A method for preparing composite coatings on small workpieces based on substrate coating and subsequent molding

Abstract

This invention discloses a method for preparing a composite coating on small workpieces based on substrate plating followed by forming, belonging to the field of material surface treatment technology. The method includes sequentially executed steps of substrate preparation, overall plating, precision forming, and post-processing. The substrate preparation step provides a large-size planar substrate much larger than the target workpiece. The overall plating step prepares a uniform metal-based composite coating containing second-phase reinforcing particles on the substrate surface. The precision forming step processes the plating substrate into multiple target small workpieces. This invention abandons the traditional process of forming first and then plating, fundamentally solving the problems of floating and displacement, uneven particle distribution, low clamping efficiency, and large obstruction by fixtures during the plating of small workpieces. The resulting coating exhibits good uniformity and enables efficient mass production of small workpieces.

Description

Technical Field

[0001] This invention relates to the field of material surface treatment technology, and in particular to a method for preparing a composite coating on small workpieces based on substrate coating followed by molding. Background Technology

[0002] In fields such as small engines and precision transmission equipment, small and even ultra-small metal friction-increasing / friction-reducing gaskets, seals and other workpieces are widely used. Their surfaces need to be coated with a nickel-phosphorus / reinforcing particle chemical composite coating to meet the requirements of wear resistance, friction enhancement and corrosion resistance.

[0003] In existing technologies, the preparation of composite coatings for such workpieces typically employs a "form-then-coat" process, where a small workpiece in its final form is first machined, then clamped in a fixture and immersed in a chemical composite plating solution for plating. This method has the following inherent drawbacks: First, the small size and light weight of the workpiece make it prone to floating, rotating, or sticking together under the buoyancy and bubble disturbance of the plating solution, making it impossible to maintain a stable immersion posture and resulting in uneven coating thickness. Second, the unstable workpiece posture leads to significant differences in the probability of collision and adsorption of reinforcing particles on the workpiece surface, easily resulting in particle enrichment on one side and deficiency on the other, severely affecting the uniformity and batch consistency of the coating performance. Third, clamping the tiny workpieces requires the design of precise micro-fixtures, making the clamping operation cumbersome, with small batch sizes and extremely low production efficiency. Fourth, the shielding area of ​​the fixture contact points accounts for a large proportion of the total workpiece area, severely affecting the effective plating area and coating functionality, resulting in a low finished product yield. Therefore, there is an urgent need for an efficient and stable preparation method that can ensure uniform composite coatings for ultra-small workpieces. Summary of the Invention

[0004] To address the technical problems existing in the composite plating of small workpieces in current technologies, such as workpiece floating and displacement, uneven distribution of reinforcing particles, low clamping efficiency, and large proportion of the area obscured by the fixture, this invention provides a method for preparing a composite coating on small workpieces based on substrate plating followed by forming. This method abandons the traditional process of forming first and then plating, and adopts a reverse process of "first overall plating, then precision segmentation," thus solving the aforementioned technical problems and enabling efficient mass production of small workpieces.

[0005] The technical solution adopted in this invention, a method for preparing a composite coating on a small workpiece based on substrate plating followed by molding, is as follows: A method for preparing a composite coating on a small workpiece based on substrate plating followed by molding includes the following steps: S1. Substrate preparation: Provide a large-size planar substrate with dimensions much larger than the target small workpiece, wherein the material of the substrate is matched with the matrix material of the target small workpiece; S2. Overall plating: The large-size planar substrate is subjected to overall chemical composite plating treatment to prepare a metal-based composite coating with uniformly distributed second-phase reinforcing particles on the surface of the substrate to be processed. S3. Precision forming: The substrate with a composite coating is formed and divided by precision machining to obtain multiple small workpiece blanks with the same size and shape as the target. S4. Post-processing: Perform post-processing on the small workpiece blank to obtain a finished small workpiece with a uniform composite coating on the surface.

[0006] A further improvement of the technical solution of the present invention is that: in step S1, the large-size planar substrate is a thin sheet or plate-shaped metal substrate, and the material of the substrate is the same as the base material of the target small workpiece.

[0007] A further improvement of the technical solution of the present invention is that: in step S2, the overall chemical composite plating process uses an adjustable clamping fixture to fix the large-size planar substrate in a vertical position and immerse it in the chemical composite plating solution for plating, so that the plating thickness on both sides of the substrate and the distribution of the second phase reinforcing particles are uniform.

[0008] A further improvement of the technical solution of the present invention is that: in step S2, the thickness of the prepared metal-based composite coating is 10μm-30μm, and the volume fraction of the second phase reinforcing particles in the coating is 5%-50%.

[0009] A further improvement of the technical solution of the present invention is that: in step S3, the precision processing method is any one of wire cutting, laser cutting, precision stamping, and photochemical etching, and the width of the heat-affected zone of the substrate coating is ≤0.5mm during the processing.

[0010] A further improvement of the technical solution of the present invention is that: in step S4, the post-processing of the finished product includes at least one of ultrasonic cleaning, deburring, and vacuum drying.

[0011] The technological advancements achieved by this invention due to the adoption of the above technical solutions are as follows: This invention uses a large-size substrate as the plating carrier, which is easy to clamp and fix, avoiding the problems of small workpieces floating, shifting, and sticking in the plating solution. At the same time, it reduces the proportion of the area covered by the hanger, eliminates plating defects caused by the hanging point covering, and increases the effective plating area.

[0012] This invention applies plating to large-size planar substrates, making process parameters easier to control stably. It can achieve a high degree of uniformity in plating thickness and second-phase particle distribution. This uniformity is directly "inherited" to each finished workpiece through subsequent segmentation processing, solving the problem of uneven particle distribution in traditional processes and ensuring the uniformity of workpiece performance and batch consistency.

[0013] This invention enables efficient mass production: a single plating process can produce a large area of ​​plating substrate, and dozens or even hundreds of qualified small workpieces can be obtained simultaneously through one forming process, which greatly simplifies the clamping and plating process, and improves production efficiency by dozens of times compared with traditional processes, thus meeting the needs of industrialized mass production.

[0014] This invention is not limited by the final workpiece shape. Whether it is a round, square, or irregularly shaped workpiece, the preparation can be completed simply by adjusting the forming process or mold. There is no need to redesign the fixture, and the process adaptability is strong. At the same time, it is compatible with a variety of chemical composite coating systems and has a wide range of applications.

[0015] This invention avoids the scrapping of workpieces caused by the obstruction of hanging points and uneven coating in traditional processes. Workpieces divided from the same substrate have highly consistent performance, and the material utilization rate and finished product qualification rate are greatly improved. Attached Figure Description

[0016] Figure 1 This is a process flow diagram of a method for preparing a composite coating on a small workpiece based on substrate coating and subsequent molding according to the present invention. Figure 2 This is a schematic flowchart of a method for preparing a composite coating on a small workpiece based on substrate coating and subsequent molding according to the present invention. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings. In the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessarily obscuring the concept of this invention. Example 1

[0018] like Figure 1 and Figure 2 As shown in the figure, this embodiment discloses a method for preparing a composite coating of a small workpiece based on substrate plating and forming, which is used to prepare an eccentric hole friction-increasing gasket for an outboard motor engine. The target finished small workpiece is a 65Mn spring steel gasket with a diameter of 20mm and a thickness of 0.2mm, and a nickel-phosphorus-diamond composite coating needs to be prepared on the surface.

[0019] The specific preparation steps are as follows: S1. Substrate preparation: Select three 100mm×100mm×0.2mm 65Mn spring steel strips as large-size planar substrates. The substrate material is completely consistent with the substrate material of the target workpiece. A single substrate is divided into more than 16 target workpieces at one time.

[0020] S2. Overall plating: Using a special adjustable clamping fixture with a multi-angle adjustable clamping structure, three spring steel strips are suspended and fixed in parallel and vertically. After degreasing, derusting, and activation pretreatment in sequence, they are immersed in nickel-phosphorus-diamond chemical composite plating solution and plated at a constant temperature of 85℃ for 0.5 hours. A nickel-phosphorus-diamond composite coating with a thickness of about 10μm and uniform diamond particle distribution is prepared on both sides of the substrate. The surface distribution density of diamond particles in the coating is about 25%. During the plating process, the substrate maintains a vertical and stable posture without displacement or shaking. The coating thickness deviation is ≤±1μm, and the particle distribution on both sides is uniform.

[0021] S3. Precision forming: After the plated substrate is removed, cleaned and dried, a precision laser cutting machine is used to cut circular gasket blanks with the target size and eccentric hole structure on the plated substrate in an array arrangement. During the cutting process, the width of the heat-affected zone of the plating layer is ≤0.05mm, the cut is flat, and there are no problems with the plating layer curling or falling off.

[0022] S4. Post-processing: The cut gasket blank is placed in anhydrous ethanol for ultrasonic cleaning for 5 minutes to remove cutting residue. Then, the cut burrs are treated with a precision deburring tool. After vacuum drying at 80℃, the finished friction-enhancing gasket with a uniform nickel-phosphorus-diamond composite coating is obtained.

[0023] The performance of the finished gaskets prepared in this embodiment was tested. The coating thickness deviation of the same batch of gaskets was ≤±1.5μm, the diamond particle distribution uniformity deviation was ≤5%, there were no coating masking defects, and the finished product qualification rate reached 100%. Compared with the traditional process of forming first and then coating, the production efficiency was increased by more than 40 times. Example 2

[0024] In this embodiment, the target small workpiece is a square anti-friction pad for a micro transmission system, with dimensions of 10mm×10mm×0.5mm. The base material is 304 stainless steel, and a nickel-phosphorus-silicon carbide composite coating needs to be prepared on the surface.

[0025] The specific preparation steps are as follows: S1. Substrate Preparation: A 150mm×150mm×0.5mm 304 stainless steel plate was selected as the large-size planar substrate.

[0026] S2. The substrate is vertically fixed by an adjustable clamping fixture for overall plating, and a nickel-phosphorus-silicon carbide composite coating with a thickness of 15μm and a silicon carbide particle volume fraction of 18% is prepared by plating.

[0027] S3. Precision forming adopts precision stamping process to form square gasket blanks arranged in an array in one stamping.

[0028] S4. The finished product is obtained after ultrasonic cleaning, deburring, and drying.

[0029] In the above embodiments, a method for preparing a composite coating on small workpieces based on substrate plating and subsequent molding is provided. This invention uses a large-size substrate as the plating carrier, which is easy to clamp and fix, avoiding the problems of small workpieces floating, shifting, and sticking in the plating solution. Simultaneously, it reduces the proportion of the area obscured by the hanger, eliminates plating defects caused by hanger obstruction, and increases the effective plating area. This invention applies plating to a large-size planar substrate, making process parameters easier to control stably, achieving a high degree of uniformity in coating thickness and second-phase particle distribution. This uniformity is directly "inherited" to each finished workpiece through subsequent segmentation processing, solving the problem of uneven particle distribution in traditional processes and ensuring the uniformity of workpiece performance and batch consistency. This invention achieves high-efficiency batch processing. Mass production: A single plating process can produce large areas of plating substrate, and dozens or even hundreds of qualified small workpieces can be obtained simultaneously through one forming process, greatly simplifying the clamping and plating procedures. The production efficiency is dozens of times higher than that of traditional processes, making it suitable for industrial mass production needs. This invention is not limited by the shape of the final workpiece. Whether it is a round, square, or irregularly shaped workpiece, only the forming process program or mold needs to be adjusted to complete the preparation. There is no need to redesign the fixture, and the process adaptability is strong. At the same time, it is compatible with a variety of chemical composite coating systems, and has a wide range of applications. This invention avoids the workpiece scrap caused by the obstruction of hanging points and uneven coating in traditional processes. The performance of workpieces divided from the same substrate is highly consistent, and the material utilization rate and the finished product qualification rate are greatly improved.

[0030] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the concept and scope of the present invention. Various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the inventive concept should fall within the protection scope of the present invention. All technical contents for which protection is sought in this invention are fully described in the claims.

Claims

1. A method for preparing a composite coating on a small workpiece after forming based on plating a base material, characterized by, Includes the following steps: S1. Substrate preparation: Provide a large-size planar substrate with dimensions much larger than the target small workpiece, wherein the material of the substrate is matched with the matrix material of the target small workpiece; S2. Overall plating: The large-size planar substrate is subjected to overall chemical composite plating treatment to prepare a metal-based composite coating with uniformly distributed second-phase reinforcing particles on the surface of the substrate to be processed. S3. Precision forming: The substrate with a composite coating is formed and divided by precision machining to obtain multiple small workpiece blanks with the same size and shape as the target. S4. Post-processing: Perform post-processing on the small workpiece blank to obtain a finished small workpiece with a uniform composite coating on the surface.

2. The method according to claim 1, wherein the method is characterized by: In step S1, the large-size planar substrate is a sheet-like or plate-like metal substrate, and the material of the substrate is the same as the base material of the target small workpiece.

3. The method according to claim 1, wherein the method is characterized by: In step S2, the overall chemical composite plating process uses an adjustable clamping fixture to fix the large-size planar substrate in a vertical position and immerse it in the chemical composite plating solution for plating, so that the plating thickness on both sides of the substrate and the distribution of the second phase reinforcing particles are uniform.

4. The method according to claim 1, wherein the method is characterized by: In step S2, the thickness of the prepared metal-based composite coating is 10μm-30μm, and the volume fraction of the second-phase reinforcing particles in the coating is 5%-50%.

5. The method according to claim 1, wherein the method is characterized by: In step S3, the precision processing method is any one of wire cutting, laser cutting, precision stamping, and photochemical etching, and the width of the heat-affected zone of the substrate coating is ≤0.5mm during the processing.

6. The method according to claim 1, wherein the method is characterized by: In step S4, the post-processing of the finished product includes at least one of the following steps: ultrasonic cleaning, deburring, and vacuum drying.

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