A high-entropy alloy wear-resistant composite coating and a preparation method thereof

Abstract

A high-entropy alloy wear-resistant composite coating and its preparation method are disclosed, belonging to the field of surface modification technology. The preparation method includes the following steps: 1) subjecting a high-entropy alloy substrate to thermal oxidation treatment in an oxygen-containing atmosphere at a reaction temperature of 400–600℃ to form an oxide layer on the surface of the high-entropy alloy substrate; 2) placing the high-entropy alloy substrate treated in step 1) into a high-purity nitrogen atmosphere for nitriding treatment at a reaction temperature of 700–1200℃ to grow a nitriding layer on the surface of the oxide layer, forming a wear-resistant composite coating. The preparation method of the high-entropy alloy wear-resistant composite coating has high production efficiency, low production cost, and can achieve mass production. It can generate distinct oxide and nitriding layers on the surface of the high-entropy alloy substrate, significantly improving the wear resistance and surface hardness of the high-entropy alloy substrate.

Description

Technical Field

[0001] This invention belongs to the field of surface modification technology, specifically relating to a high-entropy alloy wear-resistant composite coating and its preparation method. Background Technology

[0002] Biomedical metals primarily utilize titanium alloys and titanium-based high-entropy alloys. While titanium alloys possess significant advantages such as high specific strength, excellent mid-to-high temperature performance, and corrosion resistance, they also suffer from drawbacks including low surface hardness and poor wear resistance. High-entropy alloys (HEAs) are single-phase solid solution structures formed by five or more elements. HEAs exhibit superior specific strength, fracture resistance, tensile strength, corrosion resistance, and oxidation resistance compared to traditional alloys; however, their surface hardness and wear resistance still fail to meet the requirements for biomedical metals.

[0003] Surface modification processes can effectively improve the hardness, corrosion resistance, and wear resistance of alloys. Commonly used surface modification processes for titanium alloys include chemical treatment, ion implantation, vapor deposition, laser cladding, and thermal spraying. However, these generally suffer from high preparation costs, high porosity, and low bonding strength between the coating and the substrate. Thermal oxidation is a simple, effective, and low-cost surface modification process. Patent CN202211292223.0 proposes a method for preparing high-wear-resistant and corrosion-resistant high-entropy alloys. The steps include preparing a high-entropy alloy and then subjecting it to thermal oxidation treatment at a temperature of 950-1050℃ for 10-360 minutes. While thermal oxidation reduces coating wear, it sacrifices the surface friction coefficient to some extent. Composite layers constructed with two ceramic layers of different elements can effectively overcome the problems of single-element layers. However, conventional composite layers use high-cost surface modification techniques such as ion implantation, which are unsuitable for surface modification of alloy products with large surface areas. Summary of the Invention

[0004] In order to overcome the shortcomings of the prior art, one of the objectives of this invention is to provide a method for preparing a high-entropy alloy wear-resistant composite coating, which can generate a modified composite layer composed of an oxide layer and a nitriding layer on the surface of a high-entropy alloy substrate, thereby significantly improving the wear resistance and surface hardness of the high-entropy alloy substrate.

[0005] The second objective of this invention is to provide a high-entropy alloy wear-resistant composite coating, which has the characteristics of ultra-high wear resistance and high surface hardness.

[0006] One of the objectives of this invention is achieved through the following technical solution:

[0007] A method for preparing a high-entropy alloy wear-resistant composite coating includes the following steps:

[0008] 1) The high-entropy alloy substrate is subjected to thermal oxidation treatment in an oxygen-containing atmosphere at a reaction temperature of 400-600℃ to form an oxide layer on the surface of the high-entropy alloy substrate;

[0009] 2) The high-entropy alloy substrate after step 1) is placed in a high-purity nitrogen atmosphere for nitriding treatment at a reaction temperature of 700-1200℃. A nitriding layer is grown on the surface of the oxide layer to form a wear-resistant composite coating.

[0010] Furthermore, in step 1), the gas in the oxygen-containing atmosphere includes flowing air or pure oxygen; the thermal oxidation treatment time is 1 to 3 hours.

[0011] Furthermore, in step 2), the purity of the high-purity nitrogen gas is ≥99.99%; the nitriding treatment time is 1-3 hours.

[0012] Further, in step 1), the apparatus for thermal oxidation treatment includes any one of a tube furnace, a pit-type gas nitriding furnace, and an atmosphere-protected muffle furnace;

[0013] In step 2), the nitriding treatment apparatus includes any one of a pit-type gas nitriding furnace, a gas carburizing and nitriding furnace, and a tube furnace.

[0014] Further, in step 1), the heating rate of the thermal oxidation treatment apparatus is 8-12 °C / min;

[0015] In step 2), the heating rate of the nitriding treatment device is 8-12 °C / min.

[0016] Furthermore, step 1) also includes the pretreatment of the high-entropy alloy substrate, wherein the pretreatment process includes grinding, polishing, cleaning and drying the high-entropy alloy substrate in sequence.

[0017] Furthermore, the polishing process uses 100-5000 grit SiC sandpaper for polishing.

[0018] The surface of the high-entropy alloy substrate is polished using 70-100nm silicon oxide polishing slurry and / or 40-60nm aluminum oxide polishing slurry.

[0019] The cleaning process involves cleaning with anhydrous ethanol followed by rinsing with deionized water.

[0020] Furthermore, the high-entropy alloy matrix comprises TiZrNbTaMo alloys.

[0021] Furthermore, the high-entropy alloy matrix is ​​prepared by any one of the following methods: electric arc melting, induction melting, or vacuum suspension melting.

[0022] The second objective of this invention is achieved by the following technical solution:

[0023] A high-entropy alloy wear-resistant composite coating is prepared by the aforementioned method for preparing high-entropy alloy wear-resistant composite coatings.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] The present invention discloses a method for preparing a high-entropy alloy wear-resistant composite coating, which has high production efficiency, low production cost, and can achieve mass production. It can generate a distinct oxide layer and a nitriding layer on the surface of a high-entropy alloy substrate, significantly improving the wear resistance and surface hardness of the high-entropy alloy substrate.

[0026] The present invention discloses a high-entropy alloy wear-resistant composite coating. Compared with existing single-element single-layer coatings such as TiC, TiN, and TiO2, the thickness of this composite coating can be adjusted, and it has higher hardness, lower friction coefficient, and ultra-high wear resistance. It has broad application prospects in fields such as biomedicine, high-temperature conditions, marine engineering, and chemical engineering. Attached Figure Description

[0027] Figure 1 This is a comparison diagram of the microhardness of the product in Example 1 of this invention.

[0028] Figure 2 This is a comparison chart of the wear rate of the product in Example 1 of this invention.

[0029] Figure 3 This is a comparison chart of the friction coefficients of the products in Example 1 of this invention.

[0030] Among them, TZNTM-RT is a cast high-entropy alloy substrate; TZNTM-500O-1000N is the product of Example 1. Detailed Implementation

[0031] The present invention will now be further described in conjunction with specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0032] Example 1

[0033] A method for preparing a high-entropy alloy wear-resistant composite coating includes the following steps:

[0034] 1) Preparation of TiZrNbTaMo high-entropy alloy matrix;

[0035] The specific operation includes: weighing equal amounts of raw materials of each element, placing them in a vacuum arc melting furnace, and adjusting the vacuum level to below 10. -5Pa, filled with argon protective gas at a pressure of 0.05 MPa; repeatedly melted at least 5 times to ensure uniform alloy composition, obtaining a TiZrNbTaMo high-entropy alloy matrix; then using CNC wire cutting to cut alloy disc substrates with a diameter of 8 mm and a thickness of 1.5 mm for the following steps.

[0036] 2) Pre-treat the surface of the high-entropy alloy substrate; the pre-treatment process includes sequentially grinding, polishing, cleaning and drying the high-entropy alloy substrate;

[0037] The grinding process uses 3000-grit SiC sandpaper; the polishing process uses 80nm silicon dioxide polishing slurry and 60nm aluminum oxide polishing slurry to polish the surface of the high-entropy alloy substrate; and the cleaning process uses anhydrous ethanol for cleaning, followed by deionized water rinsing.

[0038] 3) The high-entropy alloy substrate is placed in a tube furnace and heated at a rate of 10°C / min in an oxygen-containing atmosphere. After thermal oxidation treatment at 500°C for 2 hours, it is allowed to cool naturally in the furnace to form an oxide layer on the surface of the high-entropy alloy substrate. The gas in the oxygen-containing atmosphere includes flowing air or pure oxygen.

[0039] 4) The high-entropy alloy substrate treated in step 3) is placed in a pit-type gas nitriding furnace and heated at a rate of 10℃ / min under a high-purity nitrogen atmosphere. After nitriding at 1000℃ for 2 hours, it is allowed to cool naturally with the furnace. A nitriding layer is grown on the surface of the oxide layer to form a wear-resistant composite coating. The purity of the high-purity nitrogen gas is ≥99.99%.

[0040] Example 2

[0041] A method for preparing a high-entropy alloy wear-resistant composite coating includes the following steps:

[0042] 1) Prepare the same TiZrNbTaMo high-entropy alloy matrix as in Example 1;

[0043] 2) Pre-treat the surface of the high-entropy alloy substrate; the pre-treatment process includes sequentially grinding, polishing, cleaning and drying the high-entropy alloy substrate;

[0044] Among them, 100-mesh SiC sandpaper is used for polishing in the polishing process;

[0045] In the polishing process, 100nm silicon oxide polishing slurry and 40nm aluminum oxide polishing slurry are used to polish the surface of the high-entropy alloy substrate.

[0046] The cleaning process involves cleaning with anhydrous ethanol followed by rinsing with deionized water.

[0047] 3) The high-entropy alloy substrate is placed in a tube furnace and heated at a rate of 12°C / min in an oxygen-containing atmosphere. After thermal oxidation treatment at 600°C for 1 hour, it is naturally cooled with the furnace to form an oxide layer on the surface of the high-entropy alloy substrate. The gas in the oxygen-containing atmosphere includes flowing air or pure oxygen.

[0048] 4) The high-entropy alloy substrate after step 3) is placed in a pit-type gas nitriding furnace and heated at a rate of 12℃ / min under a high-purity nitrogen atmosphere. After nitriding at 1200℃ for 1 hour, it is allowed to cool naturally with the furnace. A nitriding layer is grown on the surface of the oxide layer to form a wear-resistant composite coating. The purity of the high-purity nitrogen gas is ≥99.99%.

[0049] Example 3

[0050] A method for preparing a high-entropy alloy wear-resistant composite coating includes the following steps:

[0051] 1) Prepare the same TiZrNbTaMo high-entropy alloy matrix as in Example 1;

[0052] 2) Pre-treat the surface of the high-entropy alloy substrate; the pre-treatment process includes sequentially grinding, polishing, cleaning and drying the high-entropy alloy substrate;

[0053] Among them, 5000-grit SiC sandpaper is used for polishing in the polishing process;

[0054] The surface of the high-entropy alloy substrate is polished using 70nm silicon oxide polishing slurry and 60nm aluminum oxide polishing slurry in the polishing process.

[0055] The cleaning process involves cleaning with anhydrous ethanol followed by rinsing with deionized water.

[0056] 3) The high-entropy alloy substrate is placed in a tube furnace and heated at a rate of 8°C / min in an oxygen-containing atmosphere. After thermal oxidation treatment at 400°C for 3 hours, the substrate is allowed to cool naturally in the furnace to form an oxide layer on the surface of the high-entropy alloy substrate. The gas in the oxygen-containing atmosphere includes flowing air or pure oxygen.

[0057] 4) The high-entropy alloy substrate after step 3) is placed in a pit-type gas nitriding furnace. Under a high-purity nitrogen atmosphere, the temperature is increased at a rate of 8°C / min. After nitriding at 700°C for 3 hours, the substrate is allowed to cool naturally with the furnace. A nitriding layer is grown on the surface of the oxide layer to form a wear-resistant composite coating. The purity of the high-purity nitrogen gas is ≥99.99%.

[0058] Performance testing

[0059] 1. Surface hardness test

[0060] The microhardness of the product from Example 1 was tested, with an uncoated cast TiZrNbTaMo substrate used as a control group. The results are as follows: Figure 1 As shown.

[0061] from Figure 1 It can be seen that the Vickers hardness (HV) of the uncoated cast TiZrNbTaMo substrate is... 0.2 The Vickers hardness (HV) of the coated product of this invention is 334.0. 0.2 The surface hardness of the product of the present invention is 1348.4, indicating that the surface hardness is significantly improved.

[0062] 2. Wear rate and friction coefficient test

[0063] The product from Example 1 was used as a control group, with an uncoated cast TiZrNbTaMo substrate. Friction and wear tests were conducted on the samples using a reciprocating friction and wear testing machine. The wear rate and coefficient of friction were measured and calculated. The load was 10 N, the frequency was 2 Hz, and the friction pair was a zirconia ceramic ball with a diameter of 5 mm. The friction test was performed in PBS solution. The results are as follows: Figure 2-3 As shown.

[0064] from Figure 2 It can be seen that the wear rate of the product after nitriding is 7.9 × 10⁻⁶. -7 m 3 ·mm -1 ·N -1 Compared to as-cast high-entropy alloys, the wear rate is reduced by about two orders of magnitude, indicating that it has a lower wear rate than traditional alloys and exhibits excellent wear resistance.

[0065] from Figure 3 It can be seen that the friction coefficient of the product after oxidizing and nitriding is about 0.52, while that of the cast high-entropy alloy is about 0.70, a decrease of about 20%, which shows a good friction reduction effect.

[0066] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A method for preparing a high-entropy alloy wear-resistant composite coating, characterized in that, Includes the following steps: 1) The high-entropy alloy substrate is subjected to thermal oxidation treatment in an oxygen-containing atmosphere at a reaction temperature of 400-600℃ to form an oxide layer on the surface of the high-entropy alloy substrate; the high-entropy alloy substrate is a TiZrNbTaMo alloy. 2) The high-entropy alloy substrate after step 1) is placed in a high-purity nitrogen atmosphere for nitriding treatment. The reaction temperature is 700-1200℃ and the nitriding treatment time is 1-3h. A nitriding layer is grown on the surface of the oxide layer to form a wear-resistant composite coating. In step 1), the gas in the oxygen-containing atmosphere includes flowing air or pure oxygen; the thermal oxidation treatment time is 1 to 3 hours. In step 1), the heating rate of the thermal oxidation treatment apparatus is 8–12 °C / min; In step 2), the heating rate of the nitriding treatment device is 8-12 °C / min.

2. The method for preparing the high-entropy alloy wear-resistant composite coating as described in claim 1, characterized in that: In step 2), the purity of the high-purity nitrogen gas is ≥99.99%.

3. The method for preparing the high-entropy alloy wear-resistant composite coating as described in claim 1, characterized in that: In step 1), the apparatus for thermal oxidation treatment includes any one of a tube furnace, a pit-type gas nitriding furnace, or an atmosphere-protected muffle furnace; In step 2), the nitriding treatment apparatus includes any one of a pit-type gas nitriding furnace, a gas carburizing and nitriding furnace, and a tube furnace.

4. The method for preparing the high-entropy alloy wear-resistant composite coating as described in claim 1, characterized in that: Step 1) also includes the pretreatment of the high-entropy alloy substrate, wherein the pretreatment process includes grinding, polishing, cleaning and drying the high-entropy alloy substrate in sequence.

5. The method of claim 4, wherein the high-entropy alloy wear-resistant composite coating is prepared by the steps of: depositing a first layer of a high-entropy alloy on a substrate; and depositing a second layer of a high-entropy alloy on the first layer of the high-entropy alloy. The polishing process uses 100-5000 grit SiC sandpaper for polishing. The surface of the high-entropy alloy substrate is polished using 70-100nm silicon oxide polishing slurry and / or 40-60nm aluminum oxide polishing slurry. The cleaning process involves cleaning with anhydrous ethanol, followed by rinsing with deionized water and then drying.

6. The method of claim 1, wherein the high-entropy alloy wear-resistant composite coating is prepared by a process comprising: The high-entropy alloy matrix is ​​prepared by any one of the following methods: electric arc melting, induction melting, or vacuum suspension melting.

7. A high-entropy alloy wear-resistant composite coating, characterized in that: It is prepared by the method for preparing high-entropy alloy wear-resistant composite coating according to any one of claims 1-6.

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