Ceramic biomaterials, biocomponents, and manufacturing method for biocomponents

Abstract

To provide a novel ceramic biomaterial suitable for a biological part.SOLUTION: A ceramic biomaterial of a certain embodiment is constituted of a sintered body including silicon nitride and a sintering additive and having a bending strength of 1196 MPa or more. The ceramic biomaterial may include 88.0-98.0 mass% of the silicon nitride, and may include 2.0-12.0 mass% of the sintering additive.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to ceramic biomaterials. [Background technology]

[0002] A variety of biomaterials have been devised for implantation in living bodies such as humans and animals. Examples of biomaterials include artificial bones that are prone to wear due to sliding, such as artificial hip joint heads and artificial acetabular cups, and artificial tooth roots that require chemical stability. For example, Patent Document 1 discloses an alumina-zirconia composite ceramic material as a biomaterial. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Patent No. 9,353,010 Summary of the Invention [Problem to be solved by the invention]

[0004] However, alumina-zirconia composite ceramic materials have problems common to ceramic materials, such as sudden chipping and squeaking noise due to brittleness. Furthermore, when these ceramic materials are used in artificial bones, which are prone to wear due to sliding, there is room for further improvement in their wear resistance.

[0005] The present invention has been made in view of the above circumstances, and one of its objects is to provide a new ceramic biomaterial suitable for biocomponents. [Means for solving the problem]

[0006] In order to solve the above problems, a ceramic biomaterial according to one embodiment of the present invention comprises silicon nitride and a sintering aid, and is composed of a sintered body having a bending strength of 1196 MPa or more.

[0007] According to this embodiment, strength and abrasion resistance suitable for biological parts can be achieved.

[0008] The composition may contain 88.0 to 98.0 mass % of silicon nitride and 2.0 to 12.0 mass % of a sintering aid.

[0009] The silicon nitride may contain β-type columnar crystals, which suppresses microscopic chipping and breakage such as cracks.

[0010] The sintering aid may contain at least one oxide selected from the group consisting of rare earth oxides and aluminum oxide, thereby realizing a biomaterial whose main component is silicon nitride, which is difficult to sinter by itself.

[0011] The sintered body may have a fracture toughness of 7.0 or more, which allows it to be used for biocomponents with high hardness and excellent wear resistance.

[0012] The total content of iron and calcium, which are unavoidable impurities, may be 500 ppm or less, thereby realizing a ceramic biomaterial with high strength and excellent wear resistance.

[0013] The material may be processed into a shape suitable for a joint, thereby enabling it to be used in a joint that requires high strength and wear resistance.

[0014] In the observation field of the SEM image of the sintered body observed with a scanning electron microscope (SEM), the number of particles with a longitudinal diameter of 1 μm or less was 4.5 [particles / μm 2

[0033] or more. This improves the wear resistance due to the structure of the fine particles.

[0015] Peak intensity of the (101) plane of silicon nitride by X-ray diffraction analysis of sintered bodies I (101) and (210) plane peak intensity I (210) Relative to I (101) / I (210)The (101) plane of the hexagonal crystal system is a plane tilted at about 20 degrees with respect to the base of the hexagonal prism, and the (210) plane is a plane parallel to the side of the hexagonal prism. Therefore, the ratio of the peak intensities I (101) / I (210) If I is large, it suggests that there are many spherical particles with (101) faces, and if it is small, there are many columnar particles with (210) faces. (101) / I (210) When is larger than 1.0, preferably 1.3 or more, and more preferably 1.5 or more, the proportion of spherical particles smaller than the columnar particles increases, improving the abrasion resistance.

[0016] Another aspect of the present invention is a biocomponent. This biocomponent is made of the aforementioned ceramic biomaterial and is to be embedded in a living body. The surface roughness (arithmetic mean roughness Sa) of the sliding portion between the biocomponent and other components is 0.025 μm or less. This allows for the realization of a biocomponent with excellent wear resistance.

[0017] Yet another aspect of the present invention is a method for producing a biocomponent, which comprises mixing silicon nitride powder containing unavoidable impurities, iron and calcium, at a total content of 300 ppm or less, with a sintering aid powder, and sintering the mixture at a temperature of 1600 to 1900°C and a pressure of 20 to 35 MPa.

[0018] According to this embodiment, it is possible to manufacture a biocomponent that can reduce microscopic chipping and breakage such as cracks.

[0019] Any combination of the above components and any transformation of the present invention into a method, device, system, etc. are also valid aspects of the present invention. Appropriate combinations of the above elements may also be included in the scope of the invention for which patent protection is sought by this patent application. [Effects of the Invention]

[0020] According to the present invention, a new ceramic biomaterial suitable for biocomponents can be realized. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a schematic diagram of an artificial hip joint, which is an example of a biological component according to the present embodiment. [Figure 2] FIG. 10 is a diagram showing the variation of dynamic load during testing. [Figure 3] FIG. 2 is an exploded perspective view of a jig for fixing a disk. [Figure 4] FIG. 10 is an exploded perspective view of a jig for fixing a pin. [Figure 5] FIG. 1 is a conceptual diagram of a sliding test performed while pressing a pin against a disk. [Figure 6] FIG. 10 is a diagram showing the relationship between the wear amount and sliding distance of the disks according to Comparative Example 1 and Reference Example 1. [Figure 7] FIG. 10 is a diagram showing the relationship between the amount of wear and the sliding distance of the pins according to Reference Example 1 and Example 1. [Figure 8] FIG. 8(a) is a scanning electron microscope (SEM) image of the ceramic biomaterial according to Reference Example 1, and FIG. 8(b) is a SEM image of the ceramic biomaterial according to Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0022] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are designated by the same reference numerals, and redundant description will be omitted where appropriate.

[0023] The ceramic biomaterial according to this embodiment can be used for various biological components implanted in the body to support or replace bones. In particular, when a biological component is used as a replacement for a joint where bones slide against each other, such as a hip joint or a knee joint, wear resistance is required in addition to the strength of the biological component itself, making the ceramic biomaterial according to this embodiment suitable for such joints. Below, an example in which the biological component according to this embodiment is applied to a hip joint will be described.

[0024] (artificial hip joint) Figure 1 is a schematic diagram of an artificial hip joint, which is an example of a biocomponent according to this embodiment. The artificial hip joint 10 shown in Figure 1 has a femoral head 16 fixed to one end of a stem 14 inserted into a femur 12, and a cup 24 and cup insert 26 fixed to an acetabulum 22 of a pelvis 18. The cup 24 is sometimes called a socket, and the cup insert 26 is sometimes called a liner. The artificial hip joint 10 according to this embodiment is assumed to have a spherical femoral head 16 and a hemispherical, bowl-shaped cup insert 26 made of a ceramic biomaterial.

[0025] If the material strength of the cup insert 26 is low, the cup insert 26 itself must be thickened. As a result, the inner diameter of the cup insert 26 becomes smaller, and the outer diameter of the femoral head 16 attached to the cup insert 26 also becomes smaller. As a result, the femoral head 16 becomes more likely to come off the cup insert 26, i.e., to dislocate. Therefore, by manufacturing a biocomponent using a relatively high-strength material such as the ceramic biomaterial of the present embodiment, it is possible to thin the cup insert 26 and thereby increase the diameter of the femoral head 16, thereby achieving an artificial hip joint 10 that is less susceptible to dislocation.

[0026] (Method of manufacturing sintered body) As a result of extensive research into ceramics suitable for biomaterials such as artificial joints, the inventors discovered that a sintered body made by adding a sintering aid to silicon nitride (Si3N4), the main component, is suitable for biomaterials. First, a method for manufacturing a sintered body suitable for ceramic biomaterials will be described.

[0027] First, a main raw material powder containing 88.0 to 98.0 mass % of silicon nitride is mixed with 2.0 to 12.0 mass % of a sintering aid component to prepare a raw material powder. This mixing can be carried out, for example, by a wet ball mill or the like.

[0028] In addition to the main components, silicon nitride raw materials contain inevitable impurities such as metals, oxygen, and carbon (Fe, Al, Ca, Cl, O, C, Si, Na, Mg, etc.), and the present inventors have conceived the possibility of realizing a ceramic biomaterial with high strength and excellent wear resistance by reducing the amount of these impurities. For example, it is recommended to use raw material powder with a silicon nitride purity of 95.0% or more, preferably 99.0% or more, and more preferably 99.5% or more. Furthermore, it is recommended that the amount of inevitable impurities contained in the silicon nitride raw material powder be 5000 ppm or less, preferably 500 ppm or less, and more preferably 50 ppm or less. The specific surface area of ​​the silicon nitride raw material powder is 6 [m 2 / g] or more, preferably 9 to 13 [m 2 / g]. The α fraction of silicon nitride (the proportion of α phase in the whole) is preferably 90% or more, and more preferably 94% or more.

[0029] The sintering aid can be selected from those used in sintering silicon nitride. The sintering aid is one or more of aluminum oxide (alumina), magnesium oxide (magnesia), yttrium oxide (yttria), or other lanthanoid metal oxides (rare earth oxides). For example, it can be a mixture of alumina and yttria, a mixture to which magnesia is further added, or a mixture of yttria and magnesia. The amount of the sintering aid component is preferably 2.0 to 12.0 mass% of the total raw material powder, preferably 4.0 to 10.0 mass%, and more preferably 4.0 to 8.0 mass%. Furthermore, the amount of unavoidable impurities contained in the raw material powder of the sintering aid should be 100 ppm or less, preferably 50 ppm or less.

[0030] Next, the raw material powder is sintered under high temperature and pressure to form a sintered body. This sintering can be performed, for example, by hot pressing. Hot pressing is performed in a non-oxidizing atmosphere, such as an argon or nitrogen atmosphere, but it can also be performed in pressurized nitrogen. The hot pressing temperature should be in the range of 1600 to 1900°C. If the temperature is too low, sintering will be insufficient, and if it is too high, thermal decomposition of the main raw materials will occur. A pressure of 20 to 35 MPa is appropriate. The duration of hot pressing will depend on the temperature and dimensions, but is usually about 1 to 4 hours. High-temperature pressure sintering can also be performed by HIP (hot isostatic pressing). In this case, the sintering conditions can also be appropriately determined by those skilled in the art.

[0031] The ceramic biomaterials composed of sintered bodies manufactured by the above-mentioned method were measured for bending strength [MPa] based on JIS R1601 and fracture toughness K based on JIS R1607. IC [MPa m 1 / 2 In addition, to compare the abrasion resistance, the amount of abrasion was measured in the following abrasion test.

[0032] (wear test) A wear test was conducted with reference to ISO 14242, "Implants for surgical wear of total hip joint prostheses." The test was conducted under variable load conditions simulating the walking environment, assuming the use of artificial joint components. Figure 2 shows the dynamic load fluctuations during the test. The stress fluctuation range was 0.27 to 2.73 MPa. For the wear test, a pin and a disk of a predetermined shape that come into contact and slide against each other are prepared. The disk, made of the ceramic biomaterial according to this embodiment, is a circular part with a diameter of 40 mm and a thickness of 3 mm. The pin, also made of the ceramic biomaterial according to this embodiment, is a cylindrical part with a length of 15 mm, the tip surface that comes into contact with the disk being a circle with a diameter of 4 mm.

[0033] Fig. 3 is an exploded perspective view of a jig for fixing a disk. Fig. 4 is an exploded perspective view of a jig for fixing a pin. Fig. 5 is a conceptual diagram of a sliding test conducted while pressing a pin against a disk. As shown in Fig. 3, disk 30 is placed in a circular recess 32a of disk receiving jig 32 with buffer material 34 interposed therebetween, and a ring-shaped disk holding jig 36 is fixed to disk receiving jig 32 using bolts 38, whereby disk 30 is sandwiched and fixed between disk receiving jig 32 and disk holding jig 36.

[0034] 4, after the pin 40 is inserted into the collet 42, the collet 42 is inserted into a tapered hole in a collet receiving jig 44, and a threaded collet holding jig 46 is attached and fixed to the collet receiving jig 44. The collet receiving jig 44 is fixed to a strain gauge plate 48. The strain gauge plate 48 is fastened to an L-shaped block 52 with bolts 54 via spacers 50.

[0035] 5, pin 40 protruding from collet holding jig 46 is pressed against disk 30 fixed to disk receiving jig 32, disk receiving jig 32 is rotated, and L-shaped block 52 is moved by an external drive device in a direction parallel to the rotation axis of disk 30 (direction along the rotation axis). Then, the movement of L-shaped block 52 is controlled so that pin 40 is pressed against disk 30 while sliding with a predetermined load fluctuation.

[0036] The sliding environment was a wet wear test using purified simulated synovial fluid prepared by adding 0.08 g of sodium hyaluronate (derived from cockscomb) to 200 mL of physiological saline. The test conditions were a sliding speed of 20 mm / s, one load cycle of 40 s, and a simulated synovial fluid temperature of 37.0 ± 2.0°C.

[0037] (Comparative Example 1) Using commercially available biomaterials, the pin was made of zirconia material and the disk was made of alumina-zirconia composite ceramics, and the above-mentioned wear test was carried out.

[0038] (Reference example 1) The pin and disk were made of silicon nitride ceramics. 90 mass% of the silicon nitride raw material (Sample 1) manufactured by a commercially available direct nitriding method, 6 mass% of the raw material for yttria, a sintering aid, and 4 mass% of the raw material for alumina, also a sintering aid, were weighed out, and a sintered body was produced at a firing temperature of 1700°C based on the manufacturing method described above. The silicon nitride manufactured by the commercially available direct nitriding method had an alpha phase rate (the proportion of alpha phase in the total) of 91%, an average particle size (measured by laser diffraction and scattering method (Microtrac)) of 1.1 μm, and a specific surface area (measured by BET method) of 6 m 2 / g, and contains the following impurities: iron (Fe) 2000 ppm, aluminum (Al) 1000 ppm, calcium (Ca) 2000 ppm, carbon (C) 0.1%, and oxygen (O) 1.5%.

[0039] Fig. 6 is a diagram showing the relationship between the amount of wear and the sliding distance of the disks according to Comparative Example 1 and Reference Example 1. In the wear test, the masses of the disks and pins were measured at predetermined sliding distances, and the amount of wear per unit area was calculated and graphed. As shown in Fig. 6, it can be seen that the amount of wear of the silicon nitride-based sintered body of Reference Example 1 was reduced to about half that of the zirconia-based sintered body of Comparative Example 1.

[0040] Tables 1 and 2 show the firing temperatures, raw material compositions, bending strengths, and fracture toughnesses of the ceramic biomaterials according to Reference Example 1 and Examples 1 to 11.

[0041] [Table 1]

[0042] [Table 2]

[0043] The ceramic biomaterial according to Reference Example 1 has improved wear resistance, but there is room for improvement in bending strength and fracture toughness.

[0044] Example 1 As the raw material for silicon nitride, 94 mass% of a raw material (sample 2) produced by a commercially available imide pyrolysis method, 4 mass% of a raw material for yttria as a sintering aid, and 2 mass% of a raw material for alumina as a sintering aid were weighed out, and a sintered body was produced at a firing temperature of 1750°C based on the aforementioned manufacturing method. The commercially available silicon nitride produced by the imide pyrolysis method has an alpha conversion rate of 95% or more and a specific surface area of ​​9 to 13 m 2 / g, and contains the following impurities: iron 10 ppm, aluminum 1 ppm, calcium 1 ppm or less, carbon (C) 0.1%, and oxygen (O) 2.0% or less.

[0045] 7 is a diagram showing the relationship between the amount of wear and the sliding distance of the pin according to Reference Example 1 and Example 1. As shown in FIG. 7, it can be seen that the amount of wear of the silicon nitride-based sintered body of Example 1 is reduced to about half that of the silicon nitride-based sintered body of Reference Example 1. There are various possible reasons for this, including the fact that the amount of sintering aid in the sintered body according to Example 1 is reduced compared to the sintered body according to Reference Example 1, and that Sample 2, the raw material for the silicon nitride of Example 1, has a much lower amount of unavoidable impurities and is a finer raw material powder than Sample 1, the raw material for the silicon nitride of Reference Example 1, resulting in a finer structure for the sintered body.

[0046] Moreover, the ceramic biomaterial according to Example 1 has significantly improved bending strength and fracture toughness compared to Reference Example 1, which contributes to the miniaturization and thinning of biocomponents.

[0047] Example 2 The ceramic biomaterial of Example 2 differs from Example 1 mainly in that the amount of sintering aid is 10 mass % and the firing temperature is 1700°C. The ceramic biomaterial of Example 2 has lower bending strength and fracture toughness than Example 1, but the values ​​are higher than those of the ceramic biomaterial of Reference Example 1. In other words, it is clear that it is preferable to use Sample 2 as a raw material for silicon nitride.

[0048] (Examples 3 to 6) The ceramic biomaterials of Examples 3 to 6 differ mainly from Example 1 in that the amount of sintering aid is 2 to 4 and 8 to 12 mass%. The ceramic biomaterials of Examples 3 to 6 have high bending strength and fracture toughness, similar to Example 1. Furthermore, it was found that the most preferable amount of sintering aid is 6%, as shown in Example 1. It was also revealed that the thickness of the grain boundary layer changes depending on the amount of sintering aid added. Considering the physical properties and smooth structure, it was found that the amount of sintering aid used in Example 1 is 6%.

[0049] Examples 7 to 10 The ceramic biomaterials of Examples 7 to 10 differ from Example 1 mainly in that the amount of sintering aid is 4 to 8, 12 mass % and the firing temperature is 1700° C. The ceramic biomaterials of Examples 7 to 10 have high bending strength and fracture toughness, similar to Example 1.

[0050] Example 11 The ceramic biomaterial of Example 11 differs from Example 1 mainly in that the firing temperature is 1800°C. The ceramic biomaterial of Example 11 has slightly lower bending strength and fracture toughness than Example 1, but the values ​​are higher than those of the ceramic biomaterial of Reference Example 1.

[0051] As described above, the ceramic biomaterial according to this embodiment contains silicon nitride and a sintering aid, and is composed of a sintered body having a bending strength of 1196 MPa or more and a fracture toughness of 7.0 or more. This allows for the realization of strength, high hardness, and wear resistance suitable for biological components. Furthermore, the improved fracture toughness reduces the occurrence of sudden chipping in vivo. In particular, as shown in Examples 1 to 11, ceramic biomaterials containing 88.0 to 98.0 mass% silicon nitride and 2.0 to 12.0 mass% sintering aid are preferred.

[0052] The ceramic biomaterial according to this embodiment contains columnar crystals of β-type silicon nitride after firing, which prevents microscopic chipping and breakage such as cracks.

[0053] (Structure of sintered body) Next, the structure of the sintered body constituting the ceramic biomaterial will be described. Fig. 8(a) shows a scanning electron microscope (SEM) image of the ceramic biomaterial of Reference Example 1, and Fig. 8(b) shows an SEM image of the ceramic biomaterial of Example 1.

[0054] The microstructures shown in Figures 8(a) and 8(b) are SEM images obtained by observing the surface of a ceramic biomaterial after mirror polishing with diamond slurry and plasma etching (RF power: 40 W, etching gas: CF4 + O2) for 10 minutes using a scanning electron microscope (SEM) at an accelerating voltage of 20 kV. The SEM images shown in Figures 8(a) and 8(b) were taken at a magnification of 15,000x with a field of view of 8.5 μm wide x 6.5 μm long (area 55.25 μm). 2 )

[0055] Comparing the SEM image of the material according to Reference Example 1 shown in FIG. 8(a) with the SEM image of the material according to Example 1 shown in FIG. 8(b), it can be seen that there is a difference in the particle size of the spherical particles other than the columnar particles. The inventors have come to the conclusion that the number of small spherical particles may affect the difference in wear resistance. Specifically, they focused on the number of particles with a longitudinal major axis of 1 μm or less in the observation field of SEM images obtained by observing the sintered bodies constituting the ceramic biomaterials of Reference Example 1 and Example 1 using a scanning electron microscope (SEM).

[0056] In the SEM image of Reference Example 1 shown in FIG. 8(a), the number of particles with a major axis of 1 μm or less in the longitudinal direction is 135, and the number per unit area is 2.4 [particles / μm 2 On the other hand, in the SEM image of Example 1 shown in FIG. 8(b), the number of particles with a major axis of 1 μm or less in the longitudinal direction is 350, and the number per unit area is 6.3 [particles / μm 2]. Therefore, it is thought that if this number is large, the structure becomes finer and wear resistance improves. In addition, squeaking noise is suppressed and phase transition is less likely to occur. Specifically, when the number of particles with a longitudinal diameter of 1 μm or less is 2.5 [particles / μm 2 ] or more, and preferably 4.5 [pieces / μm 2 ] or more. This improves the wear resistance due to the structure of the fine particles.

[0057] (orientation) Next, the preferred crystal orientation will be explained. Silicon nitride (β-Si3N4) has a hexagonal crystal structure, with the (101) plane tilted at approximately 20 degrees with respect to the base of the hexagonal prism, and the (210) plane parallel to the side of the hexagonal prism. Therefore, the intensities of diffraction peaks of specific plane orientations were measured by X-ray diffraction for each of the polycrystalline sintered bodies according to Reference Example 1 and Example 1. More specifically, the peak intensities I of the (101) plane of each of the sintered bodies according to Reference Example 1 and Example 1 were measured. (101) and (210) plane peak intensity I (210) and were measured.

[0058] As a result, the peak intensity (relative intensity) I at 33.7° corresponding to the (101) plane of the sintered body of Reference Example 1 (101) is 30081, the peak intensity (relative intensity) at 36.1° corresponding to the (210) plane is I (210) is 29300, and the ratio I (101) / I (210) On the other hand, the peak intensity (relative intensity) I corresponding to the (101) plane of the sintered body of Example 1 was 1.0. (101) is 50387, the peak intensity (relative intensity) corresponding to the (210) plane is I (210) is 28797, and the ratio I (101) / I (210) was 1.7.

[0059] Ratio of peak intensities I (101) / I (210)If I is large, it suggests that there are many spherical particles with (101) faces, and if it is small, there are many columnar particles with (210) faces. (101) / I (210) When is larger than 1.0, preferably 1.3 or more, and more preferably 1.5 or more, the proportion of spherical particles smaller than the columnar particles increases, improving the abrasion resistance.

[0060] Furthermore, when using the ceramic biomaterial according to this embodiment to fabricate a biocomponent to be implanted in a living body, it is recommended to polish the surface that will be in contact with other components with diamond slurry. Furthermore, it is recommended to perform a process such as a wear test in which ceramics are rubbed against each other. Specifically, it is recommended that the surface roughness (arithmetic mean roughness Sa) of the sliding portion be 0.025 μm or less. Furthermore, the root-mean-square height Sq of the sliding portion may be 0.030 μm or less. Furthermore, the maximum height Sz may be 0.300 μm or less. This allows for the realization of a biocomponent with excellent wear resistance and antibacterial properties.

[0061] In terms of the manufacturing method for biocomponents, it is advisable to mix silicon nitride powder containing unavoidable impurities such as iron and calcium at a total content of 300 ppm or less with a sintering aid powder, and sinter the mixture at a temperature of 1600 to 1900°C and a pressure of 20 to 35 MPa. This makes it possible to manufacture biocomponents in which microscopic chipping and breakage such as cracks are suppressed.

[0062] (Stability in the body) Alumina-zirconia composite ceramics sold as biomaterials are composed of approximately 80% alumina and 20% zirconia. Zirconia is said to be a ceramic that reacts with water (body fluids) and is prone to phase transformations, raising concerns about its long-term stability when implanted in the body. Furthermore, the alumina and zirconia within the composite ceramic structure have different physical properties (hardness, strength, etc.), and minute irregularities that occur during processing make it easy for bacteria to adhere.

[0063] On the other hand, the ceramic biomaterial according to this embodiment is primarily composed of silicon nitride and contains substantially no zirconia, making it less susceptible to phase transformations due to reactions with water (body fluids). Furthermore, because it is a single material, it is less likely to develop minute irregularities during processing, making it less susceptible to bacterial adhesion. Additionally, the thickness of the grain boundary layer changes depending on the amount of sintering aid added. Therefore, considering the physical properties and smooth structure, it became clear that the amount of sintering aid, 6% as in Example 1, was optimal.

[0064] Although the present invention has been described above with reference to the above-mentioned embodiments and examples, the present invention is not limited to the above-mentioned embodiments, and suitable combinations or substitutions of the configurations of the respective embodiments are also included in the present invention. Furthermore, it is possible to suitably rearrange the combinations and order of steps in the embodiments based on the knowledge of a person skilled in the art, and to make modifications to the embodiments such as various design changes, and such modified embodiments are also included in the scope of the present invention. [Explanation of symbols]

[0065] 10 hip prostheses, 12 femoral prostheses, 14 stems, 16 femoral heads, 18 pelvises, 22 acetabular prostheses, 24 cups, 26 cup inserts, 30 discs, 40 pins.

Claims

1. A ceramic biomaterial containing silicon nitride and a sintering aid, and consisting of a sintered body with a bending strength of 1231 MPa or more, and containing unavoidable impurities (Fe, Ca, Cl, C, Na, Mg) in a total amount of 500 ppm or less.

2. The silicon nitride is contained in an amount of 88.0 to 98.0 mass %, 2. The ceramic biomaterial according to claim 1, wherein the sintering aid is contained in an amount of 2.0 to 12.0 mass %.

3. 3. The ceramic biomaterial according to claim 1, wherein the silicon nitride contains β-type columnar crystals.

4. 4. The ceramic biomaterial according to claim 1, wherein the sintering aid contains at least one oxide selected from the group consisting of rare earth oxides and aluminum oxide.

5. 5. The ceramic biomaterial according to claim 1, which is made of a sintered body having a fracture toughness of 7.0 or more.

6. 6. The ceramic biomaterial according to claim 1, wherein the total content of iron and calcium as inevitable impurities is 50 ppm or less.

7. 7. The ceramic biomaterial according to claim 1, which is processed into a shape suitable for a joint.

8. A sintered body containing silicon nitride and a sintering aid and having a bending strength of 1231 MPa or more, In the observation field of the SEM image of the sintered body observed with a scanning electron microscope (SEM), the number of particles having a major axis of 1 μm or less in the longitudinal direction was 4.5 [particles / μm ２ ] or more.

9. A sintered body containing silicon nitride and a sintering aid and having a bending strength of 1231 MPa or more, The peak intensity I of the (101) plane of silicon nitride by X-ray diffraction of the sintered body （１０１） and the peak intensity of the (210) plane I （２１０） Relative to I （１０１） / I （２１０） A ceramic biomaterial characterized by having a structure in which the β-distribution coefficient is 1.3 or more.

10. A biocomponent to be implanted in a living body, comprising the ceramic biomaterial according to any one of claims 1 to 9, A biological component characterized in that the surface roughness (arithmetic mean roughness Sa) of the sliding portion between the biological component and another component is 0.025 μm or less.

11. A method for manufacturing a biocomponent, characterized by mixing a powder of silicon nitride having a total content of unavoidable impurities such as iron and calcium of 300 ppm or less with a powder of a sintering aid, and sintering the mixture at a temperature of 1600 to 1900°C and a pressure of 20 to 35 MPa to produce a sintered body having a bending strength of 1231 MPa or more.

Images