CN116445854A - Superlattice tough high-entropy alloy nitride ceramic coating and preparation method thereof - Google Patents

Abstract

A superlattice tough high-entropy alloy nitride ceramic coating and a preparation method thereof are characterized in that the coating is formed by alternately arranging two high-entropy alloy nitride ceramics with face-centered cubic (fcc) structures in a nano-scale thickness. The hardness of the superlattice high-entropy alloy nitride ceramic coating obtained after annealing at 750 ℃ for one hour is more than 40GPa, the requirement of superhard material is met, and the fracture toughness exceeds 5MPa m ^1/2 The effect of simultaneously hardening and toughening the high-entropy nitride ceramic film is realized. The superlattice tough high-entropy alloy nitride ceramic coating provided by the invention is processed in advanceHas wide application prospect in the fields of tools, aerospace equipment and the like.

Description

A superlattice tough high-entropy alloy nitride ceramic coating and its preparation method

technical field

The invention relates to the technical field of material surface coatings, in particular to a ceramic coating technology, in particular to a superlattice tough high-entropy alloy nitride ceramic coating and its preparation method and application.

Background technique

Traditional transition metal nitride ceramics, such as TiN, TiAlN and CrAlN, have excellent mechanical properties such as high hardness, high elastic modulus and high wear resistance, as well as high temperature stability such as high melting point and ablation resistance. , Die and other machinery manufacturing and aviation, aerospace, nuclear energy and other high-end equipment fields are widely used. High hardness is obviously a highly sought-after characteristic in machine building, as it prevents the tool from wearing out under extreme working pressures to prolong its life and improve machining performance. Typically, hardness enhancement is achieved by confining dislocations and slip, reducing plastic deformation in the material, however, this leads to embrittlement of the material and a significant reduction in damage tolerance. Therefore, in order to improve the durability of coated tools, it is necessary to design coating materials with strong and tough properties.

Since 2004, the emergence of high-entropy alloys broke through the traditional concept of material design and greatly expanded the composition space. With the high-entropy oxide (MgNiCoCuZn)O first reported by Rost et al., the concept of "high-entropy" was introduced into ceramics and stimulated research interest in high-entropy ceramics. High-entropy ceramics are solid solutions based on interstitial phases, containing 4 or more metal elements, due to entropy stability endow high-entropy nitrides with unique physical and mechanical properties, making them stable in hardness, fracture toughness, corrosion resistance and high temperature In terms of performance, it surpasses the traditional nitride ceramics, so high ceramics have attracted more and more attention.

In order to develop high-entropy nitride ceramic coatings with suitable mechanical and physical properties, scholars have adjusted the chemical composition of materials and optimized coating growth parameters through element design and preparation process optimization to control stoichiometry, microstructure and texture. Improve coating performance. In addition, scholars have also proposed many strategies from the perspective of coating structure to increase the ability of ceramic films to inhibit crack propagation. Superlattice structure is an effective toughening method, and the hardness and fracture toughness of transition metal nitrides have been greatly improved by the alternate deposition of chemically different but structurally coherent nanolayers.

Contents of the invention

The purpose of the present invention is to solve the problem that the existing high-entropy alloy nitride ceramic coating toughness and hardness are mutually restricted, to invent a superlattice tough high-entropy alloy nitride ceramic coating, and to provide a corresponding preparation method at the same time.

One of technical solutions of the present invention is:

A superlattice tough high-entropy alloy nitride ceramic coating is characterized in that the superlattice structure is composed of two kinds of face-centered cubic (fcc) structure high-entropy alloy nitride ceramics deposited alternately with nanoscale thickness.

2. superlattice tough high-entropy alloy nitride ceramic coating according to claim 1, is characterized in that, two kinds of face-centered cubic structure high-entropy alloy nitrides are arbitrary two in TiZrNbMoHfN, TiZrNbMoTaN, TiZrNbMoWN and TiZrHfNbTaN The combination.

3. superlattice tough high-entropy alloy nitride ceramic coating according to claim 1, is characterized in that, the thickness of superlattice structure modulation period is 2～25nm of each layer of nitride, gained superlattice The hardness of the high-entropy alloy nitride ceramic coating is greater than 40GPa, which meets the requirements of superhard materials, and the fracture toughness exceeds 5MPa·m ^1/2 , realizing the effect of increasing the hardness and toughening of the high-entropy nitride ceramic film.

The second technical scheme of the present invention is:

A method for preparing a superlattice tough high-entropy alloy nitride ceramic coating is characterized in that it comprises the following steps:

Step 1, place the substrate in the vacuum chamber, feed high-purity argon gas, control the vacuum chamber pressure to 0.33~0.8Pa, control the pulse bias voltage to -800~-600V, and argon glow discharge to generate plasma on the substrate surface Perform activation cleaning;

Step 2, depositing a Ti transition layer with a thickness of 200-500nm by magnetron sputtering on the surface of the substrate, the gas source of the transition layer magnetron sputtering is argon, and the pressure of the magnetron sputtering chamber is 0.4-0.8Pa; the magnetron sputtering The cathode target material is the metal target material of Ti single substance;

Step 3, high-entropy nitride ceramic coating is deposited by radio-frequency reactive magnetron sputtering on the surface of the alloy transition layer, the gas source of radio-frequency reactive magnetron sputtering is argon and nitrogen, and the flow ratio of nitrogen and argon is (0.25~1 ): 1, the working pressure of the reactive magnetron sputtering chamber is 0.4-0.8Pa; the cathode target of RF reactive magnetron sputtering is TiZrNbMoHf, TiZrNbMoTa, TiZrNbMoW or TiZrHfNbTa in the high-entropy alloy target; the bias voltage applied to the sample The temperature is -70~-200V; the deposition temperature is 350~450°C; the double-layer periodic superlattice structure is realized by opening and closing the computer-controlled baffle above the alloy target of TiZrNbMoHf-TiZrNbMoTa or TiZrNbMoW-TiZrHfNbTa combination.

After the coating is prepared, annealing is carried out under the protection of argon to improve or eliminate the structural defects and residual stress generated during the coating preparation process, and prevent the coating from cracking and peeling, including the following steps:

Step 1: After the coating is prepared, turn off the power and nitrogen source, keep the flow of argon, and keep it warm at 750°C for 60 minutes under the protection of argon;

Step 2: After 60 minutes of heat preservation, slowly cool to room temperature in a vacuum chamber at a rate of -5°C/min.

The superlattice tough high-entropy alloy nitride ceramic coating is applied to wear-resistant, corrosion-resistant and high-temperature-resistant surface functional coatings of nuclear power facilities, processing tools, aerospace equipment or medical devices.

The beneficial effects of the present invention are:

The nitride ceramic coating of the present invention is annealed at 750°C for one hour, and the hardness of the superlattice high-entropy alloy nitride ceramic coating obtained is greater than 40GPa, which meets the requirements of superhard materials, and the fracture toughness exceeds 5MPa·m ^1/2 , realizing The effect of simultaneous hardening and toughening on high-entropy nitride ceramic thin films. The superlattice strong and tough high-entropy alloy nitride ceramic coating provided by the invention has broad application prospects in the fields of advanced coating processing tools, aerospace equipment and the like.

The invention can be widely used in wear-resistant, corrosion-resistant and high-temperature-resistant surface functional coatings of nuclear power facilities, processing tools, aerospace equipment or medical equipment.

Description of drawings

Fig. 1 is the X-ray diffraction spectrum of the superlattice tough high-entropy alloy nitride ceramic coating prepared in the embodiment. As shown in Figure 1, the coating presents a clear single-phase face-centered cubic structure.

Fig. 2 is the load-displacement curve of the superlattice tough high-entropy alloy nitride ceramic coating prepared in the embodiment.

Implementation

The following structural drawings and embodiments further illustrate the present invention.

Example

As shown in Figure 1-Figure 2.

A superlattice tough high-entropy alloy nitride ceramic coating is prepared through the following steps:

1. Substrate cleaning. The cemented carbide substrate was selected, ultrasonically cleaned with acetone and absolute ethanol for 15 minutes respectively, dried with nitrogen, and then placed into the cavity of the magnetron sputtering equipment.

2. Plasma activation of the substrate surface. Turn on the mechanical pump and the molecular pump in sequence, vacuumize the chamber to 5.0×10 ^{- 4} Pa, feed high-purity argon to control the pressure in the vacuum chamber to 0.8Pa, control the pulse bias to -600V, and glow discharge to generate plasma , and activate and clean the surface of the substrate for 30 minutes.

3. Preparation of high-entropy alloy transition layer. Control the flow rate of Ar to adjust the air pressure to 0.8Pa. Turn on the radio frequency power supply connected in series with the metal target of simple substance Ti, pulse bias -150V, and deposit a Ti transition layer with a thickness of 200nm.

4. Feed in N ₂ , adjust the flow ratio of N ₂ and Ar to 1:2, the air pressure to 0.5Pa, keep the output power ratio of the RF power supply connected to the TiZrNbMoHf and TiZrNbMoTa high-entropy alloy targets at 1:1, and pulse bias -70V , the deposition temperature is 450°C, the baffles above the TiZrNbMoHf and TiZrNbMoTa alloy targets are controlled to open alternately every 30s (the baffles above TiZrNbMoHf are opened, and the baffles above TiZrNbMoTa are closed). The modulation period is 5nm, and the total thickness is 2µm. High-entropy ceramic coatings.

5. After the coating is prepared, annealing is carried out under the protection of argon to improve or eliminate the tissue defects and residual stress generated during the coating preparation process, and prevent the coating from cracking and peeling, including the following steps:

Step 1: After the coating is prepared, turn off the power and nitrogen source, keep the flow of argon, and keep it warm at 750°C for 60 minutes under the protection of argon;

Step 2: After 60 minutes of heat preservation, slowly cool to room temperature in a vacuum chamber at a rate of -5°C/min.

The superlattice tough high-entropy alloy nitride ceramic coating is applied to wear-resistant, corrosion-resistant and high-temperature-resistant surface functional coatings of nuclear power facilities, processing tools, aerospace equipment or medical devices.

6. The hardness of the high-entropy nitride ceramic coating prepared in this example was tested by nanoindentation method, and the hardness was 41.37GPa. The micromechanical cantilever bending test was carried out by using the in-situ nanomechanical system, and the fracture toughness of the coating was measured to be 5.2MPa · m ^1/2 . The X-ray diffraction spectrum is shown in Figure 1, and the coating presents a clear single-phase face-centered cubic structure. The load-displacement curve is shown in Figure 2.

Example

A superlattice tough high-entropy alloy nitride ceramic coating is prepared through the following steps:

1. Substrate cleaning. The cemented carbide substrate was selected, ultrasonically cleaned with acetone and absolute ethanol for 15 minutes respectively, dried with nitrogen, and then placed into the cavity of the magnetron sputtering equipment.

2. Plasma activation of the substrate surface. Turn on the mechanical pump and the molecular pump in sequence, vacuumize the chamber to 5.0×10 ^{- 4} Pa, pass high-purity argon gas to control the pressure in the vacuum chamber to 0.33Pa, control the pulse bias to -800V, and glow discharge to generate plasma , and activate and clean the surface of the substrate for 30 minutes.

3. Preparation of high-entropy alloy transition layer. Control the flow rate of Ar to adjust the air pressure to 0.4Pa. Turn on the radio frequency power supply connected in series with the metal target of simple substance Ti, pulse bias -150V, and deposit a Ti transition layer with a thickness of 100nm.

4. Feed in N ₂ , adjust the flow ratio of N ₂ and Ar to 1:4, the air pressure to 0.4Pa, keep the output power ratio of the RF power supply connected to the TiZrNbMoHf and TiZrNbMoW high-entropy alloy targets at 1:1, pulse bias -200V , the deposition temperature is 350°C, and the baffles above the TiZrNbMoHf and TiZrNbMoW alloy targets are controlled to open alternately every 15s (the baffles above TiZrNbMoHf are opened, and the baffles above TiZrNbMoW are closed). The modulation period is 2nm, and the total thickness is 1µm. High-entropy ceramic coatings.

5. After the coating is prepared, annealing is carried out under the protection of argon to improve or eliminate the tissue defects and residual stress generated during the coating preparation process, and prevent the coating from cracking and peeling, including the following steps:

Step 1: After the coating is prepared, turn off the power and nitrogen source, keep the flow of argon, and keep it warm at 750°C for 60 minutes under the protection of argon;

Step 2: After 60 minutes of heat preservation, slowly cool to room temperature in a vacuum chamber at a rate of -5°C/min.

The superlattice tough high-entropy alloy nitride ceramic coating is applied to wear-resistant, corrosion-resistant and high-temperature-resistant surface functional coatings of nuclear power facilities, processing tools, aerospace equipment or medical devices.

6. The hardness of the high-entropy nitride ceramic coating prepared in this example was tested by nano-indentation method, and the hardness was 41.87GPa. The fracture toughness of the coating was measured to be 5.22MPa by the in-situ nanomechanical system for micro-mechanical cantilever bending test. · m ^1/2 .

Example

A superlattice tough high-entropy alloy nitride ceramic coating is prepared through the following steps:

1. Substrate cleaning. The cemented carbide substrate was selected, ultrasonically cleaned with acetone and absolute ethanol for 15 minutes respectively, dried with nitrogen, and then placed into the cavity of the magnetron sputtering equipment.

2. Plasma activation of the substrate surface. Turn on the mechanical pump and the molecular pump in sequence, vacuumize the chamber to 5.0×10 ^{- 4} Pa, feed high-purity argon to control the pressure in the vacuum chamber to 0.5Pa, control the pulse bias to -700V, and glow discharge to generate plasma , and activate and clean the surface of the substrate for 30 minutes.

3. Preparation of high-entropy alloy transition layer. Control the flow rate of Ar to adjust the air pressure to 0.4Pa. Turn on the radio frequency power supply connected in series with the metal target of simple substance Ti, pulse bias -150V, and deposit a Ti transition layer with a thickness of 500nm.

4. Feed in N ₂ , adjust the flow ratio of N ₂ and Ar to 1:1, the air pressure to 0.8Pa, keep the output power ratio of the RF power supply connected to the TiZrNbMoHf and TiZrHfNbTaN high-entropy alloy targets at 1:1, pulse bias -120V , the deposition temperature was 400°C, and the baffles above the TiZrNbMoHf and TiZrHfNbTaN alloy targets were controlled to open alternately every 150s (the baffles above TiZrNbMoHf were opened, and the baffles above TiZrHfNbTaN were closed). Lattice high-entropy ceramic coatings.

5. After the coating is prepared, annealing is carried out under the protection of argon to improve or eliminate the tissue defects and residual stress generated during the coating preparation process, and prevent the coating from cracking and peeling, including the following steps:

Step 1: After the coating is prepared, turn off the power and nitrogen source, keep the flow of argon, and keep it warm at 750°C for 60 minutes under the protection of argon;

Step 2: After 60 minutes of heat preservation, slowly cool to room temperature in a vacuum chamber at a rate of -5°C/min.

The superlattice tough high-entropy alloy nitride ceramic coating is applied to wear-resistant, corrosion-resistant and high-temperature-resistant surface functional coatings of nuclear power facilities, processing tools, aerospace equipment or medical devices.

6. The hardness of the high-entropy nitride ceramic coating prepared in this example was tested by the nano-indentation method, and the hardness was 43.54GPa. The micro-mechanical cantilever bending test was carried out by the in-situ nanomechanical system, and the fracture toughness of the coating was measured to be 5.1MPa · m ^1/2 .

The parts not involved in the present invention are the same as the prior art or can be realized by adopting the prior art.

Claims (6)

1. The superlattice tough high-entropy alloy nitride ceramic coating is characterized in that the superlattice structure is formed by alternately depositing two high-entropy alloy nitride ceramics with face-centered cubic (fcc) structures in a nano-scale thickness.

2. The superlattice tough high-entropy alloy nitride ceramic coating according to claim 1, wherein the two face-centered cubic structured high-entropy alloy nitrides are a combination of any two of TiZrNbMoHfN, tiZrNbMoTaN, tiZrNbMoWN and tizrshfnbtan.

3. The superlattice tough high-entropy alloy nitride ceramic coating according to claim 1, characterized in that the superlattice structure modulation period, i.e. the thickness of each layer of nitride is 2-25 nm, the hardness of the obtained superlattice high-entropy alloy nitride ceramic coating is more than 40GPa, the requirement of superhard material is met, and the fracture toughness exceeds 5 MPa-m ^1/2 The effect of toughening the high-entropy nitride ceramic film while increasing the hardness is achieved.

4. A method for preparing the superlattice tough high-entropy alloy nitride ceramic coating according to claim 1, which is characterized by comprising the following steps:

placing a substrate in a vacuum cavity, introducing high-purity argon, controlling the air pressure of the vacuum cavity to be 0.33-0.8 Pa, controlling the pulse bias to be-800 to-600V, and activating and cleaning the surface of the substrate by using plasma generated by argon glow discharge;

secondly, ti transition layer deposition with the magnetron sputtering thickness of 200-500 nm is carried out on the surface of the substrate, the magnetron sputtering air source of the transition layer is argon, and the air pressure of a magnetron sputtering chamber is 0.4-0.8 Pa; the cathode target material of the magnetron sputtering is a metal target material of Ti simple substance;

thirdly, performing radio frequency reaction magnetron sputtering deposition of a high-entropy nitride ceramic coating on the surface of the alloy transition layer, wherein a radio frequency reaction magnetron sputtering gas source is argon and nitrogen, the flow ratio of the nitrogen to the argon is (0.25-1): 1, and the working pressure of a reaction magnetron sputtering chamber is 0.4-0.8 Pa; the cathode target of the radio frequency reaction magnetron sputtering is TiZrNbMoHf, tiZrNbMoTa, tiZrNbMoW or TiZrHfNbTa in the high-entropy alloy target; the bias voltage applied to the sample is-70 to-200V; the deposition temperature is 350-450 ℃; the double-layer periodic superlattice structure is realized by opening and closing a baffle plate controlled by a computer above an alloy target material combined by TiZrNbMoHf-TiZrNbMoTa or TiZrNbMoW-TiZrHfNbTa.

5. The method of claim 4, wherein the annealing is performed under argon protection after the coating is prepared, thereby improving or eliminating the structural defects and residual stress generated during the coating preparation process and preventing the cracking and peeling of the coating, comprising the steps of:

step one: after the coating is prepared, the power supply and the nitrogen source are turned off, the argon flow is maintained, and the temperature is kept for 60min at 750 ℃ under the protection of argon;

step two: after the heat preservation is finished for 60min, slowly cooling to room temperature in the vacuum cavity at a speed of-5 ℃/min.

6. A superlattice tough high-entropy alloy nitride ceramic coating according to claim 1, which is characterized by being applied to a wear-resistant, corrosion-resistant and high-temperature-resistant surface functional coating of nuclear power facilities, processing tools, aerospace equipment or medical instruments.