JPH0741371A - Coated fiber - Google Patents

Abstract

(57) [Summary] [Object] To provide a novel heat-resistant coated fiber and a coating method thereof. [Claim] A coated fiber comprising a ceramic or carbon fiber having a coating of a heat-resistant metal or metal-based ceramic material on its surface, said coating being substantially uniform.
It has a sufficiently high density and substantially no voids. A method of coating the ceramic or carbon fibers in a continuous tow or bundle comprises: (a) supplying a sufficient current to a metal cathode to form a plasma of atoms or ions of the cathode metal; (b) Placing the fibers in the plasma path to inflate the fibers, and (c) converging the plasma to the surface of the fibers to form a heat resistant metal or metal-based ceramic coating. Consists of.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to ceramic or carbon fibers coated with refractory metals or metal-based ceramics and methods for making the coated fibers.

[0002]

BACKGROUND OF THE INVENTION High performance fibers are increasingly being used as reinforcements in plastic, metal, ceramic and carbon matrix composites. The role of the fibers in the composite is to increase strength and modulus.
The degree of toughness achieved is largely influenced by the bond between the fibers and the matrix. When brittle reaction products are formed between the fiber and matrix, mechanical properties are often compromised.

The most sought after in these applications is related to high temperature fabrication and use at high temperatures. In such cases, the matrix is either a ceramic or metallic material. A calcination process, for example, can be used to fabricate the metal matrix composite.
High processing temperature (usually about 80 of the melting point of the matrix material)
%) And high processing pressure (usually 5-40 Kpsi, 3
In the range of 4.5 to 276 MPa), the matrix metal material is allowed to flow around the fibers to form a composite product. At these elevated temperatures, deleterious reactions between the fiber and matrix can occur. In such an ambient environment, the matrix partially chemically reacts with or dissolves the fibers. Chemical reactions are sometimes beneficial but usually result in reduced strength and toughness. In many cases, these high temperature problems can be solved by applying a barrier coating to the surface of the fiber before it is woven into the matrix.

A well known method of applying such a barrier coating to fibers is chemical vapor deposition (CVD).
For example, U.S. Pat. No. 4,343,836 (Newkr
ik et al.) discloses long woven yarns of carbon, graphite, ceramics or metals coated with at least one refractory metal selected from tantalum, niobium, molybdenum, tungsten and rhenium and made into multifilaments. . These fibers are coated by exposing the yarn to a field where the volatile halide of the coating metal reacts with hydrogen. The yarn is continuously stretched and conveyed through the coating chamber where the temperature is high enough to allow the reaction to proceed but is below about 1100 ° C. and the pressure is below about 300 Torr. The coated yarn is chilled after being separated from the gaseous reactants and gaseous reaction products.

US Pat. No. 4,581,289 (Die
terich, etc.) are a plurality of carrier fibers coated with a superconducting layer of a niobium compound represented by the general formula NbC _x N _y O _z (where x + y + z ≦ 1) selected from niobium oxycarbonitride and niobium carbonitride. Disclosed is a superconducting fiber bundle fiber composed of a carrier fiber. The superconducting layer of niobium compound has a fine grained B1 structure with an average grain size of 3 to 50 nm, 100
It is reported to have a layer thickness of ˜200 nm and a nonuniform distribution of occlusion of the insulator in the B1 structure niobium compound particle group. Fiber coatings are currentless
s wet) can be done by chemical treatment or CVD. When the fibers are coated by a physical treatment such as reactive cathodic sputtering, the transport fiber bundles are fanned out and arranged so that the fibers are substantially parallel and parallel to one plane. The carrier fiber ribbon must be separated.

German Patent Application No. 3,706,218 (Weisweiler et al.) Discloses coating a plurality of separate fiber bundles with thin surface protection and adhesion-promoting layers of silicon carbide or plasma polymers. Deposition of the surface layer is done by radio frequency cathodic spraying or radio frequency plasma polymerization. Carbon, silicon carbide, boron, steel,
Thousands of single filaments made of glass and polymer fiber materials are put together into a deposition substrate. Between coatings, the individual filaments are electrically charged and repel each other, allowing for continuous coating with increased thickness uniformity.

US Pat. Nos. 3,625,848 and 3,836,451 (Snaper) disclose a method and apparatus for cathodic arc deposition. The method is
Emitting a beam of atomic or ionic particles of source material, and each of said particles having a kinetic energy of about 10 to 100 electron volts. The particles are deposited on the surface of the substrate and coat the substrate with a thin film of source material. The beam gun is provided with an anode and a cathode and is supplied with a current large enough to cause an arc discharge between the anode and the cathode to emit the beam.

[0008]

SUMMARY OF THE INVENTION The present invention is a barrier / intermediate coating of a refractory metal or metal-based ceramic formed on the surface of a ceramic or carbon fiber, the coating being substantially uniform. And provides a coating having a micronized and substantially void-free structure. The coating is also very adherent, generally crystallized, and also stoichiometric when reactive deposition techniques are used.

The present invention further provides a continuous tow.
Or a method of coating a bundle of ceramic or carbon fibers, wherein a sufficient current is applied to a metal cathode to form a plasma of atoms or ions of the cathode material; A method of arranging in the path of plasma, and the plasma acts to expand the fiber group (b
and a method of condensing the plasma on the surface of the fibers to form a heat-resistant metal or metal-based ceramic coating.

[0010]

Fibrous materials useful in the present invention include, for example, alumina, alumina-silica, alumina-boria-silica, boron, titanium diboride, tungsten, silicon carbide, silicon nitride, nitride. Boron and In
Included are carbon and ceramic fibers such as fibers of the cone ^™ brand. Particularly preferred fibers are alpha-
Alumina fiber and alpha-boria-silica continuous fiber provided by 3M under the trade name Nextel. The fibrous material may be in the form of tows of finite length or continuous type, containing a few or many filaments of each tow. Generally, the diameter of the fibers is about 5 to 1
The thickness is in the range of 50 μm, preferably 5 to 50 μm, and most preferably 5 to 30 μm.

Refractory metals or metal-based ceramics useful in the barrier / intermediate coatings of the present invention include, for example, molybdenum, tantalum, tungsten and niobium, aluminum, yttrium, zirconium, hafnium, gadolinium, titanium, erbium and others. Rare earth metal,
And tantalum, tungsten, niobium, zirconium,
There are hafnium and titanium carbides. Preferably, the refractory metal or metal-based ceramic is about 20-5.
It is used to form a coating thickness of 00 nm, more preferably about 50 to 300 nm.

The coating on the fibrous material is carried out using the cathodic arc vapor deposition method. An apparatus useful for this type of deposition in batch processing is shown in FIG. The vacuum chamber 10 comprises a cathode 13 formed of a conductive material, by which the fibers are coated, and a confinement ring 14 surrounding the cathode 13. The current is supplied from the high current power supply 11 to cause arc discharge between the anode 12 and the cathode 13, and the plasma 13 is formed from the cathode 13. Plasma 19 is directed by magnetic solenoid 15 and is deposited on rotating fiber tow 20 supported by chuck 21. Insulation ring 17 insulates anode 12 from the fiber tow support portion of vacuum chamber 10. Optionally, the reactive gas and / or the inert gas may be supplied via the supply pipe 16.

Another apparatus useful for such deposition and capable of continuous operation is shown in FIG. Vacuum chamber 30
Is a cathode 33 formed of a conductive material, by which the fibers are coated, and a confinement ring 34 surrounding the cathode 33.
It is configured to include and. The anode 32 constitutes a part of the chamber 30. The current is supplied from the high current power supply 31 to generate arc discharge between the anode 32 and the cathode 33, and the plasma 39 is formed from the cathode 33. Plasma 39
Directed by the magnetic solenoid 35 to deposit on the continuous fiber 40. The fibers 40 are fed from a spool 41, passed through hanging rollers 42 and 43, and conveyed to a take-up spool 44. An insulating ring 37 insulates the anode 32 from the fiber tow suspension portion of the vacuum chamber 30. Optionally, the reactive gas and / or the inert gas may be supplied via the supply pipe 36.

Inert gases which can be used in the present invention include argon, krypton, xenon, helium and other gases belonging to Group 8 of the Periodic Table which are chemically inert in a plasma environment. The use of such a gas generally facilitates the development of a more stable discharge from the cathode. Argon is generally preferred due to cost and availability considerations.

Reactive gases useful in the present invention include oxygen, nitrogen, ammonia, hydrocarbons and boron containing gases such as diborane and borazine.

When the cathode conductive material is connected to a high current power supply, an arc is formed on the cathode surface. The arcs formed are extremely mobile and are small shining regions that move rapidly across the cathode surface. The high current density contained in each spot causes rapid boiling of the cathode material to form a plasma of atoms or ions of the cathode material, which deposits on the fibers. The current density of each spot reaches 10 million A / cm ² , which causes ionization of the outflow vapor.

The high activation energy and ion fluence in the cathodic arc plasma allows control of the vapor deposition texture and formation of very dense coatings. The film has a columnar structure with fine particles, and the particle diameter is preferably about 5 to 75 nm, more preferably 15 to 25 nm.
The coating is sufficiently dense, that is, there is no substantial void inside or between the columnar structures. As used herein, "substantially free of voids" refers to no more than one visible void per 0.5 μm ² area, more specifically, when observed under a transmission electron microscope at 200,000 times. Visible air gaps are typically about 5 nm or larger in size.

The activation energy and the flux of ions act to cause the fiber tows to bulge and separate the fibers from each other, resulting in a film thickness of a substantially uniform coating, ie in both the machine and cross-section directions. Of less than 80%, more preferably less than 50%, and most preferably less than 30%. In addition, the fluctuating properties of the ionic wind due to the random nature of the arc motion on the cathode cause vibration of the fiber tows, resulting in further separation of the individual fibers. The energetic ions in the plasma cause strong atom-atom bonds with interdiffusion between the coating and the fibers, so vapor deposition by the cathodic arc method results in excellent coating deposition on fibrous materials. This excellent adhesion is
This is evidenced by the fact that when the coated fiber breaks, no separation from the break occurs.

Simply introducing a reactive gas into the coating chamber enables reactive deposition of the compound onto the fibrous material using the cathodic arc method. For example, yttrium oxide deposition occurs using a yttrium cathode and a small amount of oxygen in the chamber. Therefore, the cathodic arc can be used to deposit the non-conductive material. If sufficient reactive gas is supplied to the device, the reactive precipitation of the compound is stoichiometric,
Usually crystalline.

The fiber coatings of the present invention may be used, for example, as protective films for corrosion or erosion control, as diffusion barriers, as surfactants, and for the conditioned mechanical properties of composites made from these fibers. Useful as an intermediate layer for properties.

The barrier coated fibrous material of the present invention can be used to improve the toughness of inorganic and organic matrices derived from metals, ceramics, glasses, carbons and polymers. The barrier coating may improve the wetting of the fibrous material beside the matrix and create a favorable bond between the fibrous material and the matrix, thereby further increasing the toughness of the composite, Prevents chemical reaction between the fibrous material and the matrix and prevents the fibrous material from dissolving within the matrix.

The following examples serve to explain and illustrate the invention in more detail without restricting the scope of the claims. In the examples, the coated fibers are characterized using the following method.

Transmission electron microscopy (TEM) is used to determine the crystal and grain structure of the coating and to verify the presence of voids in the coating. A flat disk-shaped Ted from Redding, California with a diameter of 0.118 inches (3 mm)
A number of short length coated fiber samples are embedded in colloidal carbon paste obtained from Pella. Next, Gat
An 600 type dual ion mill, a hole with a thin tapered edge on the fiber / carbon disk only thins a small portion of this disk. Next, Jeol 200CX
Image around the tapered edge with a transmission electron microscope and observe the coated fiber showing both the fiber and the coating.

The morphology of the coating was determined using scanning electron microscopy (SEM). Samples for SEM analysis were made depending on the material coated.

The following method was used when the fibrous material was alpha-alumina fibers, typically 8-30 μm in diameter and having a circular cross-section. 0.25 inch (0.64 cm) slice section from coated fiber tow,
A section, typically containing thousands of filaments, was cut and secured to a reference alumina SEM stub with double-sided adhesive tape. The ends of the filaments were left protruding from the edges of the stub. A 0.0625 inch (0.16 cm) slice was cut from the end of the overhanging tow using scissors. The stub with filament was covered with 90 Å of gold-palladium and inserted into the SEM device. In order to image the end face of the fiber and the formed film, JEOL Co., Ltd., Tokyo, Japan is used.
SM-35C SEM or Cam, Cambridge, UK
Bridge Instruments 240 type S
EM was used.

Another SEM technique was used for carbon fibers or Nextel 480 having a diameter of 5 to 12 μm. A 0.25-inch (1.27 cm) long section slice cut from a multifilament coated tow
Diameter 1 inch (2.54 cm) Length 0.5 inch (1.
27 cm) stub, Lake Bluf, Illinois
f using Buehler's Epo-Kick epoxy. The surface of the stub in which the end of the filament is embedded in this way is
Even the diamond abrasive of m was used for polishing. Next, an M from Technics of Dublin, CA
Etching was performed at 350 watts for 15 minutes using an ICRO-RIE type barrel type oxygen plasma etching device. The stub thus produced was then covered with 90 Å of gold-palladium and observed.

X-ray diffraction was used to determine the crystalline phase of the coating. A large number of cut pieces of the coated fiber were made and these were crushed with a boron carbide mortar and pestle. The film-coated fibers crushed in this way have a diameter of 0.25 m.
m, and the wall thickness was 0.002 mm. The filled capillaries were mounted on a Debey-Scherrer powder camera manufactured by General Electric Co.
40k E-type 3 type X-ray radiation source
Copper K- from this source, operating at V and 20 mA
The diffracted x-ray pattern was imaged on photographic film with exposure to alpha x-rays for 1 hour. It was The position of the diffraction line was measured using a vernier scale, and the lattice constant and the phase were determined by comparison with the published powder X-ray diffraction pattern.

Optical microscopy (OM) was used to qualitatively determine the film quality of the transparent fibers. When the coated fiber is immersed in oil whose optical refractive index is matched with that of the sample fiber, and the fiber in the oil is observed with an optical microscope at a magnification of 1100 using interference polarization, the fiber wrapped in the film becomes almost invisible and the film is It emerges as two parallel lines. Using this technique, the uniformity of the coating along the length of the fiber can be observed. With this technique, the fibers are invisible, but the unmatched refractive index coating is clearly visible as two bright lines. From the observation of the line width, the uniformity of the coating in the direction along the fiber can be determined.

[0029]

EXAMPLES For Examples 1-8, alpha-alumina fibers were made as follows. At reflux, acetic acid-
Dissolve aluminum powder in formic acid solution
(OH _1.8 (O ₂ CCH ₃ ) _0.6 (O ₂ CH ₃ ) _0.6 of alumina formoacetate was prepared. 1000 mL
In a round bottom flask, deionized water 516.8 g, glacial acetic acid 4
4.6 mL and 33.1 mL concentrated formic acid were charged. The solution was made into a rolling boil state, and 34.9 g of aluminum metal powder was added to the boiling carboxylic acid mixture solution.
Parts, about 12 g each were added over 2 hours. An exothermic reaction occurred after the first addition, but room temperature deionized water was occasionally added to slow the reaction rate. The addition was carried out over 10 hours, the somewhat hazy solution was cooled and filtered through Whatman # 54 and Whatman # 5 filter paper. The solid phase percentage determined by gravimetric analysis was 9.25%.

Fe (NO ₃ ) ₃ was added to 800 mL of deionized water.
An iron nitrate solution was prepared by dissolving 19.73 g of 9H ₂ O. Next, 9.40 g of NH ₄ HCO ₃ was dissolved in 150 g of water, and the NH ₃ HCO ₃ solution was rapidly stirred while
₄ HCO ₃ solution was added slowly over 5 minutes. The solution was stirred and heated (maximum temperature 80 ° C.), and deionized water was flowed through a dialysis tube immersed in the solution of the iron thus hydrolyzed to perform dialysis. Heating was stopped after 40 minutes, but dialysis was performed overnight. Final diffusion is equivalent to 0.39% by weight (equ
It was iron.

Aluminum Formo Acetate Solution 1
While rapidly stirring 62 g, 13.3 g of the hydrolyzed iron polymer was added thereto to prepare a sol for spinning. To this was further added 2.5 g of 85% lactic acid solution. While continuing rapid stirring, colloidal silica of trade name Nalco2326 (particle size 50 Å, ammonium ion stabilized, 14.5% SiO ₂ , Nalco Ch
0.52 g (manufactured by electronic company) was added. Finally, water 2
And added dropwise 0g the _{Mg (NO 3) 2 · 6H} 2 O was dissolved 0.09g solution, the nominal oxide on the polymer Al ₂
O ₃ + 0.35% equivalent iron + 0.5% SiO ₂ + 0.1%
MgO was obtained.

The fibers were spun, bundled and heated in air at a heating rate of 150 ° C./min to 650 ° C. The preheated fiber is then placed in a rapid heating furnace under the trade name CM (manufactured by CM Co., Bloomfield, NJ) and rapidly heated to 1400 ° C. in air.
Maintaining this temperature for 0 minutes, the fiber was changed to alpha-alumina.

Example 1 An alpha-alumina fiber tow, 4 inches (10.2 cm) long, containing about 5000 fibers, each of said fibers having a diameter of about 16 to 30 μm, was clamped at 45 RPM. , Fixed without tension. Perkin
It is manufactured by Elmer in the Metco Cat Arc division and is shown in FIG. 1 and is US Pat.
No. 51 (Snapper), which is of the same type as that of the apparatus described by Gilmore et al., "Pulsed Meta".
llic-Plasma Generators ", P
roseceing of the IEEE. , Fifth
Vol. 8, No. 7, pages 977-991, having the magnetic solenoids and placing the clamps in a 1000 type boron nitride encapsulated cathodic arc apparatus, which is incorporated herein by reference. The fiber tow was then at a distance of 10 inches (25.4 cm) from the cathode.
2.25 inch (5.7 cm) diameter and 1 inch (2.54 cm) thick Res from Phoenix, Arizona
An yttrium cathode manufactured by each of the Earl Chemicals was placed on a water-cooled cathode support, the support was placed in a vacuum chamber of the apparatus, and the vacuum chamber was evacuated by a cryopump. After evacuating the vacuum chamber to 2 × 10 ⁻⁶ Torr, the high vacuum pump was throttled to introduce a mixed gas of argon with a flow rate of 15 sccm and oxygen with a flow rate of 55 sccm into the chamber. The chamber pressure was 11.6 mTorr. Arc discharge was started on the cathode surface and the voltage was adjusted to 150 A at 50V. 6 inches (15.2 cm) creating a 50 Gauss magnetic field
A long solenoid was activated to direct yttrium plasma to the fiber tow. During plasma adsorption, it was possible to observe that the fiber tows bulged and separated so that each individual fiber could be coated. The total adsorption time from the start of arc discharge to the extinction of arc was 5 minutes.

FIG. 3 is an SEM micrograph of this fiber showing that the coating has a fine columnar structure and a substantially uniform thickness. In a more detailed survey by SEM,
All fibers in the tow have a thickness of 150 nm and a deviation of 50
It was found that the coating could be carried out to nm.

FIG. 4 shows the T of this alpha-alumina fiber.
It is an EM micrograph showing that the coating is a fine columnar, microstructured yttrium oxide coating with no voids. It was observed that the columnar structure had a width of 15 nm and was firmly filled without any voids.

According to OM, it was found that the fibers were uniformly coated along the length direction with a film thickness of 150 nm and a deviation of 50 nm.

XRD analysis of the fiber revealed that the single phase present in the coating was yttrium oxide cubic.

Comparative Example 1 Yttrium oxide was adsorbed on the same alpha-alumina fiber surface as in Example 1 using the radio frequency (RF) sputtering method. Milwaukee, Wisconsin
A Cerac 99.9% yttrium oxide cathode having a diameter of 4 inches (10.2 cm) was placed on a cryopump type Perkin Elmer Randex sputtering system. RF power of 13.56 MHz 500 W was applied to the cathode in an atmosphere consisting of Linde UPH Specialty with a mixture of argon and 10% oxygen gas, and the chamber pressure was kept at 10 mtorr. The fibers were placed parallel to each other on a small metal frame, placed 7.5 cm from the cathode surface, and sputtered for 150 minutes. Next, the chamber was opened and the frame was rotated 180 ° with respect to the cathode. The chamber conditions were adjusted as before and sputtering was continued for 130 minutes.

The TEM micrograph of FIG. 5 shows a coarse microstructure of yttrium oxide particles, the size of the particles being 500 Å and 5 nm or more between the particles distributed throughout the film structure. It indicates that there are many voids of a size.

According to XRD analysis, the fiber coating was a mixture of amorphous and cubic crystalline yttrium oxide.

EXAMPLE 2 Using the cathodic arc system shown in FIG. 2, S. Minnesota
t. A continuous fiber tow containing 780 filaments of Paul's 3M brand Nextel ^™ 480 was coated. Phoenix, Houston, Texas
Plasma was generated in the same manner as in Example 1 except that the zirconium cathode manufactured by Metallurgical was used to generate steam, and the arc current was 150 A and the argon gas flow rate was 3
The flow rate was 7 sccm, the oxygen gas flow rate was 44 sccm, and the chamber voltage was 30 mtorr. The tow was wrapped around a suspension roller. Each roller has a diameter of 1 inch (2.54c).
m) and spaced 8 inches (20.3 cm) apart. The tow thus obtained was passed through the ionized steam seven times, and the average residence time in the steam was set to 0.5 minutes. During the plasma adsorption, it was observed that the tows of the fibers bulged and separated, and the individual fibers were covered.

OM showed that the fibers were uniformly coated in the length direction. SEM analysis of the fibers showed that all fibers in the tow had a thickness of 150 nm with a deviation of 70 nm.
It was found that the film was covered with a fine structure having a fine columnar structure having a size of nm and no void between the structures. The fine columnar shape means a columnar shape having a diameter of 150 to 200 angstrom. The SEM micrograph of FIG. 6 is
It shows a dense, uniform zirconium oxide coating on the fiber surface. The irregular image at the bottom of the fiber is considered to be an artifact of stub work.

Example 3 Arc current 150 A, Argon gas current 40 sccm,
Similar to the process described in Example 2, except that the oxygen gas flow rate was 44 sccm, the chamber voltage was 24 mTorr, and the coating time was 1 minute, the brand name Nextel ^™ 480 fiber was coated with zirconium oxide.

It was found by OM that the fibers were uniformly coated in the length direction. The SEM micrograph of FIG. 7 shows that the fibers are coated with a film having a thickness of 100 nm (deviation of 50 nm) and having a fine structure composed of a fine columnar structure with no voids between the tissues. More detailed SE
M analysis showed that all fibers in the tow were coated similarly to the fibers shown in FIG. TEM confirmed the presence of a high density and uniform zirconium oxide film on the fiber surface.

Example 4 Instead of the zirconium cathode, Phoenix Metal
Using a commercial-grade hafnium cathode manufactured by Lurgical, an argon gas flow rate of 43 sccm and an oxygen gas flow rate of 45 sccc
m, chamber pressure 28 mTorr, coating time 1 min, except that the coating time was set to 1 minute, coated with Nextel ^™ 480 fiber under the trade name Nextel ^™ 480 fibers to form a high density coating of HfO _2. Formed on Nextel ^™ 480 fiber surface.

OM revealed that the fibers were uniformly coated in the length direction. SEM analysis of the fibers showed that all fibers in the tow had a thickness of 100 nm (deviation 5
It was found to be covered with a microstructure of a fine columnar structure having no void between the tissues.

Example 5 Industria, Northbrook, Illinois
l Titanium company's titanium cathode having a purity of 99.9% was used in place of the zirconium cathode, and the arc current was 1
Example 2 except at 50 A, no argon gas was used, nitrogen was used as the reaction gas instead of oxygen, the chamber pressure was set to 11 mtorr and the coating time was 1 minute.
In the same manner as the process described above, the trade name Nextel ^™ 48
0 fiber was coated to form a TiN film on the surface of the fiber.

As can be seen from the TEM micrograph of FIG.
The fibers had a microstructured titanium nitride coating consisting of a fine columnar structure, completely void-free. Columnar structure has a width of 1
It had a thickness of 50 nm and was densely packed without voids. SEM analysis of the fibers revealed that all the fibers in the tow were coated with a fine columnar microstructure with a thickness of 300 nm (deviation 150 nm) with no voids between the tissues. According to XRD analysis of the fiber, the coating had a cubic crystal structure.

Comparative Example 5A A CVD method was used to coat the trade name Nextel ^™ 480 fiber as follows. Nextel 480 fibers were drawn from a 12 inch (30.5 cm) long tube furnace at 500 ° C. As a reactant in the furnace, hydrogen carrier gas 3
Along with 200 sccm, 32 cm of titanium tetrachloride and 1200 sccm of nitrogen were introduced.

As can be seen from the TEM micrograph of FIG. 9, the fiber had an equiaxed structure including a large number of voids having a size of 5 nm or more between the acicular particles. The SEM micrograph of the fiber showed that the coating had a void rich and fluffy microstructure. According to XRD analysis of the fiber, the coating was tetragonal titanium nitride.

Example 6 An aluminum cathode having a purity of 99.9% was used in place of the zirconium cathode, and the arc current was 50 A, the argon gas flow rate was 2 sccm, the oxygen gas flow rate was 30 sccm, the chamber pressure was 10 mTorr, and the coating time was 2 minutes. The product name Nexte is similar to the process described in Example 2 except that
l ^™ 480 fiber was coated to form a dense Al ₂ O ₃ coating on the fiber surface.

It was found by OM that the fibers were uniformly coated in the length direction. SEM analysis of the fibers revealed that all of the fibers in the tow were 100 nm thick (50 nm deviation) and covered with a fine columnar microstructure with no voids between the tissues.

Example 7 An aluminum cathode having a purity of 99.9% was used in place of the yttrium cathode, an arc current of 50 A, an argon gas current of 2 sccm, an oxygen gas flow rate of 30.1 sccm, a chamber pressure of 7.4 mTorr and a coating time of 4 minutes. Except that the length was set to 10.
Carbon fiber with a diameter of 2 cm and a diameter of 7 μm (trade name:
3K ^TM T300, Greenenv, South Carolina
ile's Amoco Performance Pro
Ducts) to form a high density Al ₂ O ₃ film on the surface of the carbon fiber.

SEM analysis of the fibers revealed that all the fibers in the tow were 200 nm thick (deviation 100 nm) and covered with a fine columnar microstructure with no voids between the tissues. .

Example 8 Purity 99.9 manufactured by Research Chemicals
% Gadolinium cathode, arc current 50 A, argon gas current 2 sccm, oxygen gas flow rate 30.1 sc
cm, chamber pressure of 11 mTorr and coating time of 2 minutes, similar to the process described in Example 1, coated with aluminum fibers of the same type as used in Example 1 to give a high density. A film of cubic gadolinium oxide was formed on the aluminum fiber surface.

SEM analysis of the fibers revealed that all the fibers in the tow were coated with a fine columnar microstructure with a thickness of 500 nm (deviation 200 nm) and no voids between the tissues. . XRD analysis of the fiber revealed a film of cubic gadolinium oxide.

Example 9 Rhoenix Metallurgical Commercial Grade Zirconium Cathode, Arc Current 150 A, No Argon Gas Supply, Flow Rate 58. Instead of Oxygen as Reaction Gas.
Example 2 except that methane was used at 5 seem and chamber pressure was set to 16 mTorr and coating time was 2 minutes.
In the same manner as the process described above, the trade name Nextel ^™ 48
A ZrC film was formed on the fiber surface.

SEM analysis of the fibers revealed that all the fibers in the tow were 100 nm thick (50 nm deviation) and covered with a fine columnar microstructure with no voids between the tissues. . XRD analysis of the fibers revealed that the coating was a zirconium carbide coating.

Example 10 As Example 2 except that a 99.9% molybdenum cathode was used, an argon gas flow rate of 15 sccm, no reaction gas supply to the chamber, chamber pressure of 10 mTorr and coating time of 2 minutes. Similarly, trade name Nextel ^TM
A high-density Mo film was formed on 480 fibers.

SEM analysis of the fibers revealed that all of the fibers in the tow were 100 nm thick (50 nm deviation) and covered with a fine columnar microstructure with no voids between the tissues. .

Example 11 Using a 99.9% molybdenum cathode, an arc current of 150
A, carbon gas flow rate 15 sccm, no oxygen supply, chamber pressure 9.8 mTorr and coating time 4 minutes were used and the same steps as in Example 1 were used to prepare carbon fiber (Thornel 3K T300 type). To form a high-density Mo film on the surface of the carbon fiber.

As can be seen from the SEM micrograph of FIG. 10, the coating had a fine columnar microstructure with no voids between the microstructures. Further detailed SEM analysis shows that all fibers in the tow have a thickness of 100 nm (deviation 50 nm)
It was found that it was covered with the film.

Example 12 Using a 99.9% tantalum cathode, an arc current of 150
A, Argon gas flow rate 15 sccm, no oxygen supply, chamber pressure 9.8 mTorr and coating time 2 minutes, except that it was set as in Example 2 under the trade name Next.
A high density Ta coating was formed on el ^™ 480 fibers.

SEM analysis of the fibers revealed that all fibers in the tow were 100 nm thick (deviation 50 nm) and covered with a fine columnar microstructure with no voids between the tissues. .

Example 13 Using a tantalum cathode having a purity of 99.9% and an arc current of 1
Carbon fiber (trade name: THRONEL ^™ 3K T300 type) was used in the same manner as in Example 1 except that the setting was 50 A, an argon gas flow rate of 15.1 sccm, no oxygen supply, a chamber pressure of 9.8 mTorr and a coating time of 4 minutes. To form a high-density Ta film on the surface of the carbon fiber.

SEM analysis of the fibers revealed that all the fibers in the tow were 100 nm thick (50 nm deviation) and covered with a fine columnar microstructure with no voids between the tissues. .

[Brief description of drawings]

1 is a side cross-sectional view of a device suitable for use with the present invention.

FIG. 2 is another side sectional view of a device suitable for use with the present invention.

FIG. 3 is a scanning electron micrograph at 12,000 times of the coated fiber of the present invention.

4 is a 100,000 × transmission electron micrograph of the coated fiber of FIG.

FIG. 5 is a 50,000 × transmission electron micrograph of a prior art coated fiber formed by radio frequency sputtering.

FIG. 6 is a scanning electron micrograph of the coated fiber of the present invention at a magnification of 6,000.

FIG. 7 is a scanning electron micrograph (7,500 ×) of the coated fiber of the present invention.

FIG. 8 is a 100,000 × transmission electron micrograph of a coated fiber of the present invention.

FIG. 9 is a 50,000 × transmission electron micrograph of a prior art coated fiber formed by chemical vapor deposition.

FIG. 10 is a scanning electron micrograph (25,300 ×) of the coated fiber of the present invention.

[Explanation of symbols]

 10, 30 Vacuum chamber 11, 31 High current power supply 12, 32 Anode 13, 33 Cathode 14, 34 Confinement ring 15, 35 Magnetic solenoid 16, 36 Supply pipe 17, 37 Insulation ring 19, 39 Plasma 20 Fiber tow 21 Chuck 40 Continuous fiber 41,44 Spool 42,43 Suspension roller

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Claims (21)

[Claims] 1. A coated fiber comprising a ceramic, carbon or metal fiber having a heat-resistant metal or metal-based ceramic material coating on its surface, said coating being substantially uniform and finely divided into fine particles. A coated fiber having a substantially void-free form. 2. The metal fiber is tungsten or Inc.
The coated fiber according to claim 1, which is oneel (trade name). 3. The coated fiber according to claim 1, wherein the fiber is alumina, alumina-silica, alumina-boria-silica, boron, titanium diboride, silicon carbide, silicon nitride or boron nitride. 4. The coated fiber of claim 3, wherein the fiber is alpha-alumina or alumina-boria-silica. 5. The coated fiber of claim 1, wherein the fiber has a diameter of about 5 to 150 μm. 6. The coated fiber of claim 1, wherein the fiber has a diameter of about 5 to 50 μm. 7. The coated fiber according to claim 1, wherein the film is molybdenum, tantalum, tungsten, or niobium; an oxide of aluminum, titanium, zirconium, hafnium, yttrium, gadolinium, erbium, or a rare earth metal; or Coated fibers that are carbides of tantalum, tungsten, niobium, zirconium, hafnium, or titanium. 8. The coating has a thickness of about 20 to 500 nm.
The coated fiber according to claim 1, which is 9. The thickness of the film is about 50 to 300 nm.
The coated fiber according to claim 1, which is 10. The coated fiber according to claim 1, wherein the coating has a fine structure having a particle size of about 5 to 75 nm. 11. The coated fiber according to claim 1, wherein the coating has a fine structure with a particle size of about 15 to 25 nm. 12. The coated fiber of claim 1, wherein the coating has 1 or less visible voids per 0.5 square micrometer area, the visible voids having 5 nanometers or greater. Coated fiber that is the size. 13. The coated fiber of claim 1, wherein the fiber is alpha-alumina and the coating is yttrium oxide. 14. A method for coating a ceramic metal or carbon fiber group comprising a continuous tow or bundle comprising: (a) applying sufficient current to a metal cathode to form a cathode material. Forming a plasma of atoms or ions of (b) arranging the fiber group in the path of the plasma,
A step of causing the plasma to inflate the fiber group; and (c) focusing the plasma on the surface of the fiber to form a heat-resistant metal or metal-based ceramic coating. 15. The method of claim 14, further comprising the step of supplying an inert gas to the plasma during step (a). 16. The method of claim 15, wherein the inert gas is selected from argon, krypton, xenon, helium, or an element of Group 8 of the periodic table. 17. The method of claim 14, further comprising the step of providing a reactive gas during step (a). 18. The method according to claim 17, wherein the reactive gas is a gas containing oxygen, nitrogen, ammonia, hydrocarbons or boron. 19. The metal fiber is tungsten or In
The method according to claim 14, which is a conel (trade name). 20. The method of claim 14, wherein the fibers are alumina, alumina-silica, alumina-boria-silica, boron, titanium diboride, silicon carbide, silicon nitride or boron nitride. 21. The method of claim 14, wherein the fibers are alpha-alumina or alumina-boria-silica.