CN116024623A - Black chrome plating process for tailpipe - Google Patents

Abstract

The invention belongs to the technical field of electroplating of stainless steel substrates, and discloses a black chromium plating process for a tailpipe, comprising the following steps: wax removal by hot dipping; wax removal by ultrasonic waves; oil removal by hot dipping; anode electrolysis; acid electrolysis; impact nickel plating; activation ; Semi-bright nickel plating; pearl nickel plating, the bath composition of pearl nickel plating is as follows: nickel sulfate concentration 400-440g/L, nickel chloride concentration 35-45g/L, boric acid concentration 51-55g/L, PH:3.9 ‑4.3; electroplating time 15‑25 minutes, bath temperature 61‑65 ℃; current density 3‑6A/dm2; nickel seal; black chrome plating; hot water washing; hanging; drying; packaging. The present invention replaces the traditional bright nickel plating process with the pearl nickel plating process, improves the appearance defects on the blank, such as pits and pits, and increases the binding force of subsequent black chrome plating.

Description

Black chrome plating process for tailpipe

technical field

The invention belongs to the technical field of electroplating of stainless steel substrates, in particular to a black chromium plating process for a tailpipe.

Background technique

The traditional process of electroplating on stainless steel substrates is to electroplate bright nickel on stainless steel substrates and then plate hexavalent black chromium. The appearance of black chromium plating on the product ranges from black to gray, and the bright nickel area has poor positioning, and there are low-area missing plating defects. , There will be pitting, pits and other appearance defects on the blank. Functional test, binding force test, after 600° high-temperature baking, there are bubble defects, and the finished product is not wear-resistant enough.

Existing CN107557829A a kind of trivalent black chromium plating pearl nickel electroplating process, its post-treatment specific process is pre-nickel plating, light copper, acid activation, semi-bright nickel plating, pearl nickel plating, nickel seal, trivalent black chrome plating , electrolytic purification, and hot water washing, but it uses trivalent black chrome plating, which is not wear-resistant after electroplating.

For this reason, need a kind of new technical scheme to solve above-mentioned technical problem.

Contents of the invention

The technical problem to be solved by the present invention is to provide a black chromium plating process for tailpipes that improves the appearance defects on the blank, increases the binding force of subsequent black chrome plating, increases the wear resistance of the stainless steel substrate, and shortens the plating time.

In order to solve the above technical problems, the present invention provides tailpipe fog-plating black chrome process, tailpipe fog-plated black chrome process, comprising the following steps:

Step 1, hot dip wax removal;

Step 2. Ultrasonic wax removal;

Step 3, hot dip degreasing;

Step 4, anode electrolysis;

Step 5, acid electrolysis;

Step 6, impact nickel plating;

Step 7, activation;

Step 8, semi-bright nickel plating;

Step 9: Pearl nickel plating;

The bath composition of described pearl nickel plating is as follows: nickel sulfate concentration 400-440g/L, nickel chloride concentration 35-45g/L, boric acid concentration 51-55g/L, pH:3.9-4.3; Electroplating time is 15- For 25 minutes, the bath temperature is 61-65°C; the current density is 3-6A/dm2;

Step 10: Nickel seal;

Step 11: black chrome plating;

The bath composition of described black chromium plating is as follows: chromic anhydride concentration 427-472g/L, trivalent chromium concentration 3.7-15g/L; Electroplating time is 5-10 minutes, bath temperature is 13-24 ℃; 20-40A/dm2;

Step 12, hot water washing;

Step 13, hanging down;

Step 14, drying;

Step 15, packing.

Further, in step 2, the ultrasonic wax removal is to soak the workpiece in the wax removal water with a concentration of 10-30ml/L, the soaking time is 5-10 minutes, the temperature of the wax removal liquid is 60-90°C, and the ultrasonic hertz power is 20kHz- 30kHz.

Further, in step 4, the anode electrolysis is to immerse the workpiece in a degreasing solution with a concentration of 30-90g/L, the electrolysis time is 6-10 minutes, the temperature of the degreasing solution is 50-70°C; the current density is 4-10A /dm2.

Further, in step 6, the bath composition of impact nickel plating is as follows: hydrochloric acid concentration 40-60ml/L, nickel chloride concentration 280-350g/L, electrolysis time is 6-10 minutes, current density is 1-3A/L dm2.

Further, in step 8, the bath composition of semi-bright nickel plating is as follows: nickel sulfate concentration 280-320g/L, nickel chloride concentration 40-50g/L, boric acid concentration 40-50g/L, pH: 3.4-3.6 ; Plating time: 25-35 minutes, bath temperature: 58-65 ° C; current density: 1-3A/dm2.

Further, in step 10, the bath composition of nickel seal is as follows: nickel sulfate concentration 230-250g/L, nickel chloride concentration 60-80g/L, boric acid concentration 30-35g/L, PH:4.4-4.9; The time is 5-10 minutes, the bath temperature is 61-65°C; the current density is 2-5A/dm2.

Further, in step 12, during the hot water washing, the workpiece is moved to a hot water bath with a temperature of 65-80° C., and the hot water washing time is 6-10 minutes.

Compared with the prior art, the present invention has the following beneficial effects:

1. The present invention replaces the traditional bright nickel coating process with the pearl nickel coating process to improve the appearance defects on the blank, such as pits and pits. The color of the pearl nickel plating is uniform and white, and it is not easy to leave fingerprints and black spots. When the thickness of the pearl nickel plating reaches 10 microns, it can be plated with an appearance close to the effect of stainless steel, titanium or aluminum. And the pearl nickel plating layer is easy to chrome-plate, which increases the binding force of subsequent black chrome plating.

2. The present invention cancels the base coating of acid copper, and directly plating semi-bright nickel after activation, which shortens the plating time and increases the production capacity by 26.4%.

3. The black matt produced by the fog black chrome plating process of the present invention is superior to the traditional bright black chrome plating in terms of visual perception, uniform and clear in color, and more metallic. The coating has no bubbles or flakes after the function test binding force test is baked at 600° high temperature The shape falls off, which improves the wear resistance of the stainless steel substrate. After black chrome plating, it can be polished. The salt spray acid test (CASS) can reach 72H hours, which is 9% higher than the usual requirement of 66H.

Description of drawings

Fig. 1 is process flow chart of the present invention.

Figure 2 is a flow chart of the traditional electroplating process for stainless steel substrates.

Fig. 3 is a diagram of the electroplating effect of the present invention.

Figure 4 is a traditional bright nickel plating effect diagram of black chromium plating.

Detailed ways

Special tooling hangers are designed for products; under the guarantee of the maximum loading capacity, the current distribution in the high and low areas of the parts is guaranteed to be evenly deposited, and then the qualified coating can be obtained according to the technical requirements of the parts. Put the workpiece on the special hanger in advance, and wait for electroplating.

As shown in Figure 1, the black chromium plating process for the tailpipe includes the following steps:

Step 1. Hot-dipping to remove wax; soak the workpiece in wax-removing water with a concentration of 50-150ml/L. The soaking time is 10-20 minutes, and the temperature of the wax-removing liquid is 60-90°C. It is used to remove the organic wax paste left by the upstream process on the surface of the workpiece.

Step 2. Ultrasonic wax removal: soak the workpiece in wax removal water with a concentration of 10-30ml/L for 5-10 minutes, the temperature of the wax removal liquid is 60-90°C, and the ultrasonic hertz power is 20kHz-30kHz. It is used to strengthen the cleaning of small particle dirt in the inner hole of the workpiece and the arc-shaped deep recess.

Step 3. Degreasing by hot dipping: Soak the workpiece in a degreasing solution with a concentration of 30-90g/L. The soaking time is 6-10 minutes, and the temperature of the degreasing solution is 50-70°C. It is beneficial to emulsify and remove various oil stains on the surface of the workpiece.

Step 4. Anodic electrolysis: soak the workpiece in a degreasing solution with a concentration of 30-90g/L. The electrolysis time is 6-10 minutes, and the temperature of the degreasing solution is 50-70°C. The current density is: 4-10A/dm2. Effectively strip off organic oil stains on workpieces.

Step 5. Acid electrolysis: transfer the workpiece to a hydrochloric acid bath with a concentration of 300-400ml/L, the electrolysis time is 6-10 minutes, and the temperature is normal temperature without heating. The current density is: 1-3A/dm2. Effectively neutralize the residual alkali solution in the previous process and activate the surface of the workpiece.

Step 6, impact nickel plating: the workpiece is transferred to the impact nickel plating bath, the impact nickel plating bath components: hydrochloric acid concentration 40-60ml/L, nickel chloride concentration 280-350g/L, electrolysis time: 6- 10 minutes without heating. The current density is: 1-3A/dm2. Plating a layer of functional nickel layer on the surface of stainless steel which is easy to be passivated, as a base layer for the subsequent process.

Step 7. Activation: Transfer the workpiece to a sulfuric acid activation bath with a concentration of 40-60ml/L, soaking time: 10-20 seconds, without heating, and effectively inhibit the passivation of the basic nickel layer.

Step 8, semi-bright nickel plating: move the workpiece to the semi-bright nickel plating bath, the components of the semi-bright nickel plating bath: nickel sulfate concentration 280-320g/L, nickel chloride concentration 40-50g/L, boric acid concentration 40-50g/L, pH: 3.4-3.6. Electroplating time: 25-35 minutes, bath temperature: 58-65°C. The current density is: 1-3A/dm2. Electroplate the corresponding thickness according to the need to ensure that the subsequent tests are passed. After semi-bright nickel plating, the workpiece has excellent leveling properties, good flexibility, no sulfur in the coating, low stress, and good corrosion resistance in combination with multi-layer nickel.

Step 9, pearl nickel plating: move the workpiece to the pearl nickel plating bath, the pearl nickel plating bath components: nickel sulfate concentration 400-440g/L, nickel chloride concentration 35-45g/L, boric acid concentration 51-55g /L, pH: 3.9-4.3. Electroplating time: 15-25 minutes, bath temperature: 61-65°C. The current density is: 3-6A/dm2. Application of slotting additives: pearl nickel plating p1: 6 ml/L, p2: 15 ml/L, sand agent AF6: 0.25 ml/L. The workpiece is plated with a pearly satin electroplated nickel layer, and the corresponding thickness is electroplated according to the needs to ensure that it passes the subsequent tests.

Step 10, nickel sealing: move the workpiece to the nickel sealing bath solution, the components of the nickel sealing bath solution: nickel sulfate concentration 230-250g/L, nickel chloride concentration 60-80g/L, boric acid concentration 30-35g/L, pH: 4.4-4.9. Electroplating time: 5-10 minutes, bath temperature: 61-65°C. The current density is: 2-5A/dm2. The nickel seal electroplating process contains a certain amount of non-conductive particles, and a thin (1.0-2.5 micron) nickel seal layer is plated on the pearl nickel plating layer, which greatly improves the corrosion resistance.

Step 11, black chromium plating: move the workpiece to the black chromium plating bath, the black chromium plating bath composition: chromic anhydride concentration 427-472g/L, trivalent chromium concentration 3.7-15g/L, electroplating time: 5 -10 minutes, bath temperature: 13-24 ℃. The current density is: 20-40A/dm2. The surface of the workpiece is covered with a black coating composed of chromium and its oxides through hexavalent black chromium plating. The coating has excellent wear resistance and corrosion resistance. After the hexavalent black chromium plating is electroplated, it can be polished, and the coating has excellent adhesion. , Black chrome plating has good thermal stability and can be used in high temperature areas. Using black chrome plating to replace ordinary chrome plating can reduce reflectivity by up to 94%.

Step 12, hot water washing: move the workpiece to a hot water tank with a temperature of 65-80°C for 6-10 minutes. Clean off the residual electroplating bath liquid on the surface of the workpiece, and heat and cure the black chromium plating film layer.

Step 13, Lower hanging: Remove the workpieces from the hanger, place the turnover baskets one by one, and wait for the kind and dry treatment.

Step 14. Drying: Put the workpiece into the drying tunnel for drying, so that there is no water stain on the surface of the workpiece.

Step 15. Packing: inspect and pack according to the customer's requirements.

Embodiment 1, tailpipe mist plating black chrome process, comprises the steps:

Put the workpiece on the special hanger in advance, and wait for electroplating.

Step 1. Hot-dipping to remove wax; soak the workpiece in wax-removing water with a concentration of 50ml/L. The soaking time is: 10 minutes, and the temperature of the wax-removing liquid is: 70°C.

Step 2. Ultrasonic wax removal: soak the workpiece in wax removal water with a concentration of 15ml/L for 6 minutes, the temperature of the wax removal liquid is 60°C, and the ultrasonic hertz power is 20kHz.

Step 3, hot dip degreasing: soak the workpiece in a degreasing solution with a concentration of 35g/L, the soaking time is 6 minutes, and the temperature of the degreasing solution is 50°C.

Step 4, anode electrolysis: soak the workpiece in a degreasing solution with a concentration of 30g/L, the electrolysis time is 6 minutes, and the temperature of the degreasing solution is 50°C. The current density is: 4A/dm2. The purpose is to remove organic oil stains on glass workpieces.

Step 5. Acid electrolysis: transfer the workpiece to a hydrochloric acid bath with a concentration of 300ml/L, the electrolysis time is 6 minutes, and the temperature is normal temperature without heating. The current density is: 1A/dm2.

Step 6, impact nickel plating: transfer the workpiece to the impact nickel plating bath, the impact nickel plating bath components: hydrochloric acid concentration 40ml/L, nickel chloride concentration 280g/L, electrolysis time: 6 minutes, without heating . The current density is: 1A/dm2.

Step 7. Activation: Transfer the workpiece to a sulfuric acid activation bath with a concentration of 40ml/L, soaking time: 10 seconds. No heating required.

Step 8, semi-bright nickel plating: the workpiece is moved to the semi-bright nickel bath, the semi-bright nickel bath components: nickel sulfate concentration 280g/L, nickel chloride concentration 40g/L, boric acid concentration 40g/L, pH: 3.4. Electroplating time: 25 minutes, bath temperature: 58°C. The current density is: 1A/dm2.

Step 9, pearl nickel plating: move the workpiece to the pearl nickel plating bath, the pearl nickel plating bath composition: nickel sulfate concentration 400g/L, nickel chloride concentration 35g/L, boric acid concentration 51g/L, pH: 3.9 . Electroplating time: 15 minutes, bath temperature: 61°C. The current density is: 3A/dm2. Application of slotting additives: pearl nickel plating p1: 6 ml/L, p2: 15 ml/L, sand agent AF6: 0.25ml/L.

Step 10, nickel sealing: move the workpiece to the nickel sealing bath solution, the components of the nickel sealing bath solution: nickel sulfate concentration 230g/L, nickel chloride concentration 60g/L, boric acid concentration 30g/L, pH: 4.4. Electroplating time: 5 minutes, bath temperature: 61°C. The current density is: 2A/dm2.

Step 11, black chromium plating: the workpiece is moved to the black chromium plating bath, the black chromium plating bath composition: chromic anhydride concentration 427g/L, trivalent chromium concentration 3.7g/L, electroplating time: 5 minutes, tank Liquid temperature: 13°C. The current density is: 20A/dm2.

Step 12, hot water washing: move the workpiece to a hot water bath with a temperature of 65°C for 6 minutes.

Step 13, Lower hanging: Remove the workpieces from the hanger, place the turnover baskets one by one, and wait for the kind and dry treatment.

Step 14. Drying: Put the workpiece into the drying tunnel for drying, so that there is no water stain on the surface of the workpiece.

Step 15, packing: inspect and pack according to requirements.

Embodiment 2, tailpipe mist plating black chrome process, comprises the following steps:

Put the workpiece on the special hanger in advance, and wait for electroplating.

Step 1. Hot-dipping to remove wax; soak the workpiece in wax-removing water with a concentration of 150ml/L. The soaking time is 20 minutes, and the temperature of the wax-removing liquid is 90°C.

Step 2. Ultrasonic wax removal: soak the workpiece in wax removal water with a concentration of 30ml/L for 10 minutes, the temperature of the wax removal liquid is 90°C, and the ultrasonic hertz power is 30kHz.

Step 3, hot dip degreasing: soak the workpiece in a degreasing solution with a concentration of 90g/L, the soaking time is 10 minutes, and the temperature of the degreasing solution is 70°C.

Step 4, anode electrolysis: soak the workpiece in a degreasing solution with a concentration of 90g/L, the electrolysis time is 10 minutes, and the temperature of the degreasing solution is 70°C. The current density is: 10A/dm2.

Step 5, acid electrolysis: transfer the workpiece to a hydrochloric acid bath with a concentration of 400ml/L, the electrolysis time is 10 minutes, and the temperature is normal temperature without heating. The current density is: 3A/dm2.

Step 6, impact nickel plating: transfer the workpiece to the impact nickel plating bath, the impact nickel plating bath components: hydrochloric acid concentration 60ml/L, nickel chloride concentration 350g/L, electrolysis time: 10 minutes, without heating . The current density is: 3A/dm2.

Step 7, activation: transfer the workpiece to the sulfuric acid activation bath with a concentration of 60ml/L, soaking time: 20 seconds. No heating required.

Step 8, semi-bright nickel plating: the workpiece is moved to the semi-bright nickel bath, the semi-bright nickel bath components: nickel sulfate concentration 320g/L, nickel chloride concentration 50g/L, boric acid concentration 50g/L, pH: 3.6. Electroplating time: 35 minutes, bath temperature: 65°C. The current density is: 3A/dm2.

Step 9, pearl nickel plating: move the workpiece to the pearl nickel plating bath, the pearl nickel plating bath components: nickel sulfate concentration 440g/L, nickel chloride concentration 45g/L, boric acid concentration 55g/L, pH: 4.3 . Electroplating time: 25 minutes, bath temperature: 65°C. The current density is: 6A/dm2. Application of slotting additives: pearl nickel plating p1: 6 ml/L, p2: 15 ml/L, sand agent AF6: 0.25ml/L.

Step 10, nickel sealing: move the workpiece to the nickel sealing bath solution, the components of the nickel sealing bath solution: nickel sulfate concentration 250g/L, nickel chloride concentration 80g/L, boric acid concentration 35g/L, pH: 4.9. Electroplating time: 10 minutes, bath temperature: 65°C. The current density is: 5A/dm2.

Step 11, black chromium plating: the workpiece is moved to the black chromium plating bath, the black chromium plating bath composition: chromic anhydride concentration 472g/L, trivalent chromium concentration 15g/L, electroplating time: 10 minutes, bath solution Temperature: 24°C. The current density is: 40A/dm2.

Step 12. Hot water washing: move the workpiece to a hot water tank with a temperature of 80°C for 10 minutes.

Step 13, Lower hanging: Remove the workpieces from the hanger, place the turnover baskets one by one, and wait for the kind and dry treatment.

Step 14. Drying: Put the workpiece into the drying tunnel for drying, so that there is no water stain on the surface of the workpiece.

Step 15, packing: inspect and pack according to requirements.

Embodiment 3, tail pipe mist plating black chrome process, comprises the following steps:

Put the workpiece on the special hanger in advance, and wait for electroplating.

Step 1. Hot-dipping to remove wax; soak the workpiece in wax-removing water with a concentration of 100ml/L. The soaking time is 15 minutes, and the temperature of the wax-removing liquid is 70°C.

Step 2. Ultrasonic wax removal: soak the workpiece in wax removal water with a concentration of 20ml/L for 8 minutes, the temperature of the wax removal liquid is 70°C, and the ultrasonic hertz power is 25kHz.

Step 3, hot dip degreasing: soak the workpiece in a degreasing solution with a concentration of 65g/L, the soaking time is 8 minutes, and the temperature of the degreasing solution is 60°C.

Step 4, anode electrolysis: soak the workpiece in a degreasing solution with a concentration of 60g/L, the electrolysis time is 8 minutes, and the temperature of the degreasing solution is 60°C. The current density is: 8A/dm2.

Step 5. Acid electrolysis: transfer the workpiece to a hydrochloric acid bath with a concentration of 350ml/L, the electrolysis time is 8 minutes, and the temperature is normal temperature without heating. The current density is: 2.5A/dm2.

Step 6, impact nickel plating: transfer the workpiece to the impact nickel plating bath, the impact nickel plating bath components: hydrochloric acid concentration 50ml/L, nickel chloride concentration 300g/L, electrolysis time: 8 minutes, without heating . The current density is: 2.5A/dm2.

Step 7. Activation: Transfer the workpiece to a sulfuric acid activation bath with a concentration of 50ml/L, soaking time: 15 seconds. No heating required.

Step 8, semi-bright nickel plating: the workpiece is moved to the semi-bright nickel bath, the semi-bright nickel bath components: nickel sulfate concentration 300g/L, nickel chloride concentration 45g/L, boric acid concentration 45g/L, PH: 3.5. Electroplating time: 30 minutes, bath temperature: 62°C. The current density is: 2.5A/dm2.

Step 9, pearl nickel plating: move the workpiece to the pearl nickel plating bath, the pearl nickel plating bath components: nickel sulfate concentration 420g/L, nickel chloride concentration 40g/L, boric acid concentration 53g/L, pH: 4.1 . Electroplating time: 20 minutes, bath temperature: 63°C. The current density is: 4.5A/dm2. Application of slotting additives: pearl nickel plating p1: 6 ml/L, p2: 15 ml/L, sand agent AF6: 0.25 ml/L.

Step 10, nickel sealing: move the workpiece to the nickel sealing bath solution, the components of the nickel sealing bath solution: nickel sulfate concentration 240g/L, nickel chloride concentration 70g/L, boric acid concentration 32.5g/L, pH: 4.7. Electroplating time: 8 minutes, bath temperature: 63°C. The current density is: 3.5A/dm2.

Step 11, black chromium plating: the workpiece is moved to the black chromium plating bath, the black chromium plating bath composition: chromic anhydride concentration 450g/L, trivalent chromium concentration 10g/L, electroplating time: 8 minutes, bath solution Temperature: 20°C. The current density is: 30A/dm2.

Step 12, hot water washing: move the workpiece to a hot water tank with a temperature of 70°C for 8 minutes.

Step 13, Lower hanging: Remove the workpieces from the hanger, place the turnover baskets one by one, and wait for the kind and dry treatment.

Step 14. Drying: Put the workpiece into the drying tunnel for drying, so that there is no water stain on the surface of the workpiece.

Step 15, packing: inspect and pack according to requirements.

Comparative example: bright nickel plus black chrome plating process

Step 1. Degreasing by hot dipping: Soak the workpiece in a degreasing solution with a concentration of 65g/L. The soaking time is 8 minutes, and the temperature of the degreasing solution is 60°C.

Step 2, anode electrolysis: immerse the workpiece in a degreasing solution with a concentration of 60g/L, the electrolysis time is 8 minutes, and the temperature of the degreasing solution is 60°C. The current density is: 8A/dm2.

Step 3. Acid electrolysis: transfer the workpiece to a hydrochloric acid bath with a concentration of 350ml/L. The electrolysis time is 8 minutes, and the temperature is normal temperature without heating. The current density is: 2.5A/dm2.

Step 4, impact nickel plating: transfer the workpiece to the impact nickel plating bath, the impact nickel plating bath components: hydrochloric acid concentration 50ml/L, nickel chloride concentration 300g/L, electrolysis time: 8 minutes, without heating . The current density is: 2.5A/dm2.

Step 5, activation: transfer the workpiece to the sulfuric acid activation bath with a concentration of 50ml/L, soaking time: 15 seconds. No heating required.

Step 6, acid copper: transfer the workpiece to the acid copper bath, the acid copper bath components: copper sulfate concentration 200g/L, sulfuric acid concentration 33ml/L, chloride ion concentration 100mg/L, electroplating time: 36 minutes , Bath temperature: 24°C. The current density is: 2.5A/dm2.

Step 7, semi-bright nickel plating: the workpiece is moved to the semi-bright nickel bath, the semi-bright nickel bath components: nickel sulfate concentration 300g/L, nickel chloride concentration 45g/L, boric acid concentration 45g/L, PH: 3.5. Electroplating time: 30 minutes, bath temperature: 62°C. The current density is: 2.5A/dm2.

Step 8, bright nickel: move the workpiece to the bright nickel bath, bright nickel bath components: nickel sulfate concentration 280g/L, nickel chloride concentration 50g/L, boric acid concentration 45g/L, pH: 4.5. Electroplating time: 36 minutes, bath temperature: 55°C. The current density is: 2.5A/dm2.

Step 9, nickel sealing: move the workpiece to the nickel sealing bath solution, the components of the nickel sealing bath solution: nickel sulfate concentration 240g/L, nickel chloride concentration 70g/L, boric acid concentration 32.5g/L, pH: 4.7. Electroplating time: 8 minutes, bath temperature: 63°C. The current density is: 3.5A/dm2.

Step 10, black chromium plating: the workpiece is moved to the black chromium plating bath, the black chromium plating bath composition: chromic anhydride concentration 450g/L, trivalent chromium concentration 10g/L, electroplating time is: 8 minutes, bath solution Temperature: 20°C. The current density is: 30A/dm2.

Step 11, hot water washing: move the workpiece to a hot water tank with a temperature of 70°C for 8 minutes.

Step 12, Lower hanging: Remove the workpieces from the hanger, place the turnover baskets one by one, and wait for the kind and dry treatment.

Step 13, drying: put the workpiece into the drying tunnel for drying, so that the surface of the workpiece is free from water stains.

Step 14, packing: inspect and pack according to requirements.

Embodiment 1-3 electroplating process and comparative example electroplating process comparison table are as follows:

It can be seen from the above table that the black chromium electroplating process of the tailpipe in Examples 1-3 increases the pre-treatment wax removal process, optimizes the cleanliness of the parts, eliminates burr defects, and improves the bonding force. Cancel the acid copper process, increase the production capacity by 26.4%, and optimize the binding force test. The pearl nickel plating process replaces the bright nickel process, which improves the appearance requirements, and the color is uniform, which greatly improves the pass rate of the product, and the salt spray test is also improved.

As shown in Figure 2, the traditional stainless steel substrate electroplating process flow chart, this application optimizes the process flow, cancels the acid copper base coating, shortens the electroplating cycle time, and increases the production capacity by 26.4%. Acid copper primer requires 10μm plating layer, which requires 36 minutes of electroplating time. The entire electroplating process (excluding water washing time) takes 136 minutes in the traditional process. The optimized process of this application only takes 100 minutes. The process time is saved by 26.4%, and the production capacity is increased by 26.4%.

As shown in Figures 3 and 4, the present invention replaces the traditional bright nickel coating process with the pearl nickel coating process to improve the appearance defects on the blank, such as pits and pits. The color of the pearl nickel plating is uniform and white, and it is not easy to leave fingerprints and black spots. When the thickness of the pearl nickel plating reaches 10 microns, it can be plated with an appearance close to the effect of stainless steel, titanium or aluminum. And the pearl nickel plating layer is easy to chrome-plate, which increases the binding force of subsequent black chrome plating. In addition, the matte color of the pearl nickel plating layer has a slight luster and soft color, which can avoid visual fatigue of the eyes. The positioning performance of the pearl nickel plating solution is better than that of bright nickel.

The technical performance index of this application is as follows:

Appearance: Compared with the traditional bright black chrome plating, the black matte of this application has superior visual sense, uniform and clear color, more metallic feeling, and solves the appearance defects of bright black chrome plating products, such as pitting and burrs.

Performance test: High and low temperature bonding force test, after storing the parts at 600±10°C for 1h±15 minutes, then immersing them in water at 23±3°C, the coating has no bubbles and no flakes. Compared with the sulfate-type trivalent plating The electroplating process of black chromium improves the wear resistance, and the hexavalent black chromium plating can be polished after electroplating. However, the high and low temperature bonding strength test of traditional bright black chrome plating only meets the storage conditions of 300±10°C.

Performance test, salt spray acid test (CASS) can reach 72H hours, the general requirement is 66H, an increase of 9%.

Claims (7)

1. The black chromium plating process for the tailpipe is characterized in that it includes the following steps: Step 1, hot dip wax removal; Step 2. Ultrasonic wax removal; Step 3, hot dip degreasing; Step 4, anode electrolysis; Step 5, acid electrolysis; Step 6, impact nickel plating; Step 7, activation; Step 8, semi-bright nickel plating; Step 9: Pearl nickel plating; The bath composition of described pearl nickel plating is as follows: nickel sulfate concentration 400-440g/L, nickel chloride concentration 35-45g/L, boric acid concentration 51-55g/L, pH:3.9-4.3; Electroplating time is 15- For 25 minutes, the bath temperature is 61-65°C; the current density is 3-6A/dm2; Step 10: Nickel seal; Step 11: black chrome plating; The bath composition of described black chromium plating is as follows: chromic anhydride concentration 427-472g/L, trivalent chromium concentration 3.7-15g/L; Electroplating time is 5-10 minutes, bath temperature is 13-24 ℃; 20-40A/dm2; Step 12, hot water washing; Step 13, hanging down; Step 14, drying; Step 15, packing. 2. according to the described tailpipe fog plating black chrome process of claim 1, it is characterized in that: in described step 2, ultrasonic dewaxing is that workpiece is immersed in the dewaxing water of concentration 10-30ml/L, and immersion time is 5 -10 minutes, the temperature of the wax removal solution is 60-90°C, and the ultrasonic hertz power is 20kHz-30kHz. 3. according to the described tailpipe mist plating black chromium process of claim 1, it is characterized in that: in described step 4, anode electrolysis is to immerse workpiece in the degreasing liquid of concentration 30-90g/L, electrolysis time is 6 -10 minutes, the temperature of the degreasing liquid is 50-70°C; the current density is 4-10A/dm2. 4. according to the tailpipe fog plating black chromium process described in claim 1, it is characterized in that: in described step 6, the bath composition of impact nickel plating is as follows: hydrochloric acid concentration 40-60ml/L, nickel chloride concentration 280 -350g/L, the electrolysis time is 6-10 minutes, and the current density is 1-3A/dm2. 5. according to the tailpipe fog plating black chromium process described in claim 1, it is characterized in that: in described step 8, the bath composition of semi-bright nickel plating is as follows: nickel sulfate concentration 280-320g/L, nickel chloride Concentration 40-50g/L, boric acid concentration 40-50g/L, pH: 3.4-3.6; electroplating time: 25-35 minutes, bath temperature: 58-65°C; current density: 1-3A/dm2. 6. According to the black chromium plating process for tailpipe according to claim 1, it is characterized in that: in said step 10, the bath composition of nickel seal is as follows: nickel sulfate concentration 230-250g/L, nickel chloride concentration 60 -80g/L, boric acid concentration 30-35g/L, pH: 4.4-4.9; electroplating time is 5-10 minutes, bath temperature is 61-65°C; current density is 2-5A/dm2. 7. The black chromium plating process for tailpipe according to claim 1, characterized in that: in step 12, when washing with hot water, the workpiece is moved to a hot water tank with a temperature of 65-80°C, and the time for washing with hot water is: 6-10 minutes.

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