Metal-doped diamond-like carbon film on surface of magnesium-based material and preparation method and application of metal-doped diamond-like carbon film

Abstract

The invention discloses a metal-doped diamond-like carbon film on the surface of a magnesium-based material and a preparation method and application of the metal-doped diamond-like carbon film. The preparation method of the metal-doped diamond-like carbon film on the surface of the magnesium-based material comprises the following steps that (1) the magnesium-based material is selected and subjected to forming treatment; (2) carrying out surface pretreatment on the magnesium matrix material; and (3) preparation of the metal-doped diamond-like carbon film: a pulse arc source and plasma immersion ion implantation composite technology is adopted, and the prepared metal-doped, especially copper-doped diamond-like carbon film reduces the corrosion rate of a magnesium-based material in simulated body fluid by more than one order of magnitude; the binding force, antibacterial property and corrosion resistance are comprehensively superior to those of unmodified and conventional diamond-like coatings, and reliable guarantee is provided for safe and long-acting application of the degradable magnesium alloy in the medical fields of orthopedic implantation, cardiovascular stents and the like and in severe service environments of aerospace, ocean engineering and the like.

Description

Technical Field

[0001] This invention belongs to the field of surface coating / film technology, specifically relating to a metal-doped diamond-like thin film on the surface of a magnesium-based material, its preparation method, and its application. Background Technology

[0002] Loss of tissue or organ function due to disease, trauma, and population aging is one of the major clinical challenges facing the world today. Compared with traditional medical stainless steel, titanium, and other metal materials, magnesium-based metal materials are a new generation of biodegradable implant materials. They have two core advantages: firstly, they can degrade spontaneously in the human body environment, eliminating the need for secondary surgery after tissue healing; secondly, their elastic modulus is closer to that of human bone, effectively reducing the "stress shielding" effect. Therefore, magnesium-based metal materials have broad application prospects in orthopedics, oral and maxillofacial surgery, endovascular treatment, and the digestive system. Against the backdrop of global advocacy for green, energy-saving, and sustainable development, magnesium-based metal materials, as one of the most promising metal materials of the 21st century, are also widely used in aerospace, marine environments, and new energy vehicles. However, magnesium-based metal materials often exhibit poor corrosion resistance during service, making it difficult to meet long-term usage requirements. Surface coating / film modification is an effective way to solve this problem; that is, by preparing appropriate coatings / films on their surfaces, the corrosion rate can be effectively slowed down, and corrosion resistance improved.

[0003] Diamond-like carbon (DLC) films have the characteristics of high hardness, low coefficient of friction, excellent chemical stability and good biocompatibility, making them an ideal candidate for corrosion protection of magnesium-based materials. However, the bonding force between DLC films and magnesium-based metal materials is often insufficient, and they are prone to peeling and failure under complex service environments, which seriously affects their long-term performance and is an important scientific and technological problem that needs to be solved. The main reasons for the poor bonding force are as follows: (1) Large difference in thermal expansion coefficient: The thermal expansion coefficient of magnesium metal is much higher than that of DLC films. Temperature changes during film deposition will generate significant thermal stress, leading to interface peeling; (2) High residual internal stress of DLC films: DLC films (especially with high sp³ content) usually have high compressive residual stress, while magnesium has low yield strength, making it difficult to effectively release these stresses through plastic deformation of the matrix, which can easily cause the film to crack or peel off; (3) Lack of effective interface reaction layer: DLC is a carbon-based amorphous / nanocrystalline structure with strong chemical inertness, making it difficult to form a stable chemical bond with magnesium. Magnesium carbide phase is thermodynamically unstable, magnesium and carbon have extremely low miscibility, and the diffusion coefficient of carbon in magnesium is almost zero, making it difficult to form a metallurgical bond. Therefore, the interface between the two mainly relies on physical adsorption and mechanical interlocking, and the bonding strength is inherently insufficient. (4) Mismatch in mechanical properties: Magnesium-based materials have low hardness and high toughness, while DLC films have extremely high hardness. The magnesium matrix is ​​relatively soft and cannot provide sufficient mechanical support. It is prone to plastic deformation during film deposition or under external load, leading to stress concentration and causing film cracking or peeling.

[0004] Furthermore, while traditional DLC films possess good biocompatibility, they lack inherent antibacterial activity and are unable to effectively inhibit bacterial adhesion and biofilm formation, thus failing to adequately protect against the risk of bacterial infection after implantation. Doping DLC ​​films with antibacterial metal ions can significantly impart antibacterial properties. Common antibacterial ions include copper (Cu), silver (Ag), and zinc (Zn) ions. Among these, Cu ions have attracted considerable attention due to their rapid and efficient bactericidal action, broad-spectrum antibacterial activity, and good biosafety.

[0005] The traditional method for introducing antibacterial metal ions into DLC films involves a step-by-step process: first, a DLC film is prepared on the surface of a metal material, and then antibacterial metal ions are implanted into the DLC film using ion implantation. This process has significant technical bottlenecks. The implantation depth of metal ions is typically only around tens of nanometers, existing only in the shallow surface layer of the DLC film and failing to cover the full thickness range. This method also struggles to achieve a uniform distribution of antibacterial metal ions along the depth direction of the DLC film. In actual service, the film is subject to scratches, and metal ions are continuously released. The antibacterial metal ion-doped DLC films prepared using the above process are easily lost due to surface wear or rapid dissolution, making it difficult to achieve sustained and long-term release of antibacterial metal ions. This limits the durability of the antibacterial properties of antibacterial metal ion-doped DLC films.

[0006] Traditional methods for preparing DLC ​​thin films mainly include magnetron sputtering, ion beam deposition, and plasma-enhanced chemical vapor deposition (PECVD). Thin films prepared using different techniques exhibit certain differences in structure and performance. However, these traditional methods all have limitations when preparing DLC ​​thin films on magnesium-based metal surfaces: magnetron sputtering has a low deposition rate, requires high surface roughness, and is prone to dopant aggregation; ion beam deposition equipment is expensive, has low deposition efficiency, and high-energy particle beam bombardment can cause surface damage to the magnesium substrate; PECVD has a slow deposition rate and poor adhesion between the film and the substrate. Currently, there is still a lack of an effective method for directly preparing DLC ​​thin films with strong adhesion, uniform density, and excellent corrosion protection and antibacterial properties on magnesium substrate surfaces. Summary of the Invention

[0007] The purpose of this invention is to provide a metal-doped diamond-like thin film on the surface of a magnesium-based material and its preparation method.

[0008] Another objective of this invention is to provide the application of the aforementioned magnesium-based material surface metal-doped diamond-like thin film in the preparation of corrosion-protective materials or antibacterial materials.

[0009] The first objective of this invention can be achieved by the following technical solution: a method for preparing a metal-doped diamond-like thin film on the surface of a magnesium-based material, comprising the following steps:

[0010] (1) Select magnesium matrix material and perform molding treatment;

[0011] (2) Pre-treat the surface of the magnesium matrix material;

[0012] (3) Preparation of metal-doped diamond-like carbon thin films:

[0013] After surface pretreatment, the magnesium matrix material is placed on the sample stage in the plasma immersion ion implantation PIII equipment chamber. The chamber is evacuated to the required basic vacuum, and then hydrocarbon gas is introduced to adjust the gas pressure in the vacuum chamber.

[0014] The metal target is installed at the pulsed arc source, and the voltage, frequency and pulse width of the pulsed arc source power supply are set so that the high-energy arc discharge generates a stable metal plasma. At the same time, the high-energy arc is used to ionize hydrocarbon-containing gas to generate a stable hydrocarbon-containing gas plasma.

[0015] Turn on the high-voltage pulse power supply of the plasma immersion ion implantation PIII device and synchronize its output voltage frequency with the output voltage frequency of the pulse arc source power supply. Set the pulse width, voltage and working time of the high-voltage pulse power supply to prepare a metal-doped diamond-like film on the surface of a magnesium-based material.

[0016] In the above-mentioned method for preparing metal-doped diamond-like carbon thin films on the surface of magnesium-based materials:

[0017] Preferably, the magnesium matrix material in step (1) is pure magnesium, magnesium alloy, magnesium-containing porous material, magnesium alloy-containing porous material, material after magnesium surface treatment, material after magnesium alloy surface treatment, material after magnesium porous material surface treatment, or material after magnesium alloy porous material surface treatment.

[0018] Preferably, the molding process in step (1) includes extruding the magnesium matrix material into magnesium sheets or rods, and processing them into the desired structure and shape as needed.

[0019] More preferably, the magnesium matrix material in step (1) is pure magnesium or a magnesium alloy.

[0020] Preferably, the surface pretreatment in step (2) includes grinding the magnesium matrix material to remove surface oxides and impurities, and then cleaning and drying.

[0021] Preferably, in step (3), the gas pressure in the chamber is evacuated to 1 × 10⁻⁶. -3 ~8×10 -3 Pa, then introduce 5~80 sccm of hydrocarbon-containing gas to adjust the pressure in the vacuum chamber to 1×10⁻⁶ .... -1 ~8×10 -1 Pa.

[0022] Preferably, the hydrocarbon-containing gas in step (3) is acetylene (C2H2), propyne (C3H4), butyne (C4H6), ethylene (C2H4), propylene (C3H6), butene (C4H8), methane (CH4), ethane (C2H6), propane (C3H8), or butane (C4H2). 10 Cyclohexane C6H 12One or more of benzene (C6H6), toluene (C7H8) and their derivatives.

[0023] Furthermore, hydrogen may or may not be mixed into the hydrocarbon gas mentioned in step (3).

[0024] Preferably, the metal target material in step (3) is one or more of Cu, Zn and Ag.

[0025] Preferably, in step (3), the voltage of the pulsed arc source is set to 6~15 kV, the frequency to 2~15 Hz, and the pulse width to 100~2000us, so that the high-energy arc discharge generates a stable metal plasma, and at the same time, the high-energy arc ionizes the hydrocarbon-containing gas near the pulsed arc source to generate a stable hydrocarbon-containing gas plasma.

[0026] Preferably, in step (3), the pulse width of the high-voltage pulse power supply is set to 50~700 μs, the voltage is -12~-50 kV, and the working time is 0.5~15 hours.

[0027] The copper-doped diamond-like thin film on the surface of the magnesium-based material described in this invention is mainly formed by the deposition of metal plasma and hydrocarbon-containing gas plasma on the surface of the magnesium-based material, with an amorphous carbon matrix as the substrate, and a thin film in which metal particles or clusters are embedded.

[0028] This invention employs a combined pulsed arc source and plasma immersion ion implantation technology to achieve simultaneous doping of DLC thin films and metal ions. Through a one-step process, co-deposition of DLC thin films and metal ions is achieved, effectively ensuring the uniform distribution of antibacterial metal ions within the DLC thin film. The doping amount of metal ions in the DLC thin film can be flexibly adjusted by regulating parameters such as the voltage of the pulsed arc source and plasma immersion ion implantation technology, achieving controllable doping. As long as the DLC thin film exists, its antibacterial effect will be maintained, avoiding the decline in antibacterial performance caused by film wear or excessively rapid dissolution of metal ions in traditional processes. This ensures the sustained and stable release of antibacterial ions from the DLC thin film.

[0029] The present invention also provides a metal-doped diamond-like thin film on the surface of a magnesium-based material prepared by the above method.

[0030] The first objective of the present invention can be achieved by the following technical solution: the application of the above-mentioned magnesium-based material surface metal-doped diamond-like thin film in the preparation of corrosion protection materials or antibacterial materials.

[0031] Compared with the prior art, the present invention has the following advantages:

[0032] (1) The present invention uses pulsed arc source and plasma immersion ion implantation composite technology to achieve uniform doping of metal elements and simultaneous deposition of high-quality DLC thin films. The prepared metal-doped, especially Cu-doped DLC thin films have strong bonding, dense structure and low residual stress.

[0033] (2) This invention enables DLC films to obtain excellent long-lasting broad-spectrum antibacterial properties (the inhibition rate against Staphylococcus aureus and Escherichia coli is higher than 99.9%) by controlling the doping and continuous release of metal elements, especially Cu elements. While maintaining the original high hardness, low friction and good biocompatibility of DLC, it significantly improves the anti-infection ability of magnesium-based materials and breaks through the limitation of the single function of traditional DLC films.

[0034] (3) Compared with the prior art, the metal-doped, especially Cu-doped DLC protective film prepared by the present invention reduces the corrosion rate of magnesium-based materials in simulated body fluid by more than one order of magnitude. Its bonding strength, antibacterial properties and corrosion resistance are superior to those of unmodified and conventional DLC films. It provides a reliable guarantee for the safe and long-term use of biodegradable magnesium alloys in medical fields such as orthopedic implants and cardiovascular stents, as well as in harsh service environments such as aerospace and marine engineering.

[0035] (4) The preparation method of the present invention is stable and can be mass-produced, and has significant economic and social benefits. Attached Figure Description

[0036] The present invention will now be further described with reference to the accompanying drawings and embodiments.

[0037] Figure 1 The equipment used to prepare metal-doped diamond-like carbon films on the surface of magnesium-based materials in Examples 1-9;

[0038] Figure 2 The images show the surface morphology of the samples prepared in Example 1 under a scanning electron microscope. Figure (a) shows the surface morphology of the magnesium-based material (Mg), and Figure (b) shows the surface morphology of the copper-doped DCL film-modified magnesium (Cu-DLC).

[0039] Figure 3 The energy spectrum elemental distribution diagram (a) and Raman spectrum (b) of the sample prepared in Example 1 are shown. In Figure (b), the horizontal axis represents the Raman shift and the vertical axis represents the intensity of the Raman scattered light.

[0040] Figure 4 The graph shows the bonding strength test results of the sample prepared in Example 1;

[0041] Figure 5Figure 1 shows the electrochemical test results of the samples prepared in Example 1 and Comparative Example 1 in simulated body fluid at 37°C. Figure 1(a) shows the polarization curves of magnesium-based material (Mg), undoped DCL film modified magnesium (DLC), and copper-doped DCL film modified magnesium (Cu-DLC) samples. Figure 1(b) shows the Nyquist plots of the three samples. The horizontal axis of Figure 1(a) is the current density, and the vertical axis is the electrode potential.

[0042] Figure 6 The images show the surface morphology of the samples prepared in Example 1 after immersion in simulated body fluid at 37°C for 30 days under a scanning electron microscope. Figure (a) shows the surface morphology of the magnesium-based material (Mg) sample after immersion for 30 days, and Figure (b) shows the surface morphology of the copper-doped DCL film-modified magnesium (Cu-DLC) sample after immersion for 30 days.

[0043] Figure 7 The hydrogen evolution rate and weight loss of the samples prepared in Example 1 after immersion in simulated body fluid at 37°C for 30 days are shown in Figure (a). Figure (a) shows the hydrogen evolution rate of magnesium-based material (Mg) and copper-doped DCL film modified magnesium (Cu-DLC) samples. The horizontal axis of Figure (a) is the immersion time and the vertical axis is the hydrogen evolution rate. Figure (b) shows the weight loss of the two samples. The horizontal axis of Figure (b) is the immersion time and the vertical axis is the weight loss.

[0044] Figure 8 Figure 1 shows the antibacterial rates of the samples prepared in Example 1 against Staphylococcus aureus and Escherichia coli. Figure 1(a) shows the antibacterial rates of magnesium-based material (Mg) and copper-doped DCL film modified magnesium (Cu-DLC) samples against Staphylococcus aureus, and Figure 1(b) shows the antibacterial rates of the two samples against Escherichia coli. The horizontal axis of Figure 1(a) and Figure 1(b) represents the sample name, and the vertical axis represents the antibacterial rate. Detailed Implementation

[0045] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0046] Unless otherwise specified in the following implementation plan, the test conditions are generally as per standard test conditions or the test conditions recommended by the reagent company. Unless otherwise specified, all materials and reagents used are commercially available.

[0047] Unless otherwise specified, the terms used in the following implementation methods and embodiments generally have the meanings commonly understood by those skilled in the art.

[0048] Part 1: Copper-doped diamond-like thin films on magnesium-based materials and their preparation methods

[0049] Example 1

[0050] The method for preparing copper-doped diamond-like carbon (DLC) films on magnesium-based materials provided in this embodiment includes the following steps:

[0051] (1) Select pure magnesium as the matrix material, extrude it into magnesium plates or rods, and process it into characteristic structures and shapes;

[0052] (2) Material surface pretreatment;

[0053] The pure magnesium sheet was cut into blocks of 10mm×10mm×5mm in size, and then sanded sequentially under running water using 500#, 1000#, 2000# and 3000# sandpaper. After that, it was ultrasonically cleaned with anhydrous ethanol and dried for later use.

[0054] (3) Preparation of copper-doped diamond-like thin films;

[0055] First, such as Figure 1 As shown, the pretreated pure magnesium sample was loaded into the chamber of the PIII device, and the gas pressure inside the chamber was evacuated to 3 × 10⁻⁶. -3 Pa, then 20 sccm of C2H2 gas was introduced to adjust the pressure in the vacuum chamber to 3 × 10 Pa. -1 Pa;

[0056] Secondly, the voltage of the pulsed arc source is set to 12kV, the frequency to 6Hz, and the pulse width to 800us, so that the high-energy arc discharge can generate stable Cu plasma. At the same time, the high-energy arc is used to ionize C2H2 gas to generate stable C2H2 plasma.

[0057] Finally, the high-voltage pulse power supply of PIII was turned on, and its output pulse voltage frequency was synchronized with the pulse voltage frequency output by the pulse arc source power supply. The pulse width of the high-voltage pulse power supply was set to 400 μs, and the voltage was boosted to -15 kV. After working for 5 hours, Cu-doped DLC films were prepared on the pure magnesium surface.

[0058] Example 2

[0059] The method for preparing copper-doped diamond-like carbon (DLC) films on magnesium-based materials provided in this embodiment includes the following steps:

[0060] (1) Select AZ31B magnesium alloy as the matrix material, extrude it into magnesium alloy plates or bars, and process it into characteristic structures and shapes;

[0061] (2) Material surface pretreatment;

[0062] The AZ31B magnesium alloy sheet was cut into blocks of 10mm×10mm×5mm size, and then polished in sequence under running water using 500#, 1000#, 2000# and 3000# sandpaper. After that, it was ultrasonically cleaned with anhydrous ethanol and dried for later use.

[0063] (3) Preparation of copper-doped diamond-like thin films;

[0064] First, such as Figure 1 As shown, the pretreated AZ31B magnesium alloy sample was loaded into the chamber of the PIII device, and the gas pressure inside the chamber was evacuated to 3 × 10⁻⁶. -3 Pa, then 20 sccm of C2H2 gas was introduced to adjust the pressure in the vacuum chamber to 3 × 10 Pa. -1 Pa;

[0065] Secondly, the voltage of the pulsed arc power supply is set to 12kV, the frequency to 6Hz, and the pulse width to 800us, so that the high-energy arc discharge can generate stable Cu plasma. At the same time, the high-energy arc is used to ionize C2H2 gas to generate stable C2H2 plasma.

[0066] Finally, the high-voltage pulse power supply of PIII was turned on, and its output pulse voltage frequency was synchronized with the pulse voltage frequency output by the pulse arc source power supply. The pulse width was set to 400us, the voltage was boosted to -15kV, and the working time was 5 hours. Cu-doped DLC films were then prepared on the surface of AZ31B magnesium alloy.

[0067] Example 3

[0068] The method for preparing copper-doped diamond-like carbon (DLC) films on magnesium-based materials provided in this embodiment includes the following steps:

[0069] (1) Select pure magnesium as the matrix material, extrude it into magnesium plates or rods, and process it into characteristic structures and shapes;

[0070] (2) Material surface pretreatment;

[0071] The pure magnesium sheet was cut into blocks of 10mm×10mm×5mm size, and then sanded in sequence with 500#, 1000#, 2000# and 3000# sandpaper under running water. After that, it was ultrasonically cleaned with anhydrous ethanol and dried for later use.

[0072] (3) Preparation of copper-doped diamond-like thin films;

[0073] First, such as Figure 1 As shown, the pretreated pure magnesium sample was loaded into the chamber of the PIII device, and the gas pressure inside the chamber was evacuated to 7 × 10⁻⁶. -3Pa, then 60 sccm of C2H4 gas was introduced to adjust the pressure in the vacuum chamber to 6 × 10 Pa. -1 Pa;

[0074] Secondly, the voltage of the pulsed arc power supply is set to 12kV, the frequency to 6Hz, and the pulse width to 800us, so that the high-energy arc discharge can generate stable Cu plasma. At the same time, the high-energy arc is used to ionize C2H4 gas to generate stable C2H4 plasma.

[0075] Finally, the high-voltage pulse power supply of PIII was turned on, and its output pulse voltage frequency was synchronized with the pulse voltage frequency output by the pulse arc source power supply. The pulse width was set to 400us, the voltage was boosted to -15kV, and the working time was 5 hours. Cu-doped DLC films were then prepared on the pure magnesium surface.

[0076] Example 4

[0077] The method for preparing copper-doped diamond-like carbon (DLC) films on magnesium-based materials provided in this embodiment includes the following steps:

[0078] (1) Select pure magnesium as the matrix material, extrude it into magnesium plates or rods, and process it into characteristic structures and shapes;

[0079] (2) Material surface pretreatment;

[0080] The pure magnesium sheet was cut into blocks of 10mm×10mm×5mm size, and then sanded in sequence with 500#, 1000#, 2000# and 3000# sandpaper under running water. After that, it was ultrasonically cleaned with anhydrous ethanol and dried for later use.

[0081] (3) Preparation of copper-doped diamond-like thin films;

[0082] First, such as Figure 1 As shown, the pretreated pure magnesium sample was loaded into the chamber of the PIII device, and the gas pressure inside the chamber was evacuated to 3 × 10⁻⁶. -3 Pa, then 20 sccm of C2H2 gas was introduced to adjust the pressure in the vacuum chamber to 3 × 10 Pa. - 1 Pa;

[0083] Secondly, the voltage of the pulsed arc power supply is set to 7kV, the frequency to 12Hz, and the pulse width to 400us, so that the high-energy arc discharge can generate stable Cu plasma. At the same time, the high-energy arc is used to ionize C2H2 gas to generate stable C2H2 plasma.

[0084] Finally, the high-voltage pulse power supply of PIII was turned on, and its output pulse voltage frequency was synchronized with the pulse voltage frequency output by the pulse arc source power supply. The pulse width was set to 400us, the voltage was boosted to -15kV, and the working time was 10 hours. Cu-doped DLC films were then prepared on pure magnesium surfaces.

[0085] Example 5

[0086] The method for preparing copper-doped diamond-like carbon (DLC) films on magnesium-based materials provided in this embodiment includes the following steps:

[0087] (1) Select pure magnesium as the matrix material, extrude it into magnesium plates or rods, and process it into characteristic structures and shapes;

[0088] (2) Material surface pretreatment;

[0089] The pure magnesium sheet was cut into blocks of 10mm×10mm×5mm size, and then sanded in sequence with 500#, 1000#, 2000# and 3000# sandpaper under running water. After that, it was ultrasonically cleaned with anhydrous ethanol and dried for later use.

[0090] (3) Preparation of copper-doped diamond-like thin films;

[0091] First, such as Figure 1 As shown, the pretreated pure magnesium sample was loaded into the chamber of the PIII device, and the gas pressure inside the chamber was evacuated to 3 × 10⁻⁶. -3 Pa, then 20 sccm of C2H2 gas was introduced to adjust the pressure in the vacuum chamber to 3 × 10 Pa. -1 Pa;

[0092] Secondly, the voltage of the pulsed arc power supply is set to 12kV, the frequency to 6Hz, and the pulse width to 800us, so that the high-energy arc discharge can generate stable Cu plasma. At the same time, the high-energy arc is used to ionize C2H2 gas to generate stable C2H2 plasma.

[0093] Finally, the high-voltage pulse power supply of PIII was turned on, and its output pulse voltage frequency was synchronized with the pulse voltage frequency output by the pulse arc source power supply. The pulse width was set to 150 μs, the voltage was boosted to -30 kV, and the working time was 2 hours. Cu-doped DLC films were then prepared on the pure magnesium surface.

[0094] Example 6

[0095] The difference from Example 1 is that the metal used is zinc (Zn).

[0096] Example 7

[0097] The difference from Example 1 is that the metal used is silver (Ag).

[0098] Example 8

[0099] The difference from Example 1 is that the hydrocarbon gas used is methane (CH4).

[0100] Example 9

[0101] The difference from Example 1 is that the hydrocarbon gas used is propylene (C3H6).

[0102] Comparative Example 1

[0103] The difference between Comparative Example 1 and Example 1 is that:

[0104] In step (3), the pulsed arc source is not turned on, Cu doping is not performed, and a traditional 100W power RF power supply is used to ionize C2H2 gas to obtain an undoped DLC film on a pure magnesium surface.

[0105] Part Two: Performance Testing

[0106] Example 1 was selected as a representative example, and scanning electron microscopy, energy dispersive spectroscopy, elemental and Raman spectroscopy, adhesion testing, electrochemical testing, immersion testing, hydrogen evolution testing, weight loss testing, and antibacterial testing were performed on the sample, either alone or with a magnesium substrate sample without a thin film. The results are as follows: Figures 2 to 8 As shown.

[0107] Figure 2 The pure magnesium (Mg) obtained in Example 1 ( Figure 2 (a) and scanning electron microscope images of the surface morphology of copper-doped diamond-like carbon (Cu-DLC) films. Figure 2 (b)).

[0108] like Figure 2As shown in (b), the Cu-DLC film is uniformly covered on the surface of the pure magnesium substrate. It is dense and uniform and no obvious defects were observed. This is mainly attributed to the non-line-of-sight processing and high ionization rate during the preparation process. The detailed explanation is as follows: (1) During the pulse bias, the entire workpiece (cathode) is wrapped by the plasma sheath, and ions are accelerated vertically from all directions to bombard the workpiece surface. This means that uniform ion implantation and film deposition can be achieved for workpieces with complex shapes, grooves, internal holes or threads without the need for workpiece rotation. Since it is a non-line-of-sight, integral process, the workpieces can be tightly stacked and the loading capacity is large, which is particularly suitable for batch processing of small parts. In contrast, radio frequency discharge is essentially a "line-of-sight" process. Ions mainly move along the direction of the electric field lines, and the uniformity of the film deposited in different parts is relatively poor. For complex workpieces, complex fixtures and rotation systems are required to ensure uniformity, and deep holes and grooves are difficult to be effectively processed. (2) The extremely high pulse voltage can generate high-density plasma, and the proportion of ions in the plasma is high. The continuous bombardment of high-energy ions has sputtering and recoil injection effects during deposition, resulting in dense, stress-free (or stress-tunable) diamond-like carbon films with higher sp3 bond content. In contrast, the plasma density and ionization rate in the radio frequency discharge process depend on the radio frequency power, but the ion energy is usually lower; the deposition process is mainly physical vapor deposition, and the film density and sp3 content are usually lower than those of the high-energy ion-assisted PIII process.

[0109] Figure 3 The image shows the energy dispersive spectroscopy (EDS) elemental distribution and Raman spectrum of the Cu-DLC thin film obtained in Example 1.

[0110] Figure 3 (a) shows that the DLC film contains C and Cu elements, and the two elements are uniformly distributed in the film. For example... Figure 3 As shown in (b), the black curve is the original test spectrum, the red curve is the superimposed spectrum after Gaussian function peak fitting, and the blue and green curves correspond to the fitted D and G peaks, respectively. Cu-doped DLC films at 1355 cm⁻¹... -1 and 1535 cm -1 Typical D and G peaks appear at this location. The G peak shows a significant low-frequency shift (1535 cm). -1 The high AD / AG value (~1.80) and the large amount of sp2 carbon in the film indicate that the sp2 carbon mainly exists in the form of nanoscale clusters, and the sp3 carbon content is relatively high. The maximum full width at half maximum (FWHM) of the D peak (~368.8 cm⁻¹) -1 This further confirms the high degree of disorder in the structure, which may originate from the non-equilibrium deposition characteristics of the PIII process and the interface defects introduced by copper doping. In summary, this film exhibits a high sp3 content and high disorder DLC structure, and copper doping may have further enhanced the structural disorder through interface effects.

[0111] Figure 4The image shows the test results of the adhesion between the Cu-DLC film obtained in Example 1 and the substrate.

[0112] like Figure 4 As shown, the Cu-DLC film prepared in Example 1 was tested for adhesion to the substrate by the cross-cut test. The film edges were smooth and flat after the scratch test, and no peeling was observed. The test grid remained intact. According to the ASTM-D 3359 standard, the adhesion level between the film and the substrate was the highest, 5B, indicating that the adhesion performance between the two is excellent. The Cu-doped DLC film exhibits good adhesion to magnesium-based materials, which is mainly attributed to the advantages of advanced preparation technology and copper doping, as follows: (1) A high-voltage pulse power supply is used, the core advantage of which is that it can apply a negative high-voltage pulse bias of several kilovolts to tens of thousands of volts to the workpiece. This allows carbon ions (such as C) in the plasma to be biased. + ) can obtain extremely high kinetic energy and be directly injected into the substrate below the surface (several to tens of nanometers) to form a "hybrid interface layer" composed of the mutual diffusion of injected ions and substrate elements. This greatly improves the adhesion between the DLC film and the substrate. Radio frequency discharge technology mainly relies on bias voltage (usually several hundred to one thousand volts) to attract ions. The ion energy is relatively low, and the interface formed is mainly based on physical / chemical adsorption and shallow diffusion. The adhesion is usually weaker than that of the PIII method. (2) Cu doping can significantly improve the bonding force between DLC film and magnesium-based metal materials. This is mainly due to the fact that Cu doping can relax the carbon bond distortion in the DLC network, directly reduce the inherent high residual stress of the film, and reduce the driving force for the film to fall off the substrate.

[0113] Figure 5 The graph shows the electrochemical test results of the Mg, Cu-DLC obtained in Example 1 and the DLC sample in Comparative Example 1 in simulated body fluid at 37°C.

[0114] To evaluate corrosion resistance, the Cu-DLC thin film sample prepared in Example 1 and the bare Mg substrate sample were immersed in an artificial simulated body fluid at 37°C for polarization curve testing. The results are as follows: Figure 5 As shown in (a), the corrosion potential of the bare Mg matrix is ​​-1.76 V vs. SCE, and the corrosion current density is 3.3 × 10⁻⁶ V. -5 A / cm 2 This indicates a high tendency and rapid corrosion rate in simulated body fluids, mainly attributed to the high electrochemical activity of magnesium. The corrosion potential of the DLC thin film sample shifted positively, while the corrosion current density decreased slightly to 1.8 × 10⁻⁶. -5 A / cm 2 This indicates that the DLC film alone offers limited protection against corrosion of the magnesium substrate. In contrast, the corrosion potential of the Cu-DLC film sample shifted positively to -1.50 V vs. SCE, and the corrosion current density decreased to 3.2 × 10⁻⁶.- 6 A / cm 2 The degradation rate was nearly an order of magnitude. The results indicate that the Cu-DLC film significantly inhibited the degradation of the Mg substrate, providing excellent corrosion protection. Figure 5 The Nyquist plot in (b) reflects the impedance characteristics of the sample in simulated body fluid. The size of the capacitance arc directly reflects the corrosion resistance of the material; that is, the larger the capacitance arc, the better the corrosion resistance. It can be seen that the capacitance arc radius of the Cu-DLC film sample is significantly larger than that of the pure magnesium and DLC film samples, indicating that the Cu-DLC film can effectively delay the corrosion and degradation process of the magnesium substrate.

[0115] Figure 6 The image shows the surface morphology of the Mg and Cu-DLC samples obtained in Example 1 after immersion in simulated body fluid at 37°C for 30 days under a scanning electron microscope.

[0116] like Figure 6 As shown in (a), after immersion for 30 days, numerous cracks and obvious corrosion products appeared on the surface of the unmodified Mg matrix, indicating that it underwent severe corrosion and degradation in the simulated physiological environment. In contrast, as Figure 6 As shown in (b), the surface structure of the Cu-DLC thin film sample remained intact, with no obvious cracks or peeling. Only a small amount of corrosion products were observed, indicating that the corrosion process was significantly delayed.

[0117] Figure 7 The hydrogen evolution results and weight loss rate of the Mg and Cu-DLC samples obtained in Example 1 after immersion in simulated body fluid at 37°C for 30 days are shown.

[0118] like Figure 7 As shown in (a), the hydrogen evolution rate of the Cu-DLC sample is lower than that of the Mg sample, indicating that the Cu-DLC film can effectively improve the hydrogen evolution resistance of the magnesium substrate. Figure 7 The weight loss results in (b) show that after 30 days of immersion, the Mg substrate lost 15% of its weight, while the Cu-DLC film sample lost only 8%. This data further confirms that the Cu-DLC film can effectively slow down the corrosion rate of the magnesium substrate and significantly improve its long-term corrosion resistance.

[0119] Figure 8 The graph shows the antibacterial rates of the Mg and Cu-DLC samples obtained in Example 1 against Staphylococcus aureus and Escherichia coli.

[0120] like Figure 8 As shown, the Mg matrix sample is effective against Staphylococcus aureus (Staphylococcus aureus). Figure 8 (a) Figure) and Escherichia coli ( Figure 8(b) Figure 1) It has certain antibacterial properties, with an antibacterial rate of approximately 84%. The Mg matrix releases Mg during contact with bacteria. 2+ This causes a local pH increase accompanied by hydrogen evolution; this can lead to an increase in the bacterial outer membrane potential, increasing membrane permeability, and simultaneously inducing the production of reactive oxygen species (ROS), triggering bacterial oxidative stress, thereby inhibiting their growth and reproduction. In contrast, the Cu-DLC film sample showed an antibacterial rate exceeding 99.9% against both bacteria, and its mechanism of action is mainly manifested in Cu… 2+ The release of Cu has a bactericidal effect. Cu-DLC samples can continuously and stably release Cu during co-culturing with bacteria. 2+ Cu 2+ It has strong oxidizing properties, which can destroy bacterial cell membranes, increase bacterial cell membrane permeability, and lead to bacterial death. Compared with Mg matrix samples, it has more significant antibacterial activity against bacteria.

[0121] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. A method for preparing a metal-doped diamond-like carbon film on the surface of a magnesium-based material, characterized in that, Includes the following steps: (1) Select magnesium matrix material and perform molding treatment; (2) Pre-treat the surface of the magnesium matrix material; (3) Preparation of metal-doped diamond-like carbon thin films: After surface pretreatment, the magnesium matrix material is placed on the sample stage in the plasma immersion ion implantation PIII equipment chamber. The chamber is evacuated to the required basic vacuum, and then hydrocarbon gas is introduced to adjust the gas pressure in the vacuum chamber. The metal target is installed at the pulsed arc source, and the voltage, frequency and pulse width of the pulsed arc source power supply are set so that the high-energy arc discharge generates a stable metal plasma. At the same time, the high-energy arc is used to ionize hydrocarbon-containing gas to generate a stable hydrocarbon-containing gas plasma. Turn on the high-voltage pulse power supply of the plasma immersion ion implantation PIII device and synchronize its output voltage frequency with the output voltage frequency of the pulse arc source power supply. Set the pulse width, voltage and working time of the high-voltage pulse power supply to prepare a metal-doped diamond-like film on the surface of a magnesium-based material.

2. The method for preparing a metal-doped diamond-like carbon film on the surface of a magnesium-based material according to claim 1, characterized in that, The magnesium matrix material mentioned in step (1) is pure magnesium, magnesium alloy, magnesium-containing porous material, magnesium alloy-containing porous material, material after magnesium surface treatment, material after magnesium alloy surface treatment, material after magnesium porous material surface treatment, or material after magnesium alloy porous material surface treatment.

3. The method for preparing a metal-doped diamond-like carbon film on the surface of a magnesium-based material according to claim 1, characterized in that, The surface pretreatment described in step (2) includes grinding the magnesium matrix material to remove surface oxides and impurities, followed by cleaning and drying.

4. The method for preparing a metal-doped diamond-like carbon film on the surface of a magnesium-based material according to claim 1, characterized in that, In step (3), the gas pressure in the chamber is evacuated to 1 × 10⁻⁶. -3 ~8×10 -3 Then, introduce 5-80 sccm of hydrocarbon gas to adjust the pressure in the vacuum chamber to 1×10⁻⁶ Pa. -1 ~8×10 -1 Pa.

5. The method for preparing a metal-doped diamond-like carbon film on the surface of a magnesium-based material according to claim 1, characterized in that, The hydrocarbon-containing gas mentioned in step (3) is acetylene (C2H2), propyne (C3H4), butyne (C4H6), ethylene (C2H4), propylene (C3H6), butene (C4H8), methane (CH4), ethane (C2H6), propane (C3H8), or butane (C4H2). 10 Cyclohexane C6H 12 One or more of benzene (C6H6), toluene (C7H8) and their derivatives.

6. The method for preparing a metal-doped diamond-like carbon film on the surface of a magnesium-based material according to claim 1, characterized in that, The metal target material mentioned in step (3) is one or more of Cu, Zn and Ag.

7. The method for preparing a metal-doped diamond-like carbon film on the surface of a magnesium-based material according to claim 1, characterized in that, In step (3), the voltage of the pulsed arc source is set to 6~15 kV, the frequency to 2~15 Hz, and the pulse width to 100~2000us, so that the high-energy arc discharge generates a stable metal plasma. At the same time, the high-energy arc ionizes the hydrocarbon-containing gas near the pulsed arc source to generate a stable hydrocarbon-containing gas plasma.

8. The method for preparing a metal-doped diamond-like carbon film on the surface of a magnesium-based material according to claim 1, characterized in that, In step (3), the pulse width of the high voltage pulse power supply is set to 50~700us, the voltage is -12~-50kV, and the working time is 0.5~15 hours.

9. A metal-doped diamond-like thin film on the surface of a magnesium-based material, characterized in that, It is prepared by the method described in any one of claims 1-8.

10. The application of the metal-doped diamond-like thin film on the surface of the magnesium-based material as described in claim 9 in the preparation of corrosion-protective materials or antibacterial materials.

Images