 2.5 to 8.4, which is obtained by further crosslinking and branching the polysilazane of A.

I) The main repeating unit is --Si (R ³ ) ₂
NR ³ — (wherein, R ³ is independently a hydrogen atom or the same as the above R, but at least one of R ³ is a hydrogen atom), and M (OR ⁴ ) _m
(In the formula, M is an element selected from elements of Groups 2A to 5A and 2B to 5B of the Periodic Table of Elements, and R ⁴ is independently a hydrogen atom and a carbon number of 1 to 20. Represents one alkyl group or aryl group, but at least 1
R ^{4 s} are not hydrogen atoms, and m is the atomic value of M. )
A polymetallosilazane obtained by reacting a metal alkoxide represented by:

J) The main repeating unit is-[(SiH ₂ ).
_{Polyborosilazane which is n} (NH) _r ]-(in the formula, n and r are 1, 2 or 3) and -B (N <) ₂ . K) The main repeating unit is represented by —Si (R ³ ) ₂ NR ³ — (wherein R ³ is the same as above), and a cross-linking bond is formed.

[0046]

[Chemical 2]

(In the formula, each R ⁵ is independently a hydrogen atom,
A halogen atom, an alkyl group having 1 to 20 carbon atoms, an alkenyl group, a cycloalkyl group, an aryl group, an alkoxy group, an alkylamino group, a hydroxyl group, or an amino group, and R ⁶ is a nitrogen atom among R ^5. It is a residue that is bonded to the nitrogen atom of the group having, and in the last chemical formula, at least two out of a total of six consisting of three nitrogen atoms and a boron atom are used for the bridge, and the remaining atoms are R ^Five can be combined. ).

L) The main repeating unit is --Si (R ³ ) ₂
NR ³ − (in the formula, R ³ is the same as above) and represents a cross-linking bond.

[0049]

[Chemical 3]

(In the formula, R ⁵ is the same as above, R ⁶ is a residue bonded to the nitrogen atom of the group having a nitrogen atom in R ⁵ , and in the final chemical formula, at least one of the bonds is 2 are used for the bridge, and R ⁵ can be bonded to the rest of the atoms). M) is main repeating unit - [(SiH _{2) n} (N
H) _r ]-(wherein n and r are 1, 2 or 3) and a thermosetting copolymer obtained by copolymerizing a polysilazane with a thermoplastic silicon-containing polymer.

N) The main repeating unit is-[(SiH ₂ ).
_n (NH) _r ]-(wherein n and r are 1, 2 or 3) and thermosetting obtained by copolymerizing a reaction product of a polysilazane and a metal compound with a thermoplastic silicon-containing polymer. Sex copolymer. O) A thermosetting copolymer obtained by copolymerizing the polyborosilazane described in I, J, and K with a thermoplastic silicon-containing polymer.

P) Copolymers of the above polymers. Regarding these polysilazanes themselves, Japanese Patent Application No. 4-317
It is proposed in Japanese Patent Publication No. 510. An inorganic fiber aggregate is impregnated with this polysilazane and fired to obtain a silicon nitride ceramic matrix composite material. The inorganic fiber aggregate may be for preform or prepreg. Firing conditions are generally 1000 to 1400 ° C. in an inert atmosphere. During this firing, the reinforcing inorganic fiber has a reaction-resistant layer as the outermost layer, so that the lower layer is prevented from cracking and the pull-out permissible layer is protected, and as a result, this composite material exhibits an excellent composite effect and is practically usable. An inorganic continuous fiber reinforced ceramic matrix composite material is provided.

Reference Example 1 (Production Method of Inorganic Polysilazane) After replacing the reactor with a dry nitrogen in a thermostat having a temperature of 0 ° C., 4.5 liters of dry pyridine was added and kept until the temperature became constant. Then, 505.0 g of dichlorosilane (SiH ₂ Cl ₂ ) was added with stirring to obtain a white solid adduct. The reaction mixture was cooled to 0 ° C. and 360 g of dry ammonia was bubbled in with stirring.

After completion of the reaction, dry nitrogen was blown into the reaction mixture to remove unreacted ammonia, and the mixture was filtered under pressure in a nitrogen atmosphere to obtain 4.5 liters of filtrate. To this filtrate was added 5.0 liters of dry o-xylene, the solvent was removed under reduced pressure until the amount was about 4.5 liters, 5.0 liters of dry o-xylene was added, and the mixture was distilled again under reduced pressure to 3.5 liters. The solvent was obtained. A part of the solution was separated and the solvent was removed under reduced pressure to give a colorless viscous liquid.

When the molecular weight of this viscous liquid was measured by GPC, the number average molecular weight (Mn) was 902.
The viscosity was 75 mPa · S: 25 ° C. The elemental composition (% by weight) of the polymer is Si: 64.3, N: 2
It was 6.8, O: 1.9, and C: 2.6. Reference Example 2 (Method for producing modified polysilazane) After replacing the inside of a reactor installed in a constant temperature bath at a temperature of 60 ° C. with dry nitrogen, 3.0 liters of a pyridine solution of the inorganic polysilazane obtained in Reference Example 1 was added. After keeping the charging temperature constant, ammonia gas was injected. Excess gas was discharged from the control valve to set the pressure of the reactor to 5 kg / cm ² G and the pressure was maintained for 14 hours.

After completion of the reaction, 3.5 liters of dry o-xylene was added and dry nitrogen was blown to remove unreacted ammonia. Then, the solvent was removed under reduced pressure to about 3.5 liters, and further dried. 3.5 liters of o-xylene was added and distilled again under reduced pressure to obtain a 2.5 liter solution. A part of the solution was collected, and the solvent was removed under reduced pressure to obtain white solid silazane.

When the molecular weight was measured by GPC, the number average molecular weight (Mn) was 2070. The compositional ratio of silicon and nitrogen was 1.05 by elemental analysis. Reference Example 3 (Method for producing polyborosilazane) 500 ml of a pyridine solution of the inorganic polysilazane obtained in Reference Example 1 (concentration of inorganic polysilazane: 5.10% by weight)
Was placed in a pressure-resistant reaction vessel having an internal volume of 1.5 liter, 20.0 cc (0.175 mol) of trimethylborate was added, and the reaction was carried out in a closed system at 160 ° C. for 3 hours with stirring. The pressure increased by 1.0 kg / cm ² before and after the reaction. The generated gas was hydrogen and methane as measured by gas chromatography (GC). After cooling to room temperature, 500 ml of dry φ-xylene was added, and the solvent was removed at a pressure of 3 to 5 mmHg and a temperature of 50 to 70 ° C. to obtain 54.5 g of white powder. This powder was soluble in toluene, tetrahydrofuran, chloroform and other organic solvents.

The number average molecular weight of the polymer powder is GPC.
It was 1680 when measured by. The composition is Si: 42.4%, N: 25.9%, C: 8.8.
%, O: 12.7%, B: 7.0%, and H: 3.8%. Reference Example 4 (Method for producing random copolymerized silazane) After replacing the inside of a reactor installed in a thermostat at a temperature of 0 ° C. with dry nitrogen, 900 ml of dry pyridine was added and maintained until the temperature became constant, and then stirred. While adding 57.5 g of methyldichlorosilane (CH ₃ SiH ₂ Cl ₂ ) and 50.5 g of dichlorosilane (SiH ₂ Cl ₂ ) respectively, a complex mixture was formed to obtain a white solid adduct. The reaction mixture was cooled to 0 ° C. and stirred with dry ammonia 7
Blow 2g.

After completion of the reaction, dry nitrogen was blown into the reaction mixture to remove unreacted ammonia, and the mixture was filtered under pressure in a nitrogen atmosphere to obtain 850 ml of a filtrate. When 1000 ml of dry o-xylene was added to this filtrate and the solvent was removed under reduced pressure, 3
9.2 g of colorless viscous liquid was obtained. The number average molecular weight of this viscous liquid was 630 as measured by GPC.

The elemental composition (% by weight) of the polymer is Si: 54.4, N: 23.8, O: 3.0, C: 1.
It was 2.9. Reference Example 5 (Method for producing silicon nitride fiber) A xylene solution of modified polysilazane produced by the same method as in Reference Example 2 was concentrated and adjusted to 400 poise: 23 ° C.

This solution was used with a nozzle diameter of 0.1 mm and 2 holes.
50, discharge rate 2.5m / min, dry temperature 80 ℃, dry spinning, 90m / mi on winder after applying oil
Winded at a speed of n. Then, cans were removed from four bobbins of 1000 m in diameter by using a Nelson roller at a speed of 20 m / min for 1000 filaments / strands of mixed fiber, and canning was performed in a basket. The mixed raw fiber was held in ammonia at 600 ° C. for 1 hour at a heating rate of 180 ° C./Hr.

Subsequently, the ammonia calcined fiber was wound around a bobbin and continuously calcined in nitrogen. The continuous firing was performed up to 1300 ° C. at a temperature rising rate of 20 ° C./min. The obtained silicon nitride fiber has a tensile strength of 250 kgf / mm ² and a tensile modulus of 23.
It had a stoichiometric silicon nitride composition except that it contained 2.7% tonf / mm ² of oxygen and 0.2% of carbon.

Example 1 (one surface treated silicon nitride fiber)
Preparation of direction-strengthening composite material) Tonen's silicon nitride fiber (tensile strength 25
0 kgf / mm ² , tensile elastic modulus 23 tonf / mm ² , 1K strands / strand) was surface-treated by the CVD apparatus shown in FIG.
In FIG. 1, 1 is a fiber supply unit, 2 is a de-sizing furnace, 3 is a reaction furnace, 4 is a fiber winding unit, 5, 6 and 7 are heaters, 8 is a source gas supply port, 9 is an exhaust gas outlet, and 10 is It is a silicon nitride continuous fiber.

The silicon nitride fiber 10 is placed in a nitrogen atmosphere 500.
The fiber was passed through a tubular desizing furnace 2 heated to 0 ° C. to burn off adhering substances such as a sizing agent to clean the fiber surface, and then continuously passed through a tubular reaction furnace 3. The temperature inside the reaction furnace 3 was controlled to 1200 ° C. on the inlet side, 1175 ° C. in the center, and 1150 ° C. on the outlet side using heaters 5 to 7. 500 sccm of SiCl ₄ and 500 sc of CH ₄ as source gases
CM and N ₂ were flushed with 5.6 SLM (total of 6.6 SLM). Since the tube diameter of the reactor 3 is 6.0 cm, the gas flow rate is 3.9 cm /
sec. The pressure in the reactor was 760 torr (atmospheric pressure). The threading speed was set to 2 m / min (0.5 to 3
m / min is also possible).

By this treatment, a two-layer inorganic coating film having a thickness of about 0.1 μm was obtained. The carbon film having a thickness of about 0.1 micron from the fiber surface and the Si-doped carbon film (Si / C atomic ratio 2.45%) of 100 Å or less are formed on the outermost surface by Auger electron spectroscopy. Confirmed by. As the impregnating liquid, the inorganic polysilazane of A (number average molecular weight: 902, viscosity: 75 mPa.
S: 25 ° C.) and the polyborosilazane of K (number average molecular weight: 1680, solid) in a weight ratio of 10: 1, mixed polysilazane (number average molecular weight: 980, viscosity 2)
08 mPa · S: 25 ° C.) was used.

The prepreg was produced by winding the surface-treated silicon nitride fiber yarn in which the impregnating solution was dipped in one direction on a mandrel of 100 mm square and 10 mm thickness by the filament winding method, and the volume ratio of the reinforcing fiber was 50%. It was performed by press molding until it became. Thereafter, a fired body is obtained through the following crosslinking and curing and firing steps. However, since the density is low as it is, re-impregnation of the impregnating liquid, crosslinking and curing and firing steps were repeated 8 times to obtain a fired body. The steps for obtaining a fired body are as follows.

Impregnation Step The fired product (?) Placed in a metal pressure vessel was heated at 80 ° C for 10 ^-1.
After degassing by vacuuming for 1 hour at torr, the polymer was introduced and vacuum impregnated. Next, the pressure vessel was pressurized with nitrogen gas to 5 kg / cm ² G and held for 1 hour to impregnate the polymer under pressure. Crosslinking and curing process Pressurize a pressure vessel pressurized with 5 kg / cm ² G of nitrogen at a heating rate of 1 ° C
The polymer was crosslinked and cured by keeping the temperature at 200 ° C for 1 hour / min. At this time, the pressure rose to 6.7 kg / cm ² G.

Firing Step The fired body that had been cured was taken out from the pressure vessel and fired in a nitrogen atmosphere up to 1250 ° C. (heating rate 3 ° C./min, holding for 1 hour). The fiber volume content of the fired body thus obtained was 46 vol%. From fired body to JIS-R
Bending test pieces (1 × 4 × 36 mm) according to −1601 were cut out and subjected to a three-point bending strength test. The room temperature bending strength was 82 kgf / mm ² . Further, the fracture mode was non-brittle, and fiber pull-out was noticeably observed.

When the fibers in the drawn-out portion and the matrix were analyzed in the depth direction by Auger electron spectroscopy, it was found that the drawn-out position was the interface between the surface-treated film and the matrix. In addition, since the interface was retained, no change was observed in the surface-treated film. Furthermore, when the fine structure of the interface was observed with a transmission electron microscope, it was confirmed that the interface was in a close state.

Comparative Example 1 (one surface treated silicon nitride fiber)
Preparation of direction-strengthening composite material) Tonen's silicon nitride fiber (tensile strength 25
0 kgf / mm ² , tensile elastic modulus 23 tonf / mm ² , 1K strands / strand) was surface-treated by the CVD apparatus shown in FIG.
The silicon nitride fiber was passed through a tubular desizing furnace heated to a nitrogen atmosphere of 500 ° C. to burn off deposits such as a sizing agent to clean the fiber surface, and then continuously passed through the reaction furnace 3. The temperature inside the reaction furnace 3 was 1200 ° C. as a whole. CH ₄ is 1.0 SLM and H ₂ is 5.
0 SLM (total 6.0 SLM) was flown (gas flow rate 3.5 cm /
sec). Pressure is 760 torr, threading speed is 2.0 m / min
And

By this treatment, a single-layer inorganic coating (carbon) film having a thickness of about 0.1 μm was obtained. Using the same impregnating liquid as in Example 1, preparation of prepreg as in Example 1,
The impregnation, cross-linking curing and firing steps were repeated to obtain a fired body. The fiber volume content of the fired body thus obtained was 46.
It was vol%. Bending test pieces (1 × 4 × 36 mm) according to JIS-R1601 were cut out from the fired body and subjected to a three-point bending strength test. Room temperature bending strength is 23kgf / mm ²
Met. Further, the fracture mode was rather brittle, and fiber pull-out was hardly observed. The depth direction analysis of the drawn-out fibers and the matrix was performed by Auger electron spectroscopy, and it was found that the drawn-out position was at the interface between the surface-treated film and the matrix or in the surface-treated film. It is considered that this is because the interface was not retained due to the deterioration of the surface-treated film.

Further, when the fine structure of the interface portion was observed by a transmission electron microscope, a different portion of the contrast, which was considered to have a clearance of about 50 to 100 angstroms, was observed along the fiber circumferential direction at the fiber / matrix interface. It was confirmed that the interface was not retained. Comparative Example 2 (Non-surface-treated silicon nitride fiber unidirectionally reinforced composite material)
Preparation of material) Tonen's silicon nitride fiber described in Reference Example 5 (tensile strength 25
Using 0 kgf / mm ² , tensile elastic modulus of 23 tonf / mm ² , 1K strands / strand), no surface treatment was carried out to prepare a fiber reinforced composite material.

The silicon nitride fiber was passed through a tubular furnace heated to 500 ° C. in a nitrogen atmosphere, and deposits such as a sizing agent were burned off to clean the fiber surface. After that, using the same impregnation liquid as in Example 1, the steps of producing, impregnating, crosslinking and curing the prepreg were repeated in the same manner as in Example 1 to obtain a fired body. The fiber volume content of the fired body thus obtained was 55 vol%. From fired body to JIS-R1601
Bending test piece (1 x 4 x 36 mm) according to
A three-point bending strength test was conducted. Room temperature bending strength is 15kgf
It was / mm ² . Further, the fracture morphology was brittle, and fiber pull-out was not observed.

Example 2 (Surface-treated silicon nitride fiber in one direction
Preparation of Reinforced Composite Material) Tonen Silicon Nitride Fiber (Tensile Strength 250
kgf / mm ² , tensile modulus of 23 tonf / mm ² , 1K strands / strand) was surface-treated by a CVD apparatus in the same manner as in Example 1 to obtain a two-layer inorganic coating film. As the impregnating liquid, the random copolymerized silazane described in Reference Example 4 (number average molecular weight: 756, viscosity: 55 mPa · S: 25 ° C.) and the above K were used.
Polyborosilazane (number average molecular weight: 1680, solid)
And 5: 1 in a weight ratio of mixed polysilazane (number average molecular weight: 910, viscosity: 437 mPa · S: 25 ° C.)
Was used.

Then, in the same manner as in Example 1, the steps of producing a prepreg, impregnation, crosslinking and curing, and firing were repeated to obtain a fired body. However, the firing temperature was 1350 ° C. in a nitrogen atmosphere. The fiber volume content of the fired body thus obtained was 55 vol%. From fired body to JIS-R
A bending test piece (1 × 4 × 36 mm) according to 1601 was cut out and a three-point bending strength test was performed. The room temperature bending strength was 107 kgf / mm ² . Also, 20 at 1250 ° C
The room temperature bending strength after holding for 0 hour was 83 kgf / mm ² . The fracture morphology was non-brittle and fiber pull-out was noticeably observed.

Example 3 (Surface-treated silicon carbide fiber one side)
Preparation of reinforced composite material) Silicon carbide (Si-Ti-C-O) fiber manufactured by Ube Industries, Tyranno LoxM grade (tensile strength 342 kgf / mm ² , tensile elastic modulus 19 tonf / mm ² , 0.8 K strands / strand)
Was surface-treated with a CVD apparatus in the same manner as in Example 1 to obtain a two-layer inorganic coating film.

Thereafter, the same impregnating liquid as in Example 2 was used to repeat the steps of producing a prepreg, impregnation, crosslinking and curing, and firing in the same manner as in Example 2 to obtain a fired body. The fiber volume content of the fired body thus obtained was 52 vol%. Bending test piece (1 according to JIS-R1601 from the fired body
(× 4 × 36 mm) was cut out and a three-point bending strength test was performed. The room temperature bending strength was 120 kgf / mm ² . Also,
The room temperature flexural strength after holding at 1250 ° C. for 200 hours was 65 kgf / mm ² . The fracture mode is non-brittle,
Remarkable fiber pull-out was observed.

Example 4 (Surface-treated silicon carbide fiber one side
Manufacture of direction-strengthening composite material) Silicon carbonaceous (Si—C—O) fiber made by Nippon Carbon, Nicalon NL-221 fine diameter grade (tensile strength 344 kgf /
mm ² and tensile elastic modulus of 20 tonf / mm ² , 0.5K strands / strand) were surface-treated by a CVD apparatus in the same manner as in Example 1 to obtain a two-layer inorganic coating film.

Thereafter, the same impregnating liquid as in Example 2 was used to repeat the steps of producing a prepreg, impregnation, crosslinking and curing, and firing in the same manner as in Example 2 to obtain a fired body. The fiber volume content of the fired body thus obtained was 53 vol%. Bending test piece (1 according to JIS-R1601 from the fired body
(× 4 × 36 mm) was cut out and a three-point bending strength test was performed. The room temperature bending strength was 110 kgf / mm ² . Also,
The fracture morphology was non-brittle and fiber pull-out was noticeably observed.

Comparative Example 3 (one surface treated silicon carbide fiber)
Preparation of reinforced composite material) Carbon coated silicon carbide (Si-C-O) fiber made by Nippon Carbon, Nicalon NL-607 grade (tensile strength 264 kg
A fiber-reinforced composite material was produced using f / mm ² , tensile elastic modulus of 20 tonf / mm ² , 0.5K strands / strand. The carbon-coated silicon carbide fiber was passed through a tubular furnace heated to 500 ° C. in a nitrogen atmosphere, and deposits such as a sizing agent were burned off to clean the fiber surface.

Thereafter, the same impregnating solution as in Example 2 was used to repeat the steps of producing a prepreg, impregnation, crosslinking and curing, and firing in the same manner as in Example 2 to obtain a fired body. The fiber volume content of the fired body thus obtained was 41 vol%. Bending test piece (1 according to JIS-R1601 from the fired body
(× 4 × 36 mm) was cut out and a three-point bending strength test was performed. The room temperature bending strength was 82 kgf / mm ² . Further, the fracture morphology was non-brittle, but some of the fibers were not pulled out or some were not.

[0082]

EFFECT OF THE INVENTION By appropriately treating the surface of the reinforcing continuous inorganic fiber, it is possible to obtain the optimum reinforcing (compositing) effect, and to obtain a practical composite material in which the ceramic matrix is reinforced with the continuous inorganic fiber. To be In addition, it is possible to form a multi-layered treatment film on the surface of the inorganic fiber by one-time CVD (one reaction furnace).

[Brief description of drawings]

1 shows a CVD apparatus for carrying out the method of the invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Fiber supply part 2 ... Desizing furnace 3 ... Reaction furnace 4 ... Fiber winding part 5-7 ... Heater

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[Procedure amendment]

[Submission date] March 15, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 4

[Correction method] Change

[Correction content]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 5

[Correction method] Change

[Correction content]

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0003

[Correction method] Change

[Correction content]

It is generally known that the long fiber reinforced composite material is most effective for overcoming the toughness, but it is difficult to control the interface thereof, which is one of the causes that have not been realized to date. There is. Regarding the surface treatment of the reinforcing fiber, those relating to carbon, boron nitride, silicon carbide, etc. are disclosed, and regarding carbon, silicon carbide fibers having an amorphous carbon film formed by Ichikawa et al. Are disclosed in Japanese Patent Publication No. 1-31473.
It is disclosed in Japanese Patent No. 0. Although high-strength fiber-reinforced glass ceramics can be obtained, the ceramic matrix is not described and the reaction resistance is unconfirmed. There are also provides a carbon coating filaments by Griffin et al. (Japanese Patent Publication 5-1565
No. 69 and No. 5-194062 ), a film is formed by a vertical furnace, and a pseudo multilayer carbon film having a different structure is exhibited due to a change in the diameter of a furnace core tube, and crack propagation and the like can be improved. Has been done. However, it cannot be denied that the composition is carbon alone and thus lacks in oxidation resistance. In U.S. Pat. No. 4,885,199 to Corbin et al., Weak shearing properties peculiar to carbon and boron nitride and interfacial bonding are used to improve properties such as toughness. Is difficult to inhibit.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

The present invention is directed to solving these problems.
Inorganic fiber for reinforcement having a multi-layered surface treatment layer including a base layer capable of preventing the opening of crack tip cracks and causing withdrawal of reinforcing fiber on the surface of the inorganic fiber for reinforcement, and a surface layer having resistance to reaction with a matrix It provides a fiber by which it can have the desired properties. here,
Crack tip A layer (underlying layer) that can prevent crack opening and cause reinforcement fiber pull-out has a crystal structure characterized by branching of crack tips in a crack generated in a composite material. , Basically, it is effective if it has a crystal structure different from that of the fiber and matrix, but more optimally it is mainly a structure in which hexagonal mesh planes are laminated and oriented in the direction perpendicular to the fiber axis direction. Structures such as carbon or boron nitride are preferred.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0035

[Correction method] Change

[Correction content]

[0035] Here, the carbon layer wherein a preferred surface treatment layer (undercoat layer) and a silicon or boron-doped carbon layer (surface layer), a silicon compound such as SiCl _4, hydrocarbons or hydrocarbon compounds such as CH ₄ (Boiling point below 100 ° C),
N ₂ and, if necessary, H ₂ as a raw material gas , the fiber inlet side
1100 to 1300 ° C, the outlet side is 1000 to 1200
If set to ° C (the furnace temperature may differ from the set temperature
Then , a carbon layer is deposited in the front part of the reaction furnace and a carbon layer doped with Si is deposited in the rear part. Then, depending on the temperature distribution, Si
The doping amount can have a concentration gradient. Also, B
Using a boron compound such as Cl ₃ or the like, a hydrocarbon such as CH ₄ or a hydrocarbon compound (boiling point of 100 ° C. or lower), N ₂ and, if necessary, H ₂ as a raw material gas, the high temperature range from the fiber inlet side to 11
The carbon layer doped with B can be deposited by setting the temperature to 00 to 1300 ° C. and the low temperature range to 1000 to 1200 ° C. At this time, when the continuous fiber is moved into the reaction furnace, the underlying carbon layer has a graphite structure oriented in the direction perpendicular to the fiber axis (radial direction), and the surface Si or B-doped carbon layer is in an amorphous phase. You can

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0036

[Correction method] Change

[Correction content]

Further, a boron compound such as BCl ₃ or NH
₃ or silicon compounds such as amine compound SiCl ₄ , N
_{2. If} necessary, use H ₂ as the source gas, and from the fiber inlet side
1000 to 1300 ° C , outlet side 900 to 1200 ° C
When set to , BN can be deposited at the front of the reactor and BN doped with Si at the rear. At this time, the base BN layer can be passed through the reaction furnace to form a layer having a crystal structure oriented in the direction perpendicular to the fiber axis, and the Si-doped BN surface layer can be an amorphous phase.

[Procedure Amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0067

[Correction method] Change

[Correction content]

Impregnation Step After degassing the molded body placed in a metal pressure vessel by vacuuming at 80 ° C. and 10 ⁻¹ torr for 1 hour, a polymer was introduced and vacuum impregnation was performed. Next, add 5 to the pressure vessel with nitrogen gas.
The polymer was pressure-impregnated under pressure of up to kg / cm ² G and kept for 1 hour. Crosslinking and curing process Pressurize a pressure vessel pressurized with 5 kg / cm ² G of nitrogen at a heating rate of 1 ° C.
The polymer was crosslinked and cured by keeping the temperature at 200 ° C for 1 hour / min. At this time, the pressure rose to 6.7 kg / cm ² G.

[Procedure Amendment 8]

[Document name to be amended] Statement

[Correction target item name] 0068

[Correction method] Change

[Correction content]

Baking Step The cured molded body was taken out of the pressure vessel and baked in a nitrogen atmosphere up to 1250 ° C. (heating rate 3 ° C./min, holding for 1 hour). The fiber volume content of the fired body thus obtained was 46 vol%. From fired body to JIS-R
Bending test pieces (1 × 4 × 36 mm) according to −1601 were cut out and subjected to a three-point bending strength test. The room temperature bending strength was 82 kgf / mm ² . Further, the fracture mode was non-brittle, and fiber pull-out was noticeably observed. ─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] February 23, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0035

[Correction method] Change

[Correction content]

Here, the carbon layer (underlayer) and the silicon- or boron-doped carbon layer (surface layer), which are the preferred surface treatment layers, are a silicon compound such as SiCl ₄ or a hydrocarbon or hydrocarbon compound such as CH ₄ . (Boiling point below 100 ° C),
N ₂ and, if necessary, H ₂ as a source gas, 1100 to 1300 ° C. on the fiber inlet side, and 1000 to 1200 on the outlet side.
When the temperature is set to 0 ° C. (the temperature inside the furnace may be different from the set temperature), a carbon layer is deposited in the front part of the reaction furnace and a carbon layer doped with Si is deposited in the rear part. Then, depending on the temperature distribution, Si
The doping amount can have a concentration gradient. Also, B
A boron compound such as Cl ₃ or a hydrocarbon such as CH ₄ or a hydrocarbon compound (boiling point of 100 ° C. or lower), N ₂ and, if necessary, H ₂ is used as a source gas, and the high temperature range from the fiber inlet side is 10
The carbon layer doped with B can be deposited by setting the temperature to 00 to 1400 ° C. and the low temperature range to 800 to 1200 ° C. At this time, if the continuous fiber is moved into the reaction furnace,
The underlying carbon layer has a graphite structure oriented in the direction perpendicular to the fiber axis (radial direction), and the surface Si or B-doped carbon layer can be in an amorphous phase.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0036

[Correction method] Change

[Correction content]

Further, a boron compound such as BCl ₃ or NH
₃ or silicon compounds such as amine compound SiCl ₄ , N
_2, and H ₂ as raw material gases optionally a more fiber inlet side 800 to 1300 ° C., deposition by setting the outlet side 700 to 1200 ° C., BN in the reactor front portion, a BN doped with Si at the rear Can be made. At this time, the base BN layer can be passed through the reaction furnace to form a layer having a crystal structure oriented in the direction perpendicular to the fiber axis, and the Si-doped BN surface layer can be an amorphous phase.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0037

[Correction method] Change

[Correction content]

By impregnating the aggregate of the reinforcing inorganic fibers produced as described above with the ceramic precursor polymer and firing it to make the matrix ceramic,
Fiber reinforced ceramics composite material can be obtained,
The reinforcing inorganic fiber of the present invention, especially the surface treatment of the two-layer structure
The amorphous base layer (C or BN) of the laminating film is oriented during firing.
The same effect is exhibited when the structure is changed. In particular, it is suitable for application to a silicon nitride ceramic matrix composite material.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication C04B 35/80 41/89 A C23C 16/34 D01F 9/08 Z C04B 35/80 G (72) Inventor Atsu Tezuka Nishi-tsurugaoka 1-3-1, Oi-cho, Iruma-gun, Saitama Prefecture Tonen Corporation Research Institute (72) Inventor Hiroshi Kaya 1-3-3 Nishitsurugaoka, Oi-cho, Iruma-gun, Saitama Prefecture Tonen Corporation Inside the Research Institute (72) Inventor Takeshi Isoda 1-3-1 Nishitsurugaoka, Oi-cho, Iruma-gun, Saitama Tonen Research Institute

Claims (11)

[Claims] 1. In a reactor having at least an inlet and an outlet, two or more zones or temperature distributions of different temperatures are formed from the inlet to the outlet, and continuous fibers are threaded from the inlet to the outlet. Further, two or more kinds of source gases are supplied into the reaction furnace, and two or more different film species are chemically vapor-deposited due to the above temperature distribution, thereby forming a surface-treated film having a multilayer structure on continuous fibers. A method for surface treatment of fibers, which is characterized in that 2. The method according to claim 1, wherein a concentration gradient is formed in the multilayer structure of the surface treatment film. 3. The method according to claim 1, wherein the temperature zone includes a zone in which only a part of the raw material gas is subjected to chemical vapor deposition and a zone in which all of the raw material gas is subjected to chemical vapor deposition. 4. A silicon compound, a hydrocarbon or a hydrocarbon compound and N ₂ and, if necessary, H ₂ are supplied as the raw material gas so that the temperature rises from the inlet to the outlet in the reaction furnace. 4. The method of claim 1, 2 or 3 wherein the carbon layer is first deposited on the fiber surface and the silicon-doped carbon layer is deposited thereon. 5. A boron compound, a silicon compound, ammonia or an amine compound, and N ₂ and, if necessary, H ₂ are supplied as the raw material gas so that the temperature rises from the inlet to the outlet in the reaction furnace. 4. The method according to claim 1, wherein the BN layer is first deposited on the fiber surface and the Si-doped BN layer is deposited thereon. 6. A strengthened structure in which a surface treatment layer having a multi-layered structure is provided on the surface of an inorganic fiber, which includes a base layer that prevents the opening of crack tip cracks and causes pull-out of reinforcing fibers, and a surface layer having resistance to reaction with a matrix. Inorganic fiber. 7. The reinforcing inorganic fiber according to claim 6, wherein the underlayer is a carbon layer having a graphite structure oriented in a direction perpendicular to the fiber axis, and the surface layer is a carbon layer doped with silicon or boron. . 8. The total thickness of the carbon layer and the silicon or boron doped carbon layer is 30Å to 5000Å, and the thickness of the silicon or boron doped carbon layer is 20Å to 1.
The reinforcing inorganic fiber according to claim 7, which is 00Å. 9. The reinforcing inorganic fiber according to claim 7, wherein the carbon layer doped with silicon or boron is doped with silicon or boron in an amount of 10 atom% or less and has a concentration gradient from the fiber center of the fiber cross section toward the fiber surface. 10. A composite material comprising a silicon nitride ceramics-containing matrix reinforced with the reinforcing inorganic fiber according to claim 6, 7, 8 or 9. 11. A method for producing a composite material, wherein the aggregate of reinforcing inorganic fibers according to claim 6, 7, 8 or 9 is impregnated with polysilazane and fired to obtain a silicon nitride ceramics-containing matrix composite material.