Composite coating for ti al alloy substrate surface and method of making same

Abstract

The application discloses a composite coating for a TiAl alloy substrate surface and a preparation method thereof, and belongs to the technical field of coatings. The composite coating comprises a first adhesion enhancing layer, a first transition layer, a high-temperature wear-resistant layer, a second transition layer, a second adhesion enhancing layer and a wear-resistant lubricating layer which are sequentially attached to the surface of the TiAl alloy substrate. The composite setting of the film layers improves the wear resistance and friction reduction performance of the TiAl alloy substrate.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of coating technology, in particular to a composite coating for the surface of a TiAl alloy substrate and a preparation method thereof. BACKGROUND

[0002] The gamma-TiAl intermetallic compound (hereinafter referred to as TiAl alloy) has high specific strength, specific modulus, good high-temperature fatigue resistance, creep resistance and oxidation corrosion resistance, etc., and is a highly competitive structural material in the field of engines for aerospace, advanced ships, military fighter aircraft, etc. It has been proven that the engine valves made of TiAl alloy not only reduce the weight and prolong the service life, but also reduce fuel consumption and improve engine reliability.

[0003] However, the moving friction parts of the cylinder head valve hole / valve have an extremely harsh working environment, and are long-term exposed to high-temperature and high-pressure environments, and are subjected to high-frequency alternating impact loads. The TiAl alloy substrate has defects such as low hardness and poor wear resistance, which limits the application of TiAl alloy parts under impact wear and high-temperature friction conditions. Therefore, the wear resistance and friction reduction performance of TiAl alloy still need to be improved. SUMMARY

[0004] The main purpose of the present application is to provide a composite coating for the surface of a TiAl alloy substrate and a preparation method thereof, which aims to solve the problem of poor wear resistance and friction reduction performance of the current TiAl alloy.

[0005] To achieve the above-mentioned purpose, the present application provides a composite coating for the surface of a TiAl alloy substrate, which comprises a first adhesion enhancer layer, a first transition layer, a high-temperature wear-resistant layer, a second transition layer, a second adhesion enhancer layer and a wear-resistant lubricating layer attached to the surface of the TiAl alloy substrate in sequence.

[0006] Optionally, the first adhesion enhancer layer is a TiAl layer, and the thickness of the first adhesion enhancer layer is 100-200 nm.

[0007] Optionally, the first transition layer is an N-doped TiAl layer, and the thickness of the first transition layer is 200-300 nm.

[0008] Optionally, the high-temperature wear-resistant layer is a TiAlN layer, and the thickness of the high-temperature wear-resistant layer is 3000-4000 nm.

[0009] Optionally, the second transition layer is an N-doped TiCr layer, and the thickness of the second transition layer is 200-1000 nm.

[0010] Optionally, the second adhesion-enhancing layer is a TiCr layer, and the thickness of the second adhesion-enhancing layer is 200-1000 nm.

[0011] Optionally, the wear-resistant lubricating layer is a silicon-doped diamond layer, and the thickness of the wear-resistant lubricating layer is 1000-4000 nm.

[0012] In addition, to achieve the above-mentioned purpose, the application further provides a preparation method of the composite coating for the surface of a TiAl alloy substrate, for preparing the composite coating for the surface of a TiAl alloy substrate as described above, and the preparation method comprises the following steps:

[0013] The TiAl alloy substrate is placed in a sputtering area, a suitable target material with a purity higher than 99.99% is selected, and high-power pulse magnetron sputtering is sequentially performed on the surface of the TiAl alloy substrate to form a first adhesion-enhancing layer, a first transition layer, a high-temperature wear-resistant layer, a second transition layer, a second adhesion-enhancing layer, and a wear-resistant lubricating layer.

[0014] Optionally, the first transition layer is deposited in an atmosphere of high-purity nitrogen, and the nitrogen flow rate gradually increases during the deposition process; the high-temperature wear-resistant layer is deposited in an atmosphere of high-purity nitrogen, and the nitrogen flow rate is maintained stable during the deposition process; and the second transition layer is deposited in an atmosphere of high-purity nitrogen, and the nitrogen flow rate gradually decreases during the deposition process.

[0015] Optionally, the vacuum chamber has a base vacuum degree less than or equal to 1x10 -3 Pa, and the total deposition time is less than or equal to 1.5 hours.

[0016] The composite coating for the surface of a TiAl alloy substrate and the preparation method thereof provided by the application set multiple functional layers, wherein the first adhesion-enhancing layer enhances the adhesion between the substrate and the composite coating, the first transition layer connects the first adhesion-enhancing layer and the high-temperature wear-resistant layer, so that the high-temperature wear-resistant layer is tightly attached and the risk of falling off is reduced, the high-temperature wear-resistant layer enhances the high-temperature wear-resistant performance of the TiAl alloy substrate, the second transition layer connects the high-temperature wear-resistant layer and the second adhesion-enhancing layer, and the second adhesion-enhancing layer has the same effect as the first adhesion-enhancing layer, i.e., enhancing the adhesion, and the wear-resistant lubricating layer located at the outermost layer is tightly attached to the surface of the substrate, the wear-resistant lubricating layer provides the functions of wear resistance and lubrication with high hardness and low friction coefficient, and the functional layers are combined on the surface of the TiAl alloy substrate, so that the wear resistance and friction reduction performance of the TiAl alloy in a high-temperature environment can be improved, and the service life of the TiAl alloy mechanism parts can be prolonged. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 FIG. 1 is a structural schematic diagram of the composite coating for the surface of a TiAl alloy substrate according to an embodiment of the application.

[0018] Figure 2 This is a cross-sectional morphology diagram of the composite coating prepared in Example 1 of the present invention.

[0019] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0020] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0021] The powertrain is the core system of a vehicle, and its importance is self-evident. With increasing demands for powertrain performance and energy conservation and emission reduction, higher combustion temperatures and detonation pressures place more stringent requirements on the high-temperature strength and wear resistance of key hot-end components (such as high-temperature exhaust valves). Valves made from traditional alloy steel and nickel-based high-temperature alloys face significant challenges in the increasingly demanding operating conditions of high-power-density powertrains due to their high density, insufficient high-temperature strength, and inadequate wear resistance.

[0022] γ-TiAl intermetallic compounds (hereinafter referred to as TiAl alloys) possess high specific strength and specific modulus, as well as excellent resistance to high-temperature fatigue, creep, and oxidation corrosion. They are highly competitive structural materials in the fields of aerospace, advanced ships, and military aircraft engines. Practice has proven that engine valves made of TiAl alloys can not only reduce weight and extend service life, but also reduce fuel consumption and improve engine reliability. However, the working environment of the moving friction components of the cylinder head valve bores / valve is extremely harsh, subjected to high temperature and high pressure for extended periods, and also subjected to high-frequency alternating impact loads. The TiAl alloy matrix has defects such as low hardness and poor wear resistance, which limits the application of TiAl alloy parts under impact wear and high-temperature friction conditions. Therefore, it is necessary to improve the wear resistance and friction reduction properties of TiAl alloys.

[0023] Currently, the technical means commonly used to enhance the wear resistance of titanium alloy surfaces can be divided into the following two categories: the first category is surface modification or strengthening technology, such as carburizing, which is further subdivided into gas carburizing, laser carburizing, plasma carburizing, micro-arc oxidation, etc.; the second category is surface coating technology, such as spraying, vapor deposition, etc.

[0024] Carburizing processes can significantly improve the surface hardness and wear resistance of titanium alloys by forming a carburized layer (with TiC hard phase as the main wear-resistant component). Currently, commonly used carburizing techniques for titanium alloy surfaces include gas carburizing, laser carburizing, and plasma carburizing. However, in gas carburizing, the titanium alloy is completely exposed to the atmosphere. Due to the high affinity between oxygen and titanium, a dense oxide layer easily forms, hindering further diffusion of carbon atoms and limiting the thickness of the carburized layer. Plasma carburizing, with its vacuum processing conditions, avoids the formation of an oxide film and hydrogen embrittlement caused by hydrogen entering the matrix. It also yields a deeper carburized layer with a higher TiC concentration and a shorter carburizing cycle. Its main disadvantages are the need for vacuum equipment and plasma generation devices, resulting in higher costs.

[0025] This invention provides a composite coating for the surface of a TiAl alloy substrate. Figure 1 This is a schematic diagram of the structure of a composite coating used on the surface of a TiAl alloy substrate, as shown below. Figure 1 As shown, the composite coating comprises a first adhesion-enhancing layer 2, a first transition layer 3, a high-temperature wear-resistant layer 4, a second transition layer 5, a second adhesion-enhancing layer 6, and a wear-resistant lubricating layer 7, sequentially attached to the surface of the TiAl alloy substrate 1. The thickness of all the above-mentioned film layers can be controlled within 5 μm.

[0026] The first adhesion enhancement layer 2 can be a TiAl layer with a thickness of 100nm-200nm. The composition of the first adhesion enhancement layer 2 is similar to that of the substrate 1, although there may be slight differences in the ratio of Ti and Al elements. Due to the similar composition, the first adhesion enhancement layer 2 and the substrate 1 have a strong interfacial bond, which can prevent the coating from peeling off and play a supporting role for other outer layers.

[0027] The first transition layer 3 can be an N-doped TiAl layer, denoted as a TiAl(N) layer. Its main structure remains a TiAl alloy, and its thickness is in the range of 200nm-300nm, for example, 200nm, 250nm, or 300nm. Compared to the first adhesion enhancement layer 2, the first transition layer 3 has increased N atom doping in its composition. Besides having a strong interfacial bond with the first adhesion enhancement layer 2, it also connects to the high-temperature wear-resistant layer 4, serving as a compositional transition layer. The N atom doping concentration in the first transition layer 3 can gradually increase outwards along the surface of the substrate 1, forming a concentration gradient and enhancing the adhesion to the high-temperature wear-resistant layer 4.

[0028] The high-temperature wear-resistant layer 4 can be a TiAlN layer with a thickness of 3000nm-4000nm, for example, 3000nm, 3500nm, or 4000nm. The TiAlN coating, with a composition similar to that of the TiAl alloy, exhibits excellent high-temperature wear resistance. The TiAlN coating is a ternary coating developed based on the TiN coating, and it has high compatibility with the TiAl substrate. TiAlN and TiN share the same B1-type NaCl structure, possessing excellent properties such as high hot hardness, good oxidation stability, strong adhesion, and low thermal conductivity. The thickness of the high-temperature wear-resistant layer is relatively large compared to other film layers, allowing it to fully exert its wear-resistant effect under high-temperature environments and providing protection for the TiAl alloy substrate.

[0029] The second transition layer 5 can be an N-doped TiCr layer, denoted as a TiCr(N) layer, with a thickness in the range of 200 nm to 1000 nm, for example, 200 nm, 600 nm, or 1000 nm. The second transition layer 5 has a similar composition to the second adhesion enhancement layer 6, but with increased N atom doping, it connects the high-temperature wear-resistant layer 4 and the second adhesion enhancement layer 6, enhancing the adhesion between them. The N atom doping concentration in the second transition layer 5 can gradually decrease outwards from the surface of the substrate 1, forming a concentration gradient.

[0030] The second adhesion enhancement layer 6 can be a TiCr layer with a thickness in the range of 200nm-1000nm, for example, 200nm, 600nm or 1000nm. The second adhesion enhancement layer 6 forms a strong interfacial bond with the wear-resistant lubricating layer, tightly connecting the outermost wear-resistant lubricating layer 7 in the composite coating, effectively supporting the wear-resistant lubricating layer 7.

[0031] The wear-resistant lubricating layer 7 can be a silicon-doped diamond-like carbon (DLC) layer with a thickness ranging from 1000 nm to 4000 nm, for example, 1000 nm, 2500 nm, or 4000 nm. TiAlN coatings, as nitride coatings, have a relatively high coefficient of friction and are slightly weaker in lubrication compared to carbon films. There are many types of carbon film coatings, with DLC coatings being the most typical example. DLC coatings are excellent candidates for wear-resistant lubricating coatings due to their high hardness and low coefficient of friction. DLC coatings combine the properties of diamond (Si)... 3 ) structure and graphite (sp 2 Amorphous carbon films with a structure of ) can be controlled by adjusting sp 3 / sp 2By adjusting ratios, coating microstructure, and doping methods, the coating hardness (~5GPa to ~80GPa), elastic modulus, and tribological properties under different environments (atmosphere, high humidity, inert gas, high vacuum, water or other media, various atmospheres, etc.) can be controlled within a wide range. This results in coatings with excellent comprehensive properties such as good toughness, controllable hardness and elastic modulus, low coefficient of friction, good wear resistance, good chemical stability, and high film-substrate adhesion strength. Doping DLC ​​coatings with Si can further enhance their high-temperature resistance.

[0032] This invention, based on a DLC coating exhibiting super-lubricating properties, ingeniously proposes a six-layer composite thin-film structure design consisting of an adhesion-enhancing layer, a first transition layer, a high-temperature wear-resistant layer, a second transition layer, a second adhesion-enhancing layer, and a wear-resistant lubricating layer. After applying this coating to TiAl alloy, the average friction coefficient obtained from room-temperature friction experiments using grinding balls of different materials at atmospheric room temperature is significantly reduced. Furthermore, the wear rate of the coating is extremely low (estimated to be below 10%) for the various friction pair materials used. -17 m 3 The coefficient of friction ( / Nm) is superior to most wear rate technical indicators on the market. In particular, when used with Ti6Al4V, it exhibits the lowest and most stable coefficient of friction (among several friction pair materials).

[0033] The composite coating of this invention is doped with Si in the wear-resistant lubricating layer. It is expected to exhibit good wear resistance and friction reduction properties in the temperature range of room temperature to 400-450℃, which can significantly extend the service life of the DLC coating. This provides a design scheme to enhance wear resistance and extend service life for solid lubrication of TiAl alloys under different environments.

[0034] The composite coating of this invention can be used not only for space-based moving mechanisms, but also for ground-based moving parts, as well as in civilian fields such as the automotive industry, processing and manufacturing industry, transportation industry, and shipbuilding industry. It has great application value for reducing friction and energy consumption, improving energy efficiency, and reducing exhaust emissions in civilian industrial moving parts and mechanisms.

[0035] This invention also provides a method for preparing a composite coating on the surface of a TiAl alloy substrate. The method includes: placing the TiAl alloy substrate in a sputtering area, selecting a suitable target material with a purity higher than 99.99%, and sequentially performing high-power pulsed magnetron sputtering on the surface of the TiAl alloy substrate to form a first adhesion enhancement layer, a first transition layer, a high-temperature wear-resistant layer, a second transition layer, a second adhesion enhancement layer, and a wear-resistant lubricating layer.

[0036] All of the above functional layers can be fabricated using HiPIMS (High Power Impulse Magnetron Sputtering) technology, with the background vacuum level in the vacuum chamber during deposition being less than or equal to 1 × 10⁻⁶. -3 The total deposition time was 1.5 hours, and the thickness of each layer was controlled by adjusting the deposition time of each layer. The first adhesion-enhancing layer was prepared using Ti and Al targets. The first transition layer also used Ti and Al targets, and was sputtered in a nitrogen atmosphere with a purity greater than or equal to 99.999%. The high-temperature wear-resistant layer used Ti and Al targets, and was sputtered in a nitrogen atmosphere with a purity greater than or equal to 99.999%. The second transition layer used Ti and Cr targets, and was sputtered in a nitrogen atmosphere with a purity greater than or equal to 99.999%. The second adhesion-enhancing layer used Ti and Cr targets. The wear-resistant lubricating layer used graphite and Si targets.

[0037] The first transition layer, the high-temperature wear-resistant layer, and the second adhesion-enhancing layer can also be prepared using arc plating technology. The wear-resistant lubricating layer can also be prepared using PECVD (Plasma Enhanced Chemical Vapor Deposition) technology.

[0038] In some feasible embodiments, the first transition layer is deposited in a high-purity nitrogen atmosphere, and the nitrogen flow rate gradually increases during the deposition process; the high-temperature wear-resistant layer is deposited in a high-purity nitrogen atmosphere, and the nitrogen flow rate remains stable during the deposition process; the second transition layer is deposited in a high-purity nitrogen atmosphere, and the nitrogen flow rate gradually decreases during the deposition process. The nitrogen flow rate at the end of the deposition of the first transition layer can be the same as the nitrogen flow rate at the beginning of the deposition of the high-temperature wear-resistant layer, and the nitrogen flow rate at the end of the deposition of the high-temperature wear-resistant layer can be the same as the nitrogen flow rate at the beginning of the deposition of the second transition layer.

[0039] The composite coating prepared in this embodiment provides good protection for the TiAl alloy substrate, improves the high-temperature wear resistance and friction reduction performance of the TiAl alloy substrate, thereby extending its service life. Each adhesion enhancement layer and transition layer can enhance the interfacial bonding force between film layers and prevent functional film layers from falling off, while the high-temperature wear-resistant layer and wear-resistant lubrication layer each play their wear-resistant and friction-reducing roles, giving the composite coating good comprehensive performance.

[0040] Example 1

[0041] The composite coating comprises, sequentially attached to a substrate, an adhesion enhancement layer, a first transition layer, a high-temperature wear-resistant layer, a second transition layer, a second adhesion enhancement layer, and a wear-resistant lubricating layer. The substrate is a TiAl alloy, the first adhesion enhancement layer is TiAl, the first transition layer is TiAl(N), the high-temperature wear-resistant layer is TiAlN, the second transition layer is TiCr(N), the second adhesion enhancement layer is TiCr, and the wear-resistant lubricating layer is silicon-doped DLC.

[0042] Each functional layer in the composite coating was prepared using high-power pulsed magnetron sputtering technology: the background vacuum level of the vacuum chamber during the deposition process was less than or equal to 1×10⁻⁶. -3 Pa, total deposition time was 1.5 hours.

[0043] (1) Preparation of the first adhesion enhancement layer: Ti target with a purity of higher than 99.99% and Al target with a purity of higher than 99.99% are used as the target materials. The target power is controlled at 400W-500W and the deposition time is controlled to deposit a first adhesion enhancement layer with a thickness of 200nm on the substrate.

[0044] (2) Preparation of the first transition layer: Ti target with a purity higher than 99.99% and Al target with a purity higher than 99.99% are used as the target material. High-purity nitrogen gas with a purity greater than or equal to 99.999% is used as the reaction gas (the nitrogen gas is gradually increased). The target power is controlled at 400W-500W. The deposition time is controlled and the first transition layer with a thickness of 300nm is deposited.

[0045] (3) Preparation of high temperature wear-resistant layer: Ti target with a purity of higher than 99.99% and Al target with a purity of higher than 99.99% are used as target materials. High-purity nitrogen gas with a purity of greater than or equal to 99.999% (with stable nitrogen flow rate) is used as reaction gas. The target power is controlled at 400-500W. The deposition time is controlled to deposit a high temperature wear-resistant layer with a thickness of 4000nm.

[0046] (4) Preparation of the second transition layer: Ti target with a purity higher than 99.99% and Cr target with a purity higher than 99.99% are used as the target materials. High-purity nitrogen gas with a purity greater than or equal to 99.999% (nitrogen gas gradually decreases) is used as the reaction gas. The target power is controlled at 400W-500W. Other parameters are selected using conventional techniques in this field. The deposition time is controlled to deposit a 1000nm second transition layer 5.

[0047] (5) Preparation of the second adhesion enhancement layer: Ti target with a purity of higher than 99.99% and Cr target with a purity of higher than 99.99% are used as the target materials. The target power is controlled at 400W-500W. The deposition time is controlled and a second adhesion enhancement layer with a thickness of 1000nm is deposited.

[0048] (6) Preparation of wear-resistant lubricating layer: The target material is a graphite target with a purity of more than 99.99% and a Si target with a purity of more than 99.99%. The target power is controlled at 400W-500W. The deposition time is controlled to deposit a wear-resistant lubricating layer with a thickness of 2000nm.

[0049] Figure 2 The image shows the cross-sectional morphology of the composite coating prepared in Example 1. Figure 2 In the diagram, 1-substrate, 2-first adhesion enhancement layer, 3-first transition layer, 4-high temperature wear-resistant layer, 5-second transition layer, 6-second adhesion enhancement layer, 7-wear-resistant lubricating layer, EHT represents the scanning voltage (5.00 kV), Signal A SE2 represents the two-electron mode, WD represents the lens height from the sample surface (8.3 mm), and Mag represents the magnification (5.00 kX). Due to their similar compositions, the first adhesion enhancement layer 2 and the first transition layer 3 do not show a clear boundary, and the second transition layer 5 and the second adhesion enhancement layer 6 show a similar pattern.

[0050] According to the China Academy of Space Technology standard Q / W1106-2007 "Performance Test Method for Sputtered Deposited MoS2 Solid Lubricating Film for Spacecraft", the composite coating surface hardness was 25.25±2.91 GPa, adhesion was greater than or equal to 300 mN, friction coefficient was 0.002, and life was greater than or equal to 1.5×10⁻⁶. 7 The adhesion, abrasion resistance, and lifespan all meet the usage requirements.

[0051] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or system. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or system that includes that element.

[0052] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0053] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural or procedural transformations made based on the description and drawings of the present invention, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

Claims

1. A composite coating for the surface of a TiAl alloy substrate, characterized in that, The composite coating comprises a first adhesion enhancement layer, a first transition layer, a high-temperature wear-resistant layer, a second transition layer, a second adhesion enhancement layer, and a wear-resistant lubricating layer sequentially attached to the surface of a TiAl alloy substrate; the high-temperature wear-resistant layer is a TiAlN layer, and the wear-resistant lubricating layer is a silicon-doped diamond-like layer; the first transition layer is an N-doped TiAl layer, in which the N atom doping concentration gradually increases outward from the substrate surface; the second transition layer is an N-doped TiCr layer, in which the N atom doping concentration gradually decreases outward from the substrate surface.

2. The composite coating for the surface of a TiAl alloy substrate as described in claim 1, characterized in that, The first adhesion enhancement layer is a TiAl layer, and the thickness of the first adhesion enhancement layer is 100nm-200nm.

3. The composite coating for the surface of a TiAl alloy substrate as described in claim 2, characterized in that, The thickness of the first transition layer is 200nm-300nm.

4. The composite coating for the surface of a TiAl alloy substrate as described in claim 3, characterized in that, The thickness of the high-temperature wear-resistant layer is 3000nm-4000nm.

5. The composite coating for the surface of a TiAl alloy substrate as described in claim 4, characterized in that, The thickness of the second transition layer is 200nm-1000nm.

6. The composite coating for the surface of a TiAl alloy substrate as described in claim 5, characterized in that, The second adhesion enhancement layer is a TiCr layer, and the thickness of the second adhesion enhancement layer is 200nm-1000nm.

7. The composite coating for the surface of a TiAl alloy substrate as described in claim 1, characterized in that, The thickness of the wear-resistant lubricating layer is 1000nm-4000nm.

8. A method for preparing a composite coating on the surface of a TiAl alloy substrate, characterized in that, The method for preparing a composite coating for a TiAl alloy substrate as described in any one of claims 1-7 comprises the following steps: The TiAl alloy substrate is placed in the sputtering area, and a suitable target with a purity higher than 99.99% is selected. High-power pulsed magnetron sputtering is performed sequentially on the surface of the TiAl alloy substrate to form a first adhesion enhancement layer, a first transition layer, a high-temperature wear-resistant layer, a second transition layer, a second adhesion enhancement layer, and a wear-resistant lubricating layer.

9. The method for preparing a composite coating on the surface of a TiAl alloy substrate as described in claim 8, characterized in that, The first transition layer is deposited in a high-purity nitrogen atmosphere, and the nitrogen flow rate gradually increases during the deposition process; the high-temperature wear-resistant layer is deposited in a high-purity nitrogen atmosphere, and the nitrogen flow rate remains stable during the deposition process; the second transition layer is deposited in a high-purity nitrogen atmosphere, and the nitrogen flow rate gradually decreases during the deposition process.

10. The method for preparing a composite coating on the surface of a TiAl alloy substrate as described in claim 8 or 9, characterized in that, The background vacuum level in the vacuum chamber during deposition is less than or equal to 1×10⁻⁶. -3 Pa, total deposition time less than or equal to 1.5 hours.

Images