A method for controlling the phase of tantalum coating based on low-temperature magnetron sputtering and its application

Abstract

The present invention discloses a method for controlling the phase of tantalum coatings based on low-temperature magnetron sputtering and its application, belonging to the field of coating preparation. The above-mentioned control method includes: (1) pretreatment: high-energy bombardment of the base material; (2) controlling the phase of the tantalum coating to be the β phase: depositing a tantalum coating on the surface of the pretreated base material; (3) controlling the phase of the tantalum coating to be the α phase: first depositing a base layer on the surface of the pretreated base material, and then depositing the tantalum coating. The present invention realizes the controllable deposition of the β phase / α phase of the tantalum coating below 100°C through low-temperature magnetron sputtering technology. The β phase is obtained without a base layer, and the α phase is obtained by a pure titanium or titanium-tantalum mixed base layer. The latter improves the crystallinity of the α phase through low-energy interface control. The titanium-tantalum mixed layer can coordinate the thermal expansion difference, so that the coating maintains high bonding strength. Therefore, the present invention is suitable for sandblasting and acid-etching titanium alloy dental implants, taking into account the low-temperature process compatibility and clinical performance, and solving the problems of phase control and bonding strength.

Description

Technical Field

[0001] The present invention belongs to the field of coating preparation, and in particular relates to a method for regulating the physical phase of a tantalum coating based on low-temperature magnetron sputtering and an application thereof. Background Art

[0002] Tantalum (Ta) has shown broad application prospects in the field of biomedical implant materials due to its excellent biocompatibility, outstanding corrosion resistance, and good mechanical properties. In particular, in the field of dental implants, the introduction of tantalum coatings can significantly improve the implant's osseointegration and long-term stability, which is crucial to the success of oral implant restorations.

[0003] However, tantalum exists in two crystal structures at room temperature: the body-centered cubic β-Ta (stable phase) and the tetragonal α-Ta (metastable phase). These different phases significantly influence the mechanical properties of the coating, such as hardness and wear resistance, and thus the effectiveness of implants in clinical applications. Therefore, precisely controlling the phase composition of tantalum coatings to adapt them to diverse clinical application requirements has become a key research issue in this field.

[0004] Traditional tantalum coating preparation methods, such as high-temperature sputtering and plasma spraying, typically require high deposition temperatures (>300°C). Under such high-temperature conditions, the titanium alloy substrate is prone to thermal deformation or phase transformation, which can seriously affect its mechanical properties and dimensional stability, limiting the application of these traditional methods in temperature-sensitive precision medical devices such as dental implants.

[0005] Magnetron sputtering, as a low-temperature deposition method (<100°C), can produce tantalum coatings while avoiding thermal damage to the substrate, offering a new approach to addressing the high-temperature issues associated with traditional methods. However, there is currently a lack of systematic research on how to precisely control the tantalum phase (α or β) at low temperatures, making it difficult to produce tantalum coatings with specific phase compositions tailored to specific needs.

[0006] Furthermore, the bonding strength of tantalum coatings to the substrate directly impacts their effectiveness in dental implant applications. In practice, dental implants must withstand a variety of complex mechanical loads, particularly under high-torque implantation conditions (e.g., 60 N·cm), which place even higher demands on the bonding strength between the coating and the substrate. However, existing technologies have yet to systematically investigate the relationship between the base coat composition and the tantalum coating phase, nor have they explored its practical application performance on sandblasted and acid-etched dental implant surfaces. Ensuring high bonding strength of tantalum coatings under these high-torque implantation conditions remains a pressing technical challenge.

[0007] In summary, developing a phase control method for low-temperature magnetron sputtering tantalum coatings to achieve controllable deposition of α-phase or β-phase and applying it to the surface of dental implants treated with sandblasting and acid etching has important scientific significance and clinical application value for solving the problems existing in the existing technology and improving the performance and clinical effects of dental implants. Summary of the Invention

[0008] Purpose of the invention: In order to solve the defects in the prior art that the physical phase of tantalum coating is difficult to accurately control and the bonding strength between the coating and the substrate is insufficient, the first purpose of the present invention is to provide a method for controlling the physical phase of tantalum coating based on low-temperature magnetron sputtering. The second purpose of the present invention is to provide an application of the above-mentioned control method.

[0009] Technical solution: The method for controlling the phase of tantalum coating based on low-temperature magnetron sputtering described in the present invention adopts low-temperature magnetron sputtering technology and includes the following steps:

[0010] (1) Pretreatment: high-energy bombardment of the substrate material;

[0011] (2) Controlling the tantalum coating phase to be β phase: depositing a tantalum coating on the surface of the pretreated substrate;

[0012] (3) Regulating the tantalum coating phase to be α phase: first deposit a base layer on the surface of the pretreated substrate material, and then deposit the elemental tantalum coating.

[0013] Furthermore, in step (1), the matrix material is selected from one of 316L stainless steel, titanium alloy or silicon wafer, wherein the titanium alloy matrix (such as Ti-6Al-4V) has excellent biocompatibility and mechanical properties, and is particularly suitable for application scenarios such as dental implants that have strict requirements on material biosafety and mechanical stability; 316L stainless steel has wide application potential in the field of industrial wear-resistant coatings due to its excellent corrosion resistance; silicon wafer matrix is ​​often used as a thin film matrix research, which can provide a highly controllable surface environment for coating deposition, and combined with characterization techniques such as X-ray diffraction (XRD) and scanning electron microscopy (SEM), it can achieve high-precision analysis of the coating crystal structure, phase composition and micromorphology.

[0014] Furthermore, in step (1), the process parameters of the high-energy bombardment are: using argon ions for high-energy bombardment, the flow rate is 30 sccm to 60 sccm, the chamber pressure is 0.1 Pa to 0.4 Pa, the substrate negative bias is 200 V to 800 V, the tantalum target current is 0.1 A to 1 A, and the time is 20 to 40 min. The argon ion flow rate and deposition gas pressure work together to control the bombardment ion density. A flow rate of 30 sccm and a gas pressure of 0.1 Pa correspond to a low ion density, which is suitable for gentle cleaning of sensitive substrates such as silicon wafers. A flow rate of 60 sccm and a gas pressure of 0.4 Pa form a high-density ion flow, which can effectively remove the surface oxide layer (such as TiO2) and contaminants of titanium alloys. The substrate negative bias voltage of 200V to 800V regulates the ion bombardment energy. Low bias voltage (200V to 400V) achieves surface activation without damaging the substrate, and high bias voltage (600V to 800V) can form a nano-scale rough structure (roughness Ra of 0.2μm to 0.5μm) on the substrate surface, further enhancing the mechanical bite of the coating. A tantalum target current of 0.1A to 1A is used to synchronously sputter trace tantalum atoms during the bombardment stage, forming an atomic-level bonding interface on the substrate surface, which further improves the initial bonding strength of the coating.

[0015] Furthermore, in steps (2) to (3), the deposition temperature is lower than 100°C, the target-substrate distance is 10 cm to 15 cm, the substrate negative bias voltage is 30 V to 90 V, and the total thickness of the coating is 100 nm to 1000 nm. The target-substrate distance of 10 cm to 15 cm is beneficial for balancing the kinetic energy of the sputtered particles and the scattering loss.

[0016] Furthermore, in step (2) to step (3), the deposition parameters of the elemental tantalum coating are: tantalum target current is 1A to 4A, preferably 2A to 3A, and deposition time is 30min to 80min.

[0017] Furthermore, in step (3), the base layer is a single titanium metal layer or a titanium-tantalum mixed metal layer; the deposition parameters of the single titanium metal layer are: a titanium target current of 6 to 8 A, and a deposition time of 1 to 10 minutes; the deposition parameters of the titanium-tantalum mixed metal layer are: a titanium target current of 6 to 8 A, a tantalum target current gradually increasing from 0 A to 1 A to 4 A, and a deposition time of 1 to 10 minutes. The tantalum target current increases gradually from 0 A to 1 A to 4 A, so that the base layer gradually transitions from a pure titanium layer to a titanium-tantalum solid solution layer, forming a composition gradient distribution. This gradient structure can effectively reduce interfacial stress.

[0018] Application of the tantalum coating prepared by the control method of the present invention in the preparation of sandblasted and acid-etched titanium alloy dental implants.

[0019] Principle of the invention: The present invention adopts the magnetron sputtering deposition principle of interface energy regulation and lattice matching induced phase change to design a base layer structure with different compositions, thereby achieving precise control of the tantalum coating phase under low temperature environment.

[0020] The β-phase induction mechanism without a primer layer: When tantalum coatings are deposited directly on the substrate of titanium alloy dental implants, a 10.6% lattice mismatch exists between tantalum (lattice constant 0.330nm) and titanium (lattice constant 0.295nm), resulting in significantly high strain energy and high interface energy at the interface. Under this high-energy state, the body-centered cubic β-Ta phase effectively adapts to the high strain environment through lattice distortion, becoming the preferred stable phase for nucleation, ultimately forming a coating with a single β-Ta phase structure.

[0021] The α-phase induction mechanism of the pure titanium base layer: After pre-depositing a pure titanium base layer on the substrate surface, titanium atoms diffuse toward the tantalum coating during magnetron sputtering, forming a titanium-tantalum transition zone at the interface. This transition zone alters the local chemical environment, lowering the nucleation barrier for the tetragonal α-Ta phase. This lowers the nucleation barrier for the α-Ta phase compared to the β-Ta phase, leading to preferential nucleation and growth, thus enabling controlled deposition of the α-Ta coating.

[0022] The α-phase strengthening mechanism of the titanium-tantalum mixed basecoat: By preparing a mixed basecoat composed of a titanium-tantalum solid solution, its unique electron cloud distribution can control the kinetic energy of the sputtered atoms to a low energy range of 5eV to 15eV. In this low-kinetic-energy deposition environment, the formation of the thermodynamically stable β-Ta phase is suppressed. The metastable α-Ta phase, whose low-kinetic-energy atoms are more likely to retain a non-equilibrium crystal structure, dominates the nucleation stage, ultimately forming a single α-Ta phase coating that is completely opposite to the unprimed system.

[0023] Strengthening mechanism for improving the bonding strength between coating and substrate: The specific roughness and residual compressive stress field formed on the substrate surface treated by sandblasting and acid etching build a gradient stress matching system with the multilayer coating structure. Among them, the titanium-tantalum mixed base layer serves as a key stress buffer layer, which can effectively coordinate the titanium alloy substrate (thermal expansion coefficient 8.6×10 -6 / K) and tantalum coating (thermal expansion coefficient 6.5×10 -6 The difference in thermal expansion between the coating and the substrate (K) can improve the bonding strength between the coating and the substrate to a level that can withstand a high torque of 60N•cm implantation through interfacial stress buffering, significantly enhancing the long-term service stability of the dental implant.

[0024] Through the above-mentioned base coating composition design and interface control technology, the present invention realizes the controllable preparation of a single β-Ta or α-Ta phase coating according to clinical needs under low-temperature magnetron sputtering conditions below 100°C, and simultaneously solves the problem of coating peeling in high-torque implant scenarios, providing an innovative technical solution for the surface modification of biomedical implant materials such as dental implants.

[0025] Beneficial effects: Compared with the existing technology, the present invention has the following significant effects: (1) Control of base layer composition: By designing differentiated base layer structures such as no base layer, pure titanium layer or titanium-tantalum mixed layer, the controlled deposition of β phase or α phase in the tantalum coating is achieved, accurately matching the requirements of different clinical applications for the mechanical properties of the coating; (2) High torque bonding performance: The titanium-tantalum mixed base layer optimizes the interface metallurgical bonding, so that the tantalum coating still maintains excellent adhesion under a high implantation torque of 60N•cm, effectively avoiding the risk of peeling of traditional coatings; (3) Low temperature process adaptability: The magnetron sputtering technology with a deposition temperature below 100°C is used to avoid thermal deformation or phase change of the titanium alloy substrate caused by high temperature, ensuring the original mechanical properties and dimensional stability of the substrate; (4) Clinical application advantages: It is suitable for the surface of dental implants treated with sandblasting and acid etching. While improving the bone integration ability, it takes into account the mechanical properties and biocompatibility of the coating to meet the implantation needs of complex clinical scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Surface scanning electron microscope morphology images of the tantalum coatings prepared in Examples 1 to 4;

[0027] Figure 2 The cross-sectional scanning electron microscope images of the tantalum coatings prepared in Examples 1 to 4 are shown;

[0028] Figure 3 1 is a phase composition diagram of the tantalum coatings prepared in Examples 1 to 4;

[0029] Figure 4 This is an appearance diagram of the tantalum coating obtained by low-temperature magnetron sputtering on the surface of a sandblasted and acid-etched dental implant in Example 1;

[0030] Figure 5 This is a scanning electron microscope image of the tantalum coating surface obtained by low-temperature magnetron sputtering in Example 1 on the sandblasted and acid-etched dental implant surface;

[0031] Figure 6 The diagram shows the bonding force of the tantalum coatings prepared in Examples 1 to 4 when implanted at a torque of 60 N·cm. DETAILED DESCRIPTION

[0032] The present invention is further described in detail below with reference to the embodiments and accompanying drawings.

[0033] Example 1: The method for controlling the phase of a tantalum coating based on low-temperature magnetron sputtering described in this example uses low-temperature magnetron sputtering technology and includes the following steps:

[0034] (1) Preprocessing:

[0035] (11) First, a high-purity titanium target (3N, 99.9%) and a high-purity tantalum target (3N5, 99.95%) were placed opposite to each other on two magnetrons in the cavity, and the 316L stainless steel substrate, titanium alloy substrate, and silicon wafer substrate were ultrasonically cleaned in alcohol for 10 minutes and dried for use;

[0036] (12) Assemble the substrate onto the chamber fixture, adjust the chamber pressure to 0.23 Pa, the target-substrate distance to 15 cm, introduce high-purity argon gas at 40 sccm, and wait until the chamber vacuum is evacuated to 4×10 -3 Pa, the substrate surface is bombarded with high energy by high-bias sputtering argon ions to remove the oxide layer. The substrate negative bias is set to 400 V, the main alloy element target is tantalum target, the current is 0.5 A, and the time is 30 min.

[0037] (2) Regulating the tantalum coating phase to α phase:

[0038] (21) The substrate negative bias voltage was reduced to 60 V, and a titanium-tantalum mixed metal base layer was deposited on the substrate surface for 10 minutes. The titanium target current was kept constant at 6 A, and the tantalum target current was increased from 0.5 A to 3 A.

[0039] (22) Finally, a single tantalum metal layer was deposited for 40 minutes, the titanium target was turned off, the tantalum target current was kept constant at 3A, the substrate negative bias voltage was kept constant at 60V, and the deposition end temperature was lower than 100°C to obtain a 316L stainless steel substrate-titanium-tantalum mixed metal base layer-single tantalum metal layer, a titanium alloy substrate-titanium-tantalum mixed metal base layer-single tantalum metal layer, and a silicon wafer substrate-titanium-tantalum mixed metal base layer-single tantalum metal layer.

[0040] Example 2: Based on Example 1, the negative bias voltage of the titanium-tantalum mixed base layer in step (21) and the single tantalum metal layer in step (22) are both adjusted to 90V, and the other parameters remain unchanged.

[0041] Example 3: Based on Example 1, the base layer in step (21) is a single-element titanium metal base layer. At this time, the titanium target current is maintained at 6A, and the tantalum target is turned off. In addition, the substrate negative bias voltage of the single-element titanium base layer in step (21) and the single-element tantalum metal layer in step (22) is adjusted to 90V, and the other parameters remain unchanged.

[0042] Example 4: The method for controlling the phase of a tantalum coating based on low-temperature magnetron sputtering described in this embodiment adopts low-temperature magnetron sputtering technology and includes the following steps:

[0043] (1) Pretreatment is the same as in Example 1;

[0044] (2) Control the tantalum coating phase to be β phase: deposit a tantalum metal layer for 40 minutes, turn off the titanium target, keep the tantalum target current at 3A, keep the substrate negative bias at 90V, and the deposition end temperature below 100℃.

[0045] Example 5: The difference from Example 1 is that in step (22), the tantalum target current is 1A.

[0046] Example 6: The difference from Example 1 is that in step (22), the tantalum target current is 4A.

[0047] The surface and cross-sectional SEM morphologies of the coatings deposited in Examples 1 to 4 are shown in Figure 1. Figure 1 and Figure 2 The distribution of titanium and tantalum elements on its surface is shown in Table 1, and the phase composition analysis results are shown in Figure 3 As shown (the coating with silicon wafer as the substrate was used to detect the XRD phase and cross-sectional morphology and film thickness. This is because the diffraction peaks of the titanium alloy substrate and tantalum overlap and are difficult to distinguish clearly, while the diffraction peaks of the silicon substrate and tantalum are easier to distinguish). In addition, the appearance, surface scanning electron microscopy morphology and bonding strength of the tantalum coating on the sandblasted acid-etched dental implant surface made with titanium alloy as the substrate in Example 1 under the implantation torque of 60N·cm correspond to Figure 4 、 Figure 5 and Figure 6 shown.

[0048] Table 1 Surface titanium and tantalum content of the coatings obtained in Examples 1 to 4

[0049] Element / atomic percentage Example 1 Example 2 Example 3 Example 4 Ti 11.23 12.03 12.46 0 Ta 88.77 87.97 87.54 100

[0050] Through the experimental verification of Examples 1 to 4, the control method of the present invention can effectively control the phase structure of the tantalum coating and improve the interface bonding performance. The specific results are as follows:

[0051] 1. Characterization of basic coating properties

[0052] 1. Surface morphology and film thickness: The tantalum coating surfaces of Examples 1 to 4 all exhibited a dense, defect-free microstructure, such as Figure 1 As shown in Figure 2, the film thickness is controlled at about 200 nm. Figure 2 As shown, it shows that high-quality coatings with uniform morphology can be prepared under different primers and process parameters.

[0053] 2. Element content distribution As shown in Table 1, the tantalum content on the coating surface of Example 4 without a primer layer (substrate negative bias 90V) is 100 at.%, while titanium is detected on the coating surface of Examples 1 to 3 with a primer layer:

[0054] Titanium-tantalum mixed base layer (Example 1, substrate negative bias 60V): titanium content 11.23at.%, tantalum content 88.77at.%;

[0055] Titanium-tantalum mixed base layer (Example 2, substrate negative bias 90 V): titanium content 12.03 at.%, tantalum content 87.97 at.%;

[0056] Pure titanium base layer (Example 3, substrate negative bias 90 V): titanium content 12.46 at.%, tantalum content 87.54 at.%. The introduction of base layer elements leads to the presence of titanium on the coating surface, and different base layer compositions and negative bias parameters affect the element ratios.

[0057] 3. Phase structure control X-ray diffraction analysis such as Figure 3 The results show that Example 4, without a base layer, forms a single β-Ta phase structure. Both the pure titanium base layer (Example 3) and the titanium-tantalum mixed base layer (Examples 1 and 2) induce the formation of an α-Ta phase structure. Of these, Example 1 (titanium-tantalum mixed base layer, 60V) exhibits the highest α-Ta phase crystallinity and the strongest characteristic peak intensity, indicating that lower negative bias voltages can improve α-phase crystallization quality.

[0058] 2. Application performance test of sandblasting and acid etching dental implants

[0059] 1. Surface morphology optimization After the tantalum coating of Example 1 is applied to the surface of the dental implant treated by sandblasting and acid etching, the coating has a uniform appearance, such as Figure 5 As shown, SEM observations showed that the surface roughness was reduced and evenly distributed, as shown in Figure 5 As shown in Figure 3, this feature is beneficial to improving the bone integration environment of the implant.

[0060] 2. High torque bonding performance In the 60N•cm implant torque test, e.g. Figure 6 shown.

[0061] No black debris was generated around the pores of the coating in Example 1, indicating excellent interface bonding strength;

[0062] There are a small amount of black debris around the pores of the coatings of Examples 2 and 3, and the bonding strength is second to none;

[0063] In Example 4, the presence of numerous black debris around the pores in the coating indicates weak adhesion of the β-Ta coating without a primer layer. The experimental results directly demonstrate that a titanium-tantalum mixed primer layer significantly improves the interfacial bonding between the coating and the sandblasted and acid-etched substrate, meeting the requirements of high-torque implants.

[0064] In Example 5, a small amount of black debris appeared around the pores of the coating, indicating poor bonding strength. This phenomenon may also be due to the low thickness of the coating deposited by the low target current (about 100 nm), which made it difficult to observe.

[0065] In Example 6, the coating has the most black debris around the pores and the worst bonding strength. This phenomenon may be because high target current usually leads to an accelerated coating deposition rate, insufficient atomic migration time, and higher residual stress may be formed inside the coating.

[0066] When there is no base layer, the high interface energy caused by the high lattice mismatch (10.6%) promotes the formation of β-Ta phase; after introducing titanium or titanium-tantalum base layer, the nucleation energy barrier of α-Ta phase is reduced through interface diffusion (pure titanium layer) or low-energy deposition environment (titanium-tantalum mixed layer), realizing the controllable growth of α phase. Among them, the crystallinity of α phase is optimal when the titanium-tantalum mixed layer is combined with a negative bias of 60V.

[0067] In summary, the present invention achieves precise control of the tantalum coating phase under low-temperature conditions through the coordinated regulation of the base layer composition and the negative bias voltage of the substrate through low-temperature magnetron sputtering technology. At the same time, it achieves the optimization of the crystallinity of the α-Ta phase by the titanium-tantalum mixed base layer system, as well as the excellent bonding performance (no debris peeling) of the sandblasted and acid-etched dental implant surface during high-torque implantation. The experimental results provide an industrializable technical solution for the surface modification of biomedical implants that is both scientifically innovative and clinically practical.

Claims

1. A method for controlling the phase of tantalum coating used in sandblasted and acid-etched titanium alloy dental implants based on low-temperature magnetron sputtering, characterized in that: The low-temperature magnetron sputtering technology is used, which includes the following steps: (1) Pretreatment: high-energy bombardment of the substrate material; (2) Controlling the tantalum coating phase to be β phase: depositing a tantalum coating on the surface of the pretreated substrate; (3) Regulating the tantalum coating phase to be α phase: first depositing a base layer on the surface of the pretreated substrate, and then depositing the elemental tantalum coating; In step (1), the process parameters of the high-energy bombardment are: argon ions are used for high-energy bombardment, the flow rate is 30sccm~60sccm, the chamber pressure is 0.1Pa~0.4Pa, the substrate negative bias is 200V~800V, the tantalum target current is 0.1A~1A, and the time is 20~40min; the substrate material is selected from 316L stainless steel or titanium alloy; in steps (2) to (3), the deposition temperature is lower than 100°C, the target-substrate distance is 10cm~15cm, the substrate negative bias is 30V~90V, and the total thickness of the coating is 100nm~1000nm; the bottom layer is a single titanium metal layer or a titanium-tantalum mixed metal layer; the deposition parameters of the single titanium metal layer are: the titanium target current is 6~8A, and the deposition time is 1min~10min; the deposition parameters of the titanium-tantalum mixed metal layer are: the titanium target current is 6~8A, the tantalum target current is gradually increased from 0A to 1A~4A, and the deposition time is 1 min~10min; the deposition parameters of the elemental tantalum coating are: tantalum target current is 1A~4A, and deposition time is 30min~80min.

2. A tantalum coating obtained by the control method according to claim 1.

Images