A method for surface treatment of orthopedic implants based on femtosecond laser

Abstract

The present invention relates to a method for surface treatment of orthopedic implants based on femtosecond laser. The surface treatment method comprises the following steps: cleaning and drying the surface of the orthopedic implant substrate; performing femtosecond laser treatment on the surface of the orthopedic implant substrate to form regularly arranged microstructures on the substrate surface; wherein, the orthopedic implant substrate comprises a metal substrate, a bioceramic substrate and a polymer material substrate; the microstructures include one or more of grooves, dot matrices or grids; performing plasma spraying of a biological coating on the surface of the orthopedic implant substrate after femtosecond laser treatment to finally obtain a surface-modified orthopedic implant; wherein, the biological coating comprises a titanium coating and a hydroxyapatite coating. Compared with the prior art, the present invention significantly improves the bonding force between the plasma-sprayed biological coating and the orthopedic implant substrate, and broadens the types of applications of the orthopedic implant substrate.

Description

Technical Field

[0001] The present invention belongs to the technical field of surface treatment, and particularly relates to a method for surface treatment of orthopedic implants based on femtosecond laser. Background Art

[0002] The problem of repair and replacement of large-scale bone defects caused by diseases, traumas, aging, etc. is an important topic that has been continuously studied by humans for centuries. However, so far, the clinical treatment of large-scale bone defects remains a world problem. Using orthopedic implants to reconstruct the structure and function of bone tissue at the defect site is the main treatment method in modern orthopedics.

[0003] The development of orthopedic implants has gone through several stages. The first-generation implants were mainly made of metals, such as titanium alloys and stainless steels. However, the rigidity and weight of these metal materials limit their application scope. The second-generation implants used absorbable materials, such as polylactic acid (PLA) and poly(lactic-co-glycolic acid) (PLGA), which can degrade and be gradually replaced by newly formed bone. Recently, the third-generation implants have introduced bioactive materials, such as hydroxyapatite (HA) coatings and growth factor controlled-release systems.

[0004] Preparing a bio-coating on the surface of orthopedic implants is a commonly used and very effective method. The bio-coating can promote bone ingrowth or bone ongrowth, so the bonding strength between the coating and the substrate is particularly important. If the bonding strength between the coating and the substrate is insufficient, the peeled-off coating debris may enter the joint surface, forming abrasive wear, which greatly accelerates the wear of mating components such as ball sockets, and may also damage the surrounding bones, leading to osteolysis and aseptic loosening, and ultimately causing the implant to fail.

[0005] Plasma spraying bio-coatings are preparation methods approved by the FDA for clinical applications and have decades of clinical experience. Currently, porous titanium coatings and hydroxyapatite (HA) coatings are widely used clinically, and the substrates are mainly metals such as titanium, titanium alloys, and cobalt-chromium-molybdenum. Currently, the pretreatment for plasma spraying is mainly sandblasting, which can increase the surface area of the substrate and enable the plasma spraying coating to form a mechanical bond with the substrate. For example, CN118109773A discloses a high-entropy alloy coating for improving the mechanical properties and biocompatibility of titanium alloys and its preparation method, specifically ultrasonic cleaning and sandblasting treatment on a titanium alloy substrate, and then depositing a high-entropy alloy coating on the treated substrate using an atmospheric plasma spraying device; CN114099777A discloses a multi-layer active coating for orthopedic implants and its preparation method, which also introduces an active coating by plasma spraying or electrochemical deposition after sandblasting treatment of the orthopedic implant.

[0006] However, the bonding between the substrate after sandblasting and the coating is physical, and the bonding strength is often not strong, which easily leads to coating peeling. In addition, further cleaning is often required after sandblasting to remove the residual abrasive. If a gas gun is used for cleaning, the residual abrasive is not easy to clean completely; if pickling is used for cleaning, it is easy to generate additional chemical pollution. In addition, the existing sandblasting can only be used on the surface of metals (such as titanium and titanium alloys), which greatly limits the application of plasma spraying on the substrates of orthopedic implants made of different materials.

[0007] Therefore, there is still a need to develop a new surface treatment method for orthopedic implants to improve the bonding strength between the substrate of orthopedic implants and the biological coating. Summary of the Invention

[0008] The purpose of the present invention is to provide a surface treatment method for orthopedic implants based on femtosecond laser to overcome the defect that the bonding strength between the biological coating and the matrix of orthopedic implants in the existing technology is not strong.

[0009] The purpose of the present invention can be achieved by the following technical solutions:

[0010] The present invention first provides a surface treatment method for orthopedic implants based on femtosecond laser, and the surface treatment method includes the following steps:

[0011] S1: Clean and dry the surface of the substrate of the orthopedic implant;

[0012] S2: Perform femtosecond laser treatment on the surface of the substrate of the orthopedic implant to form regularly arranged microstructures on the substrate surface;

[0013] Among them, the substrate of the orthopedic implant includes a metal substrate, a bioceramic substrate, and a polymer material substrate;

[0014] The energy of the femtosecond laser is 40 - 150 μJ, the wavelength of the femtosecond laser is 1000 - 1100 nm, and the pulse width of the femtosecond laser is 245 - 255 fs;

[0015] The microstructures include one or more of grooves, dot matrices, or grids;

[0016] S3: Perform plasma spraying of a biological coating on the surface of the substrate of the orthopedic implant after femtosecond laser treatment to finally obtain a surface-modified orthopedic implant;

[0017] Among them, the biological coating includes a titanium (Ti) coating and a hydroxyapatite (HA) coating.

[0018] Furthermore, the metal substrate includes titanium and titanium alloys. Titanium and titanium alloys have good biocompatibility with human bones, can reduce rejection reactions, and at the same time have sufficient mechanical strength and corrosion resistance to withstand the challenges of the in-vivo environment.

[0019] Furthermore, the bioceramic substrate includes an alumina ceramic substrate and a zirconia ceramic substrate. Alumina and zirconia ceramic materials are commonly used to manufacture components such as the femoral head and acetabular cup of artificial joints. The selection of these materials can reduce wear particles generated on the joint surface, lower the risk of periprosthetic osteolysis and prosthesis loosening, thereby extending the service life of artificial joints.

[0020] Furthermore, the polymer material substrate includes a polyetheretherketone (PEEK) substrate. PEEK has good corrosion resistance, fatigue resistance, self-lubricity, chemical stability, and radiopacity. These properties make PEEK an ideal material for orthopedic implants and can be applied in fields such as spinal fusion cages, trauma internal fixation devices, and femoral stem prostheses.

[0021] Furthermore, in step S1, the cleaning is performed by ultrasonic cleaning and / or plasma cleaning.

[0022] Furthermore, in step S1, the drying temperature is 50 - 70 °C.

[0023] Furthermore, in step S2, the power of the femtosecond laser is 0.1 - 20 W.

[0024] Furthermore, in step S2, the scanning speed of the femtosecond laser is 0.5 - 3 m / min.

[0025] Furthermore, in step S2, the spot diameter of the femtosecond laser is 20 - 50 µm.

[0026] Furthermore, in step S2, the spot pitch of the femtosecond laser is 80 - 200 µm.

[0027] Furthermore, in step S2, the width of the groove is 20 - 80 µm, and the pitch is 80 - 200 µm.

[0028] Furthermore, in step S2, the hole size of the dot matrix is 20 - 80 µm, and the pitch is 50 - 100 µm.

[0029] Furthermore, in step S2, the width of the grid is 20 - 80 µm, and the pitch is 80 - 200 µm.

[0030] Furthermore, in step S2, after femtosecond laser treatment, the surface roughness of the metal substrate and the bioceramic substrate is not less than 8 µm.

[0031] Furthermore, in step S2, after femtosecond laser treatment, the surface roughness of the polymer material substrate is not less than 20 µm.

[0032] Furthermore, in step S2, the orthopedic implant substrate after femtosecond laser treatment can be cleaned by ultrasonic cleaning, and the cleaning medium includes solvents such as pure water and isopropyl alcohol.

[0033] Furthermore, in step S3, the plasma spraying gun has a power of 40-50 kW, a powder feeding amount of 15-25 g / min, and a spraying distance of 150-250 mm.

[0034] Furthermore, in step S3, when the biological coating is a titanium coating, the plasma spraying is performed in a vacuum environment.

[0035] Furthermore, in step S3, when the biological coating is a hydroxyapatite coating, the plasma spraying is performed in an atmospheric environment.

[0036] Furthermore, in step S3, when the biological coating is a titanium coating, the thickness of the coating is 150-600 µm.

[0037] Furthermore, in step S3, when the biological coating is a hydroxyapatite coating, the thickness of the coating is 20-100 µm.

[0038] Since the thicker the plasma sprayed coating is, the weaker the bonding force is, the thickness of the coating should be controlled within an appropriate range.

[0039] The present invention also provides a surface modified orthopedic implant obtained by the surface treatment method.

[0040] The surface modified orthopedic implant of the invention consists of an orthopedic implant substrate and a biological coating attached to the surface of the orthopedic implant substrate.

[0041] Furthermore, when the biological coating is a titanium coating, the bonding force between the biological coating and the orthopedic implant substrate is not less than 25 MPa.

[0042] Furthermore, when the biological coating is a hydroxyapatite coating, the bonding force between the biological coating and the orthopedic implant substrate is not less than 50 MPa.

[0043] Furthermore, when the biological coating is a hydroxyapatite coating, the crystallinity of hydroxyapatite in the hydroxyapatite coating is 60%-70%.

[0044] Furthermore, the surface modified orthopedic implants include but are not limited to titanium alloy sprayed with HA coating, titanium alloy sprayed with Ti coating, alumina ceramic sprayed with Ti coating, zirconia ceramic sprayed with Ti coating and PEEK sprayed with Ti coating. The specific orthopedic implant substrate and biological coating can be selected according to actual needs.

[0045] The femtosecond laser technology used in the present invention is different from the long-wavelength laser that induces molecular vibration to cause thermal effects. Due to its extremely low pulse width, the femtosecond laser can obtain extremely high peak power with relatively low pulse energy, triggering multi-photon absorption and achieving the purpose of material removal through ultrafast non-linear absorption. The thermal effect during the femtosecond laser processing can be ignored (i.e., cold processing), enabling spatial selective manipulation of the microstructure.

[0046] The plasma spraying surface modification process used in the present invention is to feed the powder to be sprayed into the plasma flame, so that the powder is melted or semi-melted, and then deposited on the substrate surface to form a coating at a very high speed through the plasma gas. The femtosecond laser of the present invention, as a pretreatment step for plasma spraying biological coatings, can ensure the bonding strength of the biological coatings after plasma spraying, which is due to the synergistic effect caused by the increase in the surface area of the substrate, mechanical grip, and changes in surface physical and chemical properties.

[0047] During the high-speed particle impact process, once the droplet impacts the substrate, it begins to spread. The melted particles start to expand radially outward, and solidification immediately occurs at the bottom of the droplet, resulting in a deceleration of the liquid movement. The droplet reaches a static state after a limited diffusion time. Due to the high compression experienced by the droplet during impact, a shock wave is generated and propagates upward inside the droplet. Therefore, the elastic energy on the compressed liquid is gradually converted into the kinetic energy of the lateral flow. If the solidification rate and diffusion speed on the flat surface are inconsistent, splashing will occur.

[0048] The adhesion strength is mainly controlled by the contact adhesion area. A large contact area increases the energy release rate at the interface. The adhesion of the plasma spraying coating on the textured substrate will be affected by the pattern geometry. By laser surface texturing, the surface contact area of the substrate is changed, promoting a larger adhesion area.

[0049] At the same time, through optimized femtosecond laser process parameters, the surface wettability of the substrate can be effectively improved, and the surface wettability of the substrate shows superhydrophilic characteristics. When the molten particles impact the substrate, it can better make the molten particles spread out, reduce splashing, better combine with the substrate, and improve the bonding strength between the biological coating and the orthopedic implant substrate.

[0050] Compared with the prior art, the present invention has the following beneficial effects:

[0051] (1) The present invention uses the femtosecond laser processing technology for pretreatment of common orthopedic implants such as metal substrates, bioceramic substrates, or polymer material substrates before plasma spraying, which can significantly improve the bonding strength between the plasma spraying biological coating and the orthopedic implant substrate.

[0052] (2) The femtosecond laser processing technology of the present invention can be applied not only to common metal substrates, but also to the surfaces of bioceramic substrates such as alumina ceramics and zirconia ceramics, and polymer material substrates such as polyetheretherketone. A biological coating meeting the bonding strength requirements can be obtained on the surfaces of various common orthopedic implant substrates, greatly broadening the types of applications of orthopedic implant substrates.

[0053] (3) The present invention uses femtosecond laser as a pretreatment step for plasma spraying biological coatings. Through the synergistic effect caused by the increase in the surface area of the substrate, mechanical grip force, and changes in surface physical and chemical properties, it is ensured that the biological coating after plasma spraying has good bonding strength and will not easily peel off, so as to meet the bonding strength requirements of orthopedic implants in actual use.

[0054] (4) By optimizing the femtosecond laser process parameters, the present invention can effectively improve the surface wettability of the substrate. When the molten particles impact the substrate, it can better spread the molten particles, reduce splashing, and better combine with the substrate, thereby improving the bonding strength between the biological coating and the orthopedic implant substrate.

[0055] (5) The femtosecond laser of the present invention is in a cold processing mode, without subsequent polishing or chemical treatment, and no additional pollution or metal waste is generated during the processing process. It is a very environmentally friendly processing method and can be widely applied to the processing of the surfaces of orthopedic implant substrates.

[0056] (6) Through the femtosecond laser process, the present invention can significantly improve the bonding strength between the biological coating and the orthopedic implant substrate, reduce the wear impact of the peeled coating debris on the implant and the bone, and is expected to extend the service life of orthopedic implants. Brief Description of the Drawings

[0057] Figure 1 It is a flow schematic diagram of the surface treatment method of orthopedic implants based on femtosecond laser of the present invention.

[0058] Figure 2 It is a schematic diagram of the microstructure of the titanium alloy surface after femtosecond laser treatment in Example 1 of the present invention.

[0059] Figure 3 It is a schematic diagram of the hydrophilic property of the titanium alloy surface after femtosecond laser treatment in Example 1 of the present invention.

[0060] Figure 4 It is a schematic diagram of the microstructure of the titanium alloy surface after femtosecond laser treatment in Example 2 of the present invention.

[0061] Figure 5 It is a schematic diagram of the microstructure of the alumina ceramic surface after femtosecond laser treatment in Example 3 of the present invention.

[0062] Figure 6Schematic diagram of the microstructure on the surface of zirconia ceramics after femtosecond laser treatment in Example 4 of the present invention.

[0063] Figure 7 Schematic diagram of the microstructure on the surface of PEEK after femtosecond laser treatment in Example 5 of the present invention.

[0064] Figure 8 Microscope image of the surface of titanium alloy after sandblasting in Comparative Example 1.

[0065] Figure 9 Microscope images of the surface of alumina ceramic substrate before and after sandblasting in Comparative Example 3.

[0066] Figure 10 Schematic diagram of the peeling of the Ti coating from the surface of the alumina ceramic substrate in Comparative Example 3.

[0067] Figure 11 Microscope images of the surface of zirconia ceramic substrate before and after sandblasting in Comparative Example 4.

[0068] Figure 12 Microscope image of the surface of PEEK substrate after sandblasting in Comparative Example 5. Detailed implementation manners

[0069] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. These embodiments are implemented on the premise of the technical solution of the present invention, and detailed implementation manners and specific operation processes are given, but the protection scope of the present invention is not limited to the following embodiments.

[0070] Unless otherwise specified, the reagents, methods, instruments, and equipment used in the present invention are conventional reagents, methods, instruments, and equipment in the art. Unless otherwise specified, the reagents and materials used in the following examples are all commercially available.

[0071] The present invention specifically relates to a surface treatment method for orthopedic implants based on femtosecond laser. The surface treatment method refers to Figure 1 , and includes the following steps:

[0072] S1: Clean and dry the surface of the orthopedic implant substrate;

[0073] S2: Perform femtosecond laser treatment on the surface of the orthopedic implant substrate to form regularly arranged microstructures on the substrate surface;

[0074] S3: Perform plasma spraying of a bio-coating on the surface of the orthopedic implant substrate after femtosecond laser treatment to finally obtain a surface-modified orthopedic implant.

[0075] The surface-modified orthopedic implants in the following examples are all obtained based on the above surface treatment method.

[0076] Example 1

[0077] This embodiment provides a titanium alloy orthopedic implant sprayed with an HA coating and its specific surface treatment method. The specific steps are as follows:

[0078] (1) First, ultrasonically clean the polished titanium alloy substrate with isopropyl alcohol for 10 minutes, then ultrasonically clean it with pure water for 10 minutes, and then place it in a drying oven at 60 °C for drying.

[0079] (2) Perform femtosecond laser treatment on the surface of the titanium alloy substrate in an atmospheric environment to form regularly arranged grid microstructures (as Figure 2 shown).

[0080] In this embodiment, the specific parameters of the femtosecond laser are as follows: the energy is 40 μJ, the spot diameter is 50 μm; the spot spacing is 200 μm, and the scanning speed is 2.5 m / min. The wavelength of the femtosecond laser is 1050 nm, and the pulse width is 250 fs.

[0081] In this embodiment, the width of the grooves of the grid microstructures is about 60 μm, and the centerline distance between the grooves is about 200 μm.

[0082] The surface roughness Ra of the titanium alloy before femtosecond laser treatment is 1.231 μm, and the surface roughness Ra of the titanium alloy after femtosecond laser treatment is 9.624 μm.

[0083] (3) Ultrasonically clean the titanium alloy substrate after femtosecond laser treatment in pure water for 10 minutes, and then dry it in a drying oven at 60 °C.

[0084] (4) Perform atmospheric plasma spraying of an HA coating on the surface of the titanium alloy substrate after femtosecond laser treatment. The thickness of the HA coating is about 100 μm, and finally, a surface-modified titanium alloy orthopedic implant sprayed with an HA coating is obtained.

[0085] In this embodiment, the specific parameters of plasma spraying are as follows: the equipment used to prepare the HA coating is an atmospheric plasma spraying equipment, voltage: 60 V; plasma gun power: 45 kw; argon gas flow rate: 20 sccm; helium gas: 30 sccm; powder feeding rate: 15 g / min; spraying distance: 200 mm. The HA crystallinity in the prepared HA coating is 62.7%, there is no other crystalline phase, and the rest is amorphous phase.

[0086] Drop water droplets on the surface of the titanium alloy substrate after femtosecond laser treatment in this embodiment, as Figure 3As shown, it can be found that the water droplets spread rapidly, indicating that the wettability of the titanium alloy substrate after femtosecond laser treatment shows superhydrophilic characteristics. In this embodiment, by optimizing the femtosecond laser process parameters, the surface wettability of the substrate is improved. When the molten particles impact the substrate, the molten particles can spread better, reducing splashing, and then better combining with the substrate to improve the bonding strength between the coating and the substrate.

[0087] Example 2

[0088] This embodiment provides a titanium alloy orthopedic implant with a sprayed Ti coating and its specific surface treatment method, the steps are as follows:

[0089] (1) The polished titanium alloy substrate is first ultrasonically cleaned with isopropyl alcohol for 10 min, then ultrasonically cleaned with pure water for 10 min, and then placed in a drying oven at 60 °C for drying.

[0090] (2) Femtosecond laser treatment is carried out on the surface of the titanium alloy substrate under atmospheric environment to form regularly arranged groove microstructures (as Figure 4 shown).

[0091] In this embodiment, the specific parameters of the femtosecond laser are as follows: the energy is 150 μJ, the spot diameter is 20 μm; the spot spacing is 80 μm, and the scanning speed is 2.5 m / min. The wavelength of the femtosecond laser is 1050 nm, and the pulse width is 250 fs.

[0092] In this embodiment, the width of the groove microstructure is 35 μm, and the center distance between the grooves is 80 μm.

[0093] The surface roughness Ra of the titanium alloy before femtosecond laser treatment is 1.342 μm, and the surface roughness Ra of the titanium alloy after femtosecond laser treatment is 10.392 μm.

[0094] (3) The titanium alloy substrate after femtosecond laser treatment is ultrasonically cleaned in pure water for 10 min, and then dried in a drying oven at 60 °C.

[0095] (4) The surface of the titanium alloy substrate after femtosecond laser treatment is subjected to atmospheric plasma spraying of a Ti coating, and the thickness of the Ti coating is 500 μm, and finally a titanium alloy orthopedic implant with a surface-modified sprayed Ti coating is obtained.

[0096] In this embodiment, the specific parameters of plasma spraying are as follows: The equipment used for preparing the Ti coating is a vacuum plasma spraying equipment. Vacuum degree: The vacuum degree is pumped to 0.06 mbar, and then argon gas is introduced until the vacuum degree reaches 200 mbar; Voltage: 60 V; Plasma spray gun power: 50 kw; Argon gas flow rate: 20 sccm; Powder feeding rate: 20 g / min; Spraying distance: 200 mm. The prepared Ti coating is a pure titanium layer, and the specific composition is titanium.

[0097] Example 3

[0098] This embodiment provides an alumina ceramic orthopedic implant with a sprayed Ti coating and its specific surface treatment method, and the steps are as follows:

[0099] (1) The polished alumina ceramic substrate is first ultrasonically cleaned with isopropyl alcohol for 10 min, then ultrasonically cleaned with pure water for 10 min, and then placed in a drying oven at 60 °C for drying.

[0100] (2) Femtosecond laser treatment is carried out on the surface of the alumina ceramic substrate under atmospheric environment to form a regularly arranged grid microstructure (as Figure 5 shown).

[0101] In this embodiment, the specific parameters of the femtosecond laser are as follows: The energy is 100 μJ, the spot diameter is 35 μm; The spot spacing is 100 μm, and the scanning speed is 0.5 m / min.

[0102] In this embodiment, the groove width dimension of the grid microstructure is 60 μm, and the center line distance between grooves is 200 μm.

[0103] In this embodiment, the surface roughness Ra of the alumina ceramic substrate before pretreatment is 1.618 μm, and the surface roughness Ra after femtosecond laser treatment is 12.366 μm, and the surface roughness has been significantly improved.

[0104] (3) The femtosecond laser-treated alumina ceramic substrate is ultrasonically cleaned with pure water for 10 min, and then dried in a drying oven at 60 °C.

[0105] (4) A Ti coating is vacuum plasma sprayed on the surface of the femtosecond laser-treated alumina ceramic substrate. The thickness of the Ti coating is 500 μm, and finally an alumina ceramic orthopedic implant with a surface-modified sprayed Ti coating is obtained.

[0106] In this embodiment, the specific parameters of plasma spraying are as follows: The equipment used for preparing the Ti coating is a vacuum plasma spraying equipment. Vacuum degree: The vacuum degree is pumped to 0.06 mbar, and then argon gas is introduced until the vacuum degree reaches 200 mbar; Voltage: 60 V; Plasma spray gun power: 50 kw; Argon gas flow rate: 20 sccm; Powder feeding rate: 20 g / min; Spraying distance: 200 mm. The prepared Ti coating is a pure titanium layer, and the specific composition is titanium.

[0107] Example 4

[0108] This embodiment provides a zirconia ceramic orthopedic implant with a sprayed Ti coating and its specific surface treatment method, and the steps are as follows:

[0109] (1) The polished zirconia ceramic substrate is first ultrasonically cleaned with isopropanol for 10 min, then ultrasonically cleaned with pure water for 10 min, and then placed in a drying oven at 60 °C for drying.

[0110] (2) Femtosecond laser treatment is carried out on the surface of the zirconia ceramic substrate under atmospheric environment to form a regularly arranged porous lattice microstructure (as Figure 6 shown).

[0111] In this embodiment, the specific parameters of the femtosecond laser are as follows: The energy is 140 μJ, the spot diameter is 40 μm; The spot spacing is 150 μm, and the scanning speed is 2 m / min.

[0112] In this embodiment, the pore diameter range of the lattice microstructure is between 20 - 40 μm, and the distance between the pore centers is about 80 μm.

[0113] In this embodiment, the surface roughness Ra of the zirconia ceramic substrate before pretreatment is 1.009 μm, and the surface roughness Ra after femtosecond laser treatment is 10.777 μm.

[0114] (3) The femtosecond laser-treated zirconia ceramic substrate is ultrasonically cleaned with pure water for 10 min, and then dried in a drying oven at 60 °C.

[0115] (4) A Ti coating is vacuum plasma sprayed on the surface of the femtosecond laser-treated zirconia ceramic substrate. The thickness of the Ti coating is 500 μm, and finally a zirconia ceramic orthopedic implant with a surface-modified sprayed Ti coating is obtained.

[0116] In this embodiment, the specific parameters of plasma spraying are as follows: The equipment used to prepare the Ti coating is a vacuum plasma spraying equipment. Vacuum degree: The vacuum degree is pumped to 0.06 mbar, and then argon is introduced until the vacuum degree reaches 200 mbar; Voltage: 60 V; Plasma spray gun power: 50 kw; Argon gas flow rate: 20 sccm; Powder feeding rate: 20 g / min; Spraying distance: 200 mm. The prepared Ti coating is a pure titanium layer, and the specific composition is titanium.

[0117] Example 5

[0118] This embodiment provides a PEEK orthopedic implant with a sprayed Ti coating and its specific surface treatment method, and the steps are as follows:

[0119] (1) The polished PEEK substrate is first ultrasonically cleaned with isopropanol for 10 min, then ultrasonically cleaned with pure water for 10 min, and then placed in a drying oven at 60 °C for drying.

[0120] (2) Femtosecond laser treatment is carried out on the surface of the PEEK substrate in an argon environment to form regularly arranged groove microstructures (as Figure 7 shown).

[0121] In this embodiment, the specific parameters of the femtosecond laser are as follows: The energy is 50 μJ, the spot diameter is 40 μm; The spot spacing is 300 μm, and the scanning speed is 2.5 m / min.

[0122] In this embodiment, the width dimension of the groove microstructure is 35 μm, and the center distance between grooves is 80 μm.

[0123] In this embodiment, the surface roughness Ra of the PEEK substrate is 3.684 μm, and the surface roughness Ra after femtosecond laser treatment is 26.395 μm.

[0124] (3) The PEEK substrate after femtosecond laser treatment is ultrasonically cleaned with pure water for 10 min, and then dried in a drying oven at 60 °C.

[0125] (4) The surface of the PEEK substrate after femtosecond laser treatment is subjected to atmospheric plasma spraying of a Ti coating, and the thickness of the Ti coating is 500 μm, and finally a PEEK orthopedic implant with a surface-modified sprayed Ti coating is obtained.

[0126] In this embodiment, the specific parameters of plasma spraying are as follows: The equipment used to prepare the Ti coating is a vacuum plasma spraying equipment. Vacuum degree: The vacuum degree is pumped to 0.06 mbar, and then argon is introduced until the vacuum degree reaches 200 mbar; Voltage: 60 V; Plasma spray gun power: 50 kw; Argon gas flow rate: 20 sccm; Powder feeding rate: 20 g / min; Spraying distance: 200 mm.

[0127] Comparative Example 1:

[0128] This comparative example provides a specific pretreatment method for sandblasting a titanium alloy substrate before plasma spraying a HA coating, and the steps are as follows:

[0129] (1) The polished titanium alloy substrate was first ultrasonically cleaned with isopropyl alcohol for 10 min, then ultrasonically cleaned with pure water for 10 min, and then placed in a drying oven at 60 °C for drying.

[0130] (2) Sandblasting was carried out using alumina abrasive of F24 type, and the sandblasting parameters were as follows: the sandblasting pressure was 4 bar; the sandblasting distance was 15 cm, and sandblasting was carried out until the surface was uniform. The surface morphology after sandblasting was as Figure 8 shown.

[0131] The roughness Ra of the titanium alloy substrate before sandblasting was 1.213 µm, and the surface roughness Ra of the alumina after sandblasting was only 4.512 µm, which was much lower than the surface roughness of 10.392 µm after femtosecond laser treatment.

[0132] (3) The sandblasted titanium alloy substrate was cleaned with a compressed air gun.

[0133] (4) A HA coating with a thickness of 100 µm was plasma sprayed on the surface of the sandblasted titanium alloy substrate.

[0134] Comparative Example 2:

[0135] This comparative example provides a specific pretreatment method for sandblasting a titanium alloy substrate before plasma spraying a Ti coating, and the steps are as follows:

[0136] (1) The polished titanium alloy substrate was first ultrasonically cleaned with isopropyl alcohol for 10 min, then ultrasonically cleaned with pure water for 10 min, and then placed in a drying oven at 60 °C for drying.

[0137] (2) Sandblasting was carried out using alumina abrasive of F24 type, and the sandblasting parameters were as follows: the sandblasting pressure was 4 bar; the sandblasting distance was 15 cm, and sandblasting was carried out until the surface was uniform.

[0138] (3) The sandblasted titanium alloy substrate was cleaned with a compressed air gun.

[0139] (4) A Ti coating with a thickness of 500 µm was plasma sprayed on the surface of the sandblasted titanium alloy substrate.

[0140] Comparative Example 3:

[0141] This comparative example sandblasts an alumina ceramic substrate before plasma spraying a Ti coating.

[0142] The sandblasting parameters are as follows: the sandblasting pressure is 4 bar; the sandblasting distance is 15 cm, and the sandblasting is uniform on the surface. The sand material type is alumina sand, and the surface morphology of the alumina after sandblasting is as Figure 9 shown.

[0143] The roughness Ra of the alumina substrate before sandblasting is 1.618 µm, and the roughness Ra of the alumina surface after sandblasting is only 2.993 µm, which is much lower than the surface roughness of 12.366 µm after femtosecond laser treatment.

[0144] In addition, after plasma spraying the titanium coating, with only slight manual force, the titanium coating on the surface of the alumina ceramic substrate will directly peel off (as Figure 10 shown), indicating that the bonding force between the alumina ceramic substrate after sandblasting and the titanium coating is weak and cannot meet the corresponding bonding force standard. Therefore, sandblasting is not suitable for pre-treatment modification of the surface of the alumina ceramic substrate.

[0145] Comparative Example 4:

[0146] In this comparative example, the zirconia ceramic substrate was sandblasted before plasma spraying the Ti coating. The sandblasting parameters are as follows: the sandblasting pressure is 4 bar; the sandblasting distance is 15 cm, and the sandblasting is uniform on the surface. The sand material type is zirconia sand, and the surface morphology of the alumina after sandblasting is as Figure 11 shown.

[0147] In this example, the roughness Ra of the zirconia substrate before sandblasting is 1.009 µm, and the roughness Ra of the zirconia surface after sandblasting is 2.210 µm, which is much lower than the surface roughness of 10.777 µm after femtosecond laser treatment.

[0148] Observed under a 100-fold microscope, it was found that the surface morphology of the zirconia ceramic substrate before and after sandblasting did not change much, indicating that sandblasting treatment cannot achieve the expected surface modification effect on the zirconia ceramic substrate.

[0149] In addition, after plasma spraying the titanium coating, with only slight manual force, the titanium coating will also directly peel off from the zirconia ceramic substrate, indicating that the bonding force between the zirconia ceramic substrate after sandblasting and the titanium coating is weak and cannot meet the corresponding bonding force standard. Therefore, sandblasting is not suitable for pre-treatment surface modification of the surface of the zirconia ceramic substrate either.

[0150] Comparative Example 5:

[0151] In this comparative example, the PEEK substrate was sandblasted before plasma spraying the Ti coating.

[0152] The sandblasting parameters are as follows: the sandblasting pressure is 4 bar; the sandblasting distance is 15 cm, and the sandblasting is uniform on the surface. The sand material model is zirconia sand material, and the surface morphology of the alumina after sandblasting is as Figure 12 shown.

[0153] The roughness Ra of the PEEK substrate before sandblasting is 3.684 µm, and the surface roughness Ra of the PEEK substrate after sandblasting is 4.616 µm, which is much lower than the surface roughness of 26.395 µm after femtosecond laser treatment. Sandblasting treatment also cannot achieve the expected surface modification effect on the PEEK substrate.

[0154] The summary of the surface roughness Ra of the orthopedic implant substrates after femtosecond laser treatment in Examples 1-5 and the orthopedic implant substrates after sandblasting treatment in Comparative Examples 1-5 of the present invention is shown in Table 1.

[0155] Table 1 Summary of the surface roughness of orthopedic implant substrates

[0156]

[0157] As can be seen from Table 1, fine micro-nano structures are formed on the surface of the orthopedic implant substrate after femtosecond laser treatment, thereby increasing the surface roughness of the substrate. However, there are no controllable microscopic morphological changes in the orthopedic implant substrate after sandblasting treatment, and the surface roughness is not significantly different from that before treatment.

[0158] The increase in surface roughness indicates that the substrate surface has a larger contact area, and a sufficient contact area will further increase the energy release rate at the interface. The adhesion of the plasma spray coating on the textured substrate is affected by the pattern geometry. The surface contact area of the substrate is changed by laser surface texturing, enhancing the mechanical interlocking effect between the biocoating and the substrate, thereby improving the bonding strength between the biocoating and the orthopedic implant substrate. However, the random impact of sandblasting particles during sandblasting treatment only produces macroscopic roughness and lacks controllable microscopic morphology, which may lead to a limited increase in surface area, and thus the surface roughness after sandblasting treatment is not significantly different from that before sandblasting treatment.

[0159] In accordance with the regulations, the present invention further tests the bonding strength between the substrate and the coating after plasma spraying the biocoating on Examples 1-5 and Comparative Examples 1-5. The bonding strength requirements, standards and test methods of the corresponding coatings are shown in Table 2, and the test results of the bonding strength between the substrate and the coating are summarized in Table 3.

[0160] Table 2 Bonding strength requirements for plasma-sprayed titanium coatings and HA coatings

[0161]

[0162] Table 3 Test results of the bonding strength of plasma-sprayed titanium coatings and HA coatings

[0163]

[0164] The results show that for metal materials such as titanium alloy, the tensile strength of the HA coating after sandblasting is 46.36 MPa; while after the titanium alloy is treated by femtosecond laser, the tensile strength of the HA coating can reach 71 MPa, which is 53.6% higher than that of the sandblasted one, indicating that the bonding force between the titanium alloy and the HA coating is significantly improved after femtosecond laser treatment.

[0165] For bioceramic materials such as alumina and zirconia ceramics, sandblasting cannot effectively change the morphology of the ceramic matrix, and the Ti coating is extremely easy to peel off after plasma spraying, with weak bonding force and unable to conduct bonding force testing. However, after alumina ceramics and zirconia ceramics are treated by femtosecond laser, a biocoating can be well formed on the surface of the substrate through plasma spraying process, and the tensile strength of the Ti coating can be as high as 34 MPa, far exceeding the relevant standard requirements.

[0166] For medical polymer materials such as PEEK, the tensile strength of the titanium coating formed by plasma spraying after sandblasting is 27.791 MPa. After being treated by femtosecond laser, the tensile strength of the titanium coating is 28.553 MPa, with a slight increase in tensile strength, which can fully meet the corresponding standard requirements.

[0167] In summary, the present invention uses femtosecond laser micro-nano processing technology to perform surface treatment on common orthopedic implants such as titanium alloy, alumina ceramics, zirconia ceramics, and PEEK before plasma spraying biocoatings. Through synergistic mechanisms such as improving surface wettability and increasing surface contact and adhesion area, the bonding force between the biocoating and the orthopedic implant substrate can be significantly improved, reducing the wear effect of the peeled coating debris on the implant and bone, and is expected to extend the service life of orthopedic implants.

[0168] The above description of the embodiments is to enable those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative labor. Therefore, the present invention is not limited to the above embodiments, and the improvements and modifications made by those skilled in the art without departing from the scope of the present invention should be within the protection scope of the present invention.

Claims

1. A method for surface treatment of orthopedic implants based on femtosecond laser, characterized in that, The surface treatment method includes the following steps: S1: Clean and dry the surface of the orthopedic implant substrate; S2: Perform femtosecond laser treatment on the surface of the orthopedic implant substrate to form regularly arranged microstructures on the substrate surface to improve surface wettability and increase the surface contact area; The energy of the femtosecond laser is 40 - 150 µJ, the wavelength of the femtosecond laser is 1000 - 1100 nm, the pulse width of the femtosecond laser is 245 - 255 fs, and the microstructures include one or more of grooves, dot matrices or grids; S3: Plasma spray a biocoating on the surface of the orthopedic implant substrate after femtosecond laser treatment to finally obtain a surface-modified orthopedic implant; The surface-modified orthopedic implant consists of an orthopedic implant substrate and a biocoating attached to the surface of the orthopedic implant substrate; The orthopedic implant substrate includes a metal substrate, a bioceramic substrate and a polymer material substrate. The metal substrate includes titanium and titanium alloys, the bioceramic substrate includes an alumina ceramic substrate and a zirconia ceramic substrate, and the polymer material substrate includes a polyetheretherketone substrate; the surface roughness of the metal substrate and the bioceramic substrate after femtosecond laser treatment is not less than 8 µm, and the surface roughness of the polymer material substrate after femtosecond laser treatment is not less than 20 µm; The biocoating includes a titanium coating and a hydroxyapatite coating; when the biocoating is a titanium coating, the bonding strength between the biocoating and the orthopedic implant substrate is not less than 25 MPa; when the biocoating is a hydroxyapatite coating, the bonding strength between the biocoating and the orthopedic implant substrate is not less than 50 MPa.

2. The surface treatment method of an orthopedic implant based on femtosecond laser according to claim 1, wherein In step S2, the scanning speed of the femtosecond laser is 0.5 - 3 m / min.

3. A femtosecond laser-based surface treatment method for orthopedic implants according to claim 1, wherein In step S2, the spot diameter of the femtosecond laser is 20 - 50 µm, and the spot pitch is 80 - 200 µm.

4. A femtosecond laser-based surface treatment method for orthopedic implants according to claim 1, characterized in that In step S2, the width of the groove is 20 - 80 µm, and the pitch is 80 - 200 µm; The hole size of the dot matrix is 20 - 80 µm, and the pitch is 50 - 100 µm; The width of the grid is 20 - 80 µm, and the pitch is 80 - 200 µm.

5. A femtosecond laser-based surface treatment method for orthopedic implants according to claim 1, characterized in that, In step S3, the spray gun power of the plasma spraying is 40 - 50 kW, the powder feeding rate is 15 - 25 g / min, and the spraying distance is 150 - 250 mm.

6. The method for surface treatment of an orthopedic implant based on femtosecond laser according to claim 1, wherein, In step S3, when the biocoating is a titanium coating, the plasma spraying is carried out under vacuum; When the biocoating is a hydroxyapatite coating, the plasma spraying is carried out in an atmospheric environment.

7. A method for surface treatment of orthopedic implants based on femtosecond laser according to claim 1, characterized in that, In step S3, when the biocoating is a titanium coating, the thickness of the coating is 150 - 600 µm; When the biocoating is a hydroxyapatite coating, the thickness of the coating is 20 - 100 µm.

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