A wear-resistant CrZrN solid solution ceramic coating on a surface of a TC4 alloy and a preparation method thereof

Abstract

The application discloses a kind of TC4 alloy surface wear-resistant CrZrN solid solution ceramic coating and preparation method thereof, belong to TC4 alloy surface treatment field, the coating is prepared CrZrN ceramic coating using double-glow plasma surface metallurgy technology for TC4 alloy surface, the coating includes deposition layer and diffusion layer, Cr, Zr, N, Ti content in diffusion layer gradient change, alleviate the failure of coating caused by composition mutation and property difference;Compared with CrN binary coating, the CrZrN ceramic coating prepared by the application has the advantages of realizing solid solution strengthening, refining the grain and realizing metallurgical bonding between the coating and the substrate, which can effectively improve the service life of TC4 alloy substrate and can be applied to wear-resistant parts protection in the fields of aviation industry and shipbuilding industry.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of TC4 alloy surface treatment, and particularly relates to a TC4 alloy surface wear-resistant CrZrN solid solution ceramic coating and a preparation method thereof. BACKGROUND

[0002] Most of the marine equipment is made of metal materials, and the moving parts bearing load are prone to wear failure in complex marine environment. TC4 alloy is widely used in marine engineering due to its small density, high specific strength, good corrosion resistance and other advantages, and is known as "marine metal". However, the surface hardness of TC4 is low, the friction coefficient is high, and the adhesive wear is prone to occur in the process of pair grinding, which seriously restricts the use range and service life. Among various countermeasures, coating technology is the most direct, effective and economic and feasible way to improve the surface hardness and wear resistance of the alloy, and has been widely used in the surface modification of titanium alloy. Transition metal nitride has high strength, high hardness and good wear resistance, and is a commonly used wear-resistant coating material. CrN coating with excellent corrosion resistance is considered as a potential protective material for long-term use of mechanical components of ships, but the CrN coating has pinholes, pores and columnar structures during deposition, which can accelerate solution erosion and reduce the performance of the coating. SUMMARY

[0003] The application provides a TC4 alloy surface wear-resistant CrZrN solid solution ceramic coating and a preparation method thereof, which solves the problem of poor wear resistance of TC4 alloy during service, that is, a CrZrN plating layer is prepared on the surface of the TC4 alloy, which greatly improves the wear resistance of the substrate and also realizes metallurgical bonding, thereby avoiding the coating failure problem caused by coating peeling, so that the service life of the TC4 alloy substrate is prolonged.

[0004] To achieve the above object, the application adopts the following technical scheme:

[0005] A TC4 alloy surface wear-resistant CrZrN solid solution ceramic coating is obtained by using double-glow plasma surface metallurgy technology to obtain a CrZrN gradient coating deposited on the surface of the substrate TC4 alloy, the CrZrN coating includes a diffusion layer close to the substrate side and a CrZrN deposition layer on the outermost layer; the thickness of the diffusion layer is about 1 mu m, and the thickness of the deposition layer is 6 mu m; CrN, ZrN, Zr7Cr3N 10 , Zr3Cr7N 10 solid solution are formed in the deposition layer; the elements of Cr, Zr and N diffuse from the coating to the inside of the substrate, and the Ti element diffuses from the substrate to the coating.

[0006] The preparation method of the above-mentioned TC4 alloy surface wear-resistant CrZrN solid solution ceramic coating comprises the following steps:

[0007] Step 1, substrate and target material pretreatment

[0008] Prepare the substrate TC4 alloy, polish it with 180#, 360#, 600# and 800# coarse sandpaper and 1#, 3# and 5# metallographic sandpaper in sequence, and then mechanically polish it with a polishing cloth and diamond polishing paste until it is smooth and mirror-like. After polishing the target material with 800# and 1500# sandpaper to remove the surface oxide film, it is placed in anhydrous ethanol for ultrasonic cleaning and then dried for standby use;

[0009] Step 2, vacuum chamber cleaning and workpiece placement

[0010] Polish the inner wall of the vacuum chamber and the protection cover of the worktable with 800# and 1500# sandpaper to remove the surface oxide film and impurities. Then, use a dust-free cloth dipped in anhydrous ethanol to clean the target material and the pretreated TC4 alloy. The Cr and Zr grid targets are used as the source electrode, and the TC4 alloy is used as the workpiece electrode.

[0011] Step 3, vacuum pumping

[0012] Turn on the mechanical pump to pump out the gas in the vacuum chamber. When the gas pressure reaches 0.1 Pa, continuously introduce argon gas. Perform gas cleaning three to four times in the range of 20-100 Pa to ensure that other gases in the furnace are discharged and to avoid the influence of gas impurities on the coating preparation process. After gas cleaning, adjust the gas pressure to 20 Pa and continuously introduce argon gas during coating preparation.

[0013] Step 4, glow starting

[0014] Start the bias power supply cabinet for 15 minutes until the glow is stable. Slowly adjust the workpiece voltage to 300 V. Perform Ar ion bombardment on the workpiece and target material for 30 minutes and 10 minutes, respectively, to achieve cleaning and preheating effects.

[0015] Step 5, preparation of CrZrN solid solution ceramic coating by double-glow plasma surface metallurgy technology

[0016] Use grid targets, high-purity chromium targets with a purity of 99.95%, and zirconium targets. Adjust the distance between the TC4 alloy substrate and the target material to 15-16 mm, the pressure in the furnace cavity to 30-35 Pa, the source voltage to 800-1000 V, and the workpiece voltage to 400-500 V. Sputter for 3 hours, introduce N2, and then sputter for another 4 hours to obtain a CrZrN solid solution ceramic coating.

[0017] Step 6, turn off the equipment

[0018] After the heat preservation is completed, slowly reduce the source voltage and workpiece voltage to 300 V, turn off N2, continuously introduce Ar2 for half an hour, and then directly adjust the two voltages to 0 and turn off the power supply.

[0019] As an improvement, the source voltage and the workpiece voltage described in step 6 are reduced to 300V at a rate of 50V and 20V per 5 minutes, respectively.

[0020] Application of the wear-resistant CrZrN solid solution ceramic coating on the surface of the TC4 alloy on ship or aviation materials.

[0021] Beneficial effects: The present application provides a wear-resistant CrZrN solid solution ceramic coating on the surface of the TC4 alloy and a preparation method thereof. The prepared CrZrN solid solution ceramic coating is combined with the TC4 alloy by plating and diffusion through the use of double-glow plasma surface metallurgy technology, so that the content of Cr, Zr, N and Ti in the diffusion layer changes in a gradient manner, the coating failure caused by component mutation and property difference is alleviated, the combination performance is good, the coating failure problem caused by coating peeling is avoided, the service life of the TC4 alloy substrate can be effectively improved, the addition of Zr element can refine the grain, replace Cr atoms to form a (Cr, X) N solid solution, realize solid solution strengthening, and further improve the performance of the coating, which can greatly improve the wear resistance of the substrate, effectively protect the substrate material in a friction environment, and can be applied to wear-resistant parts protection in the fields of aviation industry and shipbuilding industry. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 A schematic view of the surface micro-morphology of the coating prepared for Example 1 is shown in the figure.

[0023] Figure 2 A schematic view of the surface micro-morphology of the coating prepared for Comparative Example 1 is shown in the figure.

[0024] Figure 3 A cross-sectional view of the coating prepared for Example 1 is shown in the figure.

[0025] Figure 4 A schematic view of the surface XRD of the coating prepared for Example 1 is shown in the figure.

[0026] Figure 5 A schematic view of the friction coefficient curve of Example 1, Comparative Example 1 and the TC4 substrate is shown in the figure.

[0027] Figure 6 A schematic view of the three-dimensional wear scar morphology of Example 1 and Comparative Example 1 under a load of 2.2N is shown in the figure, wherein (a) is Example 1; (b) is Comparative Example 1.

[0028] Figure 7 A schematic view of the wear profile of Example 1 and Comparative Example 1 is shown in the figure. DETAILED DESCRIPTION

[0029] The present application will be described in detail below in combination with the drawings and specific embodiments:

[0030] As Figures 1-5As shown, the present application provides a TC4 alloy surface wear-resistant CrZrN solid solution ceramic coating, the coating is prepared by using the grid target process of double glow plasma surface metallurgy technology, and the target material is specifically a chromium target and a zirconium target, and the purity of the target material is 99.95%.

[0031] The application will be further described in detail through specific embodiments.

[0032] Embodiment 1

[0033] A TC4 alloy surface wear-resistant CrZrN solid solution ceramic coating is obtained by using double-layer glow plasma metallurgy technology to deposit a CrZrN solid solution ceramic coating on the surface of a TC4 alloy, as shown in Figure 1 As shown, the coating is smooth, flat and dense, and no obvious defects such as voids and pits are present, as shown in Figure 3 As shown, the CrZrN solid solution ceramic coating includes a Cr diffusion layer, a Zr diffusion layer, an N diffusion layer, a Ti diffusion layer and a CrZrN deposition layer from the surface of the substrate outward, the content of Cr, Zr and N in the diffusion layer gradually decreases from the surface of the diffusion layer to the inside of the TC4 alloy, and the content of Ti gradually decreases from the inside of the TC4 alloy to the surface of the diffusion layer, as shown in Figure 4 As shown, the deposition layer forms CrN, ZrN, Zr7Cr3N 10 and Zr3Cr7N 10 solid solutions.

[0034] The preparation method of the above coating includes the following steps:

[0035] Step 1, substrate material pretreatment

[0036] Prepare a TC4 alloy sample with a size of 15x15x4 mm, polish it step by step using 180#, 360#, 600# and 800# coarse sandpaper and 1#, 3# and 5# metallographic sandpaper, mechanically polish it to a smooth mirror surface, clean it with ultrasonic cleaning in anhydrous ethanol and then dry it for standby use;

[0037] Step 2, vacuum chamber cleaning and workpiece placement

[0038] Polish the target material, the inner wall of the vacuum chamber and the protection cover of the worktable using 800# and 1500# sandpaper in sequence to remove the surface oxide film and impurities, then wipe them with a dust-free cloth dipped in anhydrous ethanol until there are no obvious stains, and then place the target material and the pretreated TC4 alloy after cleaning, use the Cr and Zr grid target as the source electrode, and use the TC4 alloy as the workpiece electrode;

[0039] Step 3, vacuum pumping

[0040] Open the mechanical pump, extract the vacuum chamber gas, when the air pressure reaches 0.1 Pa, continue to introduce argon, carry out gas cleaning three to four times in the range of 20-100 Pa, ensure that other gases in the furnace are discharged, and try to avoid the influence of gas impurities on the coating preparation process, and adjust the gas pressure to 20 Pa after the gas cleaning is completed, and keep the argon continuously introduced during the coating preparation process;

[0041] Step 4, starting glow

[0042] Start the bias power supply cabinet for 15 minutes after the glow is stable, slowly adjust the workpiece voltage to 300V, and perform Ar ion bombardment on the workpiece and the target material for 30 minutes and 10 minutes respectively, which plays a cleaning and preheating role;

[0043] Step 5, preparation of CrZrN solid solution ceramic coating by double glow plasma surface metallurgy technology

[0044] The grid target is used, the target material is a high-purity chromium target with a purity of 99.95%, and a zirconium target; the distance between the TC4 alloy substrate and the target material is adjusted to 15-16mm, the pressure in the furnace cavity is 30-35 Pa, the source voltage is 800-1000V, the workpiece voltage is 400-500V, and the CrZrN solid solution ceramic coating is prepared after sputtering for 3h and then introducing N2 and sputtering for 4h;

[0045] Step 6, turn off the equipment

[0046] After the holding is finished, the source voltage and the workpiece voltage are respectively reduced to 300V at a speed of 50V and 20V per 5 minutes, N2 is turned off, Ar2 is continuously introduced, and the two voltages are directly adjusted to 0 after holding for half an hour.

[0047] Comparative Example 1

[0048] The coating preparation steps shown in Comparative Example 1 and Example 1 are different in that:

[0049] Step 5, preparation of CrN solid solution ceramic coating by double glow plasma surface metallurgy technology

[0050] The target material is a high-purity chromium target with a purity of 99.95%, the distance between the TC4 alloy substrate and the target material is adjusted to 12-16mm, the pressure in the furnace cavity is 20-35 Pa, the source voltage is 800-1000V, the workpiece voltage is 400-500V, the CrN binary ceramic coating is prepared after sputtering for 3h and then introducing N2 and sputtering for 4h, and the coating surface appears obvious island growth, the surface roughness is high, and the coating is not uniform and smooth.

[0051] The coating prepared by example 1 and comparative example 1 is subjected to friction and wear test, the morphology after wear is observed, the rotating friction and wear tester is used to study the wear behavior of the coating in real environment, and the specific operation is as follows: the sample is placed on the loading platform, and is fixed by the clamp, the friction pair is selected as the Si3N4 ball with a diameter of 5 mm, the temperature is 25 DEG C, the rotating speed is 560 r / min, the load is 2.2 N, the friction radius is 2 mm, and the wear time is 15 min.

[0052] The experimental results show that:

[0053] As shown in Figures 5-7 Compared with the comparative example, the friction coefficient of example 1 is reduced, the wear profile is greatly reduced, and the wear volume is greatly reduced, indicating that the wear resistance of the example is improved.

[0054] In summary, the CrZrN solid solution ceramic coating prepared by the method of the present application can form metallurgical bonding between the coating and TC4 alloy by using double glow plasma surface metallurgy technology, the composition realizes continuous gradient change from the surface of the coating to the inside, the bonding performance is good, and the substrate material can be effectively protected in the friction environment.

[0055] The above is only the preferred embodiment of the present application, and those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can still be modified, or some or all of the technical features can be replaced by equivalents, and these modifications or replacements do not make the essence of the corresponding technical solution deviate from the scope of the technical solutions of the embodiments of the present application, and they should be covered in the protection scope of the present application.

Claims

1. A method for preparing a wear-resistant CrZrN solid solution ceramic coating on a surface of a TC4 alloy, characterized in that, It comprises the following steps: Step 1: after the TC4 alloy substrate and the target are placed in the reaction chamber, the Cr and Zr grid target is used as a source electrode, and the TC4 alloy is used as a workpiece electrode; Step 2: after the reaction chamber is cleaned of gas impurities, the workpiece and the target are subjected to Ar ion bombardment for 30 minutes and 10 minutes respectively, which plays a cleaning and preheating role; Step 3: the distance between the TC4 alloy substrate and the target is adjusted to 15-16 mm, the pressure in the furnace cavity is 30-35 Pa, the source voltage is 800-1000 V, the workpiece voltage is 400-500 V, N2 is introduced after sputtering for 3 hours, and the CrZrN solid solution ceramic coating is prepared after sputtering for 4 hours; Step 4: After the end, the source voltage and the workpiece voltage are reduced to 300V at a rate of 50V and 20V per 5 minutes respectively, N2 is turned off, Ar2 is continuously input for half an hour, then the two voltages are directly adjusted to 0, and the power is turned off; the coating is a CrZrN gradient coating deposited on the surface of the substrate TC4 alloy, the CrZrN gradient coating includes a diffusion layer close to the substrate side and a CrZrN deposition layer at the outermost layer; the contents of Cr, Zr, N and Ti in the diffusion layer change in a gradient, wherein the elements of Cr, Zr and N diffuse from the coating to the inside of the substrate, and the element of Ti diffuses from the substrate to the coating; the deposition layer forms CrN, ZrN, Zr7Cr3N 10 , Zr3Cr7N 10 solid solution.

2. The method of claim 1, wherein the method is characterized by: The treatment process of the substrate in step 1 is: the substrate TC4 alloy is prepared, and is polished by 180#, 360#, 600# and 800# coarse sandpaper and 1#, 3# and 5# metallographic sandpaper in turn, and then is mechanically polished to a smooth mirror surface by flannel and diamond polishing paste; the treatment process of the target is: after the surface oxide film is polished off by 800# and 1500# sandpaper, the target is placed in anhydrous ethanol for ultrasonic cleaning and then is dried for standby; the treatment process of the reaction chamber is: the inner wall of the vacuum chamber and the protection cover of the worktable are polished by 800# and 1500# sandpaper to remove the surface oxide film and impurities, and then are wiped with a dust-free cloth dipped in anhydrous ethanol until no obvious stains are left.

3. The method of claim 1 or 2, wherein the method is characterized by, The target is a high-purity chromium target and a zirconium target with a purity of 99.95%.

4. The method of claim 1, wherein the method of preparing a wear resistant CrZrN solid solution ceramic coating on a TC4 alloy surface is characterized by, The gas cleaning process in step 2 is: the mechanical pump is opened to extract the gas in the vacuum chamber, argon gas is continuously introduced when the gas pressure reaches 0.1 Pa, and the gas cleaning is carried out three to four times in the range of 20-100 Pa to ensure that other gases in the furnace are discharged and the influence of gas impurities on the coating preparation process is avoided as much as possible; after the gas cleaning is completed, the gas pressure is adjusted to 20 Pa, and the argon gas is continuously introduced during the coating preparation process.

5. The method of claim 1 or 4, wherein the method is characterized by, The cleaning and preheating process of the workpiece and the target in step 2 is: the bias power supply cabinet is started for 15 minutes until the glow is stable, the workpiece voltage is slowly adjusted to 300 V, and the workpiece and the target are subjected to Ar ion bombardment for 30 minutes and 10 minutes respectively.

6. The wear resistant CrZrN solid solution ceramic coating on the surface of TC4 alloy prepared by the method of any one of claims 1-5, characterized in that, The coating is a CrZrN gradient coating deposited on the surface of a substrate TC4 alloy, the CrZrN gradient coating comprises a diffusion layer close to the substrate side and a CrZrN deposition layer at the outermost layer; the content of Cr, Zr, N and Ti in the diffusion layer changes in a gradient manner, wherein the elements of Cr, Zr and N diffuse from the coating to the inside of the substrate, and the element of Ti diffuses from the substrate to the coating; the deposition layer forms CrN, ZrN, Zr7Cr3N 10 , Zr3Cr7N 10 solid solution.

7. The TC4 alloy surface wear resistant CrZrN solid solution ceramic coating of claim 6, wherein, The diffusion layer has a thickness of 1 μm.

8. The TC4 alloy surface wear resistant CrZrN solid solution ceramic coating according to claim 6 or 7, characterized in that, The deposition layer has a thickness of 6 μm.

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