A tough, corrosion-resistant non-equimolar high-entropy nitride ceramic coating and preparation method thereof

Abstract

A tough, corrosion-resistant, non-equimolar #imgabs0# high-entropy nitride ceramic coating and a preparation method thereof, wherein the chemical composition of the high-entropy nitride ceramic coating is #imgabs1# (where #imgabs2#), and the element ratio (x i and y), so that the valence electron concentration (VEC) of the coating system is close to the optimal value, thereby obtaining a high-entropy nitride coating with optimal mechanical and chemical properties. The non-equimolar #imgabs3# high-entropy nitride ceramic material provided by the present invention is a single-phase face-centered cubic structure, with a hardness greater than 28GPa and a fracture toughness H 3 / E 2 The high entropy nitride ceramic coating provided by the present invention can meet the performance requirements of applications in the fields of nuclear power facilities, processing tools, aerospace equipment or medical equipment.

Description

Technical Field

[0001] The present invention relates to the technical field of material surface coating, in particular to a multi-component composite ceramic coating technology, specifically a strong, tough and corrosion-resistant High entropy nitride ceramic coating and preparation method thereof. Background Art

[0002] Nitride ceramic coatings are widely used in mechanical manufacturing such as cutting tools and molds, as well as high-end equipment such as aviation, aerospace, and nuclear energy due to their 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, high thermal conductivity, and ablation resistance. However, with the continuous development of manufacturing and high-end equipment, the requirements for the comprehensive performance of coatings are getting higher and higher. Traditional binary (NbN, ZrN, TiN, HfN, etc.) and ternary (TiAlN) nitride coatings are gradually unable to meet the requirements of harsh service environments and working conditions. High-entropy ceramics are solid solutions based on interstitial phases, containing 4 or more metal elements. Due to the unique physical and mechanical properties given to high-entropy nitrides by entropy stability, they surpass traditional nitride ceramics in hardness, fracture toughness, corrosion resistance, and high-temperature stability. Therefore, high-entropy ceramics have attracted more and more attention.

[0003] To date, almost all research work on high-entropy ceramics has focused on five-component equimolar compositions. Recent studies have found non-equimolar high-entropy ceramics with better thermal insulation and higher hardness in non-equimolar compositions with optimal oxygen vacancies. Compared with high-entropy ceramics, the diverse categories of non-equimolar high-entropy ceramics provide more possibilities to tailor the composition and defects, and thus tailor various properties. Summary of the invention

[0004] The purpose of the present invention is to solve the problems that the existing high entropy nitride coatings have poor operability, difficult to improve performance, and difficult to develop, and to invent a strong, tough, and corrosion-resistant High entropy nitride ceramic coating and preparation method thereof. The high entropy nitride ceramic design method based on valence electron concentration provided by the present invention can efficiently select a variety of high entropy nitride ceramics with excellent physical and chemical properties from tens of thousands of potential non-equimolar high entropy nitride ceramics. The chemical composition provided by the present invention is The non-equimolar high-entropy nitride ceramics have high hardness, high fracture toughness and excellent corrosion resistance.

[0005] One of the technical solutions of the present invention is:

[0006] A strong and corrosion-resistant The high entropy nitride ceramic coating is characterized in that the element content is: transition metal elements such as Ti, Zr, Hf, Nb, Mo, etc., the molar fraction of each element is between 5 and 15%, and is not equal, and nitrogen is used for balance.

[0007] The amount is: transition metal elements such as Ti, Zr, Hf, Nb, Mo, etc. The molar fraction of each element is between 5 and 15%, and is not equal, and nitrogen is used for balance.

[0008] In the non-equimolar single-phase high-entropy nitride ceramic coating provided by the present invention, the molar fractions of transition metal elements such as Ti, Zr, Hf, Nb, Mo, etc. are not strictly equal or similar, that is, x1, x2, x3, x4, x5 and y are independent of each other.

[0009] Preferably, the crystal structure of the tough and corrosion-resistant high-entropy nitride ceramic coating is an FCC structure.

[0010] The tough and corrosion-resistant high entropy nitride ceramic coating of the present invention has a strong and corrosion-resistant property in the valence electron concentration (VEC = 4*(x1+x2+x3)+5*x4+6*x5+5*y, stoichiometric ratio ) equals 9.5±0.5.

[0011] The second technical solution of the present invention is:

[0012] A strong and corrosion-resistant The high entropy nitride ceramic coating is characterized by comprising the following steps:

[0013] Step 1: Evacuate the cavity, introduce high-purity argon gas to control the gas pressure to 0.33-0.8 Pa, control the medium frequency power supply to excite the argon glow discharge to generate plasma, and activate and clean the substrate surface.

[0014] Step 2: Apply a high entropy alloy transition layer with a chemical composition of TiZrHfNbMo and a thickness of 200 to 500 nm between the substrate and the FCC high entropy nitride ceramic coating.

[0015] Step 3: Perform radio frequency reactive magnetron sputtering deposition on the surface of the high entropy alloy transition layer to obtain a chemical composition of The high entropy nitride ceramic material is prepared, the RF reactive magnetron sputtering gas source comprises argon and nitrogen, the flow ratio of nitrogen to argon is (0.25-1):1, and the pressure of the reactive magnetron sputtering gas source is 0.4-0.8 Pa; the cathode target material of the RF reactive magnetron sputtering is a metal target material of Ti, Zr, Hf, Nb, or Mo; the bias voltage applied to the sample is 200-120 V; and the deposition temperature is 350-450° C.

[0016] Preferably, the thickness of the high entropy nitride ceramic layer prepared by the method is 1 to 8 μm.

[0017] The present invention provides the use of the ceramic coating described in the above technical solution or the ceramic coating prepared by the preparation method described in the above technical solution in the surface coating of tools, cutting tools, molds, aerospace equipment, nuclear energy equipment or medical equipment.

[0018] The beneficial effects of the present invention are:

[0019] The high entropy nitride ceramic coating provided by the present invention has a chemical composition of The element content is as follows: the molar fraction of transition metal elements such as Ti, Zr, Hf, Nb, and Mo is 5 to 15%, and the nitrogen element is balanced; the transition metal elements such as Ti, Zr, Hf, Nb, and Mo are not equimolar, that is, x1, x2, x3, x4, x5, and y are independent of each other. High entropy nitride ceramic coating is a multi-principal nitride ceramic coating. It utilizes the cocktail effect, high entropy effect and solid solution strengthening effect of binary nitride ceramics (TiN, ZrN, HfN, NbN, MoN) to maximize the role of each transition metal element nitride ceramic, and can simultaneously improve the mechanical properties and high-temperature stability of the high-entropy nitride ceramic coating, thereby obtaining a high-entropy nitride ceramic coating with high hardness, high wear resistance, high fracture toughness and excellent high-temperature stability.

[0020] The preparation method provided by the present invention comprises the following steps: using radio frequency reactive magnetron sputtering, the reactive sputtering gas source comprises a nitrogen source and an inert gas, and the cathode target material is a metal target material of Ti, Zr, Hf, Nb, and Mo simple substance, and depositing it on the surface of the substrate to obtain a chemical composition of The preparation method provided by the present invention can reduce the metal droplets in the ceramic coating, improve the compactness of the high entropy nitride ceramic coating, and help improve the mechanical properties of the high entropy ceramic.

[0021] The ceramic coating provided by the present invention comprises a transition layer and a nitride ceramic layer arranged on the surface of the transition layer. The ceramic coating provided by the present invention comprises a transition layer, and the transition layer can eliminate the difference in thermal expansion coefficient between the substrate and the nitride ceramic layer, and improve the bonding force between the nitride ceramic layer and the substrate. The ceramic coating provided by the present invention comprises a nitride ceramic layer, and the material of the nitride ceramic layer is a chemical composition of The high-entropy nitride ceramic material has high hardness, excellent wear resistance and low friction coefficient. The results of the embodiments show that when the ceramic coating provided by the present invention is tested for hardness by nanoindentation method, the hardness is 29.92-38.15 GPa; when the dry friction performance test is performed, the friction coefficient of the ceramic coating in the stable stage is 0.37-0.49; when the ceramic coating is subjected to a friction and wear test, after a 60-minute linear reciprocating friction and wear test under 10N-5Hz high-frequency heavy load conditions, the coating does not peel off or wear through.

[0022] The method for preparing the ceramic coating of the technical solution provided by the present invention comprises the following steps: performing reactive radio frequency magnetron sputtering deposition on the surface of the transition layer to obtain a ceramic coating having a chemical composition of The high entropy nitride ceramic layer is prepared by the radio frequency reactive magnetron sputtering gas source including a nitrogen source and an inert gas, and the cathode target material of the radio frequency magnetron sputtering is a metal target material of Ti, Zr, Hf, Nb, and Mo. The preparation method provided by the present invention uses radio frequency reactive magnetron sputtering to deposit a nitride ceramic layer on the surface of the transition layer, which can further improve the adhesion strength of the ceramic coating and break through the limitation of the target material poisoning on the coating thickness. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a surface morphology of the high entropy nitride ceramic coating prepared in Example 1, obtained by magnifying it 20,000 times under a scanning electron microscope.

[0024] Figure 2 Schematic diagram of the structure of the high entropy nitride ceramic coating prepared in Example 1.

[0025] Figure 3 The high entropy nitride ceramic coating prepared in Example 1 was subjected to atmospheric conditions (5N-5Hz-60min- 6mmZrO2) surface wear morphology. DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0027] Example 1.

[0028] like Figure 1-Figure 3 shown.

[0029] A strong and corrosion-resistant A high entropy nitride ceramic coating, wherein x1, x2, x3, x4, x5 and y are 0.22, 0.25, 0.11, 0.28, 0.14 and 1, respectively, and the preparation method thereof is as follows:

[0030] 1. Matrix cleaning: Select a cemented carbide matrix, use acetone and anhydrous ethanol to ultrasonically clean it for 15 minutes respectively, blow it dry with nitrogen, and then put it into the cavity of the magnetron sputtering equipment.

[0031] 2. Plasma activation on the substrate surface. The medium frequency power supply generates plasma through glow discharge, which activates and cleans the substrate surface for 30 minutes to improve the adhesion of the coating.

[0032] 3. Preparation of high entropy alloy transition layer. Control the Ar flow rate to adjust the gas pressure to 0.8 Pa. Turn on the RF power supply in series with the metal targets of Ti, Zr, Hf, Nb, and Mo respectively, with a pulse bias of 150 V, and deposit a TiZrHfNbMo transition layer with a thickness of 500 nm.

[0033] 4. Preparation of high entropy nitride ceramic coating. N2 was introduced, and the flow ratio of N2 and Ar was adjusted to 3:7, the gas pressure was 0.6Pa, the pulse bias was 150V, and the deposition thickness was 4.5μm. High entropy ceramic coating. In this embodiment, the values ​​of x1, x2, x3, x4, x5 and y are 0.22, 0.25, 0.11, 0.28, 0.14 and 1 respectively.

[0034] like Figure 2 As shown, in the first step, RF magnetron sputtering is used to prepare a high entropy ceramic transition layer with a thickness of 200 to 500 nm and a composition of TiZrHfNbMo on the surface of the substrate; in the second step, nitrogen source gas is introduced and reactive RF magnetron sputtering is used to prepare a high entropy nitride ceramic coating with a thickness of 1 to 8 μm on the surface of the transition layer.

[0035] 5. The hardness of the high entropy nitride ceramic coating prepared in this example was tested by nanoindentation method, and the hardness was 38.15 GPa.

[0036] like Figure 1 As shown, the coating surface of this embodiment is dense and free of microscopic defects such as tiny holes and metal droplets.

[0037] like Figure 3 As shown, the high entropy nitride ceramic coating prepared in this embodiment did not peel off or wear through within 60 minutes under high speed, heavy load and dry friction conditions.

[0038] Example 2.

[0039] A strong and corrosion-resistant A high entropy nitride ceramic coating, wherein x1, x2, x3, x4, x5 and y are 0.27, 0.24, 0.15, 0.29, 0.22 and 0.83 respectively, and the preparation method thereof is as follows:

[0040] 1. Substrate cleaning: Select the TC4 substrate, use acetone and anhydrous ethanol to ultrasonically clean it for 15 minutes respectively, blow dry it with nitrogen and put it into the cavity of the magnetron sputtering equipment.

[0041] 2. Plasma activation on the substrate surface. The medium frequency power supply generates plasma through glow discharge, which activates and cleans the substrate surface for 30 minutes to improve the adhesion of the coating.

[0042] 3. Preparation of high entropy alloy transition layer. Control the Ar flow rate to adjust the gas pressure to 0.8 Pa. Turn on the RF power supply in series with the metal targets of Ti, Zr, Hf, Nb, and Mo respectively, with a pulse bias of 150 V, and deposit a TiZrHfNbMo transition layer with a thickness of 500 nm.

[0043] 4. Preparation of high entropy nitride ceramic coating. N2 was introduced, and the flow ratio of N2 and Ar was adjusted to 3:7, the gas pressure was 0.6Pa, the pulse bias voltage was 150V, and the deposition thickness was 1.5μm. High entropy ceramic coating. In this embodiment, the values ​​of x1, x2, x3, x4, x5 and y are 0.27, 0.24, 0.15, 0.29, 0.22 and 0.83 respectively.

[0044] 5. The hardness of the high entropy nitride ceramic coating prepared in this example was tested by nanoindentation method, and the hardness was 33.12 GPa.

[0045] 6. The test was carried out in accordance with the method specified in the National Standard 10125 2012 Artificial Atmosphere Corrosion Test Salt Spray Test. Specifically, a sodium chloride solution with a pH value of 6.5 was sprayed into a closed salt spray test chamber through a spray device. The sample was placed in the salt spray test chamber and the surface of the sample was intermittently observed for rust. After being placed for 1000 hours, no rust was found on the surface of the sample after it was taken out.

[0046] Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] The present invention does not involve parts that are the same as the prior art or can be implemented by using the prior art.

Claims

1. A non-equimolar single-phase tough and corrosion-resistant High entropy nitride ceramic coating, characterized in that The element content of the high entropy nitride ceramic coating is: the molar fraction of the transition metal elements Ti, Zr, Hf, Nb, and Mo is between 5% and 15% and is not equal; the stoichiometric ratio of the transition metal elements Ti, Zr, Hf, Nb, and Mo in the high entropy nitride ceramic is , , , and are independent of each other. When VEC=9.5±0.5, the high entropy nitride ceramic has strong and tough corrosion resistance. , stoichiometric ratio .

2. A non-equimolar single-phase tough corrosion-resistant material as claimed in claim 1 A method for preparing a high entropy nitride ceramic coating, characterized in that it The following steps are involved: Step 1: Place the substrate in a vacuum chamber, introduce high-purity argon gas to control the vacuum chamber pressure to 0.33~0.8Pa, control the medium frequency power supply to excite argon glow discharge, and activate and clean the substrate surface; Step 2: Depositing an equal molar transition layer of Ti, Zr, Hf, Nb and Mo alloys with a thickness of 200 to 500 nm by magnetron sputtering on the substrate surface, the transition layer magnetron sputtering gas source is argon, and the pressure of the magnetron sputtering chamber is 0.4 to 0.8 Pa; the cathode target material of the magnetron sputtering is a metal target material of Ti, Zr, Hf, Nb and Mo; Step three: RF reactive magnetron sputtering deposition of high entropy nitride ceramic coating is carried out on the surface of the alloy transition layer. The gas sources of RF reactive magnetron sputtering are argon and nitrogen, the flow ratio of nitrogen and argon is (0.25~1):1, and the working pressure of the reactive magnetron sputtering chamber is 0.4~0.8Pa; the cathode target material of RF reactive magnetron sputtering is a metal target material of Ti, Zr, Hf, Nb, and Mo; the bias voltage applied to the sample is 200~120V; the deposition temperature is 350~450℃.

3. The method according to claim 2, characterized in that The high entropy nitride ceramic coating has a single-phase face-centered cubic structure, a hardness greater than 28 GPa, and a fracture toughness H 3 / E 2 Over 0.58, able to withstand neutral salt spray corrosion for not less than 1000 hours.

4. The method according to claim 2, characterized in that: The thickness of the high entropy nitride ceramic layer prepared by the method is 1 to 8 μm.

Images