Titanium alloy surface titanium carbide high-temperature oxidation-resistant wear-resistant strengthening layer and preparation method thereof

Abstract

This invention discloses a high-temperature oxidation-resistant and wear-resistant titanium carbide reinforcement layer on the surface of titanium alloys and its preparation method. This titanium carbide high-temperature oxidation-resistant and wear-resistant reinforcement layer is generated in situ on the surface of a titanium alloy substrate using nanodiamond as the carbon source. The layer is mainly composed of titanium carbide and forms a metallurgical bond with the titanium alloy substrate. Its thickness is no more than 10 μm and it is dense and uniform. This invention overcomes the bottlenecks of existing surface modification technologies, providing reliable technical support for the widespread application of titanium alloys in high-end fields such as aerospace, energy, and chemical engineering, and has significant economic and social benefits.

Description

Technical Field

[0001] This invention belongs to the field of high-temperature oxidation-resistant and wear-resistant strengthened titanium alloy manufacturing and processing technology, specifically relating to a high-temperature oxidation-resistant and wear-resistant strengthened titanium carbide layer on the surface of a titanium alloy and its preparation method. Background Technology

[0002] Titanium alloys, due to their low density, high specific strength, excellent corrosion resistance, and good biocompatibility, have been widely used in aerospace, energy, chemical, and biomedical fields. For example, in aerospace, titanium alloys are often used to manufacture critical components such as aircraft structural parts and engine components; in the energy and chemical industries, they are used in equipment such as corrosion-resistant pipes and reactors; and in the biomedical field, they are commonly used in implantable devices such as artificial joints and dental implants. These applications fully demonstrate the unique advantages of titanium alloys as lightweight, high-performance structural materials.

[0003] However, titanium alloys also have significant performance limitations, particularly their low surface hardness. Taking the commonly used Ti-6Al-4V (TC4) titanium alloy as an example, its Rockwell hardness is typically only between 30-36 HRC. This characteristic directly results in poor surface wear resistance, making it prone to surface damage under frictional conditions. Simultaneously, titanium alloys have weak oxidation resistance in medium- and high-temperature environments. At high temperatures, oxygen atoms easily diffuse into the matrix, causing the surface oxide layer to loosen and peel off, leading to a sharp decline in component performance. These defects severely restrict the long-term service reliability of titanium alloys in wear-resistant and medium- and high-temperature resistant components. For example, in high-temperature components of aero-engines or friction pairs in chemical equipment, the insufficient surface properties of titanium alloys often lead to shortened service life and increased maintenance costs, thus limiting their further promotion in high-end equipment manufacturing.

[0004] To address the aforementioned issues, surface coating technology has become a primary means of enhancing the surface properties of titanium alloys. Currently, commonly used coating techniques for titanium alloy surfaces include physical vapor deposition (PVD), chemical vapor deposition (CVD), thermal spraying, hot-dip galvanizing, laser cladding, and sputtered diamond-like carbon (DLC) coatings. While these techniques can improve the hardness, wear resistance, or oxidation resistance of titanium alloys to some extent, they generally have significant limitations. First, the equipment required for these methods is often expensive. For example, PVD and CVD equipment require precision vacuum systems and ion sources, while laser cladding relies on high-power lasers, resulting in high production costs. Second, the processes are complex, involving multi-step parameter control and special atmosphere protection, requiring highly skilled operators and making mass production and standardization difficult. More importantly, the coatings prepared by these techniques typically have low bonding strength with the titanium alloy substrate, and defects such as pores, cracks, or thermal stress concentrations easily form at the interface. Under complex operating conditions, these defects are prone to spalling failure, making it difficult to meet the stringent requirements of long-term service in high-end equipment.

[0005] In response to the aforementioned technological status quo, some improvements have been attempted in the existing technology. For example, CN 116497314A discloses a technique for preparing an oxidation-resistant and wear-resistant quaternary nitride coating on the surface of a titanium alloy substrate using an improved dual-cathode plasma surface modification metallurgical technique; CN116445842A discloses a method for forming an aluminum-magnesium oxide coating on the surface of a titanium alloy substrate by hot-dip deposition in an Al-Mg molten pool followed by oxidation treatment; CN115786905A discloses a technique for preparing an Al-Si-V-Nb wear-resistant coating using laser deposition technology; CN116180013A discloses a technique using dual-bright plasma alloying technology to... A method for preparing a high-entropy alloy reinforcement layer based on the self-diffusion of titanium-aluminum alloy using a high-entropy alloy target as the sputtering source; CN116479420A discloses a technique for forming a dense and uniform Ta reinforcement layer on the surface of a titanium alloy substrate using laser cladding technology; CN116145069A discloses a method for forming a composite coating of Ti-Al intermediate layer and pure aluminum carburized layer on the surface of a titanium alloy substrate using a combination of hot-dip aluminizing and carburizing processes; CN118086901A discloses a technique for forming a composite coating on the surface of TC4 alloy using a combination of gas etching and PVD coating.

[0006] While the aforementioned existing technologies have made some progress in specific areas, they still fail to fundamentally overcome common problems such as strong equipment dependence, complex processes, insufficient bonding strength, and high costs. These technologies either require specialized plasma / laser equipment or involve multi-step melting / deposition processes, resulting in high production barriers, narrow applicability, and difficulty in completely eliminating defects at the coating-substrate interface. In practical applications, titanium alloy components are often complex in shape and diverse in size, making it difficult for existing technologies to achieve universal strengthening for various titanium alloys (including TC4, TC6, TA2, etc.). Therefore, developing a surface modification technology that is simple to process, low in cost, has high bonding strength, stable performance, and is applicable to various complex titanium alloy components remains a key technical challenge that urgently needs to be solved in this field. This is not only related to the further exploration of the properties of titanium alloy materials but also directly affects the level of self-reliance and control in my country's high-end equipment manufacturing sector. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a high-temperature oxidation-resistant and wear-resistant strengthening layer of titanium carbide on the surface of titanium alloys.

[0008] Another objective of this invention is to provide a method for preparing the above-mentioned titanium carbide high-temperature anti-oxidation and wear-resistant strengthening layer on the surface of titanium alloy.

[0009] The technical solution of the present invention is as follows:

[0010] A high-temperature oxidation-resistant and wear-resistant titanium carbide reinforcement layer for titanium alloy surface is disclosed. The titanium carbide high-temperature oxidation-resistant and wear-resistant reinforcement layer uses nanodiamond as carbon source and is generated in situ on the surface of titanium alloy substrate under the action of a penetration aid. The titanium carbide high-temperature oxidation-resistant and wear-resistant reinforcement layer is mainly composed of titanium carbide and forms a metallurgical bond with the titanium alloy substrate. The thickness is not more than 10 μm and is dense and uniform. The penetration aid is composed of Cr powder, or Cr powder and at least one of B powder, Al powder and Ni powder.

[0011] Needle-shaped fine compounds are distributed between the titanium alloy substrate and the titanium carbide high-temperature oxidation-resistant and wear-resistant strengthening layer. The Cr element causes the surface of the nanodiamond to become amorphous, forming an amorphous layer. Both the interior of the nanodiamond and the interior of the titanium alloy substrate contain Cr-rich particles.

[0012] In a preferred embodiment of the present invention, the titanium alloy matrix is ​​TC4 titanium alloy, TC6 titanium alloy or TA2 titanium alloy.

[0013] The method for preparing the above-mentioned high-temperature oxidation-resistant and wear-resistant strengthening layer of titanium carbide on the surface of titanium alloy includes the following steps:

[0014] (1) Prepare an organic composite binder containing nanodiamonds, the organic composite binder being composed of 15-50 wt% nanodiamonds, 1-5 wt% surfactant, 3-15 wt% penetration enhancer, 13-17 wt% binder and organic solvent as the balance, the penetration enhancer being Cr powder, or being composed of Cr powder and at least one of B powder, Al powder and Ni powder;

[0015] (2) The organic composite binder containing nanodiamonds is coated on the surface of the titanium alloy substrate;

[0016] (3) Place the coated titanium alloy substrate in an oven at 100-150 ℃ for drying and curing for 5-20 min;

[0017] (4) Place the dried and cured titanium alloy substrate in a vacuum furnace and evacuate it to a vacuum level of 1×10⁻⁶. -2 The temperature is kept below Pa and under vacuum. The temperature is raised to 700-800 ℃ and held for 0.5-5 h. Then the temperature is raised to 900-1000 ℃ and held for 0.5-5 h. Finally, the temperature is cooled in the furnace to obtain the final product.

[0018] The in-situ generation mechanism in this invention is due to the fact that the main component of titanium alloy is titanium, which has good diffusion ability at high temperatures and is relatively active. On the other hand, nanodiamond has a nano effect and can easily combine with active titanium at high temperatures. Therefore, in this invention, under the action of a specific penetration aid, a slurry containing nanodiamond is coated on the surface of a titanium alloy substrate, and during high-temperature vacuum heat treatment, the titanium element and nanodiamond in the titanium alloy substrate diffuse in situ to form a high-temperature oxidation-resistant and wear-resistant strengthening layer of titanium carbide.

[0019] The Cr, B, Al, and Ni in the aforementioned penetration enhancer can synergistically promote the interdiffusion of titanium and nanodiamond. On the other hand, the penetration enhancer can also interdiffusion with elements in titanium alloys, such as Al and V in TC4 alloy, and form various fine compounds (such as TiB2) between the high-temperature oxidation-resistant and wear-resistant reinforced layer of titanium carbide and the substrate. This promotes a strong metallurgical bond between the high-temperature oxidation-resistant and wear-resistant reinforced layer of titanium carbide and the substrate, significantly improving the bonding between the high-temperature oxidation-resistant and wear-resistant reinforced layer of titanium carbide and the substrate.

[0020] In a preferred embodiment of the present invention, the nanodiamond has a particle size of 100-500 nm.

[0021] In a preferred embodiment of the present invention, the organic solvent is 3-methoxy-3-methylbutanol or N,N-dimethylacetamide.

[0022] In a preferred embodiment of the present invention, the surfactant is a silane coupling agent KH560.

[0023] In a preferred embodiment of the present invention, the penetration aid is at least one of Cr powder with a particle size of 500 nm-2 μm, B powder with a particle size of 500 nm-2 μm, Al powder with a particle size of 500 nm-2 μm, and Ni powder with a particle size of 500 nm-2 μm.

[0024] In a preferred embodiment of the invention, the adhesive is polyvinyl alcohol or polyvinylpyrrolidone.

[0025] In a preferred embodiment of the present invention, the nanodiamond has a particle size of 100-500 nm, the organic solvent is 3-methoxy-3-methylbutanol or N,N-dimethylacetamide, the surfactant is a silane coupling agent, the penetration aid is at least one of Cr powder with a particle size of 500 nm-2 μm, B powder with a particle size of 500 nm-2 μm, Al powder with a particle size of 500 nm-2 μm, and Ni powder with a particle size of 500 nm-2 μm, and the binder is polyvinyl alcohol or polyvinylpyrrolidone.

[0026] In a preferred embodiment of the present invention, the coating method in step (2) is brush coating or dip coating.

[0027] The beneficial effects of this invention are:

[0028] 1. This invention uses nanodiamond as a carbon source, combined with organic composite binder coating and vacuum heat treatment process, to form a dense and uniform high-temperature oxidation-resistant and wear-resistant titanium carbide reinforcing layer on the surface of the titanium alloy substrate in situ. It achieves a strong metallurgical bond with the substrate, effectively avoiding the interface defect problems of traditional coatings.

[0029] 2. The thickness of the high-temperature oxidation-resistant and wear-resistant reinforced titanium carbide layer formed by the present invention can be precisely controlled by heat treatment parameters, which can significantly improve the hardness and wear resistance of the titanium alloy surface, while reducing the coefficient of friction, thus greatly improving its service reliability under friction and wear conditions.

[0030] 3. This invention has excellent antioxidant capacity, which can effectively block the diffusion of oxygen atoms at high temperatures. Combined with a thermal expansion coefficient similar to that of the matrix, it significantly reduces the impact of thermal stress, thereby extending the service life of titanium alloy components in medium and high temperature environments.

[0031] 4. The process of this invention relies only on a conventional vacuum furnace, without the need for expensive special equipment. The operation steps are simple and the parameters are easy to control. It is applicable to various complex titanium alloy components, has good versatility and scalability, significantly reduces production costs and achieves green and environmentally friendly production.

[0032] 5. Overall, this invention breaks through the bottleneck of existing surface modification technology, providing reliable technical support for the widespread application of titanium alloys in high-end fields such as aerospace, energy and chemical industry, and has significant economic and social benefits. Attached Figure Description

[0033] Figure 1 The microstructure of the TC4 titanium alloy surface layer in Example 1 of this invention is shown.

[0034] Figure 2 The images show the TEM microstructure, compositional morphology, and high-resolution images of the TC4 titanium alloy surface layer in Example 1 of this invention.

[0035] Figure 3 This is a SEM image of the surface cross-section of the TC6 titanium alloy in Example 2 of the present invention, showing its morphology and composition.

[0036] Figure 4 The images show the cross-sectional scanning electron microscope (SEM) morphology of TC4 titanium alloy in Examples 4(a), 5(b), Comparative Example 1(c), and Comparative Example 2(d) of this invention.

[0037] Figure 5The images show cross-sectional scanning electron microscope (SEM) images of the TC6 titanium alloy in Example 6(a) and the TA2 titanium alloy in Example 7(b) of this invention.

[0038] Figure 6 The image shows the SEM morphology of the TC4 titanium alloy cross section in Comparative Example 3.

[0039] Figure 7 This is an X-ray diffraction pattern of the surface of TC4 titanium alloy containing a high-temperature anti-oxidation and wear-resistant strengthening layer of titanium carbide modified by the technology of the present invention in Example 4 of the present invention.

[0040] Figure 8 This shows the thickness test of the titanium carbide coating in Example 4 of the present invention.

[0041] Figure 9 This shows the friction coefficient test of the TC4 titanium alloy surface in Example 4 of the present invention.

[0042] Figure 10 This shows the nanoindentation test on the surface of TC4 titanium alloy in Example 4 of the present invention.

[0043] Figure 11 This shows the scratch test on the surface of TC4 titanium alloy in Example 4 of the present invention.

[0044] Figure 12 The high-temperature oxidation resistance test of the TC4 titanium alloy surface in Example 4 of the present invention is shown. (a) TC4 titanium alloy after coating and vacuum heat treatment according to the present invention in Example 4; (b) original TC4 titanium alloy without the treatment of the present invention; (c) TC4 titanium alloy with surface modification in Figure a after heat treatment in air at 800 °C; (d) original TC4 titanium alloy without the treatment of the present invention after heat treatment in air at 800 °C.

[0045] Figure 13 The microhardness (HRC) test of the TC6 titanium alloy cross section in Example 6 of the present invention is shown. Detailed Implementation

[0046] The technical solution of the present invention will be further explained and described below with reference to specific embodiments and accompanying drawings.

[0047] Example 1

[0048] The organic composite binder containing nanodiamonds in this embodiment comprises, by weight percentage: 15% nanodiamond powder with an average particle size of 500 nm, 50% 3-methoxy-3-methylbutanol, 5% silane coupling agent KH560, 5% Cr powder with an average particle size of 2 μm, 2% B powder with an average particle size of 2 μm, 5% Al powder with an average particle size of 2 μm, 3% Ni powder with an average particle size of 2 μm, and 15% polyvinyl alcohol.

[0049] The preparation method of the organic composite binder containing nanodiamonds is as follows: First, the above-mentioned 3-methoxy-3-methylbutanol, silane coupling agent KH560 and polyvinyl alcohol are stirred evenly to a transparent solution. Then, Cr powder, B powder, Al powder and Ni powder are added sequentially at a speed of 500 rpm using a dispersing mixer. The speed is increased to 1400 rpm and the mixture is stirred rapidly for 30 min. Then, the speed is reduced to 500 rpm and nanodiamond powder is slowly added. After the nanodiamond powder is completely added, the speed is increased to 1400 rpm and the mixture is stirred rapidly for 30 min to obtain the final product.

[0050] An organic composite adhesive containing nanodiamonds was uniformly brushed onto the surface of TC4 titanium alloy, then dried and cured at 100 °C for 20 min. The cured TC4 titanium alloy was then placed in a vacuum furnace and evacuated to a vacuum level of 7 × 10⁻⁶. -3 Under vacuum, the temperature is increased to 800 ℃ at a heating rate of 20 ℃ / min and held for 0.5 h. Then, the temperature is increased to 1000 ℃ at a heating rate of 20 ℃ / min and held for 0.5 h. Finally, the temperature is cooled in the furnace to obtain a high-temperature anti-oxidation and wear-resistant strengthening layer of titanium carbide on the surface of TC4 titanium alloy in situ.

[0051] Example 2

[0052] The organic composite binder containing nanodiamonds in this embodiment comprises, by weight percentage: 50% nanodiamond powder with an average particle size of 100 nm, 15% N,N-dimethylacetamide, 5% silane coupling agent KH560, 5% Cr powder with an average particle size of 500 nm, 2% B powder with an average particle size of 500 nm, 5% Al powder with an average particle size of 500 nm, 3% Ni powder with an average particle size of 500 nm, and 15% polyvinylpyrrolidone.

[0053] The preparation method of the organic composite binder containing nanodiamonds is as follows: First, N,N-dimethylacetamide, silane coupling agent KH560, and polyvinylpyrrolidone are stirred evenly to form a transparent solution. Then, Cr powder, B powder, Al powder, and Ni powder are added sequentially at a speed of 300 rpm using a dispersing mixer. The speed is increased to 1000 rpm and the mixture is stirred rapidly for 1 h. Then, the speed is reduced to 300 rpm and nanodiamond powder is slowly added. After the nanodiamond powder has been completely added, the speed is increased to 1000 rpm and the mixture is stirred rapidly for 2 h to obtain the final product.

[0054] An organic composite binder containing nanodiamonds was uniformly brushed onto the surface of TC6 titanium alloy, then dried and cured at 150 °C for 5 min. The cured TC6 titanium alloy was then placed in a vacuum furnace and evacuated to a vacuum level of 5 × 10⁻⁶.-3 Pa, maintain vacuum, heat to 700 ℃ at a heating rate of 10 ℃ / min and hold for 5 h, then heat to 900 ℃ at a heating rate of 10 ℃ / min and hold for 5 h, finally cool with the furnace to obtain a high-temperature anti-oxidation and wear-resistant strengthening layer of titanium carbide on the surface of TC6 titanium alloy in situ.

[0055] Example 3

[0056] The organic composite binder containing nanodiamonds in this embodiment comprises, by weight percentage: 25% nanodiamond powder with an average particle size of 250 nm, 50% N,N-dimethylacetamide, 1% silane coupling agent KH560, 9% Cr powder with an average particle size of 1 μm, and 15% polyvinylpyrrolidone.

[0057] The preparation method of the organic composite binder containing nanodiamonds is as follows: First, N,N-dimethylacetamide, silane coupling agent KH560, and polyvinylpyrrolidone are stirred evenly to form a transparent solution. Then, Cr powder is added using a dispersing mixer at a speed of 400 rpm. The speed is increased to 1200 rpm and stirred rapidly for 1 hour. Then, the speed is reduced to 400 rpm and nanodiamond powder is slowly added. After the nanodiamond powder is completely added, the speed is increased to 1200 rpm and stirred rapidly for 1 hour to obtain the final product.

[0058] An organic composite binder containing nanodiamonds was uniformly brushed onto the surface of TC4 titanium alloy, then dried and cured at 100 °C for 10 min. The cured TC4 titanium alloy was then placed in a vacuum furnace and evacuated to a vacuum level of 4 × 10⁻⁶. -3 Pa, maintain vacuum, heat to 750 ℃ ​​at a heating rate of 15 ℃ / min and hold for 2 h, then heat to 950 ℃ at a heating rate of 15 ℃ / min and hold for 2 h, finally cool with the furnace to obtain a high-temperature anti-oxidation and wear-resistant strengthening layer of titanium carbide on the surface of TC4 titanium alloy in situ.

[0059] Example 4

[0060] The organic composite binder containing nanodiamonds in this embodiment comprises, by weight percentage: 30% nanodiamond powder with an average particle size of 250 nm, 50% N,N-dimethylacetamide, 2% silane coupling agent KH560, 2% Cr powder with an average particle size of 1 μm, 1% B powder with an average particle size of 1 μm, and 15% polyvinylpyrrolidone.

[0061] The preparation method of the organic composite binder containing nanodiamonds is as follows: First, N,N-dimethylacetamide, silane coupling agent KH560, and polyvinylpyrrolidone are stirred evenly to form a transparent solution. Then, Cr powder and B powder are added using a dispersing mixer at a speed of 400 rpm. The speed is increased to 1200 rpm and stirred rapidly for 1 h. Then, the speed is reduced to 400 rpm and nanodiamond powder is slowly added. After the nanodiamond powder is completely added, the speed is increased to 1200 rpm and stirred rapidly for 1 h to obtain the final product.

[0062] An organic composite binder containing nanodiamonds was uniformly brushed onto the surface of TC4 titanium alloy, then dried and cured at 150 °C for 10 min. The cured TC4 titanium alloy was then placed in a vacuum furnace and evacuated to a vacuum level of 5 × 10⁻⁶. -3 Pa, maintain vacuum, heat to 750 ℃ ​​at a heating rate of 15 ℃ / min and hold for 1 h, then heat to 950 ℃ at a heating rate of 15 ℃ / min and hold for 2 h, and finally cool with the furnace to obtain a high-temperature anti-oxidation and wear-resistant strengthening layer of titanium carbide on the surface of TC4 titanium alloy in situ.

[0063] Example 5

[0064] The organic composite binder containing nanodiamonds in this embodiment comprises, by weight percentage: 30% nanodiamond powder with an average particle size of 250 nm, 50% N,N-dimethylacetamide, 2% silane coupling agent KH560, 2% Cr powder with an average particle size of 1 μm, 1% B powder with an average particle size of 1 μm, and 15% polyvinylpyrrolidone.

[0065] The preparation method of the organic composite binder containing nanodiamonds is as follows: First, N,N-dimethylacetamide, silane coupling agent KH560, and polyvinylpyrrolidone are stirred evenly to form a transparent solution. Then, Cr powder and B powder are added using a dispersing mixer at a speed of 400 rpm. The speed is increased to 1200 rpm and stirred rapidly for 1 h. Then, the speed is reduced to 400 rpm and nanodiamond powder is slowly added. After the nanodiamond powder is completely added, the speed is increased to 1200 rpm and stirred rapidly for 1 h to obtain the final product.

[0066] An organic composite binder containing nanodiamonds was uniformly brushed onto the surface of TC4 titanium alloy, then dried and cured at 150 °C for 10 min. The cured TC4 titanium alloy was then placed in a vacuum furnace and evacuated to a vacuum level of 5 × 10⁻⁶. -3Pa, maintain vacuum, heat to 750 ℃ ​​at a heating rate of 15 ℃ / min and hold for 2 h, then heat to 980 ℃ at a heating rate of 15 ℃ / min and hold for 5 h, finally cool with the furnace to obtain a high-temperature anti-oxidation and wear-resistant strengthening layer of titanium carbide on the surface of TC4 titanium alloy in situ.

[0067] Example 6

[0068] The organic composite binder containing nanodiamonds in this embodiment comprises, by weight percentage: 30% nanodiamond powder with an average particle size of 250 nm, 50% N,N-dimethylacetamide, 2% silane coupling agent KH560, 2% Cr powder with an average particle size of 1 μm, 1% B powder with an average particle size of 1 μm, and 15% polyvinylpyrrolidone.

[0069] The preparation method of the organic composite binder containing nanodiamonds is as follows: First, N,N-dimethylacetamide, silane coupling agent KH560, and polyvinylpyrrolidone are stirred evenly to form a transparent solution. Then, Cr powder and B powder are added using a dispersing mixer at a speed of 400 rpm. The speed is increased to 1200 rpm and stirred rapidly for 1 h. Then, the speed is reduced to 400 rpm and nanodiamond powder is slowly added. After the nanodiamond powder is completely added, the speed is increased to 1200 rpm and stirred rapidly for 1 h to obtain the final product.

[0070] An organic composite binder containing nanodiamonds was uniformly brushed onto the surface of TC6 titanium alloy, then dried and cured at 150 °C for 10 min. The cured TC6 titanium alloy was then placed in a vacuum furnace and evacuated to a vacuum level of 5 × 10⁻⁶. -3 Pa, maintain vacuum, heat to 750 ℃ ​​at a heating rate of 15 ℃ / min and hold for 1 h, then heat to 950 ℃ at a heating rate of 15 ℃ / min and hold for 2 h, and finally cool with the furnace to obtain a high-temperature anti-oxidation and wear-resistant strengthening layer of titanium carbide on the surface of TC6 titanium alloy in situ.

[0071] Example 7

[0072] The organic composite binder containing nanodiamonds in this embodiment comprises, by weight percentage: 30% nanodiamond powder with an average particle size of 250 nm, 50% N,N-dimethylacetamide, 2% silane coupling agent KH560, 2% Cr powder with an average particle size of 1 μm, 1% B powder with an average particle size of 1 μm, and 15% polyvinylpyrrolidone.

[0073] The preparation method of the organic composite binder containing nanodiamonds is as follows: First, N,N-dimethylacetamide, silane coupling agent KH560, and polyvinylpyrrolidone are stirred evenly to form a transparent solution. Then, Cr powder and B powder are added using a dispersing mixer at a speed of 400 rpm. The speed is increased to 1200 rpm and stirred rapidly for 1 h. Then, the speed is reduced to 400 rpm and nanodiamond powder is slowly added. After the nanodiamond powder is completely added, the speed is increased to 1200 rpm and stirred rapidly for 1 h to obtain the final product.

[0074] An organic composite adhesive containing nanodiamonds was uniformly brushed onto the surface of TA2 titanium alloy, then dried and cured at 150 °C for 10 min. The cured TA2 titanium alloy was then placed in a vacuum furnace and evacuated to a vacuum level of 5 × 10⁻⁶. -3 Pa, maintain vacuum, heat to 750 ℃ ​​at a heating rate of 15 ℃ / min and hold for 1 h, then heat to 950 ℃ at a heating rate of 15 ℃ / min and hold for 2 h, and finally cool with the furnace to obtain a high-temperature anti-oxidation and wear-resistant strengthening layer of titanium carbide on the surface of TA2 titanium alloy in situ.

[0075] Comparative Example 1

[0076] The organic composite adhesive containing nanodiamonds from Example 4 was uniformly brushed onto the surface of TC4 titanium alloy, then dried and cured at 150 °C for 10 min. The dried and cured TC4 titanium alloy was then placed in a vacuum furnace and evacuated to a vacuum level of 5 × 10⁻⁶. -3 Pa, maintain vacuum, heat to 450 ℃ at a heating rate of 15 ℃ / min and hold for 1 h, then heat to 820 ℃ at a heating rate of 15 ℃ / min and hold for 2 h, and finally cool with the furnace.

[0077] The difference between Comparative Example 1 and Example 4 is that the subsequent vacuum heat treatment temperature of the TC4 titanium alloy after drying and curing is different. In Example 4, the vacuum heat treatment temperature is 750 ℃ ​​for 1 h and then 950 ℃ for 2 h, while in Comparative Example 1, the vacuum heat treatment temperature is 450 ℃ for 1 h and then 820 ℃ for 2 h.

[0078] Comparative Example 2

[0079] The organic composite adhesive containing nanodiamonds from Example 4 was uniformly brushed onto the surface of TC4 titanium alloy, then dried and cured at 150 °C for 10 min. The dried and cured TC4 titanium alloy was then placed in a vacuum furnace and evacuated to a vacuum level of 5 × 10⁻⁶. -3Pa, maintain vacuum, heat to 450 ℃ at a heating rate of 15 ℃ / min and hold for 1 h, then heat to 1050 ℃ at a heating rate of 15 ℃ / min and hold for 2 h, and finally cool with the furnace.

[0080] The difference between Comparative Example 2 and Example 4 is that the subsequent vacuum heat treatment temperature of the TC4 titanium alloy after drying and curing is different. In Example 4, the vacuum heat treatment temperature is 750 ℃ ​​for 1 h and then 950 ℃ for 2 h, while in Comparative Example 1, the vacuum heat treatment temperature is 450 ℃ for 1 h and then 1050 ℃ for 2 h.

[0081] Comparative Example 3

[0082] All the penetration enhancers in Example 1 were removed, the content of 3-methoxy-3-methylbutanol was changed to 65%, the content of nanodiamond and other components remained unchanged, and the process and parameters were kept the same as in Example 1.

[0083] The difference between Comparative Example 3 and Example 1 is that there was no penetration enhancer in Comparative Example 1, the content of nanodiamond and other components, as well as the process and parameters remained unchanged.

[0084] This invention provides a technique for in-situ generation of a high-temperature oxidation-resistant and wear-resistant titanium carbide layer on the surface of a titanium alloy substrate using nanodiamond as a carbon source. This technique can form a dense and uniform high-temperature oxidation-resistant and wear-resistant titanium carbide layer with adjustable thickness on the surface of various titanium alloys through an extremely simple process (coating, vacuum heat treatment), which significantly improves the surface hardness, wear resistance and high-temperature oxidation resistance of titanium alloys.

[0085] Figure 1 This shows the microstructure of the TC4 titanium alloy surface layer in Example 1. From... Figure 1 It can be observed that a TiC reinforcement layer with a thickness of approximately 1-2 μm was formed on the surface of the TC4 titanium alloy modified in Example 1. Simultaneously, numerous needle-like TiB2 compounds were formed between the substrate and the TiC layer. These needle-like TiB2 compounds, anchored within the substrate, significantly improved the adhesion between the TiC reinforcement layer and the substrate. Furthermore, many Cr-rich particulate compounds were observed within the substrate, primarily due to the significant catalytic effect of Cr on nanodiamonds. Figure 2 This can promote the amorphization of the nanodiamond surface and allow it to penetrate rapidly into the substrate, significantly refining the grain structure of the substrate surface. Figure 12 ).

[0086] Figure 2The images show the TEM microstructure, compositional morphology, and high-resolution image of the TC4 titanium alloy surface layer in Example 1. The images show that the surface of the diamond particles (upper left: bright field phase of the diamond particles; upper right: compositional surface scan of C) becomes amorphous under the influence of Cr, forming an amorphous layer (FFT2 region in the lower right image). Furthermore, fine Cr-rich particles are observed within the diamond particles (lower left: compositional surface scan of Cr), confirming the effect of Cr on the diamond particles.

[0087] Figure 3 The images show the SEM morphology and compositional plane scan of the TC6 titanium alloy surface section in Example 2. The images show that Ni has a deep and relatively uniform diffusion (lower left image), while B is mainly concentrated in the outermost layer (lower right image). Al and Ti are also mainly found in the outermost layer. Furthermore, the matrix itself contains a large amount of Ti and Al.

[0088] Figure 4 The images show cross-sectional scanning electron microscope (SEM) images of the TC4 titanium alloys in Examples 4(a), 5(b), Comparative Example 1(c), and Comparative Example 2(d). Figure 1 It can be observed that in this invention, the thickness of the high-temperature anti-oxidation and wear-resistant strengthening layer of titanium carbide can be adjusted by adjusting the vacuum heat treatment temperature (Figures a and b), and the coating thickness can reach about 10 μm. When the vacuum heat treatment temperature is reduced (Figure c), the titanium carbide coating is not dense and uneven, and the coating is relatively thin. When the vacuum heat treatment temperature is increased (Figure d), many defects have appeared between the high-temperature anti-oxidation and wear-resistant strengthening layer of titanium carbide and the substrate, and the bonding force has decreased significantly.

[0089] Figure 5 The images show cross-sectional scanning electron microscope (SEM) morphology images of the TC6 titanium alloy in Example 6(a) and the TA2 titanium alloy in Example 7(b). (The images were obtained through...) Figure 2 It can be seen that the technology provided by the present invention, which uses nanodiamond as a carbon source to generate a high-temperature oxidation-resistant and wear-resistant titanium carbide strengthening layer on the surface of the titanium alloy matrix in situ, can be applied to a variety of titanium alloys, indicating that the technology of the present invention has versatility and scalability in titanium alloys.

[0090] Figure 6 The image shows the SEM morphology of the TC4 titanium alloy cross-section in Comparative Example 3. Compared with Example 1, it is difficult to form a continuous, uniform TiC reinforcement layer with a certain depth on the titanium alloy surface due to the lack of synergistic co-diffusion effect of the infiltration aid.

[0091] Figure 7The image shows an X-ray diffraction pattern of the TC4 titanium alloy surface modified with the technology of this invention in Example 4, which contains a high-temperature oxidation-resistant and wear-resistant titanium carbide reinforcing layer. As can be seen from the image, the surface composition of the modified TC4 titanium alloy is mainly αTi from the matrix, and titanium carbide formed on the TC4 alloy surface using this invention. This indicates that the high-temperature oxidation-resistant and wear-resistant titanium carbide reinforcing layer is formed in situ on the TC4 titanium alloy surface using this invention.

[0092] Figure 8 The thickness of the titanium carbide coating in Example 4 was tested, and the thickness of the high-temperature oxidation-resistant and wear-resistant reinforced titanium carbide layer was 4.25 μm.

[0093] Figure 9 The friction coefficient of the TC4 titanium alloy surface in Example 4 was tested. The technology of this invention can significantly improve the wear resistance of TC4 titanium alloy. The friction coefficient of the original TC4 titanium alloy is generally about 0.4-0.5, while the friction coefficient of the TC4 titanium alloy improved by this invention is reduced to 0.2.

[0094] Figure 10 This is a nanoindentation test on the surface of the TC4 titanium alloy in Example 4. The technology of this invention can significantly improve the surface hardness of the TC4 titanium alloy. The original TC4 titanium alloy has a surface nanohardness of approximately 4.5 GPa and an elastic modulus of approximately 167 GPa. The TC4 titanium alloy improved by the technology of this invention has a surface nanohardness of 11.3 GPa and an elastic modulus of 237 GPa.

[0095] Figure 11 This is a scratch test of the TC4 titanium alloy surface in Example 4. The in-situ generated high-temperature oxidation-resistant and wear-resistant reinforced titanium carbide layer of this invention has excellent metallurgical bonding with the substrate. Its peel force in the scratch test is 29.5 N, corresponding to a bonding strength of approximately 77 MPa.

[0096] Figure 12 This is a high-temperature oxidation resistance test of the TC4 titanium alloy surface in Example 4. (The text appears to be incomplete and contains several grammatical errors. A more accurate translation would require the full context.) Figure 7 It can be observed that after heat treatment at 800 ℃ in air atmosphere for 2 h, the macroscopic morphology of the TC4 titanium alloy treated by the technology of this invention remains intact compared with the original titanium alloy without treatment, indicating that its high-temperature oxidation resistance has been significantly improved.

[0097] Figure 13 The microhardness (HRC) of the TC6 titanium alloy cross-section in Example 6 was measured. Figure 8 It can be observed that the TC6 titanium alloy treated by this invention exhibits a grain refinement region of tens of μm near the treated surface, which can significantly improve the surface hardness of the titanium alloy (unlike...). Figure 5 The surface of the high-temperature oxidation-resistant and wear-resistant reinforced layer of titanium carbide tested in the middle Figure 5 The nano-hardness of the high-temperature oxidation-resistant and wear-resistant reinforced layer of titanium carbide. The hardness of the grain-refined region on the surface of the titanium alloy (two test points on the right) is significantly higher than that of the substrate (two test points on the left).

[0098] Through the embodiments of the present invention and the technical results obtained, it can be seen that the present invention's technology of generating a high-temperature anti-oxidation and wear-resistant strengthening layer of titanium carbide on the surface of a titanium alloy substrate in situ using nanodiamond as a carbon source has broken through the surface strengthening technology of various titanium alloys. It can significantly improve the surface hardness, wear resistance and oxidation resistance of various titanium alloys with only a simple process.

[0099] The above description is merely a preferred embodiment of the present invention, and therefore should not be construed as limiting the scope of the present invention. All equivalent changes and modifications made in accordance with the scope of the patent and the contents of the specification should still fall within the scope of the present invention.

Claims

1. A titanium alloy surface titanium carbide high temperature oxidation resistant and strengthening layer, characterized by: The titanium carbide high-temperature oxidation-resistant wear-resistant strengthening layer is in-situ generated on the surface of the titanium alloy substrate with nano diamond as the carbon source under the action of a permeation aid, and mainly consists of titanium carbide, forms a metallurgical bond with the titanium alloy substrate, has a thickness of not more than 10 μm, and is dense and uniform, the permeation aid consists of Cr powder, or consists of Cr powder and at least one of B powder, Al powder and Ni powder; The titanium carbide high-temperature oxidation-resistant wear-resistant strengthening layer is in-situ generated on the surface of the titanium alloy substrate with nano diamond as the carbon source under the action of a permeation aid, and mainly consists of titanium carbide, forms a metallurgical bond with the titanium alloy substrate, has a thickness of not more than 10 μm, and is dense and uniform, the permeation aid consists of Cr powder, or consists of Cr powder and at least one of B powder, Al powder and Ni powder; 2. The titanium alloy surface titanium carbide high-temperature oxidation resistant wear resistant strengthening layer according to claim 1, characterized in that: The titanium alloy substrate is TC4 titanium alloy, TC6 titanium alloy or TA2 titanium alloy.

3. The method of producing a titanium alloy surface titanium carbide high-temperature oxidation-resistant wear-resistant strengthening layer according to claim 1 or 2, characterized in that: The method comprises the following steps: (1) preparing an organic composite binder containing nano diamond, the organic composite binder consisting of 15-50 wt% of nano diamond, 1-5 wt% of a surfactant, 3-15 wt% of a permeation aid, 13-17 wt% of a binder, and an organic solvent as the balance, the permeation aid being Cr powder, or consisting of Cr powder and at least one of B powder, Al powder and Ni powder; (2) coating the organic composite binder containing nano diamond on the surface of the titanium alloy substrate; (3) placing the coated titanium alloy substrate in an oven at 100-150 ℃ for drying and curing treatment for 5-20 min; (4) The dried and solidified titanium alloy base is placed in a vacuum furnace, vacuumed to 1x10 -2 Pa, and kept in a vacuum state, heated to 700-800 ℃, and kept for 0.5-5 h; then heated to 900-1000 ℃ again, and kept for 0.5-5 h, and finally cooled with the furnace, and thus the titanium alloy base is obtained.

4. The production method according to claim 3, characterized by: The particle size of the nano diamond is 100-500 nm.

5. The production method according to claim 3, characterized by: The organic solvent is 3-methoxy-3-methylbutanol or N,N-dimethylacetamide.

6. The production method according to claim 3, wherein: The surfactant is silane coupling agent KH560.

7. The production method according to claim 3, wherein: The permeation aid is at least one of Cr powder with a particle size of 500 nm-2 μm, B powder with a particle size of 500 nm-2 μm, Al powder with a particle size of 500 nm-2 μm and Ni powder with a particle size of 500 nm-2 μm.

8. The production method according to claim 3, wherein: The binder is polyvinyl alcohol or polyvinylpyrrolidone.

9. The production method according to claim 3, wherein: The particle size of the nano diamond is 100-500 nm, the organic solvent is 3-methoxy-3-methylbutanol or N,N-dimethylacetamide, the surfactant is silane coupling agent, the permeation aid is at least one of Cr powder with a particle size of 500 nm-2 μm, B powder with a particle size of 500 nm-2 μm, Al powder with a particle size of 500 nm-2 μm and Ni powder with a particle size of 500 nm-2 μm, and the binder is polyvinyl alcohol or polyvinylpyrrolidone.

10. The production method according to claim 3, wherein: The coating in step (2) is by brushing or dipping.

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