JP2001019569A - Porous calcium phosphate-based compound/metal composite sintered compact and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a composite sintered compact of porous calcium phosphate- based compound grains and a metal having excellent biocompatibility and a high strength without causing the falling off of the porous calcium phosphate- based compound grains from the surface and to provide a method for producing the composite sintered compact. SOLUTION: This composite sintered compact of porous calcium phosphate- based compound grains 13 and a metal in which a part of the porous calcium phosphate-based compound grains 13 are protruded from the surface is produced by prebaking the calcium phosphate-based compound grains 13 at a sintering starting temperature or above, thereby preparing a porous calcium phosphate- based compound powder, preparing a powder to be sintered from the porous calcium phosphate-based compound powder and a metal powder 14 so that the porous calcium phosphate-based compound powder 13 is present in at least a part of the surface layer and a part thereof is protruded from the surface and sintering the powder to be sintered under pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a porous calcium phosphate compound particle / metal composite sintered body having a structure in which porous calcium phosphate compound particles having high biocompatibility protrude from the surface, and such composite sintered body. A method for producing a body in a short time and at low cost.

[0002]

2. Description of the Related Art Calcium phosphate compounds (for example, hydroxyapatite) have excellent biocompatibility and are used as biomaterials such as artificial dental roots, bone reinforcing materials, and dental cement. However, calcium phosphate compounds are inferior in mechanical strength, particularly in bending strength, and cannot be used for parts requiring high strength. Therefore, the artificial tooth root, the bone reinforcing material, and the like are formed of a metal material having no harm to humans, such as titanium or stainless steel. However, from the viewpoint of biocompatibility, calcium phosphate compounds are far superior, and it is desired to use calcium phosphate compounds, especially hydroxyapatite.

Under the circumstances described above, attempts have been made to combine a calcium phosphate compound with a glass material or a metal material, and some of them have already been put into practical use. However, in the case of composite with a glass material, there is a problem that glass elutes in a living body over time.

A composite material of a calcium phosphate compound and a metal material is generally obtained by embedding calcium phosphate compound particles in a metal frame or sintering a mixture of a metal powder and a calcium phosphate compound powder. Can be However, in the former case, there is a possibility that the displacement of the calcium phosphate compound may occur in the living body. In the latter case, the calcium phosphate-based compound powder has a low porosity and a small particle size, and thus has a disadvantage that the calcium phosphate-based compound particles exposed on the surface of the composite sintered body easily fall off. Further, in the conventional composite material, even the calcium phosphate compound particles exposed on the surface are almost completely buried in the metal matrix. Therefore, there is a disadvantage that the biocompatibility of the calcium phosphate compound is not sufficiently utilized.

Accordingly, an object of the present invention is to provide a composite sintered body of porous calcium phosphate compound particles and a metal,
A composite sintered body having excellent biocompatibility, which has never been seen before because part of the calcium phosphate compound particles protrude from the surface, and preventing the calcium phosphate compound particles from falling off from the surface; It is an object of the present invention to provide a method for manufacturing a compact in a short time and at low cost.

[0006]

Means for Solving the Problems In view of the above problems, as a result of intensive studies, the present inventors have found that when a calcium phosphate compound powder / metal composite is pressure-sintered, it is sintered as a calcium phosphate compound powder. Using a porous calcium phosphate compound powder pre-fired at a temperature equal to or higher than the setting start temperature, and a porous calcium phosphate compound powder such that at least a portion of the porous calcium phosphate compound powder protrudes from the surface. By providing a non-sinterable powder layer on the outside of the steel, it was discovered that a composite sintered body having a structure protruding from the surface so that the porous calcium phosphate compound particles did not fall off was obtained, and the present invention was completed. .

That is, the composite sintered body of the porous calcium phosphate compound particles and the metal of the present invention has a surface layer containing the porous calcium phosphate compound particles on at least a part of the surface thereof, It is characterized in that a part of the compound particles protrude from the surface.

A preferred example of the composite sintered body of the present invention comprises a surface layer composed of porous calcium phosphate compound particles and a metal, and an inner layer composed essentially of only a metal.
The ratio (area ratio) of (total exposed area of porous calcium phosphate-based compound particles) / (surface area of surface layer containing porous calcium phosphate-based compound particles) is preferably 5 to 70%. Further, among the porous calcium phosphate-based compound particles protruding from the surface, the height of the protruding portion is preferably not more than half of the particle size.

The porous calcium phosphate compound particles contained in the composite sintered body have an average particle size of 0.5 to 10 mm and 20 to 70%
It is preferable to have a porosity of The pores of the porous calcium phosphate compound particles are preferably of a size such that the metal has at least partially penetrated therein, so that the porous calcium phosphate compound particles are firmly bonded to the metal phase. .

The metal used for the composite sintered body of the present invention includes Ti, Cr, Fe, Co, Cu, Mo, Ag, Au, Pd, Pt, Al and
It is preferably a metal selected from the group consisting of Ni or an alloy thereof. The weight ratio of the porous calcium phosphate compound particles to the metal in the surface layer is preferably 1/20 to 1/4.

The method for producing a composite sintered body of porous calcium phosphate compound particles and a metal according to the present invention is characterized in that the calcium phosphate compound powder is pre-fired at a temperature not lower than the sintering start temperature. A compound powder is prepared, and the porous calcium phosphate compound powder and the metal powder are combined so that the porous calcium phosphate compound powder is present on at least a part of the surface, and the porous calcium phosphate compound powder is mixed. It is characterized in that the outside of the body is covered with a flexible layer made of powder that does not sinter at the sintering temperature of the composite sintered body, and is sintered under pressure.

In the method of the present invention, it is preferable that the calcium phosphate-based compound powder has a preliminary firing temperature of 700 to 1300 ° C. It is preferable to use a spark plasma sintering method as the pressure sintering method. Preferably, the sintering temperature is 500 to 1300 ° C., and the time for maintaining the sintering temperature is 5 to 30 minutes.

The powder that is not sintered at the sintering temperature of the composite sintered body of the present invention is preferably a ceramic powder having a melting point higher than that of a metal powder. It is preferably at least one selected from the group consisting of powder, carbon powder, alumina powder, zirconia powder, boron nitride powder, and silicon nitride powder.

The porous calcium phosphate compound powder used for producing the composite sintered body of the present invention has an average particle size of 0.5 to 10 mm and a porosity of 20 to 70%, and its pores are contained therein. It is preferable that the size is such that the metal at least partially enters and the porous calcium phosphate compound particles are firmly bonded to the metal phase. The metal powder is 1-500 μm
It is preferred to have an average particle size of

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The composite sintered body of the present invention comprising porous calcium phosphate compound particles and a metal and a method for producing the same will be described in detail below.

[1] Method for Producing Composite Sintered Body (A) Production of Porous Calcium Phosphate Compound Powder (1) Production of Expanded Calcium Phosphate Compound Powder To produce a porous calcium phosphate compound powder,
First, porous granules of calcium phosphate compound powder are produced. Calcium phosphate compounds that can be used in the present invention
The molar ratio of Ca / P is 1.5 to 2.0, specifically, apatites such as hydroxyapatite and fluorapatite, tricalcium phosphate, tetracalcium phosphate and the like, or a mixture of two or more thereof.

The granules can be produced by a known method, but it is preferable to use a method described in JP-A-3-252304, a spray-dry granulation method, or the like. The method for producing granules described in JP-A-3-252304 is to thicken or gel after foaming a slurry or a flowable gel containing a calcium phosphate compound powder and a polymer substance, and forming the resulting foam molded article. If necessary, calcine and pulverize, or after thickening or gelling a slurry or a fluid gel containing a calcium phosphate compound powder, a polymer substance and a foaming agent, and foaming by heating, It is a method of calcining and pulverizing accordingly. Hereinafter, each will be described in detail.

Method A polymer having a mean particle size of 1 to 50 is added to a dispersion liquid (which may be a solution, a colloid solution or a suspension) or a fluid gel.
A calcium phosphate-based compound powder of μm is mixed and vigorously stirred to embrace air to obtain a slurry or a fluid gel containing many fine bubbles. The size and amount of bubbles in the foamed slurry or fluid gel can be controlled by stirring. The solid content concentration of the slurry or the fluid gel is 7 to 65% by weight of the calcium phosphate compound powder and 100% by weight, assuming that the whole is 100% by weight.
It is preferably from 1 to 10% by weight. The foamed slurry or fluid gel is poured into a mold and dried. Thus, a high-strength foam molded article having substantially spherical cells can be obtained.

The dispersion or fluid gel of the polymer substance may be stirred and foamed before mixing with the calcium phosphate compound powder, or the powdery polymer substance and the calcium phosphate compound powder may be mixed. After mixing, a dispersion medium may be added to form a slurry, which may be stirred and foamed.

Since water is generally used as a dispersion medium for the calcium phosphate compound powder, the polymer substance is preferably water-soluble, but when an organic solvent is used, it is dissolved in the solvent. You may. Examples of such high molecular substances include cellulose derivatives such as methylcellulose and carboxymethylcellulose, polysaccharides such as curdlan, and polymers such as polyvinyl alcohol, polyacrylic acid, polyacrylamide, and polyvinylpyrrolidone.

Method This method is the same as the method, except that a blowing agent is used instead of air entrapment. Therefore, the calcium phosphate compound powder and the polymer used in this method are as described above.

The calcium phosphate compound powder, a foaming agent and a polymer substance are kneaded in a dispersion medium to form a slurry or a fluid gel. As the foaming agent, hydrogen peroxide, ovalbumin and the like are used. A desired porosity can be obtained by changing the concentration or the amount of the foaming agent. For example, when using hydrogen peroxide alone, the hydrogen peroxide is 0.01 to 0.
It is sufficient to add it to be present in an amount of 5% by weight.

The amount of the polymer substance used in this method may be smaller than that in the above method, and may be about 0.0001 to 2.0% by weight based on 100% by weight of the whole slurry or fluid gel.
For example, in the case of methylcellulose, it may be 0.001 to 1.5% by weight, and in the case of polyvinyl alcohol (molecular weight 2000)
~ 0.3% by weight, for polyacrylic acid 0.0001 ~ 0.
001% by weight, pectin 0.005 to 0.1% by weight
Is good.

The obtained slurry or fluid gel is mixed with 70 to 12
Heat to 0 ° C and dry with foaming. In the early stage of the heating step, foaming occurs, and the bubbles are embraced in the thickened slurry as they are, so that a plurality of bubbles do not combine or be released. Therefore, a foam molded article in which fine bubbles are uniformly dispersed can be obtained.

(2) Pre-firing In order to prevent sintering from substantially proceeding during discharge plasma sintering, pre-firing is performed on the foamed molded product of the calcium phosphate compound. For this purpose, the pre-firing temperature must be equal to or higher than the sintering start temperature. In a preferred embodiment, the pre-firing temperature is between 700 and 1300 ° C. If the pre-sintering temperature is lower than 700 ° C, sintering of the calcium phosphate compound granules occurs during pressure sintering, and the crystal grains are coarsened, deformed by pressure, the pores are collapsed, and the porosity is lost, The metal does not sufficiently enter the pores.
If the temperature is higher than 1300 ° C., decomposition or deterioration of the calcium phosphate compound occurs, which is not preferable. The preferred pre-firing temperature is 700-1200 ° C.

The pre-firing time (time at which the pre-firing temperature is maintained) is preferably 1 to 10 hours. If the pre-firing time is less than 1 hour, the pre-firing effect cannot be obtained, and
There is no change in the effect even if the firing is performed for a longer time, and the cost increases. A more preferred pre-firing time is 2 to 5 hours.

The atmosphere for the preliminary firing is not particularly limited,
In order to prevent the decomposition of calcium phosphate compounds,
It is preferably performed in the atmosphere.

It is preferable that the block of the porous calcium phosphate compound obtained by the preliminary firing is pulverized and then classified to adjust the particle size to 0.5 to 10 mm. If the particle size of the porous calcium phosphate compound powder (granules) is smaller than 0.5 mm, the surface exposed area of the porous calcium phosphate compound particles and the proportion of the calcium phosphate compound particles protruding from the surface are insufficient, and the ratio is less than 10 mm. If it is too large, the distribution of the porous calcium phosphate compound particles in the composite sintered body becomes uneven, and the possibility of crushing of the porous calcium phosphate compound particles protruding from the surface increases, which is not preferable. The more preferred particle size of the porous calcium phosphate compound powder is 1 to 5 mm.

The calcium phosphate compound powder of the present invention has a porous structure in consideration of the bonding property with bone and the like.
Porosity of porous calcium phosphate compound powder is 20 ~ 70
%. If the porosity is less than 20%, the metal does not sufficiently enter the pores of the porous calcium phosphate compound particles, resulting in poor adhesion. On the other hand, when the porosity exceeds 70%, the mechanical strength of the porous calcium phosphate compound powder itself becomes insufficient, which is not preferable. Although the pores vary in size, it is necessary to have pores large enough to allow metal to enter by at least pressure sintering.
It preferably has a diameter of 00 μm. The porous calcium phosphate-based compound particles having such a structure are firmly adhered to the metal phase by the metal entering the pores, and therefore do not fall off even if a part of the particles protrudes from the surface.

(B) Production of Powder to be Sintered The powder to be sintered consisting of a porous calcium phosphate compound powder and a metal powder to be sintered under pressure may be a homogeneous mixture, but has good biocompatibility and mechanical properties. In order to simultaneously obtain the mechanical strength, a surface layer containing a porous calcium phosphate compound powder is provided on at least a part of the surface, and a part of the porous calcium phosphate compound powder is protruded from the surface, and other parts are formed. It is preferable to form only with metal powder.

As the metal powder, Ti, Cr, Fe, Co, Cu,
Mo, Ag, Au, Pd, Pt, preferably a metal selected from the group consisting of Al and Ni or an alloy thereof, particularly Ti, Fe, Pd
Or an alloy thereof is more preferable. Stainless steel is preferred as the alloy. The metal powder preferably has an average particle size of 1 to 500 μm. The average particle size of the metal powder is 50
If it exceeds 0 μm, the relative density of the mixture with the porous calcium phosphate compound powder is too low, and the porous calcium phosphate compound powder does not sufficiently enter the pores. Although the lower limit of the average particle size of the metal powder is not particularly limited,
If it is less than the above, the cost is increased and the filling property is also deteriorated, so that the effect cannot be improved.

For example, in order to form a powder having a sandwich structure having a surface layer containing a porous calcium phosphate compound powder on both sides, first, the porous calcium phosphate compound powder is placed in a cavity of a mold. Then, a metal powder may be added, and finally, a porous calcium phosphate compound powder may be added. Since the metal powder is finer than the porous calcium phosphate-based compound powder, the metal powder enters between the particles of the porous calcium phosphate-based compound powder, and the mixed layer of the porous calcium phosphate-based compound powder and the metal powder (Surface layer)] / metal powder layer (inner layer) / [mixed layer of porous calcium phosphate compound powder + metal powder (surface layer)]
Becomes

(C) In order to protrude a part of the porous calcium phosphate compound powder from the surface of the non-sinterable powder layer, the sintering temperature of the composite sintered body is set outside the porous calcium phosphate compound powder. Then, a flexible layer made of a powder not sintered (non-sinterable powder) is provided. For this purpose, for example, non-sinterable powder layer / [mixed layer of porous calcium phosphate compound powder + metal powder (surface layer)] / metal powder layer (inner layer) / [porous calcium phosphate compound powder Mixed layer (surface layer) of powder + metal powder] / non-sinterable powder layer.

As the non-sinterable powder, a ceramic powder that does not sinter at the sintering temperature of the composite sintered body is preferable. Specifically, a dense pre-fired powder of a calcium phosphate compound such as hydroxyapatite, or a carbon powder , Alumina powder, zirconia powder, boron nitride powder, silicon nitride powder and the like. Although the non-sinterable powder is removed after the completion of the composite sintered body, it is preferable to use a dense pre-fired powder of a calcium phosphate compound such as hydroxyapatite in consideration of the effect on the living body. The precalcination temperature of the dense precalcined powder of the calcium phosphate compound such as hydroxyapatite may be the same as the precalcination temperature of the porous calcium phosphate compound powder.

The non-sinterable powder is preferably not porous so as not to adhere to the metal powder by sintering. The particle size is preferably 1 to 100 μm, and 10 to 80 μm.
m is more preferable. When the particle size of the non-sinterable powder is smaller than 1 μm. Manufacturing, especially classification, becomes difficult and costs increase. If it exceeds 100 μm, it becomes difficult for the porous calcium phosphate compound powder to penetrate into the non-sinterable powder layer, so that the desired projection rate of the porous calcium phosphate compound particles cannot be obtained. Molten metal may enter the layer. In addition, the non-sinterable powder can be densely packed and the pressing force is evenly distributed.
Preferably, the particles are spherical particles.

(D) Pressure Sintering In the present invention, it is preferable to use a spark plasma sintering method for producing a composite sintered body. Spark plasma sintering is a method in which a powder to be sintered is filled between a pair of dies connected to a power supply, and a current is applied while pressurizing. Since the powder to be sintered filled in the mold is in contact with the powder and has many voids between the particles of the powder to be sintered, the calcium phosphate compound is semiconductive, and the metal powder is conductive. When a voltage is applied to both ends of the mold, a current flows through the powder to be sintered. At this time, sparks occur in the gaps between the particles of the powder to be sintered, and discharge plasma is generated in a vacuum. Therefore, the powder to be sintered comprising the porous calcium phosphate compound powder and the metal powder is rapidly sintered. As described above, the spark plasma sintering method produces a composite sintered body by utilizing self-heating caused by a discharge phenomenon between particles, and is capable of producing a high-quality sintered body having excellent thermal efficiency.

An apparatus for performing spark plasma sintering and an example of a spark plasma sintering method using the same will be described with reference to FIGS. A discharge plasma sintering apparatus 1 shown in FIG. 1 includes a vacuum chamber 6 provided with a vacuum pump 7, a mold 2 disposed therein, and a mold 2 which is moved up and down in the mold 2.
Punches 4a and 4b for pressing the non-sinterable powder 12a / sintered powder 3 / non-sinterable powder 12b filled therein, and the punches 4a and 4b
And rams 5a and 5b for driving. A thermocouple (not shown) for measuring a sintering temperature is provided in the molding die 2.

The rams 5a and 5b are driven by a pressure drive mechanism 9 to pressurize the powder 3 to be sintered through the non-sinterable powder layers 12a and 12b on both sides and to feed power terminals (not shown). ) Is connected to the power supply 8 to apply a pulse voltage to the punches 4a and 4b. The pulse voltage is preferably DC. The control unit 10 includes a pressure driving mechanism 9, a power supply 8, a vacuum pump 7,
And a thermocouple for controlling the sintering pressure and temperature in the mold 2, the degree of vacuum in the vacuum chamber 6, and the like.

FIG. 2 is an enlarged view showing details of the mold 2 and the punches 4a and 4b to be loaded in the spark plasma sintering apparatus 1. The molding die 2 has a ring-shaped integral structure, and has a cavity 2a having a cylindrical, oval, rectangular or other cross section. From the viewpoint of conductivity, the mold 2 is preferably formed of a conductive material such as carbon, various metals, and a cemented carbide, and among them, carbon is preferable because of low cost.

It is preferable to provide conductive carbon paper 11 on the inner peripheral surface of the mold 2. The carbon paper 11 serves as a cushioning material for preventing the sintered body from sticking to the inner wall surface of the molding die 2 and also prevents a resistance from being generated when a voltage is applied to the powder 3 to be sintered. Note that carbon may adhere to the surface of the sintered body after sintering, but can be easily removed by heating in the air, so that there is no influence of carbon on the sintered body.

Each punch 4a, 4b is a cavity of the mold 2.
It has the same slightly smaller cross-sectional shape as the cavity 2a so as to move up and down in the interior 2a. Each punch 4a, 4b is a ram 5a,
Since it is fixed to 5b and has a function of applying a pulse voltage to the powder 3 to be sintered, it is preferably formed of a conductive material such as carbon similarly to the molding die 2. Also each punch 4
It is preferable to provide carbon paper 11 also on the outer peripheral surfaces of a and 4b.

In the example shown in FIG. 3, first, the inner surface of the molding die 2 is covered with carbon paper 11 in a state where each part is disassembled, and the lower punch 4b is inserted into the molding die 2, and then the non-sintering is formed in the cavity 2a. A binding powder layer 12b is provided, and then a porous calcium phosphate compound powder 13, a metal powder 14, and a porous calcium phosphate compound powder 13 are sequentially filled to form a layer of the powder 3 to be sintered having a sandwich structure. A non-sinterable powder layer 12a is further provided thereon.

As described above, when the porous calcium phosphate compound powder 13 is contained on both surfaces of the powder 3 to be sintered, the particle size of the porous calcium phosphate compound powder 13 is much larger than the particle size of the metal powder 14. Therefore, the metal powder 14 enters between the porous calcium phosphate compound powders 13 to form a surface layer composed of the porous calcium phosphate compound powder 13 and the metal powder 14. Further, by adjusting the particle size, porosity and pore size of the porous calcium phosphate compound powder 13 and the particle size of the metal powder 14, the porous calcium phosphate compound particles 13 ′ exposed on the surface of the composite sintered body can be formed. It can be 5 to 70 area%.

Since the non-sinterable powder layers 12a and 12b have a high relative density and strength, and are made of a powder that does not form a green compact and have flexibility, the porous calcium phosphate existing on the surface of the powder 3 to be sintered can be used. Part of the system compound powder 13 enters into it.
Since the non-sinterable powder layers 12a and 12b are dense and have few pores and are preliminarily fired, they do not sinter at a prefiring temperature. Therefore, the non-sinterable powder can be easily removed from the composite sintered body obtained after the pressure sintering because it does not strongly bind to the porous calcium phosphate compound powder 13 and the metal powder. In this manner, a composite sintered body having a structure in which the portion of the porous calcium phosphate compound powder 13 that has entered the non-sinterable powder layers 12a and 12b protrudes from the surface is obtained.

After filling, the vacuum chamber 6 is sealed, degassed by the vacuum pump 7, and maintained at a vacuum of about 10 ^-2 Torr. By keeping the inside of the mold 2 in a vacuum state, discharge plasma is generated by application of a pulse voltage.

The pressure drive mechanism 9 is operated by the control unit 10,
At least one of the rams 5a, 5b moves in a direction approaching each other, and the punches 4a, 4b fixed thereto pressurize the powder 3 to be sintered. Pressing force by punches 4a and 4b is 100-2000kgf /
cm ² is preferable, and 200 to 700 kgf / cm ² is more preferable.
Pressure is difficult to 100 kgf / cm ² less than the densification of the sintered body, also 2,000 kgf / cm be larger than ² improve densification effect corresponding thereto is not obtained, insufficient strength of the mold 2 Only the problem described above occurs.

When a pulse voltage is applied between the punches 4a and 4b from the power supply 8, a current flows through the powder 3 to be sintered between the punches 4a and 4b, and the porous calcium phosphate compound powder
Sparks are generated in the gaps between the metal powder 13 and the metal powder 14 to generate heat and generate discharge plasma. By these actions, the porous calcium phosphate compound powder 13 and the metal powder 14
Is heated under pressure and reaches the sintering temperature in about 5 to 20 minutes.

The powder to be sintered 3 is heated according to a preset temperature raising program. For this purpose, the temperature of the powder 3 to be sintered is detected by a thermocouple (not shown) provided in the molding die 2, and the output of the thermocouple is input to the control unit 10. The control unit 10 generates a signal for raising the temperature according to the temperature raising program based on the input temperature data, and outputs the signal to the power supply 8. The power supply 8 supplies an appropriate pulse voltage to the rams 5a and 5b in accordance with a command from the control unit 10.

A preferable pulse voltage has an ON / OFF pattern of a DC voltage, and the ratio (t ₁ / t ₀ ) of the duration t _{1 of one} ON state to the duration t ₀ of _one OFF state is 1 /.
1 to 12/1, for example, 6/1. When t ₁ / t ₀ is smaller than 1/1, heat generation is insufficient and the sintering time is prolonged. When t ₁ / t ₀ is larger than 12/1, the pulse property is reduced and the energy efficiency is reduced. The pulse voltage can be adjusted to a precision of several volts, and the pulse frequency can be adjusted from 300 Hz to 30 kHz. The voltage and frequency of the pulse are adjusted by the control unit 10 so that the powder 3 to be sintered has a predetermined temperature.

The sintering temperature is preferably from 500 to 1300 ° C., more preferably from 800 to 1200 ° C. If the sintering temperature is lower than 500 ° C., sufficient sintering does not occur, and the strength and toughness of the obtained composite sintered body are insufficient. On the other hand, sintering temperature is 1300 ℃
If it is higher, the calcium phosphate compound will be decomposed.

The sintering time (time for maintaining the sintering temperature) is as follows:
In the case of the spark plasma sintering method, the length is short, and generally 5
About 30 minutes is enough. If the sintering time is shorter than 5 minutes, sufficient sintering will not be performed, and if the sintering time is longer than 30 minutes, sintering will not proceed further.

After the completion of sintering, 500
The mixture is allowed to cool to below ℃, the mold is opened, and the composite sintered body is taken out together with the non-sinterable powder. In this way, a composite sintered body 40 of the calcium phosphate compound and the metal having the porous calcium phosphate compound particles 13 ′ protruding on the surface is obtained. The non-sinterable powder attached to the surface of the sintered body can be easily removed with a brush or blast. In addition, if a precalcined powder of a calcium phosphate-based compound such as dense hydroxyapatite is used, there is no problem even if the powder remains partially on the surface.

[2] Composite Sintered Body The composite sintered body 40 of the present invention comprises porous calcium phosphate-based compound particles in a metal matrix 14 ′ comprising a metal powder 14.
13 'is fixed and has a structure in which porous calcium phosphate compound particles 13' protrude from the surface. Therefore, biocompatibility is extremely high, and it can be easily adapted to a living body. In addition, the metal matrix 14 'is transformed into porous calcium phosphate compound particles 13' by pressure sintering.
In the hole. Therefore, high adhesion is obtained, and the calcium phosphate compound particles 13 'do not fall off.

In the present invention, the precalcined porous calcium phosphate compound powder is used, so that the porous calcium phosphate compound particles protruding from the surface of the composite sintered body are formed from the used porous calcium phosphate compound powder. It is substantially unchanged and has about the same average particle size, porosity and pores. That is, the porous calcium phosphate compound particles protruding from the surface of the composite sintered body are 0.5 to 10 mm.
Having an average particle size and a porosity of 20-70%, and the pores are at least partially metal-introduced therein,
Preferably, the size is such that the porous calcium phosphate compound particles are firmly bonded to the metal phase.
It preferably has a diameter of 2000 μm.

Two preferred embodiments of the composite sintered body of the present invention are shown in FIGS. 4 (a) and 4 (b). The composite sintered body 40 of the embodiment shown in FIG. 4 (a) has a surface composed of a mixture of porous calcium phosphate compound particles 13 '+ metal matrix 14' and having porous calcium phosphate compound particles 13 'partially projecting from the surface. It has a sandwich structure consisting of layers 40a, 40a and an inner layer 40b consisting only of a metal matrix 14 'inside them. FIG. 4 (b) shows a composite sintered body entirely composed of a mixture of porous calcium phosphate compound particles 13 'and a metal matrix 14'.

In the embodiment shown in FIG. 4A, the total surface area of the porous calcium phosphate compound particles 13 '/ (the surface area of the surface layer containing the porous calcium phosphate compound particles 13' in the surface layers 40a, 40a). ) Is preferably 5 to 70%. If the area ratio is less than 5%, sufficient biocompatibility cannot be obtained, and if it exceeds 70%, the fixation of the porous calcium phosphate compound particles becomes insufficient. A more preferred area ratio is 20 to 50%.

The area ratio is calculated as follows. That is, the upper and lower surfaces of the sample are copied, and the entire area of the copied copy is the surface area of the surface layer containing the porous calcium phosphate compound particles 13 ′, and this is further divided into white portions (porous calcium phosphate compound particles). And the black portion (metal) are cut out, and the total exposed area of the porous calcium phosphate compound particles 13 'is derived from the total area of the white portions. Then, the area ratio is calculated from the total of the exposed areas and the surface area.

Porous calcium phosphate compound particles 13 '
The average height of the particles protruding from the surface is preferably not more than 1/2 of the average particle size of the particles 13 '. Further, the ratio (projection ratio) of average height / average particle size is preferably 5% or more. If the protrusion ratio is larger than 50%, the porous calcium phosphate compound particles 13 'may fall off. On the other hand, if it is less than 5%, the effect of projecting the porous calcium phosphate compound particles 13 'cannot be sufficiently obtained, and sufficient biocompatibility cannot be obtained.

To obtain such an area ratio and a protrusion ratio, the weight ratio of the porous calcium phosphate compound particles to the metal in the surface layer 40a is preferably 1/20 to 1/4, and 1/10 It is more preferably 〜１ ／. The thickness of the surface layer 40a is not limited as long as the porous calcium phosphate-based compound particles 13 'protrude from the surface, and even if the porous calcium phosphate-based compound particles 13' form a single layer, they form a multiple layer. May be. From a practical viewpoint, the thickness of the surface layer 40a may be about 1 to 5 mm.

The inner layer 40 consisting only of the metal matrix 14 '
The thickness of b is not particularly limited as long as it can obtain sufficient mechanical strength, particularly bending strength, and may be about 1 to 10 mm.

FIG. 5 schematically shows the surface of the composite sintered body 40 in which the porous calcium phosphate compound particles 13 'are exposed.
The porous calcium phosphate compound particles 1 shown in FIG.
The 3 'shape is exaggerated for ease of understanding.
Each porous calcium phosphate-based compound particle 13 'has a large number of fine pores, and a metal matrix 14' enters into relatively large pores. With this structure, the porous calcium phosphate compound particles 13 'are firmly bonded to the metal matrix 14' and do not fall off the surface.

[0062]

The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto.

Example 1 500 g of an aqueous solution containing 1% by weight of methylcellulose
In addition, hydroxyapatite powder 250 with an average particle size of 10 μm
g and kneaded well. The obtained foamed slurry is poured into a mold having a depth of 20 cm, molded, dried, and dried in an air furnace at 1200 m.
Pre-baked at 4 ° C. for 4 hours. By crushing and classifying the obtained pre-fired body, a porous hydroxyapatite powder (granules) having an average particle size of 2.0 to 3.0 mm was obtained.
The porous hydroxyapatite powder had a porosity of 40% and had pores large enough for metal to flow.

A cavity 2a (with an inner surface formed by a carbon mold 2 and a carbon lower punch 4b) of a spark plasma sintering apparatus 1 (SPS-510L manufactured by Sumitomo Coal Mining Co., Ltd.) shown in FIGS. Non-sinterable ceramic powder 12b is covered with carbon paper 11 having a thickness of 200 μm.
1.0 g of a dense hydroxyapatite powder (average particle size: 40 μm) prefired at 1200 ° C. Then, 0.2 g of the above-mentioned porous hydroxyapatite powder, 2.50 g of stainless steel SUS316L powder (average particle size: 25 μm) and 0.20 g of the above-mentioned porous hydroxyapatite powder were sequentially filled, and finally non-sintered. 1.0 g of a dense hydroxyapatite powder preliminarily baked as described above was filled as the conductive ceramic powder 12a.

The pressure inside the vacuum chamber 6 is reduced to a degree of vacuum of 10 ^-2 Torr, and the upper punch 4a made of carbon is lowered to 200 kPa.
Pressurization of gf / cm ² was performed. From power supply 8, both punches 4a, 4b
A pulse voltage was applied in between. The pulse voltage is 4 V and t ₁
/ T ₀ = 12/2 (33.3 msec./5.55 msec., Respectively). Thus, the powder to be sintered 3 was heated to 900 ° C. and held for 10 minutes for sintering. After sintering, keep the pressurized state
It was allowed to cool to 500 ° C. or lower and a sintered body was taken out. The shape of the obtained composite sintered body is oval in cross section, length 2.5 cm, height
The diameter was 0.52 cm, the width was 0.5 cm, and the radius of the arc at both ends was 0.25 cm. The area ratio of the porous hydroxyapatite particles is
At 41%, there was a protrusion of up to 1.1 mm.

The flexural strength of the composite sintered body was measured and found to be 4100 kgf / cm ² . Flexural strength is span
It was calculated from the following equation from a 1.7 cm 3 point bending test (the same applies to Examples 2, 3 and Comparative Examples). Strength (kgf / cm ² ) = (3 × P × L) / (2 × a ×
b ² ) P: Breaking load (kgf) L: Span (cm) a: Height of specimen (sintered body) b: Width of specimen (sintered body) (cm)

Further, in order to measure the peel strength of the porous hydroxyapatite particles in the composite sintered body, an attempt was made to repel and detach the porous hydroxyapatite particles on the surface with a patterned needle. In addition, it was tried to perform a water washing treatment for 30 minutes with an ultrasonic washing machine (270 W) to remove the water. As a result, no peeling or falling off of the porous hydroxyapatite was observed in any case, and it was found that the adhesion of the porous hydroxyapatite particles to the metal phase was very good.

Example 2 A foamed slurry obtained in the same manner as in Example 1 was
Poured into a mold, dried and dried in an air furnace at 1200 ° C.
Pre-baked for hours. By crushing and classifying the prefired body, a porous hydroxyapatite powder (granules) having an average particle size of 2.0 to 3.0 mm was obtained. The porous hydroxyapatite powder had a porosity of 40% and had pores large enough for metal to flow.

As in the first embodiment, the non-sinterable ceramic powder is placed in the cavity 2a formed by the carbon mold 2 and the carbon lower punch 4b of the spark plasma sintering apparatus 1 shown in FIGS. Dense hydroxyapatite powder (average particle size: 40μ)
m) 1.0 g was charged. Then, 0.25 g of the above-mentioned porous hydroxyapatite powder, 2.50 g of stainless steel SUS316L powder (average particle size: 150 μm) and 0.25 g of the above-mentioned porous hydroxyapatite powder were sequentially filled, and finally non-baked. 1.0 g of a dense hydroxyapatite powder preliminarily baked as described above was filled as the binding ceramic powder 12a.

The pressure inside the vacuum chamber 6 is reduced to a degree of vacuum of 10 ^-2 Torr, and the carbon upper punch 4a is lowered to 300 kPa.
Pressurization of gf / cm ² was performed. From power supply 8, both punches 4a, 4b
A pulse voltage was applied in between. The pulse voltage is 4 V and t ₁
/ T ₀ = 12/2 (33.3 msec./5.55 msec., Respectively). Thereby, the powder 3 to be sintered was heated to 1000 ° C. and held for 5 minutes for sintering. After sintering, keep the pressurized state
It was allowed to cool to 500 ° C. or lower and a sintered body was taken out. The shape of the obtained composite sintered body is oval in cross section, length 2.5 cm, height
The diameter was 0.54 cm, the width was 0.5 cm, and the radius of the arc at both ends was 0.25 cm. The area ratio of the porous hydroxyapatite particles is
At 46%, there was a protrusion of up to 1.0mm.

The three-point bending strength of the composite sintered body was 5900 kgf
/ Cm ² . In the same measurement of the peel strength as in Example 1, no peeling or falling off of the porous hydroxyapatite was observed, and it was found that the adhesion of the porous hydroxyapatite particles to the metal phase was very good.

Example 3 A foamed slurry obtained in the same manner as in Example 1 was
Poured into a mold, dried and dried in an air oven at 1000 ° C.
Pre-baked for hours. By crushing and classifying the prefired body, a porous hydroxyapatite powder (granules) having an average particle size of 3.0 to 4.0 mm was obtained. The porous hydroxyapatite powder had a porosity of 30% and had pores large enough for metal to flow.

As in the first embodiment, the non-sinterable ceramic powder is placed in the cavity 2a formed by the carbon mold 2 and the carbon lower punch 4b of the spark plasma sintering apparatus 1 shown in FIGS. Dense hydroxyapatite powder (average particle size: 40μ)
m) 1.0 g was charged. Then, 0.20 g of the above-mentioned porous hydroxyapatite powder, 5.00 g of silver powder (average particle size: 100 μm) and 0.20 g of the above-mentioned porous hydroxyapatite powder were sequentially filled, and finally, As the ceramic powder 12a, 1.0 g of the above-mentioned pre-fired dense hydroxyapatite powder was filled.

The pressure inside the vacuum chamber 6 is reduced to a degree of vacuum of 10 ^-2 Torr, and the carbon upper punch 4a is lowered to
Pressurization of gf / cm ² was performed. From power supply 8, both punches 4a, 4b
A pulse voltage was applied in between. The pulse voltage is 4 V and t ₁
/ T ₀ = 12/2 (33.3 msec./5.55 msec., Respectively). Thus, the sintering powder 3 was heated to 700 ° C. and held for 10 minutes for sintering. After sintering, keep the pressurized state
It was allowed to cool to 500 ° C. or lower and a sintered body was taken out. The shape of the obtained composite sintered body is oval in cross section, length 2.5 cm, height
The diameter was 0.64 cm, the width was 0.5 cm, and the radius of the arc at both ends was 0.25 cm. The area ratio of the porous hydroxyapatite particles is
At 42%, there was a protrusion of up to 1.6mm.

The three-point bending strength of the composite sintered body is 4400 kgf
/ Cm ² . In the same measurement of the peel strength as in Example 1, no peeling or falling off of the porous hydroxyapatite was observed, and it was found that the adhesion of the porous hydroxyapatite particles to the metal phase was very good.

Comparative Example A foamed slurry obtained in the same manner as in Example 1 was
Poured into a mold, dried and dried in an air furnace at 1200 ° C.
Pre-baked for hours. By crushing and classifying the prefired body, a porous hydroxyapatite powder (granules) having an average particle size of 2.0 to 3.0 mm was obtained. The porous hydroxyapatite powder had a porosity of 40% and had pores large enough for metal to flow.

As in the first embodiment, the non-sinterable ceramic powder is placed in the cavity 2a formed by the carbon mold 2 and the carbon lower punch 4b of the spark plasma sintering apparatus 1 shown in FIGS. Dense hydroxyapatite powder (average particle size: 40μ)
m) 1.0 g was charged. On top of that, 0.20 g of the above-mentioned porous hydroxyapatite powder was filled, and 2.50 g of a SUS316L block and 0.20 g of a SUS316L block formed so that the powder did not enter.
g of the above-mentioned porous hydroxyapatite powder, and finally 1.0 g of the pre-fired dense hydroxyapatite powder as a non-sinterable ceramic powder 12a.
Was charged.

The pressure in the vacuum chamber 6 is reduced to a degree of vacuum of 10 ^-2 Torr, and the carbon upper punch 4a is lowered to 200 kPa.
Pressurization of gf / cm ² was performed. From power supply 8, both punches 4a, 4b
A pulse voltage was applied in between. The pulse voltage is 4 V and t ₁
/ T ₀ = 12/2 (33.3 msec./5.55 msec., Respectively). Thus, the powder to be sintered 3 was heated to 900 ° C. and held for 10 minutes for sintering. After sintering, keep the pressurized state
It was allowed to cool to 500 ° C. or lower and a sintered body was taken out. The shape of the obtained composite sintered body is oval in cross section, length 2.5 cm, height
The diameter was 0.28 cm, the width was 0.5 cm, and the radius of the arc at both ends was 0.25 cm. The area ratio of the porous hydroxyapatite particles was 2%, with a maximum protrusion of 0.1 mm. Also, when the molded body was removed from the mold, many porous hydroxyapatite particles dropped off from the SUS316L block.

The three-point bending strength of the composite sintered body is 5900 kgf
/ Cm ² . In the same measurement of the peel strength as in Example 1, the remaining porous hydroxyapatite was observed to fall off.

[0080]

As described above, the composite sintered body of the porous calcium phosphate compound particles and the metal powder of the present invention has extremely high biocompatibility because the porous calcium phosphate compound particles protrude from the surface. It can be easily adapted to living organisms and has high mechanical strength, especially bending strength, because it has a metal phase. Further, since the metal has entered the pores of the porous calcium phosphate compound particles on the surface, there is an advantage that the falling off of the porous calcium phosphate compound particles can be prevented. The composite sintered body of the present invention having such a structure is suitable for applications such as artificial roots and bone reinforcing materials.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of a spark plasma sintering apparatus for carrying out a method of the present invention.

FIG. 2 is a longitudinal sectional view showing a state in which a molding die of the spark plasma sintering apparatus of FIG. 1 is filled with a powder to be sintered.

FIG. 3 is an exploded view showing a forming part of the spark plasma sintering apparatus of FIG.

FIG. 4 is a longitudinal sectional view showing the structure of a composite sintered body 3 of porous calcium phosphate compound particles and metal powder of the present invention, wherein (a) contains porous calcium phosphate compound particles in both surface layers. 1 shows a sandwich structure, and (b) shows a structure entirely containing porous calcium phosphate compound particles.

FIG. 5 is a partially enlarged view showing porous calcium phosphate compound particles protruding from the surface of the composite sintered body of the present invention.

[Explanation of symbols]

 1. Spark sintering apparatus 2. Mold 3. Mold powder 4a, 4b Punch 5a, 5b Ram 6. Vacuum chamber 7. ... Vacuum pump 8 ... Power supply 9 ... Pressure drive mechanism 10 ... Control unit 11 ... Carbon paper 12a, 12b ... Flexible made of non-sinterable powder Layer 13: porous calcium phosphate compound powder 13 ': porous calcium phosphate compound particles 14: metal powder 14': metal matrix 40: composite sintered body 40a ... Surface layer 40b ... Inner layer (metal layer)

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 4C081 AB04 AB06 BA13 BB08 CF012 CF032 CF122 CF132 CF142 CF152 CF162 CG01 CG02 CG03 CG04 CG05 CG07 DA01 DA11 DB03 DB06 DB07 DC03 EA02 EA04 EA15 4G019 FA11 4K018 AA02 BA03A33 EA22 JA07 JA16 KA22

Claims (15)

[Claims] 1. A composite sintered body of porous calcium phosphate compound particles and a metal, wherein at least a part of the surface has a surface layer containing the porous calcium phosphate compound particles, and A composite sintered body characterized in that a part thereof protrudes from the surface. 2. The composite sintered body according to claim 1, wherein
A composite sintered body comprising a surface layer made of porous calcium phosphate compound particles and a metal, and an inner layer whose inside substantially consists only of a metal. 3. The composite sintered body according to claim 1, wherein a ratio of (total exposed area of porous calcium phosphate compound particles) / (surface area of surface layer containing porous calcium phosphate compound particles). (Area ratio) is 5 to 70%
A composite sintered body, characterized in that: 4. The composite sintered body according to claim 1, wherein, among the porous calcium phosphate compound particles protruding from the surface of the composite sintered body, the average height of the protruding portion is average. A composite sintered body having a particle size of not more than half the particle size. 5. The composite sintered body according to claim 1, wherein the porous calcium phosphate compound particles have an average particle size of 0.5 to 10 mm and a porosity of 20 to 70%. A composite sintered body characterized in that a metal at least partially enters pores of porous calcium phosphate compound particles, and that the porous calcium phosphate compound particles are firmly bonded to a metal phase. 6. The composite sintered body according to claim 1, wherein the metal is Ti, Cr, Fe, Co, Cu, Mo,
A composite sintered body characterized by being a metal selected from the group consisting of Ag, Au, Pd, Pt, Al and Ni or an alloy thereof. 7. The composite sintered body according to claim 1, wherein the weight ratio of the porous calcium phosphate-based compound particles to the metal in the surface layer is 1/20 to 20.
A composite sintered body characterized in that it is 1/4. 8. The method for producing a composite sintered body of porous calcium phosphate compound particles and a metal according to claim 1, wherein the calcium phosphate compound powder is heated at a temperature not lower than the sintering start temperature. A porous calcium phosphate compound powder is prepared by pre-baking, and the porous calcium phosphate compound powder and the metal powder are combined such that the porous calcium phosphate compound powder is present on at least a part of the surface. And a step of covering the outside of the porous calcium phosphate compound powder with a flexible layer made of a powder that does not sinter at the sintering temperature of the composite sintered body and performing pressure sintering. 9. The method for producing a composite sintered body according to claim 8, wherein the precalcination temperature of the porous calcium phosphate compound particles is 700 to 1300 ° C. 10. The method for producing a composite sintered body according to claim 8, wherein a spark plasma sintering method is performed as the pressure sintering method. 11. The method for producing a composite sintered body according to claim 8, wherein the porous calcium phosphate compound powder has an average particle size of 0.5 to 10 mm and a porosity of 20 to 70%. The method according to claim 1, wherein at least a part of the pores of the porous calcium phosphate compound powder has a size that metal can enter. 12. The method for producing a composite sintered body according to claim 8, wherein the powder not sintered at the sintering temperature is a ceramic powder having a higher melting point than the metal powder. A method characterized by: 13. The method for producing a composite sintered body according to claim 12, wherein the ceramic powder is a pre-fired powder of a calcium phosphate compound, a carbon powder, an alumina powder,
A method characterized by being at least one selected from the group consisting of zirconia powder, boron nitride powder and silicon nitride powder. 14. The method for producing a composite sintered body according to claim 8, wherein the metal powder has a particle size of 1 to 500 μm.
m. having a mean particle size of m. 15. The method for producing a composite sintered body according to claim 8, wherein the sintering temperature is 500 to 1300 ° C., and the time for maintaining the sintering temperature is 5 to 30 minutes. A method comprising: