Material for plasma spraying

Abstract

The present application provides a material for plasma spraying that enables formation of a HAp coating film that is high in hardness and less likely to wear even under plasma spraying conditions with low flame energy. The HAp powder has an average particle diameter (D 50 ) of 15 to 40 μm and a pore volume of pores with a pore diameter of 2000 nm or less as measured by mercury porosimetry of 0.01 to 0.30 cc / g. The HAp powder enables plasma spraying even under plasma spraying conditions with low flame energy and enables formation of a HAp coating film that is high in hardness and less likely to wear.

Description

Technical Field

[0001] This invention relates to plasma spraying materials that can form a hydroxyapatite coating with high hardness and resistance to wear even under low flame energy plasma spraying conditions. Background Technology

[0002] Due to aging, the use of implants such as artificial joints and spinal fixation devices is increasing, primarily for fractures and deforming hip joints. Previously, high-strength and stable metallic materials such as titanium alloys and Co-Cr-Ni alloys were commonly used as the base material for these implants. However, while metallic materials possess high strength, they also have drawbacks, including low elasticity which can damage the underlying bone, and low X-ray transmittance which makes diagnosis of bone lesions difficult.

[0003] Therefore, in order to overcome the aforementioned drawbacks of metallic materials, resin materials such as polyetheretherketone (PEEK), which possess strength, elasticity, chemical resistance, and X-ray transmissibility similar to bone, have gradually been used as the base material for implants. However, although PEEK has excellent physical properties, it lacks biological activity and cannot directly bind to biological tissues, thus leading to the problem of loosening in implants based on PEEK.

[0004] To address the aforementioned problems with PEEK-based implants, the following research was conducted: methods for coating PEEK surfaces with bioactive materials and methods for mixing PEEK with bioactive materials to impart biocompatibility (the ability to directly bind to biological tissues). However, in the mixing method, the original physical properties of PEEK cannot be maintained, and the bioactive material cannot be present throughout the entire surface. Therefore, to maintain the original physical properties of PEEK and to achieve biocompatibility throughout the entire surface, the coating method is considered preferable.

[0005] Previously, hydroxyapatite (hereinafter also referred to as HAp) was mainly used as a bioactive material. Methods for coating it, such as plasma spraying, immersion, electrophoresis, and flame spraying, were studied to form the coating. However, considering production efficiency and the availability of equipment, plasma spraying is the most preferred method. Methods for forming HAp coatings on plastic materials such as PEEK using plasma spraying have been previously disclosed (for example, see Patent Document 1, etc.).

[0006] On the other hand, in plasma spraying, when a working gas such as argon is supplied to an electric arc generated by applying a voltage between the cathode and anode, the working gas ionizes. Plasma spraying material is then supplied to the resulting plasma flame, and the temperature and airflow of the plasma flame cause the molten coating material to adhere to the substrate, thereby forming a film. Since the plasma flame reaches approximately 10,000°C, the substrate becomes extremely hot. While the substrate may not decompose due to the flame heat if it is metallic, it can sometimes cause thermal decomposition and thermal degradation if the substrate is made of resin.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: Japanese Patent Application Publication No. 4-146762 Summary of the Invention

[0010] The problem that the invention aims to solve

[0011] When forming a high-hardness HAp coating on resin-based substrates such as PEEK using plasma spraying, it is necessary to reduce the flame energy during plasma spraying to suppress the thermal decomposition and thermal degradation of the resin substrate. However, if the flame energy is reduced, the coating cannot be formed, or the formed coating has insufficient hardness and is easily worn. Therefore, the following problem exists: simply controlling the plasma spraying conditions cannot form a high-hardness HAp coating on resin-based substrates such as PEEK.

[0012] Therefore, the present invention provides a plasma spraying material that can form a high-hardness and wear-resistant HAp coating even under low flame energy plasma spraying conditions.

[0013] Methods for solving problems

[0014] The inventors of this application conducted in-depth research to solve the aforementioned problems and found that, for the average particle size (D) 50 For HAp powder with a pore size of 15–40 μm and a pore volume of 0.01–0.30 cc / g (measured by mercury porosimetry as less than 2000 nm), plasma spraying can be performed even under low flame energy conditions, resulting in a high-hardness and wear-resistant HAp coating. Furthermore, this HAp coating can be formed without causing thermal decomposition or thermal deformation of the resin substrate. This invention was completed based on the above insights and through further repeated research.

[0015] That is, the present invention provides an invention in the manner disclosed below.

[0016] Item 1. A material for plasma sputtering, comprising hydroxyapatite powder, wherein the average particle size (D) of the hydroxyapatite powder is...50 The pore size is 15–40 μm, and the pore volume, measured by mercury porosimetry, is less than 2000 nm and is 0.01–0.30 cc / g.

[0017] Item 2. The plasma sputtering material as described in Item 1, wherein the pore volume is 0.01 to 0.25 cc / g.

[0018] Item 3. The plasma sputtering material as described in Item 1 or 2, wherein the average particle size (D) 50 The value is 20–40 μm.

[0019] Item 4. The plasma sputtering material as described in any one of items 1 to 3, wherein the BET specific surface area of ​​the hydroxyapatite powder is less than 5 m². 2 / g.

[0020] Item 5. The plasma sputtering material as described in any one of Items 1 to 4, wherein the hydroxyapatite powder has a pore volume of 0.20 to 0.80 cc / g at 2000 nm or more as determined by mercury intrusion porosimetry.

[0021] Item 6. The plasma sputtering material as described in any one of Items 1 to 5, used for plasma sputtering in which a gas composed of only one or more monatomic molecules is used as the working gas.

[0022] Item 7. The plasma spraying material as described in any one of items 1 to 6, used to form a coating on a substrate.

[0023] Item 8. The plasma sputtering material as described in Item 7, wherein the material of the substrate is resin, metal, or ceramic.

[0024] Item 9. The plasma sputtering material as described in Item 7 or 8, wherein the material of the substrate is polyetheretherketone.

[0025] Item 10. The plasma sputtering material as described in Item 7 or 8, wherein the material of the substrate is a titanium alloy.

[0026] Item 11. The plasma sputtering material as described in any one of items 7 to 10, wherein the substrate is an implant.

[0027] Item 12. A method for forming a hydroxyapatite coating, wherein the material for plasma sputtering as described in any one of Items 1 to 11 is subjected to plasma sputtering to form a hydroxyapatite coating on a substrate.

[0028] Item 13. The method for forming a hydroxyapatite coating as described in Item 12, wherein the material of the substrate is a resin, a metal, or a ceramic.

[0029] Item 14. The method for forming a hydroxyapatite coating as described in Item 12 or 13, wherein the material of the substrate is polyetheretherketone.

[0030] Item 15. The method for forming a hydroxyapatite coating as described in Item 12 or 13, wherein the material of the substrate is a titanium alloy.

[0031] Item 16. A method for forming a hydroxyapatite coating as described in any one of items 12 to 15, wherein the substrate is an implant.

[0032] Item 17. Use of hydroxyapatite powder as a material for plasma sputtering, wherein the average particle size (D) of the hydroxyapatite powder is... 50 The pore size is 15–40 μm, and the pore volume, measured by mercury porosimetry, is less than 2000 nm and is 0.01–0.30 cc / g.

[0033] The effects of the invention

[0034] According to the plasma sputtering material of the present invention, plasma sputtering can be performed even under low flame energy conditions, and a high-hardness and wear-resistant HAp coating can be formed. Therefore, by using the plasma sputtering material of the present invention to perform plasma sputtering on resin substrates such as PEEK with low flame energy, the thermal decomposition and thermal degradation of the resin substrate can be suppressed.

[0035] While not intended to be limiting, it is presumed that in the plasma sputtering material of the present invention, by limiting the average particle size of the HAp powder used, the particles can be melted entirely using low flame energy. Furthermore, because the pore volume (measured by mercury porosimetry as less than 2000 nm) is limited to a small range, there are fewer voids within the particles, thus heat conduction to the particle interior is not blocked, and the heat from the plasma flame is easily conducted to the entire particle, resulting in higher impact energy on the substrate. It is believed that the plasma sputtering material of the present invention, based on these characteristics, can meet the performance requirements under low flame energy plasma sputtering conditions. Attached Figure Description

[0036] Figure 1-1 Images of the appearance of the HAp powders from Examples 1 to 4 are shown under a microscope.

[0037] Figure 1-2 Images of the appearance of HAp powder from Examples 5-6 and Comparative Example 1 are shown under a microscope.

[0038] Figure 1-3 Images of the appearance of HAp powder from Comparative Examples 2-7 are shown under a microscope.

[0039] Figure 2-1 The images shown are obtained by microscopic observation of the cross-sectional appearance of the HAp coating formed by plasma sputtering of the HAp powders of Examples 1 to 4.

[0040] Figure 2-2 The images shown are obtained by microscopic observation of the cross-sectional appearance of the HAp coating formed by plasma sputtering of HAp powders from Examples 5-6 and Comparative Example 5.

[0041] Figure 3 The results show the pore size distribution of HAp powders from Examples 1 and 2 determined by mercury intrusion porosimetry.

[0042] Figure 4 The results show the pore size distribution of the HAp powders in Examples 3 and 4 determined by mercury intrusion porosimetry.

[0043] Figure 5 The results of determining the pore size distribution of HAp powders from Comparative Examples 1 to 3 by mercury intrusion porosimetry are shown.

[0044] Figure 6 The results of determining the pore size distribution of HAp powders in Comparative Examples 4 and 5 by mercury intrusion porosimetry are shown.

[0045] Figure 7 The results of determining the pore size distribution of HAp powders in Comparative Examples 6 and 7 by mercury intrusion porosimetry are shown.

[0046] Figure 8 The results of fine pore size distribution of HAp powders in Examples 5 and 6 by mercury intrusion porosimetry are shown.

[0047] Figure 9 The results of powder X-ray diffraction analysis of the HAp powder of Example 1 are shown. Detailed Implementation

[0048] The plasma sputtering material of the present invention is characterized by containing an average particle size (D) 50 The HAp powder has a pore size of 15–40 μm and a pore volume of 0.01–0.30 cc / g with a pore diameter of less than 2000 nm as determined by mercury porosimetry. The plasma sputtering material of the present invention will be described in detail below.

[0049] [Physical properties of HAp powder]

[0050] HAp is calcium phosphate represented by the chemical formula Ca5(PO4)3(OH).

[0051] The average particle size (D) of the HAp powder used in this invention 50The average particle size (D) of the HAp powder used in this invention is 15–40 μm. 50 The preferred particle size (D) is 20–40 μm, more preferably 20–30 μm, further preferably 25–30 μm, and particularly preferably 26–30 μm. It should be noted that in this invention, "average particle size (D)" refers to the particle size distribution. 50 "" refers to the particle size (median particle size) in the volume cumulative reference particle size distribution measured using a laser diffraction-scattering particle size distribution measuring device, where the cumulative frequency reaches 50%.

[0052] D for the HAp powder used in this invention 90 To meet the aforementioned average particle size (D) 50 The range of ) is limited and not particularly restricted; for example, 30–70 μm, preferably 35–55 μm, and more preferably 41–47 μm. It should be noted that in this invention, "D" 90 "" refers to the particle size in the cumulative reference particle size distribution measured using a laser diffraction-scattering particle size distribution measuring device, where the cumulative frequency reaches 90%.

[0053] D for the HAp powder used in this invention 10 To meet the aforementioned average particle size (D) 50 The range of ) is limited and not particularly restricted; for example, 7–30 μm, preferably 10–25 μm, and more preferably 14–19 μm. It should be noted that in this invention, "D" 10 "" refers to the particle size in the cumulative reference particle size distribution measured using a laser diffraction-scattering particle size distribution measuring device, where the cumulative frequency reaches 10%.

[0054] In the HAp powder used in this invention, the pore volume with a pore size of 2000 nm or less, as measured by mercury intrusion porosimetry, is 0.01 to 0.30 cc / g. By satisfying the aforementioned range of average particle size and this range of pore volume, plasma spraying can be performed even under plasma spraying conditions using low flame energy, and a HAp coating with high hardness and wear resistance can be formed. From the viewpoint of further improving the hardness and wear resistance of the HAp coating formed under plasma spraying conditions using low flame energy, the pore volume with a pore size of 2000 nm or less, as measured by mercury intrusion porosimetry, is preferably 0.01 to 0.25 cc / g, more preferably 0.01 to 0.23 cc / g, and even more preferably 0.01 to 0.22 cc / g.

[0055] In this invention, "pore volume with a pore size of less than 2000 nm as determined by mercury porosimetry" refers to the cumulative pore volume of the region with a pore size of less than 2000 nm within the pore volume measured using a mercury porosimetry instrument in water. In this pore volume measurement, the mercury contact angle is set to 140° and the surface tension of mercury is set to 480 erg / cm for the mercury porosimetry instrument. 2 .

[0056] In the HAp powder used in this invention, there is no particular limitation on the pore volume with a pore size of 2000 nm or more as determined by mercury porosimetry. Examples include 0.20 to 0.80 cc / g, preferably 0.30 to 0.75 cc / g, and more preferably 0.35 to 0.70 cc / g.

[0057] In this invention, "pore volume with a pore size of 2000 nm or more as measured by mercury porosimetry" refers to the cumulative pore volume of the region with a pore size of 2000 nm or more in the pore volume measured using a mercury porosimeter. The conditions for measuring this pore volume are the same as those for the aforementioned "pore volume with a pore size of less than 2000 nm".

[0058] In the HAp powder used in this invention, there is no particular limitation on the mode diameter of the pore size of less than 2000 nm as determined by mercury intrusion porosimetry. Examples include 3 to 1000 nm, preferably 4 to 750 nm, and more preferably 5 to 500 nm.

[0059] In this invention, "the mode diameter with a pore size of less than 2000 nm as determined by mercury porosimetry" refers to the diameter (most frequent pore diameter) that appears most frequently in the region with a pore size of less than 2000 nm in the pore distribution measured using a mercury porosimeter. The conditions of the mercury porosimeter used in determining this mode diameter are the same as those for "pore volume with a pore size of less than 2000 nm" mentioned above.

[0060] In the HAp powder used in this invention, there is no particular limitation on the mode diameter of the pore size of 2000 nm or more as determined by mercury intrusion porosimetry. Examples include 2000–15000 nm, preferably 5000–13000 nm, more preferably 7500–13000 nm, and particularly preferably 8000–11000 nm.

[0061] In this invention, "the mode diameter with a pore size of 2000 nm or more as determined by mercury porosimetry" refers to the diameter (most frequent pore diameter) that appears most frequently in the region with a pore size of 2000 nm or more in the pore distribution measured using a mercury porosimetry instrument. In the determination of this mode diameter, the conditions of the mercury porosimetry instrument are the same as those for the aforementioned "pore volume with a pore size of less than 2000 nm".

[0062] In the HAp powder used in this invention, there is no particular limitation on the pore volume determined by the gas adsorption method. For example, 0.0001 to 0.01 cc / g, preferably 0.0005 to 0.005 cc / g, and more preferably 0.001 to 0.003 cc / g are examples.

[0063] In this invention, "pore volume determined by gas adsorption method" refers to the value measured using a high-speed specific surface area pore distribution measuring device and the following method. First, accurately weigh 1.0–2.0 g of HAp powder, seal it in an adsorption tube, and degas it at 105°C for 3 hours. Then, determine the adsorption isotherm of nitrogen gas at liquid nitrogen temperature, and calculate the total pore volume (cc / g) based on the amount of gas adsorbed when the liquid relative pressure P / P0 (P0: saturated vapor pressure) is 0.995.

[0064] Furthermore, in the HAp powder used in this invention, there is no particular limitation on the average pore size measured by the gas adsorption method; for example, 5 to 1000 nm, preferably 8 to 700 nm, and more preferably 10 to 550 nm are examples.

[0065] In this invention, "average pore size determined by gas adsorption method" refers to the value calculated according to the following formula.

[0066] Average pore size (nm) = 4V / S × 1000

[0067] V: Pore volume (cc / g) determined by gas adsorption method

[0068] S: BET specific surface area (m²) 2 / g)

[0069] Furthermore, there are no particular limitations on the bulk density of the HAp powder used in this invention. For example, 0.1 to 3.0 g / mL, preferably 0.4 to 2.0 g / mL, and more preferably 0.6 to 1.1 g / mL are examples.

[0070] In this invention, "volume density" refers to the relaxed volume density determined based on the test method specified in ASTM B212.

[0071] There are no particular limitations on the BET specific surface area of ​​the HAp powder used in this invention; for example, it can be less than 5 m². 2 / g, preferably 0-2m 2 / g, more preferably 0-1m 2 / g.

[0072] In this invention, "BET specific surface area" refers to the value measured using a high-speed specific surface area fine pore distribution measuring device and the following method. First, accurately weigh 1.0–2.0 g of HAp powder, seal it in an adsorption tube, and degas it at 105°C for 3 hours. Then, determine the adsorption isotherm of nitrogen gas at liquid nitrogen temperature, and use this adsorption isotherm to calculate the specific surface area (m²) using the multi-point BET method. 2 / g).

[0073] There are no particular limitations on the angle of repose of the HAp powder used in this invention; for example, 20–90°, preferably 40–70°, and more preferably 40–60° are examples. In order to have such an angle of repose, the particle shape of the HAp powder is preferably spherical, substantially spherical, etc.

[0074] In this invention, the "angle of repose" refers to the value measured using the injection method, with the vibration time set to 30 seconds and the amplitude set to 0.5 mm.

[0075] There are no particular limitations on the particle hardness of the HAp powder used in this invention; for example, 100 to 15000 gf / mm can be cited. 2 Preferably, it is 500–10000 gf / mm 2 More preferably, it is 800–8000 gf / mm 2 .

[0076] In this invention, the “particle hardness” of HAp powder refers to the value obtained by using a particle hardness measuring device, setting the measuring speed to 10 μm / s, setting the maximum detection reduction rate to 80% (the threshold obtained by reading the peak value; when the load decreases by 20% from the previous peak value, the previous peak value is detected as the maximum value), setting the sample stage detection load (as a roughly standard load used to detect the origin position) to 10.0 gf, and performing 10 measurements, and calculating the average value.

[0077] [Method for manufacturing HAp powder]

[0078] The method for manufacturing HAp powder used in this invention is limited to obtaining HAp powder with the aforementioned physical properties, and is not particularly limited. As a preferred example, a manufacturing method including the following steps 1 to 5 can be cited.

[0079] Step 1: HAp is generated by either (1) a wet process comprising a step of adding phosphoric acid dropwise to a suspension obtained by suspending calcium hydroxide, or (2) a wet process comprising a step of adding a suspension obtained by suspending calcium hydroxide to an aqueous solution of phosphoric acid obtained by dissolving phosphoric acid in water.

[0080] Step 2: The Hap obtained in Step 1 above is subjected to wet pulverization to obtain the wet pulverized HAp.

[0081] Step 3: The wet-pulverized HAp obtained in Step 2 above is dried to obtain dry HAp powder.

[0082] Step 4: The dried HAp powder obtained in Step 3 above is calcined at a temperature greater than 1050°C and less than 1400°C.

[0083] Step 5: The calcined HAp powder obtained in Step 4 above is sieved to recover the average particle size (D). 50 ) is HAp powder with a size of 15-40 μm.

[0084] In the first step, calcium ions react with phosphate ions to carry out the HAP synthesis reaction [10Ca(OH)2 + 6H3PO4 → Ca] by (1) adding phosphoric acid dropwise to a suspension obtained by suspending calcium hydroxide, or (2) adding a suspension obtained by suspending calcium hydroxide to a phosphoric acid aqueous solution obtained by dissolving phosphoric acid in water. 10 [(PO4)6(OH)2] is sufficient. In the first step described above, the ratio of calcium hydroxide to phosphoric acid in the final coexisting state can be adjusted to be the same as the ratio of calcium to phosphorus in HAp. For the liquid obtained by suspending calcium hydroxide in water to form an emulsion, it can be obtained by adding calcium oxide to water to allow it to undergo a hydration reaction. In addition, when adding phosphoric acid dropwise to the suspension obtained by suspending calcium hydroxide, the added phosphoric acid is preferably in the form of an aqueous solution of phosphoric acid obtained by dissolving phosphoric acid in water. When adding phosphoric acid dropwise to the suspension obtained by suspending calcium hydroxide, the rate of phosphoric acid addition can be appropriately adjusted so that the pH of the reaction solution after addition is 9 or less. For example, the phosphorus (P) atoms can reach a range of 0.05 to 0.6 mol / h relative to 1 mol of calcium (Ca) atoms, preferably a range of 0.1 to 0.3 mol / h, and more preferably a range of 0.2 mol / h. Furthermore, if a suspension obtained by suspending calcium hydroxide is added to an aqueous solution of phosphoric acid obtained by dissolving phosphoric acid in water, the calcium (Ca) atom concentration can reach 0.05 to 0.6 mol / h relative to 1 mol of phosphorus (P) atoms.

[0085] Furthermore, in the first step, the temperature (reaction temperature) at which calcium ions react with phosphate ions can be appropriately set according to the amount of water added, the dropping rate, etc. For example, a range of 20°C or higher is acceptable, a range of 30 to 70°C is preferred, and a range of 40 to 60°C is more preferable. To further efficiently react calcium ions with phosphate ions and generate a reaction solution, it is desirable to allow the calcium and phosphate ions to coexist completely under the aforementioned temperature conditions. In this invention, aging refers to a certain period of time under stillness or stirring. The aging time can be appropriately set according to the amount of water added, the dropping rate, the reaction temperature, etc. For example, a range of 0 minutes or higher is acceptable, a range of 0.5 to 5 hours is preferred, and a range of 1 to 3 hours is more preferable. Here, "aging time" refers to the time under stillness or stirring when the time when all calcium and phosphate ions coexist in the water is set to 0 minutes. For example, if phosphoric acid is added dropwise to a suspension obtained by suspending calcium hydroxide, the time calculated is the time calculated when the time when the phosphoric acid addition ends is set to 0 minutes.

[0086] It should be noted that if HAp is synthesized by a wet method in which a suspension obtained by simultaneously suspending calcium hydroxide is mixed with phosphoric acid, the aforementioned physical properties cannot be obtained, and thus HAp suitable for plasma spraying cannot be formed.

[0087] From the viewpoint of efficiently manufacturing the HAp powder used in this invention, the first step is preferably carried out by a wet method including a step of adding phosphoric acid dropwise to a suspension obtained by suspending calcium hydroxide.

[0088] By performing the first step in this way, the reaction solution for generating HAp can be obtained.

[0089] In the second step, the Hap obtained in the first step is wet-milled to obtain a wet-milled HAp product.

[0090] In the second step, the reaction liquid after the first step can be directly supplied to the wet mill, or the concentrated liquid obtained by concentrating the reaction liquid after the first step, or the suspension obtained by recovering Hap from the reaction liquid after the first step and resuspending it in organic solvents such as water and alcohol, can be supplied to the wet mill.

[0091] In the second step, there are no particular restrictions on the wet grinding method; for example, any method can be used, such as impact, shearing, grinding, compression, vibration, etc. Furthermore, there are no particular restrictions on the type of wet grinding equipment; for example, it can be any device such as a high-pressure fluid impact mill, a high-speed rotary slot mill, a grinder, a ball mill, a bead mill, a roller mill, a ring grinding media mill, a high-speed rotary thin film mill, etc. Known or commercially available equipment can be used. Among these wet grinding devices, bead mills are preferred.

[0092] When using a bead mill as a wet grinding device, there are no particular restrictions on the type of grinding beads, but beads made of zirconia-based materials are preferred. The size of the grinding beads can be, for example, approximately 0.1 to 3 mm in diameter. The filling amount of the grinding beads can be appropriately set according to the size of the device used, for example, within a range of approximately 50 to 90% by volume.

[0093] In the second step, the degree of wet grinding can be appropriately adjusted. From the viewpoint of efficiently manufacturing HAp powder with the aforementioned properties, it is desirable that the wet-ground HAp particles be adjusted in the following manner: the average particle size reaches 10 μm or less, preferably 5 μm or less, the maximum particle size reaches 100 μm or less, preferably 30 μm or less, and more preferably the average particle size reaches 1 to 3 μm and the maximum particle size reaches 20 μm or less. In this invention, the "average particle size" and "maximum particle size" of the wet-ground HAp particles refer to the median particle size (D50) and maximum particle size measured using a laser diffraction-scattering particle size distribution measuring device, respectively.

[0094] In the third step, the wet-pulverized HAp obtained in the second step is dried to obtain dried HAp powder. There are no particular limitations on the drying method used in the third step; examples include spray drying, box drying, belt drying, vacuum drying, freeze drying, microwave drying, drum drying, and flow drying.

[0095] From the viewpoint of drying the spherical particles and giving them a shape preferred for use as a material in plasma spraying, spray drying is preferred. The conditions for spray drying are limited to obtaining an HAP with the aforementioned physical properties, and are not particularly limited. For example, setting the inlet temperature to 200–500°C, the outlet temperature to 100–200°C, and the disk rotation speed to 5000–30000 rpm is sufficient.

[0096] In the fourth step, the dried HAp powder obtained in the third step is calcined at a temperature greater than 1050°C and less than 1400°C. Conventionally, the calcination of HAp powder manufactured by the wet method is generally carried out at temperatures below 1000°C, but HAp powder possessing the aforementioned properties cannot be obtained under such temperature conditions. In the fourth step, by setting the calcination temperature of the HAp powder manufactured in the third step to a temperature greater than 1050°C and less than 1400°C, HAp powder possessing the aforementioned properties can be obtained. Preferably, the calcination temperature in the fourth step is greater than 1050°C to 1350°C, and more preferably 1100°C to 1300°C.

[0097] Furthermore, regarding the holding time of the firing temperature conditions in the fourth step, taking into account the temperature conditions, it is acceptable to set it appropriately within the range of generating HAp powder with the aforementioned physical properties. It is also possible to reach the aforementioned firing temperature conditions instantaneously. Examples of preferred values ​​are 0.1 to 10 hours, and more preferably 1 to 5 hours.

[0098] In step 5, the calcined HAp powder obtained in step 4 is sieved to recover the average particle size (D). 50 The HAp powder is 15–40 μm. The mesh size of the sieve used in step 5 is adjusted to allow for the recovery of the average particle size (D). 50 The HAp powder is limited to 15-40 μm, but there is no particular limitation. Examples include 500 μm or less, preferably 20-500 μm, and more preferably 30-50 μm.

[0099] By performing the fifth step in this way, HAp powder (the HAp powder used in this invention) with the aforementioned physical properties can be obtained.

[0100] Furthermore, the HAp powder used in this invention can also be obtained by separating HAp powder with the aforementioned physical properties from HAp powder manufactured by methods other than the manufacturing methods of the first to fifth steps described above, using methods such as sieving.

[0101] [Purpose and Usage]

[0102] In this invention, the aforementioned HAp powder is used as a material for plasma sputtering. "Material for plasma sputtering" refers to powder supplied for plasma sputtering (powder that serves as the material for the formed coating). Furthermore, "plasma sputtering" refers to a technique that uses plasma to heat the material (powder) for plasma sputtering, causing it to melt and form liquid particles, which are then collide at high speed with the surface of a substrate along with a plasma jet, thereby forming a coating of the material for plasma sputtering on the substrate.

[0103] In plasma sputtering using the plasma sputtering material of the present invention, there are no particular limitations on the material of the substrate to which the HAp coating is formed. Examples include resins such as PEEK, polyethylene, polyester, polypropylene, polyamide, polyether, polyetherketone, acrylic acid, polystyrene, polytetrafluoroethylene, hydroxyethyl methacrylate, polyamide, polylactic acid, polyglycolic acid, polylactide, polyglycolic acid, polydioxanone, trimethylene carbonate, and ε-caprolactone; titanium alloys (Ti-6Al-4V alloy, Ni-Ti, etc.), cobalt alloys (Co-Cr-Ni alloy, Co-Cr-Mo, Co-Cr-W-Ni, etc.), magnesium alloys (Mg-Y-RE, Mg-Ca-Zn, Mg-Li-Al, etc.), stainless steel (SUS316L, SUS304, etc.), titanium, cobalt, molybdenum, niobium, tantalum, gold, platinum, tungsten, iridium, and Inconel; and ceramics such as alumina and zirconium oxide. The plasma spraying material of the present invention is characterized by its ability to perform plasma spraying under low flame energy conditions and to form a high-hardness, wear-resistant HAp coating. By employing low flame energy plasma spraying conditions, thermal decomposition and thermal degradation of resin-based substrates can be suppressed. In view of these effects of the present invention, resins (especially PEEK) are preferred examples of materials for substrates to which HAp coatings are formed.

[0104] Furthermore, there are no particular limitations on the type (use) of the substrate to which the HAp coating is formed. Examples include implants such as artificial joints, artificial tooth roots, and artificial bones; and housings of intraocular implantable devices such as assistive artificial hearts, artificial blood vessels, stents, pacemakers, sutures, catheters, artificial skin, artificial muscles, and intraocular lenses. Implants (especially artificial joints) are easily subjected to stress within the body, thus requiring the HAp coating applied to the substrate to possess high hardness and wear resistance. The plasma-spraying material of the present invention can form an HAp coating that meets the aforementioned required characteristics of implants (especially artificial joints), and is therefore preferably used as a forming material for HAp coatings applied to the surface of implants (especially artificial joints).

[0105] There are no particular restrictions on the plasma sputtering conditions when forming an HAp coating on a substrate using the plasma sputtering material of the present invention. As long as the conditions are set appropriately within the range of commonly used plasma sputtering conditions, depending on the type of substrate and the thickness of the HAp coating to be formed.

[0106] Furthermore, as described above, the plasma sputtering material of the present invention is characterized by its ability to perform plasma sputtering even under low flame energy conditions and to form a high-hardness, wear-resistant HAp coating. Therefore, as a preferred example of plasma sputtering for the application of the plasma sputtering material of the present invention, plasma sputtering conditions with low flame energy can be cited. Specific examples of low flame energy plasma sputtering conditions include using a gas with a high ratio of monatomic molecules, such as argon or helium, as the working gas in plasma sputtering. Since monatomic molecules such as argon and helium retain lower energy than diatomic molecules such as hydrogen, nitrogen, and oxygen, using a gas with a high ratio of monatomic molecules as the working gas can lower the flame energy during plasma sputtering, thereby achieving plasma sputtering conditions that can suppress the thermal decomposition and thermal degradation of resin-based substrates such as PEEK. More specifically, as a working gas for reducing flame energy, a gas composed of only one or more monatomic molecules can be cited, preferably a mixture of argon and helium.

[0107] Example

[0108] The following examples illustrate the invention in more detail, but the invention is not limited thereto.

[0109] 1. Manufacturing of materials for plasma sputtering (HAp powder)

[0110] Example 1

[0111] Add 6 L of water and 1 kg of calcium oxide to the reaction vessel to allow for hydration. Then, add water to the suspension to adjust the total volume to 15 L. Next, heat to 50 °C and add an aqueous phosphoric acid solution at a dropping rate of 0.2 mol / h relative to 1 mol of calcium (Ca) atoms until the pH reaches 8. Heat the resulting solution to 95 °C and allow it to react for 2 hours.

[0112] Then, the obtained reaction solution was wet-milled using 1 mm diameter zirconia grinding beads (grinding bead filling amount 70% (v / v)) to achieve an average particle size of 2 μm and a maximum particle size of 15 μm. After obtaining the wet-milled material, it was spray-dried using a spray dryer with a disc spray mechanism at an inlet temperature of 300°C, an outlet temperature of 130°C, and a disc rotation speed of 16000 rpm, and the dried material was recovered.

[0113] Furthermore, the obtained dried material was calcined at 1220°C for 3 hours using an electric furnace (Kusaba Chemical Co., Ltd.) (heating rate 65°C / h). After cooling, it was sieved using a benchtop vibrating sieve (VSS-200S type, Tsutsui Rikkyo Equipment Co., Ltd.) according to condition A as described in Table 1, and the sieved powder was recovered to obtain HAp powder.

[0114] Example 2

[0115] The firing temperature was changed to 1300°C, and HAp powder was obtained under the same conditions as in Example 1.

[0116] Example 3

[0117] The firing temperature was changed to 1150°C, and HAp powder was obtained under the same conditions as in Example 1.

[0118] Example 4

[0119] Add 6 L of water and 1 kg of calcium oxide to the reaction vessel to allow for hydration. Then, add water to the suspension to adjust the total volume to 15 L. Next, heat to 50 °C and add an aqueous phosphoric acid solution at a dropping rate of 0.2 mol / h relative to 1 mol of calcium (Ca) atoms until the pH reaches 8. Heat the resulting solution to 95 °C and allow it to react for 2 hours.

[0120] Then, the obtained reaction liquid was spray-dried using a spray dryer equipped with a disc spray mechanism at an inlet temperature of 300°C, an outlet temperature of 130°C, and a disc rotation speed of 10,000 rpm, and the dried material was recovered.

[0121] Furthermore, the obtained dried material was calcined at 1150°C for 3 hours using an electric furnace (Kusaba Chemical Co., Ltd.) (heating rate 65°C / h). After cooling, it was sieved using a benchtop vibrating sieve (VSS-200S type, Tsutsui Rikkyo Equipment Co., Ltd.) according to condition B described in Table 1, and the sieved powder was recovered to obtain HAp powder.

[0122] Example 5

[0123] The HAp powder obtained in Example 1 was sieved using a benchtop vibrating sieve (VSS-200S type, Tsutsui Rikkyo Equipment Co., Ltd.) under condition C as described in Table 1, and the sieved powder was recovered to obtain HAp powder.

[0124] Example 6

[0125] The HAp powder obtained in Example 1 was sieved using a benchtop vibrating sieve (VSS-200S type, Tsutsui Rikkyo Equipment Co., Ltd.) under condition C as described in Table 1, and the powder remaining on the sieve was recovered to obtain HAp powder.

[0126] Comparative Example 1

[0127] Add 6 L of water and 1 kg of calcium oxide to the reaction vessel to allow for hydration. Then, add water to the suspension to adjust the total volume to 15 L. Next, heat to 50 °C and add an aqueous phosphoric acid solution at a dropping rate of 0.2 mol / h relative to 1 mol of calcium (Ca) atoms until the pH reaches 8. Heat the resulting solution to 95 °C and react for 2 hours.

[0128] Then, the obtained reaction liquid was spray-dried using a spray dryer equipped with a disc spray mechanism at an inlet temperature of 300°C, an outlet temperature of 130°C, and a disc rotation speed of 11,000 rpm, and the dried material was recovered.

[0129] Furthermore, the obtained dried material was calcined in an electric furnace (Kusaba Chemical Co., Ltd.) at 800°C for 3 hours (heating rate 65°C / h). After cooling, HAp powder was obtained.

[0130] Comparative Example 2

[0131] Use commercially available HAp powder (Medicoat's Hydroxyapatite (Medipure 20-15 No. 101)).

[0132] Comparative Example 3

[0133] Add 6 L of water and 1 kg of calcium oxide to the reaction vessel to allow for hydration. Then, add water to the suspension to adjust the total volume to 15 L. Next, heat to 50 °C and add phosphoric acid solution at a dropping rate of 0.2 mol / h relative to 1 mol of calcium (Ca) atoms until the pH reaches 8. Heat the resulting solution to 95 °C and allow it to react for 2 hours.

[0134] Then, the obtained reaction liquid was spray-dried using a spray dryer equipped with a disc spray mechanism at an inlet temperature of 300°C, an outlet temperature of 130°C, and a disc rotation speed of 10,000 rpm, and the dried material was recovered.

[0135] Furthermore, the obtained dried material was calcined in an electric furnace (Kusaba Chemical Co., Ltd.) at 1150°C for 3 hours (heating rate 65°C / h). After cooling, HAp powder was obtained.

[0136] Comparative Example 4

[0137] Use commercially available HAp powder (Medicoat's hydroxyapatite (Medipure 20-15 No. 102)).

[0138] Comparative Example 5

[0139] Add 6 L of water and 1 kg of calcium oxide to the reaction vessel to allow for hydration. Then, add water to the suspension to adjust the total volume to 15 L. Next, heat to 50 °C and add phosphoric acid solution at a dropping rate of 0.2 mol / h relative to 1 mol of calcium (Ca) atoms until the pH reaches 8. Heat the resulting solution to 95 °C and allow it to react for 2 hours.

[0140] Then, the obtained reaction liquid was spray-dried using a spray dryer equipped with a disc spray mechanism at an inlet temperature of 300°C, an outlet temperature of 130°C, and a disc rotation speed of 11,000 rpm, and the dried material was recovered.

[0141] Furthermore, the obtained dried material was calcined at 800°C for 3 hours using an electric furnace (Kusaba Chemical Co., Ltd.) (heating rate 65°C / h). After cooling, it was sieved using a benchtop vibrating sieve (VSS-200S type, Tsutsui Rikkyo Equipment Co., Ltd.) according to condition D as described in Table 1, and the sieved powder was recovered to obtain HAp powder.

[0142] Comparative Example 6

[0143] Add 6 L of water and 1 kg of calcium oxide to the reaction vessel to allow for hydration. Then, add water to the suspension to adjust the total volume to 15 L. Next, heat to 50 °C and add phosphoric acid solution at a dropping rate of 0.2 mol / h relative to 1 mol of calcium (Ca) atoms until the pH reaches 8. Heat the resulting solution to 95 °C and allow it to react for 2 hours.

[0144] Then, the obtained reaction solution was wet-milled using 1 mm diameter zirconia grinding beads (grinding bead filling amount 70% (v / v)) to achieve an average particle size of 2 μm and a maximum particle size of 15 μm. After obtaining the wet-milled material, it was spray-dried using a spray dryer with a disc spray mechanism at an inlet temperature of 300°C, an outlet temperature of 130°C, and a disc rotation speed of 16000 rpm, and the dried material was recovered.

[0145] Furthermore, the obtained dried material was calcined at 1180°C for 3 hours using an electric furnace (Kusaba Chemical Co., Ltd.) (heating rate 65°C / h). After cooling, it was sieved using a benchtop vibrating sieve (VSS-200S type, Tsutsui Rikkyo Equipment Co., Ltd.) according to condition D as described in Table 1, and the powder on the sieve was recovered to obtain HAp powder.

[0146] Comparative Example 7

[0147] Under pH 7 conditions, 2.5 L of a 25 wt% calcium hydroxide suspension and 1 L of a 50 wt% phosphoric acid solution were simultaneously added dropwise to 5 L of water over 3 hours.

[0148] Then, the obtained reaction liquid was spray-dried using a spray dryer equipped with a disc spray mechanism at an inlet temperature of 300°C, an outlet temperature of 130°C, and a disc rotation speed of 10,000 rpm, and the dried material was recovered.

[0149] Furthermore, the obtained dried material was calcined in an electric furnace (Kusaba Chemical Co., Ltd.) at 1200°C for 3 hours (heating rate 65°C / h). After cooling, HAp powder was obtained.

[0150] Sieving conditions

[0151] The sieving conditions used in the manufacture of the HAp powders in Examples 1 to 6 and Comparative Examples 5 to 6 are shown in Table 1.

[0152] Table 1

[0153] Condition A Condition B Condition C Condition D Screen mesh diameter 45μm 45μm 45μm 45μm <![CDATA[Sieving numbers #1 > 1 1 2 1 Input 50g 50g 100g 50g Vibration time 180 seconds 180 seconds 10 seconds 180 seconds <![CDATA[Vibration intensity #2 > 5 5 5 5 sieve diameter 20cm 20cm 20cm 20cm <![CDATA[Screening times #3 > 3 10 1 3

[0154] #1 Sieve number refers to the number of sieves used. That is, for example, in condition A, one sieve with a mesh size of 45μm is used. In addition, in condition C, two sieves with a mesh size of 45μm are used in an overlapping manner to collect the powder remaining on the two sieves and mix them to obtain HAp powder.

[0155] #2 vibration intensity is the vibration intensity set in the benchtop vibrating screen (VSS-200S type, Tsutsui Rikikaku Equipment Co., Ltd.).

[0156] #3 Sieving count refers to the number of times sieving is performed under each condition. For example, in condition A, it means that after a 180-second vibration period, sieving is repeated twice more under the same conditions, for a total of three sieving operations (total vibration time is 540 seconds). It should be noted that during repeated sieving, no powder is replenished, and no powder that has already passed through the sieve is returned to the sieve.

[0157] 2. Evaluation methods for materials used in plasma sputtering

[0158] 2-1. Material property evaluation for plasma sputtering

[0159] For each HAp powder of Examples 1-6 and Comparative Examples 1-7, the following methods were used to evaluate the bulk density, particle size distribution, mode diameter of pores less than 2000 nm / greater than 2000 nm and pore volume (mercury porosimetry), BET specific surface area, pore volume (gas adsorption method), average pore diameter (gas adsorption method), crystallinity, angle of repose, particle hardness, and appearance.

[0160] Bulk density

[0161] The bulk density (relaxed bulk density) is determined based on the test method specified in ASTM B212.

[0162] Particle size distribution

[0163] HAp powder was dispersed in water, and the particle size distribution was measured using a laser diffraction and scattering particle size distribution measuring device (MicrotracBEL Co., Ltd. "MICROTRAC MT3300EXII") to determine D10, D50 (average particle size) and D90.

[0164] Mode diameter and pore volume of pores smaller than 2000 nm and larger than 2000 nm (mercury porosimetry)

[0165] The mode diameter and pore volume were determined using a mercury porosimeter (Quantachrome Corporation, "poremaster60GT") under the following conditions: 0.1–1.0 g of HAp powder was sealed into the measuring chamber; the mercury contact angle was set to 140°; and the surface tension of the mercury was set to 480 erg / cm. 2 The mode diameter and pore volume are calculated from the measured pressure. It should be noted that the analytical range is divided into two categories: pore diameters below 2000 nm and pore diameters above 2000 nm.

[0166] BET specific surface area

[0167] The BET specific surface area was determined using a high-speed specific surface area pore distribution measuring device (Quantachrome Corporation "NOVA-4000") under the following operating conditions. Pretreatment: Accurately weigh 1.0–2.0 g of HAp powder, seal it in an adsorption tube, and degas at 105 °C for 3 hours.

[0168] Measurement and Analysis: The adsorption isotherm of nitrogen gas was determined at liquid nitrogen temperature. Using this adsorption isotherm, the specific surface area (m²) was calculated using the multi-point BET method. 2 / g).

[0169] Micropore volume (gas adsorption method)

[0170] The pore volume of the gas adsorption method was determined using a high-speed specific surface area pore distribution measuring device (Quantachrome Corporation "NOVA-4000") under the following operating conditions.

[0171] Pretreatment: Accurately weigh 1.0-2.0 g of HAp powder, seal it in an adsorption tube, and degas at 105°C for 3 hours.

[0172] Measurement and analysis: The adsorption isotherm of nitrogen gas was determined at liquid nitrogen temperature, and the total micropore volume (cc / g) was calculated from the amount of gas adsorbed when the relative pressure P / P0 (P0: saturated vapor pressure) was 0.995.

[0173] Average pore size (gas adsorption method)

[0174] The average pore size is calculated using the following formula (gas adsorption method).

[0175] Average pore size (nm) = 4V / S × 1000

[0176] V: Pore volume (gas adsorption method) (cc / g)

[0177] S: BET specific surface area (m²) 2 / g)

[0178] Degree of crystallinity

[0179] HAp powder (test sample) and a sample obtained by treating HAp powder at 1000℃ for 15 hours (pretreated sample) were used to measure the diffraction pattern in the range of 2θ = 25–50° using an X-ray diffraction apparatus "SmartLab" (Rigaku Corporation) (measurement conditions: target: Cu, tube voltage: 40kV, tube current: 30mA, scanning range: 25–50°, scanning speed: 1.000° / min, scanning step: 0.02°, scanning mode: continuous). The diffraction angle (θ) corresponding to the interplanar spacing (d) shown in Table 2 was calculated using the Bragg formula d = λ / 2sinθ. For the diffraction peak with this diffraction angle (2θ) as the peak position, the ratio of the integral intensity of each peak of the test sample to the integral intensity of each peak of the pretreated sample was calculated.

[0180] Table 2

[0181] Interplanar spacing (d) <![CDATA[d1=3.44×10 -10 m]]> <![CDATA[d2=3.17×10 -10 m]]> <![CDATA[d3=3.08×10 -10 m]]> <![CDATA[d4=2.81×10 -10 m]]> <![CDATA[d5=2.78×10 -10 m]]> <![CDATA[d6=2.72×10 -10 m]]> <![CDATA[d7=2.63×10 -10 m]]> <![CDATA[d8=2.26×10 10 m]]> <![CDATA[d9=1.94×10 -10 m]]> <![CDATA[d10=1.84×10 -10 m]]>

[0182] Cape of Repose

[0183] Using a POWDER TESTER PT-X model (Hosokawa Micron Corporation), the vibration time was set to 30 seconds, the amplitude to 0.5 mm, and the frequency to 50 Hz to measure the angle of repose.

[0184] Particle hardness

[0185] The particle hardness of HAp powder was measured using a New GRANO GM-N type particle hardness measuring device (Okada Seiko Co., Ltd.) under the following conditions.

[0186] Measurement conditions: The measurement speed was set to 10 μm / s, the maximum detection reduction rate was set to 80%, and the sample stage detection load was set to 10.0 gf. Ten measurements were performed, and the average value was calculated.

[0187] Appearance

[0188] The appearance of each HAp powder was observed using a field emission scanning electron microscope at 500x and 10000x magnification.

[0189] Powder X-ray diffraction analysis

[0190] Measurements were performed using an X-ray diffraction apparatus, "SmartLab" (Rigaku Corporation), in the range of 2θ = 25–50° (measurement conditions: target: Cu, tube voltage: 40 kV, tube current: 30 mA, scanning range: 20–50°, scanning speed: 1.000° / min, scanning step: 0.02°, scanning mode: continuous).

[0191] 2-2. Plasma Spraying Test

[0192] After roughening the surface of a Ti-6Al-4V alloy substrate (30 mm long, 40 mm wide, 3 mm thick) by sandblasting, an HAp coating was formed using the HAp powders of Examples 1, 5, and 6 under atmospheric pressure and the plasma sputtering conditions shown in Table 3. Alternatively, after roughening the surface of a PEEK substrate (30 mm long, 40 mm wide, 5 mm thick) by sandblasting, an HAp coating was formed using the HAp powders of Examples 1-4 and Comparative Examples 1-7 under atmospheric pressure and the plasma sputtering conditions shown in Table 3.

[0193] It should be noted that in the plasma spraying conditions shown in Table 3 below, the use of argon and helium as working gases results in lower flame energy. Therefore, even when using Hap for plasma spraying on PEEK substrates, no thermal deformation or thermal decomposition of the substrate occurs.

[0194] Table 3

[0195] Plasma sputtering conditions

[0196]

[0197] The HAp coating was evaluated using the following methods to assess cross-sectional hardness, coating thickness, surface roughness, wear amount, impurity phases (α-TCP (α-tricalcium phosphate), β-TCP (β-tricalcium phosphate), TTCP (tetracalcium phosphate), CaO), color difference, crystallinity, Ca / P ratio, and appearance.

[0198] Cross-sectional hardness

[0199] The cross-sectional hardness of the HAp coating was determined using a Vickers hardness tester at a test force of 0.3 kg.

[0200] Coating thickness

[0201] The thickness of the HAp coating was measured using a micrometer.

[0202] Surface roughness

[0203] The surface roughness (arithmetic mean roughness: Ra) of the HAp coating was determined using a surface roughness meter based on JIS B 0031:1994.

[0204] Wear

[0205] The wear was measured using a SUGA abrasion tester with a load of 1N, SiC#320 abrasive paper, and 100 abrasion cycles.

[0206] impurity phase

[0207] A standard sample was prepared by mixing HAp powder (Example 3) with each impurity phase in a specified amount (0.5 wt%, 1.0 wt%, 2.5 wt%, 5.0 wt%, 6.0 wt%). The diffraction pattern of the standard sample was then measured using a powder X-ray diffraction apparatus "SmartLab" (Rigaku Corporation) in the range of 2θ = 25–50° (measurement conditions: target: Cu, tube voltage: 40 kV, tube current: 30 mA, scan range: 25–50°, scan speed: 1.000° / min, scan step: 0.02°, scan mode: continuous). The diffraction angle (θ) corresponding to the interplanar spacing (d) shown in Table 4 was calculated using the Bragg formula d = λ / 2sinθ, and the integrated intensity of the diffraction peak with this diffraction angle (2θ) as the peak position was calculated. A standard curve was constructed from the ratio of the integrated intensity of each impurity phase relative to the calculated integrated intensity of HAp and the corresponding content of each impurity phase. Then, under the same conditions, the HAp coating (test sample) was measured, and the impurity phases were calculated from the HAp, the integrated intensity of each impurity phase, and the aforementioned standard curve.

[0208] Table 4

[0209]

[0210] Ca / P ratio

[0211] Based on the content of the aforementioned impurity phases, the Ca / P ratio of the HAp coating is calculated using the following formula.

[0212] Mathematical Formula 1

[0213] Ca / P = nCa / nP

[0214] nCa = 10 / M HA ×W HA +3 / M TCP ×(W TCPα +W TCPβ )+1 / M CaO ×W CaO

[0215] nP = 6 / M HA ×W HA +2 / M TCP ×(W TCPα +W TCPβ )

[0216] nCa: Number of Ca moles

[0217] nP: Number of moles of P

[0218] M HA :HAp molar mass

[0219] M TCP TCP Moore Mass

[0220] M CaO CaO molar mass

[0221] W HA HAp content

[0222] W TCPα α-TCP content

[0223] W TCPβ β-TCP content

[0224] W CaO CaO content

[0225] Degree of crystallinity

[0226] For samples (pretreated samples) obtained by treating HAp coating (test sample) and HAp powder (Example 4) at 1000°C for 15 hours, the diffraction pattern was measured using an X-ray diffraction apparatus "SmartLab" (Rigaku Corporation) in the range of 2θ = 25–50° (measurement conditions: target: Cu, tube voltage: 40 kV, tube current: 30 mA, scanning range: 25–50°, scanning speed: 24,000° / min, scanning step: 0.02°, scanning mode: continuous). The diffraction angle (θ) corresponding to the interplanar spacing (d) shown in Table 2 above was calculated using the Bragg formula d = λ / 2sinθ. For the diffraction peak with this diffraction angle (2θ) as the peak position, the ratio of the sum of the integrated intensities of the peaks of the test sample to the sum of the integrated intensities of the peaks of the pretreated sample was calculated.

[0227] Color difference

[0228] For the HAp coating formed on the substrate, a colorimeter (Nippon Denshoku Kogyo Co., Ltd. "ZE6000") is used to determine the L value, a value and b value under reflective conditions, and W (whiteness) is calculated according to the following formula.

[0229] W = 100 - [(100 - L)] 2 +(a 2 +b 2 ) 1 / 2

[0230] Appearance

[0231] The cross-section of the HAp coating was observed using a scanning electron microscope at 500x and 1000x magnification.

[0232] 3. Evaluation Results

[0233] The results are shown in Tables 5 and 6, and Figures 1 to 9. Figure 1-1 , Figure 1-2 and Figure 1-3 Images of the appearance of HAp powder obtained by microscopic observation are shown. Figure 2-1 and Figure 2-2 The image shown is a microscopic image of the cross-sectional appearance of the HAp coating. Figures 3-8 The results of determining the pore size distribution of HAp powder by mercury porosimetry are shown. Figure 9 The results of powder X-ray diffraction analysis of the HAp powder of Example 1 are shown.

[0234] It is believed that in the HAp powders of Comparative Examples 1-4 and Comparative Example 6, due to the large particle size, the energy of the plasma flame was insufficient, and the particles themselves could not melt, thus failing to form a coating. It is believed that in the HAp powder of Comparative Example 7, due to the small particle size, the flowability was low, resulting in unstable supply to the spraying apparatus, and therefore, a coating could not be formed. Furthermore, it is believed that in the HAp powder of Comparative Example 5, although the particle size was appropriate, the large pore volume prevented the heat from the plasma flame from being conducted to the entire particle, leaving unmelted powder residue in the coating, increasing coating wear, and thus reducing the hardness of the coating.

[0235] In contrast, the HAp coatings formed using the HAp powders of Examples 1-6 via plasma sputtering exhibited approximately 1.2 times greater hardness compared to Comparative Example 5, and demonstrated more than 3.0 times greater resistance to wear. It is believed that the HAp powders of Examples 1-6 have an average particle size (D50) as small as 15-40 μm and a pore volume of 0.01-0.30 cc / g with a pore size of 2000 nm or less. Therefore, even with low flame energy, the particles can melt uniformly. As a result, thermal deformation and thermal decomposition do not occur not only in titanium alloy substrates but also in PEEK substrates, enabling the formation of HAp coatings with high hardness and low wear. Furthermore, the HAp coatings formed using the HAp powders of Examples 1-6 maintain high crystallinity and low impurity phases, making them suitable for use as implants.

[0236] Table 5

[0237]

[0238] Table 6

[0239]

Claims

1. A material for plasma sputtering, comprising hydroxyapatite powder, wherein the average particle size (D) of the hydroxyapatite powder is... 50 The pore size is 15~40μm, the pore volume below 2000nm as determined by mercury porosimetry is 0.01~0.30cc / g, the pore volume as determined by gas adsorption is 0.001~0.003cc / g, and the pore volume above 2000nm as determined by mercury porosimetry is 0.20~0.80cc / g.

2. The material for plasma sputtering as described in claim 1, wherein, The pore volume of pores with a diameter of less than 2000 nm, as determined by mercury porosimetry, is 0.01~0.25 cc / g.

3. The material for plasma sputtering as described in claim 1 or 2, wherein, The average particle size (D) 50 The thickness is 20~40μm.

4. The material for plasma sputtering as described in claim 1 or 2, wherein, The BET specific surface area of ​​the hydroxyapatite powder is less than 5 m². 2 / g.

5. The material for plasma sputtering as described in claim 3, wherein, The BET specific surface area of ​​the hydroxyapatite powder is less than 5 m². 2 / g.

6. The material for plasma sputtering as described in claim 1 or 2, wherein, The pore volume of the hydroxyapatite powder above 2000 nm, as determined by mercury porosimetry, is 0.30~0.75 cc / g.

7. The plasma sputtering material as described in claim 1 or 2, used for plasma sputtering in which a gas composed of only one or more monatomic molecules is used as the working gas.

8. The plasma sputtering material as described in claim 1 or 2, used to form a coating on a substrate.

9. The material for plasma sputtering as described in claim 8, wherein, The substrate is made of resin, metal, or ceramic.

10. The material for plasma sputtering as described in claim 8, wherein, The material of the substrate is polyetheretherketone.

11. The material for plasma sputtering as described in claim 8, wherein, The substrate is made of titanium alloy.

12. The material for plasma sputtering as described in claim 8, wherein, The substrate is an implant.

13. The material for plasma sputtering as described in claim 9, wherein, The substrate is an implant.

14. A method for forming a hydroxyapatite coating, wherein, Plasma sputtering is performed on the material for plasma sputtering as described in claim 1 or 2 to form a hydroxyapatite coating on the substrate.

15. The method for forming a hydroxyapatite coating as described in claim 14, wherein, The substrate is made of resin, metal, or ceramic.

16. The method for forming a hydroxyapatite coating as described in claim 14, wherein, The material of the substrate is polyetheretherketone.

17. The method for forming a hydroxyapatite coating as described in claim 14, wherein, The substrate is made of titanium alloy.

18. The method for forming a hydroxyapatite coating as described in claim 14, wherein, The substrate is an implant.

19. Applications of hydroxyapatite powder as a material for plasma sputtering, among which, The average particle size (D) of the hydroxyapatite powder 50 The pore size is 15~40μm, the pore volume below 2000nm as determined by mercury porosimetry is 0.01~0.30cc / g, the pore volume as determined by gas adsorption is 0.001~0.003cc / g, and the pore volume above 2000nm as determined by mercury porosimetry is 0.20~0.80cc / g.

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