JPS6025383B2 - Method for producing calcium phosphate sintered body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Calcium phosphate powder usually exists as a very fine powder, and it has been difficult to obtain a strong and dense compact.

Recently, bioceramics as biomaterials for teeth, bones, etc., high-grade secret ceramic substrates, heat-resistant materials in combination with metals,
In order to use it for other applications such as ferrite magnetic head fixing bases for VTRs and tape recorders, it is necessary to mold calcium phosphate powder to obtain a product with high physical strength. As a method for this, there is currently a well-known hot press method, which can obtain products with good physical properties such as a compressive strength of 1000 to 2000 k9/h, but the drawbacks of this method are that the manufacturing method is complicated and the manufacturing cost is high. has been done. On the other hand, conventional pressureless firing has a simple manufacturing method and low manufacturing cost, but has the drawback of low fiber density, compressive strength of about 900k9/average, and especially low bending strength. As a hot press method, for example, there is a method in which the product is molded under high pressure at room temperature of 500 k9 or more and then fired under a hot press of 110,000 or 130 k9 for 1 hour. The object of the present invention is to eliminate the above-mentioned drawbacks of the conventional method and to obtain a strong fibrous calcium phosphate mirror body by an atmospheric pressure firing method.

That is, in the present invention, the atomic ratio of calcium/phosphorus is from 1.40 to
It is characterized by adding and mixing 0.1 to 15% by weight of phosphoric acid based on the calcium phosphate component after firing to a powder mainly composed of 1.75% calcium phosphate, and then solidifying the mixture. The present invention will be explained in detail below. The powder mainly composed of calcium phosphate used in the present invention belongs to calcium compounds that can be calcined at high temperature in the presence of phosphoric acid to form calcium phosphate, and the starting material powder includes:
Preferably hydroxyapatite 1'2 (Ca(OH)2 father a
3(P04)2) or tricalcium phosphate can be used.

Such starting material powder can also be prepared by adding a calcium salt such as calcium carbonate to a calcium phosphate raw material such as calcium pyrophosphate or monobasic calcium phosphate as a main component to obtain a composition similar to hydroxyapatite or tribasic calcium phosphate. However, it can be obtained by heat treatment (fake light) at 700 to 1400 oO. Regarding this,
Monma, Kanazawa, Ishisuga Lime Society 54th Academic Lecture Summary 10
(1977) and Monma, Kanazawa, 16th Ceramics Basic Discussion Group, 7th Page (197 Gunou), and Kanazawa, Umegaki, Ceramics 10 [7] P463 (1975).
The calcium/phosphorus atomic ratio of tricalcium phosphate is 3/
2. The atomic ratio of hydroxyapatite is 5/3, but in the present invention, the composition of the starting raw material powder is such that the atomic ratio of calcium/phosphorus (Ca/P) is in the range of 1.40 to 1.75. shall be. Phosphoric acid is added and mixed to this starting raw material powder in an amount of 0.1 to 15% by weight, preferably 1 to 1% by weight, based on the calcium phosphate component in the sintered body after firing. Phosphoric acid 0
．． If it is less than 1, the addition effect will not be obtained and the strength will not improve. On the other hand, if phosphoric acid exceeds 15%, a compound with a low melting point will be produced, and the strength will not improve. When this phosphoric acid is added and mixed, an organic binder such as gum arabic or camphor dissolved in an ether solvent is simultaneously added and mixed, and press molding is performed. Thereafter, firing is performed at about 1,000 to 150,000C, preferably about 1,150 to 14,000C, but normal pressure firing is sufficient in the present invention. Since the firing conditions for this firing are wide as described above, the firing can be easily performed. The differences in effects between the firing method according to the present invention and the conventional method (normal pressure method) are as shown in the drawings.

That is, in the case of hydroxyapatite alone (sample 1) and in the case of adding 5% phosphoric acid to hydroxyapatite powder (sample 3).
) The effect of the method of the present invention becomes clear by comparing the strength at each firing temperature. In addition, the crystal grain size of the sintered body obtained by sintering with the addition of phosphoric acid is 21 to 20.
It was found that grain growth was suppressed compared to products containing hydroxyapatite alone and other additives.

Examples of the present invention will be illustratively described below, including those based on the follow-up method. Example
．． Add and mix prescribed amounts of phosphoric acid to calcium phosphate powder, add and mix 3% by weight of camphor as a binder dissolved in ether, mold at a press pressure of 800 k9/base, and heat the molded product at 30,000/HR. 1
The firing temperature was kept within the range of 000 to 15,000 C for 1 hour each to obtain Akatsuki compacts.

Among the sintered bodies at each of these temperatures, the one having the maximum strength was taken as the value of the bending strength of each sample. The results are shown in Table 1. As described in detail above, the present invention provides a method for producing a high-quality dense calcium phosphate composite with excellent strength through atmospheric pressure firing, and the composite is suitable for use as biomaterials such as bones and teeth. Furthermore, it can be used as a high-grade dense ceramic substrate for industrial use, especially as a material for the electronic industry, and other base materials.

Also, its thermal expansion coefficient is Q=90~130~10-7℃
-1, which is close to that of metal, making it extremely useful as a material for heat-resistant composites used in conjunction with metal and silk. Further, since the expansion coefficient is close to that of ferrite (Q2100×10-700-1), it is extremely useful as a ceramic composition for magnetic head fasteners for VTRs, tape decks, etc. That is, it is rare to find a material that has a high melting point and a thermal expansion coefficient similar to that of ferrite. Table I *Temporary 1000℃

[Brief explanation of the drawing]

The drawings show the relationship between the firing temperature and bending strength of bran compacts according to an embodiment of the present invention and a conventional method.

Claims (1)

[Scope of Claims] 1. Powder mainly composed of calcium phosphate with a calcium/phosphorus atomic ratio of 1.40 to 1.75, and 0.1 to 15% by weight of phosphorus based on the calcium phosphate component after firing. A method for producing a calcium phosphate sintered body, which comprises adding and mixing an acid and sintering the mixture. 2 In claim 1, phosphoric acid is 1 to 10
A method for producing a sintered body of calcium phosphate, the method comprising adding % by weight of calcium phosphate. 3. The method for producing a calcium phosphate sintered body according to claim 1, characterized in that the powder mainly composed of calcium phosphate is hydroxyapatite and/or tricalcium phosphate.