JPH01157459A - Production of article of long sized sintered body - Google Patents

Abstract

PURPOSE:To obtain articles of long sized sintered body having high orientation characteristic and high density with high productivity in high yield by filling raw material powder in a metallic cylinder, working the cylinder plastically, sintering the raw material powder by heating in a magnetic field, and cooling the cylinder thereafter. CONSTITUTION:Raw material powder such as BaCO3, Y2O3, CuO, etc., is filled in a metallic cylinder (e.g., silver pipe) suitable for plastic working. After subjecting the metallic cylinder contg. the raw material powder to plastic working, the raw material powder is calcined or sintered by heating in a magnetic field. Then, a long sized sintered article is obtd. by cooling said cylinder. Since the magnetic field is applied after the sintering stage, the orientation of the tissue of the sintered body, particularly, the electromagnetic characteristic thereof is improved. Accordingly, the critical current density, etc., of the product is improved, when this method is applied, particularly, to the production of a compound oxide superconducting material.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for manufacturing long sintered products. The body,
In particular, the present invention relates to a novel manufacturing method for making difficult-to-process powder materials unsuitable for processes such as wire drawing and rolling into long products such as wires and tapes.

BACKGROUND OF THE INVENTION Ceramics used to belong to a field called the ceramic industry, and were widely used industrially as products such as ceramics, refractories, glass, enamel, and cement.

However, now that the development of metallic and organic materials has reached its peak, so-called fine ceramics, in which new inorganic materials have specific functions, are being used in an extremely wide range of fields in search of new possibilities. It is being

In addition to electrical insulation, heat resistance, and corrosion resistance, which have long been known as properties of ceramics, these fine ceramics also exhibit hardness, piezoelectricity, and depending on the material, high thermal conductivity and electrical conductivity. There is also. Furthermore, with the recent advances in manufacturing technology, materials having functions such as magnetism, translucency, fluorescence, and biocompatibility have also been developed. In this way, the elements that make up ceramics and their combinations, as well as their functions, are extremely diverse.

Here, ceramics refers to sintered bodies that include not only general inorganic materials but also metals, and generally refers to those obtained by in-phase reaction of powder materials. To name a few examples, oxide-based alumina including complex oxides, beryllia, manganese ferrite) ((!, In, Zn) Fe
20s:l, P L Z T ((Pb, L
a) (Zr, Ti)03] or non-oxide S
In addition to nitride-based, carbide-based, silicide-based, boride-based, and sulfide-based alloys such as i3N, AIN, partially stabilized zirconia, and SiC, sintered alloys such as tungsten carbide, carbide precipitation-strengthened cobalt-based alloys, and various forms of Carbon also belongs to this field in a broad sense.

Alumina was first put to practical use in thread guides, bearings, tools, etc., and recently, with the rise of electronics, it has come to be widely used in integrated circuit packages, substrates, etc.

Cemented carbide containing tungsten carbide or cobalt as a bonding metal has high hardness and excellent toughness, and is therefore used as cutting tools and wear-resistant parts. It is also used in precision machinery such as the printing section of dot impact printers.

Silicon nitride, silicon carbide, etc. have excellent high-temperature strength and excellent wear resistance, so they are used particularly in high-temperature areas, such as rolls for conveying and processing high-temperature products, and parts around the combustion system of internal combustion engines. It is used as a heat-resistant structural material.

Problems to be Solved by the Invention As mentioned above, various sintered products are being used in a wide variety of fields due to their excellent properties. However, the fact that a general characteristic of a sintered body is its strength or hardness makes processing the sintered body extremely difficult. That is, processing of a member that has become a sintered body through a sintering process is limited to electrical discharge machining or grinding using a diamond grindstone, and so-called plastic processing such as rolling or wire drawing is extremely difficult. Therefore, it is extremely difficult to industrially manufacture products in the form of wires or tapes, or long materials such as pipes.

Therefore, when manufacturing long ceramic products, the raw material powder is formed into a long shape before the sintering process, and the processing after sintering is minimized by sintering after forming. We are working on this.

In the production of rods used for shafts and the like, a method is employed in which a molded body is stamped into a square shape, shaped into a rod by cutting, and then sintered. However, this method has problems such as the poor yield of expensive raw material powder, the inability to obtain sufficient length for the cross-sectional dimension due to the cutting process, and the fact that the cutting process is not suitable for continuous processing, resulting in low productivity. There is a problem. Another method, such as the doctor blade method, is to mix an organic adhesive into raw material powder, extrude it and form it into a linear or tape shape, and then use intermediate sintering to create an organic adhesive. There is a method of performing main sintering after volatilizing the agent. This method has good utilization efficiency of raw material powder,
The dimension ratio of the longitudinal direction to the cross-sectional direction of the rod is also arbitrary,
Excellent productivity.

However, there is a problem in that it is difficult to completely remove the adhesive mixed with the raw material powder, and the remaining adhesive reduces the strength of the product or causes defects.

As described above, it is generally difficult to manufacture high-quality long products using sintered bodies using powder raw materials using conventional techniques. Furthermore, even if it were possible, the productivity would be extremely low, making the product extremely expensive and limiting its range of use.

Furthermore, even in metal-based sintered products such as carbide precipitation-strengthened CO-based alloys, it is still difficult to manufacture long products. In the case of metal, in addition to the above methods, ■
Centrifugal casting method, ■ Rotary underwater spinning method, ■ Plating method, etc. are applicable.

However, although the "■ centrifugal casting method" is a relatively easy method, it is difficult to cast long pieces with a small diameter, and currently the diameter is 2 mm.
The maximum diameter of the wire rod is 5Qcm. Furthermore, defects tend to occur at the center of the thin wire, making it difficult to manufacture high quality thin wires. The "Rotary underwater spinning method" is an advantageous method for forming fine wires, but it has the problem that precise control of the wire diameter is difficult and the wire diameter is limited to about 1 mm or less. "■Plating method" is a method that uses Co5 on a fibrous base material such as carbon fiber.
This is a method of plating WSCr etc. and thermally diffusing it, but in particular W
The problem is that there are materials that are very difficult to plate, such as , and that productivity is very low.

As described above, there is a need to establish an industrial manufacturing technology for long products, which is a problem that is almost common to all sintered materials. In contrast, the present applicant has filed Japanese Patent Application No. 121733/1983,
Japanese Patent Application No. 63-25108, Japanese Patent Application No. 63-46970, Japanese Patent Application No. 63-94155, Japanese Patent Application No. 63-94155
In order to solve the above problems, in order to solve the above problems, raw material powder is filled inside a metal cylinder suitable for plastic working, and after plastic working of the cylinder containing the raw material powder, the cylinder is heated. We have proposed a method for manufacturing a long sintered product, which includes a step of firing or sintering the raw material powder.

Although each of these methods has an effective inventive step, there is a need to further improve the quality of the sintered products produced by the above methods, particularly the toughness, strength, and electrical conductivity. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a novel method for manufacturing long sintered body products that can produce high quality long sintered body products with high productivity and good yield.

Means for Solving the Problems According to the present invention, a step of filling a raw material powder into the inside of a metal cylinder suitable for plastic working, a step of plastic working the cylinder containing the raw material powder, and a step of filling the inside of a metal cylinder suitable for plastic working, a step of plastic working the cylinder containing the raw material powder, A long sintered product comprising the steps of heating a cylindrical body containing powder to fire or sinter the raw material powder, and cooling the cylindrical body containing the fired or sintered raw material powder. In the manufacturing method, there is provided a method characterized in that, after the step of firing or sintering the raw material powder, any or all of the steps described above are performed in a magnetic field.

Function The method for producing a long sintered product according to the present invention is characterized in that a magnetic field is applied in the steps after the sintering step. That is, by applying a magnetic field to the sintered body or the raw material in its production process, the orientation of the structure of the sintered body is improved, and as a result, the properties of the final sintered product, particularly the electromagnetic properties, are improved. Therefore, the present invention can be advantageously applied to the production of long sintered bodies having anisotropic properties, for example, to the production of composite oxide-based superconducting materials, described below, which generally have anisotropy with respect to electric current. can.

Here, since the application of a magnetic field favorably contributes to the formation of the structure of the sintered body, it is preferable to apply the magnetic field continuously in all steps from the firing or sintering step to the cooling step. Further, the direction of the applied magnetic field is determined according to the direction of electromagnetic properties, crystal anisotropy, etc. to be imparted to the final sintered product. This direction can be determined by experiment. Further, the strength of the applied magnetic field is generally preferably in the range of 25 to 200 kA/m. Application of the magnetic field can be carried out using a well-known magnetic field generator, and a coil, a flat magnetic pole, a permanent magnet, etc. can be used in an appropriate combination according to the direction of the magnetic field to be applied.

It should be noted that the premise of the present invention is ``a step of filling a raw material powder into the inside of a metal cylinder suitable for plastic working, a step of plastic working the cylinder containing the raw material powder, and a step of filling the inside of a metal cylinder suitable for plastic working. ``A method for manufacturing a long sintered product, which includes a step of heating a cylinder to fire or sinter the raw material powder, and a step of cooling the cylinder containing the fired or sintered raw material powder.'' , the above-mentioned patent application 1982-121 filed by the above-mentioned applicant.
No. 733, Patent Application No. 1983-25108, Patent Application No. 1983-4
No. 6970, Patent Application No. 1983-94155, Patent Application No. 1983-
No. 94155.

That is, in the method of the present invention, plastic working preferably involves compressive stress acting on the workpiece, and by performing such working hot, the raw material powder housed in the metal cylinder is densified. It can be formed into. Therefore,
By sintering the raw material powder that has undergone such treatment, it is possible to form a sintered body with high density. Further, more specifically, wire drawing processing, forging, etc. are included, and furthermore, it should be understood that it is within the scope of the present invention to carry out both or a combination of various processing methods including both. . Furthermore, in the method of the present invention, any plastic working in which compressive stress is applied to the workpiece may be used, such as rolling of a tape-shaped member, diameter reduction of a tube having a rectangular cross section, and even coiling of a wire rod. It should be interpreted that it also includes processing to form into shapes, etc.

In addition, in the step of plastic working, it is particularly preferable to perform a process that includes hot plastic working. Here, r hot time.”
This means that the cylindrical body during plastic working is heated to a temperature higher than the recrystallization temperature of the metal forming the cylindrical body.

In other words, in this temperature range, the deformation resistance of the metal decreases significantly and it exhibits extremely high malleability, and even if recrystallization occurs after cooling down, no work hardening remains, so plastic working can be advantageously performed. can. In hot working and drilling, it goes without saying that once the metal melts, plastic working is no longer possible, and in practice it is practical to work at a temperature about 10°C lower than the melting point of the metal. be.

Processing methods that can be applied to wire drawing include dies,
Roller die, rolling pedestal swaging unit,
Any conventionally known metal plastic working method using an extruder or the like can be applied, and these should be appropriately selected depending on the material. In addition, swaging can be mentioned as a processing method that can be advantageously applied as a forging process.

Furthermore, the quality of the product can be further improved by performing these various plastic working methods successively or alternately.

Here, different processing methods include processing with different purposes such as wire drawing and forging, processing using different means such as die wire drawing and swaging, and hot plastic processing and cold plastic processing. This includes processing that has different processing conditions such as. In addition, the repetition of plastic working mentioned here is
This is done before the final sintering or firing step.

On the other hand, if a sintering treatment is performed after these plastic workings, a gap may occur between the metal cylinder and the internal sintered body due to shrinkage during sintering. Therefore, it is also advantageous to perform a series of treatments including plastic working anew after the sintering treatment. For these reasons, when the plastic working knee sintering process is repeated multiple times, it is also advantageous to include a process in which the plastic working is performed cold.

The cylinder is made of Fe5Ni, Co, Ag5AuSPt.
, Cu.

It can be made of a metal selected from the group consisting of AI or an alloy containing said metal.

Now, as a sintered body material to which the method of the present invention can be particularly advantageously applied, a composite oxide-based superconducting material can be mentioned. This composite oxide-based superconducting material is a composite oxide of the type 2NiF, a, Ba) 2CuO, [Bedno
rz, 1ller, ”Z, Phys, 864
．． 1986.189”]. In other words, it refers to a series of composite oxide superconducting materials including oxide superconductors (La,
Ba), CuO4 has a similar crystal structure to conventionally known perovskite-type superconducting oxides, but its superconducting critical temperature T.

is dramatically higher than that of conventional superconducting materials, at about 30.

It has already been known that composite oxide-based ceramic materials exhibit superconducting properties; for example,
U.S. Pat. No. 3,932,315 describes Ba-Pb-B.
It is described that i-based composite oxides exhibit superconducting properties. Also, in Japanese Patent Application Laid-Open No. 60-173.885, B
It has been described that a-B1-based composite oxides exhibit superconducting properties. However, until now known complex oxide T. is below IOK, and the use of rare and expensive liquid helium (boiling point >4.2 K) was unavoidable in order to obtain superconducting phenomena.

Furthermore, in February 1987, Ba
-Y-based complex oxide has been discovered. This Ba-Y complex oxide called YBCO is YIBa2CU30
It has a composition expressed as 7-x and exhibits a critical temperature of class 90.

It is known that the crystal structure of these composite oxide-based superconducting materials has a clear anisotropy between the direction of current flow and the critical current density, but when created as a sintered body, However, it was not possible to control the crystal direction or orientation of the product, and it was not possible to manufacture a product that could be used as a practical conductive material. On the other hand, when the method according to the present invention is applied, the crystal orientation in the sintered body is improved, and a significant increase in superconducting critical current density can be realized.

The composite oxide-based superconducting material to which the method of the present invention is applicable includes one element α selected from the elements of group 11a of the periodic table, and one element α selected from the elements of group II [a of the periodic table]. A composite oxide of β and at least one element γ selected from elements of group ib, nb, mb, IVa, and group ①a of the periodic table is preferred. Note that the element T is generally copper (Cu). That is, more specifically, the general formula: (α+−xI3x)
Cu, O.

[However, α and β are the elements defined above, and X is α
The atomic ratio of β to +β is a number that satisfies 0.1≦X≦0.9, and y and 2 are the atomic ratios when (αI−UβX) is 1, and 0.4≦y≦3. 0.1.0≦2≦5.0] It is a composite oxide having a composition represented by the following. Here, as a particularly preferable combination of elements, the element α is Ba or Sr.
The above elements β are YSLa, Gd, and Dy.

For example, it is at least one element selected from the group consisting of HOlBr, Tm, Yb and Lu.

More specifically, among the above element combinations, examples of composite oxide materials that have been confirmed to have particularly excellent properties include Y-Ba-Cu-0 series, La-Ba-Cu-0 series, and Examples include La-3r-Cu-0-based composite oxide materials. Specifically, Y+Ba2CuaOt-x, 1lOIBa2cu3
Ch-x, LulBa2Cu30t-x, Sm, Ba
2(:u30.,.

Nd1Ba2Cu307-X, Gd+Ba2Cus
O? -x-.

ButBa2Cu3Ch-x, Er l Ba2Cu
30 t-x,DLBa2CuaC)v-xs Tr
nlBa2CusOt-xYbtBaaCus 0t-
x LulBa2Cu3Cat-xs [However,
is a number satisfying Q<x<l].

The oxide is preferably a perovskite-type oxide or a pseudo-perovskite-type oxide.

Incidentally, pseudo-perovskite refers to a structure similar to perovskite, and includes, for example, an oxygen-deficient perovskite type, an orthorhombic type, and the like.

When creating a superconducting wire by applying the method of the present invention, as the raw material powder, (1) a mixture of compound powders of each element constituting the desired composite oxide is used, or (2) a mixture of Compound powder of elements included in group a of the periodic table [compound powder of elements included in group a of the periodic table, group 1b, group mb, group mb, group IVa of the periodic table, group Ia of the periodic table]
It is advantageous to use any of the composite oxide fired powders obtained by firing a mixture of an element included in the group with a compound powder and grinding a composite oxide. In the case of (2), generally the powder of the elements constituting the composite oxide or their oxides, carbonates, etc. is used as the raw material powder, and this raw material powder is used as the atom of each element constituting the desired composite oxide. It can be manufactured by sintering a mixed powder that has been mixed in such a manner as to achieve the desired ratio. Since such a sintered body powder has a composition that effectively affects superconducting properties formed in advance, it can be made into a product of uniform material after being sintered into a wire rod.

Furthermore, from this point of view, it is preferable to repeat the firing-grinding process multiple times to homogenize and refine the raw material powder.

The heating temperature during firing or sintering using these raw material powders is generally a temperature of 600° C. or higher, with the upper limit being the melting point of the compound with the lowest melting point among the compounds contained in the raw material powders. That is, if the sintering temperature exceeds this range, a solid solution phase will occur in the sintered body, and a sintered body that exhibits effective superconducting properties will not be formed.

On the other hand, at temperatures below the above range, the sintering reaction is insufficient and a composite oxide is difficult to form.

The above sintering conditions vary depending on the type of composite oxide used and the type of metal cylinder;
Cus 07-X [However, Ln is YSLaSGd, DySHaSErS
Represents at least one element selected from the group consisting of Tm, Yb and Lu. ] In the case of , the following conditions can be cited as preferred ranges. : Metal cylinder material Sintering conditions A1 550-620°C 15-25 hours Cu
750-820℃ 10-20 hours Ni
700-770℃ 10-20 hours Ag
900 to 960°C for 10 to 20 hours. Especially preferred sintering conditions are [600°C/20 hours] in the case of AI.
, Cu [800°C, 15 hours], Nl [750°C/15 hours], Ag [940°C/1
5 hours], etc. Furthermore, in order to form a preferable crystal structure of the composite oxide sintered body, which is a superconducting material, it is preferable to use a cylinder made of Ag, which is easily permeable to oxygen.

The sintering process is performed under optimal conditions depending on the type of powder raw material used.
That is, the sintering temperature and time are determined. For example, in the case of a composite oxide superconducting material, the sintering temperature is generally 700° C. or higher, with the upper limit being the melting point of the compound with the lowest melting point among the compounds contained in the raw material powder. That is, if the sintering temperature exceeds this range, a solid solution phase will occur in the sintered body, and a sintered body that exhibits effective superconducting properties will not be formed. On the other hand, at temperatures below the above range, the sintering reaction is insufficient.
Complex oxides are less likely to be formed.

It is generally preferred that the cooling step be carried out slowly.

In particular, the cooling rate for composite oxide superconducting materials is 1°C.
The temperature range is preferably from 0.01° C./sec to 0.01° C./sec.

The reason for this is that when the cooling rate is 1° C./second or more, the cooling rate of the method according to the present invention is too rapid, and crystal orientation is not formed. On the other hand, the slower the cooling rate, the more preferable it is, but if it is 0.01° C./sec or less, the cooling takes too much time and is no longer an industrially advantageous method.

Furthermore, in addition to the above-mentioned systems, the present invention also provides the following general formula;
8, p is p = (6+2m+2n) / 2, q is a number that satisfies 0<q<1, and r is a number that satisfies -2≦r≦2]. It can also be applied to composite oxide superconductors mainly having the composition shown above.

More specifically, the following composite oxide superconducting materials may be mentioned.

B14Ca4Sr4CU602o-y (B12Ca2
Sr2CU301G-Y)T]4Ca4Ba4CUsO
2o-y (T12Ca2Ba2Cu3010-Y) [
Here, y is +2≧y≧−2] The present invention will be described in more detail below according to examples, but the technical scope of the present invention is not limited by the following disclosure.

Example BaCC1+, Y2O3 and C with a purity of 99.9% or more
Each powder of uO was prepared and weighed so that Y2O3 powder was 20.8% by weight, BaCO3 powder was 54.7% by weight, and CuO powder was 24.5% by weight, and after wet mixing with an attritor, 110% It was dried for 1 hour at ℃. This mixed powder was press-molded at a pressure of 100 kg/c++f to form 94
After baking at 0° C. for 15 hours, it was ground to 100 meshes or less.

Thereafter, the process of molding, firing, and pulverization was repeated three times in the same manner, and then the obtained fired powder was filled into a 20 mm diameter Ag pipe, both ends of which were sealed, and then reduced to a diameter of 5 mm. The wire rod thus obtained (sample No.

The raw material powders were sintered by heating 1 to 4) at a heating temperature of 950°C. After the sintering was completed, the wire was cooled at a cooling rate of 10° C./min to obtain a superconducting wire. Note that Table 1 shows the start time of applying the magnetic field to each wire and the applied magnetic field strength. Further, the magnetic field was applied in a direction parallel to the axial direction of the wire using a hollow coil.

Each sample thus obtained was evaluated by measuring the superconducting critical current density. The critical current density was determined by dividing the current value immediately before electrical resistance occurs in the sample by the area of the current path using a four-terminal method.

Table 1 As can be seen from Table 1, in Samples 3 and 4 treated in a magnetic field according to the method of the present invention, the critical current density of the sintered wire rods is improved.

Effects of the Invention As detailed above, according to the present invention, various elongated sintered products can be manufactured while maintaining high quality, especially in terms of density.

That is, according to the method of the present invention, by filling raw material powder into a metal cylindrical body and processing it, a long body of any diameter and length can be obtained by mixing an organic adhesive or the like into the raw material powder. In addition, by applying a magnetic field during the manufacturing process, the orientation of the sintered body can be improved.

The method according to the present invention can be applied to all anisotropic sintered bodies, and especially when applied to the production of wires using composite oxide superconducting materials, The critical current density can be significantly improved.

In addition, in the method of the present invention, it is also possible to manufacture a long body having any cross-sectional shape, including a hollow body, by storing a core of an appropriate shape in the cylinder in advance together with the raw material powder. .

Patent applicant: Sumitomo Electric Industries, Ltd.

Claims (1)

[Claims] A step of filling raw material powder into the inside of a metal cylinder suitable for plastic working, a step of plastic working the cylinder containing the raw material powder, and a step of filling the cylinder containing the raw material powder. In a method for manufacturing a long sintered product, the method includes a step of heating and firing or sintering the raw material powder, and a step of cooling a cylinder containing the fired or sintered raw material powder. A method characterized in that, after the step of firing or sintering the powder, any or all of the above steps are performed in a magnetic field.