CN105624753B - A kind of medical porous titanium or titanium alloy uniform deposition hydroxyapatite coating layer technique - Google Patents

Abstract

The invention relates to the field of surface modification treatment of medical materials, and specifically discloses a process for uniformly depositing a hydroxyapatite coating on medical porous titanium and titanium alloys. The process of depositing hydroxyapatite coating on porous titanium and titanium alloy of the present invention includes pretreatment of porous metal substrate, preparation of electroplating solution and electrodeposition process. The pretreatment process of the present invention can effectively mechanically polish and clean the inner and outer surfaces of the porous metal; the electrodeposition process uses a rotating electrode electrolysis device to perform electrodeposition treatment of hydroxyapatite on the porous metal, which can effectively reduce the internal and external surface of the porous metal. The thickness of the surface diffusion layer can effectively avoid the problem of asynchronous electrodeposition process on the inner and outer surfaces of the porous structure under the condition of diffusion and mixing control; by adjusting the rotational speed, a uniform hydroxyapatite electrodeposition layer on the inner and outer surfaces of the porous metal can be obtained.

Description

A uniform deposition process of hydroxyapatite coating on medical porous titanium and titanium alloy

technical field

The invention relates to the field of surface modification treatment of medical materials, in particular to a process for uniformly depositing hydroxyapatite coatings on medical porous titanium and titanium alloys.

Background technique

It is a current trend that porous metals are used in orthopedic clinics such as the treatment of osteonecrosis and bone defects. The results of clinical trials show that even implant materials with only porous surfaces can significantly improve the histocompatibility of materials, which is mainly manifested in the greatly improved bonding ability and bonding strength of porous materials with bone tissue and fibrous tissue . From the perspective of biomechanics, the advantages of porous titanium or titanium alloy bone implants are very obvious: by adjusting the thickness of the scaffold, porous titanium alloys with different porosity, pore diameter and distribution can be produced to meet the support requirements of the bearing bone. From the perspective of material biocompatibility, although metal titanium and its alloys are the most widely used metals in clinical orthopedic implant materials, they are still biologically inert compared with autologous bone and bioactive artificial bone, and cannot produce bone with bone tissue. sexual union. Since the osteogenic activity of the material after implantation is mainly determined by its surface properties, the clinically used titanium and titanium alloy implant materials need further surface treatment.

Hydroxyapatite [Ca ₁₀ (PO ₄ ) ₆ (OH) ₂ ] (Hydroxyapatite, HA) has a similar chemical composition and crystal structure to apatite, the main mineral in human hard tissues, and has excellent biocompatibility. At present, titanium-based HA-coated composites have been widely used in clinical practice. There are many techniques for preparing HA coatings on the surface of dense titanium metal, mainly including plasma spraying, laser cladding, ion beam assisted deposition, sol-gel, bionic deposition, electrodeposition and other methods. However, conventional beamline surface treatment cannot treat the internal surface of porous metal due to the inherent directivity limitation. The special microporous structure of porous metal determines that the difficulty of surface modification lies in the treatment of the pores distributed inside the porous alloy and the inner walls of the micropores. Therefore, the surface modification of porous titanium and its alloys mainly uses chemical and electrochemical methods, both of which are carried out in a solution, and the solution can easily enter the interior of the porous metal.

However, the existing porous metal electrochemical deposition process only uses porous metal as a flat metal with enlarged surface area, and does not optimize and adjust the original dense metal electrodeposition process according to the structural characteristics of porous metal. In the actual electrochemical deposition process, due to electrochemical polarization, concentration polarization, and ohmic polarization, the effective overpotential at different electrode thicknesses distributed inside the porous structure is significantly lower than that on the outermost surface, resulting in a gap in the porous structure. The growth process of the electrodeposited layer at different positions of the auxiliary electrode and the final surface quality are not uniform, which is unavoidable for any porous metal electrochemical reaction process. If this non-uniform chemical and electrochemical reaction mechanism is not intervened, it will have Surface modification of a certain thickness of porous metal will inevitably lead to inhomogeneity.

Contents of the invention

In view of this, it is necessary to provide a process for uniformly depositing hydroxyapatite coatings on medical porous titanium and titanium alloys to address the above problems.

To achieve the above object, the present invention takes the following technical solutions:

The uniform deposition process of hydroxyapatite coating on medical porous titanium and titanium alloy of the present invention comprises:

Step 1: Pretreatment of Porous Metal Substrates

(1) Mechanical polishing: Use the automatic mode of the drum sandblasting machine to mechanically polish the inner and outer surfaces of the porous metal sample to remove irregular burrs during the forming process of the inner and outer surfaces of the porous metal;

(2) Degreasing: After the mechanically polished porous metal sample is placed in a hot alkali degreasing solution for degreasing treatment under supergene conditions, the sample is taken out and rinsed with deionized water;

(3) Acid erosion: finally utilize pickling solution to carry out pickling treatment under ultrasonic wave, clean with deionized water after treatment; Naturally dry, for subsequent use;

Step 2: Preparation of electroplating solution

Prepare a solution with a concentration 2-3 times lower than that of conventional electroplating solutions containing calcium salts, phosphates and supporting electrolytes;

Step 3: Electrodeposition Process

With the porous metal sample pretreated in step 1 as the cathode and the platinum-plated titanium plate as the anode, the electroplating solution prepared in step 2 is heated to 60-80°C, and the electrolytic solution is heated to 60-80°C using a rotating electrode electrolysis device under constant current or constant current. Conduct electrodeposition on the inner and outer surfaces of the metal sample in the potential mode; take out the electrodeposited sample, rinse it with deionized water, and dry it in a vacuum oven to obtain a uniform hydroxyapatite coating on the inner and outer surfaces. Layer porous metal sample;

The porous metal is porous titanium or titanium alloy.

Further, in the mechanical polishing process described in step 1: the compressed air pressure is 4-10 MPa when the sandblasting machine is working; brown corundum or white corundum with a particle size of 100 to 280 is selected as the sandblasting abrasive for sandblasting when the sandblasting machine is working 1 -5min.

Further, when the porous metal sample is treated with hot alkali degreasing in step 1, the hot alkali temperature is 70-90° C., and the treatment time is 2-10 minutes.

The hot alkali degreasing liquid is 20~40g·L ^-1 NaH ₂ PO ₂ ·H ₂ O, 10~20g·L ^-1 anhydrous Na ₂ CO ₃ , 3~5g·L ^-1 NaOH dissolved in Made in deionized water.

Further, the pickling solution in step 1 is a mixed solution prepared with HF and HNO ₃ , and the mixed solution includes 5-15 mL·L ^-1 HF and 10-30 mL·L ^-1 HNO ₃ .

Further, the pH value of the electroplating solution at room temperature in step 2 is 4.5-6.0; the pH value of the electroplating solution is 0.1-10mL·L ^-1 HCl solution, 0.1-10mL·L ^-1 HNO ₃ solution or 0.1-10mL·L-1 HNO 3 solution. 10mL·L ^-1 ammonia water for adjustment.

Further, the Ca ²⁺ in the calcium salt in step 2 is derived from at least one of CaCl ₂ , CaCl ₂ , Ca(NO ₃ ) ₂ , Ca(NO ₃ ) ₂ ·4H ₂ O; the phosphorus salt H ₂ PO ₄ ^- , HPO ₄ ^2- in NH ₄ H ₂ PO ₄ , NaH ₂ PO ₄ , KH ₂ PO ₄ , (NH ₄ ) ₂ HPO ₄ , Na ₂ HPO ₄ , K2HPO ₄ at least one species; the supporting electrolyte is at least one of sodium chloride, potassium chloride, sodium nitrate, potassium nitrate, sodium sulfate, and potassium sulfate.

Further, during the electrodeposition process in step 3, the electrode rotation speed of the rotating electrode electrolysis device is 10-1000rpm, the current density is 1.0-50.0mA·cm ^-2 , the deposition potential is 1.0-10.0V, and the electrodeposition time is 0.5~4h; the drying temperature in the vacuum drying oven is 80~100℃, and the drying time is 1~4h.

A rotating electrode electrolysis device, comprising a constant temperature water bath, an electrolytic cell, a platinum-plated titanium plate as an anode, a porous metal as a cathode, and a rotating electrode rod; the electrolytic cell is placed in a constant temperature water bath; the platinum-plated titanium plate Placed in the electrolytic cell; one end of the rotating electrode rod is connected to the porous metal placed in the electrolytic cell, and the other end is connected to a DC power supply or a potentiostat; the end of the rotating electrode rod connected to the porous metal sample is designed with an external thread, The rotational speed of the rotating electrode rod is controlled by a motor speed controller.

Further, the platinum-coated titanium plate is square or circular; the number of the square platinum-coated titanium plate is one pair or more.

The beneficial effects of the present invention are:

(1) Dilute concentration electroplating solution: the present invention adopts conventional electroplating solutions such as calcium salts and phosphorus salts of dilute concentration, and the concentration is 2-3 times lower than that of conventional electroplating solutions to ensure that the porous metal electrodeposition reaction is mixed by diffusion or diffusion electrochemical control process.

(2) The pretreatment of the porous metal sample of the present invention adopts the drum sandblasting device under the automatic mode, and the ultrafine brown corundum or white corundum abrasive is operated under the action of high-pressure air flow, which can effectively mechanically clean the inner and outer surfaces of the porous metal. Grinding treatment; chemical degreasing and pickling under ultrasonic conditions can further effectively pretreat the inner and outer surfaces of porous metals.

(3) The present invention adopts the rotating electrode electrolysis device to carry out the electrodeposition treatment of hydroxyapatite to the porous metal, which is different from the traditional air stirring, magnetic stirring, etc., which rely on the flow of the solution to improve the mass transfer capacity of the electrochemical reaction, and the rotating electrode method relies on the work The electrode rotates at high speed, so that the solution flow near the porous metal electrode meets the "laminar flow" condition, which can effectively reduce the thickness of the diffusion layer on the inner and outer surfaces of the porous metal, and effectively avoid the asynchronous electrodeposition process on the inner and outer surfaces of the porous structure under the condition of diffusion mixing control The problem; by adjusting the rotational speed to obtain a uniform hydroxyapatite electrodeposition layer on the inner and outer surfaces of the porous metal.

Description of drawings

Fig. 1 is a structural schematic diagram of the rotating electrode electrolysis device of the present invention.

FIG. 2 is a top view of FIG. 1 .

Fig. 3 is a top view of Fig. 1 with a pair of platinized titanium plate electrodes added.

FIG. 4 is a top view of a circular platinum-coated titanium plate replacing the square platinum-coated titanium plate in FIG. 1 .

Fig. 5 is a schematic diagram of comparing the potential distribution between the rotating electrode electrolysis device of the present invention and conventional magnetic stirring.

Reference signs: constant temperature water bath 1; electrolytic tank 2; platinized titanium plate 3; porous metal 4; rotating electrode rod 5.

Detailed ways

In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be further clearly and completely described below in conjunction with the embodiments of the present invention. It should be noted that the described embodiments are only some of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Example

The uniform deposition process of hydroxyapatite coating on medical porous titanium and titanium alloy of the present invention comprises:

Step 1: Pretreatment of Porous Metal Substrates

(1) Mechanical polishing: Use the automatic mode of the drum sandblasting machine to mechanically polish the inner and outer surfaces of porous titanium or titanium alloy samples. Brown corundum or white corundum with a particle size of 100-280 is used as sandblasting abrasive, and sandblasting is performed for 1-5 minutes to remove irregular burrs during the forming process of the inner and outer surfaces of the porous structure;

(2) Degreasing: Then place the mechanically polished porous titanium or titanium alloy sample in a hot alkali degreasing solution at 70-90°C for 2 to 10 minutes under supergene conditions, then take out the sample and rinse it with deionized water clean. The hot alkali degreasing liquid is 20~40g·L ^-1 NaH ₂ PO ₂ ·H ₂ O, 10~20g·L ^-1 anhydrous Na ₂ CO ₃ , 3~5g·L ^-1 NaOH dissolved in Made in deionized water.

(3) Acid erosion: finally utilize pickling solution to carry out pickling treatment under ultrasonic conditions, clean up with deionized water after treatment; Naturally dry, standby; Described pickling solution is with HF and _HNO Prepared A mixed solution comprising 5-15 mL·L ^-1 HF and 10-30 mL·L ^-1 HNO ₃ . Preferably, the mass percent concentration of HF used to prepare the mixed solution is 48%, and the mass percent concentration of HNO ₃ is 68%.

Step 2: Preparation of electroplating solution

Prepare a solution with a concentration 2-3 times lower than conventional electroplating solutions containing calcium salts, phosphates and supporting electrolytes; the pH value of the electroplating solution at room temperature is 4.5-6.0; the pH value of the electroplating solution is 0.1-10mL·L ^-1 HCl solution, 0.1~10mL·L ^-1 HNO ₃ solution or 0.1~10mL·L ^-1 ammonia water.

Step 3: Electrodeposition Process

The porous titanium or titanium alloy sample pretreated in step 1 is used as the cathode, and the platinum-plated titanium plate is used as the anode. Electrodeposition is performed on the inner and outer surfaces of porous titanium or titanium alloy samples by current or constant potential; during the electrodeposition process, the electrode rotation speed of the electrolysis device is 10-1000rpm, the current density is 1.0-50.0mA·cm ^-2 , and the deposition potential is 1.0- 10.0V, the deposition time is 0.5-4h; the sample after electrodeposition is taken out, rinsed with deionized water, and dried in a vacuum oven at 80-100°C for 1-4h, that is, on the porous titanium or titanium alloy sample A hydroxyapatite coating is formed on the inner and outer surfaces.

As a preference, Ca ²⁺ in the calcium salt described in step 2 is derived from at least one of CaCl ₂ , CaCl ₂ , Ca(NO ₃ ) ₂ , Ca(NO ₃ ) ₂ ·4H ₂ O; the phosphorus salt H ₂ PO ₄ ^- , HPO ₄ ^2- in NH ₄ H ₂ PO ₄ , NaH ₂ PO ₄ , KH ₂ PO ₄ , (NH4) ₂ HPO ₄ , Na ₂ HPO ₄ , K ₂ HPO ₄ at least One; the supporting electrolyte is at least one of sodium chloride, potassium chloride, sodium nitrate, potassium nitrate, sodium sulfate, and potassium sulfate.

Preferably, the porous pure titanium in the present invention is TA1, TA2, TA3, TA4; the porous titanium alloy is Ti-6Al-4V.

The conventional electroplating solution containing calcium salt, phosphate and supporting electrolyte in the present invention refers to: the concentration of Ca ²⁺ is 10.1～50.0mmol·L-1, and the concentration of H ₂ PO ^4- is 5.1～30.0mmol·L- 1. An electroplating solution with a Ca/P molar ratio of 1.6-1.8 and a supporting electrolyte concentration of 0.5-2.0 mol·L ^-1 ; for example, the conventional electroplating solution A is prepared as: Ca(NO ₃ ) ₂ and (NH ₄ ) ₂ HPO ₄ Concentrations are 14.01mmol/L and 8.33mmol/L respectively, Ca/P molar ratio is 1.67, supporting electrolyte sodium nitrate is 1.2mol/L, pH value is 5.5; conventional plating solution B is prepared as: CaCl ₂ and NH ₄ H ₂ P0 ₄ concentrations They are 21.01mmol/L and 12.50mmol/L respectively, the Ca/P molar ratio is 1.67, the supporting electrolyte sodium chloride is 0.8mol/L, and the pH value is 5.0. The diluted electroplating solution used in the present invention is 2-3 times lower than conventional electroplating solution A or B as the electroplating solution to ensure that the electrodeposition reaction of porous titanium or titanium alloy is a diffusion or diffusion electrochemical mixing control process.

As shown in Figure 1, be the rotating electrode electrolysis device of the present invention, comprise constant temperature water bath 1, electrolyzer 2, the platinized titanium plate 3 as anode, the porous titanium or titanium alloy 4 as cathode, rotating electrode rod 5; Described The electrolytic cell 2 is placed in the constant temperature water bath 1; the platinum-plated titanium plate 3 is placed in the electrolytic cell 2; one end of the rotating electrode rod 5 is connected with the porous titanium or titanium alloy 4 placed in the electrolytic cell 2, and the other One end is connected to a DC power supply or a potentiostat; the rotating electrode rod 5 is connected to a porous titanium or titanium alloy sample 4, and the other end is designed with an external thread, and the rotating speed of the rotating electrode rod 5 is controlled by a motor speed controller.

As shown in Figure 2-4, it is the top view of the rotating electrode electrolysis device of the present invention, as preferably, the rotating electrode electrolysis device can select different numbers of anode platinum-plated titanium plates according to the size of the porous titanium or titanium alloy sample and shape; when the size of the sample becomes larger, four rectangular counter electrode platinized titanium plates or circular platinized titanium plates can be selected.

As shown in Figure 5, it is a 10mm thick porous titanium sample of the present invention, under conventional magnetic stirring and when the rotating electrode electrolysis device of the present invention rotates at high speed, the potential distribution inside the electrode under the same electrodeposition process conditions:

In Fig. 5 (a) is a potential distribution diagram of magnetic stirring under a constant current of 10 ^-3 A·cm ² , and (b) a potential distribution diagram of using the electrode of the present invention to move at a speed of 500 rpm relative to the solution.

It can be seen from the figure that under the conditions of conventional magnetic stirring and constant current of 10 ^-3 A cm ² , the potential difference between the surface and the bottom of the 10mm thick porous titanium sample can reach 500mV, but the potential difference is only insufficient when the electrode of the present invention moves at high speed relative to the solution. 100mV. As the size of the porous titanium sample increases, the difference in effective overpotential at different thicknesses also increases. According to the above experimental results, it can be concluded that it is feasible to improve the uniformity of electrodeposition on the inner and outer surfaces of porous titanium by reducing the uneven potential distribution by effectively moving the electrode at a high speed relative to the solution.

The above-mentioned embodiments only express several implementation modes of the present invention, and the description thereof is relatively specific and detailed, but should not be construed as limiting the patent scope of the present invention. It should be pointed out that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent for the present invention should be based on the appended claims.

Claims (9)

1. A process for evenly depositing a hydroxyapatite coating on medical porous titanium and titanium alloys, characterized in that it comprises: Step 1: Pretreatment of Porous Metal Substrates (1) Mechanical polishing: Use the automatic mode of the drum sandblasting machine to mechanically polish the inner and outer surfaces of the porous metal sample to remove irregular burrs during the forming process of the inner and outer surfaces of the porous metal; (2) Degreasing: The mechanically polished porous metal sample is then placed in a hot alkali degreasing solution for super After degreasing treatment under acoustic conditions, take out the sample and rinse it with deionized water; (3) Acid etching: Finally, use the acid immersion solution to carry out pickling treatment under ultrasonic waves, and use it after treatment. Clean with deionized water; dry naturally and set aside; Step 2: Preparation of electroplating solution Prepare a solution with a concentration 2-3 times lower than that of conventional electroplating solutions containing calcium salts, phosphates and supporting electrolytes; Step 3: Electrodeposition process With the porous metal sample pretreated in step 1 as the cathode and the platinum-plated titanium plate as the anode, heat the electroplating solution prepared in step 2 to 60~80ºC, and use a rotating electrode electrolysis device under constant current or constant potential Electrodeposition is performed on the inner and outer surfaces of the metal sample in this way; the sample after electrodeposition is taken out, rinsed with deionized water, and dried in a vacuum oven to obtain a uniform hydroxyapatite coating on the inner and outer surfaces The porous metal sample; The porous metal is porous titanium or titanium alloy; During the electrodeposition process in step 3, the electrode rotation speed of the rotating electrode electrolysis device is 10~1000rpm, the current density is 1.0~50.0mA·cm ^-2 , the deposition potential is 1.0~10.0V, and the electrodeposition time is 0.5~4h ;The drying temperature in the vacuum drying oven is 80~100ºC, and the drying time is 1~4h. 2. The uniform deposition process of hydroxyapatite coating on medical porous titanium and titanium alloy according to claim 1, characterized in that, in the mechanical polishing process described in step 1: the compressed air pressure is 4-10MPa when the sandblasting machine is working ; When grinding, choose brown corundum or white corundum with a particle size of 100~280 as the sandblasting abrasive, and perform sandblasting for 1-5min. 3. The process for evenly depositing hydroxyapatite coatings on medical porous titanium and titanium alloys according to claim 1, characterized in that, when the hot alkali degreasing process porous metal samples described in step 1, the hot alkali temperature is 70- 90ºC, the processing time is 2~10min. 4. The process for evenly depositing hydroxyapatite coatings on medical porous titanium and titanium alloys according to claim 3, characterized in that the hot alkali degreasing solution is 20~40g·L ^-1 NaH ₂ PO ₂ · H ₂ O, 10~20g·L ^-1 anhydrous Na ₂ CO ₃ , 3~5g·L ^{- 1} NaOH dissolved in deionized water. 5. The process for evenly depositing hydroxyapatite coatings on medical porous titanium and titanium alloys according to claim 1, wherein the pickling solution in step 1 is a mixed solution prepared with HF and HNO ₃ , and the The above mixed solution includes 5~15mL·L ^-1 HF and 10~30mL·L ^-1 HNO ₃ . 6. The process of evenly depositing hydroxyapatite coating on medical porous titanium and titanium alloy according to claim 1, characterized in that, the pH value of the electroplating solution at room temperature in step 2 is 4.5～6.0; The pH value was adjusted with 0.1~10mL·L ^-1 HCl solution, 0.1~10mL·L ^-1 HNO ₃ solution or 0.1~10mL·L ^-1 ammonia water. 7. The process for evenly depositing hydroxyapatite coatings on medical porous titanium and titanium alloys according to claim 1, wherein the ^Ca in the calcium salt in step 2 is derived from CaCl ₂ , CaCl ₂ , Ca( At least one of NO ₃ ) ₂ , Ca(NO ₃ ) ₂ ·4H ₂ O; the H ₂ PO ₄ ^- and HPO ₄ ^2- in the phosphate are derived from NH ₄ H ₂ PO ₄ , NaH ₂ PO _4. At least one of KH ₂ PO ₄ , (NH ₄ ) ₂ HPO ₄ , Na ₂ HPO ₄ , K ₂ HPO ₄ ; the supporting electrolyte is sodium chloride, potassium chloride, sodium nitrate, potassium nitrate, At least one of sodium sulfate and potassium sulfate. 8. The uniform deposition process of hydroxyapatite coating on medical porous titanium and titanium alloy according to any one of claims 1-7, characterized in that, the rotating electrode electrolysis device includes a constant temperature water bath and an electrolytic cell as an anode The platinum-plated titanium plate is used as the porous metal of the cathode, and the electrode rod is rotated; the electrolytic cell is placed in a constant temperature water bath; the platinum-plated titanium plate is placed in the electrolytic cell; one end of the rotating electrode rod is placed in the electrolytic cell The porous metal in the sample is connected, and the other end is connected to a DC power supply or a potentiostat; the end of the rotating electrode rod connected to the porous metal sample is designed with an external thread, and the rotation speed of the rotating electrode rod is controlled by a motor speed controller. 9. The process for evenly depositing hydroxyapatite coatings on medical porous titanium and titanium alloys according to claim 1, wherein the platinum-coated titanium plate is square or ring-shaped; the number of square platinum-coated titanium plates is one right or above.