Preparation method of electroplated hard material dispersion coating enhanced screwdriver head

Abstract

The invention relates to the technical field of hard material electroplated products, in particular to a preparation method of an electroplated hard material dispersion coating enhanced screwdriver bit, which comprises the following steps: S1, preparing a screwdriver bit substrate; s2, treatment before plating; s3, dispersion electroplating; and S4, post-plating treatment. On the basis of a traditional screwdriver head preparation process, hard material micro-powder or fine-particle-size powder with the appropriate particle size is purified, then a nickel or nickel-based alloy plating layer is electroplated on a purified screwdriver head base body through a dispersion electroplating method, and the screwdriver head is prepared. The dispersion plating layer of the bit has the characteristics of strong binding force to a matrix and firm consolidation of reinforced dispersion particles. When the bit works, the friction force between the bit and a screw is large, the occlusal force is strong, the impact resistance is large, the anti-slip effect is remarkable, and the service life is long. And the preparation method provided by the invention is simple in process, safe in production process and suitable for industrial production.

Description

Technical Field

[0001] This application relates to the field of hard material electroplating products, specifically to a method for preparing a bit reinforced with a dispersion coating of electroplated hard material. Background Technology

[0002] Screwdriver bits, as the core working component of screwdrivers, are widely used in many fields such as mechanical assembly, electronic repair, and home renovation. Their performance directly determines the efficiency, quality, and lifespan of screw handling operations. Traditional screwdriver bits often slip during operation due to insufficient friction with the screw groove, damaging the screw, affecting operation, and potentially posing safety hazards to the operator. Simultaneously, the bit tip is prone to wear and chipping under frequent torque and impact loads, resulting in a limited lifespan. Therefore, effectively improving the surface hardness, wear resistance, and engagement ability with screws of screwdriver bits has become a continuously focused area of ​​technological improvement in this field.

[0003] Currently, common techniques for improving the performance of screwdriver bits mainly include overall heat treatment of the bit substrate (such as quenching and tempering) to obtain high hardness, or surface hardening treatment (such as nitriding and carbonitriding) applied to its working parts. In addition, there are methods to coat the surface of the bit with a hard film such as titanium nitride or diamond-like carbon using physical vapor deposition (PVD) or chemical vapor deposition (CVD). However, overall heat treatment may sacrifice the toughness of the material while increasing hardness, increasing the risk of brittle fracture; the depth of the surface hardened layer is limited, and the bonding strength with the substrate is still insufficient under high torsional impact; while PVD / CVD coatings have extremely high hardness, they require large equipment investment, have complex processes, and are costly, and the interfacial bonding strength between the coating and the metal substrate under complex stress conditions remains a technical challenge, limiting their large-scale application in general-purpose screwdriver bit products.

[0004] Therefore, it is of great significance to develop a bit strengthening method that can improve the wear resistance, impact resistance and anti-slip properties of the bit working surface without excessively increasing costs and process complexity. Summary of the Invention

[0005] This application provides a method for preparing a screwdriver bit reinforced with a dispersion coating of electroplated hard material, which improves the wear resistance, impact resistance and anti-slip performance of the working surface of the screwdriver bit without excessively increasing cost and process complexity.

[0006] In a first aspect, the method for preparing a screwdriver bit reinforced with a dispersion coating of electroplated hard material provided in this application adopts the following technical solution: A method for preparing a screwdriver bit reinforced with a dispersion coating of electroplated hard material includes the following steps: S1. Preparation of bit matrix; S2. Pre-plating treatment of the bit substrate, the pre-plating treatment including mechanical leveling, alkaline degreasing, strong acid etching, polishing and dilute acid activation in sequence. S3. Perform dispersion electroplating on the pre-plating treated bit substrate to form a nickel-based or nickel alloy-based composite coating reinforced by dispersion of hard material on its surface; the hard material is diamond and / or cubic boron nitride powder with a particle size of 10-100 micrometers; the process conditions for dispersion electroplating are: plating bath temperature 20-60℃, pH value 3-6, and cathode current density 0.1-15 A / dm2. S4. Perform post-plating treatment on the tool bits that have completed dispersion electroplating, the post-plating treatment including drying.

[0007] By adopting the above technical solution, the entire process from substrate preparation to drying ensures the integrity and controllability of the process. Secondly, the multi-stage pre-plating treatment process, from mechanical leveling to dilute acid activation, included in step S2, can systematically remove oil and oxide layers from the substrate surface and achieve microscopic activation. This provides a clean and highly active bonding interface for subsequent plating layers, ensuring the adhesion between the composite plating layer and the substrate and avoiding the risk of peeling during use. In step S3, by performing dispersion electroplating of diamond and / or cubic boron nitride superhard powder with a particle size of 10-100 micrometers under a specific process window of 20-60℃, pH 3-6, and cathode current density of 0.1-15 A / dm2, these high-hardness, high-wear-resistant particles are uniformly and firmly embedded in the nickel or nickel alloy matrix. Under these process conditions, the metal can achieve dense deposition, thereby effectively "grabbing" the dispersed phase and forming a composite structure with tough metal as support and superhard particles as friction points. This structure allows the final screwdriver bit working surface to simultaneously possess the toughness of the base metal, strong adhesion to the substrate, and high surface hardness and roughness from the ultra-hard microparticles. Therefore, it exhibits better anti-slip properties, high wear resistance, and impact resistance when tightening screws, extending its service life. Furthermore, the entire method is based on a mature electroplating technology framework, with clearly defined process steps and parameter ranges, eliminating the need for complex and expensive equipment, thus ensuring good process stability.

[0008] Optionally, in step S2: The mechanical leveling is carried out by tumbling, polishing or brushing, and in an auxiliary solution composed of one or more of sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, carboxylic acid, fluoride, chloride, aminosulfonic acid and hydrogen peroxide. The processing temperature is 10-50℃ and the processing time is 1-60min. The alkaline degreasing process uses a solution prepared from sodium hydroxide, sodium phosphate, sodium carbonate, and an emulsifier. The treatment temperature is 50-90℃, and the treatment time is 0.1-2h.

[0009] By adopting the above technical solution, sequential treatment of mechanical leveling and alkaline degreasing provides crucial surface pretreatment assurance for the subsequent electroplating process of the bit substrate. First, mechanical leveling, performed in an auxiliary solution prepared with specific chemical reagents, effectively eliminates macroscopic defects and processing marks on the substrate surface. The solution's slight chemical action also preliminarily removes the oxide layer, forming a uniform surface morphology conducive to plating adhesion. Next, under optimized temperature and time parameters, degreasing is performed using an alkaline solution composed of sodium hydroxide, sodium phosphate, sodium carbonate, and an emulsifier. This efficiently removes and emulsifies various oily contaminants remaining on the substrate surface. This ensures that the substrate achieves a high degree of physical cleanliness and an appropriate surface condition before entering the electroplating bath, thus laying a solid foundation for the high-strength and robust bonding of the subsequent "dispersion plating" layer with the substrate.

[0010] Optionally, in step S2: The strong acid etching uses a concentrated solution composed of one or more of sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, carboxylic acid, fluoride, chloride, aminosulfonic acid and hydrogen peroxide, with the addition of a corrosion inhibitor. The treatment temperature is 10-50℃ and the treatment time is 0.1-30 min.

[0011] By employing the above technical solution, the selected strong acid or its combination can effectively dissolve and remove stubborn impurities such as oxide scale, rust layer, and heat-treated oxide film from the surface of the bit substrate, providing a clean and microscopically active metal surface for subsequent processes. This is fundamental to ensuring a strong bond between the coating and the substrate. Secondly, adding a corrosion inhibitor to the concentrated acid solution can inhibit excessive corrosion of the substrate metal (including uniform corrosion and intergranular erosion tendency) while ensuring etching efficiency. This avoids increased surface roughness or hydrogen embrittlement sensitivity caused by over-corrosion, thus maintaining the integrity of the substrate material while cleaning.

[0012] Optionally, in step S2: The polishing is either chemical polishing or electrolytic polishing; The chemical polishing uses a polishing solution composed of one or more of sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, carboxylic acid, fluoride, chloride, sulfamic acid and hydrogen peroxide, with added corrosion inhibitors, and is treated at 10-50℃ for 0.1-30 min. The electropolishing process uses a polishing solution composed of one or more of sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, carboxylic acid, fluoride, chloride, sulfamic acid, and hydrogen peroxide, with added corrosion inhibitors, at 10-50°C and at a rate of 2-20 A / dm³. 2 The current density was processed for 0.1-30 minutes.

[0013] By employing the above technical solution, the polishing solution components (one or more of sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, carboxylic acid, fluoride, chloride, sulfamic acid, and hydrogen peroxide) can effectively dissolve microscopic protrusions on the substrate surface. The added corrosion inhibitors, by inhibiting the uniform dissolution of the metal, promote a more selective dissolution process. This removes residual traces from previous processes while reducing surface roughness, resulting in a brighter, smoother substrate surface. Control of temperature (10-50℃), time (0.1-30 minutes), and electrolytic polishing current density (2-20 A / dm²) ensures the stability and reproducibility of the polishing effect within a wide range of process parameters.

[0014] Optionally, in step S2: The dilute acid activation uses a dilute solution composed of one or more of sulfuric acid, hydrochloric acid, nitric acid and aminosulfonic acid, with a treatment temperature of 0-50℃ and a treatment time of 0.1-10 min.

[0015] By employing the above-mentioned technical solution, a dilute acid solution is used to perform a gentle yet efficient chemical activation of the bit substrate. This effectively dissolves and removes the extremely thin oxide film and impurities that may remain or reform after previous processes, exposing a highly fresh, clean, and electrochemically active metal crystal structure on the substrate surface. This process not only lays a crucial clean base for subsequent dispersion electroplating, ensuring a strong and tough metallurgical bond between the hard material dispersion coating and the bit substrate, but also avoids the risk of substrate over-corrosion or hydrogen embrittlement that may be caused by strong acids due to the use of a dilute acid system and a limited treatment time.

[0016] Optionally, in step S3: The electroplating solution used for dispersion electroplating has a main salt composed of one or more substances such as sulfate, hydrochloride, hypophosphite, aminosulfonate, tungstate, and molybdate of the electroplated metal. The electroplating solution also contains buffers, wetting agents, leveling agents or brighteners, and anodic activators.

[0017] By adopting the above technical solutions, the composition of the electroplating solution provides a crucial solution environment guarantee for achieving high-quality dispersion coatings. The main salt system provides the metal ion source required for the formation of nickel or nickel-based alloy coatings, and its combination selection helps to control the coating deposition behavior and basic mechanical properties. The introduction of buffers effectively maintains the stability of the pH value during electroplating, which is a necessary condition to ensure that metal ions are deposited uniformly at the expected rate and to obtain a dense coating. Wetting agents improve the coverage and penetration ability of the complex geometry of the tool bits by reducing the surface tension of the plating solution, reducing the possibility of incomplete or loose coatings caused by surface gas adhesion or uneven liquid flow, thus ensuring the integrity of the coating, especially on critical working surfaces such as trenches. Leveling agents or brighteners exert an adsorption effect on the cathode surface, smoothing microscopic peaks and valleys and refining coating grains. This not only helps to obtain a smooth coating surface but also directly enhances the density, hardness, and corrosion resistance of the coating itself. The anodic activator effectively inhibits the passivation of the anode, ensuring the continuous and uniform dissolution of the anode metal, thereby maintaining the long-term stability of the metal ion concentration in the plating solution and ensuring the reproducibility of the process and the stability of production.

[0018] Optionally, in step S3: The matrix metal of the composite coating is nickel or a nickel-based alloy, wherein the nickel-based alloy is an alloy formed by nickel and one or more elements selected from cobalt, tungsten, molybdenum, iron, and phosphorus. Furthermore, the anode used in electroplating is a flat, block, or spherical electrode made of nickel, cobalt, nickel-cobalt alloy, or iron.

[0019] By adopting the above technical solution, nickel or a nickel-based alloy composed of nickel and one or more elements selected from cobalt, tungsten, molybdenum, iron, and phosphorus is selected as the matrix metal for the composite coating, laying the material foundation for the coating system. The nickel matrix itself possesses good toughness, ductility, and excellent electrochemical bonding ability with the steel bit substrate. The introduction of alloying elements such as cobalt and tungsten can improve the hardness, wear resistance, thermal stability, and fatigue strength of the coating through solid solution strengthening and the formation of intermetallic compounds. This allows the coating to solidify hard material particles while possessing a strong and tough substrate capable of withstanding severe torsional and impact loads. In conjunction with this, using an anode (such as nickel, cobalt, nickel-cobalt alloy, or iron) that matches the composition of the target deposited metal is crucial for maintaining the stability of the electroplating process. A matched anode ensures that metal ions continuously and uniformly dissolve and replenish the plating solution at the expected valence state and rate, effectively avoiding problems such as impurity ion contamination, anode passivation, or decreased current efficiency caused by inappropriate anode composition. The choice of various anode shapes, such as flat plates, blocks, or spheres, provides flexibility for tank design and current distribution optimization to adapt to different production equipment.

[0020] Optionally, in step S3: The dispersion electroplating specifically includes the following steps: air plating, sand plating, thickening plating, and bright plating. The cathode current density for the empty plating is 0.5-5 A / dm. 2 ; When the sand plating process employs the buried sand method, the cathode current density is 0.1-0.5 A / dm². 2 When using the sand-falling method, the cathode current density is 0.3-1.5 A / dm³. 2 ; The cathode current density of the thickened plating is 0.5-15 A / dm. 2 ; The cathode current density of the bright plating is 1-10 A / dm. 2 .

[0021] By adopting the above technical solution, the dry plating step is completed at 0.5-5 A / dm. 2 The process is carried out at a specific current density, which enables the rapid formation of a thin and dense pure metal underlayer on a clean and activated substrate. This underlayer not only effectively prevents corrosion of the substrate in subsequent plating solutions, but more importantly, it provides an interface with excellent conductivity and high bonding strength for the subsequent adhesion of ultra-hard particles. This is a key prerequisite for achieving a strong metallurgical bond between the coating and the substrate.

[0022] The subsequent sandblasting step varies depending on the physical sandblasting method (0.1-0.5 A / dm for the buried sandblasting method). 2 The sand drop method uses 0.3-1.5 A / dm. 2 The relatively low cathode current density creates a mild electrocrystallization environment, reducing the intensity of hydrogen evolution at the cathode surface. This effectively prevents the scouring effect on adsorbed or partially embedded ultrahard particles caused by violent hydrogen escape, thus preventing particle detachment. Furthermore, the moderate metal deposition rate allows sufficient time for metal ions to deposit orderly around and beneath the particles, initially but firmly anchoring them to the coating surface. This achieves uniform dispersion and initial mechanical intercalation of the ultrahard particles within the coating.

[0023] The thickening plating step is at 0.5-15 A / dm. 2 The process is conducted over a wide current density range, enabling rapid and high-volume metal deposition on a pre-fixed microparticle coating. The higher current density increases the metal deposition rate and coating growth efficiency, thus completely encapsulating and deeply embedding the previously anchored microparticles within the continuously thickening metal matrix. This process enhances the mechanical locking effect of the coating on the microparticles, making them less susceptible to extraction under significant shear forces, while simultaneously rapidly building the coating's bulk thickness and macroscopic strength.

[0024] The final brightening process, at 1-10 A / dm2 The process is completed at a specific current density, resulting in the modification and strengthening of the outermost surface of the coating. Under these conditions, the deposited metal layer crystals are more refined and densely packed, thus forming a dense, smooth, and glossy pure metal capping layer on the surface of the composite coating, further enhancing its overall wear resistance and durability.

[0025] Optionally, in step S3: The empty plating and / or thickening plating steps of the dispersion electroplating optimize the initial current distribution by configuring the relative geometric positions of the cathode and anode, and optimize the secondary current distribution by adding leveling agents or brighteners to the electroplating solution, thereby making the composite coating uniform in thickness and dense in crystal.

[0026] By employing the above technical solution, in the empty plating and thickening plating stages of dispersion electroplating, the initial current distribution is optimized by configuring the relative geometric positions of the anode and cathode. This effectively improves the uniformity of the electric field between the anode and various parts of the complex contour surface of the bit, laying the foundation for obtaining a uniformly thick coating. Simultaneously, the secondary current distribution is optimized by adding leveling agents or brighteners. These additives, through selective adsorption on the cathode surface, can suppress the metal deposition rate at microscopic protrusions, thereby further enhancing the uniformity of coating thickness at the microscale (i.e., leveling effect) and improving cathode polarization. This promotes the formation of finer grains during metal ion deposition, resulting in a dense and crystalline coating structure. This coating, possessing both uniformity and microscopic density, has a more rational internal stress distribution, a stronger bond with the substrate, and can more effectively encapsulate and consolidate the dispersed phase of hard materials.

[0027] Optionally, in step S4: The drying is carried out in an oven at a temperature of 100-200℃ for 1-5 hours, and hydrogen removal is performed simultaneously during the process.

[0028] By adopting the above technical solution, hydrogen elements that cause hydrogen embrittlement are effectively removed, reducing the risk of delayed fracture of the bit under high torque loads. Thus, while giving the bit surface coating enhanced properties, it also prevents brittle failure originating from within when the product is subjected to impact or cyclic torsional loads.

[0029] In summary, this application includes at least one of the following beneficial technical effects: 1. A composite coating, consisting of nickel or nickel alloy as the matrix and hard microparticles as the dispersed phase, is constructed on the surface of the screwdriver bit substrate using a dispersion electroplating process. This coating, through an optimized electroplating process, achieves a strong metallurgical bond between the metal matrix and the substrate, while simultaneously embedding the ultra-hard microparticles firmly within it, forming a microscopically reinforced structure. During operation, the ultra-hard microparticles on the coating surface act as hard protrusions, increasing friction and mechanical engagement with the screw groove, effectively preventing slippage; the metal matrix provides tough support, buffering localized impact stress and preventing coating peeling or chipping, thereby synergistically improving the screwdriver bit's wear resistance, impact resistance, and service life. 2. By employing a scientifically sound anode and cathode configuration and improving cathode polarization conditions, high uniformity of plating in both the base layer and composite coating is achieved. The coating exhibits fine and dense crystal structure, strong adhesion to the substrate, and high bonding strength to diamond particles. During operation, the screwdriver bit demonstrates high friction with screws, strong engagement force, high impact resistance, significant anti-slip effect, and long service life. Furthermore, the provided preparation method is simple, safe in production, and suitable for industrial production. Detailed Implementation

[0030] Example 1 A method for preparing a screwdriver bit reinforced with a dispersion coating of electroplated hard material includes the following steps: S1. Preparation of bit base: Standard PH2 cross-head bit base is made of SCM440 alloy steel through machining. S2. Pre-plating treatment: S21. Mechanical leveling: Place the bit base and ceramic abrasive together in a tumbler, add a solution containing 10% sulfuric acid (volume fraction) as an auxiliary leveling medium, and tumble grind at 30°C for 15 minutes. After completion, rinse thoroughly with clean water; S22. Alkaline degreasing: Immerse the bit in an alkaline degreasing solution containing 50 g / L sodium hydroxide and 30 g / L sodium phosphate, and ultrasonically clean it at 60°C for 1 hour. After completion, thoroughly clean it with hot water above 60°C and running cold water. S23. Strong acid etching: Immerse the bit in a 20% hydrochloric acid (mass fraction) solution and add 0.5 g / L hexamethylenetetramine as a corrosion inhibitor. Treat at 25°C for 5 minutes to remove surface oxide scale and rust. Rinse with cold water after completion. S24. Electrolytic polishing: Use a phosphoric acid-sulfuric acid system electrolytic polishing solution (phosphoric acid: sulfuric acid = 3:1, volume ratio), with the screwdriver bit as the anode (non-working parts need to be insulated) and the stainless steel plate as the cathode. Electrolytic polish for 3 minutes at a current density of 10 A / dm² and a temperature of 40℃ to obtain a bright and smooth surface. Rinse with cold water after completion. S25. Dilute acid activation: Immerse the bit in a 10% sulfuric acid (volume fraction) solution at room temperature (about 25°C) for 2 minutes to remove the very thin oxide film and activate the surface. After completion, rinse quickly with deionized water and immediately transfer to the electroplating process. S3, Dispersion electroplating: Uses purified synthetic diamond micro powder with an average particle size (D50) of 40 μm; Electrolyte composition: Nickel sulfamate: 400 g / L, boric acid (buffer): 40 g / L, nickel chloride (anodic activator): 15 g / L, sodium dodecyl sulfate (wetting agent): 0.05 g / L, sodium saccharin (primary brightener): 1 g / L, butynediol (secondary brightener): 0.5 g / L; A special electroplating tank is used. The cathode is a clamp that can hold multiple bits in parallel and rotate at a uniform speed. The anode is a titanium basket loaded with electrolytic nickel balls. The anode and cathode are placed in parallel and symmetrically with a distance of 15 cm between them. S31. Empty plating: Immerse the activated bit into the above plating solution without diamond powder, and electroplate for 5 minutes under the conditions of cathode current density 2A / dm², temperature 55℃, and pH=4.0. S32. Top-coating (drop-coating method): Add 30 g / L of diamond micro powder to the plating solution and continuously stir mechanically to ensure uniform suspension of the microparticles. Use a cathode current density of 1 A / dm² and electroplating at 55℃ and pH=4.0 for 30 minutes. S33, Thickening Plating: Remove excess hard material suspension, increase the cathode current density to 5 A / dm², and continue electroplating for 120 minutes at 55℃ and pH=4.0 to firmly encapsulate the adsorbed diamond particles and thicken the plating to about 80 μm. S34, Bright plating: Electroplating for 10 minutes at a cathode current density of 3 A / dm², a temperature of 55℃, and a pH of 4.0; S4. Post-plating treatment: After electroplating, remove the bit, clean it with deionized water, and then put it into a 180℃ forced-air drying oven for 2 hours for drying and hydrogen removal.

[0031] Example 2 differs from Example 1 in that the diamond powder is replaced with cubic boron nitride powder with an average particle size of 20 μm.

[0032] Comparative Example 1 differs from Example 1 in that the mechanical leveling step S21 is omitted, and after the bit base is machined, the alkaline degreasing step S22 is performed directly.

[0033] Comparative Example 2 differs from Example 1 in that the process parameters for degreasing with S22 alkaline solution are changed to a temperature of 40°C and a time of 0.05 hours (3 minutes).

[0034] Comparative Example 3 differs from Example 1 in that the solution used for S23 strong acid etching was replaced with 5% dilute hydrochloric acid, and no corrosion inhibitor was added, while the treatment time remained at 5 minutes.

[0035] Comparative Example 4 differs from Example 1 in that the S24 electropolishing step is omitted, and after the S23 strong acid etching and cleaning, the S25 dilute acid activation is performed directly.

[0036] Comparative Example 5 differs from Example 1 in that the S25 dilute acid activation step is omitted, and after S24 electrolytic polishing and cleaning, it directly enters the S3 dispersion electroplating empty plating stage.

[0037] Comparative Example 6 differs from Example 1 in that the electroplating solution for S3 dispersion electroplating is changed, and a basic Watt nickel plating solution is used: nickel sulfate 250 g / L, nickel chloride 50 g / L, boric acid 40 g / L, without the addition of sodium dodecyl sulfate, sodium saccharin, and butynediol.

[0038] Comparative Example 7 differs from Example 1 in that the matrix metal of S3 dispersion electroplating is changed, cobalt is used as the plating metal, and the main salt of the electroplating solution is changed to cobalt chloride.

[0039] Comparative Example 8 differs from Example 1 in that, in the S3 dispersion electroplating, the bright plating step is omitted, and after the thick plating is completed, the bit is directly removed for cleaning and post-plating treatment.

[0040] Comparative Example 9 differs from Example 1 in that, in the empty plating and thickening plating stages of S3 dispersion electroplating, a non-parallel anode and cathode configuration is used (the anode nickel ball basket is placed on one side of the electroplating tank, and the bit clamp is placed on the other side), and no brighteners or leveling agents (i.e., sodium saccharin and butynediol) are added to the electroplating solution.

[0041] Comparative Example 10 differs from Example 1 in that, in the empty plating and thickening plating stages of S3 dispersion electroplating, a non-parallel anode and cathode configuration is used (the anode nickel ball basket is placed on one side of the electroplating tank, and the bit clamp is placed on the other side).

[0042] Comparative Example 11 differs from Example 1 in that no brightener or leveling agent is added to the electroplating solution during the empty plating and thickening plating stages of S3 dispersion electroplating.

[0043] Detection example Wear resistance test: Referring to the improved method of GB / T 12444-2006 "Metallic Materials Wear Test Method - Ring-block Wear Test", the bit tip was fixed and rubbed against a friction disc with standard hardness (HRC 50) at a constant pressure (50 N) and rotation speed (200 rpm); Wear mass loss (mg): The mass loss of the bit tip after 60 minutes of rubbing was recorded. The smaller the loss, the better the wear resistance. Anti-slip torque test: Referring to the general testing standards of the screwdriver industry, the bit is loaded into a torque tester and engaged with the cross groove of a standard screw (hardness HRC 38-42). The tester drives the bit to rotate and measures the maximum torque value (N·m) when the screw groove begins to produce visible plastic deformation (i.e. slippage). The higher this torque value, the stronger the engagement ability between the bit and the screw and the better the anti-slip performance. Coating adhesion test: The worse result of the two tests is used as the final adhesion rating of the sample; File test: Use a coarse-toothed flat file to file the edge of the coating on the bit shank in one direction at a 45° angle to the coating surface; observe whether the coating peels or flakes off; rating: no peeling is "excellent"; slight peeling but no flakes is "good"; obvious flakes are "poor"; Thermal shock test: Place the bit in a muffle furnace preheated to 250°C and hold for 30 minutes, then quickly immerse it in room temperature (25°C) cold water for rapid cooling; repeat this cycle 3 times, then observe the coating surface with a 10x magnifying glass to check for blistering, cracking, or peeling. Rating: No defects are "Excellent"; minor cracks but no peeling are "Good"; blistering or peeling is "Poor". The specific test results are shown in Table 1.

[0044] Table 1

[0045] The performance test data from Examples 1 and Comparative Examples 1-5 show that the integrity of the pre-plating treatment is crucial. The lack of mechanical leveling (Comparative Example 1), incomplete degreasing (Comparative Example 2), or omission of activation (Comparative Example 5) all resulted in a significant decrease in coating adhesion to the "poor" level, and severely weakened wear resistance and anti-slip ability. Although insufficient strong acid etching concentration (Comparative Example 3) and omission of polishing (Comparative Example 4) did not directly lead to complete failure of adhesion, they caused a significant downward trend in wear resistance and anti-slip performance, indicating that these steps are necessary to obtain a high-quality, high-adhesion starting surface.

[0046] The performance test data from Examples 1 and Comparative Examples 6-8 show that the formulation and process control of dispersion electroplating are key to performance. Using ordinary plating solution without specific additives (Comparative Example 6) results in rough crystallization of the coating and weak encapsulation of ultra-hard particles, manifested as a sharp decrease in wear resistance and a weakening of anti-slip ability. Replacing the matrix metal with cobalt (Comparative Example 7) results in slightly inferior overall performance compared to nickel-based coatings. The elimination of bright plating (Comparative Example 8) has little impact on adhesion, but slightly reduces wear resistance and surface smoothness, indicating that this step is an optimization measure to further improve performance.

[0047] The performance test data from Examples 1 and Comparative Examples 9-11 show that simultaneously optimizing geometric and electrochemical factors during the electroplating process has a synergistic effect on obtaining high-performance composite coatings. Optimizing only geometric factors (Comparative Example 11) or only electrochemical factors (Comparative Example 10) can achieve much better performance than not optimizing either (Comparative Example 9), but neither reaches the optimal level of simultaneous optimization of both (Example 1). In particular, when both are absent (Comparative Example 9), the current distribution is extremely uneven, resulting in locally thin and porous coatings, and even particle detachment. All performance characteristics show the worst trend. This proves that current distribution optimization is the key to ensuring uniform, dense, and high-performance coatings, rather than a dispensable conventional choice.

[0048] The performance test data from Examples 1-2 show that replacing the hard material with cubic boron nitride (CBN) micro powder does not significantly alter the performance, demonstrating the equivalence and versatility of the hard material cubic boron nitride (CBN) micro powder.

[0049] Please note that the technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments have been described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification. The above embodiments only illustrate several implementation methods of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for preparing a screwdriver bit reinforced with a dispersion coating of electroplated hard material, characterized in that, Includes the following steps: S1. Preparation of bit matrix; S2. Pre-plating treatment of the bit substrate, the pre-plating treatment including mechanical leveling, alkaline degreasing, strong acid etching, polishing and dilute acid activation in sequence. S3. Perform dispersion electroplating on the pre-plating treated bit substrate to form a nickel-based or nickel alloy-based composite coating reinforced by dispersion of hard materials on its surface. The hard material is diamond and / or cubic boron nitride powder with a particle size of 10-100 micrometers; The process conditions for the dispersion electroplating are as follows: plating bath temperature 20-60℃, pH value 3-6, and cathode current density 0.1-15A / dm³. 2 ; S4. Perform post-plating treatment on the tool bits that have completed dispersion electroplating, the post-plating treatment including drying.

2. The method for preparing a screwdriver bit reinforced with a dispersion coating of electroplated hard material according to claim 1, characterized in that, In step S2: The mechanical leveling is carried out by tumbling, polishing or brushing, and in an auxiliary solution composed of one or more of sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, carboxylic acid, fluoride, chloride, aminosulfonic acid and hydrogen peroxide. The processing temperature is 10-50℃ and the processing time is 1-60min. The alkaline degreasing process uses a solution prepared from sodium hydroxide, sodium phosphate, sodium carbonate, and an emulsifier. The treatment temperature is 50-90℃, and the treatment time is 0.1-2h.

3. The method for preparing a screwdriver bit reinforced with a dispersion coating of electroplated hard material according to claim 1, characterized in that, In step S2: The strong acid etching uses a concentrated solution composed of one or more of sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, carboxylic acid, fluoride, chloride, aminosulfonic acid and hydrogen peroxide, with the addition of a corrosion inhibitor. The treatment temperature is 10-50℃ and the treatment time is 0.1-30 min.

4. The method for preparing a screwdriver bit reinforced with a dispersion coating of electroplated hard material according to claim 1, characterized in that, In step S2: The polishing is either chemical polishing or electrolytic polishing; The chemical polishing uses a polishing solution composed of one or more of sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, carboxylic acid, fluoride, chloride, sulfamic acid and hydrogen peroxide, with added corrosion inhibitors, and is treated at 10-50℃ for 0.1-30 min. The electropolishing process uses a polishing solution composed of one or more of sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, carboxylic acid, fluoride, chloride, sulfamic acid, and hydrogen peroxide, with added corrosion inhibitors, at 10-50°C and at a rate of 2-20 A / dm³. 2 The current density was processed for 0.1-30 minutes.

5. The method for preparing a screwdriver bit reinforced with a dispersion coating of electroplated hard material according to claim 1, characterized in that, In step S2: The dilute acid activation uses a dilute solution composed of one or more of sulfuric acid, hydrochloric acid, nitric acid and aminosulfonic acid, with a treatment temperature of 0-50℃ and a treatment time of 0.1-10 min.

6. The method for preparing a screwdriver bit reinforced with a dispersion coating of electroplated hard material according to claim 1, characterized in that, In step S3: The electroplating solution used for dispersion electroplating has a main salt composed of one or more substances such as sulfate, hydrochloride, hypophosphite, aminosulfonate, tungstate, and molybdate of the electroplated metal. The electroplating solution also contains buffers, wetting agents, leveling agents or brighteners, and anodic activators.

7. The method for preparing a screwdriver bit reinforced with a dispersion coating of electroplated hard material according to claim 1, characterized in that, In step S3: The matrix metal of the composite coating is nickel or a nickel-based alloy, wherein the nickel-based alloy is an alloy formed by nickel and one or more elements selected from cobalt, tungsten, molybdenum, iron, and phosphorus. Furthermore, the anode used in electroplating is a flat, block, or spherical electrode made of nickel, cobalt, nickel-cobalt alloy, or iron.

8. The method for preparing a screwdriver bit reinforced with a dispersion coating of electroplated hard material according to claim 1, characterized in that, In step S3: The dispersion electroplating specifically includes the following steps: air plating, sand plating, thickening plating, and bright plating. The cathode current density for the empty plating is 0.5-5 A / dm. 2 ; When the sand plating process employs the buried sand method, the cathode current density is 0.1-0.5 A / dm². 2 When using the sand-falling method, the cathode current density is 0.3-1.5 A / dm³. 2 ; The cathode current density of the thickened plating is 0.5-15 A / dm. 2 ; The cathode current density of the bright plating is 1-10 A / dm. 2 .

9. The method for preparing a screwdriver bit reinforced with a dispersion coating of electroplated hard material according to claim 1, characterized in that, In step S3: The empty plating and / or thickening plating steps of the dispersion electroplating optimize the initial current distribution by configuring the relative geometric positions of the cathode and anode, and optimize the secondary current distribution by adding leveling agents or brighteners to the electroplating solution, thereby making the composite coating uniform in thickness and dense in crystal.

10. The method for preparing a screwdriver bit reinforced with a dispersion coating of electroplated hard material according to claim 1, characterized in that, In step S4: The drying is carried out in an oven at a temperature of 100-200℃ for 1-5 hours, and hydrogen removal is performed simultaneously during the process.

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