JP2000045129A - High strength inorganic fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an oxide fiber which has high strength both at room temperature and at high temperature and has good oxidation resistance at high temperature. SOLUTION: A molten liquid composed of Ln (Ln is at least one rare earth metal element), A (A is at least one element selected from the group consisting of Al, Cr, Fe and Ga) and O is rotated with a rotating roll. A crystalline Ln ₃ A ₅ O ₁₂ produced by heating a fiber composed of Ln, A, and O produced by solidifying into a fine wire by heating at 700 to 1700 ° C. Phase, crystalline LnA
An amorphous phase composed of at least one crystalline phase selected from the group consisting of an O ₃ phase and a crystalline A ₂ O ₃ phase, and at least two elements selected from the group consisting of Ln, A and O; High-strength inorganic fiber composed of a solid phase.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inorganic fiber used for a wide variety of uses such as a heat insulating material, a filter material or a reinforcing material such as plastic, metal, ceramics, concrete and the like.

[0002]

2. Description of the Related Art For the purpose of improving the elastic modulus and high-temperature strength of metals, and improving the toughness of ceramics, Al ₂ O ₃ series,
Research and development for applying a continuous fiber such as SiC as a reinforcing material has been actively conducted. Al ₂ O ₃ fibers, since such it is relatively stable to oxidation resistance excellent can and molten metal at high temperatures, application to the applications are expected. However, Al ₂ O ₃ fibers, for example a tensile strength is not sufficiently high for the metal reinforcement, such as Ti and Ti-based alloys. Therefore, development of an oxide having good oxidation resistance at a high temperature and having high strength equal to or higher than that of Al ₂ O ₃ -based fiber has been desired.

[0003] US Patent No. 5,605,870 discloses that
Ceramic fibers made from a melt having a viscosity of 0 poises or less are disclosed. This fiber is produced by a so-called melt extraction method known per se, and is composed of an amorphous phase and / or a crystalline phase. However, according to the description of claim 1, "the crystal grain size is reduced to a linear matt surfaced l.
It is different from inorganic fibers in which the crystalline phase according to the present invention is uniformly dispersed in the fibers and has a uniform particle diameter.

[0004]

SUMMARY OF THE INVENTION In view of the above situation, the inventors of the present invention aimed at obtaining oxide fibers having high strength both at room temperature and at high temperatures and having good oxidation resistance at high temperatures. After intensive studies, they found a novel inorganic fiber described in the present invention. That is, Ln (Ln is at least one rare earth metal element), A (A is Al, Cr, Fe and G
a) a melt composed of at least one element selected from the group consisting of a) and O, cooled by contacting with a rotating roll, and solidified into a thin wire to produce Ln, A, and O.
Is prepared by heating the formed fibers at 700-1,700 ° C. from crystalline Ln ₃ A ₅ O ₁₂ phase, selected from the group consisting of A ₂ O ₃ phase crystalline LnAO ₃ phase and crystalline The inorganic fiber composed of at least one crystalline phase and an amorphous phase composed of at least two elements selected from the group consisting of Ln, A and O has a high temperature at room temperature and high temperature. It has been found to have strength.

An object of the present invention is to provide an inorganic material which has a large tensile strength from room temperature to a high temperature and can be suitably used for a wide range of other applications such as heat insulating materials, filter materials or reinforcing materials such as plastics, metals, ceramics and concrete. To provide fibers.

[0006]

Hereinafter, the present invention will be described in detail. The present invention relates to a crystalline Ln ₃ A ₅ O ₁₂ phase (Ln is at least one rare earth metal element, A is Al,
At least one element selected from the group consisting of Cr, Fe and Ga), crystalline LnAO ₃ phase and crystalline A
It is composed of at least one crystalline phase selected from the group consisting of ₂ O ₃ phases and an amorphous phase composed of at least two kinds of elements selected from the group consisting of Ln, A and O. The present invention relates to an inorganic fiber having extremely high strength in a temperature range of 1000 ° C.

[0007] The inorganic fiber is made of a molten material composed of Ln (Ln is at least one rare earth metal element), A (A is at least one element selected from the group consisting of Al, Cr, Fe and Ga) and O. Ln, A, which is produced by contacting the liquid with a rotating roll, cooling and solidifying the liquid into a thin line
And O at a temperature of 700 to 1700 ° C.

Here, “amorphous” means an atomic structure of a phase in which a crystal lattice image cannot be confirmed even by observation with a transmission electron microscope, and “crystalline” means a crystal structure obtained by observation with a transmission electron microscope. It means the atomic structure of a phase for which a lattice image can be confirmed.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, Ln is E
r, Yb, Dy, Y, Gd, La, Sm, Ce, Pr,
At least one rare earth metal element selected from the group consisting of Nd, Eu, Tb, Ho, Tm, and Lu is mentioned, and Er, Yb, and Dy are particularly preferable because the strength of the obtained inorganic fiber is increased.

A includes at least one element selected from the group consisting of Al, Cr, Fe and Ga. In particular, when A is Al and / or Cr, the obtained inorganic fiber has a high high-temperature strength. Is preferred.

The proportion of A in the inorganic fiber of the present invention is A
It is preferably in the range of 10 to 90 mol% in terms of ₂ O ₃ . Further, the shape of the inorganic fiber of the present invention is not particularly limited, but preferably has a circular or nearly circular cross section. The inorganic fibers of the present invention can be used both as continuous fibers and short fibers. The dimensions of the cross-section of the inorganic fiber are not limited to the cross-sectional shape, but preferably have a diameter of 3 to 50 μm, and more preferably have a diameter of 5 to 30 μm.

The tensile strength of the inorganic fiber of the present invention at room temperature, preferably at 1000 ° C., is desirably 2.5 GPa or more, preferably 3.0 GPa or more. The inorganic fiber of the present invention has extremely high strength and is 100% above room temperature.
In the temperature range up to 0 ° C., its strength shows almost no temperature dependence, and thus it is particularly useful as, for example, reinforcing fibers for metals such as Ti and Ti-based alloys.

The inorganic fiber of the present invention is composed of Ln, A, and O produced by contacting a molten liquid composed of Ln, A, and O with a rotating roll to cool and solidify the molten liquid into a fine wire. It is produced by heating fibers at 700-1700 ° C. Fibers before heating at 700 to 1700 ° C. (hereinafter referred to as intermediate fibers) are produced by the method described in Japanese Patent Application No. 9-353270. Hereinafter, the method will be described in detail.

As a raw material before melting, an oxide of Ln and an oxide of A are generally used, but any material which becomes an oxide when melted, such as hydroxide or carbonate, may be used. May be used. The form of the raw material may be any of a powder, a molded body, a sintered body, and a solidified body, or may be a combination of two or more of these.

The method for dissolving the raw material may be any method that can heat at least a portion of the raw material that comes into contact with the rotating roll to a temperature equal to or higher than its melting point. , Laser, electron beam, light, infrared, high frequency and the like can be used. When a high frequency is used, the raw material has little conductivity near room temperature, so it is necessary to store the raw material in a crucible having conductivity and a melting point higher than the melting point of the raw material. For example, crucibles such as Mo, W, Ta, Ir, and Nb are preferably used. Also, when the raw material is a powder, it is necessary to use a crucible or a support base of the above material,
In this case, in addition to the above crucible, a Cu crucible cooled with water or the like, a support, or the like can be used.
Even when the raw material is not a powder, these crucibles, supports, and the like can be suitably used.

The raw material may be dissolved in any atmosphere such as air, inert gas, reducing gas, hydrocarbon gas, or vacuum, but it is easily oxidized at a temperature lower than the melting point of the raw material. When a crucible or the like is used, the melting is preferably performed in an atmosphere of an inert gas such as an argon gas or a helium gas or in a vacuum. When the raw material is melted by the arc, it is necessary that the atmosphere contains an argon gas or the like sufficient to generate the arc.

The material of the rotating roll is not particularly limited,
A material having a high thermal conductivity or a metal having a high melting point is preferred from the viewpoint of the life of the roll and the stability of the quality of the obtained fiber. Specifically, Cu, Cu alloy, Mo, Ta, W, Ir and the like can be preferably used. The contact between the rotating roll and the melt may be in any form, for example, by bringing the tip of the rotating roll into rotating contact with the melt or dropping the melt onto the rotating roll. However, as the shape of the rotating roll, one that can contact the melt with a small area at the tip is convenient for making the cross-sectional shape of the obtained fiber uniform, for example, as shown in FIG. In addition, a rotating roll having a V-shaped protrusion at the tip can be suitably used.

It is desirable that the peripheral speed of the rotating roll when the rotating roll is brought into contact with the melt is 10 m / sec or less. If the peripheral speed is faster than 10m / sec,
This is because it may be difficult to obtain a fiber having a constant cross-sectional area.

As an apparatus for producing the intermediate fiber of the present invention, for example, an apparatus having a structure as shown in FIG. 2 can be used. A melt (4) composed of Ln, A, and O dissolved by an arc (3) generated between the W electrode (1) and a water-cooled Cu crucible (2) is mixed with Cu.
By moving the crucible horizontally, the crucible is brought into contact with a roll (5) rotating in the direction of the arrow, and solidified into a thin line to obtain an intermediate fiber (6) composed of the above elements.

The conversion from the intermediate fiber to the inorganic fiber of the present invention is carried out by heating the intermediate fiber at 700 to 1700 ° C. The heating method of the intermediate fiber is such that the fiber
Any method may be used as long as it can be heated to 1700 ° C., and as a heating source, for example, a heating element such as SiC or MoSi _{2 that} generates heat by energization, a high frequency, a laser, an electron beam, light, infrared, or the like is used. be able to.

Generally, the intermediate fiber is placed in a crucible made of ceramics such as Al ₂ O ₃ or SiC, or a high melting point metal such as Mo, Ta, W, Ir, or Nb, and the whole crucible is heated. Alternatively, a method of winding the intermediate fiber around a drum made of a similar material and heating the entire drum is used. In addition, a method of continuously passing fibers into the furnace of a tubular furnace heated to a predetermined temperature can be applied. In order to obtain a fiber having higher strength, unidirectional heating may be performed such that the intermediate fiber is gradually heated from one side of the fiber in the fiber direction so that the crystal grows in the fiber direction. The heat treatment in this case is also possible by a method of continuously passing the fiber into the furnace of the tubular furnace as described above, but using a laser, an electron beam, light, infrared rays, etc., the fiber or the portion to be heated. A method of moving in the fiber direction can also be applied.

The heat treatment of the intermediate fiber may be performed in any atmosphere such as the atmosphere, an inert gas, a reducing gas, a hydrocarbon gas, or a vacuum. May be subject to restrictions.

[0023]

The present invention will be described more specifically below with reference to examples and comparative examples. Example 1 α-Al ₂ O ₃ powder and Er ₂ O ₃ powder were used as raw materials. α-Al ₂ O ₃ powder and Er ₂ O ₃ powder were mixed at a molar ratio of 81.1 by the former and 18.9 by the wet ball mill using ethanol at a ratio of 18.9, and the resulting slurry was subjected to rotary evaporation using a rotary evaporator. To remove the ethanol. The obtained mixed powder was formed into a cylindrical shape having a diameter of 10 mm and a height of 10 mm by a uniaxial press using a stainless steel die, and then the cylindrical formed body was melted by an arc to obtain a button-shaped solidified body. This button-shaped solidified body is housed in a water-cooled Cu crucible (2) shown in FIG.
The system in which the mechanism of FIG. 2 is housed was set to an argon gas atmosphere of -0.04 MPa, and an arc was generated between the W electrode and the Cu crucible. The button-shaped solidified body is melted by the arc,
While maintaining the molten state, the Cu crucible was moved and brought into contact with a 70 mm diameter Cu roll having a 30 ° V-shaped projection at the tip rotating at a peripheral speed of 2 m / sec.
A continuous fiber having an average diameter of 15 μm was obtained. Next, this intermediate fiber was accommodated in a crucible made of Al ₂ O ₃ , and was subjected to heat treatment in air using a box-type electric furnace equipped with a heating element made of MoSi ₂ . The temperature was raised at a rate of 1000 ° C./hr,
After holding at 2 ° C. for 2 hours, the temperature was lowered to obtain continuous fibers having an average diameter of 15 μm. The obtained fiber was X-ray using Cu-Kα ray.
X-ray diffraction, observation by transmission electron microscope, and analysis of characteristic X-rays by a semiconductor X-ray detector installed in the transmission electron microscope,
Er ₃ Al ₅ O ₁₂ crystal phase of a plurality of 20 to 30 nm, a plurality of 20 to 30 nm Al ₂ O ₃ crystal phase and Er, Al, are composed of amorphous phase consisting O, each phase fibers It was found that they existed uniformly dispersed therein. Also,
The tensile test of this fiber was performed at a load speed of 2 mm / mi at room temperature.
n, 25 mm span and in the air at 1000 ° C., the load speed was 2 mm / min, and the span was 100 mm. Table 1 shows the average values of the measured tensile strength at room temperature and at 1000 ° C.

Example 2 Example 1 was repeated except that α-Al ₂ O ₃ powder and Yb ₂ O ₃ powder were used as raw materials, and the mixing ratio was 83.7 for the former and 16.3 for the latter in molar ratio. Continuous fibers were obtained in the same manner. The obtained fiber was analyzed by the same analysis as in Example 1 to obtain a plurality of fibers.
Yb ₃ Al ₅ O ₁₂ crystal phase of ３０30 nm;
It was found that the fiber was composed of an Al ₂ O ₃ crystal phase of nm and an amorphous phase composed of Yb, Al, and O, and each phase was found to be uniformly dispersed in the fiber. Table 1 shows the results of a tensile test performed on the fiber in the same manner as in Example 1.

Example 3 Example 1 was repeated except that α-Al ₂ O ₃ powder and Dy ₂ O ₃ powder were used as raw materials, and the mixing ratio of the former was 78.9 and the latter was 21.1. Continuous fibers were obtained in the same manner. The obtained fiber was analyzed by the same analysis as in Example 1 to obtain a plurality of fibers.
Dy ₃ Al ₅ O ₁₂ crystal phase of ３０30 nm, multiple
It was found to be composed of an Al ₂ O ₃ crystal phase of nm and an amorphous phase composed of Dy, Al, O, and each phase was found to be uniformly dispersed in the fiber. Table 1 shows the results of a tensile test performed on the fiber in the same manner as in Example 1.

Example 4 α-Al as raw material_TwoO_ThreePowder and Y_TwoO_ThreeUsing powder
Except that the mixing ratio was 82 for the former and 18 for the latter in molar ratio
Continuous fibers were obtained in the same manner as in Example 1. The resulting fiber
Is the same analysis as in Example 1,
Y_ThreeAl _FiveO₁₂Crystal phase, multiple 20-30nm Al_TwoO
_ThreeConsists of a crystalline phase and an amorphous phase composed of Y, Al, O
Each phase is evenly distributed in the fiber
I knew it was there. In addition, a tensile test was performed on this fiber.
Table 1 shows the results obtained in the same manner as in Example 1.

Example 5 α-Al ₂ O ₃ powder and Gd ₂ O ₃ powder were used as raw materials, the mixing ratio of which was 78 for the former and 22 for the latter, and the heat treatment temperature of the intermediate fiber was 1000 ° C. Example 1 except that
Continuous fibers were obtained in the same manner as described above. The obtained fiber was analyzed by the same analysis as in Example 1 to obtain a plurality of 15-25 nm GdAl.
It is composed of an O ₃ crystal phase, a plurality of 15 to 25 nm Al ₂ O ₃ crystal phases, and an amorphous phase composed of Gd, Al, and O. Each phase exists uniformly dispersed in the fiber. I knew it was there. Table 1 shows the results of a tensile test performed on the fiber in the same manner as in Example 1.

Example 6 A method similar to that of Example 5 was used except that α-Al ₂ O ₃ powder and Sm ₂ O ₃ powder were used as raw materials, and the mixing ratio of the former was 69 and the latter was 31. A continuous fiber was obtained. The obtained fiber was analyzed by the same analysis as in Example 1 to obtain a plurality of fibers of 15 to 25 nm.
SmAlO ₃ crystal phase, multiple 20-30 nm Al ₂ O
It was composed of _three crystalline phases and an amorphous phase composed of Sm, Al and O, and it was found that each phase was uniformly dispersed in the fiber. Table 1 shows the results of a tensile test performed on the fiber in the same manner as in Example 1.

Example 7 α-Al ₂ O ₃ powder and La ₂ O ₃ powder were used as raw materials, and the mixing ratio was 77.5 for the former and 22.5 for the latter in molar ratio. Was changed to 1 m / sec, and continuous fibers were obtained in the same manner as in Example 5. The obtained fiber was analyzed by the same analysis as in Example 1 to obtain a plurality of 15-25 nm LaAlO ₃ crystal phases and a plurality of 15-25 nm Al ₂ O _3.
It was found that it was composed of a crystalline phase and an amorphous phase composed of La, Al, and O, and each phase was found to be uniformly dispersed in the fiber. Table 1 shows the results of a tensile test performed on the fiber in the same manner as in Example 1.

Example 8 Continuous fiber was prepared in the same manner as in Example 1 except that Cr ₂ O ₃ powder and Er ₂ O ₃ powder were used as raw materials, and the mixing ratio was 78 for the former and 22 for the latter. I got The obtained fiber was subjected to the same analysis as in Example 1 to obtain a plurality of 25-35 nm E.
It is composed of an rCrO ₃ crystal phase, a plurality of 25-35 nm Cr ₂ O ₃ crystal phases, and an amorphous phase composed of Er, Cr, O. Each of the phases is uniformly dispersed in the fiber. I knew it was there. Table 1 shows the results of a tensile test performed on the fiber in the same manner as in Example 1.

Example 9 Continuous fiber was prepared in the same manner as in Example 1 except that Cr ₂ O ₃ powder and Gd ₂ O ₃ powder were used as raw materials, and the mixing ratio of the former was 80 and the latter was 20. I got The obtained fiber was analyzed by the same method as in Example 1 to obtain a plurality of G fibers of 20 to 30 nm.
It is composed of a dCrO ₃ crystal phase, a plurality of 20-30 nm Cr ₂ O ₃ crystal phases, and an amorphous phase composed of Gd, Cr, O. Each phase is uniformly dispersed in the fiber. I knew it was there. Table 1 shows the results of a tensile test performed on the fiber in the same manner as in Example 1.

Example 10 The same procedure as in Example 1 was carried out except that Ga ₂ O ₃ powder and Gd ₂ O ₃ powder were used as raw materials, and the mixing ratio was 69.2 for the former and 30.8 for the latter in molar ratio. Continuous fiber was obtained by the method. The obtained fiber was analyzed by the same analysis as in Example 1 to obtain a plurality of fibers.
It is composed of a 0 nm Gd ₃ Ga ₅ O ₁₂ crystal phase, a plurality of 20-30 nm Ga ₂ O ₃ crystal phases and an amorphous phase composed of Gd, Ga, O, and each phase is uniformly distributed in the fiber. It was found that they existed dispersedly. Table 1 shows the results of a tensile test performed on the fiber in the same manner as in Example 1.

Comparative Example 1 α-Al as a raw material_TwoO_ThreePowder and ZrO_TwoUsing powder
The mixing ratio was 62 in the former and 38 in the latter by molar ratio.
Example except that the peripheral speed of the roll was set to 0.5 m / sec.
Continuous fibers were obtained in the same manner as in Example 5. The obtained fiber is implemented
By the same analysis as in Example 1, a plurality of 30-400 nm Zr
O _TwoCrystal phase, multiple 20-250nm Al_TwoO_ThreeCrystal phase
And an amorphous phase composed of Zr, Al, and O
The relatively coarse crystal phase radiates from the roll contact area.
It turned out that it grew linearly. In other words, this fiber
Was found to be heterogeneous. Also this fiber
Table 1 shows the results of the same tensile test as in Example 1.
Show.

[0034]

[Table 1]

[0035]

According to the present invention, an oxide having good oxidation resistance at a high temperature, a large tensile strength from room temperature to a high temperature, a heat insulating material, a filter material or a plastic, a metal,
Provided is an inorganic fiber that can be suitably used for a wide range of other uses such as reinforcing materials such as ceramics and concrete.

[Brief description of the drawings]

FIG. 1 is a drawing showing an example of the shape of a rotating roll used for producing an inorganic fiber intermediate fiber of the present invention.

FIG. 2 is a drawing showing an example of a mechanism of an apparatus used for producing an intermediate fiber of an inorganic fiber of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... W electrode 2 ... Cu crucible 3 ... Arc 4 ... Molten liquid 5 ... Roll 6 ... Intermediate fiber

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshiharu Waku, 5-1978 Kogushi, Oji, Ube City, Yamaguchi Prefecture Inside Ube Research Institute, Ltd. Ube Research Laboratory Co., Ltd. (72) Inventor Hideki Otsubo 1978 Kogushi, Ube City, Ube City, Yamaguchi Prefecture Ube Kosan Co., Ltd. Ube Research Laboratory F Term (Reference) DA15 DA20

Claims (5)

[Claims] 1. Rotating a molten liquid composed of Ln (Ln is at least one rare earth metal element), A (A is at least one element selected from the group consisting of Al, Cr, Fe and Ga) and O cooled by contact with a roll, Ln is produced by solidifying the thin line, is prepared by heating a, and the fibers consisting of O at 700 to 1,700 ° C., the crystalline Ln ₃ a ₅ O ₁₂ phase, crystalline LnA
An amorphous phase composed of at least one crystalline phase selected from the group consisting of an O ₃ phase and a crystalline A ₂ O ₃ phase, and at least two elements selected from the group consisting of Ln, A and O; High-strength inorganic fiber composed of a solid phase. 2. The method according to claim 1, wherein A is Al and / or Cr.
The high-strength inorganic fiber according to the above. 3. The high-strength inorganic fiber according to claim 1, wherein the crystalline phase is uniformly dispersed in the fiber and has a uniform particle size. 4. The method according to claim 1, wherein the rare earth metal element is Er, Yb, Dy,
Y, Gd, La, Sm, Ce, Pr, Nd, Eu, T
4. At least one element selected from the group consisting of b, Ho, Tm and Lu.
The high-strength inorganic fiber according to 1. 5. The method according to claim 1, wherein the rare earth metal element is Er, Yb and Dy.
The high-strength inorganic fiber according to claim 4, which is at least one element selected from the group consisting of: