JP2000045128A - High heat resistant inorganic fiber - Google Patents

Abstract

(57) [Problem] To provide an inorganic fiber having high tensile strength from room temperature to 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 by 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 LnAO
High heat-resistant inorganic fiber composed of at least two kinds of crystalline phases selected from the group consisting of _three phases and crystalline A ₂ O ₃ 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 such as, for example, its intensity decreases at 1200 ° C. or higher, is not sufficiently high heat resistance for the ceramic reinforcement. Therefore, development of an oxide having good oxidation resistance at a high temperature and having high heat resistance 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 linear.
It is different from inorganic fibers in which each crystalline phase according to the present invention is uniformly dispersed in the fibers and has a uniform particle diameter. It is.

[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
Ln, A, and O produced by contacting a molten liquid composed of at least one element selected from the group consisting of a) and O with a rotating roll, cooling, and solidifying into a fine wire shape.
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 It has been found that the inorganic fiber composed of at least two types of crystalline phases has high strength both at room temperature and at high temperature.

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
_{The present invention} relates to an inorganic fiber composed of at least two types of crystalline phases selected from the group consisting of ₂ O ₃ phases and having high strength in a temperature range from room temperature to 1200 ° 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 into a fine line
And O at a temperature of 700 to 1700 ° C. Here, “crystalline” means an atomic structure of a phase in which a crystal lattice image can be confirmed by transmission electron microscope observation.

[0008]

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 . The inorganic fibers of the present invention are Ln ₃ A ₅ O ₁₂ , LnAO
_3, A consists of substantially only the crystalline phase comprised of at least in two crystalline phases (e.g., A ₂ O ₃ even Different A different crystal phases) selected from the group of the crystal phase represented by ₂ O ₃ However, there may be an amorphous phase at the grain boundaries. 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 1200 ° C., is desirably 1.5 GPa or more, preferably 2.0 GPa or more. The inorganic fiber of the present invention has a high strength, and its strength shows almost no temperature dependence in a temperature range from room temperature to 1200 ° C., for example, as a reinforcing fiber for ceramics or a heat insulating material for a high-temperature furnace. Particularly useful.

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 that can be converted to 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 of melting the raw material may be any method capable of heating 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 the atmosphere, an inert gas, a reducing gas, a hydrocarbon gas, or a vacuum, but 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 suitably 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 mechanism 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 desired inorganic fiber can be obtained by appropriately selecting the temperature and time of the heat treatment, the rate of temperature rise and fall, and the like. The heating method of the intermediate fiber is such that the fiber is 700-170.
Any method may be used as long as it can be heated to 0 ° C., and as a heating source, for example, a heating element such as SiC or MoSi _{2 that} generates heat when energized, a high frequency, a laser,
An electron beam, light, infrared light, or the like can be used.

Generally, the intermediate fibers are housed in a crucible made of a ceramic such as Al ₂ O ₃ or SiC, or a high melting point metal such as Mo, Ta, W, Ir or Nb, and heated together with the crucible. 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 air, an inert gas, a reducing gas, a hydrocarbon gas, or a vacuum. May be subject to restrictions.

[0022]

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 14 μm. The obtained fiber was X-ray using Cu-Kα ray.
A plurality of 100-
150nm of Er ₃ Al ₅ O ₁₂ phase and a plurality of 100 to 15
It was crystalline composed of an Al ₂ O ₃ phase of 0 nm, and it was found that each crystalline phase was uniformly dispersed in the fiber. The tensile test of this fiber was carried out under the conditions of a load speed of 2 mm / min and a span of 25 mm at room temperature.
Load speed 2mm / min in air at 1200 ℃ and 1200 ℃
And a span of 100 mm. Measured room temperature,
Table 1 shows the average values of the tensile strength at 1000 ° C and 1200 ° C.
Shown in

Example 2 α-Al as raw material_TwoO_ThreePowder and Yb_TwoO_ThreeUse powder
The molar ratio of the former was 83.7 and the latter was 16.3.
A continuous fiber was obtained in the same manner as in Example 1 except that the procedure was repeated. Profit
The fibers obtained were analyzed by the same analysis as in Example 1 to obtain a plurality of fibers.
0 to 150 nm Yb _ThreeAl_FiveO₁₂Phases and multiple 100-
150nm Al_TwoO_ThreeCrystalline composed of phases,
Each crystalline phase must be uniformly dispersed in the fiber.
I understood. In addition, the tensile test of this fiber was performed as in Example 1.
Table 1 shows the results obtained in the same manner.

Example 3 α-Al as raw material_TwoO_ThreePowder and Dy_TwoO_ThreeUse powder
The molar ratio of the former was 78.9, and the latter was 21.1.
A continuous fiber was obtained in the same manner as in Example 1 except that the procedure was repeated. Profit
The fibers obtained were analyzed by the same analysis as in Example 1 to obtain a plurality of fibers.
Dy from 0 to 150 nm _ThreeAl_FiveO₁₂Phases and multiple 100-
150nm Al_TwoO_ThreeCrystalline composed of phases,
Each crystalline phase must be uniformly dispersed in the fiber.
I understood. In addition, the tensile test of this fiber was performed as in Example 1.
Table 1 shows the results obtained in the same manner.

Example 4 The same method as in Example 1 was used except that α-Al ₂ O ₃ powder and Y ₂ O ₃ powder were used as raw materials, and the mixing ratio was 82 for the former and 18 for the latter in molar ratio. A continuous fiber was obtained. The obtained fiber was analyzed by the same analysis as in Example 1 to obtain a plurality of fibers.
nm of Y ₃ Al ₅ O ₁₂ phase and the A of the plurality of 150~200nm
It was found to be crystalline composed of the l ₂ O ₃ phase, and it was found that each of the crystal phases 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 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 1300 ° C. Example 1 except for
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 Gd of 120 to 160 nm.
It was crystalline composed of an AlO ₃ phase and a plurality of Al ₂ O ₃ phases of 120 to 160 nm, and it was found that each crystalline 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 6 The same method as in 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 was 69 for the former and 31 for the latter in molar ratio. 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 120 to 16 pieces.
0 nm SmAlO ₃ phase and multiple 120-160 nm A
It was found to be crystalline composed of the l ₂ O ₃ phase, and it was found that each of the crystal phases 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 terms of 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 fibers of 120 to 160.
nm LaAlO ₃ phase and multiple 120-160 nm Al
It was crystalline composed of the ₂ O ₃ phase, and it was found that each of the crystalline phases 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 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 analyzed by the same analysis as in Example 1 to obtain a plurality of fibers of 150 to 200 nm.
ErCrO ₃ phase and a plurality of 150 to 200 nm Cr ₂
It was found to be crystalline composed of the O ₃ phase, and it was found that each of the crystalline phases 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 9 Continuous fiber was produced 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 was 80 for the former and 20 for the latter in molar ratio. I got The obtained fiber was analyzed by the same analysis as in Example 1 to obtain a plurality of fibers of 150 to 200 nm.
GdCrO ₃ phase and multiple 150-200 nm Cr ₂
It was found to be crystalline composed of the O ₃ phase, and it was found that each of the crystalline phases 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 10 Ga as a raw material_TwoO_ThreePowder and Gd_TwoO_ThreeUse powder and mix
The molar ratio was 69.2 for the former and 30.8 for the latter.
Except for the above, continuous fibers were obtained in the same manner as in Example 1. Obtained
The fibers obtained were analyzed by the same analysis as in Example 1, and
200nm Gd _ThreeGa_FiveO₁₂Phases and multiple 150-20
0 nm Ga_TwoO_ThreeCrystalline composed of phases
That the crystalline phase is uniformly dispersed in the fiber
all right. Further, the tensile test of this fiber was performed in the same manner as in Example 1.
Table 1 shows the results.

Comparative Example 1 α-Al ₂ O ₃ powder and ZrO ₂ powder were used as raw materials, and the mixing ratio was 62 for the former and 38 for the latter, and the peripheral speed of the rotating roll was 0.5 m / sec. Continuous fiber was obtained in the same manner as in Example 5 except that the above procedure was repeated. The obtained fiber was composed of a plurality of 100-1500 nm ZrO ₂ phases and a plurality of 100-1000 nm Al ₂ O ₃ phases by the same analysis as in Example 1, and the relatively coarse crystal phase was rolled. It was found that it grew radially from the contact part.
That is, it was found that the structure of the fibers was uneven. Table 1 shows the results of a tensile test performed on the fiber in the same manner as in Example 1.

[0033]

[Table 1]

[0034]

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 of Ube Research Institute, Ltd. (72) Inventor Toshi Nakagawa 578, 1978 Kogushi, Ube City, Ube City, Yamaguchi Prefecture Ube Industries, Ltd. Inside Ube Research Laboratories (72) Inventor Hideki Otsubo 1978 Kogushi, Ube City, Ube City, Yamaguchi Prefecture Ube Industries, Ltd. Ube Research Laboratories F Term (Reference) 4L037 CS17 CS22 FA03 FA05 PA31 PA32 UA06 UA07 UA10 UA12 UA15

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 A crystalline Ln ₃ A ₅ O produced by heating a fiber composed of Ln, A, and O produced by contacting with a roll and cooling to form a fine wire at 700 to 1700 ° C. ₁₂ phase, crystalline LnA
A highly heat-resistant inorganic fiber composed of at least two types of crystalline phases selected from the group consisting of an O ₃ phase and a crystalline A ₂ O ₃ phase. 2. The method according to claim 1, wherein A is Al and / or Cr.
The highly heat-resistant inorganic fiber as described. 3. The highly heat-resistant inorganic fiber according to claim 1, wherein each of the crystalline phases is uniformly dispersed in the fiber, and has a uniform particle diameter. 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.
Highly heat-resistant inorganic fiber according to 1. 5. The method according to claim 1, wherein the rare earth metal element is Er, Yb and Dy.
The highly heat-resistant inorganic fiber according to claim 4, wherein the inorganic fiber is at least one element selected from the group consisting of: