Pickling passivation coating process

Abstract

The invention relates to a pickling, passivating and coating process, which is used for processing stainless steel products or parts, and comprises the following steps of: a, polishing; b, hot water washing; c, pre-degreasing; d, main degreasing; e, washing with water; f, washing; g, pickling; h, washing; i, washing; j, passivating; k, washing; l, washing; m, electrophoresis; n, performing ultrafiltration cleaning I; o, performing ultrafiltration cleaning II; p, washing; q, baking; r, powder spraying; and s, baking. The technical problem that the adhesive force between a stainless steel material and a composite coating is insufficient can be effectively solved, a GMW14829 test shows that the water boiling cross-cut meets the 0-1 level, and the requirements of different markets for the stainless steel color and the high adhesive force between the coatings are met.

Description

Technical Field

[0001] The invention relates to a coating process for stainless steel 304, in particular to a pickling and passivation coating process, which is used to improve the high requirement of adhesion between composite coatings. Background Art

[0002] Austenitic 304 stainless steel is a low-magnetic chromium-nickel stainless steel with good corrosion resistance, heat resistance, low-temperature strength and mechanical properties. It is widely used in processing, furniture decoration and food industries. The density of 304 stainless steel is 7.93g / cm 3 , operating temperature -196-800 degrees Celsius, good processing performance, high toughness, referred to as 18 / 8 stainless steel.

[0003] There is a demand for color coating on austenitic 304 stainless steel in the market. After degreasing - pickling - electrophoresis - powder spraying, the adhesion of the paint layer reaches the water-boiling grid ≧ 2 level, which cannot meet the high adhesion requirements. Summary of the invention

[0004] The purpose of the present invention is to provide a pickling passivation coating process, which can effectively solve the technical problem of insufficient adhesion between stainless steel products or parts and coatings, meet the 0-1 level of the GMW14829 test water boiling grid, and meet the needs of different markets for stainless steel color and high adhesion between coatings.

[0005] To solve the above technical problems, the present invention is achieved as follows: A pickling passivation coating process, the processing object of which is a stainless steel or iron product or part, is characterized in that it includes the following steps: a. Grinding; b. Hot water washing; c. Pre-degreasing; d. Main degreasing; e. Water washing; f. Water washing; g. Pickling; h. Water washing; i. Water washing; j. Passivation; k. Water washing; l. Water washing; m. Electrophoresis; n. Ultrafiltration cleaning one; o. Ultrafiltration cleaning two; p. Water washing; q. Baking; r. Powder spraying; s. Baking.

[0006] The pickling passivation coating process is characterized in that the stainless steel or iron products and parts after coating pass the GMW14829 test water boiling grid and meet the 0-1 level.

[0007] The pickling and passivation coating process is characterized in that: In the step c, a strong alkaline degreasing agent and a degreasing activator are used to exert impact force on the outer surface of the product so that grease and stains on the outer surface of the product can be fully cleaned; the operating temperature is 50-60°C, the spraying pressure is 0.15-0.25Mpa, and the time is 120-180s; the degreasing agent and the degreasing activator are provided by Henkel, and the models are 1022R and 1021s.

[0008] The pickling and passivation coating process is characterized in that: In the step d, the product is soaked with a strong alkaline degreasing agent and a degreasing activator and the inner cavity and surface of the product are rinsed with ultrasonic vibration to further remove residual grease; the operating temperature is 50-60°C and the time is 180±10s; the degreasing agent and the degreasing activator are provided by Henkel, and the models are 1022R and 1021s.

[0009] The pickling and passivation coating process is characterized in that: In the step g, special medicine is added, compressed air is introduced for stirring, and the mixture is immersed in acid pickling; the operating temperature is 45-55°C, and the time is 180-300s; the medicine adopts the product model PA51-BF of Wuhan Institute of Material Protection, and its main function is to peel off the passivation layer on the surface of stainless steel, make the surface of stainless steel reactive, and generate compounds during the immersion process of the medicine.

[0010] The pickling and passivation coating process is characterized in that: In the step j, special medicine is added for soaking; the operation temperature is room temperature and the time is 120-180s; the passivation medicine is provided by the Wuhan Institute of Material Protection's phosphorus-free additive 207 / 3, which mainly functions to seal the compounds on the surface of the stainless steel and to extend the effectiveness of the pickling agent.

[0011] The main technical effects of the present invention are: 1. Greatly improves the high adhesion requirements between composite paint layers of stainless steel products or parts after electrophoretic powder coating.

[0012] 2. Further increase the conditions of stainless steel's acid and alkali resistance.

[0013] 3. Improve the singleness of stainless steel appearance color to meet the needs of different colors in different occasions.

[0014] 4. Extend the service life of stainless steel. DETAILED DESCRIPTION

[0015] The present invention discloses a pickling passivation coating process, the processing object of which is a metal product or part such as stainless steel, iron parts, etc. (but not including aluminum products, aluminum alloys, aluminum-magnesium alloys, galvanized parts, etc.), comprising the following steps: a. Grinding: Manual grinding is adopted, using an angle grinder with 80-grit professional sandpaper to grind the surface oxide skin areas of the product welds, burnt areas, welding slag, etc. to remove them cleanly. There are obvious grinding marks on the surface of the product after grinding.

[0016] b. Hot water washing: Use hot water and ultrasonic vibration to wash away the internal and external chips and impurities of the product, preheat the workpiece, and make the product initially clean; the washing temperature is 50-60℃, and the time is 120-180s.

[0017] c. Pre-degreasing: Use strong alkaline degreasing agent and degreasing activator to exert impact force on the outer surface of the product, so that the grease and stains on the outer surface of the product can be fully cleaned; the operating temperature is 50-60℃, the spraying pressure is 0.15-0.25Mpa, and the time is 120-180s. The degreasing agent and degreasing activator are provided by Henkel, and the models are 1022R and 1021s.

[0018] d. Main degreasing: soak the product with a strong alkaline degreasing agent and a degreasing activator and rinse the inner cavity and surface of the product with ultrasonic vibration to further remove the residual grease; the operating temperature is 50-60℃, and the time is 180±10s. The degreasing agent and degreasing activator are provided by Henkel, and the models are 1022R and 1021s.

[0019] e. Water washing: Use industrial clean water to wash away the residual degreasing agent inside and outside the product, and make the water curtain continuous for 60±10s.

[0020] f. Water washing: Use pure water to further clean the possible residual chemicals and alkaline water inside and outside the product. The overflow is normally open and flows back to step e; keep the water washing pH and conductivity within the process range, time: 60±10s.

[0021] g. Pickling: special medicine, introduce compressed air for stirring, soak and pickle; operating temperature 45-55℃, time 180-300s. The medicine adopts the product model PA51-BF of Wuhan Institute of Material Protection, which mainly functions to peel off the chromium-rich and nickel-rich layers on the surface of stainless steel products, making the stainless steel surface reactive, generating iron-containing compounds and bringing out ferrous ions during the immersion process.

[0022] h. Water washing: Use clean water to clean the residual acid inside and outside the product to prevent overflow. The overflow should be kept open for 60±10s.

[0023] i. Water washing: Use pure water spray to further remove the residual chemicals and acidic water inside and outside the product; keep the water washing pH and conductivity within the process range, and the time is 60±10s.

[0024] j. Passivation: Soak in special potion at room temperature for 120-180 seconds. The passivation potion is provided by Wuhan Institute of Material Protection, a phosphorus-free additive 207 / 3, which is mainly used to seal the iron-containing compounds on the surface of stainless steel and prolong the effectiveness of the pickling agent.

[0025] k. Water washing: Use pure water to soak and clean the residual passivation liquid inside and outside the product, with the overflow always open; time 60±10s.

[0026] 1. Water washing: Use pure water to further remove the residual passivation liquid inside and outside the product to ensure that the water quality reaches the process range, the time is 60±10s.

[0027] m. Electrophoresis: Two-component cathode electrophoresis coating, construction voltage low voltage section 80-100V, high voltage section 250-280V, time 180±10s. The electrophoresis uses PPG model 6100 product.

[0028] n. Ultrafiltration cleaning 1: Use ultrafiltration liquid to clean the floating paint on the inner and outer surfaces of the product to improve the recovery rate of electrophoretic paint, the time is 60±10s.

[0029] o. Ultrafiltration cleaning 2: Use ultrafiltration liquid to wash the floating paint on the outer surface of the product to further improve the recovery rate of electrophoretic paint, the time is 60±10s.

[0030] p. Water washing: Use pure water to wash the inner and outer surfaces of the product to ensure that there is no residual paint liquid on the outer surface for 60±10s.

[0031] q. Baking: Curing at a temperature of 170-180°C for 30 minutes.

[0032] r. Powder spraying: Use automatic powder spraying station to ensure that the paint thickness is controlled between 100-135 microns; construction static voltage 40-60KV, current 20-30μA, powder supply 40%-60%, air supply 3.5-4.5Nm 3 / h, sulfide gas pressure 2.5-4.0 bar. The powder is provided by Aksu with the model number of Y30DCC.

[0033] s. Baking: solidify the powder at a workpiece temperature of 19°C for 30 minutes.

[0034] The present invention discloses an application of stainless steel products in electrophoresis and powder coating, which solves the problems of easy shedding of coating, poor adhesion, and single appearance color after coating of existing stainless steel. The film thickness of electrophoretic coating meets the GMW:14671 standard; the powder coating meets the GMW:14664 standard; the water-boiled grid meets the GMW:14829 standard; After the product is naturally cooled off the production line, it is boiled in 100℃ water for 20 minutes, then taken out. After natural cooling, it is cross-cutting. The electrophoretic layer test uses 1mm cross-cutting. The test after powder spraying uses 2mm cross-cutting. The adhesion must reach level 0-1.

[0035] The present invention realizes that after the stainless steel products or parts are pickled in a specific reagent tank, the surface activity of the stainless steel is changed. After passivation, the surface state of the stainless steel is better combined with the electrophoretic powder spraying, resulting in the adhesion between the paint layers meeting the cross-cutting requirements of the GMW:14829 standard.

[0036] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of the present invention. That is, any equivalent changes and modifications made according to the content of the patent application scope of the present invention should be within the technical scope of the present invention.

Claims

1. A pickling passivation coating process, the processing object is a stainless steel or iron product or part, characterized in that: It includes the following steps: a. Polishing; b. Hot water washing; c. Pre-degreasing; d. Main degreasing; e. Water washing; f. Water washing; g. Acid washing; h. Washing; i. Washing; j. Passivation; k. Water washing; 1. Wash with water; m. Electrophoresis; n, ultrafiltration cleaning one; o, ultrafiltration cleaning two; p, water washing; q, baking; r, powder spraying; s, baking.

2. The pickling and passivation coating process according to claim 1 is characterized in that : Painted stainless steel or iron products and parts pass the GMW14829 test and meet the 0-1 level.

3. The pickling passivation coating process according to claim 1 or 2, characterized in that : In the step c, a strong alkaline degreasing agent and a degreasing activator are used to exert impact force on the outer surface of the product so that grease and stains on the outer surface of the product can be fully cleaned; the operating temperature is 50-60°C, the spraying pressure is 0.15-0.25Mpa, and the time is 120-180s; the degreasing agent and the degreasing activator are provided by Henkel, and the models are 7506 and 1021s.

4. The pickling passivation coating process according to claim 1 or 2, characterized in that : In the step d, the product is soaked with a strong alkaline degreasing agent and a degreasing activator and the inner cavity and surface of the product are rinsed with ultrasonic vibration to further remove residual grease; the operating temperature is 50-60°C and the time is 180±10s; the degreasing agent and the degreasing activator are provided by Henkel, and the models are 7506 and 1021s.

5. The pickling passivation coating process according to claim 1 or 2, characterized in that : In the step g, special medicine is added, compressed air is introduced for stirring, and the mixture is immersed in acid pickling; the operating temperature is 38-45°C, and the time is 180-300s; the medicine adopts the product model PA51-BF of Wuhan Institute of Material Protection, and its main function is to peel off the passivation layer on the surface of stainless steel, make the surface of stainless steel reactive, and generate compounds during the immersion process of the medicine.

6. The pickling passivation coating process according to claim 1 or 2, characterized in that : In the step j, special medicine is added for soaking; the operation temperature is room temperature and the time is 120-180s; the passivation medicine is provided by the Wuhan Institute of Material Protection's phosphorus-free additive 207 / 3, which mainly functions to seal the compounds on the surface of the stainless steel.