CN115142017A - Is suitable for Ti 3 High-temperature oxidation-resistant TiAl/Cr nano multilayer coating for Al protection and preparation method and application thereof - Google Patents

Abstract

The invention discloses Ti ₃ Ti alloy surface modification technology field ₃ The high-temperature oxidation-resistant TiAl/Cr nano multilayer coating for Al protection comprises a modulation unit consisting of a plurality of alternating metal sublayers, wherein the modulation unit comprises a TiAl sublayer and a Cr sublayer; the scheme adopts a magnetron sputtering technology and adopts a magnetron sputtering method on Ti ₃ TiAl/Cr metal nano multilayer film with excellent high-temperature performance is prepared on Al alloy, wherein a TiAl nano sublayer is formed by the TiAl nano sublayer and Ti ₃ The same chemical components of the Al matrix provide excellent interface compatibility and interface bonding force, the higher aluminum content provides higher high-temperature strength and oxidation resistance, the Cr nano sublayer simultaneously and obviously improves the hardness and toughness of the TiAl nano sublayer, and the Cr nano sublayer alternately existsThe sublayer can induce the formation of a compact two-dimensional nano-layered oxide layer in a high-temperature air environment, and the problem of a loose oxide layer during high-temperature oxidation of a single TiAl coating is solved.

Description

A high-temperature oxidation-resistant TiAl/Cr nano-multilayer coating suitable for Ti3Al protection and Preparation method and application thereof

technical field

The invention relates to the technical field of Ti ₃ Al alloy surface modification, in particular to a high-temperature anti-oxidation TiAl/Cr nano-multilayer coating suitable for Ti ₃ Al protection and a preparation method and application thereof.

Background technique

Ti ₃ Al alloy is an excellent high-temperature structural material in the range of 650-700 ℃ due to its excellent properties such as light weight, high strength, high temperature resistance and high temperature creep resistance, and is widely used in the structural parts of aero-engine compressor discs and blades. , Hypersonic aircraft skin and other fields. Compared with the Ti ₃ Al matrix, the Ti ₃ Al matrix composite reinforced by SiC fiber shows higher high temperature specific strength and specific stiffness, and can further increase the service temperature to above 800 ℃. At this time, the Ti ₃ Al matrix in the composite material will be subjected to more severe environmental erosion, especially in high temperature environment, severe oxidation will occur, due to insufficient aluminum content in the system, resulting in rod-shaped TiO ₂ oxidation at high temperature product, destroying the formation of continuous dense Al ₂ O ₃ layer (usually when the Al content is greater than 59%, it is possible to form a protective continuous Al ₂ O ₃ layer), which also limits the high temperature of SiC fiber reinforced Ti ₃ Al matrix composites. direct application in the field. Therefore, how to solve the serious high temperature oxidation problem of Ti ₃ Al alloy when SiC fiber reinforced Ti ₃ Al matrix composites are in service, and at the same time ensure that the alloy has good mechanical properties at high temperature has become one of the key engineering problems.

At present, surface modification coating technology is one of the effective solutions. Common coating systems include ceramic coatings and metal coatings. Ceramic coatings have high hardness and excellent high temperature resistance, but due to their low elongation and poor compatibility with Ti ₃ Al alloy, which limits its application range as a protective coating on Ti ₃ Al alloy. While another type of metal high-temperature anti-oxidation coating (in which NiCrAlY superalloy coating is a typical representative) has good high-temperature oxidation resistance, but the Ni element in the coating will seriously interact with Ti ₃ Al alloy at high temperature. The interdiffusion of the elements seriously reduces the mechanical properties of the alloy and affects the interfacial bonding ability of the coating and the alloy.

Therefore, the TiAl system with the same chemical composition as the Ti ₃ Al alloy has attracted extensive attention. The TiAl coating system not only satisfies the good compatibility with the alloy, but also has a higher aluminum content than the Ti ₃ Al alloy. Excellent high temperature oxidation resistance. Although a single TiAl coating has good oxidation resistance, there is still a strong competitive relationship between _TiO2 and _{Al2O3 oxidation} products, and its oxidation resistance needs to be further improved. The high brittleness and high temperature oxidation resistance and toughness of TiAl-based coatings will be improved, which will effectively solve the serious oxidation problem of SiC fiber-reinforced Ti ₃ Al-based composites in high temperature environment.

Therefore, there is an urgent need to design a high-temperature oxidation-resistant TiAl/Cr nano-multilayer coating suitable for Ti ₃ Al protection and its preparation method and application.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a high-temperature anti-oxidation TiAl/Cr nano-multilayer coating suitable for Ti ₃ Al protection and its preparation method and application, so as to solve the problems raised in the above background technology.

In order to achieve the above purpose, the present invention provides the following technical solutions: a high-temperature oxidation-resistant TiAl/Cr nano-multilayer coating suitable for Ti ₃ Al protection, comprising a modulation unit composed of several alternate metal sublayers, the The modulation unit includes a TiAl sublayer and a Cr sublayer, and the TiAl sublayer and the Cr sublayer are both metal sublayers.

Further, the above is applicable to the high-temperature anti-oxidation TiAl/Cr nano-multilayer coating for Ti ₃ Al protection, the number of the modulation units>1, and when the number of the modulation units>1, each modulation unit Overlay settings.

Further, the above is applicable to the high-temperature oxidation-resistant TiAl/Cr nano-multilayer coating for Ti ₃ Al protection, and the thickness of the TiAl/Cr nano-multilayer film is 4-5 μm.

Further, in the above-mentioned high-temperature oxidation-resistant TiAl/Cr nano-multilayer coating for Ti ₃ Al protection, the thickness of the TiAl sublayer is 30-60 nm; the thickness of the Cr sub-layer is 1-50 nm.

A preparation method of a high-temperature oxidation-resistant TiAl/Cr nano-multilayer coating suitable for Ti ₃ Al protection, comprising the following steps:

S1: Put the substrate on the sample holder, put it into the coating chamber of the magnetron sputtering device, install the TiAl target and the Cr target on the target position of the sputtering device, and vacuum the chamber;

S2: The substrate is turned on to rotate, and then argon gas is introduced to start magnetron sputtering. After the sputtering is completed, a TiAl/Cr metal nano-multilayer film is obtained on the surface of the substrate.

Further, in the above-mentioned preparation method of a high-temperature anti-oxidative TiAl/Cr nano-multilayer coating suitable for Ti ₃ Al protection, in the above S1, the substrate is cleaned and dried in sequence before use; the cleaning is performed in sequence. Ultrasonic cleaning was performed in acetone and ethanol.

Further, in the above-mentioned preparation method for the high-temperature oxidation-resistant TiAl/Cr nano-multilayer coating for Ti ₃ Al protection, in the above S2, during the sputtering process, the surface of the substrate and the sputtering target are The surfaces are parallel, and the TiAl target and the Cr target are installed on the corresponding target positions of the multi-target magnetron sputtering coating chamber, so that the surfaces of the substrate and the target are parallel.

Further, in the above-mentioned preparation method for the high-temperature oxidation-resistant TiAl/Cr nano-multilayer coating for Ti ₃ Al protection, in the above S2, the sputtering current of the TiAl target is 1-3 A; The sputtering current is 0.1-3A.

Further, in the above-mentioned preparation method of a high-temperature anti-oxidative TiAl/Cr nano-multilayer coating suitable for Ti ₃ Al protection, in the above-mentioned S2, the rotation rate of the substrate is preferably 30-90 r/h.

Compared with the prior art, the beneficial effects of the present invention are:

The present invention includes a TiAl nano-sublayer and a Cr nano-sublayer. The TiAl nano-sublayer provides excellent interfacial compatibility and interfacial bonding force because it has the same chemical composition as the _Ti3Al matrix, while its higher aluminum content provides higher high-temperature strength and oxidation resistance, while the Cr nano-sublayer significantly improves the hardness and toughness of the TiAl nano-sublayer at the same time, and the alternately existing Cr nano-sublayers can induce dense two-dimensional nanolayers in high-temperature air environments. The formation of a quasi-like oxide layer, that is, at high temperature, the Cr nano-sublayer preferentially oxidizes and captures the aluminum element in the lower layer to form a (Cr, Al) ₂ O ₃ ternary dense oxide layer, which realizes the separation of titanium and aluminum elements. and rearrangement, forming a multi-layer dense oxide layer, confining the rod-shaped TiO ₂ into the nano oxide layer, avoiding the formation of a loose oxide layer; It can significantly improve the hardness and toughness of the film as well as the high temperature oxidation resistance.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings used in the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained from these drawings without any creative effort.

1 is a schematic structural diagram of a TiAl/Cr metal nano-multilayer film on an alumina substrate prepared in Example 1 of the present invention;

2 is a schematic diagram of the structure of the TiAl/Cr metal nano-multilayer film on the alumina substrate prepared in Example 2 of the present invention

3 is a schematic diagram of the SEM cross-sectional morphology of the samples prepared in the embodiment of the present invention and the comparative example before and after being oxidized in air at 800° C. for 1 h;

4 is a schematic diagram of the SEM surface morphology of the samples prepared in the embodiment of the present invention and the comparative example before and after being oxidized in air at 800° C. for 1 h;

FIG. 5 is a schematic TEM schematic diagram of the cross-section of Example 2 of the present invention after being oxidized in air at 800° C. for 1 h;

Fig. 6 is embodiment 1 of the present invention, embodiment 2 and comparative example 2 hardness curve graph and indentation SEM figure schematic diagram;

7 is a schematic diagram of the high-temperature oxidation process of the TiAl/Cr metal nano-multilayer coating prepared by the present invention;

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

The invention provides a technical solution: a high-temperature anti-oxidation TiAl/Cr nano-multilayer coating suitable for Ti ₃ Al protection, comprising a modulation unit composed of several metal sub-layers with alternate components, and the modulation unit includes a TiAl sub-layer and Cr sublayer, TiAl sublayer and Cr sublayer are all metal sublayers. The number of modulation units>1, and when the number of modulation units>1, each modulation unit is superimposed and set. The thickness of the TiAl/Cr nano-multilayer film is 4-5 μm; the thickness of the TiAl sub-layer is 30-60 nm; the thickness of the Cr sub-layer is 1-50 nm.

In the present invention, the number of units of the TiAl/Cr metal nano-multilayer film is preferably 70-130, more preferably 80-120, specifically 90 and 100; the TiAl sublayer and Cr in each unit are The thickness ratio of the sublayers is preferably 45:1 to 20, more independently preferably 45:5 to 15, and specifically independently preferably 45:5 and 45:10; in a specific embodiment of the present invention, the thickness of the TiAl sublayer is preferably 45:5 to 15. It is preferably 45 nm, and the thickness of the Cr sublayer is preferably 5 nm and 10 nm.

The TiAl nano-sublayer provides excellent interfacial compatibility and interfacial adhesion due to its same chemical composition as the Ti3Al matrix, while its higher aluminum content provides higher high _- temperature strength and oxidation resistance, while Cr The nano-sublayers also significantly improve the hardness and toughness of TiAl nano-sublayers, and the alternately existing Cr nano-sublayers can induce the formation of dense two-dimensional nano-layered oxide layers under high temperature air environment, that is, at high temperature, Cr nano-layers are formed. While the sub-layer is preferentially oxidized, it preferentially captures the aluminum element in the lower layer to form a (Cr, Al) ₂ O ₃ ternary dense oxide layer, realizes the separation and rearrangement of titanium and aluminum elements, and forms a multi-layer dense oxide layer. The rod-like growth of _TiO2 is confined to the nanoscale oxide layer, avoiding the formation of loose oxide layers.

A preparation method of a high-temperature oxidation-resistant TiAl/Cr nano-multilayer coating suitable for Ti ₃ Al protection, comprising the following steps:

S1: Put the substrate on the sample holder, put it into the coating chamber of the magnetron sputtering device, install the TiAl target and the Cr target on the target position of the sputtering device, and vacuum the chamber; the substrate is used before use Cleaning and drying are carried out successively; cleaning is to carry out ultrasonic cleaning in acetone and ethanol successively (the substrate is placed in acetone, alcohol and deionized water successively for ultrasonic cleaning, and then dried, in the present invention, the substrate is in acetone and no The ultrasonic cleaning time in water ethanol is preferably 15-20min independently, the drying temperature is preferably 40-60°C, and the time is preferably 1-1.5h);

S2: Turn on the substrate to rotate, and then pass argon gas to start magnetron sputtering. After the sputtering is completed, a TiAl/Cr metal nano-multilayer film is obtained on the surface of the substrate; during the sputtering process, the surface of the substrate and the sputtering The surface of the target is parallel, and the TiAl target and the Cr target are installed on the corresponding target positions of the multi-target magnetron sputtering coating chamber, so that the substrate and the target surface are parallel; the sputtering current of the TiAl target is 1-3A,; The sputtering current of the Cr target is 0.1-3 A; the rate of substrate rotation is preferably 30-90 r/h. After the sputtering is completed, the obtained film is cooled to room temperature under vacuum conditions to obtain a TiAl/Cr metal nano-multilayer film. The present invention has no special requirements on the cooling rate, and the coating chamber can be naturally cooled.

In the present invention, argon gas is used as the sputtering gas, the purity of argon gas is preferably 99.995-99.999%, and the flow rate of argon gas is preferably 50-90 sccm, more preferably 60-80 sccm. The invention adopts the magnetron sputtering technology, and uses the TiAl target and the Cr target as the sputtering targets to alternately sputter the Ti3Al substrate to obtain the high _- temperature anti-oxidation nano-multilayer coating. In the present invention, before the sputtering is performed, the vacuum degree of the coating chamber is preferably controlled to be better than 4×10 ^-4 Pa, which can maximize the discharge of gas impurities in the coating chamber and avoid oxidation during the coating process. In the present invention, the surface of the substrate is preferably parallel to the surface of the sputtering target, and it is particularly preferable to install the TiAl target and the Cr target on the corresponding target positions of the multi-target magnetron sputtering coating chamber, so that the substrate and the target are The surface of the material is parallel. In the present invention, the working gas pressure in the sputtering process is preferably 0.5 to 1.2 Pa, more preferably 0.8 Pa. In the present invention, the above-mentioned working air pressure can ensure the best deposition rate. In the present invention, the rotational speed of the substrate holder during the sputtering process is preferably 30-90 r/h, more preferably 60 r/h. In the present invention, the sputtering current of the TiAl target is preferably 1-3A, and the voltage is preferably 300-450V, more preferably 375V; the sputtering current of the Cr target is preferably 0.1-3A, and the voltage is preferably 200-400V, more preferably is 284V; in the present invention, the sputtering time of the high-temperature anti-oxidation nano-multilayer coating is preferably 50-230 min, more preferably 65-125 min.

Comparative Example 1

First, the Ti ₃ Al sheet of φ18*2mm was polished with 1000 mesh, 3000 mesh, 5000 mesh and 7000 mesh sandpaper in sequence on a metal polishing machine until the surface was smooth without obvious scratches. The polished Ti ₃ Al sheet was placed in an acetone solvent, taken out after sonication for 20 min, and finally sonicated with ethanol for 20 min, and dried to obtain a clean Ti ₃ Al substrate.

A high-temperature oxidation experiment was performed on the Ti ₃ Al substrate obtained in this example, that is, the clean Ti ₃ Al substrate was placed in a crucible, placed in a tube furnace, and an alumina heat-insulating plug was placed at the seal, and the method was fastened. blue to seal the port. Then turn on the power of the mechanical pump, adjust the heating program of the tube furnace, and raise the temperature from room temperature to 800 °C at a heating rate of 10 °C/min. During the heating period, the mechanical pump continues to work to avoid excessive oxidation caused by excessive heating time. After holding at 800°C for one hour, the mechanical pump was turned off to simulate the condition of oxidation in air. After the oxidation, the power of the tube furnace was turned off, and the sample was cooled to room temperature with the furnace.

The cross-section and surface SEM observation of the oxidized Ti ₃ Al substrate obtained in this example is carried out. As shown in Fig. 3(a) and Fig. 4(a), the surface of the Ti ₃ Al substrate is covered with a thick oxide layer, about 1.75μm. Numerous ravines and cracks appear on the oxidized surface. This indicates that the Ti ₃ Al substrate undergoes vigorous oxidation at 800 °C.

Comparative Example 2

First, the Ti ₃ Al sheet of φ18*2mm was polished with 1000 mesh, 3000 mesh, 5000 mesh and 7000 mesh sandpaper in sequence on a metal polishing machine until the surface was smooth without obvious scratches. The polished Ti ₃ Al sheet was placed in an acetone solvent, taken out after sonication for 20 min, and finally sonicated with ethanol for 20 min, and dried to obtain a clean Ti ₃ Al substrate; the cleaned substrate was fixed on a rectangular sample holder, Put them into the sample chamber of the multi-target magnetron sputtering equipment; place the TiAl alloy target and the Cr target in the multi-target magnetron sputtering equipment respectively, and adjust the target-to-base distance to 10 cm.

After the preparation is completed, close the vacuum chamber, and evacuate to make the vacuum degree better than 4×10 ^-4 Pa; after the vacuum degree reaches the requirement, open the gas valve, pass in argon, set the gas flow value of argon to 70sccm, adjust The gate valve makes the working pressure in the vacuum coating chamber be 0.8Pa, turn on the DC power switch, and adjust the rotation speed of the substrate holder to 60r/h. Turn on the power of the baffle, and clean the ion source for 20 minutes. After cleaning the ion source, adjust the argon gas flow value back to 70sccm, and adjust the gate valve so that the working pressure in the vacuum coating chamber is 0.8Pa. The current value of the TiAl alloy target was adjusted to 2A, the voltage value was 396V, and the sputtering was performed for 115min. The deposition rate of TiAl alloy target was 45 nm/min. After the deposition, the current of the TiAl alloy target was turned off, the argon gas was stopped, and the gate valve was adjusted to the maximum. When the temperature in the vacuum chamber dropped to room temperature, the sample was taken out and a TiAl monolayer film was obtained on the Ti ₃ Al alloy.

The high temperature oxidation experiment was carried out on the TiAl monolayer film obtained in this example, that is, the TiAl monolayer film _on the Ti3Al sheet (the _Ti3Al sheet with the TiAl monolayer film) was placed in a crucible, and it was placed in a tube furnace , place an alumina heat-insulating plug at the seal, fasten the flange, and seal the port. Then turn on the power of the mechanical pump, adjust the heating program of the tube furnace, and raise the temperature from room temperature to 800 °C at a heating rate of 10 °C/min. During the heating period, the mechanical pump continues to work to avoid excessive oxidation caused by excessive heating time. After holding at 800°C for one hour, the mechanical pump was turned off to simulate the condition of oxidation in air. After the oxidation, the power of the tube furnace was turned off, and the sample was cooled to room temperature with the furnace.

The cross-section and surface SEM observation of the oxidized TiAl monolayer film obtained in this example is carried out. As shown in Figure 3(b) and Figure 4(b), the thickness of the oxide layer is 1.27 μm. Compared with Comparative Example 1, the oxide layer is The thickness is reduced due to the increased Al content which allows the formation of a continuous and dense layer of Al ₂ O ₃ that hinders the further diffusion of oxygen. However, a large number of rod-shaped _TiO2 oxidation products appeared on the surface after oxidation, and the excessive growth of this rod-shaped product would cause pores to provide a channel for the inward diffusion of oxygen. Therefore, the oxidation resistance of this example is improved compared with that of Comparative Example 1, but the oxidation is still relatively severe.

The hardness test and SEM characterization of the TiAl single-layer film obtained in this example were carried out. As shown in (a) in FIG. 6 , the hardness was 8.38 GPa and the modulus was 137 Gpa. From the SEM image of (b) indentation in Figure 6, it is found that relatively obvious cracks begin to appear in this example, and the crack length is 5 μm. This is due to the increased brittleness of the film caused by the higher Al content.

Example 1

First, the Ti ₃ Al sheet of φ18*2mm was polished with 1000 mesh, 3000 mesh, 5000 mesh and 7000 mesh sandpaper in sequence on a metal polishing machine until the surface was smooth without obvious scratches. The polished Ti ₃ Al sheet was placed in an acetone solvent, taken out after sonication for 20 min, and finally sonicated with ethanol for 20 min, and dried to obtain a clean Ti ₃ Al substrate; the cleaned substrate was fixed on a rectangular sample holder, Put them into the sample chamber of the multi-target magnetron sputtering equipment; place the TiAl target and the Cr target in the multi-target magnetron sputtering equipment respectively, and adjust the target-to-base distance to 10 cm.

After the preparation is completed, close the vacuum chamber, and evacuate to make the vacuum degree better than 4×10 ^-4 Pa; after the vacuum degree reaches the requirement, open the gas valve, pass in argon, set the gas flow value of argon to 70sccm, adjust The gate valve makes the working pressure in the vacuum coating chamber be 0.8Pa, turn on the DC power switch, and adjust the rotation speed of the substrate holder to 60r/h. Turn on the power of the baffle, and clean the ion source for 20 minutes. After cleaning the ion source, adjust the argon gas flow value back to 70sccm, and adjust the gate valve so that the working pressure in the vacuum coating chamber is 0.8Pa. The current value of the TiAl target was adjusted to 2A, and the voltage value was 320V; the current value of the Cr target was adjusted to 0.2A, the voltage value was 340V, and the sputtering was performed for 100min. The deposition rate of TiAl target is 45 nm/min, and the deposition rate of Cr target is 5 nm/min. After the deposition is completed, the current of the TiAl alloy target and the Cr target is turned off, the argon gas is stopped, and the gate valve is adjusted to the maximum. When the temperature in the vacuum chamber drops to room temperature, the sample is taken out and deposited alternately on the Ti ₃ Al sheet to obtain modulation. The TiAl/Cr metal nano-multilayer film with a ratio of 45:5 is shown in Figure 1.

A high-temperature oxidation experiment was performed on the TiAl/Cr metal nano-multilayer film with a modulation ratio of 45:5 obtained in this example, that is, a TiAl/Cr metal nano-multilayer film with a modulation ratio of 45:5 on the Ti ₃ Al chip (with a modulation ratio of 45:5). 45:5 TiAl/Cr metal nano-multilayer film (Ti ₃ Al sheet) placed in a crucible, put it into a tube furnace, place an alumina heat-insulating plug at the seal, fasten the flange, and close the port. seal. Then turn on the power of the mechanical pump, adjust the heating program of the tube furnace, and raise the temperature from room temperature to 800 °C at a heating rate of 10 °C/min. During the heating period, the mechanical pump continues to work to avoid excessive oxidation caused by excessive heating time. After holding at 800°C for one hour, the mechanical pump was turned off to simulate the condition of oxidation in air. After the oxidation, the power of the tube furnace was turned off, and the sample was cooled to room temperature with the furnace.

The cross-section and surface SEM observation of the TiAl/Cr metal nano-multilayer film with a modulation ratio of 45:5 obtained in this example is carried out. As shown in (c) in Figure 3 and (c) in Figure 4, the thickness of the oxide layer is 575 nm, The film structure is relatively loose, and the growth of rod-like TiO ₂ on the surface is inhibited. Compared with Comparative Example 2, the thickness of the oxide layer is significantly reduced, indicating that the introduction of the periodic chromium layer makes the nano-multilayer film have better oxidation resistance.

The hardness test and SEM characterization of the TiAl/Cr metal nano-multilayer film with a modulation ratio of 45:5 obtained in this example are carried out. As shown in (a) in Figure 6, the hardness is 9.35GPa; the modulus is 150Gpa . From the indentation SEM image of (c) in FIG. 6 , it is found that the crack in this embodiment is as short as 2 μm.

Example 2

First, the Ti ₃ Al sheet of φ18*2mm was polished with 1000 mesh, 3000 mesh, 5000 mesh and 7000 mesh sandpaper in sequence on a metal polishing machine until the surface was smooth without obvious scratches. At the same time, the polished Ti ₃ Al sheet was placed in acetone solvent, taken out after sonication for 20 min, and finally sonicated with ethanol for 20 min, and dried to obtain a clean Ti ₃ Al substrate; fix the cleaned substrate to a rectangular sample holder Put the TiAl target and the Cr target in the multi-target magnetron sputtering equipment respectively, and adjust the target-to-base distance to 10 cm. After the preparation is completed, close the vacuum chamber, and evacuate to make the vacuum degree better than 4×10 ^-4 Pa; after the vacuum degree reaches the requirement, open the gas valve, pass in argon, set the gas flow value of argon to 70sccm, adjust The gate valve makes the working pressure in the vacuum coating chamber be 0.8Pa, turn on the DC power switch, and adjust the rotation speed of the substrate holder to 60r/h. Turn on the power of the baffle, and clean the ion source for 20 minutes. After cleaning the ion source, adjust the argon gas flow value back to 70sccm, and adjust the gate valve so that the working pressure in the vacuum coating chamber is 0.8Pa. The current value of TiAl alloy target was adjusted to 2A, and the voltage value was 320V; the current value of Cr target was adjusted to 0.4A, the voltage value was 284V, and the sputtering was 77min. The deposition rate of TiAl alloy target is 45 nm/min, and the deposition rate of Cr target is 10 nm/min. After the deposition is completed, the current of the TiAl target and the Cr target is turned off, the argon gas is stopped, and the gate valve is adjusted to the maximum. When the temperature in the vacuum chamber drops to room temperature, the sample is taken out and alternately deposited on the Ti ₃ Al sheet to obtain the modulation ratio. 45:10 TiAl/Cr metal nano-multilayer film.

The high-temperature oxidation experiment was performed on the TiAl/Cr metal nano-multilayer film with a modulation ratio of 45:10 obtained in this example, that is, a TiAl/Cr metal nano-multilayer film with a modulation ratio of 45:10 on a Ti ₃ Al chip (with a modulation ratio of 45:10). 45:10 TiAl/Cr metal nano-multilayer film (Ti ₃ Al sheet) was placed in the crucible, put it into the tube furnace, placed an alumina heat insulation plug at the seal, fastened the flange, and closed the port. seal. Then turn on the power of the mechanical pump, adjust the heating program of the tube furnace, and raise the temperature from room temperature to 800 °C at a heating rate of 10 °C/min. During the heating period, the mechanical pump continues to work to avoid excessive oxidation caused by excessive heating time. After holding at 800°C for one hour, the mechanical pump was turned off to simulate the condition of oxidation in air. After the oxidation, the power of the tube furnace was turned off, and the sample was cooled to room temperature with the furnace.

The cross-section and surface SEM observation of the TiAl/Cr metal nano-multilayer film with a modulation ratio of 45:10 obtained in this example, as shown in Fig. 3(d) and Fig. 4(d), the thickness of the oxide layer is 224 nm, The outer part of the film is relatively loose under the influence of oxygen, but the inner layer of the film is still relatively dense. The rod-like growth of _TiO2 on the oxidized surface almost disappeared, and the surface pores were less, indicating that its oxidation resistance was further improved. Subsequently, cross-sectional TEM observation was performed on the TiAl/Cr metal nano-multilayer film with a modulation ratio of 45:10 obtained in this example, as shown in FIG. 5 . The thickness of the oxide layer is about 300nm, and there is an obvious delamination phenomenon. Under the preferential oxidation of the chromium layer, the Ti and Al elements are separated and rearranged, and the aluminum element preferentially forms (Cr, Al) ₂ O ₃ with the chromium element. meta-dense oxide layer, forming a multi-layer oxide layer barrier, avoiding the appearance of the mixture of _TiO2 and _Al2O3 , confining the rod _- like growth of _TiO2 into the nano-oxide layer, hindering the further inward diffusion of oxygen, to a certain extent Enhanced antioxidant properties.

The hardness test and SEM characterization of the TiAl/Cr metal nano-multilayer film with a modulation ratio of 45:10 obtained in this example were carried out. As shown in (a) in Figure 6, the hardness was 10GPa; the modulus was 165Gpa, Both are better than TiAl monolayer films. From the indentation SEM image of (d) in Figure 6, it is found that almost no cracks can be seen in this example, which indicates that the hardness and toughness of the TiAl/Cr metal nano-multilayer film are improved compared to the TiAl single-layer film.

In the description of this specification, description with reference to the terms "one embodiment," "example," "specific example," etc. means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one aspect of the present invention. in one embodiment or example. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The above-disclosed preferred embodiments of the present invention are provided only to help illustrate the present invention. The preferred embodiments do not exhaust all the details, nor do they limit the invention to only the described embodiments. Obviously, many modifications and variations are possible in light of the content of this specification. The present specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can well understand and utilize the present invention. The present invention is to be limited only by the claims and their full scope and equivalents.

Claims (9)

1. A high-temperature oxidation-resistant TiAl/Cr nano-multilayer coating suitable for Ti ₃ Al protection, comprising a modulation unit composed of several alternate metal sublayers, characterized in that: the modulation unit comprises a TiAl sublayer and a Cr sublayer, the TiAl sublayer and the Cr sublayer are both metal sublayers. 2 . The high-temperature anti-oxidative TiAl/Cr nano-multilayer coating for Ti ₃ Al protection according to claim 1 , wherein: the number of the modulation units is >1, and when the modulation units When the number of modulation units is greater than 1, each modulation unit is superimposed and set. 3 . The high-temperature oxidation-resistant TiAl/Cr nano-multilayer coating for Ti ₃ Al protection according to claim 1 , wherein the thickness of the TiAl/Cr nano-multilayer film is 4-5 μm. 4 . 4 . The high-temperature oxidation-resistant TiAl/Cr nano-multilayer coating for Ti ₃ Al protection according to claim 1 , wherein the thickness of the TiAl sub-layer is 30-60 nm; the Cr sub-layer has a thickness of 30-60 nm; The thickness is 1 to 50 nm. 5. a kind of preparation method suitable for Ti3Al protection with high temperature anti _- oxidation TiAl/Cr nano-multilayer coating according to claim 1, is characterized in that, comprises the following steps: S1: Put the substrate on the sample holder, put it into the coating chamber of the magnetron sputtering device, install the TiAl target and the Cr target on the target position of the sputtering device, and vacuum the chamber; S2: The substrate is turned on to rotate, and then argon gas is introduced to start magnetron sputtering. After the sputtering is completed, a TiAl/Cr metal nano-multilayer film is obtained on the surface of the substrate. 6 . The method for preparing a high-temperature anti-oxidative TiAl/Cr nano-multilayer coating for Ti ₃ Al protection according to claim 5 , wherein in the above-mentioned S1, the substrates are sequentially used before use. 7 . Carry out cleaning and drying; the cleaning is ultrasonic cleaning in acetone and ethanol in sequence. 7 . The method for preparing a high-temperature anti-oxidative TiAl/Cr nano-multilayer coating for Ti ₃ Al protection according to claim 5 , wherein in the above-mentioned S2 , in the sputtering process, The surface of the substrate is parallel to the surface of the sputtering target, and the TiAl target and the Cr target are installed on the corresponding target positions of the multi-target magnetron sputtering coating chamber, so that the surfaces of the substrate and the target are parallel. 8 . The method for preparing a high-temperature anti-oxidative TiAl/Cr nano-multilayer coating for Ti ₃ Al protection according to claim 5 , wherein in the above S2 , the sputtering current of the TiAl target 1-3A,; the sputtering current of the Cr target is 0.1-3A. 9. a kind of preparation method suitable for high temperature oxidation-resistant TiAl/Cr nano-multilayer coating for Ti ₃ Al protection according to claim 5, is characterized in that: in above-mentioned S2, the speed of described substrate rotation is It is preferably 30 to 90 r/h.

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