Preparation method of decorative coating on surface of copper alloy

Abstract

The invention discloses a preparation method of a decorative coating on the surface of a copper alloy. The preparation method comprises the following steps: step 1, grinding and polishing the surface of the copper alloy and cleaning; 2, the copper alloy obtained in the step 1 is subjected to heating and heat preservation treatment; thirdly, the surface of the copper alloy obtained in the second step is cleaned through a plasma machine; 4, depositing a chromium layer on the surface of the copper alloy obtained in the step 3; step 5, depositing a TiCN colored decorative film layer on the surface of the chromium layer of the copper alloy obtained in the step 4 by using a medium-frequency magnetron sputtering method; wherein during deposition in the step 5, a target material is a titanium target material, and reaction gases are N2 and C2H2; the prepared decorative coating is high in film-substrate binding force, environmentally friendly and free of pollution, and has good service performance in severe environments such as abrasion and corrosion.

Description

Technical Field

[0001] The invention belongs to the field of copper alloy surface treatment, and in particular relates to a method for preparing a decorative coating on the surface of a copper alloy. Background Art

[0002] Copper alloy is one of the earliest ancient metals discovered by humans. It was discovered and used by people more than 3,000 years ago. Copper alloy has excellent electrical and thermal conductivity, good anti-magnetic and processing properties, high elastic limit and fatigue limit, etc., and is widely used in the fields of electronics, aerospace, transportation industry and architectural decoration. With the improvement of the quality of life, copper alloys with a single color can no longer meet people's demand for decorative properties. In addition, copper alloys also have defects such as poor wear resistance, low hardness, and easy corrosion in harsh service environments, which further limits the application of copper and copper alloys.

[0003] At present, electroplating, chemical plating, and painting are commonly used to improve the decorative properties of copper alloy surfaces. Although the coating is dense and uniform with high gloss, it has poor bonding with the copper alloy substrate and is prone to peeling after long-term use. At the same time, there are toxic substances in the electroplating solution, which poses great environmental hazards. Chemical plating is also polluting and the coating color is single. The coating process is complex and polluting, and the hardness of the surface film is low. Although the vacuum method is used to prepare decorative coatings, it is green and environmentally friendly, but due to the easy formation of oxide film on the copper surface, the film-base bonding is poor, and the copper substrate itself has a certain color, which has a certain impact on the color of the film.

[0004] At present, in order to increase the film-base bonding strength and color stability of decorative coatings, the Ni or Cr base layer is first prepared by electroplating, and then vacuum ion plating is performed after polishing. However, this method still has the problem of environmental pollution, and the process is cumbersome and the production cost is high. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing a decorative coating on the surface of a copper alloy, so as to solve the problems in the prior art of first using an electroplating process to prepare a Ni or Cr base layer, then polishing it and then vacuum ion plating a decorative film layer, which leads to environmental pollution, complicated procedures and high production costs.

[0006] The present invention adopts the following technical scheme: a method for preparing a decorative coating on the surface of a copper alloy, comprising:

[0007] Step 1: Grind, polish and clean the copper alloy surface;

[0008] Step 2: heating and heat-insulating the copper alloy obtained in step 1;

[0009] Step 3: Cleaning the surface of the copper alloy obtained in step 2 using a plasma machine;

[0010] Step 4: depositing a chromium layer on the surface of the copper alloy obtained in step 3;

[0011] Step 5: depositing a TiCN colored decorative film layer on the surface of the chromium layer of the copper alloy obtained in step 4 by using a medium frequency magnetron sputtering method;

[0012] Among them, during the deposition in step 5, the target material is a titanium target material, and the reaction gases are N2 and C2H2.

[0013] Furthermore, the heat preservation treatment conditions in step 2 are: 150-200° C., heat preservation for 20-40 minutes.

[0014] Furthermore, the cleaning conditions of step 3 are: vacuum degree of 1.0-1.5 Pa, gas atmosphere of argon, and cleaning time of 5-10 min.

[0015] Furthermore, the deposition conditions of step 4 are: deposition time is 10 to 20 minutes, and vacuum degree is 0.02 to 0.1 Pa.

[0016] Furthermore, in step 5, the flow ratio of N2 and C2H2 is 0.6 to 4:1.

[0017] Furthermore, the deposition conditions in step 5 are: temperature of 150°C to 200°C, vacuum of 0.4 to 0.5 Pa, and deposition time of 30 to 60 min.

[0018] The beneficial effects of the present invention are:

[0019] The present invention firstly grinds and polishes the copper substrate to remove the oxide film layer on the surface, then performs ultrasonic rinsing to remove the oil stain on the surface, puts it into a vacuum coating machine, evacuates it, performs plasma cleaning and etching, then uses vacuum multi-arc ion plating to prepare a chromium bottom layer, and then uses medium-frequency magnetron sputtering to prepare a decorative coating. The prepared decorative coating has strong film-base bonding, is green and environmentally friendly, has no pollution, and has good service performance in harsh environments such as wear and corrosion.

[0020] The present invention avoids the problem of large environmental pollution caused by traditional decorative coating processes on the surface of copper and copper alloys and the problem of poor bonding strength of a single vacuum coating process; the present invention first uses multi-arc ion plating to prepare a Cr primer layer on the surface of a copper alloy substrate to improve the bonding strength between the film layer and the substrate; the Cr primer layer has strong bonding strength and can effectively cover the color of the copper substrate; then a colored TiCN film layer is prepared on the surface; the TiCN film layer is composed of TiC, TiN and C atoms; TiC and TiN improve the hardness and corrosion resistance of the coating, and the C atoms improve the friction and lubrication properties of the coating;

[0021] The surface of the film layer prepared by medium-frequency magnetron sputtering coating in the present invention is flat, smooth and dense, so the film layer has bright and stable color, strong bonding performance with the substrate, excellent wear resistance and corrosion resistance, which can greatly broaden the application scenarios of copper and its alloys. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1-9 The following are photos of samples obtained in Examples 1-9 of the present invention. DETAILED DESCRIPTION

[0023] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] The invention discloses a method for preparing a decorative coating on the surface of a copper alloy, comprising:

[0025] Step 1: Grind, polish and clean the copper alloy surface

[0026] The sample surface was polished with 800#, 1000#, 1200#, 2000# sandpaper and abrasive paste, then rinsed with deionized water, ultrasonically cleaned with anhydrous ethanol for 15 to 20 minutes, and then quickly dried.

[0027] Step 2: Heat and keep the copper alloy obtained in step 1

[0028] Place the sample after step 1 in a vacuum coating machine, adjust the target-substrate distance to 100-150 mm, start vacuuming, and when the vacuum degree in the chamber reaches 0.03-0.05 Pa, slowly heat the temperature to 150-200°C and keep it warm for 20-40 minutes. Heating and heat preservation treatment can improve the density of the film layer by increasing the substrate temperature, and on the other hand, it can help maintain the high cleanliness of the vacuum chamber and reduce pollution.

[0029] Step 3: Use a plasma machine to clean the surface of the copper alloy obtained in step 2

[0030] Plasma cleaning and etching: Continue to evacuate until the vacuum degree in the chamber reaches 3.0~5.0×10 -3 After the sample reaches 1.0-1.5 Pa, argon gas with a purity of ≥99.99% is introduced into the vacuum chamber to raise the vacuum degree in the chamber to 1.0-1.5 Pa. The rotation speed of the turret is set to 15-30 r / min, and the revolution speed is 2-4 r / min. Then, the plasma etching system is turned on, and the ion source voltage is set to 700-1000 V, and the duty cycle is 50%-70%. After plasma cleaning and etching the sample surface for 5-10 minutes, the sample surface is further cleaned to enhance the membrane-base bonding strength.

[0031] Step 4: Deposit a chromium layer on the surface of the copper alloy obtained in step 3

[0032] Continue to evacuate the chamber on the basis of step 3. When the vacuum degree in the chamber reaches 0.02-0.1 Pa, open the shielding baffle of the Cr arc target, turn on the bias power supply and the multi-arc ion plating arc power supply in turn, set the pulse bias to 200-300 V, the duty cycle to 50-70%, the current to 60-80 A, and deposit for 10-20 minutes.

[0033] Step 5: Deposit a TiCN colored decorative film layer on the surface of the chromium layer of the copper alloy obtained in step 4 by using a medium frequency magnetron sputtering method. During the deposition in step 5, the target material is a titanium target material, the reaction gases are N2 and C2H2, and the flow ratio of N2 to C2H2 is 0.6 to 4:1.

[0034] On the basis of step 4, wait for the temperature in the vacuum chamber to drop to 150℃~200℃, introduce 20sccm~80sccm of N2 into the vacuum chamber, and then introduce 20~100sccm of C2H2 to raise the vacuum degree in the vacuum chamber to 0.4~0.5Pa. Turn on the sputtering Ti target shielding gear, turn on the bias power supply and the medium frequency magnetron sputtering power supply in turn, with a pulse bias of 100~150V, a duty cycle of 60~80%, a current of 60~80A, and deposit for 30~60min. When the temperature in the vacuum chamber drops below 50℃, fill the vacuum chamber with gas, cool it to room temperature, open the furnace and take out the sample.

[0035] Example 1

[0036] A copper alloy sample with a size of 50 mm × 50 mm × 2 mm was taken, and the surface was polished with 800#, 1000#, 1200#, and 1500# sandpaper in sequence, and then polished with abrasive paste. It was then rinsed with deionized water, ultrasonically cleaned with anhydrous ethanol for 20 minutes, and then quickly dried.

[0037] The processed samples were placed in the SP-1912ASI vacuum coating equipment of Beijing Shiliyuan Company, the target-substrate distance was adjusted to 110 mm, the vacuum chamber door was closed, and the vacuum operation was started. When the vacuum degree in the chamber reached 0.05 Pa, the heating tube was used to slowly heat the room temperature to 150°C and keep it warm for 30 minutes.

[0038] Plasma cleaning and etching: Continue to evacuate until the vacuum degree in the chamber reaches 4.0×10 -3 After the sample reaches 0.04 Pa, argon gas with a purity of ≥99.99% is introduced into the vacuum chamber at a flow rate of 1000 sccm to make the vacuum degree in the chamber reach 1.0 Pa. The rotation speed of the turret is set to 20 r / min and the revolution speed is set to 2 r / min, then the plasma etching system is turned on, the ion source voltage is set to 800 V, the duty cycle is set to 60%, and the sample surface is plasma cleaned and etched for 6 minutes before the plasma etching system is turned off.

[0039] Continue to evacuate the chamber. When the vacuum degree in the chamber reaches 0.05 Pa, open the shielding baffle of the Cr arc target, turn on the bias power supply and arc power supply in turn, set the pulse bias to 250 V, the duty cycle to 50%, the current to 70 A, and deposit for 15 minutes.

[0040] When the temperature in the vacuum chamber drops to 150°C, introduce 60sccm of N2 and 20sccm of C2H2 into the vacuum chamber to raise the vacuum degree in the vacuum chamber to 0.5Pa. Turn on the sputtering Ti target shielding lever, turn on the bias power supply and the medium frequency magnetron sputtering power supply in turn, adjust the pulse bias to 150V, the duty cycle to 60%, the current to 70A, and deposit for 60 minutes. When the temperature in the vacuum chamber drops below 50°C, inflate the vacuum chamber, cool it to room temperature, open the furnace and take out the sample. The surface color of the sample prepared in Example 1 is as follows: Figure 1 shown.

[0041] The steps of Example 2-9 are the same as those of Example 1, except for the flow rates of N2 and C2H2. The specific data are shown in Table 1.

[0042] Table 1 Flow rates of N2 and C2H2 in each example and Lab values ​​of the obtained samples

[0043]

[0044] The samples obtained in Examples 1-9 were tested according to the national standard GB / T 10125-2021 to test the corrosion resistance of the film layer. A neutral salt spray test was carried out in a 5% NaCl solution at a corrosion temperature of 35°C. When the sample was placed, the test surface was 30° from the vertical surface so that the salt spray could settle freely on the sample surface. The corrosion time was 72h. After the test, the sample was naturally dried indoors for 1h and then rinsed with running water. After drying, the sample was evaluated for corrosion resistance according to GB / T6461-2002, which was divided into 1 to 9 grades, with 9 being the best. The test results are shown in Table 1.

[0045] The bonding strength between the film layer and the substrate is tested according to the national standard GB / T 9286-2021. The test tool is a cross-cut tester, which is a multi-blade cutter with 6 cutting surfaces and a cutter gap of 1mm. During the test, the cross-cut tester is used to pull 3 to 4 cm parallel to the surface of the film layer, and then pull it another 3 to 4 cm in the vertical direction to form a small square. After cleaning the surface, apply 3M tape, ensure that the tape is completely attached to the test area, and then quickly pull the tape apart. Then use visual inspection or a magnifying glass to compare the test results in the standard for grading, which is divided into 0 to 5 levels, with 0 being the best, and generally 0 to 2 being considered qualified. The test results are shown in Table 2.

[0046] Table 2

[0047] project Corrosion resistance grade Film bonding strength level Example 1 Level 8 Level 0 Example 2 Level 8 Level 0 Example 3 Level 9 Level 0 Example 4 Level 8 Level 0 Example 5 Level 9 Level 0 Example 6 Level 8 Level 0 Example 7 Level 8 Level 0 Example 8 Level 9 Level 0 Example 9 Level 8 Level 0

[0048] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a decorative coating on a copper alloy surface, characterized in that: include: Step 1: Grind, polish and clean the copper alloy surface; Step 2: heating and heat-insulating the copper alloy obtained in step 1; Step 3: Cleaning the surface of the copper alloy obtained in step 2 using a plasma machine; Step 4: depositing a chromium layer on the surface of the copper alloy obtained in step 3; Step 5: depositing a TiCN colored decorative film layer on the surface of the chromium layer of the copper alloy obtained in step 4 by using a medium frequency magnetron sputtering method; Among them, during the deposition in step 5, the target material is a titanium target material, and the reaction gases are N2 and C2H2.

2. The method for preparing a decorative coating on a copper alloy surface according to claim 1, characterized in that: The heat preservation conditions in step 2 are: 150-200° C., and 20-40 min.

3. The method for preparing a decorative coating on a copper alloy surface according to claim 1, characterized in that: The cleaning conditions of step 3 are: vacuum degree of 1.0-1.5 Pa, gas atmosphere of argon, and cleaning time of 5-10 min.

4. The method for preparing a decorative coating on a copper alloy surface according to claim 1, characterized in that: The deposition conditions of step 4 are: deposition time of 10 to 20 minutes and vacuum degree of 0.02 to 0.1 Pa.

5. The method for preparing a decorative coating on a copper alloy surface according to claim 1, characterized in that: In step 5, the flow ratio of N2 and C2H2 is 0.6 to 4:

1.

6. The method for preparing a decorative coating on a copper alloy surface according to claim 1, characterized in that: The deposition conditions in step 5 are: temperature of 150° C. to 200° C., vacuum degree of 0.4 to 0.5 Pa, and deposition time of 30 to 60 min.

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