Wear-resistant and corrosion-resistant graphene composite ceramic coating and preparation method thereof

Abstract

The invention relates to a wear-resistant and corrosion-resistant graphene composite ceramic coating and a preparation method thereof.The preparation method comprises the steps that firstly, anhydrous sodium metaaluminate, anhydrous trisodium phosphate, potassium fluoride, sodium hydroxide, graphene, a graphene dispersing agent and water serve as raw materials to prepare micro-arc oxidation electrolyte, and then a micro-arc oxidation method is adopted for electrolysis to prepare a Ti6Al4V alloy sample with the coating; and finally, the Ti6Al4V alloy sample with the coating is subjected to ultrasonic cleaning and drying, and the wear-resistant and corrosion-resistant graphene composite ceramic coating is prepared on the Ti6Al4V alloy sample. The wear-resistant and corrosion-resistant graphene composite ceramic coating is of a porous structure, the pore diameter is 1-3 microns, the porosity is 4%, and the wear-resistant and corrosion-resistant performance of the surface of the coating is superior to that of titanium alloy; through detection, the surface hardness of the graphene composite ceramic coating reaches 813 HV, the tensile strength is improved to 41.29 MPa, and the graphene composite ceramic coating has excellent wear resistance and corrosion resistance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of composite coating and particularly relates to a wear-resistant and corrosion-resistant graphene composite ceramic coating and a preparation method thereof. BACKGROUND

[0002] Titanium and titanium alloy have high specific strength, excellent corrosion resistance and good high-temperature performance, etc., and are emerging structural and functional materials. At present, they are mainly used in the fields of aerospace, navigation, petroleum, chemical industry, light industry, metallurgy, automobile, construction and medicine, etc. However, the common shortcomings of titanium alloy are low hardness and poor wear resistance. The hardness of pure titanium is about 150-200 Hv, and the hardness of titanium alloy is usually not more than 350 Hv. Such hardness values cannot meet the requirements of actual production application in many cases. There are two ways to improve the wear resistance of titanium alloy: alloying or surface modification. Since the cost of alloying is high, the method of surface modification has attracted more and more attention.

[0003] Surface modification technology provides an effective and feasible solution to the above limitations. Among them, micro-arc oxidation technology is a kind of plasma electrolytic oxidation process, which has the characteristics of simple process, low cost, efficient processing, strong controllability, green environmental protection, etc., and has attracted much attention in the surface protection of light alloy, and has reached the industrialization level. By simply immersing the Ti6Al4V substrate into the electrolyte and generating an electrochemical reaction, the micro-arc oxidation technology can form a hard ceramic coating on the surface of the substrate. These ceramic coatings exhibit high surface hardness, excellent wear resistance and corrosion resistance. In addition, unlike some physical vapor deposition and chemical vapor deposition coatings, the growth of micro-arc oxidation coating is a substrate transformation process rather than an external deposition. There is no artificial interface between the substrate and the coating. This makes the coating and the substrate tightly combined, with good adhesion strength and long service life. The unique advantages of the above-mentioned micro-arc oxidation technology make it popular in the surface protection of Ti6Al4V substrate, and have good potential and broad prospects in improving the fretting corrosion performance.

[0004] Titanium alloy with micro-arc oxidation coating is widely used in national defense, national economy and chemical industry. Therefore, the performance requirements of titanium alloy with micro-arc oxidation coating are high, not only excellent corrosion resistance and surface appearance quality, but also certain wear resistance to meet the environment of various possible applications. However, the micro-arc oxidation coating prepared in the prior art has many micro-defects, resulting in large brittleness of the coating structure, poor wear resistance, easy falling off, and easy corrosion, which restricts the performance and use range of the coating. Therefore, how to prepare a micro-arc oxidation technology-based coating with corrosion resistance, high hardness and not easy to fall off is particularly important. SUMMARY

[0005] In order to solve the above problems existing in the prior art, the application provides a wear-resistant and corrosion-resistant graphene composite ceramic coating and a preparation method thereof.The wear-resistant and corrosion-resistant graphene composite ceramic coating is a nano composite coating composed of C, anatase TiO2, rutile TiO2 and Al2TiO5, namely a Ti-C / TiO2 / Al2TiO5 composite coating, the composite coating has a porous structure, the pore diameter is 1-3 mu m, the porosity is 4%, and the wear-resistant and corrosion-resistant performance of the coating surface is better than that of a titanium alloy, the hardness is high, and the wear resistance is good.

[0006] The technical scheme adopted by the application is as follows: A preparation method of a wear-resistant and corrosion-resistant graphene composite ceramic coating comprises the following steps: (1) preparing a micro-arc oxidation electrolyte The raw material composition of the micro-arc oxidation electrolyte comprises anhydrous sodium metaaluminate (NaAlO2), anhydrous trisodium phosphate (Na3PO4), potassium fluoride (KF), sodium hydroxide (NaOH), graphene, a graphene dispersant and water. (2) preparing a micro-arc oxidation coating The micro-arc oxidation electrolyte in step (1) is used as an electrolyte, an alloy sample is used as an anode, a stainless steel electrolytic cell is used as a cathode, and a constant current mode is used for micro-arc oxidation electrolysis to prepare an alloy sample with a coating. (3) cleaning and drying treatment The alloy sample with the coating in step (2) is cleaned and dried, that is, a wear-resistant and corrosion-resistant graphene composite ceramic coating is prepared on the alloy sample.

[0007] The alloy sample is a Ti6Al4V alloy sample. The alloy base sample is pretreated, and the specific operation is that the Ti6Al4V alloy sample is drilled in the center and then the sample is ultrasonically cleaned in anhydrous ethanol.

[0008] The micro-arc oxidation electrolyte is an alkaline system.

[0009] The pH value of the micro-arc oxidation electrolyte is 10-12.

[0010] The concentrations of the substances in the micro-arc oxidation electrolyte are as follows: 0.1-20 g / L of sodium metaaluminate, 0.1-5 g / L of trisodium phosphate, 0.1-4 g / L of potassium fluoride, 0.1-2 g / L of sodium hydroxide, 0-30 mg / L of graphene and 0-2 g / L of a graphene dispersant.

[0011] The concentrations of the substances in the micro-arc oxidation electrolyte are respectively: 12.5 g / L of sodium metaaluminate, 1.9 g / L of trisodium phosphate, 1.5 g / L of potassium fluoride, 2 g / L of sodium hydroxide, 20 mg / L of graphene, and 1.5 g / L of graphene dispersant.

[0012] The graphene dispersant is any one or a combination of several of poly sorbate 80 (TW80), SDBS, SHMP, EDTA-2Na, and DMF.

[0013] In step (2), the specific conditions of the electrolysis are: a current density of 6 A / dm 2 , a pulse frequency of 200 Hz, a duty cycle of 30%, and an electrolytic oxidation time of 15-35 min.

[0014] In step (3), the alloy sample with the coating is placed in anhydrous ethanol for ultrasonic cleaning.

[0015] The preparation method prepares a wear-resistant and corrosion-resistant graphene composite ceramic coating.

[0016] The present application has the following beneficial effects: The present application provides a preparation method of a wear-resistant and corrosion-resistant graphene composite ceramic coating. First, anhydrous sodium metaaluminate (NaAlO2), anhydrous trisodium phosphate (Na3PO4), potassium fluoride (KF), sodium hydroxide (NaOH), graphene, graphene dispersant, and water are used as raw materials to prepare a micro-arc oxidation electrolyte. Then, a Ti6Al4V alloy sample with a coating is prepared by electrolysis using a micro-arc oxidation method. Finally, the Ti6Al4V alloy sample with the coating is ultrasonically cleaned and dried to prepare a wear-resistant and corrosion-resistant graphene composite ceramic coating on the Ti6Al4V alloy sample. The wear-resistant and corrosion-resistant graphene composite ceramic coating is a nano composite coating composed of C, anatase TiO2, rutile TiO2, and Al2TiO5, i.e., a Ti-C / TiO2 / Al2TiO5 composite coating. The composite coating has a porous structure with a pore size of 1-3 μm and a porosity of 4%. The wear-resistant and corrosion-resistant performance of the coating surface is superior to that of a titanium alloy. The surface hardness of the graphene composite ceramic coating is up to 813 HV, the tensile strength is increased to 41.29 MPa, and the graphene composite ceramic coating has excellent wear resistance and corrosion resistance. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0018] Figure 1 SEM images of the wear-resistant and corrosion-resistant graphene composite ceramic coating described in embodiments 1-6 of the present application; Figure 2 Surface feature detection images of the wear-resistant and corrosion-resistant graphene composite ceramic coating described in embodiments 1-6 of the present application; Figure 3 X-ray diffraction images of the wear-resistant and corrosion-resistant graphene composite ceramic coating described in embodiments 1-6 of the present application; Figure 4 Film layer mass spectrum images of the wear-resistant and corrosion-resistant graphene composite ceramic coating described in embodiment 4 of the present application; Figure 5 Film layer negative ion 3D depth profiling of the wear-resistant and corrosion-resistant graphene composite ceramic coating described in embodiments 1, 4, and 6 of the present application; Figure 6 Mechanical property detection images of the wear-resistant and corrosion-resistant graphene composite ceramic coating described in embodiments 1-6 of the present application; Figure 7 Micron scratch test results of the wear-resistant and corrosion-resistant graphene composite ceramic coating described in embodiments 1-6 of the present application; wherein the left image is the load-indentation depth curve of the micron scratch test, and the right image is the scratch morphology image; Figure 8 Tensile test results of the wear-resistant and corrosion-resistant graphene composite ceramic coating described in embodiments 1-6 of the present application; wherein the left image is the displacement-load curve of the tensile test, and the right image is the fracture image; Figure 9 Friction and wear property detection images of the wear-resistant and corrosion-resistant graphene composite ceramic coating described in embodiments 1-6 of the present application; wherein the left image is the friction coefficient curve, and the right image is the comparison of wear scar width, depth, and wear rate; Figure 10 Wear scar 3D morphology images of the wear-resistant and corrosion-resistant graphene composite ceramic coating described in embodiments 1-6 of the present application; Figure 11 Corrosion resistance detection of the wear-resistant and corrosion-resistant graphene composite ceramic coating described in embodiments 1-6 of the present application; wherein the left image is the open circuit potential, and the right image is the polarization curve. DETAILED DESCRIPTION

[0019] In order to make the objectives, technical solutions, and advantages of the present application clearer, the technical solutions of the present application will be described in detail below. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of the present application.

[0020] Example 1 The embodiment provides a preparation method of a wear-resistant and corrosion-resistant graphene composite ceramic coating, and the coating is a Ti-C / TiO2 / Al2TiO5 composite coating, and specifically comprises the following steps: (1) sample pretreatment A Ti6Al4V alloy test block is taken, and the processing process is cutting-drilling-polishing-decontamination. The cutting size is 20 mm*10 mm*10 mm, the surface of the test block is polished to be smooth and flat by using 60#, 400#, 600#, 800# and 1000# sandpaper, and then the test block is placed into an ethanol solution for ultrasonic treatment for 15 min and dried.

[0021] (2) preparation of micro-arc oxidation electrolyte Analytically pure anhydrous sodium metaaluminate, anhydrous trisodium phosphate, potassium fluoride, sodium hydroxide, graphene, TW80 and water are taken to prepare a micro-arc oxidation electrolyte, and the concentrations of the substances are as follows: 12.5 g / L of sodium metaaluminate, 1.9 g / L of trisodium phosphate, 1.5 g / L of potassium fluoride, 2 g / L of sodium hydroxide, 0 mg / L of graphene and 1.5 g / L of TW80. The sodium hydroxide is used for adjusting the pH value of the solution to be alkaline. In the embodiment, the pH value of the micro-arc oxidation electrolyte is 10. (3) preparation of a micro-arc oxidation coating A JHMA220-10A type portable micro-arc oxidation power supply and a cylindrical stainless steel electrolytic cell with a diameter of 300 mm are used.

[0022] The micro-arc oxidation electrolyte in step (2) is used as the electrolyte, the Ti6Al4V alloy test sample is used as the anode, and the stainless steel electrolytic cell is used as the cathode. A mechanical stirrer is arranged in the electrolytic cell, and an external water cooling device is arranged. The electrolysis is carried out in a constant current mode, the current density is 6 A / dm 2 , the pulse frequency is 200 Hz, the duty cycle is 30%, and the electrolytic oxidation time is 25 min, so that the alloy test sample with the coating is prepared. (3) cleaning and drying treatment The alloy test sample with the coating in step (2) is placed into anhydrous ethanol for ultrasonic cleaning, so that the wear-resistant and corrosion-resistant graphene composite ceramic coating is prepared on the alloy test sample, and the alloy test sample is stored in a sterile drying box.

[0023] Example 2 The embodiment provides a preparation method of a wear-resistant and corrosion-resistant graphene composite ceramic coating, and the difference from the embodiment 1 is that the concentration of graphene in the micro-arc oxidation electrolyte is 1 mg / L, and the electrolytic oxidation time is 15 min when the micro-arc oxidation coating is prepared.

[0024] Example 3 The embodiment provides a preparation method of the wear-resistant and corrosion-resistant graphene composite ceramic coating, and only differs from the embodiment 1 in that the graphene concentration in the micro-arc oxidation electrolyte is 5 mg / L; and the pH value of the micro-arc oxidation electrolyte is 11.

[0025] Embodiment 4 The embodiment provides a preparation method of the wear-resistant and corrosion-resistant graphene composite ceramic coating, and only differs from the embodiment 1 in that the graphene concentration in the micro-arc oxidation electrolyte is 10 mg / L; and the pH value of the micro-arc oxidation electrolyte is 12.

[0026] Embodiment 5 The embodiment provides a preparation method of the wear-resistant and corrosion-resistant graphene composite ceramic coating, and only differs from the embodiment 1 in that the graphene concentration in the micro-arc oxidation electrolyte is 20 mg / L, and the electrolytic oxidation time is 35 min when the micro-arc oxidation coating is prepared.

[0027] Embodiment 6 The embodiment provides a preparation method of the wear-resistant and corrosion-resistant graphene composite ceramic coating, and only differs from the embodiment 1 in that the graphene concentration in the micro-arc oxidation electrolyte is 30 mg / L.

[0028] Experimental example The surface morphology of the wear-resistant and corrosion-resistant graphene composite ceramic coatings obtained in the embodiments 1-6 is characterized, as shown in the following table. Figure 1 Figure 1 In the table, G0-G30 respectively correspond to the wear-resistant and corrosion-resistant graphene composite ceramic coatings obtained in the embodiments 1-6. As can be seen from the table, the coating has a porous structure, and the pore diameter is 1-3 μm.

[0029] Further, the thickness, roughness and porosity of the wear-resistant and corrosion-resistant graphene composite ceramic coatings obtained in the embodiments 1-6 are characterized, as shown in the following table. Figure 2 As can be seen from the table, the porosity of the wear-resistant and corrosion-resistant graphene composite ceramic coating obtained in the embodiment 5 (G20) is 4%.

[0030] Figure 3 The X-ray diffraction patterns of the wear-resistant and corrosion-resistant graphene composite ceramic coatings obtained in the embodiments 1-6 are shown in the following table, and as can be seen from the table, the coating is mainly composed of an aluminum titanate phase, and the content of the aluminum titanate phase first increases and then decreases with the increase of the graphene addition amount, and the content is the largest when the graphene addition amount is 20 mg / L.

[0031] The TOF-SIMS analysis method is used to measure the spectra of positive ions and negative ions of the coating in the embodiment 4 (G10), and the mass spectrum is as shown in the following table. Figure 4 ​As shown, in the positive spectrum data, elements including Na, Al, K, Ti and metal and oxides such as AlO, TiO, AlTiO, etc. are detected, while in the negative spectrum data, non-metal elements and oxides such as O, F, OH, AlO2, PO2, PO3, TiO2, etc. are detected.

[0032] The TOF-SIMS negative ion depth profiling of the three groups of coating samples (G0, G10, G30) obtained in Examples 1, 4 and 6 was performed, and the ion three-dimensional depth distribution diagram drawn is as shown in Figure 5 As shown, TiO2 is uniformly distributed in the three groups of samples, and the signal intensity is similar, indicating that the Ti element always exists in a stable oxidation state in the entire film layer. The depth distribution of C-related ions further reveals the existence mode of graphene in the film layer.

[0033] The mechanical properties of the wear-resistant and corrosion-resistant graphene composite ceramic coating obtained in Examples 1-6 were detected, and the results are as shown in Figure 6 As shown, with the increase of the concentration of graphene, the hardness of the coating gradually increases. When the concentration of graphene is 20 mg / L, the surface hardness reaches 813 HV, which is about 12% higher than that without adding graphene.

[0034] The micron scratch test results are as shown in Figure 7 As can be seen from the figure, the addition of graphene improves the interfacial bonding strength between the coating and the substrate. When the addition amount of graphene is 10-20 mg / L, the critical peeling load is increased by 30% compared with that without adding graphene.

[0035] Combined with the displacement-load curve and fracture morphology analysis of the tensile test, as shown in Figure 8 The film-substrate interface shows brittle fracture characteristics, and when no graphene is added, the tensile strength is only 14.11 MPa; while when the addition amount of graphene is 10 mg / L (Example 4), the bonding force is increased to 41.29 MPa.

[0036] The friction and wear properties of the composite coatings (G0, G1, G5, G10, G20, G30) described in Examples 1-6 with different addition amounts of graphene were tested using silicon nitride (Si3N4) and pure aluminum grinding heads, and the friction coefficient curves and wear rates are as shown in Figure 9

[0037] When using a silicon nitride grinding head, the friction coefficients of each group of samples are relatively stable, but the samples of Example 1 (G0) and Example 6 (G30) show obvious step mutations during the test, indicating that the coating is worn out and enters the substrate wear stage; the curves of the remaining samples are relatively stable, showing that the coating structure is relatively stable. When the addition amount of graphene is 0 mg / L (G0), the wear rate is 4.03×10 - 4 mm 3 ​(N•m); the wear rate was the smallest, 2.31 x 10 -4 mm 3 (N•m) when the additive amount was 30 mg / L, the coating lost the protection ability, the substrate was worn, the wear rate increased to 3.48 x 10 -4 mm 3 (N•m), accompanied by groove and abrasive wear. When the pure aluminum grinding head was used, the noise of the friction coefficient curve of each group of samples was large, especially in the middle and late stages. The wear rate showed a downward trend with the increase of the additive amount of graphene, but the change trend was similar: the wear rate was 6.51 x 10 -4 mm 3 (N•m) when the additive amount was 0 mg / L (G0), the wear rate was 2.93 x 10 -4 mm 3 (N•m) when the additive amount was 30 mg / L (G30).

[0038] The corrosion resistance of the wear-resistant and corrosion-resistant graphene composite ceramic coating described in embodiments 1-6 of the application was detected, specifically: Open position voltage: as shown in Figure 11 , the open-circuit potential of the titanium alloy substrate and the micro-arc oxidation coating with different graphene contents in 3.5 wt.% NaCl solution changed with time. The open-circuit potential of the substrate was about -0.057 V finally, the micro-arc oxidation coating (G0) maintained a relatively stable potential of 0.274 V from the beginning of the test, which was significantly higher than that of the substrate; after adding graphene, the stable potential of the composite coating was all higher than 0.33 V.

[0039] Polarization curve: in the simulated seawater solution, the potentiodynamic polarization curve was measured as shown in Figure 11 , the self-corrosion potential (Ecorr), self-corrosion current density (Icorr) and anode / cathode slope (B and B, respectively) of the sample were obtained by Tafel linear extrapolation method, and the polarization resistance (Rp) of each group of samples was calculated by using Stern-Ceary equation, and the corresponding Tafel data are listed in Table 1 below.

[0040] Table 1 - Polarization curve test results As can be seen from the table, the corrosion current density (Icorr) of the substrate was the highest, 2.03 x 10 -7 A·cm -2 , and the Icorr of all the coating samples was all in the order of 10 -8 A·cm -2The results show that the corrosion resistance of the micro-arc oxidation coating is significantly improved. The G0 sample without graphene shows a significant improvement. The performance increases first and then decreases with the further addition of graphene. The Icorr of G20 is the lowest (1.98×10 -8 A·cm -2 ), and the polarization resistance is the highest (2.22×10 6 Ω·cm 2 ), which shows the best corrosion resistance. Excessive graphene (G30) causes a slight decline in performance, but it is still better than TC4 and G0.

[0041] The above merely describes the specific embodiments of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method of preparing a wear and corrosion resistant graphene composite ceramic coating, characterized by, It comprises the following steps: (1) preparing a micro-arc oxidation electrolyte The raw material composition of the micro-arc oxidation electrolyte is: anhydrous sodium metaaluminate, anhydrous trisodium phosphate, potassium fluoride, sodium hydroxide, graphene, graphene dispersant and water; (2) preparing a micro-arc oxidation coating The micro-arc oxidation electrolyte of step (1) is used as the electrolyte, the alloy sample is used as the anode, the stainless steel electrolytic cell is used as the cathode, and electrolysis is carried out in a constant current mode to obtain an alloy sample with a coating. (3) cleaning and drying treatment The alloy sample with a coating of step (2) is cleaned and dried, i.e. a wear-resistant and corrosion-resistant graphene composite ceramic coating is prepared on the alloy sample.

2. The method of claim 1, wherein the method further comprises the step of: The alloy sample is a Ti6Al4V alloy sample. First, the alloy substrate sample is pretreated, and the specific operation is: the Ti6Al4V alloy sample is drilled in the center, and then the sample is ultrasonically cleaned in anhydrous ethanol.

3. The method of claim 1, wherein the method further comprises the step of: The micro-arc oxidation electrolyte is an alkaline system.

4. The method of claim 3, wherein the graphene composite ceramic coating is prepared by a process comprising: The pH value of the micro-arc oxidation electrolyte is 10-12.

5. The method for preparing the wear-resistant and corrosion-resistant graphene composite ceramic coating according to claim 1, characterized in that, The concentrations of the substances in the micro-arc oxidation electrolyte are: 0.1-20 g / L of sodium metaaluminate, 0.1-5 g / L of trisodium phosphate, 0.1-4 g / L of potassium fluoride, 0.1-2 g / L of sodium hydroxide, 0-30 mg / L of graphene, and 0-2 g / L of graphene dispersant.

6. The method of claim 5, wherein the graphene composite ceramic coating is prepared by a process comprising: The concentrations of the substances in the micro-arc oxidation electrolyte are: 12.5 g / L of sodium metaaluminate, 1.9 g / L of trisodium phosphate, 1.5 g / L of potassium fluoride, 2 g / L of sodium hydroxide, 20 mg / L of graphene, and 1.5 g / L of graphene dispersant.

7. The method for preparing the wear-resistant and corrosion-resistant graphene composite ceramic coating according to claim 1, characterized in that, The graphene dispersant is any one or a combination of several of polysorbate 80, SDBS, SHMP, EDTA-2Na and DMF.

8. The method for preparing the wear-resistant and corrosion-resistant graphene composite ceramic coating according to claim 1, characterized in that, In step (2), the specific conditions of the electrolysis are: current density 6 A / dm 2 , pulse frequency 200 Hz, duty cycle 30 %, electrolytic oxidation time 15-35 min.

9. The method for preparing the wear-resistant and corrosion-resistant graphene composite ceramic coating according to claim 1, characterized in that, In step (3), the alloy sample with a coating is placed in anhydrous ethanol for ultrasonic cleaning.

10. The wear-resistant and corrosion-resistant graphene composite ceramic coating prepared by the preparation method of any one of claims 1-9.

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