Corrosion-resistant coating process for precision parts

Abstract

The invention belongs to the technical field of precision part machining, and discloses a precision part corrosion-resistant coating process, electrochemical treatment is chromic acid treatment, coating materials comprise epoxy resin coating, polyurethane coating and polytetrafluoroethylene coating, and a spraying technology comprises electrostatic spraying, air spraying and airless spraying. Hydrochloric acid is used for removing oxides on the surface of steel, phosphoric acid is used for removing rust on the surface of metal, through cooperation of acid pickling, passivation and electroplating, acid pickling and passivation can remove the surface oxides, the hardness and friction resistance of the surface of the metal can be improved, and electroplating can improve the surface hardness of parts, improve abrasion resistance and prevent corrosion; a protective film is formed through passivation treatment, further oxidation is prevented, chromate passivation soaking time is 10-30 minutes, phosphate passivation soaking time is 5-15 minutes, nitric acid passivation soaking time is 5-10 minutes, and durability, corrosion resistance and surface hardness of the precision part are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of precision parts processing, and in particular relates to a corrosion-resistant coating process for precision parts. Background Art

[0002] Precision parts refer to components with precise size, shape, and structure. They are usually used in high-precision equipment and have strict tolerance requirements. Common precision parts include: shaft parts: motor shafts, drive shafts, rolling bearings, used to transmit power and motion; gears: used to transmit rotational motion; threaded parts: bolts, nuts, screws, used to fix and connect mechanical parts; molds: injection molds, stamping molds, tools for producing various precision parts; precision instrument components: optical elements, lasers and sensors, used for measurement, control and adjustment; pump parts: pump shafts, pump bodies, valves, used for fluid delivery and control; microelectronic components: chips, integrated circuits and connectors, used in electronic equipment, requiring high precision and high reliability. Precision parts are usually exposed to different environmental conditions during use. These environments may contain moisture, chemicals, oxygen, and salt, which may cause corrosion of parts. For this reason, precision parts need to be coated with corrosion-resistant coatings.

[0003] However, the existing corrosion-resistant coating process for precision parts is not perfect and still has certain defects:

[0004] Precision parts are often directly immersed in corrosion-resistant coatings and dried using natural curing. Not only does the waiting time take a long time, but the curing effect is also uneven. Oxides, oil stains, and impurities on the surface of the parts will affect the effect of the coating. Precision parts are exposed to harsh environments for a long time, and the rate of corrosion will accelerate, reducing the service life of the parts. For this reason, a corrosion-resistant coating process for precision parts is designed. Summary of the Invention

[0005] The purpose of the present invention is to provide a corrosion-resistant coating process for precision parts to solve the problem that the natural curing method proposed in the above background technology is used to achieve drying, which not only takes a long time to wait, but also has an uneven curing effect. The oxides, oil stains and impurities on the surface of the parts will affect the effect of the coating. The precision parts are exposed to harsh environments for a long time, and the corrosion rate will be accelerated.

[0006] In order to achieve the above object, the present invention provides the following technical solution: a corrosion-resistant coating process for precision parts, comprising the following coating process steps:

[0007] S1. Parts cleaning and surface treatment

[0008] Degreasing: Use solvents and chemical cleaning agents to remove oil, fingerprints, and dust from the surface of parts;

[0009] Rust removal: If there is rust on the surface of the parts, pickling and sandblasting are usually used to remove the rust;

[0010] Surface roughening: Sanding, sandblasting and electrochemical treatment of the surface to increase surface roughness and provide better adhesion for the coating;

[0011] S2. Surface passivation

[0012] Pickling: Common reagents include hydrochloric acid, phosphoric acid, hydrofluoric acid and oxalic acid. The pickling temperature is 20℃-60℃;

[0013] Passivation: Common reagents include chromate solution, phosphate solution and nitric acid solution. The passivation temperature is 20℃-40℃;

[0014] Electroplating: Common reagents include nickel plating, copper plating, zinc plating, gold plating and silver plating. The temperature of electroplating is 20℃-60℃;

[0015] S3. Coating material preparation

[0016] Coating selection: Choose the appropriate coating material and the appropriate coating according to the working environment of the part;

[0017] Mixing paint: Prepare paint according to requirements;

[0018] S4. Coating application

[0019] Spraying: The coating is sprayed onto the surface of the parts using spraying technology, which is suitable for large-area coating applications;

[0020] Dip coating: immersing the parts in the coating;

[0021] Brush coating: manual and mechanical brush coating, suitable for small batches and local coating;

[0022] S5. Coating curing

[0023] Natural curing: the paint cures on its own at room temperature;

[0024] S6, coating drying

[0025] Bake-and-cure: Place the coated parts in an oven to heat and cure the coating;

[0026] S7. Coating inspection

[0027] Coating thickness detection: Use a coating thickness gauge to detect the thickness of the coating to ensure that the coating is uniform and meets the design requirements;

[0028] Appearance inspection: Check the appearance of the coating to ensure it is uniform and free of bubbles and cracks;

[0029] S8. Coating quality control

[0030] Adhesion test: Use pull-off test and scratch test methods to detect the adhesion between the coating and the substrate;

[0031] Corrosion testing: Expose coated parts to a simulated corrosive environment to evaluate the corrosion resistance of the coating;

[0032] S9, surface polishing

[0033] Surface polishing: Polishing is required to improve surface finish and reduce friction;

[0034] S10, wear-resistant coating treatment

[0035] Wear-resistant coating treatment: If the parts require wear resistance, an additional wear-resistant coating is added on the coating.

[0036] Preferably, the electrochemical treatment is chromic acid treatment, the coating material includes epoxy resin coating, polyurethane coating and polytetrafluoroethylene coating, and the spraying technology includes electrostatic spraying, air spraying and airless spraying.

[0037] Preferably, the hydrochloric acid is used to remove oxides on the surface of steel, phosphoric acid is used to remove rust on the metal surface, hydrofluoric acid is used to remove oxides on the surface of aluminum alloy, and oxalic acid is used to remove oxides on the surface of copper and brass. Ventilation is required during the pickling process to avoid the accumulation of acid vapor, and the pickling tank is made of acid-resistant materials.

[0038] Preferably, the acid-resistant material includes acid-resistant steel, stainless steel and polypropylene, the chromate solution is used for passivation of stainless steel to form a chromium oxide film to provide corrosion resistance, the phosphate solution forms a phosphate protective film to enhance the corrosion resistance of precision parts, and the nitric acid solution is used for passivation of stainless steel to remove surface oxides and form a passivation film.

[0039] Preferably, the electroplating includes an electrolytic cell, a power supply and a part to be electroplated. The electroplating cell is made of stainless steel, glass and polypropylene to prevent the metal solution from corroding the cell body. The electroplating requires the use of a constant DC power supply to control the current density and ensure that the coating is uniform and dense. The concentration of the phosphate passivation solution is between 10-30% (weight percentage), the concentration of the nitric acid passivation solution is between 30-50% (weight percentage), the chromate passivation immersion time is 10-30 minutes, the phosphate passivation immersion time is 5-15 minutes, and the nitric acid passivation immersion time is 5-10 minutes, thereby improving the durability, corrosion resistance and surface hardness of precision parts.

[0040] Preferably, the natural curing temperature is 15°C-30°C, the curing time is 24 hours-7 days, the epoxy resin coating requires curing time of 24 hours-48 hours, the polyurethane coating requires curing time of 3 days, the polyurethane coating baking curing temperature is 160°C-180°C, 15-30 minutes, and the acrylic coating baking curing temperature is 140°C-160°C, 10-15 minutes.

[0041] Preferably, the main materials of the wear-resistant coating are ceramic coating, cemented carbide coating, polyurethane coating, fluorocarbon coating and metal coating.

[0042] The beneficial effects of the present invention are as follows:

[0043] 1. The present invention cooperates with pickling, passivation and electroplating through the arrangement. Pickling and passivation can not only remove surface oxides, but also increase the hardness and anti-friction performance of the metal surface. Electroplating can improve the surface hardness of parts, improve wear resistance, and prevent corrosion. A protective film is formed by passivation to prevent further oxidation. Electroplating can form a protective metal coating on the surface of the part to prevent oxidation and corrosion. Electroplating requires the use of a constant DC power supply to control the current density to ensure that the coating is uniform and dense. The concentration of the phosphate passivation solution is between 10-30% (weight percentage), the concentration of the nitric acid passivation solution is between 30-50% (weight percentage), the chromate passivation immersion time is 10-30 minutes, the phosphate passivation immersion time is 5-15 minutes, and the nitric acid passivation immersion time is 5-10 minutes, thereby improving the durability, corrosion resistance and surface hardness of precision parts.

[0044] 2. The present invention combines acid-resistant materials, chromate solution, phosphate solution and nitric acid solution. The acid-resistant materials include acid-resistant steel, stainless steel and polypropylene. The chromate solution is used for passivation of the stainless steel to form a chromium oxide film to provide corrosion resistance. The phosphate solution forms a phosphate protective film to enhance the corrosion resistance of precision parts. The nitric acid solution is used for passivation of the stainless steel to remove surface oxides and form a passivation film. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 This is a compensation process flow chart of the present invention. DETAILED DESCRIPTION

[0046] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0047] like Figure 1As shown, the embodiment of the present invention provides a technical solution for the corrosion-resistant coating process of precision parts:

[0048] A corrosion-resistant coating process for precision parts includes the following coating process steps:

[0049] S1. Parts cleaning and surface treatment

[0050] Degreasing: Use solvents and chemical cleaning agents to remove oil, fingerprints, and dust from the surface of parts;

[0051] Rust removal: If there is rust on the surface of the parts, pickling and sandblasting are usually used to remove the rust;

[0052] Surface roughening: Sanding, sandblasting and electrochemical treatment of the surface to increase surface roughness and provide better adhesion for the coating;

[0053] S2. Surface passivation

[0054] Pickling: Common reagents include hydrochloric acid, phosphoric acid, hydrofluoric acid and oxalic acid. The pickling temperature is 20℃-60℃;

[0055] Passivation: Common reagents include chromate solution, phosphate solution and nitric acid solution. The passivation temperature is 20℃-40℃;

[0056] Electroplating: Common reagents include nickel plating, copper plating, zinc plating, gold plating and silver plating. The temperature of electroplating is 20℃-60℃;

[0057] S3. Coating material preparation

[0058] Coating selection: Choose the appropriate coating material and the appropriate coating according to the working environment of the part;

[0059] Mixing paint: Prepare paint according to requirements;

[0060] S4. Coating application

[0061] Spraying: The coating is sprayed onto the surface of the parts using spraying technology, which is suitable for large-area coating applications;

[0062] Dip coating: immersing the parts in the coating;

[0063] Brush coating: manual and mechanical brush coating, suitable for small batches and local coating;

[0064] S5. Coating curing

[0065] Natural curing: the paint cures on its own at room temperature;

[0066] S6, coating drying

[0067] Bake-and-cure: Place the coated parts in an oven to heat and cure the coating;

[0068] S7. Coating inspection

[0069] Coating thickness detection: Use a coating thickness gauge to detect the thickness of the coating to ensure that the coating is uniform and meets the design requirements;

[0070] Appearance inspection: Check the appearance of the coating to ensure it is uniform and free of bubbles and cracks;

[0071] S8. Coating quality control

[0072] Adhesion test: Use pull-off test and scratch test methods to detect the adhesion between the coating and the substrate;

[0073] Corrosion testing: Expose coated parts to a simulated corrosive environment to evaluate the corrosion resistance of the coating;

[0074] S9, surface polishing

[0075] Surface polishing: Polishing is required to improve surface finish and reduce friction;

[0076] S10, wear-resistant coating treatment

[0077] Wear-resistant coating treatment: If the parts require wear resistance, an additional wear-resistant coating is added on the coating.

[0078] Among them, the electrochemical treatment is chromic acid treatment, the coating materials include epoxy resin coating, polyurethane coating and polytetrafluoroethylene coating, the spraying technology includes electrostatic spraying, air spraying and airless spraying, hydrochloric acid is used to remove oxides on the surface of steel, phosphoric acid is used to remove rust on the metal surface, hydrofluoric acid is used to remove oxides on the surface of aluminum alloy, oxalic acid is used to remove oxides on the surface of copper and brass, and ventilation is required during the pickling process to avoid the accumulation of acid vapor. The pickling tank is made of acid-resistant materials, including acid-resistant steel, stainless steel and polypropylene. Chromate solution is used for passivation of stainless steel to form a chromium oxide film and provide corrosion resistance. Phosphate solution forms a phosphate protective film to enhance the corrosion resistance of precision parts. Nitric acid solution is used for passivation of stainless steel to remove surface oxides and form a passivation film.

[0079] Among them, electroplating includes an electrolytic cell, a power supply and parts to be electroplated. The electroplating cell is made of stainless steel, glass and polypropylene materials to prevent the metal solution from corroding the cell body. Electroplating requires a constant DC power supply to control the current density and ensure that the coating is uniform and dense. The concentration of the phosphate passivation solution is between 10-30% (weight percentage), and the concentration of the nitric acid passivation solution is between 30-50% (weight percentage). The chromate passivation immersion time is 10-30 minutes, the phosphate passivation immersion time is 5-15 minutes, and the nitric acid passivation immersion time is 5-10 minutes, thereby improving the durability, corrosion resistance and surface hardness of precision parts. The natural curing temperature is between 15°C and 30°C, and the curing time is 24 hours to 7 days. The epoxy resin coating requires a curing time of 24 hours to 48 hours, and the polyurethane coating requires a curing time of 3 days. The polyurethane coating baking curing temperature is 160°C to 180°C, 15-30 minutes, and the acrylic coating baking curing temperature is 140°C to 160°C, 10-15 minutes.

[0080] Working principle and use process of the present invention: Precision parts refer to parts with precise size, shape and structure, which are usually used in high-precision equipment and have strict tolerance requirements. Common precision parts include: shaft parts: motor shafts, transmission shafts, rolling bearings, used to transmit power and motion; gears: used to transmit rotational motion; threaded parts: bolts, nuts, screws, used to fix and connect mechanical parts; molds: injection molds, stamping molds, tools for producing various precision parts; precision instrument parts: optical elements, lasers and sensors, used for measurement, control and regulation; pump parts: pump shafts, pump bodies, valves, used for flow Fluid transportation and control; microelectronic components: chips, integrated circuits and connectors, used in electronic equipment, require high precision and high reliability. Precision parts are usually exposed to different environmental conditions during use. These environments may contain moisture, chemicals, oxygen, and salt, which may cause corrosion of parts. For this reason, precision parts need to be coated with corrosion-resistant coatings. Precision parts are often directly immersed in corrosion-resistant coatings and dried by natural curing. Not only does the waiting time take a long time, but the curing effect is not uniform. Oxides, oil stains and impurities on the surface of the parts will affect the effect of the coating. Precision parts are exposed to harsh environments. If the exposure time is long, the corrosion rate will accelerate, which will reduce the service life of the parts. Therefore, a corrosion-resistant coating process for precision parts is designed. Parts cleaning and surface treatment include degreasing: using solvents and chemical cleaning agents to remove oil, fingerprints, and dust on the surface of parts; rust removal: if there is rust on the surface of parts, acid pickling and sandblasting are usually used to remove rust; surface roughening: sanding, sandblasting and electrochemical treatment are performed on the surface to increase the surface roughness, provide better adhesion for the coating, surface passivation, select suitable coating materials, select suitable coatings according to the working environment of the parts, prepare coatings according to requirements, and use spraying technology to spray the coatings onto the parts. Parts surface, suitable for large-area coating application; manual and mechanical brushing, suitable for small batch and local coating; put the coated parts into the oven for heating to cure the coating; coating thickness detection: use a coating thickness gauge to detect the thickness of the coating to ensure that the coating is uniform and meets the design requirements; appearance inspection: check the appearance of the coating for uniformity, bubbles, cracks and defects; adhesion test: use pull-off test and scratch test methods to detect the adhesion between the coating and the substrate; corrosion test: expose the coated parts to a simulated corrosion environment to evaluate the corrosion resistance of the coating and surface polishing: polishing is required to improve the surface finish and reduce friction.

[0081] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A corrosion-resistant coating process for precision parts, comprising the following coating process steps: S1. Parts cleaning and surface treatment Degreasing: Use solvents and chemical cleaning agents to remove oil, fingerprints, and dust from the surface of parts; Rust removal: If there is rust on the surface of the parts, pickling and sandblasting are usually used to remove the rust; Surface roughening: Sanding, sandblasting and electrochemical treatment of the surface to increase surface roughness and provide better adhesion for the coating; S2. Surface passivation Pickling: Common reagents include hydrochloric acid, phosphoric acid, hydrofluoric acid and oxalic acid. The pickling temperature is 20℃-60℃; Passivation: Common reagents include chromate solution, phosphate solution and nitric acid solution. The passivation temperature is 20℃-40℃; Electroplating: Common reagents include nickel plating, copper plating, zinc plating, gold plating and silver plating. The temperature of electroplating is 20℃-60℃; S3. Coating material preparation Coating selection: Choose the appropriate coating material and the appropriate coating according to the working environment of the part; Mixing paint: Prepare paint according to requirements; S4. Coating application Spraying: The coating is sprayed onto the surface of the parts using spraying technology, which is suitable for large-area coating applications; Dip coating: immersing the parts in the coating; Brush coating: manual and mechanical brush coating, suitable for small batches and local coating; S5. Coating curing Natural curing: the paint cures on its own at room temperature; S6, coating drying Bake-and-cure: Place the coated parts in an oven to heat and cure the coating; S7. Coating inspection Coating thickness detection: Use a coating thickness gauge to detect the thickness of the coating to ensure that the coating is uniform and meets the design requirements; Appearance inspection: Check the appearance of the coating to ensure it is uniform and free of bubbles and cracks; S8. Coating quality control Adhesion test: Use pull-off test and scratch test methods to detect the adhesion between the coating and the substrate; Corrosion testing: Expose coated parts to a simulated corrosive environment to evaluate the corrosion resistance of the coating; S9, surface polishing Surface polishing: Polishing is required to improve surface finish and reduce friction; S10, wear-resistant coating treatment Wear-resistant coating treatment: If the parts require wear resistance, an additional wear-resistant coating is added on the coating.

2. A corrosion-resistant coating process for precision parts according to claim 1, characterized in that: The electrochemical treatment is chromic acid treatment, the coating materials include epoxy resin coating, polyurethane coating and polytetrafluoroethylene coating, and the spraying technology includes electrostatic spraying, air spraying and airless spraying.

3. A corrosion-resistant coating process for precision parts according to claim 1, characterized in that: The hydrochloric acid is used to remove oxides on the surface of steel, phosphoric acid is used to remove rust on the metal surface, hydrofluoric acid is used to remove oxides on the surface of aluminum alloy, and oxalic acid is used to remove oxides on the surface of copper and brass. Ventilation is required during the pickling process to avoid the accumulation of acid vapor, and the pickling tank is made of acid-resistant materials.

4. A corrosion-resistant coating process for precision parts according to claim 3, characterized in that: The acid-resistant materials include acid-resistant steel, stainless steel and polypropylene. The chromate solution is used for passivation of stainless steel to form a chromium oxide film to provide corrosion resistance. The phosphate solution forms a phosphate protective film to enhance the corrosion resistance of precision parts. The nitric acid solution is used for passivation of stainless steel to remove surface oxides and form a passivation film.

5. A corrosion-resistant coating process for precision parts according to claim 4, characterized in that: The electroplating process includes an electrolytic cell, a power supply, and parts to be electroplated. The electroplating cell is made of stainless steel, glass, and polypropylene to prevent corrosion of the cell body by the metal solution. A constant DC power supply is required for electroplating to control the current density and ensure a uniform and dense coating. The concentration of the phosphate passivation solution is between 10-30% (weight percentage), the concentration of the nitric acid passivation solution is between 30-50% (weight percentage), the chromate passivation immersion time is 10-30 minutes, the phosphate passivation immersion time is 5-15 minutes, and the nitric acid passivation immersion time is 5-10 minutes, thereby improving the durability, corrosion resistance, and surface hardness of precision parts.

6. The corrosion-resistant coating process for precision parts according to claim 1, characterized in that: The natural curing temperature is 15°C-30°C, and the curing time is 24 hours-7 days. The epoxy resin coating needs to be cured for 24 hours-48 hours, and the polyurethane coating needs to be cured for 3 days. The polyurethane coating baking curing temperature is 160°C-180°C, 15-30 minutes, and the acrylic coating baking curing temperature is 140°C-160°C, 10-15 minutes.

7. The corrosion-resistant coating process for precision parts according to claim 1, characterized in that: The main materials of the wear-resistant coating include ceramic coating, hard alloy coating, polyurethane coating, fluorocarbon coating and metal coating.

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