Method for preparing wear-resistant coating on surface of ball core of ball valve based on hot-dip plating and rotary extrusion

Abstract

The present application relates to the field of coating preparation, in particular to a kind of ball valve ball core surface wear-resistant coating preparation method based on hot dipping and rotary extrusion. It includes: cleaning ball core matrix, and preheating;Self-fluxing alloy material is heated to molten state, and plating solution is obtained;Adopting fixture clamps ball core matrix, so that the lower half of ball core matrix is immersed in plating solution;Wherein, at the position after ball core matrix is separated from the surface of plating solution, profiling extrusion roller that is consistent with the curvature of outer spherical surface of ball core matrix is arranged, and profiling extrusion roller and ball core matrix maintain rigid gap;Ball core matrix rotates uniformly around its own axis, sweeps through the surface of plating solution, and the attached plating solution forms semi-solid coating before reaching rigid gap using the supercooling degree of ball core matrix;Semi-solid coating is extruded radially by profiling extrusion roller during rigid gap process, and wear-resistant coating is obtained after air cooling.The present application can overcome gravity flow, save secondary sintering process, and realize coating densification and accurate profiling modification at the same time of dipping.

Description

Technical Field

[0001] This invention relates to the field of coating preparation, and specifically to a method for preparing a wear-resistant coating on the surface of a ball valve core based on hot-dip galvanizing and rotary extrusion. Background Technology

[0002] Ball valves are core components in industrial pipeline systems for controlling media flow and switching on / off. The ball core, as a critical opening and closing component, directly determines the valve's sealing performance and service life based on its surface quality. During long-term service, the ball core surface must withstand media erosion, abrasive wear, corrosion, and high-frequency opening and closing impacts. Therefore, surface strengthening treatment to improve wear resistance, corrosion resistance, and interfacial bonding strength is crucial for extending the overall service life of the valve.

[0003] Currently, mainstream technologies for surface strengthening of spherical core curved surfaces include thermal spraying, laser cladding, and static dip coating. However, these methods generally suffer from the following technical bottlenecks when applied to spherical continuous curved surface workpieces: (1) Poor coating uniformity, which easily damages geometric accuracy. The surface of the sphere core is a typical three-dimensional continuous curved surface. In traditional thermal spraying or static dip coating processes, the coating material is significantly affected by the gravitational flow effect in the liquid or semi-solid state. The coating tends to accumulate and thicken in the polar regions of the sphere, while it tends to thin in the equatorial region, forming an obvious uneven thickness distribution, accompanied by "teardrop" drooping defects. This uneven coating not only destroys the original spherical geometric accuracy of the sphere core, but also makes it impossible to restore the ideal sphericity through subsequent precision grinding, directly affecting the sealing and matching performance of the valve; (2) The coating has high porosity, requiring high-energy secondary sintering, which easily leads to thermal deformation. The coatings obtained by conventional dip-plating or spraying are mostly particle accumulation or porous structures with a large number of pores and microcracks inside, resulting in low densification. To achieve coating densification, secondary processing processes such as vacuum high-temperature sintering are usually required, which are energy-intensive and have a long cycle. At the same time, the ball core is prone to thermal deformation and degradation of microstructure and properties during high-temperature sintering. Especially for precision ball cores, the sphericity loss after sintering is difficult to compensate, which seriously reduces the yield and reliability. (3) Coating thickness and solid-liquid state are difficult to coordinate precisely, making subsequent processing difficult. In existing processes, there is a lack of closed-loop control for the thickness accumulation of the coating during deposition and its hardness state (i.e., the ratio of solid to liquid phase) when it reaches the shaping station. If the coating is too thick or over-cured, the subsequent machining allowance is large, the tool wear is severe, and the coating is prone to peeling. If the coating is too soft or too thin, an effective reinforcing layer cannot be formed, and it may even lead to insufficient bonding strength between the coating and the substrate. This mismatch between thickness and state makes it difficult for the ball core to achieve "near-net-shape" reinforcement, which seriously restricts the high-precision and long-life manufacturing of ball valves.

[0004] In summary, existing spherical core surface strengthening technologies struggle to simultaneously achieve uniform coating thickness, low porosity, no secondary sintering thermal deformation, and controllable shaping on spherical continuous curved surfaces. There is an urgent need to develop a spherical core coating preparation process to address these technical challenges. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a method for preparing a wear-resistant coating on the surface of a ball valve core based on hot-dip galvanizing and rotary extrusion. This method can overcome gravity flow, eliminate the secondary sintering process, and achieve coating densification and precise shape correction during galvanizing.

[0006] To solve the above-mentioned technical problems, the technical solution of the present invention is: a method for preparing a wear-resistant coating on the surface of a ball valve core based on hot-dip galvanizing and rotary extrusion, comprising: Clean the spherical core substrate and preheat it; heat the self-fluxing alloy material to a molten state to obtain the plating solution; The ball core substrate is held by a clamp, and the lower half of the ball core substrate is immersed in the plating solution. At the position where the ball core substrate is removed from the plating solution surface, a contour extrusion roller that matches the curvature of the outer spherical surface of the ball core substrate is arranged, and the contour extrusion roller maintains a rigid gap with the ball core substrate. The spherical core substrate rotates uniformly around its own axis, sweeps across the surface of the plating solution, and the plating solution forms a semi-solid coating before reaching the rigid gap by utilizing the supercooling of the spherical core substrate. The semi-solid coating undergoes radial extrusion by a conformal extrusion roller during the rigid gap process, resulting in plastic rheology to compact the dendrite gaps, break up the hard phase, and correct the sphericity. After air cooling, a wear-resistant coating is obtained.

[0007] Furthermore, the formula for calculating the rotational speed N of the spherical core matrix about its own axis is: ; In the formula: Set the rotational speed (r / min) for the spherical core substrate; For dynamic coating arc factor, The vertical depth (mm) of the sphere core substrate partially immersed in the plating solution. The outer diameter of the spherical core substrate (mm); Target coating thickness (mm); Temperature of the plating solution (°C); Preheating temperature of the substrate (°C); The solidus temperature (°C) of the self-fluxing alloy material; This is a corrected kinetic constant that combines the dimensions of the spherical core matrix with the thermal conductivity of the material.

[0008] Furthermore, the size of the rigid gap is equal to the target coating thickness.

[0009] Furthermore, the core matrix is ​​made of 304L stainless steel, and the self-fluxing alloy material is a Ni-Cr-B-Si alloy.

[0010] Furthermore, the preheating temperature of the spherical core substrate is 200~600℃, and the plating bath temperature is 1200~1400℃.

[0011] The present invention also relates to an apparatus for implementing the method for preparing a wear-resistant coating on the surface of a ball valve core based on hot-dip galvanizing and rotary extrusion, comprising: A molten pool is a plating solution used to contain molten self-fluxing alloy materials. A clamp is used to hold the ball core substrate and drive its rotation, with the lower half of the held ball core substrate immersed in the plating solution; The contour extrusion roller has a circumferential curvature that matches the outer spherical curvature of the spherical core substrate. It is positioned after the spherical core substrate is removed from the plating solution and maintains a rigid gap with the spherical core substrate.

[0012] By adopting the above technical solution, the horizontal partial dip-coating method of this invention achieves dynamic full-coverage slurry coating. The rotating dynamic slurry coating overcomes the influence of gravity, eliminating the thickness difference between the poles and the equator of the sphere caused by traditional dip-coating at its physical source. Simultaneously, the substrate supercooling achieves a semi-solid phase change, and the semi-solid in-situ contour extrusion replaces the traditional "cold coating + secondary vacuum sintering," not only eliminating porosity and refining grains but also directly imparting extremely high coating thickness and spherical accuracy. This meets the engineering requirements of high-end ball valves for high precision, high reliability, and long lifespan of the ball core. Attached Figure Description

[0013] Figure 1 This is a flowchart of the method for preparing a wear-resistant coating on the surface of a ball valve core based on hot-dip galvanizing and rotary extrusion according to the present invention. Figure 2 A simplified diagram of the device of the present invention from one perspective; Figure 3 A simplified diagram of the device of the present invention from another perspective; Figure 4 The images show the surface morphology of the samples prepared in Examples 1 to 3. Figure 5 The microhardness gradient distribution curves of the cross sections of the samples prepared in Examples 1 to 3 are shown. Figure 6 A cross-sectional scanning electron microscope image of the sample prepared in Comparative Example 1; Figure 7 The EDS spectrum of the sample prepared in Example 1; Figure 8 The image shows the EDS spectrum of the sample prepared in Example 2. Figure 9 The image shows the EDS spectrum of the sample prepared in Example 3; In the diagram, 1. Sphere core substrate; 2. Contouring extrusion roller; 3. Molten pool; 4. Fixture; Figure 4 In the figure, (a), (b), and (c) are surface morphology images of the samples prepared in Example 1, Example 2, and Example 3, respectively; Figure 5 In the figure, (a), (b) and (c) are the cross-sectional microhardness gradient distribution curves of the samples prepared in Example 1, Example 2 and Example 3, respectively. Detailed Implementation

[0014] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0015] like Figure 1 As shown, a method for preparing a wear-resistant coating on the surface of a ball valve core based on hot-dip galvanizing and rotary extrusion includes the following steps.

[0016] A. Clean the core substrate 1 and preheat it; heat the self-fluxing alloy material to a molten state to obtain the plating solution.

[0017] Specifically, the process involves selecting a ball valve core substrate 1, sandblasting its surface, and then ultrasonically cleaning it with anhydrous ethanol or acetone to remove surface oil and impurities. After cleaning, the core substrate 1 is placed in a heating furnace and preheated to the set preheating temperature. To regulate the quenching effect of the spherical core matrix 1 on the subsequent liquid alloy, a self-fluxing alloy material was selected and heated to a completely molten state in an induction melting furnace, establishing and maintaining a temperature of [temperature value missing]. A constant-temperature, high-temperature liquid molten pool.

[0018] B. The spherical core substrate 1 is held in place by a clamp 4, immersing the lower half of the spherical core substrate 1 in the plating solution. A contouring extrusion roller 2, matching the curvature of the outer spherical surface of the spherical core substrate 1, is positioned after the spherical core substrate 1 has detached from the plating solution surface. The contouring extrusion roller 2 maintains a rigid gap with the spherical core substrate 1. The size of this rigid gap can be equal to the target coating thickness. To ensure the uniformity of the coating thickness, the rigid gap between the contouring extrusion roller 2 and the spherical core substrate 1 is equal at all points.

[0019] C. The spherical core substrate 1 rotates at a constant speed around its own axis, sweeps across the surface of the plating solution, and the plating solution forms a semi-solid coating before reaching the rigid gap by utilizing the supercooling of the spherical core substrate 1. When the spherical core substrate 1 rotates and sweeps across the liquid surface, a layer of liquid alloy is dynamically attached to the surface. The centrifugal force and surface tension generated by continuous rotation effectively balance the gravitational flow. As the attached layer detaches from the liquid surface, the liquid alloy rapidly cools down and crosses the liquidus line, entering the semi-solid region with excellent plastic rheological capabilities, relying on the supercooling of the substrate.

[0020] D. The semi-solid coating is radially extruded by the conformal extrusion roller 2 during the rigid gap process, which causes plastic rheology to compact the dendrite gaps, break up the hard phase and correct the sphericity. After air cooling, a wear-resistant coating is obtained.

[0021] In this process, the spherical core substrate 1 carrying the semi-solid coating rotates continuously through a rigid gap, while the contouring extrusion roller 2 applies continuous radial contouring pressure to the coating, forcing the semi-solid material to undergo plastic rheology, compacting the micro-dendritic gaps and breaking up the coarse hard phases, while precisely correcting the sphericity. After air-cooling and curing, a wear-resistant coating with uniform thickness, density, and metallurgical bonding is obtained.

[0022] Preferably, the formula for calculating the rotational speed N of the spherical core substrate 1 about its own axis can be: ; In the formula: Set the rotational speed (r / min) for the spherical core substrate 1; For dynamic coating arc factor, The vertical depth (mm) of the sphere core substrate 1 partially immersed in the plating solution. The outer diameter of the spherical core substrate 1 (mm); Target coating thickness (mm); Temperature of the plating solution (°C); Preheating temperature of the substrate (°C); The solidus temperature (°C) of the self-fluxing alloy material; The corrected kinetic constant is a combination of the size of the spherical core matrix 1 and the thermal conductivity of the material.

[0023] The core purpose of using this adaptive matching formula (the calculation formula above) is to solve the technical pain point of uncontrollable hot and cold states when the coating reaches the extrusion station. This formula determines the kinematic parameters (rotation speed N) and geometric parameters (immersion depth H, core outer diameter D, target coating thickness) of the ball core substrate 1. ) and thermodynamic parameters , , Quantitative binding was implemented. This ensured that, under different immersion depths and temperature gradients, after the coating detached from the liquid surface, it reached the semi-solid region with optimal plastic rheological capacity upon reaching the rigid gap via a matched optimal rotational speed. Specifically, the matching formula between rotational speed and thermodynamic parameters adaptively adjusted the cooling time under different temperature differences by changing the rotational speed, ensuring that the coating reaching the extrusion zone always maintained an ideal thickness and optimal plasticity.

[0024] It should be noted that the corrected kinetic constants This is a semi-empirical constant that integrates the equipment environment and material properties. In practical applications, This covers the convective heat transfer coefficient, thermal conductivity of the spherical core matrix 1, and latent heat and specific heat capacity of the self-fluxing alloy under specific equipment conditions. By conducting a benchmark no-load measurement experiment under a fixed gap (with the same dimensions as the rigid gap) and standard temperature difference, the applicable parameters for this type of equipment and material combination can be deduced. value.

[0025] In a specific example, a 304L stainless steel sphere core with an inner diameter of 50mm and an outer diameter of 83.4mm was used as the substrate, and the coating material was selected as a Ni-Cr-B-Si self-fluxing alloy (solid phase line). = 1050℃); Target coating thickness (roller gap) set. = 1.5mm; Equipment matching constant calculated based on this specification. = 14. Preheating temperature of spherical core substrate 1 The temperature ranges from 200 to 600℃, and the temperature of the plating solution is [missing information]. The temperature range is 1200~1400℃.

[0026] The specific example will be described in detail below with reference to specific embodiments and comparative examples.

[0027] Example 1: Low temperature plating solution and low temperature preheating condition (strong quenching and high speed rotation).

[0028] The method for preparing a wear-resistant coating on the surface of a ball valve core based on hot-dip galvanizing and rotary extrusion includes the following steps.

[0029] Step S1, Pretreatment: After sandblasting and cleaning the 304L stainless steel ball core substrate 1, place it in a preheating furnace and heat it to the preheating temperature. = 200℃.

[0030] Melting: The Ni-Cr-B-Si alloy is melted in an induction melting furnace while maintaining the plating bath temperature. = 1200℃.

[0031] Step S2, Rotational speed calculation: ; in, =14, H=7mm, D=83.4mm, =1.5mm, =1050℃.

[0032] Substitute into the formula , .

[0033] Step S3, Rotary Dipping and Semi-Solid Slurry Coating: The spherical core substrate 1 rotates locally in the molten pool 3 at a calculated rotation speed, and the liquid alloy enters the semi-solid paste region by relying on the supercooling of the spherical core substrate 1.

[0034] Under shallow immersion (7mm) and strong cooling conditions, the system automatically matched an operating speed of 11.6 r / min to prevent the coating from over-solidifying after exiting the liquid surface. This speed precisely balances the "time required for short arc long coating" and the "coating cooling rate in air", so that the coating is exactly in a soft semi-solid state of 1.5mm when it reaches the contour extrusion roller 2.

[0035] It is important to note that the intense cooling condition here specifically refers to a temperature gradient of up to 1000°C between the high-temperature liquid alloy at 1200°C and the low-temperature preheated substrate at 200°C. This large temperature difference causes the heat to be rapidly drawn away from the liquid alloy upon contact with the substrate, resulting in an extremely fast surface cooling rate and a rapid solidification process.

[0036] Step S4, semi-solid phase change and contour extrusion: Under a fixed gap, the semi-solid coating is rolled in situ using contour extrusion roller 2 to eliminate micropores and correct sphericity.

[0037] Step S5, cooling and solidification: the ball core is air-cooled to room temperature as it rotates, resulting in a dense, precisely shaped metallurgical bonding coating.

[0038] Performance characterization of the samples in this embodiment: Microstructure: such as Figure 4 As shown in (a), the surface cooling rate is extremely fast at high rotation speeds, and the coating exhibits a fine equiaxed crystal structure. Figure 7 As shown in the EDS energy dispersive spectroscopy analysis and Table 1, the coating detection area is mainly composed of Ni (48.08 wt%) and Fe (29.20 wt%). Due to the excessively rapid cooling rate, the deep diffusion of elements and the large-scale aggregation of complex hard phases are limited. The C content is 2.39 wt%, and no obvious coarse boride precipitation is observed. Table 1:

[0039] Cross-sectional hardness: such as Figure 5 As shown in (a), the cross-sectional hardness exhibits a typical metallurgical bonding step distribution (eight coating test points are equidistantly distributed in a straight line from the outer coating layer to the inner substrate along the normal direction perpendicular to the coating surface. The first six test points are located inside the Ni-Cr-B-Si coating, while the seventh and eighth points cross the metallurgical bonding interface and are located inside the 304L stainless steel substrate). The hardness of the first six coating test points fluctuates between 766.7 and 894.9 HV 0.5, and then rapidly and steadily decreases to the 304L substrate hardness of 178.7 HV 0.5 at the seventh and eighth points, indicating that there is no brittle fracture cliff at the interface; Surface roughness: Rapid light-load surface smoothing was used, and the surface roughness performance was good, with an Ra test value of 2.54μm.

[0040] Example 2: Medium-temperature plating solution and high-temperature preheating conditions (moderate thermodynamic gradient and medium-speed rotation).

[0041] The difference between this embodiment and Embodiment 1 is that: In step S1, the preheating temperature of the spherical core substrate 1 is... = 600℃, maintain the plating bath temperature = 1300℃; In step S2, the calculated rotational speed ; In step S3, the control system automatically reduces the lifting speed to a low-to-medium speed of 4.9 r / min. This slow and smooth rotation allows the semi-solid alloy sufficient time to complete metallurgical adhesion on the short arc surface and maintains the optimal paste-like zone upon reaching the extrusion wheel, compacting the micro-shrinkage cavities.

[0042] Performance characterization of the samples in this embodiment: Microstructure: such as Figure 4 As shown in (b), the internal structure is extremely dense, and the interdendritic shrinkage cavities are completely eliminated. Figure 8 The EDS energy dispersive spectroscopy analysis shown and Table 2 indicate that the compositional distribution has reached the optimal equilibrium, with B (3.64 wt%), C (2.95 wt%), and Cr (18.28 wt%) detected. This indicates that the brittle hard phase was effectively broken up by the medium-load mechanical force and is uniformly distributed in the matrix in a diffuse manner. Table 2:

[0043] Cross-sectional hardness: such as Figure 5 As shown in (b), the hardness exhibits a smooth gradient distribution (eight coating test points are equidistantly distributed in a straight line from the outer coating layer to the inner substrate along the normal direction perpendicular to the coating surface. The first six test points are located inside the Ni-Cr-B-Si coating, while the seventh and eighth points cross the metallurgical interface and are located inside the 304L stainless steel substrate). The hardness of the first six coating test points remains at a high level of 728.6 ~ 814.2 HV 0.5, and then drops to around 187.1 HV 0.5 in the substrate region. The overall average hardness is better than that of Example 1. Surface roughness: Under optimal semi-solid deformation and fixed gap conformal extrusion, the surface plastic flow is extremely smooth, and the roughness Ra is as low as 1.49 μm.

[0044] Example 3: High-temperature plating solution and high-temperature preheating conditions (high enthalpy, low-speed rotation).

[0045] The difference between this embodiment and Embodiment 1 is that: In step S1, the preheating temperature of the spherical core substrate 1 is... = 600℃, maintain the plating bath temperature = 1400℃; In step S2, the calculated rotational speed ; In step S3, the equipment is precisely matched to a low-speed operation of 4.0 r / min. The slow lifting process not only ensures sufficient coating under the minimal immersion surface, but also ensures that the coating carrying a large amount of heat energy just crosses the critical cooling point when it reaches the contouring extrusion roller 2, so as to withstand the contouring and densification shaping by the contouring extrusion roller 2.

[0046] Performance characterization of the samples in this embodiment: Microstructure: such as Figure 4 Image (c) shows that the coating underwent deep solid-phase plastic deformation. The prolonged cooling cycle allowed the hard phase to fully dissociate and precipitate, from... Figure 9 The EDS energy dispersive spectroscopy analysis shown and Table 3 show that B in this region is as high as 8.84 wt% and Cr is 20.36 wt%, indicating that a large number of high-hardness compounds such as Cr-B and Cr-C underwent severe fragmentation, refinement and segregation under this heavy load. Table 3:

[0047] Cross-sectional hardness: such as Figure 5 As shown in (c), due to the work hardening caused by grain fragmentation and refinement and the dispersion of a large number of hard phases, the hardness of the first 6 coating test points increases stepwise, with a fluctuation range of 839.7 ~ 920.6 HV 0.5, and the highest peak value exceeds 920 HV; the matrix hardness of the last 2 points is about 198.2 HV 0.5, and the bonding zone is extremely deep. Surface roughness: Due to the influence of strong heavy-load rolling and high solid phase deformation resistance, the surface inevitably has micro-plastic fluctuations, and the surface roughness Ra increases to 2.91 μm.

[0048] The surface roughness test results of the samples prepared in Examples 1 to 3 are shown in Table 4.

[0049] Table 4:

[0050]

[0051] A comprehensive comparison of Examples 1 to 3 reveals that the matching of thermodynamic parameters and rotational speed directly determines the microscopic evolution and macroscopic properties of the coating: Example 1 (intense cooling) primarily focuses on fine-grain strengthening. Due to the extremely rapid cooling rate limiting element diffusion, fewer brittle hard phases precipitate, resulting in relatively low overall hardness. Example 2 (moderate temperature difference) achieves the optimal balance between microscopic density and macroscopic smoothness, obtaining the lowest surface roughness and excellent hardness gradient. Example 3 (high enthalpy, low speed) utilizes a long cooling cycle to induce deep thermodynamic reactions within the coating. A large amount of high-hardness, brittle compounds such as CrC and CrB are fully precipitated and refined and segregated under heavy loads, leading to a step-like increase in surface hardness and exhibiting extreme wear resistance. Overall, this process demonstrates that customized control can be achieved between "high precision" and "high hardness."

[0052] Comparative Example 1: Low plating solution temperature mismatch condition.

[0053] The difference between this comparative example and Example 1 is as follows: In step S1, the preheating temperature of the spherical core substrate 1 is... = 400℃ (within the set preheating range), maintain the plating bath temperature = 1100℃ (approaching the solidus line of the alloy at 1050℃); In step S2, the calculated rotational speed ; In step S3, the equipment is precisely matched. The rotational speed.

[0054] Performance characterization and test results of this comparative example: In stark contrast to Examples 1 to 3, the coating prepared in this comparative example exhibits extremely poor surface roughness and severe coating peeling. Scanning electron microscopy (SEM) observation of its cross-section revealed the following results: Figure 6 As shown. From Figure 6 It can be clearly observed that the coating and the core substrate 1 failed to form a good metallurgical bond, and there are a lot of defects at the interface.

[0055] The cause of this defect is that although the preheating temperature of the core substrate 1 at 400℃ is within a reasonable range, the plating bath temperature is too low, with a temperature difference of only 50℃ from the solidus of the alloy. This results in a severe deficiency of the enthalpy of the liquid alloy, leading to poor fluidity and interfacial wettability. Upon contact with the core substrate 1, only localized, shallow element diffusion occurs at the interface, failing to form a dense, continuous, high-strength metallurgical bond. Simultaneously, due to the low superheat, the coating rapidly crosses the solidus and loses its plasticity within a very short time. Subsequently, when the core carrying this hard coating passes through a dumbbell-shaped contoured roller with a rigid fixed gap, the enormous radial rolling pressure and frictional shear force directly act on the already fragile and micro-defect-ridden interface, causing the originally few local bonding points to be forcibly torn apart, ultimately resulting in large-area interfacial peeling along the defects on a macroscopic scale.

[0056] like Figure 2 and Figure 3 As shown, an apparatus for implementing the above-described method for preparing a wear-resistant coating on the surface of a ball valve core based on hot-dip galvanizing and rotary extrusion includes: Molten pool 3 is used to contain the plating solution formed by the melting of self-fluxing alloy materials; The clamp 4 is used to hold the ball core substrate 1 and drive it to rotate, so that the lower half of the held ball core substrate 1 is immersed in the plating solution. The contour extrusion roller 2 has a circumferential curvature that matches the outer spherical curvature of the spherical core substrate 1. It is positioned after the spherical core substrate 1 is removed from the plating solution surface and maintains a rigid gap with the spherical core substrate 1.

[0057] It should be noted that, Figure 2 and Figure 3 This is a simplified diagram to illustrate the relative positional relationship between the contouring extrusion roller 2 and the ball core substrate 1. The fixture involved in this embodiment is a mature existing technology, and can be, but is not limited to, the support fixture and motor described in the applicant's previous application with application number CN202520457909.3.

[0058] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A method for preparing a wear-resistant coating on the surface of a ball valve core based on hot-dip galvanizing and rotary extrusion, characterized in that, include: Clean the spherical core substrate (1) and preheat it; heat the self-fluxing alloy material to a molten state to obtain the plating solution; The ball core substrate (1) is held by a clamp (4) so ​​that the lower half of the ball core substrate (1) is immersed in the plating solution; wherein, at the position after the ball core substrate (1) is removed from the plating solution surface, a contour extrusion roller (2) that matches the curvature of the outer spherical surface of the ball core substrate (1) is arranged, and the contour extrusion roller (2) maintains a rigid gap with the ball core substrate (1); The spherical core substrate (1) rotates uniformly around its own axis, sweeps across the plating solution surface, and the plating solution attached to it forms a semi-solid coating before reaching the rigid gap by utilizing the supercooling of the spherical core substrate (1). The semi-solid coating is radially extruded by the conformal extrusion roller (2) during the rigid gap process, and plastic rheology occurs to compact the dendrite gap, break the hard phase and correct the sphericity. After air cooling, a wear-resistant coating is obtained. The formula for calculating the speed N of the spherical core matrix (1) rotating about its own axis is: ； In the formula: Set the rotational speed (r / min) for the spherical core substrate (1); For dynamic coating arc factor, The vertical depth (mm) of the sphere core substrate (1) partially immersed in the plating solution. The outer diameter (mm) of the spherical core matrix (1); Target coating thickness (mm); Temperature of the plating solution (°C); Preheating temperature of the substrate (°C); The solidus temperature (°C) of the self-fluxing alloy material; The corrected kinetic constant is a combination of the size of the spherical core matrix (1) and the thermal conductivity of the material.

2. The method for preparing a wear-resistant coating on the surface of a ball valve core based on hot-dip galvanizing and rotary extrusion according to claim 1, characterized in that, The size of the rigid gap is equal to the target coating thickness.

3. The method for preparing a wear-resistant coating on the surface of a ball valve core based on hot-dip galvanizing and rotary extrusion according to claim 1, characterized in that, The core matrix (1) is made of 304L and the self-fluxing alloy material is Ni-Cr-B-Si alloy.

4. The method for preparing a wear-resistant coating on the surface of a ball valve core based on hot-dip galvanizing and rotary extrusion according to claim 3, characterized in that, The preheating temperature of the spherical core substrate (1) is 200~600℃, and the plating solution temperature is 1200~1400℃.

5. An apparatus for implementing the method for preparing a wear-resistant coating on the surface of a ball valve core based on hot-dip galvanizing and rotary extrusion as described in any one of claims 1-4, characterized in that, include: The molten pool (3) is used to hold the plating solution formed by melting self-fluxing alloy materials; The clamp (4) is used to hold the ball core substrate (1) and drive it to rotate, and the lower half of the held ball core substrate (1) is immersed in the plating solution; The contour extrusion roller (2) has a circumferential curvature that matches the outer spherical curvature of the spherical core substrate (1), and is arranged at the position after the spherical core substrate (1) is separated from the plating liquid surface, and maintains a rigid gap with the spherical core substrate (1).

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