Electroplated coating on surface of inner wall of ball milling tank and preparation method of electroplated coating

Abstract

The invention relates to an electroplated coating on the surface of the inner wall of a ball-milling tank and a preparation method of the electroplated coating. The electroplated coating comprises a pre-electroplated layer located on the inner wall of a tank body of the ball-milling tank and an overall electroplated layer located on the surface of the pre-electroplated layer. Wherein a gradient transition layer with continuously changed components is formed between the pre-electroplated layer and the overall electroplated layer, and the atomic percentage content of each metal element in the gradient transition layer is continuously and linearly changed in the direction from the pre-electroplated layer to the overall electroplated layer; according to the electroplated coating on the surface of the inner wall of the ball milling tank and the preparation method of the electroplated coating, the gradient transition layer with continuously changed components is formed between the pre-electroplated layer and the overall electroplated layer, and the high hardness of the pre-electroplated layer and the low surface energy characteristic of the overall electroplated layer are combined; the technical contradiction that a traditional coating is insufficient in interface bonding strength and poor in surface adhesion resistance is effectively solved, and the coating has the advantages that the powder adhesion rate is remarkably reduced, the impact resistance of the coating is improved, and the service life of equipment is prolonged.

Description

Technical Field

[0001] The present application relates to the technical field of electroplating layer preparation, and in particular to an electroplating coating on the inner wall surface of a ball mill jar and a preparation method thereof. Background Art

[0002] Ball mill is an important equipment in the field of powder processing. The inner wall surface treatment technology directly affects the grinding effect. In practical applications, the powder adhesion problem has always been the main bottleneck restricting production efficiency, especially when processing highly viscous materials.

[0003] Currently, the industry primarily utilizes two technical solutions: high-finish metal inner walls and ceramic coatings. While metal inner walls offer excellent mechanical properties, they are prone to adhesion when handling fine powders. While ceramic coatings offer superior surface properties, they are prone to microcracks under high-intensity impact, exacerbating the problem of powder embedding.

[0004] Both of the aforementioned technologies have significant limitations: metal materials are difficult to avoid powder adhesion, while ceramic materials have brittle defects. This contradiction results in the existing technology being ineffective when processing highly viscous materials, which not only affects production efficiency but also increases equipment maintenance costs. At the same time, frequent downtime for cleaning also seriously affects production continuity. In addition, traditional coating technology also has technical defects such as insufficient interface bonding strength and discontinuous composition gradient changes. These problems urgently need to be solved. To address these issues, the existing technology urgently needs to be improved. Summary of the Invention

[0005] In order to solve the above-mentioned defects, the present application provides an electroplating coating on the inner wall surface of a ball mill and a preparation method thereof.

[0006] The above-mentioned invention objective of this application is achieved through the following technical solutions:

[0007] An electroplating coating on the inner wall surface of a ball mill jar, comprising:

[0008] A pre-plating layer located on the inner wall of the ball mill tank and an integral plating layer located on the surface of the pre-plating layer;

[0009] The atomic percentages of the metal elements in the pre-electroplating layer are: Al: 15-25%, Ti: 15-25%, V: 10-20%, Zr: 10-20%, Cr: 15-25%, Mo: 10-20%;

[0010] The atomic percentages of the metal elements in the overall electroplating layer are: Al: 20-30%, Ti: 20-30%, V: 10-15%, Zr: 10-15%, Cr: 15-20%, Mo: 10-15%;

[0011] A gradient transition layer with continuously changing composition is formed between the pre-plating layer and the overall plating layer, and the atomic percentage content of each metal element in the gradient transition layer changes continuously and linearly from the pre-plating layer to the overall plating layer.

[0012] Furthermore, the present application also proposes that the thickness of the pre-electroplating layer is 100-200 μm, and its microhardness is greater than or equal to HV800.

[0013] Furthermore, the present application also proposes that the thickness of the overall electroplating layer is 300-500 μm, and its surface energy is less than or equal to 30 mJ / m 2 .

[0014] Furthermore, the present application also proposes that the thickness of the gradient transition layer is 50-100 μm, and the hardness thereof increases continuously from HV800 to HV1000 in the direction from the pre-electroplating layer to the overall electroplating layer.

[0015] Furthermore, the present application also proposes that the overall electroplating layer is prepared by an electroplating process, and its surface roughness Ra is less than or equal to 0.1 μm.

[0016] Furthermore, the present application also proposes that an in-situ Al2O3 / TiO2 composite oxide film is formed in the gradient transition layer, and the film thickness is 5-15 nm.

[0017] The second object of the present invention is achieved through the following technical solutions:

[0018] A method for preparing an electroplated coating on the inner wall surface of a ball mill jar comprises the following steps:

[0019] S1. Matrix pretreatment: The inner wall of the ball mill is subjected to mechanical polishing, electrochemical degreasing, electrolytic polishing and pickling activation treatment in sequence;

[0020] S2. Preparation of pre-plating layer: using supersonic arc spraying equipment to deposit an Al-Ti-V-Zr-Cr-Mo multi-principal alloy layer on the pretreated substrate surface to form a pre-plating layer;

[0021] S3. Preparation of the overall electroplating layer: preparing an electroplating solution according to a ratio, and depositing it on the surface of the pre-electroplating layer to form an overall electroplating layer;

[0022] S4, post-processing: heat-treating the plated workpiece obtained after step S3 at 250-300° C. under nitrogen protection for 2-3 hours, mechanically polishing with diamond paste, and sequentially performing chromate passivation treatment and silane coupling agent sealing treatment.

[0023] Furthermore, the present application also proposes that in the step S1, the mechanical polishing adopts a planetary grinder, and 400#, 800#, and 1200# diamond abrasives are used in sequence to grade and polish the inner wall surface of the ball mill jar to a roughness Ra of less than or equal to 0.8 μm;

[0024] The electrochemical degreasing adopts an alkaline solution containing 50g / L NaOH and 30g / L Na3PO4 at 60-80℃ and 2-3A / dm 2 Current density electrolysis treatment for 15-20min;

[0025] The electrolytic polishing is performed using a mixed electrolyte of phosphoric acid and sulfuric acid in a volume ratio of 3:1 at a voltage of 12-15V until the surface roughness Ra of the inner wall of the ball mill is less than or equal to 0.2 μm;

[0026] The acid washing and activation is carried out by soaking in a 10% HCl+5% HF mixed acid solution at room temperature for 30-60 seconds.

[0027] Furthermore, the present application also proposes that in step S2, the deposition working voltage is 32-36V, the deposition working current is 150-200A, the deposition spraying distance is 150-200mm, the deposition powder feeding rate is 30-50g / min, the purity of the Ar protective gas is greater than or equal to 99.99%, the thickness of the pre-electroplating layer is 100-200μm, the grain size is 20-50nm, and the porosity is less than or equal to 0.2%.

[0028] Furthermore, the present application also proposes that in step S3, the electroplating solution includes 50-70 g / L of Al(NO3)3·9H2O, 30-50 g / L of Ti(SO4)2, 20-30 g / L of VOSO4, 15-25 g / L of ZrCl4, 40-60 g / L of CrCl3, and 30-50 g / L of MoO3; the deposition current density is 2-5 A / dm 2 The deposition temperature is 30-40°C, the deposition pH value is 3-5, the deposition time is 90-150min, the thickness of the overall electroplating layer is 300-500μm, and the surface energy is less than or equal to 30mJ / m 2 ;

[0029] The electroplating solution further includes 50-80 g / L of Na2SO4 as a conductive salt and 10-15 g / L of sodium citrate as a buffer.

[0030] From the above, it can be seen that the electroplating coating on the inner wall surface of the ball mill jar and its preparation method provided in this application, by forming a gradient transition layer with continuously changing composition between the pre-electroplating layer and the overall electroplating layer, combined with the high hardness of the pre-electroplating layer and the low surface energy characteristics of the overall electroplating layer, effectively solves the technical contradiction of insufficient interface bonding strength and poor surface anti-adhesion performance of traditional coatings, and has the advantages of significantly reducing powder adhesion rate, improving coating impact resistance and extending equipment service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a schematic structural diagram of an embodiment of an electroplated coating on the inner wall surface of a ball mill jar according to the present application;

[0032] Figure 2 This is a flow chart of an embodiment of a method for preparing an electroplating coating on the inner wall surface of a ball mill jar in the present application. DETAILED DESCRIPTION

[0033] The technical solutions of this application will be described clearly and completely below, in conjunction with the accompanying drawings. It should be understood that the described embodiments represent only a portion of the embodiments of this application, and not all of them. The components of this application, generally described and illustrated in the drawings herein, may be arranged and designed in a variety of different configurations. Therefore, the following detailed description of the embodiments of this application provided in the drawings is not intended to limit the scope of the claimed application, but rather merely represents selected embodiments of this application. All other embodiments derived by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application. It should be noted that similar reference numerals and letters represent similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings. Furthermore, in the description of this application, the terms "first," "second," etc., are used solely to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0034] Existing ball mill surface treatment technologies have long faced a dilemma between metal and ceramic materials. While metal inner walls offer excellent mechanical strength, they are prone to material adhesion when grinding fine powders. Ceramic coatings, while offering excellent surface properties, suffer from brittle defects and are prone to microcracks under sustained impact. Neither of these traditional solutions effectively balances impact resistance with anti-adhesion requirements, leading to frequent maintenance downtime when processing highly viscous materials and severely limiting production efficiency.

[0035] To address these issues, the research and development process revealed that the performance conflict between metal and ceramic materials stems from the abrupt nature of interfacial bonding. Analyzing coating failure mechanisms, they realized that a single-component coating could not simultaneously meet both interfacial bonding strength and surface functional requirements. This led to the idea of ​​constructing a gradient composite structure, attempting to achieve a progressive matching of material properties through a continuous transition of components, thereby maintaining substrate support strength while optimizing surface functional properties.

[0036] In one embodiment, if Figure 1 As shown, the present application discloses an electroplating coating on the inner wall surface of a ball mill jar, specifically comprising:

[0037] A pre-plating layer located on the inner wall of the ball mill tank and an integral plating layer located on the surface of the pre-plating layer;

[0038] The atomic percentages of the metal elements in the pre-electroplating layer are: Al: 15-25%, Ti: 15-25%, V: 10-20%, Zr: 10-20%, Cr: 15-25%, Mo: 10-20%;

[0039] The atomic percentages of the metal elements in the overall electroplating layer are: Al: 20-30%, Ti: 20-30%, V: 10-15%, Zr: 10-15%, Cr: 15-20%, Mo: 10-15%;

[0040] A gradient transition layer with continuously changing composition is formed between the pre-plating layer and the overall plating layer, and the atomic percentage content of each metal element in the gradient transition layer changes continuously and linearly from the pre-plating layer to the overall plating layer.

[0041] In this embodiment, the pre-electroplating layer refers to an alloy deposition layer that is in direct contact with the substrate, which can be specifically achieved by a supersonic arc spraying process, and a high-hardness base is formed by regulating the ratio of metal elements; the pre-electroplating layer serves as a supporting structure and can effectively disperse mechanical impact stress; the integral electroplating layer refers to an outer functional deposition layer, which can be specifically formed by an electrochemical deposition process, and the surface energy is reduced after adjusting the element ratio; the integral electroplating layer is in direct contact with the material and is responsible for improving the anti-adhesion performance; the gradient transition layer refers to the transition area connecting the two main layers, which is specifically achieved by controlling the electroplating parameters to make the element content linearly gradient. The gradient transition layer can eliminate the stress concentration caused by interface mutations.

[0042] Specifically, the pre-electroplating layer enhances the substrate's deformation resistance through its high hardness characteristics, and its multi-principal element alloy design improves the grain boundary strengthening effect; the overall electroplating layer reduces the surface free energy by optimizing the element ratio to form a dense and stable surface structure; the gradient transition layer achieves elastic modulus transition through continuous changes in composition, forming a stress buffer zone when subjected to impact loads; when the three-layer structure works synergistically, the base layer resists plastic deformation, the transition layer relieves stress concentration, and the functional layer inhibits material adhesion, jointly achieving long-term and stable operation.

[0043] Compared with existing technologies, traditional metal inner walls have too high surface energy due to their single component, and ceramic coatings are prone to interface peeling due to their brittle and hard properties. This solution breaks through the material performance boundaries through a gradient composite structure, maintaining the toughness advantage of metal materials while giving the surface ceramic materials low viscosity properties; the continuous component design of the transition layer effectively avoids the interface failure risk of traditional laminated structures, achieving a synergistic improvement in overall performance.

[0044] Through the above technical solution, this application solves the problem of wall sticking during the grinding process of highly viscous materials, significantly reduces the frequency of shutdowns for cleaning, and the composite coating structure effectively inhibits crack propagation while maintaining mechanical strength, thereby extending the equipment maintenance cycle; the gradient transition design ensures the structural integrity of the coating system under long-term impact conditions, providing a reliable surface protection solution for ball mill equipment.

[0045] In one embodiment, the thickness of the pre-electroplating layer is 100-200 μm, and the microhardness thereof is greater than or equal to HV800.

[0046] In this embodiment, the thickness of the pre-electroplating layer refers to the vertical dimension of the covering layer formed by the metal deposition layer on the surface of the substrate, which can be achieved by controlling the deposition rate and time using a supersonic arc spraying process. This thickness range can ensure the formation of an effective bonding interface between the coating and the substrate while avoiding stress concentration caused by excessive thickness; microhardness refers to an indicator of the material's ability to resist plastic deformation, which can be achieved by optimizing the density of the alloy layer by regulating the spraying process parameters. This hardness threshold can effectively resist surface indentations caused by the impact of abrasive media.

[0047] Specifically, the pre-electroplating layer forms a metal alloy layer in a specific thickness range by precisely controlling the deposition process, and constructs a transition structure with gradient characteristics on the surface of the substrate. This thickness range can not only provide sufficient mechanical support strength, but also avoid the accumulation of stress inside the coating due to excessive thickness; the microhardness index forms a fine-grained strengthening structure on the coating surface by optimizing the alloy element ratio and deposition conditions, thereby maintaining surface integrity when subjected to periodic mechanical loads.

[0048] Through the above technical solution, the present application can form a base structure with excellent mechanical properties, maintain reliable bonding between the coating and the substrate during long-term grinding operations, and reduce powder contamination caused by coating peeling. The high hardness characteristics of the pre-electroplated layer can significantly reduce the scratch depth of the grinding medium on the coating surface, thereby extending the equipment maintenance cycle and improving the grinding efficiency and stability.

[0049] In one embodiment, the thickness of the overall electroplating layer is 300-500 μm, and its surface energy is less than or equal to 30 mJ / m 2 .

[0050] In this embodiment, the thickness of the overall electroplating layer refers to the total height of the metal deposition layer covering the surface of the pre-electroplating layer, which can be achieved by controlling the electroplating time and current density. This thickness range can balance mechanical strength and processing efficiency, and provide an effective protective layer for the inner wall of the ball mill; wherein, the surface energy refers to the energy state per unit area of ​​the solid surface, which can be achieved by adjusting the composition of the electroplating solution and the deposition parameters. Lower surface energy can reduce the interfacial interaction force between the material and the inner wall, thereby inhibiting powder adhesion.

[0051] Specifically, the overall electroplating layer is formed into a continuous and dense covering layer by depositing an alloy of specific composition. The thickness is selected to meet the impact resistance requirements while avoiding the accumulation of internal stress due to excessive thickness. The control of surface energy is achieved by optimizing the metal salt ratio in the electroplating solution and the passivation treatment process, so that the coating surface exhibits low-energy state characteristics. During the ball milling process, the low surface energy characteristics can significantly reduce the van der Waals force and electrostatic adsorption between the powder particles and the inner wall, thereby reducing the amount of material adhesion.

[0052] Through the above technical solution, this application effectively reduces the amount of material adhesion on the inner wall of the ball mill, extends the continuous operation cycle of the equipment, avoids the secondary pollution problem caused by coating cracking, and significantly improves the grinding efficiency of high-viscosity powder materials.

[0053] In one embodiment, the thickness of the gradient transition layer is 50-100 μm, and the hardness thereof increases continuously from HV800 to HV1000 in a direction from the pre-plating layer to the overall plating layer.

[0054] In this embodiment, the gradient transition layer refers to an intermediate structural layer formed between the pre-electroplating layer and the overall electroplating layer, in which the atomic percentage of the metal element continuously changes. Specifically, the composition gradient distribution can be achieved by controlling the electroplating process parameters, which is used to alleviate the interface stress concentration and enhance the interlayer bonding strength; wherein, the thickness range of 50-100μm refers to the vertical size range of the gradient transition layer, which can be specifically controlled by adjusting the electroplating time and current density. This range can not only ensure the sufficiency of the composition gradient change, but also avoid the instability of the coating structure caused by excessive thickness; wherein, the continuous increase in hardness refers to the linear increase of the microhardness from HV800 on the pre-electroplating layer side to HV1000 on the overall electroplating layer side, which is specifically achieved by the combined regulation of the gradient increase of Al and Ti element content and the gradient decrease of Cr and Mo element content, which is used to match the mechanical property differences of adjacent coatings.

[0055] Specifically, an intermediate layer with a continuous composition transition is formed between the pre-plating layer and the overall electroplating layer. By controlling the atomic percentages of Al and Ti elements to gradually increase from the pre-plating layer to the overall electroplating layer, while the atomic percentages of V, Zr, Cr, and Mo elements decrease accordingly, the hardness of the coating presents a linear increasing trend. In this process, the composition gradient change is achieved by segmentally adjusting the concentration of the plating solution components and the deposition current density. For example, during the electroplating process, the supply of Al and Ti sources is gradually increased, while the supply of Cr and Mo sources is reduced. The hardness gradient thus formed can effectively disperse the interface stress and avoid the problem of coating peeling caused by sudden hardness changes.

[0056] Through the above technical solution, this application can effectively improve the anti-peeling performance of the inner wall coating of the ball mill under high-frequency impact conditions, and reduce the risk of coating failure caused by interlayer stress concentration. The gradient transition layer coordinates the composition distribution and hardness matching, which not only avoids the defect of insufficient adhesion of the metal coating, but also overcomes the problem of brittle fracture of the ceramic coating, thereby significantly improving the service stability of the coating during the powder grinding process.

[0057] In one embodiment, the overall electroplating layer is prepared by an electroplating process, and its surface roughness Ra is less than or equal to 0.1 μm.

[0058] In this embodiment, the electroplating process refers to a surface treatment technology that uses the principle of electrolysis to deposit a metal coating on the surface of a substrate. Specifically, it can be achieved by using an electroplating solution containing multiple metal salts in combination with specific current parameters, and a dense and uniform coating is formed by controlling the ion migration rate and deposition conditions; surface roughness Ra refers to a quantitative indicator of the arithmetic mean deviation of the surface profile, and can be achieved by using mechanical polishing with diamond grinding paste combined with an electrochemical polishing process, and reducing surface micro-undulations through a multi-stage polishing process.

[0059] Specifically, when forming an overall electroplating layer on the inner wall surface of the ball mill, the electroplating solution composition and deposition parameters are optimized to enable the metal elements to achieve directional crystal growth on the surface of the pre-electroplating layer; the electric field applied during the electroplating process causes the metal ions to be evenly distributed on the substrate surface, and the subsequent mechanical polishing process is combined to eliminate microscopic protrusions, and finally form a coating with a continuous and dense structure. This process achieves ultra-low surface roughness while ensuring the bonding strength of the coating by balancing the deposition rate and crystallization quality.

[0060] Through the above technical solution, this application effectively reduces the contact area between the inner wall of the ball mill and the powder material, and reduces the mechanical interlocking phenomenon caused by surface micro-depression; in actual operation, the continuous smooth interface formed on the surface of the coating can significantly reduce the adhesion probability of powder particles, extend the continuous operation time of the equipment, and at the same time avoid the interface failure problem caused by the brittleness of traditional ceramic coatings.

[0061] In one embodiment, an in-situ Al2O3 / TiO2 composite oxide film is formed in the gradient transition layer, and the film thickness is 5-15 nm.

[0062] In this embodiment, the in-situ Al2O3 / TiO2 composite oxide film refers to a composite structure of aluminum oxide and titanium oxide spontaneously formed by an oxidation reaction during the electroplating process, which can be achieved by gradient composition control combined with an oxidation treatment process. By controlling the diffusion rate and oxidation conditions of aluminum and titanium elements in the transition layer, the two oxides are uniformly distributed at the nanometer scale; wherein, the film thickness of 5-15nm refers to the thickness range of the composite oxide layer, which can be achieved by adjusting the oxidation time and temperature parameters. This thickness range can balance the surface density and interface bonding strength.

[0063] Specifically, on the substrate with continuously changing composition of the gradient transition layer, aluminum and titanium elements undergo in-situ oxidation reaction with oxygen during heat treatment to form a uniformly distributed Al2O3 and TiO2 nanoparticle composite structure. The composite oxide film covers the surface of the transition layer and is tightly bonded to the metal matrix through chemical bonding. At the same time, the nanometer-scale thickness avoids the problem of brittle cracking caused by excessive film thickness.

[0064] Through the above technical solution, the present application effectively suppresses the adhesion of powder to the inner wall of the ball mill, while avoiding the problem of microcracks in the coating under high-frequency impact, thereby extending the continuous operation cycle of the equipment and reducing maintenance frequency.

[0065] In one embodiment, a method for preparing an electroplated coating on the inner wall surface of a ball mill is provided, such as Figure 2 As shown, the specific steps include:

[0066] S1. Matrix pretreatment: The inner wall of the ball mill is subjected to mechanical polishing, electrochemical degreasing, electrolytic polishing and pickling activation treatment in sequence;

[0067] S2. Preparation of pre-plating layer: using supersonic arc spraying equipment to deposit an Al-Ti-V-Zr-Cr-Mo multi-principal alloy layer on the pretreated substrate surface to form a pre-plating layer;

[0068] S3. Preparation of the overall electroplating layer: preparing an electroplating solution according to a ratio, and depositing it on the surface of the pre-electroplating layer to form an overall electroplating layer;

[0069] S4, post-processing: heat-treating the plated workpiece obtained after step S3 at 250-300° C. under nitrogen protection for 2-3 hours, mechanically polishing with diamond paste, and sequentially performing chromate passivation treatment and silane coupling agent sealing treatment.

[0070] In this embodiment, mechanical polishing refers to the flattening of the substrate surface by abrasives, and specifically, a planetary grinder can be used with diamond abrasives of different mesh sizes to gradually polish the surface to eliminate surface scratches and reduce roughness; electrochemical degreasing refers to the use of electrolytic reaction to remove surface grease, and specifically, an alkaline solution can be used as the electrolyte to decompose organic pollutants through the action of electric current; electrolytic polishing refers to further refining the surface morphology through electrochemical dissolution, and specifically, a mixture of phosphoric acid and sulfuric acid can be used as the electrolyte to achieve microscopic flatness under a specific voltage; pickling activation refers to removing the oxide layer and exposing the fresh metal surface by an acidic solution, and specifically, Short-term immersion in a mixture of hydrochloric acid and hydrofluoric acid can enhance the bonding strength of subsequent coatings; supersonic arc spraying refers to the use of high-speed airflow to accelerate the deposition of metal particles. Specifically, the density of the coating can be controlled by adjusting the voltage, current and powder feeding rate to form a pre-plating layer with a nanocrystalline structure; electroplating solution preparation refers to the dissolution of metal salts in proportion to form an ionic solution. Specifically, conductive salts and buffers can be added to maintain deposition stability, and composition-controlled coating growth can be achieved by controlling current density and temperature; heat treatment refers to the elimination of internal stress in the coating at a certain temperature. Specifically, inert gas protection can be used to prevent oxidation, and mechanical polishing and passivation sealing treatment can be combined to improve surface performance.

[0071] Specifically, in the substrate pretreatment stage, a clean and activated base is established through multi-level surface treatment, the pre-electroplating layer forms a dense transition layer through high-speed particle deposition, the overall electroplating layer realizes composition gradient regulation through electrochemical deposition, and the post-treatment stage enhances the comprehensive performance of the coating through thermomechanical coupling and chemical modification; each step works synergistically to form a composite coating with continuous composition transition, which not only retains the toughness of metal materials but also has the anti-adhesion properties of ceramic materials.

[0072] Through the above technical solution, this application effectively solves the problem that the inner wall of the ball mill is prone to cracks under high-intensity impact, while significantly reducing the amount of adhesion of fine powder during the processing process; the pretreatment process ensures the reliable bonding of the coating and the substrate, the gradient deposition structure alleviates the stress concentration caused by the difference in thermal expansion coefficient, and the passivation and sealing treatment forms a stable surface chemical state, ultimately achieving the extension of the equipment's continuous operation cycle and the reduction of maintenance costs.

[0073] In one embodiment, in step S1, the mechanical polishing is performed using a planetary grinder, using 400#, 800#, and 1200# diamond abrasives in sequence to grade and polish the inner wall of the ball mill until the surface roughness Ra is less than or equal to 0.8 μm.

[0074] The electrochemical degreasing adopts an alkaline solution containing 50g / L NaOH and 30g / L Na3PO4 at 60-80℃ and 2-3A / dm 2 Current density electrolysis treatment for 15-20min;

[0075] The electrolytic polishing is performed using a mixed electrolyte of phosphoric acid and sulfuric acid in a volume ratio of 3:1 at a voltage of 12-15V until the surface roughness Ra of the inner wall of the ball mill is less than or equal to 0.2 μm;

[0076] The acid washing and activation is carried out by soaking in a 10% HCl+5% HF mixed acid solution at room temperature for 30-60 seconds.

[0077] In this embodiment, the planetary grinder refers to a surface treatment device with a multi-axis synchronous rotation function, which can be specifically implemented by a three-axis linkage planetary grinding head, eliminating unidirectional grinding marks through multi-directional motion; wherein, the NaOH and Na3PO4 composite system in the alkaline solution refers to the synergistic effect of two strong alkaline substances, which can be specifically achieved by saponifying grease with NaOH and dispersing dirt with Na3PO4, forming a dual action mechanism of electrolytic degreasing; wherein, the mixed electrolyte with a volume ratio of phosphoric acid to sulfuric acid of 3:1 refers to a specific ratio of two strong oxidizing acids, which can specifically form a dynamic balance through the passivation effect of phosphoric acid and the dissolution effect of sulfuric acid to achieve selective removal of surface micro-protrusions; wherein, the 10% HCl + 5% HF mixed acid solution refers to a composite activation system containing chloride ions and fluoride ions, which can be specifically achieved through Cl - Remove oxide film, F - The etching of the metal substrate works in tandem to expose a fresh metal surface.

[0078] Specifically, the multi-directional grinding mode of the planetary grinder can eliminate the surface anisotropy caused by single-direction grinding. For example, after rough grinding with 400# abrasive, 800# abrasive can eliminate the macro scratches formed by 400#, and 1200# abrasive further refines the surface texture. During the electrolysis process, the alkaline solution produces the coordinated migration of hydroxide ions and sodium ions. For example, the oxygen evolution reaction at the anode promotes the emulsification of oils and fats, and the hydrogen evolution reaction at the cathode enhances surface scouring. The mixed electrolyte of phosphoric acid and sulfuric acid forms a gradient concentration field under the action of the electric field. For example, phosphoric acid forms a passivation film on the metal surface to inhibit excessive corrosion, while sulfuric acid preferentially dissolves the weak areas of the passivation film to achieve selective polishing. The fluoride ions in the mixed acid solution can preferentially react with the base metal. For example, HF and Al elements generate soluble fluoroaluminates, which simultaneously remove the surface aluminum oxide layer.

[0079] Through the above technical scheme, this application effectively controls the surface pretreatment quality of the substrate, so that the bonding strength between the subsequent coating and the substrate is increased to more than 45MPa, and the porosity is reduced to less than 0.5%; the step-by-step optimization of the surface roughness improves the uniformity of the stress distribution of the coating, and the Ra value after electrolytic polishing reaches 0.15μm level; the composite pickling process increases the active site density on the substrate surface by 2-3 times, providing a uniform nucleation base for subsequent coating deposition; the overall optimization of the pretreatment process improves the anti-powder adhesion performance of the coating by 40%, and the continuous operation cycle of the equipment is extended to more than 1200 hours.

[0080] In one embodiment, in step S2, the deposition working voltage is 32-36V, the deposition working current is 150-200A, the deposition spraying distance is 150-200mm, the deposition powder feeding rate is 30-50g / min, the purity of the Ar protective gas is greater than or equal to 99.99%, the thickness of the pre-electroplating layer is 100-200μm, the grain size is 20-50nm, and the porosity is less than or equal to 0.2%.

[0081] In this embodiment, the Al-Ti-V-Zr-Cr-Mo multi-principal alloy powder refers to a composite metal powder prepared according to a specific atomic ratio, which can be specifically achieved by using spherical alloy powder prepared by a gas atomization method, and its particle size distribution is controlled in the range of 45-75 μm; the arc spraying equipment can be specifically achieved by using a high-energy plasma spraying system with closed-loop control of the powder feeding rate to ensure the precise deposition of the alloy elements; the Ar protective gas can be specifically achieved by using high-purity argon gas that has been subjected to secondary purification treatment with a molecular sieve, and its oxygen content is controlled below 10 ppm.

[0082] Specifically, during the preparation of the pre-electroplating layer, by precisely controlling the arc voltage within the range of 32-36V, for example, using an intermediate value of 34V, a stable plasma arc state can be maintained; at the same time, the spraying current is controlled within the range of 150-200A, for example, using an intermediate value of 180A, to ensure sufficient melting of the alloy powder; the spraying distance is controlled within the range of 150-200mm, for example, through real-time monitoring with a laser rangefinder, to optimize the deposition state of the molten droplet; the powder feeding rate is controlled within the range of 30-50g / min, for example, using an intermediate value of 40g / min, to achieve a balance between the deposition rate and the coating quality.

[0083] In some specific embodiments, the spraying process may adopt a cross-spraying path, for example, spraying in the axial direction first and then in the circumferential direction, to ensure uniformity of coating thickness; the substrate preheating temperature may be controlled within the range of 80-120°C, for example, an intermediate value of 100°C may be adopted to reduce stress within the coating; interlayer cooling may adopt compressed air forced cooling, for example, keeping the interlayer temperature no more than 150°C to prevent overheating and deformation of the substrate.

[0084] Through the above-mentioned technical solution, this application achieves dense deposition of a multi-element alloy coating, effectively controlling the porosity to below 0.2%, thereby ensuring the coating's anti-permeability properties. The 20-50nm nanocrystalline structure formed in the coating significantly increases the material's hardness to over HV800. Furthermore, the high-purity Ar protective atmosphere prevents oxidation of alloying elements during high-temperature deposition, ensuring precise control of the coating's composition. The optimized combination of spray process parameters achieves a bond strength exceeding 15MPa between the pre-plated layer and the substrate, providing an ideal transition base for subsequent electroplating layers.

[0085] In one embodiment, in step S3, the electroplating solution includes 50-70 g / L Al(NO3)3·9H2O, 30-50 g / L Ti(SO4)2, 20-30 g / L VOSO4, 15-25 g / L ZrCl4, 40-60 g / L CrCl3, and 30-50 g / L MoO3; the deposition current density is 2-5 A / dm 2 The deposition temperature is 30-40°C, the deposition pH value is 3-5, the deposition time is 90-150min, the thickness of the overall electroplating layer is 300-500μm, and the surface energy is less than or equal to 30mJ / m 2 ;

[0086] The electroplating solution further includes 50-80 g / L of Na2SO4 as a conductive salt and 10-15 g / L of sodium citrate as a buffer.

[0087] In this embodiment, Al(NO3)3·9H2O refers to aluminum nitrate hydrate, which can be specifically achieved by dissolving industrial-grade raw materials with a purity greater than 99% in deionized water, as a supply source of aluminum element; Ti(SO4)2 refers to titanium sulfate, which can be specifically achieved by using a solution prepared by the reaction of sulfuric acid and titanium dioxide, and is used to provide the ionic form of titanium element. VOSO4 refers to vanadium oxysulfate, which can be specifically achieved by using blue crystals generated by the reaction of vanadium oxide and sulfuric acid, and is used as an electrodeposition precursor for the vanadium element; ZrCl4 refers to zirconium tetrachloride, which can be specifically achieved by dissolving anhydrous zirconium chloride powder in an acidic medium, and is used to form zirconium complex ions; CrCl3 refers to chromium trichloride, which can be specifically achieved by using a solution of electrolytic chromium plates dissolved in hydrochloric acid, and is used as a source of chromium element; MoO3 refers to molybdenum trioxide, which can be specifically achieved by dissolving the thermal decomposition product of ammonium molybdate in an acidic electrolyte, and is used to provide molybdate ions; Na2SO4 is used as a conductive salt, which can be specifically achieved by directly adding analytically pure anhydrous sodium sulfate to the plating solution, and is used to improve the conductivity of the electrolyte; sodium citrate is used as a buffer, which can be specifically achieved by using salts generated by the neutralization reaction of citric acid and sodium hydroxide, and is used to maintain the stability of the pH value of the electrolyte.

[0088] Specifically, during the preparation of the electroplating solution, by precisely controlling the concentration ratio of each metal salt, for example, controlling Al(NO3)3·9H2O within the range of 50-70g / L, the solid solution strengthening effect of the aluminum element in the coating can be ensured; at the same time, using Ti(SO4)2 and VOSO4 in a specific ratio, for example, Ti(SO4)2 is 30-50g / L and VOSO4 is 20-30g / L, can promote the in-situ formation of titanium-vanadium composite oxides; during the deposition process, the current density is controlled at 2-5A / dm 2 range, for example, adopting a segmented increasing current mode can avoid the burning of the coating edge due to excessive current density; the temperature is controlled within the range of 30-40℃, for example, maintaining the tank temperature through a circulating water cooling system can ensure the dynamic balance between the diffusion rate and deposition rate of metal ions.

[0089] In some specific embodiments, the preparation of the electroplating solution can adopt a step-by-step dissolution method, for example, Na2SO4 and sodium citrate are first dissolved in deionized water to form a base solution, and then metal salts such as Al(NO3)3·9H2O and Ti(SO4)2 are added in sequence and stirred until completely dissolved; a pulse power supply can be used during the deposition process, for example, the on-time is set to 10ms and the off-time is set to 5ms to refine the grain structure of the coating; ultrasonic cleaning can be used in the post-plating treatment stage, for example, treatment at a frequency of 40kHz for 10 minutes to remove impurity ions adsorbed on the surface.

[0090] Through the above technical solution, the present invention can achieve uniform co-deposition of multi-element coatings and effectively reduce the surface energy of the coating to 30mJ / m 2 The following significantly reduces the amount of powder material adhering to the inner wall of the ball mill; the nanocrystalline and amorphous mixed structure formed in the coating can inhibit crack propagation, so that the coating maintains structural integrity under long-term impact loads; at the same time, the sodium citrate buffer system maintains the pH value of the electrolyte stable in the range of 3-5, avoiding the precipitation of hydroxides caused by pH fluctuations of metal ions, and ensuring precise control of the coating composition.

[0091] In one embodiment, a process for preparing an electroplated coating on the inner wall surface of a ball mill is provided, comprising the following steps:

[0092] S1. Matrix pretreatment: The inner wall of the ball mill is subjected to mechanical polishing, electrochemical degreasing, electrolytic polishing and pickling activation treatment in sequence. Mechanical polishing adopts a planetary grinder, and 400#, 800# and 1200# diamond abrasives are used in sequence to grind the inner wall of the ball mill to a surface roughness Ra of 0.75μm. Electrochemical degreasing adopts an alkaline solution containing 50g / L NaOH and 30g / L Na3PO4 at 70℃ and 2.5A / dm 2 The current density was used for electrolytic treatment for 20 minutes. The electrolytic polishing was carried out using a mixed electrolyte of phosphoric acid and sulfuric acid in a volume ratio of 3:1 at a voltage of 15V until the surface roughness Ra of the inner wall of the ball mill was reduced to 0.18μm. The pickling activation was carried out using a 10% HCl + 5% HF mixed acid solution for immersion at room temperature for 45 seconds.

[0093] S2. Preparation of pre-electroplating layer: Using supersonic arc spraying equipment to deposit an Al-Ti-V-Zr-Cr-Mo multi-principal alloy layer on the pretreated substrate surface to form a pre-electroplating layer, wherein the deposition working voltage is 36 V, the deposition working current is 180 A, the deposition spraying distance is 180 mm, the deposition powder feeding rate is 50 g / min, the Ar protective gas purity is 99.99%, the flow rate is 15 L / min, and the pre-electroplating layer has a thickness of 150 μm, a grain size of 35 nm, and a porosity of 0.18%;

[0094] S3. Preparation of the overall electroplating layer: prepare an electroplating solution according to the ratio, and deposit it on the surface of the pre-electroplating layer to form an overall electroplating layer, wherein the electroplating solution includes 60g / L Al(NO3)3·9H2O, 40g / L Ti(SO4)2, 25g / L VOSO4, 20g / L ZrCl4, 50g / L CrCl3, and 40g / L MoO3. The electroplating solution also includes 60g / L Na2SO4 as a conductive salt and 12g / L sodium citrate as a buffer. The deposition current density is 23A / dm 2The deposition temperature is 35 ° C, the deposition pH value is 4, the deposition time is 120 min, the overall electroplating layer thickness is 400 μm, and the surface energy is 28.5 mJ / m 2；

[0095] S4, post-treatment: The coated workpiece obtained after step S3 was heat treated at 280° C. under nitrogen protection for 2.5 hours, mechanically polished with diamond paste, and sequentially subjected to chromate passivation treatment and silane coupling agent sealing treatment, wherein the parameters of the chromate passivation treatment were as follows: chromate concentration of 50 g / L, pH adjusted to 3.5, temperature of 60° C., and treatment time of 30 minutes.

[0096]

[0097] Table 1

[0098] It can be concluded from the data in Table 1 that the electroplated coating on the inner wall of the ball mill prepared in this embodiment exhibits significant advantages in multiple key performance indicators. The coating achieves synergistic optimization of material properties through a unique gradient structure design. The continuous transition zone formed between the pre-electroplated layer and the overall electroplated layer effectively alleviates the interfacial stress concentration problem common in traditional coatings. In actual grinding tests, the coating exhibits excellent anti-adhesion performance, with the powder adhesion rate reduced by 82% compared with that of the traditional stainless steel inner wall. This is mainly due to the in-situ generated nano-scale Al2O3 / TiO2 composite oxide film in the gradient transition layer, whose surface energy is as low as 28.5mJ / m 2 , only 39.6% of that of stainless steel, significantly weakening the van der Waals force between powder particles and the tank wall; in terms of mechanical properties, the coating system exhibits excellent wear resistance through the synergistic strengthening effect of multiple main alloys. ASTM G65 standard wear test shows that its volume loss is only 0.12cm 3 , which is 73.3% lower than that of the stainless steel inner wall. This is attributed to the fine grain strengthening effect brought by the nanocrystalline structure (grain size 35nm) in the pre-electroplating layer and the solid solution strengthening effect of Cr / Mo elements; more importantly, the bonding strength between the coating and the substrate reaches 48MPa, which is 2.4 times that of traditional ceramic coatings. This strong interface bonding ensures the long-term stability of the coating under high-frequency impact conditions, and achieved an excellent performance of 1350 hours without failure in actual continuous operation tests.

[0099] From the perspective of production process, the supersonic arc spraying and electroplating composite process adopted in this embodiment has good parameter controllability; the precise ratio of each component in the electroplating solution formula (such as the synergistic effect of 60g / L Al(NO3)3·9H2O and 40g / L Ti(SO4)2) ensures the uniform co-deposition of metal elements, and the 280°C nitrogen protection heat treatment effectively eliminates the internal stress of the coating, and increases the density of the coating structure to a level with a porosity of less than 0.2%; the diamond grinding and polishing process adopted in the post-processing stage controls the surface roughness to an ultra-smooth state of Ra=0.09μm. This surface morphology feature further reduces the probability of mechanical intercalation of powder particles.

[0100] Overall, this technical solution has successfully solved the long-standing technical contradiction in the field of ball milling equipment, which is the difficulty in balancing the anti-adhesion requirements and mechanical strength requirements, through the triple innovation of material component gradient design, microstructure regulation and process parameter optimization. Its performance advantages are not only reflected in laboratory test data, but also verified in actual production environments, providing reliable equipment guarantee for the precision processing of high-value-added powder materials. The long-life characteristics of the coating (1350 hours of continuous operation) can significantly reduce the frequency of equipment maintenance. Calculated at an annual output of 5000 hours, the number of shutdowns for cleaning can be reduced by 62%. The resulting increase in production efficiency and reduction in energy consumption have significant economic benefits.

[0101] It should be understood that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0102] The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present application, and should all be included in the scope of protection of the present application.

Claims

1. An electroplating coating on the inner wall surface of a ball mill, characterized in that: include: A pre-plating layer located on the inner wall of the ball mill tank and an integral plating layer located on the surface of the pre-plating layer; The atomic percentages of the metal elements in the pre-electroplating layer are: Al: 15-25%, Ti: 15-25%, V: 10-20%, Zr: 10-20%, Cr: 15-25%, Mo: 10-20%; The atomic percentages of the metal elements in the overall electroplating layer are: Al: 20-30%, Ti: 20-30%, V: 10-15%, Zr: 10-15%, Cr: 15-20%, Mo: 10-15%; A gradient transition layer with continuously changing composition is formed between the pre-plating layer and the overall plating layer, and the atomic percentage content of each metal element in the gradient transition layer changes continuously and linearly from the pre-plating layer to the overall plating layer.

2. The electroplated coating on the inner wall surface of a ball mill according to claim 1, characterized in that: The thickness of the pre-electroplating layer is 100-200 μm, and the microhardness thereof is greater than or equal to HV800.

3. The electroplated coating on the inner wall surface of a ball mill according to claim 1, characterized in that: The thickness of the overall electroplating layer is 300-500 μm, and its surface energy is less than or equal to 30 mJ / m 2 .

4. The electroplated coating on the inner wall surface of a ball mill according to claim 1, characterized in that: The thickness of the gradient transition layer is 50-100 μm, and the hardness thereof increases continuously from HV800 to HV1000 in a direction from the pre-plating layer to the overall plating layer.

5. The electroplated coating on the inner wall surface of a ball mill according to claim 1, characterized in that: The overall electroplating layer is prepared by an electroplating process, and its surface roughness Ra is less than or equal to 0.1 μm.

6. The electroplated coating on the inner wall surface of a ball mill according to claim 1, characterized in that: An in-situ Al2O3 / TiO2 composite oxide film is formed in the gradient transition layer, and the film thickness is 5-15nm.

7. A method for preparing an electroplated coating on the inner wall surface of a ball mill, characterized in that: The following steps are involved: S1. Matrix pretreatment: The inner wall of the ball mill is subjected to mechanical polishing, electrochemical degreasing, electrolytic polishing and pickling activation treatment in sequence; S2. Preparation of pre-plating layer: using supersonic arc spraying equipment to deposit an Al-Ti-V-Zr-Cr-Mo multi-principal alloy layer on the pretreated substrate surface to form a pre-plating layer; S3. Preparation of the overall electroplating layer: preparing an electroplating solution according to a ratio, and depositing it on the surface of the pre-electroplating layer to form an overall electroplating layer; S4, post-processing: heat-treating the plated workpiece obtained after step S3 at 250-300° C. under nitrogen protection for 2-3 hours, mechanically polishing with diamond paste, and sequentially performing chromate passivation treatment and silane coupling agent sealing treatment.

8. The method for preparing an electroplated coating on the inner wall surface of a ball mill according to claim 7, characterized in that: In step S1, the mechanical polishing is performed using a planetary grinder, and 400#, 800#, and 1200# diamond abrasives are sequentially used to grade the inner wall of the ball mill until the surface roughness Ra of the inner wall of the ball mill is less than or equal to 0.8 μm; The electrochemical degreasing adopts an alkaline solution containing 50g / L NaOH and 30g / L Na3PO4 at 60-80℃ and 2-3A / dm 2 Current density electrolysis treatment for 15-20min; The electrolytic polishing is performed using a mixed electrolyte of phosphoric acid and sulfuric acid in a volume ratio of 3:1 at a voltage of 12-15V until the surface roughness Ra of the inner wall of the ball mill is less than or equal to 0.2 μm; The acid washing and activation is carried out by soaking in a 10% HCl+5% HF mixed acid solution at room temperature for 30-60 seconds.

9. The method for preparing an electroplated coating on the inner wall surface of a ball mill according to claim 7, characterized in that: In step S2, the deposition working voltage is 32-36V, the deposition working current is 150-200A, the deposition spraying distance is 150-200mm, the deposition powder feeding rate is 30-50g / min, the purity of the Ar protective gas is greater than or equal to 99.99%, the thickness of the pre-electroplating layer is 100-200μm, the grain size is 20-50nm, and the porosity is less than or equal to 0.2%.

10. The method for preparing an electroplated coating on the inner wall surface of a ball mill according to claim 7, characterized in that: In step S3, the electroplating solution includes 50-70 g / L Al(NO3)3·9H2O, 30-50 g / L Ti(SO4)2, 20-30 g / L VOSO4, 15-25 g / L ZrCl4, 40-60 g / L CrCl3, and 30-50 g / L MoO3; the deposition current density is 2-5 A / dm 2 The deposition temperature is 30-40°C, the deposition pH value is 3-5, the deposition time is 90-150min, the thickness of the overall electroplating layer is 300-500μm, and the surface energy is less than or equal to 30mJ / m 2 ; The electroplating solution further includes 50-80 g / L of Na2SO4 as a conductive salt and 10-15 g / L of sodium citrate as a buffer.

Images