Electrolytic coloring composite treatment method for stainless steel instrument and stainless steel oral medical instrument prepared by adopting method

Abstract

The invention relates to a stainless steel instrument electrolytic coloring composite treatment method and a stainless steel oral medical instrument prepared by the method, the treatment method comprises the following steps: (1) roughening pretreatment to obtain a clean and rough surface; (2) PVD film plating treatment: plasma cleaning is performed on the pretreated stainless steel instrument, and a PVD tantalum coating is locally deposited on the stainless steel instrument in a magnetron sputtering or arc ion plating mode; (3) one-step electrolytic coloring compound treatment is carried out, and anodic oxidation coloring of the tantalum coating area and electrochemical polishing of the exposed stainless steel area are synchronously achieved; and (4) post-treatment is conducted, specifically, the electrolyzed stainless steel instrument is neutralized, cleaned and dried. Through the innovative one-step electrolytic coloring composite treatment technology, the long-term safety and applicability of the instrument are remarkably improved, the traditional contradiction between the coating binding force and the surface smoothness and antibacterial property is ingeniously solved, and industrial application prospects are achieved.

Description

Technical Field

[0001] This invention relates to the field of metal surface treatment technology, specifically to a method for electrolytic coloring composite treatment of stainless steel medical devices and stainless steel dental medical devices prepared using this method. Background Technology

[0002] Stainless steel is widely used in dental medical devices such as surgical forceps, dental tools, and orthodontic brackets due to its advantages of high strength, ease of processing, and moderate cost. However, conventional stainless steel materials have two major shortcomings: first, in the oral fluid environment, its surface corrosion resistance and biocompatibility are insufficient, and it is easy to leach nickel and chromium ions, which may cause sensitization risks; second, its surface color is limited, making it difficult to meet the labeling requirements of dental instruments that "distinguish colors according to function".

[0003] To address these issues, the industry widely employs surface coating technology for performance optimization. Among these, physical vapor deposition (PVD) has become the mainstream choice due to its high-purity coatings, excellent adhesion, and environmentally friendly process. Tantalum coatings, with their good bioinertness and anticoagulant properties, are considered ideal materials for dental instrument coatings. However, PVD-prepared tantalum coatings are typically silver-gray due to the inherent limitations of the material. Achieving a colored appearance requires multiple layers of coating or repeated plating, leading to complex processes, increased costs, longer production cycles, and potentially weakened coating adhesion and performance stability.

[0004] While colored anodizing technology can produce rich colors through optical interference effects, and the colors are durable and wear-resistant, its applicability is limited to metals such as aluminum, titanium, and magnesium. Stainless steel surfaces, due to the dense Cr2O3 passivation film, have poor ionic conductivity, making it impossible to achieve stable and controllable color effects directly in a single anodizing solution. Existing improved methods, such as "anodizing after electroplating an aluminum layer on the stainless steel surface," face problems such as weak adhesion of the electroplated layer, easy peeling, and insufficient corrosion resistance due to the amphoteric nature of the aluminum oxide film, making it difficult to meet the stringent requirements of dental medical devices.

[0005] In addition, there is a key contradiction in the application of coatings for dental medical devices: improving the adhesion between the coating and the stainless steel substrate usually requires roughening the substrate surface to enhance adhesion by increasing the mechanical interlocking and contact area at the interface; however, a rough surface is prone to the adhesion and colonization of oral bacteria, increasing the risk of infection. Therefore, the surface of the non-implanted part of the device must have a smooth characteristic with low roughness.

[0006] Therefore, there is an urgent need to develop a comprehensive treatment technology that can simultaneously resolve the contradictions between corrosion resistance, biocompatibility, color identification, and surface characteristics of stainless steel dental medical devices. Summary of the Invention

[0007] This invention addresses the problems of poor corrosion resistance, insufficient biocompatibility (easily releasing nickel and chromium ions and causing sensitization risks), limited surface color (difficult to meet functional identification requirements), and the contradiction between coating adhesion and surface smoothness and antibacterial properties (rough surfaces may improve adhesion but are prone to bacterial growth) in existing stainless steel dental medical devices. It provides an electrolytic coloring composite treatment method for stainless steel devices and corresponding stainless steel dental medical devices. Through process innovation, it simultaneously solves performance shortcomings and technical contradictions, resulting in products that combine safety protection, functional identification, and biocompatibility.

[0008] The specific process includes: first, surface roughening pretreatment of the stainless steel substrate to ensure the adhesion of the subsequent tantalum coating; then, deposition of the tantalum coating using PVD process; finally, a one-time electrochemical treatment is carried out through customized solution formulation and process parameters to simultaneously achieve two major goals: first, anodizing and coloring of designated areas of the tantalum coating to meet color identification requirements; and second, electrochemical polishing of exposed stainless steel areas (areas not covered by the tantalum coating) to obtain a smooth surface with low roughness, thereby reducing bacterial colonization.

[0009] This technology, through systematic design, addresses the long-standing contradiction between coating adhesion and surface smoothness and antibacterial properties. Roughening pretreatment ensures adhesion, while one-step electrolytic coloring composite treatment achieves surface smoothness. On the other hand, it integrates the two key steps of coloring and polishing into a single process, simplifying the workflow, improving efficiency, and reducing costs. It also avoids the potential impact of multiple processes on coating performance, thus providing a comprehensive solution for stainless steel dental medical devices that combines high-performance protection, stable color appearance, and good biocompatibility.

[0010] The core technical solution of this invention is a method for electrolytic coloring and composite treatment of stainless steel instruments, specifically including the following steps:

[0011] (1) Roughening pretreatment: The stainless steel instruments are subjected to wet sandblasting, degreasing and oil removal and purified water washing and drying in sequence; (2) PVD coating treatment: After plasma cleaning of the pretreated stainless steel instruments, PVD tantalum coating is deposited locally on the stainless steel instruments by magnetron sputtering or arc ion plating. (3) One-step electrolytic coloring composite treatment: Prepare an anolyte, use the PVD coated stainless steel instrument as the anode and the stainless steel plate as the cathode for electrochemical treatment, and simultaneously realize the anodizing coloring of the tantalum coating area and the electrochemical polishing of the exposed stainless steel area; wherein, the anolyte contains sulfuric acid with a concentration of 50~200g / L, phosphoric acid with a concentration of 30~150g / L, formic acid with a concentration of 35~180g / L, oxalic acid with a concentration of 20~100g / L, citric acid with a concentration of 5~100g / L, and also contains corrosion inhibitors; (4) Post-treatment: Neutralize, clean and dry the stainless steel instruments after electrolysis.

[0012] Furthermore, in step (1), the abrasive material used for wet sandblasting is alumina or ceramic sand, the abrasive particle size is 80~450 mesh, the sandblasting pressure is 0.1~0.6MPa, and the sandblasting distance is 20~300mm.

[0013] Furthermore, in step (1), the alkaline degreasing agent is composed of 5~50g / L sodium hydroxide, 2~30g / L sodium carbonate, 1~25g / L sodium pyrophosphate and 0.5~30g / L sodium dodecylbenzenesulfonate, the degreasing temperature is 30~70℃, and the ultrasonic cleaning time is 5~30min.

[0014] Furthermore, in step (2), the Ar gas inlet for ion cleaning is 2~30 SCCM, the bias voltage is 200~1000V, the rotating cathode / arc current is 0.5~5A, and the cleaning time is 5~60min.

[0015] Furthermore, in step (2), the target material for PVD coating is Ta, the Ar inlet gas volume is 10~200SCCM, the bias voltage is 50~400V, the rotating cathode current is 3~20A, the coating temperature is 120~350℃, and the coating time is 60~450min, resulting in a Ta coating with a thickness of 0.1~100μm and a surface roughness of 1.0~2.0μm.

[0016] Furthermore, in the anolyte described in step (3), the concentration of sulfuric acid is 100~200g / L, the concentration of phosphoric acid is 50~100g / L, the concentration of formic acid is 50~150g / L, the concentration of oxalic acid is 30~70g / L, and the concentration of citric acid is 20~100g / L; Preferably, the anolyte further comprises a conductive agent and a thickener, wherein the conductive agent is ethylene glycol with a concentration of 1~60 g / L; and the thickener is glycerol with a concentration of 1~50 mL / L. Preferably, the corrosion inhibitor is sodium silicate with a concentration of 3~25 g / L.

[0017] Furthermore, in step (3), the electrochemical treatment temperature is 10~50℃, the time is 0.5~10min, the oxidation voltage is 1~150V, the thickness of the anodic oxide film generated in the tantalum coating area is 0.2~5μm, and the surface roughness of the exposed stainless steel area is ≤0.2μm.

[0018] Furthermore, in step (3), the tantalum coating area is made to appear in different colors by adjusting the oxidation voltage, including: 8~14V is yellow, 16~24V is golden yellow, 27~32V is purple, 35~45V is magenta, 48~55V is blue, 62~68V is light blue, 97~102V is magenta, and 116~123V is blue-green.

[0019] Furthermore, in step (4), the neutralization is carried out using a sodium bicarbonate solution of 10~300g / L or a sodium carbonate solution of 5~200g / L, the neutralization temperature is 20~60℃, and the neutralization time is 0.5~5min.

[0020] This invention also protects the stainless steel instruments obtained by the aforementioned processing method. The stainless steel instruments are dental medical devices, including surgical forceps, dental tools, or orthodontic brackets. The areas of the stainless steel substrate not covered by the tantalum coating are electrochemically polished smooth surfaces with a surface roughness ≤0.2μm. The areas covered by the tantalum coating have an anodized coloring film. The colored areas meet the requirement of no significant fading after 50 high-temperature and high-pressure tests. The high-temperature and high-pressure test temperature is 132~134℃, the high-temperature and high-pressure time is 4min, the drying time is 30min, and the pressure is 0.21~0.22MPa. Furthermore, the corrosion resistance meets the requirement of no corrosion after more than 72 hours of neutral salt spray testing.

[0021] Beneficial effects Stainless steel dental medical devices face key challenges in performance optimization, primarily including insufficient corrosion resistance and biocompatibility of the substrate, as well as the lack of surface functional markings. This invention systematically solves these problems through an innovative one-step electrolytic coloring composite treatment technology, achieving a balance between process efficiency and overall performance.

[0022] Compared with the prior art, the present invention has the following beneficial effects: First, it significantly improves the long-term safety and suitability of the device. The PVD-deposited tantalum coating effectively isolates the stainless steel substrate from the oral fluid environment, fundamentally preventing the leaching of nickel and chromium ions and reducing the risk of sensitization. The inherent bioinertness of tantalum further ensures the stable performance of the device in complex physiological environments. Simultaneously, anodizing the tantalum-coated areas allows for a wide range of color choices, not only meeting the clinical needs for functional zoning and improving operational efficiency, but also providing the resulting oxide film with excellent wear resistance and color retention, ensuring the color remains vibrant even after repeated use and sterilization.

[0023] Secondly, it cleverly resolves the traditional contradiction between "coating adhesion" and "surface smoothness and antibacterial properties." By first subjecting the stainless steel substrate to controlled roughening pretreatment, a solid mechanical anchoring foundation is provided for the subsequent PVD tantalum coating, ensuring its high adhesion. In the subsequent one-step electrolytic coloring process, only the uncoated exposed stainless steel areas are selectively polished to achieve a smooth state with low roughness, thereby effectively reducing the risk of bacterial adhesion and colonization, while completely preserving the interfacial stability of the deposited coating. This design achieves a balance between protective performance and surface biosafety.

[0024] Finally, it simplifies the process, reduces costs, increases efficiency, and enhances industrial value. It integrates the key coloring and electrolysis steps into a single process, avoiding the complex procedures of traditional multi-process, multi-coating stacking. This not only simplifies production steps and reduces equipment investment and energy consumption but also significantly shortens the production cycle, making it more suitable for the high-precision, high-volume manufacturing needs of medical devices. The simplified process also reduces interface defects and performance fluctuations that may be introduced by multiple processing steps, ensuring the consistency and reliability of product quality.

[0025] In summary, this invention not only improves the corrosion resistance, biocompatibility, and functional identification of the device through material and structural design, but also efficiently coordinates multiple requirements such as coating adhesion, surface smoothness, and antibacterial properties through innovative process routes. Furthermore, it achieves the best balance between performance, efficiency, and cost through an intensive process, providing a practical and feasible system solution for the upgrade of high-end stainless steel dental medical devices.

[0026] In terms of product performance, compared with conventional PVD coating technology, this invention can achieve a colored appearance without repeated coating, and the coating adhesion is improved by more than 30%; compared with the anodizing technology after electroplating aluminum layer on stainless steel, the corrosion resistance is significantly improved, and the neutral salt spray test can reach more than 150 hours, and the coating adhesion is stronger with no risk of peeling; compared with simple roughening treatment, the surface smoothness is improved by more than 60%, and the amount of bacterial adhesion can be significantly reduced by at least 30%. Attached Figure Description

[0027] Figure 1 is a schematic diagram of the structure of the stainless steel dental medical device of the present invention. Detailed Implementation

[0028] The present invention will be further described in detail below with reference to specific embodiments and comparative examples. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions. Where the manufacturers of reagents or instruments are not specified, they are all commercially available conventional products. In the following embodiments, unless otherwise specified, "%" refers to weight percentage. The high-temperature and high-pressure test is conducted at a temperature of 132~134℃, a pressure of 0.21~0.22MPa, and a high-temperature and high-pressure time of 4 minutes, followed by drying at the maintained temperature for 30 minutes.

[0029] Example 1 An electrolytic coloring composite treatment for stainless steel support nails, comprising the following steps: (1) The stainless steel anchor pins were placed in a sandblasting machine and sandblasted with 150μm ceramic sand at a pressure of 0.5MPa and a distance of 50mm. Then, the sandblasted anchor pins were placed in an alkaline degreasing agent and placed in an ultrasonic cleaning device. The alkaline degreasing agent consisted of 40g / L sodium hydroxide, 20g / L sodium carbonate, 15g / L sodium pyrophosphate and 10g / L surfactant. The ultrasonic cleaning temperature was adjusted to 60℃, the ultrasonic power to 300W and the cleaning time to 15min. This step removed the oil stains, residual alumina particles and other impurities attached to the surface of the anchor pins. Finally, the degreased and deoiled stainless steel anchor pins were transferred to a purified water ultrasonic cleaning tank. The cleaning temperature was adjusted to 60℃, the ultrasonic power to 250W and the cleaning time to 10min. After cleaning, the anchor pins were placed in a forced-air drying oven. The drying temperature was set to 120℃ and the drying time to 30min to ensure that there was no residual moisture and soluble impurities on the surface of the anchor pins.

[0030] (2) Place the stainless steel support nails, which have been rinsed and dried with purified water, into the vacuum chamber of the PVD coating equipment, close the vacuum chamber and evacuate to a vacuum degree ≤ 5×10. - ³Pa; Ar gas is introduced as the cleaning gas, the Ar gas inlet is adjusted to 15SCCM, the substrate bias voltage is set to 600V, the rotating cathode current is 2A, and plasma deep cleaning is performed for 20min; this step deeply removes residual oil, moisture and weakly adsorbed organic impurities from the substrate surface, while activating the substrate surface and improving the deposition quality of subsequent film layers.

[0031] After plasma cleaning, the vacuum level in the vacuum chamber was kept constant, and a PVD coating was deposited using magnetron sputtering with Ta as the target material. The Ar gas inlet was adjusted to 80 SCCM, the substrate bias voltage was 200 V, the rotating cathode current was 10 A, the coating temperature was controlled at 250 °C, and the coating time was 200 min. Finally, a Ta coating with a thickness of 1.0 μm was deposited on the surface of the stainless steel support nail.

[0032] (3) First, prepare the anolyte, which consists of: 120 g / L sulfuric acid, 80 g / L phosphoric acid, 100 g / L formic acid, 50 g / L oxalic acid, 50 g / L citric acid, 30 g / L ethylene glycol to adjust the conductivity of the solution, 25 mL / L glycerol as a thickener, and 15 g / L sodium silicate as a corrosion inhibitor. Add each component to purified water in sequence, stir until completely dissolved, and let stand for 30 min to degas before use.

[0033] Secondly, using PVD-coated stainless steel support nails as anodes and 316 stainless steel plates as cathodes, the two electrodes were placed parallel to each other in the prepared anolyte with a distance of 40 cm between them. A DC power supply was connected, the electrolysis temperature was adjusted to 30°C, the oxidation voltage was set to 30V, and the electrolysis time was 1 min. Through this treatment, a purple anodic oxide film was generated on the surface, and the uncoated threaded area of ​​the support nail was smoothed, with the roughness reduced from 1.0 μm to 0.2 μm.

[0034] (4) Take out the stainless steel support nails after anodizing / electrolysis and put them into a 100g / L sodium bicarbonate solution for neutralization treatment. The neutralization solution temperature is room temperature and the neutralization time is 2min. After neutralization, rinse with purified water 5 times, each rinse time is 1min. Finally, put the support nails into a forced-air drying oven, set the drying temperature to 80℃ and the drying time to 20min to obtain the finished stainless steel support nails after surface modification treatment.

[0035] See the structural diagram of the finished stainless steel support nail. Figure 1 The threaded areas have a PVD tantalum coating, which forms an anodic oxide coloring film during electrolysis, resulting in a purple color. The remaining areas do not have a PVD tantalum coating and are exposed. The exposed areas are electrochemically polished during electrolysis to achieve a smooth, bright surface, with the roughness decreasing from 1.0 μm before electrolysis to 0.2 μm after electrolysis. The colored areas showed no corrosion after 150 hours of neutral salt spray testing and no fading after 80 high-temperature and high-pressure tests.

[0036] It should be noted that in other embodiments, the threaded area may be designed as an exposed area, while the remaining areas may be designed as colored areas, depending on the specific application scenario of the product.

[0037] Example 2 An electrolytic coloring composite treatment for stainless steel surgical forceps, comprising the following steps: (1) Roughening pretreatment: 200 mesh alumina sand was used for sandblasting at a pressure of 0.3 MPa and a distance of 100 mm; the alkaline degreasing agent consisted of 30 g / L sodium hydroxide, 15 g / L sodium carbonate, 10 g / L sodium pyrophosphate, and 8 g / L sodium dodecylbenzene sulfonate. The mixture was ultrasonically cleaned at 50°C for 20 min; ultrasonically cleaned with purified water at 70°C for 15 min; and dried at 100°C for 20 min.

[0038] (2) PVD coating treatment: Ar gas inlet 20SCCM, bias voltage 500V, rotating cathode current 3A, plasma cleaning 15min; using Ti as target material, Ar gas inlet 100SCCM, bias voltage 150V, rotating cathode current 12A, coating at 200℃ for 180min to form a 0.8μm thick Ti coating.

[0039] (3) One-step electrolytic coloring composite treatment: The anolyte consists of 80 g / L sulfuric acid, 60 g / L phosphoric acid, 60 g / L citric acid, 20 g / L ethylene glycol, 15 mL / L glycerol, and 10 g / L sodium silicate; electrolysis is performed at 25℃ and 20V for 3 min to form a golden yellow anodic oxide film.

[0040] (4) Post-treatment: neutralize with 50 g / L sodium carbonate solution at 40 °C for 3 min, rinse 4 times with purified water, and dry at 90 °C for 15 min.

[0041] After treatment, the surgical forceps were uniformly colored, and the roughness of the exposed area decreased from 1.0 μm before electrolysis to 0.18 μm after electrolysis. The colored area showed no corrosion after 120 hours of neutral salt spray testing and no fading after 60 high-temperature and high-pressure tests.

[0042] Example 3 An electrolytic coloring composite treatment for stainless steel dental tweezers, the steps of which are as follows: (1) Roughening pretreatment: 400 mesh ceramic sand, pressure 0.2MPa, distance 80mm sandblasting; alkaline degreasing agent composition is 20g / L sodium hydroxide, 10g / L sodium carbonate, 8g / L sodium pyrophosphate, 5g / L sodium dodecylbenzenesulfonate, ultrasonic cleaning at 40℃ for 25min; ultrasonic cleaning with purified water at 50℃ for 20min, drying at 80℃ for 40min.

[0043] (2) PVD coating treatment: Ar gas inlet 10 SCCM, bias voltage 400V, rotating cathode current 1.5A, plasma cleaning 25min; using Ta as target material, Ar gas inlet 60 SCCM, bias voltage 100V, rotating cathode current 8A, coating at 220℃ for 250min to form a 1.2μm thick Ta coating.

[0044] (3) One-step electrolytic coloring composite treatment: The anolyte composition is 100g / L phosphoric acid, 80g / L formic acid, 40g / L oxalic acid, 25g / L ethylene glycol, 20mL / L glycerol, and 12g / L sodium silicate; electrolysis is performed at 35℃ and 40V for 2min to form a magenta anodic oxide film.

[0045] (4) Post-treatment: neutralize with 150 g / L sodium bicarbonate solution at 30 °C for 1.5 min, rinse 5 times with purified water, and dry at 100 °C for 12 min.

[0046] After treatment, the tweezers surface is smooth, and the roughness of the exposed area is reduced from 1.0 μm before electrolysis to 0.12 μm after electrolysis. The colored area shows no corrosion after 150 hours of neutral salt spray testing and no fading after 80 high temperature and high pressure tests.

[0047] Example 4 An electrolytic coloring composite treatment for stainless steel orthodontic brackets, comprising the following steps: (1) Roughening pretreatment: 80 mesh alumina sand, blasting at a pressure of 0.6 MPa and a distance of 20 mm; alkaline degreasing agent composed of 50 g / L sodium hydroxide, 30 g / L sodium carbonate, 25 g / L sodium pyrophosphate, and 30 g / L sodium dodecylbenzene sulfonate, ultrasonic cleaning at 70℃ for 5 min; ultrasonic cleaning with purified water at 80℃ for 2 min, and drying at 140℃ for 10 min.

[0048] (2) PVD coating treatment: Ar gas inlet 30SCCM, bias voltage 1000V, rotating cathode current 5A, plasma cleaning for 5min; using Ti as target material, Ar gas inlet 200SCCM, bias voltage 400V, rotating cathode current 20A, coating at 350℃ for 60min to form a 0.5μm thick Ti coating.

[0049] (3) One-step electrolytic coloring composite treatment: The anolyte consists of 200 g / L sulfuric acid, 150 g / L phosphoric acid, 180 g / L formic acid, 100 g / L oxalic acid, 60 g / L ethylene glycol, 50 mL / L glycerol, and 25 g / L sodium silicate; electrolysis is performed at 50℃ and 50V for 0.5 min to form a blue anodic oxide film.

[0050] (4) Post-treatment: neutralize with 200g / L sodium carbonate solution at 60℃ for 0.5min, rinse 3 times with purified water, and dry at 120℃ for 10min.

[0051] After treatment, the corrosion resistance of the brackets meets the requirements for use in the oral environment, and the color is uniform and stable. The roughness of the exposed area decreased from 1.0μm before electrolysis to 0.16μm after electrolysis. The stained area showed no corrosion after 72 hours of neutral salt spray testing and no fading after 60 high-temperature and high-pressure tests.

[0052] Example 5 An electrolytic coloring composite treatment for a stainless steel dental probe, comprising the following steps: (1) Roughening pretreatment: 450 mesh ceramic sand, pressure 0.1MPa, distance 300mm sandblasting; alkaline degreasing agent composition is 5g / L sodium hydroxide, 2g / L sodium carbonate, 1g / L sodium pyrophosphate, 0.5g / L sodium dodecylbenzenesulfonate, ultrasonic cleaning at 30℃ for 30min; ultrasonic cleaning with purified water at 30℃ for 30min, drying at 60℃ for 60min.

[0053] (2) PVD coating treatment: Ar gas inlet 2SCCM, bias voltage 200V, rotating cathode current 0.5A, plasma cleaning for 60min; using Ta as target material, Ar gas inlet 10SCCM, bias voltage 50V, rotating cathode current 3A, coating at 120℃ for 450min to form a 1.5μm thick Ta coating.

[0054] (3) One-step electrolytic coloring composite treatment: The anolyte composition is 50 g / L sulfuric acid, 30 g / L phosphoric acid, 35 g / L formic acid, 20 g / L oxalic acid, 5 g / L citric acid, 1 g / L ethylene glycol, 1 mL / L glycerol, and 3 g / L sodium silicate; electrolysis is performed at 10℃ and 12V for 10 min to form a yellow anodic oxide film.

[0055] (4) Post-treatment: neutralize with 10 g / L sodium bicarbonate solution at 20℃ for 5 min, rinse 5 times with purified water, and dry at 60℃ for 30 min.

[0056] The treated probe surface is smooth and free of impurities, exhibiting excellent biocompatibility and no nickel or chromium ion precipitation. The roughness of the exposed area decreased from 1.0 μm before electrolysis to 0.13 μm after electrolysis. The colored area showed no corrosion after 144 hours of neutral salt spray testing and no fading after 60 high-temperature and high-pressure tests.

[0057] Example 6 An electrolytic coloring composite treatment for a stainless steel root canal file, comprising the following steps: (1) Roughening pretreatment: 300 mesh alumina sand, pressure 0.4MPa, distance 150mm sandblasting; alkaline degreasing agent composition is 35g / L sodium hydroxide, 25g / L sodium carbonate, 20g / L sodium pyrophosphate, 15g / L sodium dodecylbenzenesulfonate, ultrasonic cleaning at 55℃ for 12min; ultrasonic cleaning with purified water at 65℃ for 12min, drying at 90℃ for 25min.

[0058] (2) PVD coating treatment: Ar gas inlet 25SCCM, bias voltage 800V, rotating cathode current 4A, plasma cleaning for 10min; using Ti as target material, Ar gas inlet 150SCCM, bias voltage 300V, rotating cathode current 15A, coating at 300℃ for 150min to form a 0.9μm thick Ti coating.

[0059] (3) One-step electrolytic coloring composite treatment: The anolyte composition is 150g / L sulfuric acid, 100g / L phosphoric acid, 120g / L citric acid, 40g / L ethylene glycol, 30mL / L glycerol, and 20g / L sodium silicate; electrolysis is performed at 40℃ and 65V for 4min to form a light blue anodic oxide film.

[0060] (4) Post-treatment: neutralize with 80 g / L sodium carbonate solution at 50 °C for 2 min, rinse 4 times with purified water, and dry at 100 °C for 18 min.

[0061] After treatment, the root canal file was uniformly stained, with no significant change in rigidity. The roughness of the exposed area decreased from 1.0 μm before electrolysis to 0.15 μm after electrolysis. The stained area showed no corrosion after 100 hours of neutral salt spray testing and no fading after 50 high-temperature and high-pressure tests.

[0062] Example 7 An electrolytic coloring composite treatment for a stainless steel periodontal scaling instrument, comprising the following steps: (1) Roughening pretreatment: 100 mesh ceramic sand, pressure 0.25MPa, distance 70mm sandblasting; alkaline degreasing agent composition is 25g / L sodium hydroxide, 12g / L sodium carbonate, 12g / L sodium pyrophosphate, 6g / L sodium dodecylbenzenesulfonate, ultrasonic cleaning at 45℃ for 18min; ultrasonic cleaning with purified water at 55℃ for 18min, drying at 110℃ for 22min.

[0063] (2) PVD coating treatment: Ar gas inlet 18SCCM, bias voltage 700V, rotating cathode current 2.5A, plasma cleaning 18min; using Ta as target material, Ar gas inlet 90SCCM, bias voltage 250V, rotating cathode current 9A, coating at 280℃ for 220min to form a 1.1μm thick Ta coating.

[0064] (3) One-step electrolytic coloring composite treatment: The anolyte composition is 90 g / L phosphoric acid, 90 g / L formic acid, 30 g / L oxalic acid, 28 g / L ethylene glycol, 18 mL / L glycerol, and 14 g / L sodium silicate; electrolysis is performed at 32℃ and 100V for 2.5 min to form a magenta anodic oxide film.

[0065] (4) Post-treatment: neutralize with 120 g / L sodium bicarbonate solution at 35 °C for 2.5 min, rinse with purified water 5 times, and dry at 85 °C for 22 min.

[0066] After treatment, the roughness of the exposed area of ​​the scraper decreased from 1.0 μm before electrolysis to 0.14 μm after electrolysis, significantly reducing bacterial adhesion and improving clinical safety. The stained area showed no corrosion after 150 hours of neutral salt spray testing and no fading after 50 high-temperature and high-pressure tests.

[0067] Example 8 An electrolytic coloring and lamination process for a stainless steel interlocking paper clip includes the following steps: (1) Roughening pretreatment: 250 mesh alumina sand, pressure 0.35MPa, distance 120mm sandblasting; alkaline degreasing agent composition is 32g / L sodium hydroxide, 18g / L sodium carbonate, 14g / L sodium pyrophosphate, 9g / L sodium dodecylbenzenesulfonate, ultrasonic cleaning at 52℃ for 16min; ultrasonic cleaning with purified water at 62℃ for 14min, drying at 95℃ for 28min.

[0068] (2) PVD coating treatment: Ar gas inlet 22SCCM, bias voltage 550V, rotating cathode current 3.5A, plasma cleaning 12min; using Ti as target material, Ar gas inlet 120SCCM, bias voltage 180V, rotating cathode current 13A, coating at 240℃ for 190min to form a 0.7μm thick Ti coating.

[0069] (3) One-step electrolytic coloring composite treatment: The anolyte composition is 110 g / L sulfuric acid, 70 g / L phosphoric acid, 70 g / L citric acid, 35 g / L ethylene glycol, 22 mL / L glycerol, and 16 g / L sodium silicate; electrolysis is carried out at 28℃ and 120V for 3.5 min to form a blue-green anodic oxide film.

[0070] (4) Post-treatment: neutralize with 60 g / L sodium carbonate solution at 45℃ for 1.8 min, rinse 4 times with purified water, and dry at 92℃ for 16 min.

[0071] The treated interlocking paper clips exhibit vibrant colors and wear resistance suitable for repeated clinical use. The roughness of the exposed areas decreased from 1.0 μm before electrolysis to 0.18 μm after electrolysis, eliminating the risk of bacterial growth. The colored areas showed no corrosion after 144 hours of neutral salt spray testing and no fading after 60 high-temperature and high-pressure cycles.

[0072] Comparative Example 1 Compared to Example 1, no roughening pretreatment was performed; PVD coating and electrolysis were carried out directly, as detailed below: (1) Cleaning pretreatment: Place the stainless steel support nails in an alkaline degreasing agent (40g / L sodium hydroxide, 20g / L sodium carbonate, 15g / L sodium pyrophosphate, 10g / L sodium dodecylbenzene sulfonate), and ultrasonically clean them at 60℃ for 15min; then ultrasonically clean them with purified water at 60℃ for 10min, and dry them at 120℃ for 30min.

[0073] (2) PVD coating treatment: The support pins are placed in the PVD vacuum chamber, the Ar gas inlet is 15 SCCM, the bias voltage is 600V, the rotating cathode current is 2A, and the plasma cleaning is performed for 20 min; using Ta as the target material, the Ar gas inlet is 80 SCCM, the bias voltage is 200V, the rotating cathode current is 10A, and the coating is performed at 250℃ for 200 min to form a 1.0μm thick Ta coating.

[0074] (3) One-step electrolytic coloring composite treatment: Prepare anolyte (120g / L sulfuric acid, 80g / L phosphoric acid, 100g / L formic acid, 50g / L oxalic acid, 50g / L citric acid, 30g / L ethylene glycol, 25mL / L glycerol, 15g / L sodium silicate); use anchor nails as anodes and 316 stainless steel plates as cathodes, with a spacing of 40cm, electrolyze at 30℃ and 30V for 1min to form a purple anodic oxide film.

[0075] (4) Post-treatment: neutralize in 100g / L sodium bicarbonate solution at room temperature for 2min, rinse 5 times with purified water, and dry at 80℃ for 20min.

[0076] Results: The adhesion of the Ta coating decreased significantly, and localized corrosion occurred in the colored area after 96 hours of neutral salt spray testing. Since the surface roughness of the exposed area did not increase, there was a risk of increased bacterial adhesion.

[0077] Comparative Example 2 Compared to Example 1, sodium silicate was not added to the anolyte, but the remaining steps were the same. Specifically: (1) Roughening pretreatment: The stainless steel support nails were placed in a sandblasting machine and sandblasted with 150μm ceramic sand at a pressure of 0.5MPa and a distance of 50mm. Then, an alkaline degreasing agent (40g / L sodium hydroxide, 20g / L sodium carbonate, 15g / L sodium pyrophosphate, 10g / L sodium dodecylbenzenesulfonate) was added and ultrasonically cleaned at 60℃ for 15min. Then, the mixture was ultrasonically cleaned with purified water at 60℃ for 10min and dried at 120℃ for 30min.

[0078] (2) PVD coating treatment: The support pins are placed in the PVD vacuum chamber, the Ar gas inlet is 15 SCCM, the bias voltage is 600V, the rotating cathode current is 2A, and the plasma cleaning is performed for 20 min; using Ta as the target material, the Ar gas inlet is 80 SCCM, the bias voltage is 200V, the rotating cathode current is 10A, and the coating is performed at 250℃ for 200 min to form a 1.0μm thick Ta coating.

[0079] (3) One-step electrolytic coloring composite treatment: Prepare anolyte (120g / L sulfuric acid, 80g / L phosphoric acid, 100g / L formic acid, 50g / L oxalic acid, 50g / L citric acid, 30g / L ethylene glycol, 25mL / L glycerol); use anchor nails as anodes and 316 stainless steel plates as cathodes with a spacing of 40cm, electrolyze at 30℃ and 30V for 1min to form a purple anodic oxide film.

[0080] (4) Post-treatment: neutralize in 100g / L sodium bicarbonate solution at room temperature for 2min, rinse 5 times with purified water, and dry at 80℃ for 20min.

[0081] Results: Uneven transition occurred at the boundary between the colored area and the bare area. The surface roughness of the bare area was 0.6 μm, and haze appeared in the bare area, which did not meet the gloss standard of electropolishing.

[0082] Comparative Example 3 Compared to Example 1, citric acid and oxalic acid were not added to the anolyte; instead, an equal amount of phosphoric acid was used instead. The remaining steps were the same. Specifically: (1) Roughening pretreatment: The stainless steel support nails were placed in a sandblasting machine and sandblasted with 150μm ceramic sand at a pressure of 0.5MPa and a distance of 50mm. Then, an alkaline degreasing agent (40g / L sodium hydroxide, 20g / L sodium carbonate, 15g / L sodium pyrophosphate, 10g / L sodium dodecylbenzenesulfonate) was added and ultrasonically cleaned at 60℃ for 15min. Then, the mixture was ultrasonically cleaned with purified water at 60℃ for 10min and dried at 120℃ for 30min.

[0083] (2) PVD coating treatment: The support pins are placed in the PVD vacuum chamber, the Ar gas inlet is 15 SCCM, the bias voltage is 600V, the rotating cathode current is 2A, and the plasma cleaning is performed for 20 min; using Ta as the target material, the Ar gas inlet is 80 SCCM, the bias voltage is 200V, the rotating cathode current is 10A, and the coating is performed at 250℃ for 200 min to form a 1.0μm thick Ta coating.

[0084] (3) One-step electrolytic coloring composite treatment: Prepare anolyte (120g / L sulfuric acid, 180g / L phosphoric acid, 100g / L formic acid, 30g / L ethylene glycol, 25mL / L glycerol, 15g / L sodium silicate); use anchor nails as anodes and 316 stainless steel plates as cathodes with a spacing of 40cm, electrolyze at 30℃ and 30V for 1min to form a purple anodic oxide film.

[0085] (4) Post-treatment: neutralize in 100g / L sodium bicarbonate solution at room temperature for 2min, rinse 5 times with purified water, and dry at 80℃ for 20min.

[0086] Results: The conductivity of the solution was unstable during electrolysis, the coloring uniformity was poor, and color difference appeared; the corrosion resistance of the anodic oxide film was insufficient, and pitting corrosion appeared after 72 hours of neutral salt spray testing; the polishing effect of the uncoated area was poor, the roughness was only reduced to 0.5 μm, and the amount of bacterial adhesion was not effectively controlled.

[0087] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0088] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0089] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A method for electrolytic coloring composite treatment of stainless steel instruments, characterized in that, Includes the following steps: (1) Roughening pretreatment: The stainless steel instruments are subjected to wet sandblasting, degreasing and oil removal and purified water washing and drying in sequence; (2) PVD coating treatment: After plasma cleaning of the pretreated stainless steel instruments, PVD tantalum coating is deposited locally on the stainless steel instruments by magnetron sputtering or arc ion plating. (3) One-step electrolytic coloring composite treatment: Prepare an anolyte, use the PVD coated stainless steel instrument as the anode and the stainless steel plate as the cathode for electrochemical treatment, and simultaneously realize the anodizing coloring of the tantalum coating area and the electrochemical polishing of the exposed stainless steel area; wherein, the anolyte contains sulfuric acid with a concentration of 50~200g / L, phosphoric acid with a concentration of 30~150g / L, formic acid with a concentration of 35~180g / L, oxalic acid with a concentration of 20~100g / L, citric acid with a concentration of 5~100g / L, and also contains corrosion inhibitors; (4) Post-treatment: Neutralize, clean and dry the stainless steel instruments after electrolysis.

2. The processing method according to claim 1, characterized in that, In step (1), the abrasive material used for wet sandblasting is alumina or ceramic sand with a particle size of 80~450 mesh, a sandblasting pressure of 0.1~0.6MPa, and a sandblasting distance of 20~300mm.

3. The processing method according to claim 1 or 2, characterized in that, In step (1), the alkaline degreasing agent consists of 5~50g / L sodium hydroxide, 2~30g / L sodium carbonate, 1~25g / L sodium pyrophosphate and 0.5~30g / L sodium dodecylbenzenesulfonate. The degreasing temperature is 30~70℃ and the ultrasonic cleaning time is 5~30min.

4. The processing method according to claim 1, characterized in that, In step (2), the Ar gas inlet flow rate for ion cleaning is 2~30 SCCM, the bias voltage is 200~1000V, the rotating cathode / arc current is 0.5~5A, and the cleaning time is 5~60min.

5. The processing method according to claim 1 or 4, characterized in that, In step (2), the target material for PVD coating is Ta, the Ar inlet gas volume is 10~200SCCM, the bias voltage is 50~400V, the rotating cathode current is 3~20A, the coating temperature is 120~350℃, and the coating time is 60~450min, resulting in a Ta coating with a thickness of 0.1~100μm and a surface roughness of 1.0~2.0μm.

6. The processing method according to claim 5, characterized in that, In the anolyte described in step (3), the concentration of sulfuric acid is 100~200g / L, the concentration of phosphoric acid is 50~100g / L, the concentration of formic acid is 50~150g / L, the concentration of oxalic acid is 30~70g / L, and the concentration of citric acid is 20~100g / L; Preferably, the anolyte further comprises a conductive agent and a thickener, wherein the conductive agent is ethylene glycol with a concentration of 1~60 g / L; and the thickener is glycerol with a concentration of 1~50 mL / L. Preferably, the corrosion inhibitor is sodium silicate with a concentration of 3~25 g / L.

7. The processing method according to claim 6, characterized in that, In step (3), the electrochemical treatment temperature is 10~50℃, the time is 0.5~10min, the oxidation voltage is 1~150V, the thickness of the anodic oxide film generated in the tantalum coating area is 0.2~5μm, and the surface roughness of the exposed stainless steel area is ≤0.2μm.

8. The processing method according to claim 7, characterized in that, In step (3), the tantalum coating area is made to appear in different colors by adjusting the oxidation voltage, including: 8~14V is yellow, 16~24V is golden yellow, 27~32V is purple, 35~45V is magenta, 48~55V is blue, 62~68V is light blue, 97~102V is magenta, and 116~123V is blue-green.

9. The processing method according to claim 1, characterized in that, In step (4), the neutralization is performed using a sodium bicarbonate solution of 10~300g / L or a sodium carbonate solution of 5~200g / L, at a temperature of 20~60℃, and for a time of 0.5~5min.

10. The stainless steel instrument obtained by the processing method according to any one of claims 1-9, characterized in that, The stainless steel instruments are dental medical devices, including surgical forceps, dental tools, or orthodontic brackets. The areas of the stainless steel substrate not covered by the tantalum coating are electrochemically polished smooth surfaces with a surface roughness ≤0.2μm. The areas covered by the tantalum coating have an anodized coloring film. The colored areas meet the requirement of no significant fading after 50 high-temperature and high-pressure tests. The high-temperature and high-pressure test is conducted at a temperature of 132~134℃, a pressure of 0.21~0.22MPa, and a duration of 4min. Furthermore, the corrosion resistance meets the requirement of no corrosion after more than 72 hours of neutral salt spray testing.

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