Preparation method and application of graphene / titanium alloy electron beam cladding coating for inhibiting generation of TiC

Abstract

The invention discloses a preparation method and application of a graphene / titanium alloy electron beam cladding coating for inhibiting generation of TiC, and belongs to the technical field of titanium-based composite materials and preparation thereof. The method solves the technical problem that a TiC phase is easily generated in situ when the titanium alloy is subjected to surface enhancement by the existing graphene. According to the preparation method, the reaction of graphene and titanium alloy is inhibited through SiC, a C-Ti reaction path is inhibited from the source, and meanwhile, the depth of a molten pool is regulated and controlled by regulating and controlling electron beam current parameters, so that the dilution rate of the C element is controlled, the C element is subjected to complete solid solution in a matrix, TiC is not generated, TiC-phase-free coating preparation is realized, a graphene lamellar structure is completely reserved, and the preparation process is simple. The core advantages of self-lubrication and high mechanical strength are brought into full play, and the coating performance damage caused by TiC generation is avoided.

Description

TECHNICAL FIELD

[0001] The application relates to a preparation method and application of a graphene / titanium alloy electron beam cladding coating for inhibiting TiC generation and belongs to the technical field of titanium-based composite materials and preparation thereof. BACKGROUND

[0002] Titanium alloys have been widely applied in aerospace engineering, automobile manufacturing, biomedical engineering, high-end equipment manufacturing and other fields due to their low density, high strength, excellent corrosion resistance and biocompatibility. However, the titanium alloy surface has low hardness and poor wear resistance, and is prone to surface damage under service conditions such as sliding friction and impact wear, which seriously limits its further application in scenes with strict requirements for surface wear resistance. Therefore, surface modification treatment of titanium alloys to improve their surface wear resistance has become an important research direction in the field of titanium alloy materials. Among many surface modification technologies, cladding technology is widely used because it can form a high-performance coating on the surface of the substrate, which is metallurgically combined with the substrate and significantly improves the surface performance. With the development of nanomaterial technology, graphene, as a two-dimensional nanomaterial with excellent mechanical strength, ultra-high thermal conductivity and unique self-lubricating performance, has become an ideal reinforcing phase for metal matrix composites due to its outstanding performance advantages. The introduction of graphene into the surface coating of titanium alloys is expected to prepare a composite coating with high strength, low friction coefficient and high wear resistance, thereby solving the problem of insufficient wear resistance of titanium alloy surfaces. However, when graphene is used to enhance the surface of titanium alloys in the prior art, there are key technical bottlenecks: during high-temperature treatment such as cladding, the C element in graphene is prone to chemical reaction with the Ti element in the titanium matrix, generating TiC phase in situ. The generation of TiC phase not only destroys the integrity of the graphene layer structure, making it lose its excellent self-lubricating performance and mechanical reinforcement effect, but also may cause cracks in the coating and reduce the bonding force due to the brittleness of TiC, thereby affecting the overall wear resistance and service stability of the coating. To solve this problem, existing research attempts to inhibit TiC generation by adjusting the cladding temperature and shortening the high-temperature residence time, but the effect is limited and it is difficult to completely avoid the reaction; some researches also use the addition of other elements as a barrier phase, but often introduce impurity phases. Therefore, developing a titanium alloy surface coating preparation technology that can effectively inhibit the reaction between graphene and titanium matrix to generate TiC and ensure that the excellent performance of graphene can be fully utilized is of great significance for promoting the engineering application of graphene reinforced titanium alloy composites, and is also a technical problem to be solved in the current field. SUMMARY

[0003] The application aims at the technical problem that TiC phase is prone to be generated in situ when existing graphene is used to enhance the surface of titanium alloy, and provides a preparation method and application of graphene / titanium alloy electron beam cladding coating for inhibiting TiC generation, which introduces SiC and simultaneously controls electron beam current parameters, so that C elements in graphene are completely solid-solved into the titanium alloy matrix, the generation of in-situ TiC in the composite coating is prevented, and the method and its application for significantly improving the wear resistance of the titanium alloy surface.

[0004] The technical scheme of the application is as follows: One of the purposes of the application is to provide a preparation method of graphene / titanium alloy electron beam cladding coating for inhibiting TiC generation, which comprises the following steps: S1: dispersing graphene and SiC nano powder in a polyvinyl alcohol aqueous solution, stirring uniformly to obtain a stable composite coating liquid, uniformly coating the composite coating liquid on the surface of a titanium alloy matrix, and drying to form a pre-coating layer; S2: performing electron beam cladding treatment on the titanium alloy matrix with the pre-coating layer, and naturally cooling after the cladding is completed to obtain a coating.

[0005] Further limitation, the particle size of the SiC nano powder is 30-50 nm, and the amount is 30 wt.% of the graphene.

[0006] Further limitation, the graphene content in the composite coating liquid is 4 wt.%, and the particle size is 5-10 μm.

[0007] Further limitation, the polyvinyl alcohol content in the composite coating liquid is 5 wt.%, the molecular weight is 1700 Da, and the alcoholysis degree is 99%.

[0008] Further limitation, the dispersion mode is a combination of ultrasonic dispersion and mechanical stirring, the ultrasonic time is 30 min, and the mechanical stirring speed is 300-800 r / min.

[0009] Further limitation, the thickness of the pre-coating layer is 0.5-2 mm.

[0010] Further limitation, the composite coating liquid is uniformly coated on the surface of the titanium alloy matrix by using a brushing coating mode.

[0011] Further limitation, the current of the electron beam cladding treatment is 20-45 mA, the scanning speed is 600 mm / min, the electron beam voltage is 60 kV, the electron beam focal length is 60 mm, and the environment is an argon protective atmosphere.

[0012] Further limitation, the depth of the molten pool in the electron beam cladding treatment process is greater than 2 mm.

[0013] Further limitation, the titanium alloy matrix is TC4, TC6 or TC11.

[0014] Further limit, before the titanium alloy base is coated, polishing, oil removal, rust removal and drying treatment.

[0015] Further limit, before the titanium alloy base is coated, polishing, oil removal, rust removal and drying treatment.

[0016] The second object of the present application is to provide a coating obtained by the above preparation method, wherein the graphene is uniformly distributed, there is no TiC phase, and the friction coefficient is ≤0.3.

[0017] The third object of the present application is to provide an application of the above coating in aerospace component manufacturing, automobile manufacturing and biomedical engineering.

[0018] Advantages: The present application inhibits the reaction of graphene and titanium alloy by SiC, inhibits the C-Ti reaction path from the source, and regulates the electron beam current parameter to regulate the depth of the molten pool, thereby controlling the dilution rate of C element to make it completely solid-soluted in the base without generating TiC, realizing the preparation of TiC-free coating, and then retaining the complete graphene sheet structure, fully exerting the core advantages of self-lubrication and high mechanical strength, and avoiding the performance loss of the coating due to the generation of TiC. Compared with the prior art, the present application has the following advantages: (1) The friction coefficient of the coating prepared by the present application is significantly reduced, the friction coefficient of the coating is ≤0.3, which is much lower than that of the existing TiC reinforced titanium alloy coating and titanium alloy base (usually ≥0.4), the self-lubrication effect is outstanding, and the wear resistance is improved in a leap. And the coating and the titanium alloy base form a firm metallurgical bond, without the risk of cracking and falling off, and because there is no brittle TiC phase, the toughness and service reliability of the coating are significantly better than those of the prior art.

[0019] (2) The method for inhibiting the generation of TiC provided by the present application avoids the problems of limited effect or introduction of side effects compared with the existing technology for inhibiting TiC (such as reducing temperature and adding impurity elements). And the coating preparation process steps provided by the present application are clear, the parameters of the composite coating liquid preparation, pre-coating and electron beam cladding are easy to control, no complex equipment modification is needed, and no harmful impurity phase is introduced, and the Si and C elements in SiC are completely solid-soluted in the base. Compared with the prior art, the present application is simple to operate, the cost is controllable, and it is easier to realize large-scale production, and solves the key obstacles of engineering application of graphene reinforced titanium alloy composite materials.

[0020] (3) The composite coating prepared by the application not only retains the original advantages of titanium alloy, such as low density and high corrosion resistance, but also makes up for the short board of insufficient surface wear resistance. Compared with the prior art, the coating can adapt to the high wear working condition requirements in the fields of aerospace, automobile manufacturing, biomedicine and the like, significantly widens the application boundary of titanium alloy in high-end equipment manufacturing, precision machinery and other scenes with strict requirements on surface performance, and has important engineering value and market prospect. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 Raman spectrum of the composite coating obtained in Example 1; Figure 2 Raman spectrum of the composite coating obtained in Comparative Example 1; Figure 3 Scanning electron microscope image of the composite coating obtained in Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0022] In order to make the above-mentioned purposes, features and advantages of the application more obvious and easy to understand, the specific embodiments of the application will be described in detail below with reference to the embodiments of the specification.

[0023] In the following description, a large number of specific details are set forth in order to facilitate a thorough understanding of the application, but the application can also be implemented in other ways different from those described herein, and those skilled in the art can make similar generalizations without departing from the connotation of the application, therefore the application is not limited by the specific embodiments disclosed below.

[0024] Secondly, "one embodiment" or "embodiment" referred to herein means that a specific feature, structure or characteristic can be included in at least one implementation of the application. "In one embodiment" appearing in different places in the specification does not mean the same embodiment, nor is it an embodiment that is separate or alternative to other embodiments.

[0025] The experimental methods used in the following examples are all conventional methods unless otherwise specified. The materials, reagents, methods and instruments used are all conventional materials, reagents, methods and instruments in the art unless otherwise specified, and can be obtained by commercial channels by those skilled in the art.

[0026] In the following examples and comparative examples, the mass of graphene is 0.4% of the sum of the mass of TC4 and the mass of graphene. The particle size of SiC nanoparticles is 30-50 nm. The graphene is few-layer graphene with a particle size of 5-10 μm. The molecular weight of polyvinyl alcohol is 1700 Da, and the alcoholysis degree is 99%.

[0027] Example 1: The method for preparing the composite coating on the surface of the TC4 plate in this embodiment includes the following steps: (1) SiC nanoparticles, graphene powder, polyvinyl alcohol particles and water were weighed by an electronic balance, and ultrasonic dispersion and mechanical stirring were performed for 30 min at a mass ratio of 1.2:4:5:89.8 to obtain a mixed solution of 100 ml; (2) The mixed solution was brushed on the surface of a 20x20x2 cm 3 TC4 plate with a brush, and dried at a temperature of 60 ℃ for 24 h to form a film, thereby obtaining a pre-coating layer; (3) The TC4 plate coated with the pre-coating layer was subjected to cladding treatment by a vacuum resistance beam welding machine, the electron beam voltage was 60 kV, the current was 35 mA, the scanning speed was 600 mm / min, the spot diameter was 5 mm, and the TC4 plate was taken out after cooling for 10 min, thereby obtaining a composite coating on the TC4 plate.

[0028] Figure 1 The Raman spectrum of the composite coating prepared in the embodiment is shown in the figure, and it can be seen from the figure that the intensity ratio (I D / I G ) of the D peak and the G peak of graphene is low, and the graphene structure is complete.

[0029] The scanning electron microscope results of the cross section are shown in Figure 2 , and it can be seen from the figure that the thickness of the composite coating is about 2 mm, there is no TiC phase in the coating, Si and C elements are completely solid-solved, graphene exists in large quantities in the coating, the structure is complete, and the layered structure characteristics are obvious.

[0030] The composite coating surface obtained in the embodiment was subjected to pin-on-disk friction and wear test under the conditions of a Cr12MoV steel friction disc, a load of 50 N, a rotating speed of 200 r / min, and a friction diameter of 24 mm, and the test results showed that the average friction coefficient was about 0.3.

[0031] Comparative Example 1 The method for preparing a composite coating on the surface of a TC4 plate in the comparative example comprises the following steps: (1) SiC nanoparticles, graphene powder, polyvinyl alcohol particles and water were weighed by an electronic balance, and ultrasonic dispersion and mechanical stirring were performed for 30 min at a mass ratio of 1.2:4:5:89.8 to obtain a mixed solution of 100 ml; (2) The solution was placed on the surface of a 20x20x2 cm 3 TC4 plate with a brush, and dried at a temperature of 60 ℃ for 24 h to form a film; (3) The TC4 plate coated with graphene was subjected to cladding treatment by a vacuum resistance beam welding machine, the electron beam voltage was 60 kV, the current was 15 mA, the scanning speed was 600 mm / min, the spot diameter was 5 mm, and the TC4 plate was taken out after cooling for 10 min, thereby obtaining a composite coating on the TC4 plate.

[0032] Figure 2 The Raman spectrum of the composite coating prepared for the present comparative example is shown in the figure, and it can be seen from the figure that the intensity ratio (I D / I G ) of the D peak and the G peak of the graphene is low, and the graphene structure is complete.

[0033] The scanning electron microscope result of the section is shown in the figure Figure 2 , and it can be seen from the figure that the thickness of the composite coating is 0.2 mm, and a large amount of TiC and unvolatile polyvinyl alcohol exist in the coating.

[0034] The pin-on-disk friction and wear test was carried out on the surface of the composite coating obtained in the present comparative example under the condition of a Cr12MoV steel as a friction disc, a load of 50 N, a rotating speed of 200 r / min and a friction diameter of 24 mm, and the test result showed that the average friction coefficient was about 0.4.

[0035] Comparative Example 2 The pin-on-disk friction and wear test was carried out on the surface of the TC4 plate without surface coating under the condition of a Cr12MoV steel as a friction disc, a load of 50 N, a rotating speed of 200 r / min and a friction diameter of 24 mm, and the test result showed that the average friction coefficient was about 0.5.

[0036] The above only describes the preferred embodiments of the present application, and the above-mentioned embodiments can be appropriately changed and modified by those skilled in the art to which the present application belongs, therefore, the present application is not limited to the above-mentioned specific embodiments, and some modifications and changes of the present application should fall within the protection scope of the claims of the present application.

Claims

1. A method for preparing a graphene / titanium alloy electron beam cladding coating that inhibits TiC formation, characterized in that, include: S1: Graphene and SiC nanopowder are dispersed in an aqueous solution of polyvinyl alcohol and stirred evenly to obtain a stable composite coating solution. The composite coating solution is then uniformly coated on the surface of a titanium alloy substrate and dried to form a pre-coating layer. S2: Electron beam cladding is performed on a titanium alloy substrate with a pre-coated layer. After cladding, the substrate is allowed to cool naturally to obtain the coating.

2. The preparation method according to claim 1, characterized in that, The particle size of SiC nanoparticles is 30-50 nm, and the amount used is 30 wt. of graphene.

3. The preparation method according to claim 1, characterized in that, The composite coating solution contains 4 wt.% graphene with a particle size of 5-10 μm.

4. The preparation method according to claim 1, characterized in that, The composite coating solution contains 5 wt.% polyvinyl alcohol, has a molecular weight of 1700 Da, and a degree of alcoholysis of 99%.

5. The preparation method according to claim 1, characterized in that, The dispersion method is a combination of ultrasonic dispersion and mechanical stirring. The ultrasonic time is 30 min, and the mechanical stirring speed is 300-800 r / min.

6. The preparation method according to claim 1, characterized in that, The thickness of the pre-coated layer is 0.5-2 mm.

7. The preparation method according to claim 1, characterized in that, The electron beam cladding process uses a current of 20-45 mA, a scanning speed of 600 mm / min, an electron beam voltage of 60 kV, an electron beam focal length of 60 mm, and an argon protective atmosphere.

8. The preparation method according to claim 1, characterized in that, The titanium alloy matrix is ​​TC4, TC6 or TC11.

9. A coating obtained by the preparation method according to any one of claims 1 to 6, characterized in that, The graphene in the coating is uniformly distributed, there is no TiC phase, and the friction coefficient is ≤0.

3.

10. The application of the coating of claim 9 in aerospace component manufacturing, automobile manufacturing, and biomedical engineering.

Images