JPH0340982A - Tube bundle and its production - Google Patents

Abstract

PURPOSE:To obtain the tube bundle having excellent dimensional precision with high productivity by joining plural sintered-body tubes drawn by superplastic working. CONSTITUTION:Various ceramics can be used as the sintered body. For example, the raw material power of a calcium phosphate-based ceramic such as apatite and tricalcium phosphate is formed into a tube, and the tube is sintered to obtain a sintered body exhibiting superplasticity. The grain size of the sintered body is preferably controlled into <=10mum to develop superplasticity. The sintered body is drawn by superplastic working into a sintered-body tube having a specified size. Plural sintered tubes are successively or simultaneously bundled in their axial direction or superposed on one another, and the peripheries are joined and integrated. At the time of joining thereof, the superplastic working is used.

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to a tube assembly and a method for manufacturing the same.

<Prior Art> Apatite and calcium phosphate ceramics exclusively made of tricalcium phosphate are used as filling and restorative materials for living bodies, such as artificial tooth roots, dental crowns, artificial bones, and artificial joints.

This is because calcium phosphate ceramics blend well with surrounding living tissues, have high bioactivity and biocompatibility, and are rarely judged as foreign substances by surrounding tissues.
This is because, especially when used in artificial bones, it can promote surrounding remains and firmly connect itself to bone tissue.

In addition, alumina, silicon nitride,
Ceramics such as zirconia are used.

<Problems to be Solved by the Invention> Such calcium phosphate ceramics can be used in various ways in addition to the 4 conventional uses by taking advantage of their high biocompatibility.

One example is a filling material for alveolar ridge formation. Filling with a filling material for alveolar formation is used to prevent teeth from falling out due to periodontal disease or natural resorption of the alveolar ligament, or to prevent teeth from falling out, or when implanting an artificial tooth root. This is done so that the tooth root can be stably implanted, and apatite granules are used as the filling material.

More specifically, apatite granules are wrapped in a water permeable and air insulating sheet such as Voretex, this is placed on the alveolar floor, and the gingiva is sutured. After forming the alveolar ridge, the Voretex is removed and the tooth root is then implanted.

However, conventional treatments have the disadvantage that the granules move after the treatment, which interferes with the formation of the alveolar ligament, and that removal of the Voretex becomes a burden on the patient.

Therefore, if small-diameter apatite tubes are assembled and overlapped to form a mesh-like sheet, alveolar ridge formation can be performed quickly, and the filling material will not move after the procedure. There is no need to remove the.

Further, other examples include adsorbents and filters that utilize biocompatibility, such as carriers for chromatodarum, filters for dialysis machines, and various separation devices.

In order to make such adsorbents or filters, there is a method of making the sintered body itself porous, such as calcium phosphate, but it is difficult to make the sintered body uniformly porous, so it is necessary to precisely form fine pores. It's difficult. In addition, it is extremely difficult to clean 15Il after adsorption with a porous material, making it difficult to reuse it.

On the other hand, as another embodiment of the adsorbent or filter, it is also possible to use the sintered body in the form of a fine hollow tube, for example, by converging it in the axial direction.

However, in these cases, it is almost difficult to create a mold to mold the sintered body into a narrow tube shape.
Furthermore, since the material shrinks due to sintering, it is not possible to form a tube with good dimensional accuracy.

Furthermore, it is extremely difficult to produce adsorbents, filter biomaterials, etc. with good dimensional accuracy by converging or integrating a plurality of tubes.

In addition, conventional plastic working cannot produce fine-diameter tubes with good dimensional accuracy of sintered bodies;
Application to filters, biomaterials, etc. could not be realized.

An object of the present invention is to provide a tube assembly with good dimensional accuracy and excellent mass productivity, and a method for manufacturing the same.

Means for Solving the Problems> These objects are achieved by the present invention as described in (1) to (4) below.

(1) A tube assembly characterized by joining a plurality of sintered tubes stretched by superplastic processing.

(2) The average grain size of the sintered tube is 10
The tube assembly according to (1) above, which is less than μ.

(3) The tube assembly according to (1) or (2) above, wherein the sintered body is a calcium phosphate ceramic.

(4) Manufacturing a tube assembly characterized by comprising the steps of stretching a hollow sintered body by superplastic working to form a sintered tube, and joining the sintered tube by superplastic working. Method.

Effect> The ceramic tube of the present invention is produced by superplastic working.

Ceramics are generally produced by sintering, but
When forming the material, 1. Similar to metal processing, plastic processing such as forging, extrusion, and rolling has also been attempted. but,
Plastic working of ceramics requires high temperatures of about 60% or more of the melting point, reaching as high as 2000°C depending on the material.

However, ceramics exhibit superplasticity.

Journal of the JSTP vol.2
9 no, 32B (1988-3).

As described in Ceramics 24 (1989) No. 2, Iron and Steel Leaf Vol. 75 (1989) No. 3, etc.
It exhibits enormous ductility with low stress at temperatures much lower than the sintering or forging temperatures, for example as low as 500°C.

Typical materials conventionally known as ceramics exhibiting superplasticity are Y-TZP (Yttria-s
tabilized Tetragonal Zr0z
Polycrystals).

It is a Zr02-AI2t O3 system, and extrusion processing, thin plate forming, etc. have been attempted using its plastic deformation.

Further, in the above-mentioned papers, it is reported that a deformation amount of about 1.0 in terms of true strain can be obtained.

In the present invention, by utilizing this superplasticity, a hollow sintered body is repeatedly stretched to form a small diameter tube, which is also joined by superplastic working.

Therefore, the present invention is excellent in mass production, and the dimensional stability of the unit tubes constituting the obtained assembly is also extremely high. This is the first time it has been proven.

Heretofore, there has been no report that calcium phosphate ceramics, which are particularly effective in the present invention, exhibit superplasticity.

When using a calcium phosphate system, the tube assembly of the present invention is useful as a biological material such as the above-mentioned mesh sheet-like filling material for alveolar machine imaging, or as an adsorbent or filter for chromatogram carriers and various filters. .

In addition, other sintered materials can be used as adsorbents, structural materials, heat insulation materials,
It is useful as a fireproof material, etc.

<Specific configuration> Hereinafter, the specific configuration of the present invention will be explained in detail.

The filter of the present invention is made of a sintered body.

Various ceramics can be used as the sintered body.

Under these circumstances, alumina, zirconia, and alumina are ceramics with high chemical stability and biosafety.
Examples include zirconia, silicon nitride, calcium phosphate, cordierite, mullite, and alumina-silicon nitride.

Among these, calcium phosphate ceramics have particularly high bioactivity and affinity, and have excellent substance separation and conversion functions.

Although various types of calcium phosphate ceramics can be used, apatite or tertiary calcium phosphate is particularly preferred.

The stoichiometric composition is Ca+o(PO4)aX2 (where X is a hydroxy group, a halogen atom, or Co), and hydroxyapatite or fluorinated apatite is particularly suitable.

In addition, the Ca/P atomic ratio of apatite is 1.6 to 1.
75 is preferred.

In addition, similar to these apatites, tertiary calcium phosphate C
Also preferred is ax(PO4)2.

These sintered bodies may contain a sintering aid, etc., and in the case of calcium phosphate ceramics, 70% by weight of the total
Within the following range, Al2203. S i O2, Mg
O, furthermore, CaO, etc. may be contained.

The average grain size of the sintered body such as phosphoric acid ceramics constituting the tube of the filter of the present invention is 10- or less,
In particular, it is preferably 2- or less.

The average grain size may be measured using a scanning electron microscope. Specifically, from the average grain area, assuming that this is a circle, the average diameter is determined, and this is determined as the average grain size.

In this case, if the average grain size exceeds 10 -, superplasticity will be insufficiently expressed.

Note that the average grain size is 1 μs or less, especially 0.7-
It is preferably below, and the lower limit is generally 0.00
It is preferable that it is about 5-.

The average grain size of such a sintered body tube is approximately maintained even by the superplastic working described below, so the average grain size of the sintered body before stretching is approximately the same as that of the tube.

However, since the sintered tube of the present invention is generally stretched by uniaxial stress, deformation of the grains and orientation between the grains are usually observed.

The sintered tube of the present invention has -M, an inner diameter of 0, OO
It is about OO2 to 50 mm.

In this case, for biomaterials, adsorbents, or mesh sheets, the diameter is 0.001 to 50 mm, especially 0.005 to 5 mm.
mm, filters for separating or removing platelets, hemoglobin, white blood cells, red blood cells, etc. are O,0OO02~0.
The length should be approximately 0001mm.

Further, the wall thickness is generally approximately o,ooot to 20+mm.

In this case, the biological material or adsorbent has a thickness of 0.001 to 20 mm, and the platelet filter has a thickness of about 0.0OO1-0.1 nm.

And its length is arbitrary.

In this diameter range, according to the present invention, a tube with extremely high dimensional accuracy is realized.

As shown in FIG. 1, a plurality of such sintered tubes 1 are bundled in the axial direction and joined together on their circumferential surfaces to form a tube assembly 2, which is used as an adsorbent or the like.

Alternatively, as shown in FIG. 2, the tubes 1 are stacked one on top of the other, and a plurality of layers are stacked with gaps between them, and the tubes are assembled into a mesh sheet or a porous sheet to form the tube assembly 2. In this case, the porosity is
5 to 95%, especially 20 to 95% as a filling material for alveolar implants
About 50% is preferable.

In this way, by using hollow tubes with a diameter of about 0.001 to 0.1 mm, and with the above-mentioned pore size, especially between the tubes.
．． By laminating and integrally fixing the materials with a gap of 0.3 to 0.5 mm, it can be used as a filling material for alveolar machine implantation and can be freely filled according to the shape of the alveolar ridge, which simplifies the treatment.

In this case, the thickness of the sheet is preferably about 0.05 to 1 mm.

In addition, in these, the number of tubes to be used may be determined depending on the application.

Such a sintered tube is manufactured as follows.

First, a sintered body with a predetermined grain size is produced. The sintered body is preferably a tubular hollow body, the average grain size of which is 10 to 10
It shall be approximately 0%.

There are no restrictions on the raw materials used to produce the sintered body.
It may be determined appropriately depending on the material of the sintered body.

In the case of calcium phosphate ceramics, the aforementioned apatite or tertiary calcium phosphate is used.

These may be natural products recovered from the bones and teeth of various vertebrates, and each f! It may be a synthetic product manufactured by a wet method or a dry method.

In the present invention, a raw material powder such as apatite or tertiary calcium phosphate is sintered to obtain a sintered body exhibiting superplasticity.

The raw material powder used preferably has a BET value of about 1 to 300 m27 g.

Note that, as described above, these may contain a sintering aid or the like.

Next, this raw material powder is molded into a tube shape.

When molding, after uniaxial pressing at about 1 to 3000 kg/cm", 1000 to 10000 kg/c+n
``Cold isostatic pressing (CIP) may be performed.

After this, it is sintered.

Sintering may be performed under known conditions depending on the material, but in the case of calcium phosphate ceramics, it is generally
It is carried out at 00 to 1200°C for about 0.05 to 30 hours.
During firing, hot pressing or hot isostatic pressing (HIP) is preferably performed to densify the material, and the pressure is preferably about 50 to 5000 atm. Further, the atmosphere may be inert gas, air, hydrogen, vacuum, or the like.

Note that during this firing, calcination may be performed, and in the case of calcium phosphate ceramics, the firing temperature is 700 to 1350.
Calcination may be performed at a temperature of about 0.05°C for about 0.05 to 30 hours.

In this way, a sintered body is obtained which preferably has a relative density of 99% or more, in particular 99.5% or more, and has the above-mentioned average grain size.

By setting the average grain size of the sintered body to a predetermined value or less, superplastic working becomes possible.

Note that this sintered body generally has an inner diameter of 0.1 to 100 mm.
, with a wall thickness of 0.1 to 20 mm and a height of approximately 50 to 500 mm.

Next, this tube-shaped sintered body is subjected to superplastic processing.

Although the processing temperature can be varied depending on the material, it is generally performed at a temperature of 600° C. or higher and 50° C. lower than the sintering temperature. In the case of calcium phosphate ceramics, the temperature is generally preferably 600 to 1200°C.

At a tensile rate of about 0.01 to 50 mm/min, a tensile stress of l to 70 MPa is obtained, and the amount of deformation is about 0.1 to 1.5 in true strain.

By repeating this superplastic working several times as necessary, a tube of predetermined dimensions can be obtained.

In this case, the final stretching ratio is 0.1-1.
It is preferable to set it to about 5.

Note that the stretching may be carried out by pulling both sides of the workpiece, but in addition to this, drawing or extrusion may also be used.

Variations may occur in the grain size of the resulting tube.

However, the grains may slide along the grain boundaries, and the grains may be deformed, causing orientation of the grains to be observed.

The grains may be distorted so as to produce anisotropy of -1 to about 1 to 2.5 major axis/minor axis.

Note that an inorganic filler may be contained within the tube body.

Various fillers may be used, but from the viewpoint of biocompatibility, oxide fillers containing one or more of silica, calcia, alumina, magnesia, and zirconia are preferred.

The filler may be granular or whisker-like.

A plurality of such sintered tubes are arranged and focused in the axial direction, and their circumferential surfaces are joined to be integrally fixed.
Alternatively, they are joined together into a mesh sheet.

For joining, superplastic working is also used, and the above-mentioned working temperature is used. The bonding time is about 1 to 100 minutes.

Further, when bonding, it is preferable to apply a pressure of about 1 to 70 MPa to perform solid phase or diffusion bonding.

Thereby, a bonding strength of about 200 to 1000 MPa can be obtained.

Further, in the present invention, stretching and bonding may be performed simultaneously, or stretching may be performed after bonding, depending on the case.

In this way, the tube assembly of the present invention is obtained.

<Examples> Hereinafter, the present invention will be explained in more detail by presenting specific examples of the present invention.

Example: BET value 80 m27g of hydroxyapatite (Ca/P-=1.67) obtained by the wet method was
After axial pressing at 2900 kg/cm”
kg/c+++'' and made into a CIPL hollow tube body.

Next, this was calcined in the air at 1000''C for 2 hours, and then HIP fired under the conditions of Ar gas, 1000C, 2000atm, and 2 hours.

The obtained tubular hollow body had an inner diameter of 1 mm and a wall thickness of 1 m.
m, and the height was 100 mm. Also, the relative density is 99,
9%, average grain size was 0.64μ.

This tube body was heated to 1000°C with a tensile stress of 60 MP.
a, tensile rate was 1, Olam/min, and the amount of deformation was about 0.5 true strain.

Repeat this 4 times to obtain an inner diameter of 0.05 mm and a wall thickness of 0.0 mm.
A 5n+m sintered tube was obtained.

Note that the average grain size was 1 μs, and deformation and orientation of the grains were observed.

Also, the variation in tube inner diameter and wall thickness is 0.1%.
The dimensions were as follows, and the dimensional accuracy was extremely good.

Next, this sintered tube was cut into 200 mm pieces, and multiple pieces were stacked together as shown in FIG.
a. Bonding was carried out at 1000° C. for 15 minutes to obtain a mesh sheet of the tube assembly of the present invention as shown in FIG.

The thickness of the mesh sheet was 0.2 mm, and the transverse tube gap was approximately 0.1 mm.

However, the joint strength between the tubes was sufficient.

This material could be well handled as a filling material for alveolar imaging.

Example 2 In Example 1, the sintered body was changed to Y-TZP, the processing temperature was changed to 1450°C, and a plurality of tubes were formed, which were converged in the axial direction and joined, resulting in a tube with an inner diameter of 5 mm. A tube assembly as shown in FIG. 1 was produced.

<Effects of the Invention> According to the present invention, a tube assembly with extremely high dimensional accuracy can be manufactured from a sintered body with high mass productivity.

[Brief explanation of drawings]

FIG. 1 and FIG. 2 are front views showing different examples of the tube assembly of the present invention, respectively. Explanation of symbols l... Sintered tube 2... Tube assembly

Claims (4)

[Claims] (1) A tube assembly characterized by joining a plurality of sintered tubes stretched by superplastic processing. (2) The average grain size of the sintered tube is 10
The tube assembly according to claim 1, which has a diameter of μm or less. (3) The tube assembly according to claim 1 or 2, wherein the sintered body is a calcium phosphate ceramic. (4) Manufacture of a tube assembly characterized by comprising a step of stretching a hollow sintered body by superplastic processing to form a sintered tube, and a step of joining the sintered tube by superplastic processing. Method.