A medical bio-gradient hard coating and its preparation method

Abstract

The present invention discloses a medical bio-gradient hard coating and its preparation method, belonging to the field of medical technology. The coating comprises a Cr coating, a CrN coating, a TiCrN coating, a TiN coating, and a TiNbN coating stacked in sequence. The present invention prepares a chemically gradient hard coating on a cobalt alloy surface, enhancing the bonding strength between the film layer and the substrate.

Description

Technical Field

[0001] The present invention relates to the field of medical technology, in particular to a medical biological gradient hard coating and a preparation method thereof. Background Art

[0002] The prior art discloses a method for improving the service life and biocompatibility of implants. The method uses physical vapor deposition technology to prepare a TiNbN coating on the outer surface of the bone plate body and the bone screw body. The coating thickness is 3-5 μm, the bonding strength between the coating and the substrate is HF 1-2 quality, and the hardness is HV>2000.

[0003] However, a single layer of TiNbN coating is deposited on the surface of the implant, and the single layer has a certain internal stress. During use, if the film layer cracks, the crack will quickly expand and cause the film layer to fail. Before preparing the hard material coating, a TiNb bonding layer was prepared on the substrate, but from the bonding strength results, the bonding strength between the coating and the substrate was not significantly enhanced. Summary of the Invention

[0004] In response to the problems in the above-mentioned background technology, the present invention proposes a medical bio-gradient hard coating and its preparation method. The hard coating with a gradient chemical composition is prepared on the surface of a cobalt alloy, thereby enhancing the bonding strength between the film layer and the substrate.

[0005] The technical solution of the present invention is achieved in this way:

[0006] A medical biological gradient hard coating comprises a Cr coating, a CrN coating, a TiCrN coating, a TiN coating and a TiNbN coating stacked in sequence.

[0007] A method for preparing a medical bio-gradient hard coating is used to prepare the above-mentioned medical bio-gradient hard coating by magnetron sputtering technology, and specifically comprises the following steps:

[0008] Step 1: Place the Cr metal target, TiCr alloy target, Ti metal target, and TiNb alloy target into the corresponding chambers of the magnetron sputtering deposition chamber, keep the chamber doors open, and place the sample to be coated on the sample holder of the magnetron sputtering deposition chamber;

[0009] Step 2: continuously evacuate the magnetron sputtering deposition chamber. When the vacuum reaches 2×10-3 Pa, turn on the heating device to raise the temperature of the deposition chamber to 400° C.

[0010] Step 3: Continue to evacuate. When the vacuum reaches 1×10-4Pa, set the temperature to 300°C and introduce 100 sccm of argon. When the temperature drops to 300°C, close the argon valve and continue evacuating for 20 minutes.

[0011] In step 4, 100 sccm of argon gas was introduced into the deposition chamber for 30 minutes.

[0012] Step 5: Close the argon valve and continue to evacuate for 30 minutes.

[0013] Step 6, repeat steps 4 to 5 twice;

[0014] Step 7: The argon flow rate was set to 80 sccm, the substrate bias power supply was turned on, the substrate voltage was set to 150 V, and the sample surface was cleaned for 20 min. Subsequently, the substrate voltage was adjusted to 200 V and the cleaning was continued for 30 min.

[0015] Step 8: 30 sccm of argon gas was introduced, the chambers of the TiCr alloy target, the Ti metal target, and the TiNb alloy target were closed, and a Cr film layer was deposited on the substrate surface under the conditions of a voltage of 50-150 V, a pressure of 1-2 Pa, and a target power of 150 W.

[0016] Step 9: 30 sccm of argon and 60 sccm of nitrogen are introduced into the magnetron sputtering deposition chamber, and a CrN film is deposited under the conditions of a voltage of 50-150 V, a pressure of 1-2 Pa, and a target power of 150 W;

[0017] Step 10: Close the chamber door of the Cr metal target, open the chamber door of the TiCr alloy target, and deposit a TiCrN film under the conditions of a voltage of 50-150 V, a pressure of 1-2 Pa, and a target power of 150 W.

[0018] Step 11: Close the chamber door of the TiCr alloy target, open the chamber door of the Ti alloy target, and deposit a TiN film under the conditions of a voltage of 50-150 V, a pressure of 1-2 Pa, and a target power of 150 W;

[0019] Step 12: Close the chamber door of the Ti metal target, open the chamber door of the TiNb alloy target, and deposit a TiNbN film under the conditions of a voltage of 50-150 V, a pressure of 1-2 Pa, and a target power of 150 W.

[0020] Step 13: Close the nitrogen valve, lower the temperature to below 80°C, close the argon valve, turn off the vacuum system, wait for cooling to room temperature, and take out the sample to complete the coating.

[0021] Furthermore, the thickness of the Cr film layer obtained in step 8 is 0.5 μm, and the deposition temperature is between 300 and 400° C.

[0022] Furthermore, the thickness of the CrN film layer obtained in step 9 is 1 μm, and the deposition temperature is between 300° C. and 400° C.

[0023] Furthermore, the thickness of the TiCrN film obtained in step 10 is 1 μm, and the deposition temperature is between 300° C. and 400° C.

[0024] Furthermore, the thickness of the TiN film obtained in step 11 is 1 μm, and the deposition temperature is between 300° C. and 400° C.

[0025] Furthermore, the thickness of the TiNbN film layer obtained in step 12 is 1.5 μm, and the deposition temperature is between 300° C. and 400° C.

[0026] Furthermore, in step 1, the ratio of alloy elements in the TiCr alloy target is Ti:Cr=80:20 (at%).

[0027] Furthermore, in step 1, the ratio of alloy elements in the TiNb alloy target is Ti:Nb=70:30 (at%).

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. The design of the Cr / CrN / TiCrN / TiN / TiNbN gradient structure reduces the interface mismatch problem caused by chemical element differences, improves the correlation between layers, and thus enhances the bonding strength between the coating and the substrate;

[0030] 2. Gradient hard coating has more interfaces, which can hinder the expansion of cracks and increase the service life of the film layer; DETAILED DESCRIPTION

[0031] The present invention is described in detail below with reference to specific embodiments.

[0032] This invention uses magnetron sputtering technology to produce a biomedical gradient hard coating on a cobalt alloy surface. The gradient hard coating system consists of five layers: a first Cr coating, deposited on the cobalt alloy surface; a second CrN coating; a third TiCrN coating; a fourth TiN coating; and a fifth TiNbN coating, forming a CoCrMo / Cr / CrN / TiCrN / TiN / TiNbN gradient hard coating system. The total coating thickness is approximately 5 μm.

[0033] Compared to single-layer coatings, gradient coatings have smoother transitions between film layers. The presence of film interfaces hinders the expansion of film cracks, imparting a certain toughness to the coating and improving its stability. In the present invention, the gradient variation of the coating's chemical elements improves the matching degree of each interface, thereby improving the interfacial bonding strength and increasing the service life of the implanted prosthesis. The coating deposition technology of the present invention can be used for implants such as knee prostheses, hip prostheses, shoulder prostheses, toe joints, finger joints, wrist joints, and ankle prostheses, including but not limited to articular surfaces.

[0034] The specific implementation steps are as follows:

[0035] (1) Before coating deposition, Ti and Cr metal targets and TiCr and TiNb alloy targets were placed in the magnetron sputtering equipment. Before film deposition, each target was shielded by a baffle. The sample was placed on the sample holder.

[0036] (2) The deposition chamber is vacuumed to 2×10-3Pa, and then the heating device is turned on to raise the temperature of the deposition chamber to 400℃.

[0037] (3) When the vacuum degree reaches 1×10-4Pa, set the temperature to 300℃ and introduce 100sccm of argon. When the temperature drops to 300℃, close the vent valve and evacuate for 20 minutes.

[0038] (4) Introduce argon gas at 100 sccm for 30 minutes.

[0039] (5) Close the argon valve and evacuate for 30 minutes.

[0040] (6) Repeat steps (4)-(5) twice and adjust the parameters to prepare the coating.

[0041] (7) The argon flow rate was set to 80 sccm, the substrate bias power supply was turned on, the substrate voltage was set to 150 V, and the sample surface was cleaned for 20 min. Then, the substrate voltage was adjusted to 200 V and the cleaning time was 30 min.

[0042] (8) 30 sccm of argon was introduced, the Cr metal target baffle was opened, and a Cr film was deposited on the substrate surface under the conditions of a voltage of 50-150 V, a pressure of 1-2 Pa, and a target power of 150 W. The obtained film thickness was 0.5 μm. The deposition temperature was 300-400 °C.

[0043] (9) 30 sccm of argon and 60 sccm of nitrogen were introduced, the Cr metal target baffle was opened, and a CrN film was deposited at a voltage of 50-150 V, a pressure of 1-2 Pa, and a target power of 150 W. The obtained film thickness was 1 μm. The deposition temperature was 300-400 °C.

[0044] (10) Argon (30 sccm) and nitrogen (60 sccm) were introduced, and the TiCr alloy target baffle was opened. A TiCrN film was deposited at a voltage of 50–150 V, a pressure of 1–2 Pa, and a target power of 150 W. The resulting film thickness was 1 μm. The deposition temperature was 300–400°C. The alloying element ratio in the TiCr alloy target was Ti:Cr = 80:20 (at%).

[0045] (11) Argon gas (30 sccm) and nitrogen gas (60 sccm) were introduced, the Ti metal target baffle was opened, and a TiN film was deposited at a voltage of 50–150 V, a pressure of 1–2 Pa, and a target power of 150 W. The resulting film thickness was 1 μm. The deposition temperature was 300–400 °C.

[0046] (12) Argon (30 sccm) and nitrogen (60 sccm) were introduced, and the TiNb alloy target shield was opened. A TiNbN film with a thickness of 1.5 μm was deposited at a voltage of 50–150 V, a pressure of 1–2 Pa, and a target power of 150 W. The deposition temperature was 300–400°C. The alloying element ratio in the TiNb alloy target was 70:30 (at%) Ti:Cr.

[0047] (13) After completing the above steps, a Cr / CrN / TiCrN / TiN / TiNbN gradient coating was obtained.

[0048] Example 1: Comparative coating TiNbN, with a coating thickness of approximately 4.8 μm. The prepared comparative coating is a single layer of TiNbN deposited directly on the cobalt alloy surface. The process steps are (1) to (6) and (13) above.

[0049] Example 2: Gradient hard coating Cr / CrN / TiCrN / TiN / TiNbN, with a coating thickness of about 4.9 μm. (1)-(13),

[0050] Refer to Table 1 for the test standards and hardness test results of Examples 1 and 2.

[0051] Table 1

[0052]

[0053] Refer to Table 2, which shows the test standards and friction and wear test results of Examples 1 and 2.

[0054] Table 2

[0055]

[0056] Refer to Table 3, which shows the test standards and bonding strength test results of Examples 1 and 2.

[0057] Table 3

[0058]

Claims

1. A method for preparing a medical bio-gradient hard coating, for preparing a medical bio-gradient hard coating, wherein the medical bio-gradient hard coating comprises a Cr coating, a CrN coating, a TiCrN coating, a TiN coating and a TiNbN coating stacked in sequence, characterized in that: This is achieved through magnetron sputtering technology, which specifically includes the following steps: Step 1: Place the Cr metal target, TiCr alloy target, Ti metal target, and TiNb alloy target into the corresponding chambers of the magnetron sputtering deposition chamber, keep the chamber doors open, and place the sample to be coated on the sample holder of the magnetron sputtering deposition chamber; Step 2: continuously evacuate the magnetron sputtering deposition chamber. When the vacuum reaches 2×10-3 Pa, turn on the heating device to raise the temperature of the deposition chamber to 400° C. Step 3: Continue to evacuate. When the vacuum reaches 1×10-4Pa, set the temperature to 300°C and introduce 100 sccm of argon. When the temperature drops to 300°C, close the argon valve and continue evacuating for 20 minutes. Step 4: 100 sccm of argon was introduced into the deposition chamber for 30 minutes; Step 5: Close the argon valve and continue to evacuate for 30 minutes. Step 6: Repeat steps 4 to 5 twice; Step 7: The argon flow rate was set to 80 sccm, the substrate bias power supply was turned on, the substrate voltage was set to 150 V, and the sample surface was cleaned for 20 min. Subsequently, the substrate voltage was adjusted to 200 V and the cleaning was continued for 30 min. Step 8: 30 sccm of argon gas was introduced, the chambers of the TiCr alloy target, the Ti metal target, and the TiNb alloy target were closed, and a Cr film layer was deposited on the substrate surface under the conditions of a voltage of 50-150 V, a pressure of 1-2 Pa, and a target power of 150 W. Step 9: 30 sccm of argon and 60 sccm of nitrogen are introduced into the magnetron sputtering deposition chamber, and a CrN film is deposited under the conditions of a voltage of 50-150 V, a pressure of 1-2 Pa, and a target power of 150 W; Step 10: Close the chamber door of the Cr metal target, open the chamber door of the TiCr alloy target, and deposit a TiCrN film under the conditions of a voltage of 50-150 V, a pressure of 1-2 Pa, and a target power of 150 W. Step 11: Close the chamber door of the TiCr alloy target, open the chamber door of the Ti alloy target, and deposit a TiN film under the conditions of a voltage of 50-150 V, a pressure of 1-2 Pa, and a target power of 150 W; Step 12: Close the chamber door of the Ti metal target, open the chamber door of the TiNb alloy target, and deposit a TiNbN film under the conditions of a voltage of 50-150 V, a pressure of 1-2 Pa, and a target power of 150 W. Step 13: Close the nitrogen valve, lower the temperature to below 80°C, close the argon valve, turn off the vacuum system, wait for cooling to room temperature, and take out the sample to complete the coating.

2. The method for preparing a medical biogradient hard coating according to claim 1, characterized in that: The thickness of the Cr film layer obtained in step 8 is 0.5 μm, and the deposition temperature is between 300 and 400° C.

3. The method for preparing a medical biogradient hard coating according to claim 1, characterized in that: The thickness of the CrN film layer obtained in step 9 is 1 μm, and the deposition temperature is between 300° C. and 400° C.

4. The method for preparing a medical biogradient hard coating according to claim 1, characterized in that: The thickness of the TiCrN film obtained in step 10 is 1 μm, and the deposition temperature is between 300° C. and 400° C.

5. The method for preparing a medical biogradient hard coating according to claim 1, characterized in that: The thickness of the TiN film obtained in step 11 is 1 μm, and the deposition temperature is between 300° C. and 400° C.

6. The method for preparing a medical biogradient hard coating according to claim 1, characterized in that: The thickness of the TiNbN film layer obtained in step 12 is 1.5 μm, and the deposition temperature is between 300° C. and 400° C.

7. The method for preparing a medical biogradient hard coating according to claim 1, characterized in that: In the step 1, the ratio of alloy elements in the TiCr alloy target is Ti:Cr=80:20 (at%).

8. The method for preparing a medical biogradient hard coating according to claim 1, characterized in that: In the step 1, the ratio of alloy elements in the TiNb alloy target is Ti:Nb=70:30 (at%).

Images