Oxynitride coating with excellent wear resistance and mechanical properties, and preparation method and application thereof

Abstract

The application discloses an oxynitride coating with excellent wear resistance and mechanical property and a preparation method and application thereof, and is completed by using an arc ion plating-linear ion source combined coating machine; the oxynitride coating comprises a CrAlN transition layer, a CrAlSiN transition layer and a self-organizing nanometer multilayer CrAlSiON coating deposited on the surface of a substrate in sequence; when the CrAlSiON coating is deposited by using the arc ion plating technology, oxygen and nitrogen reaction gas is further ionized by using the linear ion source, the ionization rate of the gas is improved, the separation of the nanometer multilayer oxygen and nitrogen components is promoted, the nanometer multilayer interface is optimized, the mechanical property and the wear resistance of the coating are improved; in addition, the CrAlN transition layer and the CrAlSiN transition layer are additionally arranged between the substrate and the CrAlSiON coating, the bonding force between the CrAlSiON coating and the substrate is improved, and the coating with excellent comprehensive performance is prepared.

Description

Technical Field

[0001] This invention belongs to the field of coating materials technology, specifically relating to an oxynitride coating with excellent wear resistance and mechanical properties and its preparation method. Background Technology

[0002] In the machining of difficult-to-machine materials such as titanium alloys and hardened steel, the intense friction between the cutting tool surface and the chips and workpiece generates local cutting temperatures exceeding 1000℃. The wear mechanism of the coating also shifts from the abrasive wear of traditional machining to a coupled mechanism of high-temperature oxidation, adhesion, and diffusion wear, leading to rapid wear and failure of the coated tool. Therefore, coatings for high-speed machining of difficult-to-machine materials should possess high hardness, high thermal stability, and excellent wear resistance and friction reduction properties under high-temperature service environments. Traditional nitride coatings exhibit high hardness, toughness, wear resistance, and strong crack propagation resistance at room temperature, but their hardness decreases significantly at high temperatures and they are easily oxidized, increasing the wear rate. While oxide coatings possess good thermal and chemical stability, their mechanical properties, such as hardness and toughness, are relatively poor. How to combine the advantages of both nitride and oxide coatings to achieve excellent overall performance is a current research hotspot.

[0003] Incorporating a certain amount of oxygen into nitride coatings can improve coating performance. For example, doping TiAlN coatings with an appropriate amount of oxygen slightly reduces hardness but significantly improves high-temperature performance. Compared to TiAlN coatings, TiAlON coatings show significantly improved dry cutting performance. Based on the thermally stable AlCrN coating, AlCrON coatings were prepared using PVD technology. This coating exhibits significantly reduced friction coefficient and wear rate at high temperatures, demonstrating superior high-temperature tribological performance compared to AlCrN coatings. Compared to AlCrN coatings, the cutting life of cast iron and stainless steel is significantly improved. However, overall, high-nitrogen-content oxynitride coatings have a structure and properties similar to nitrides, but their high-temperature thermal stability and high-temperature tribological performance are inferior to oxide coatings. High-oxygen-content oxynitride coatings have a structure and properties similar to oxides, but their hardness and toughness are significantly lower than nitride coatings.

[0004] Studies have shown that by utilizing the differences in plasma energy and density, arc ion plating technology can deposit nano-multilayer oxynitride coatings with alternating nitrogen / oxygen contents in a mixed atmosphere of nitrogen and oxygen. These coatings combine the high mechanical properties of nitride coatings with the thermal and chemical stability of oxide coatings. However, in a mixed atmosphere, the ionization of reactant gases is limited, the separation of oxygen and nitrogen components is not significant, and the nano-multilayer interface is not sharp, hindering further improvement of coating performance. Furthermore, existing techniques for preparing nano-multilayer CrAlSiON coatings have a significant drawback: the adhesion between the CrAlSiON coating and the film is not adequately considered, resulting in insufficient bonding and limiting the application range of this material. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide an oxynitride coating with excellent wear resistance and mechanical properties, and its preparation method. The oxynitride coating comprises a CrAlN transition layer, a CrAlSiN transition layer, and a self-organized nano-multilayer CrAlSiON coating sequentially deposited on the substrate surface. In this invention, when depositing the CrAlSiON coating using arc ion plating technology, a linear ion source is used to further ionize the oxygen and nitrogen reaction gases, increasing the gas ionization rate, promoting the separation of oxygen and nitrogen components in the nano-multilayer, optimizing the nano-multilayer interface, and thus improving the mechanical properties and wear resistance of the coating. Furthermore, by adding the CrAlN transition layer and the CrAlSiN transition layer between the substrate and the CrAlSiON coating, the present invention improves the adhesion between the CrAlSiON coating and the substrate, resulting in an oxynitride coating with excellent overall performance.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing an oxynitride coating with excellent wear resistance and mechanical properties is disclosed. This method utilizes an arc ion plating-linear ion source composite coating machine. The target materials include Cr targets, Cr50Al50 alloy targets, and Cr40Al40Si20 alloy targets. The specific steps include:

[0008] S1. After polishing and cleaning, the substrate is placed in the vacuum chamber of the arc ion plating-linear ion source composite coating machine and evacuated to a vacuum level of 3×10⁻⁶. -3 Pa, and heated to 350-500℃, preferably 480℃; more preferably, the matrix is ​​cemented carbide or polycrystalline cubic boron nitride (PCBN) material, and the cemented carbide can be selected from products with grades such as YT15, YT14, YT5, YW1, YW10, YW2, etc. Those skilled in the art can select the corresponding specific grades as needed, and they are all applicable to the present invention;

[0009] S2. Introduce Ar gas and set a bias voltage of -600V to -800V on the substrate. Perform glow discharge cleaning on the substrate for 10 to 20 minutes. After glow discharge cleaning, set the rotation speed of the substrate during deposition to 1 to 5 r / min and turn on the Cr target to perform Cr metal ion etching pretreatment on the substrate for 8 to 15 minutes. Turn off the Ar gas and turn on N2. Then turn on the Cr50Al50 alloy target and the Cr40Al40Si20 alloy target in sequence to deposit the CrAlN transition layer and the CrAlSiN transition layer in sequence on the substrate surface. Preferably, the deposition time of the CrAlN transition layer is 5 to 10 minutes and the deposition time of the CrAlSiN transition layer is 10 to 15 minutes.

[0010] S3. Finally, turn on the ion source and set the power of the ion source to 1-3kW. Introduce a mixture of nitrogen and oxygen into the vacuum chamber. The flow rates of nitrogen and oxygen in the mixture are 400-600 sccm and 10-100 sccm, respectively. Deposit a self-organized nano-multilayer CrAlSiON coating for 60-120 minutes to finally obtain an oxynitride coating with excellent wear resistance and mechanical properties.

[0011] The oxynitride coating prepared by the above method includes a CrAlN transition layer, a CrAlSiN transition layer, and a self-organized nano-multilayer CrAlSiON coating deposited sequentially on the substrate surface from bottom to top. The self-organized nano-multilayer CrAlSiON coating is formed by alternating deposition of nitrogen-rich and oxygen-rich layers. The mass percentage of Cr atoms in the self-organized nano-multilayer CrAlSiON coating is 22.1–23.4 at.%, the mass percentage of Al atoms is 17.3–19.5 at.%, the mass percentage of Si atoms is 6.9–7.8 at.%, the mass percentage of O atoms is 0–8.8 at.%, and the mass percentage of N atoms is 42–53.4 at.%.

[0012] The present invention has the following beneficial effects:

[0013] (1) In the deposition process of self-organized nano-multilayer CrAlSiON coating, the present invention improves the ionization rate of the reactive gas by linear ion source assisted deposition, and the reaction between the metal particles sputtered from the target and the reactive gas is more complete, which improves the modulation period of the nano-multilayer and the thickness of the oxygen-rich layer. The presence of the oxygen-rich layer interrupts the columnar growth trend of nitrides and forms a finer grain structure. The combined effect of fine grain strengthening and nano-multilayer strengthening further improves the excellent performance of nitrogen oxides. The room temperature hardness and high temperature wear resistance of the coating are significantly improved, which has a significant benefit effect on improving the surface wear protection efficiency of the coating.

[0014] (2) Considering the large differences in lattice constant and thermal expansion coefficient between the CrAlSiON coating and the substrate, which may lead to insufficient adhesion between the coating and the substrate, this invention adds a CrAlN transition layer and a CrAlSiN transition layer between the substrate and the CrAlSiON coating. Since the composition and lattice constant of the CrAlN transition layer and the CrAlSiN transition layer are similar to those of the CrAlSiON coating, and the residual stress and other properties of the CrAlSiON coating are improved, a compositional gradient transition can be achieved, which can effectively reduce the mismatch at the film-substrate interface and improve the coating adhesion.

[0015] (3) The preparation method of the present invention is simple, easy to operate and easy to control. It is suitable for the protection of the surface of mechanical parts, cutting tools, molding dies and other products, and has good economic benefits. Attached Figure Description

[0016] Figure 1 SEM and TEM images of the oxynitride coating prepared in Example 1.

[0017] Figure 2 The images show the characterization of the CrAlSiON coating in the product prepared in Example 1, where a is a TEM image; b is a HADDF image; and c is an EDS surface scan of different elements.

[0018] Figure 3 The room temperature hardness diagrams are for the products prepared in Example 1, Comparative Example 1, and Comparative Example 2.

[0019] Figure 4 The wear rate diagrams for the products prepared in Example 1, Comparative Example 1, and Comparative Example 2 at 800°C are shown.

[0020] Figure 5 These are cross-sectional SEM images of the products prepared in Example 1(a), Comparative Example 1(b), Comparative Example 2(c), and Comparative Example 3(d).

[0021] Figure 6 This is a comparison diagram of the scratch adhesion of the products prepared in Example 1 and Comparative Example 3. Detailed Implementation

[0022] The present invention will be further described below with reference to embodiments, so that those skilled in the art can better understand and implement the present invention, but the embodiments are not intended to limit the present invention.

[0023] In addition, unless otherwise specified, the preparation processes in the following embodiments are all conventional methods in the prior art, and therefore will not be described in detail.

[0024] Example 1

[0025] The equipment used is an arc ion plating-linear ion source composite coating machine. Specifically, the device disclosed in patent CN103668095B can be used for experiments. The target materials used include Cr target (purity 99.8%, Φ160mm), Cr50Al50 alloy target (purity 99.8%, Φ160mm) and Cr40Al40Si20 alloy target (purity 99.8%, Φ160mm).

[0026] A method for preparing an oxynitride coating with excellent wear resistance and mechanical properties includes the following steps:

[0027] Select cemented carbide block YT15 (15×15×4mm) 3 The substrate was used as a base material and polished. The polishing machine speed was set to 300 rpm, and 1000-grit and 2000-grit diamond grinding discs were used to polish the substrate until the surface was free of obvious scratches. Then, metallographic polishing cloth and polishing fluid were used to polish the substrate until a mirror finish was achieved. Subsequently, the substrate was ultrasonically cleaned with metal cleaning fluid and acetone for 20 minutes each. After cleaning, the substrate was dried with a cotton swab dipped in acetone. Then, anhydrous ethanol was used for ultrasonic cleaning for 20 minutes. After cleaning, the substrate was dried with a cotton swab dipped in anhydrous ethanol. The substrate was then clamped in a vacuum chamber. Before deposition, the furnace chamber was heated to 480℃, and the background vacuum was evacuated to 3×10⁻⁶. - 3 Pa. To remove contaminants from the substrate surface, the substrate was glow-cleaned for 20 min with Ar gas at a bias voltage of -800V and a flow rate of 350 sccm. After glow-cleaning, the substrate rotation speed was set to 2.5 r / min during deposition, and the Cr target was turned on to bombard the substrate with high-energy metal ions for 8 min. The Ar gas was then turned off, and N2 was turned on at a flow rate of 500 sccm. The Cr50Al50 target and the Cr40Al40Si20 target were turned on sequentially to deposit a CrAlN transition layer for 5 min, followed by a CrAlSiN transition layer for 10 min. Finally, the ion source was turned on, the ion source power was set to 1kW, the flow rate of nitrogen and oxygen was controlled to be 450sccm and 10sccm respectively, the chamber pressure was adjusted to 3.5Pa, and a nano-multilayer CrAlSiON coating was deposited for 90min. The atomic percentage content of the obtained CrAlSiON coating was Cr: 22.5at.%, Al: 18.1at.%, Si: 7.2at.%, O: 7.7at.%, N: 44.5at.%. After the deposition was completed, an oxynitride coating was obtained on the substrate surface.

[0028] Comparative Example 1

[0029] Compared with Example 1, the difference in Comparative Example 1 is that: in the final deposition of the nano-multilayer CrAlSiON coating, the ion source was not turned on and no oxygen was introduced. The coating formed on the outermost surface of the substrate was a CrAlSi coating with the following atomic percentages: Cr: 22.3 at.%, Al: 18.4 at.%, Si: 7.3 at.%, N: 52.0 at.%. All other processes were the same as in Example 1.

[0030] Comparative Example 2

[0031] Compared with Example 1, the difference in Comparative Example 2 is that no ion source was turned on when depositing the self-organized nano-multilayer CrAlSiON coating. The atomic percentage content of the obtained CrAlSiON coating is Cr: 22.1 at.%, Al: 17.9 at.%, Si: 7.3 at.%, O: 7.2 at.%, N: 45.5 at.%, and the other processes are the same as in Example 1.

[0032] Comparative Example 3

[0033] Compared with Example 1, the difference in Comparative Example 3 is that the steps related to depositing the CrAlN transition layer and the CrAlSiN transition layer are omitted, and a self-organized nano-multilayer CrAlSiON coating is directly deposited on the surface of the substrate.

[0034] The products prepared in Example 1 and Comparative Examples 1 to 3 were characterized structurally and tested for performance. The results are as follows:

[0035] Figure 1 These are SEM images (b) of the overall oxynitride coating prepared in Example 1 and TEM (a) of the CrAlSiON coating. Figure 1 It can be seen that the nano-multilayer CrAlSiON coating prepared by the method provided in this invention is a nano-multilayer coating with alternating nitrogen / oxygen contents.

[0036] Figure 2 The image shows the characterization of the CrAlSiON coating in the product prepared in Example 1, combined with... Figure 2Figures a and c show that the CrAlSiON coating prepared under the N2 / O2 flow ratio of 450 / 10 in Example 1 formed a distinct nano-multilayer structure with alternating nitrogen / oxygen contents. The modulation period of the nano-multilayer was approximately 15.2 nm, with the oxygen-rich layer having a thickness of approximately 1.9 nm. In contrast, the modulation period and oxygen-rich layer thickness without an ion source were 12.9 nm and 1.4 nm, respectively. This indicates that ion source-assisted deposition improved both the modulation period and the oxygen-rich layer thickness. This is mainly because the ion source increased the ionization rate of the reactive gas, leading to a more complete reaction between the sputtered metal particles and the reactive gas. Furthermore, in HAADF mode, the interface between the N-rich and O-rich layers was found to be sharper compared to the case without an ion source. Figure 2 As shown in (b).

[0037] Figure 3 These are room temperature hardness diagrams of the products prepared in Example 1, Comparative Example 1, and Comparative Example 2. It can be seen that the coating hardness of Example 1 is increased by using ion source-assisted deposition. The increase in hardness is mainly due to the fact that some O atoms replace N atoms, causing lattice distortion. In addition, as can be seen from the TEM results, after doping with oxygen, a nano-multilayer structure of alternating nitrogen-rich and oxygen-rich layers is formed, which improves the coating's ability to hinder the movement of lattice dislocations.

[0038] Figure 4 This is a wear rate graph showing the products prepared in Example 1, Comparative Example 1, and Comparative Example 2 at 800°C. It can be seen that, compared to Comparative Example 1 and Comparative Example 2, the wear rate of the product prepared in Example 1 is significantly reduced, with a wear rate of 6 × 10⁻⁷ mm at 800°C. 3 / Nm, which is closely related to the coating's hardness, toughness, and film-substrate adhesion. Ion-assisted deposition coatings exhibit increased hardness due to lattice distortion and nano-multilayer reinforcement effects, thereby reducing the wear rate. Furthermore, oxygen doping pre-forms protective Al2O3 and lubricating Cr2O3 in the coating, which also contributes to improved wear resistance.

[0039] Figure 5 These are cross-sectional SEM images of the products prepared in Examples 1(a), 1(b), 2(c), and 3(d). It can be seen that the coatings prepared in these examples have a denser structure. This is because ion-assisted deposition increases the ionization rate of the reactive gases, allowing for a more complete reaction between the reactive gases and the metal particles. Oxygen has a higher reactivity than nitrogen, thus resulting in a denser coating cross-section.

[0040] Figure 6The image shows a comparison of the scratch adhesion of the products prepared in Example 1 and Comparative Example 3. It can be seen that the coating prepared in Example 1 has a higher adhesion to the substrate than that in Comparative Example 3. The adhesion of Example 1 is 70.5 N, while that of Comparative Example 3 is 35.6 N.

[0041] It should be noted that in other embodiments, the objective of this invention can be achieved when the preparation process meets the following conditions:

[0042] For the bias voltage set on the substrate, the preferred bias voltage is -600V to -800V, specifically -600V, -700V, or -800V, etc.

[0043] The preferred revolution rate of the matrix is ​​1 to 5 r / min, specifically 1 r / min, 2 r / min, 3 r / min, 4 r / min or 5 r / min, etc.

[0044] The preferred time for glow discharge cleaning is 10 to 20 minutes, specifically 10 minutes, 15 minutes, or 20 minutes, etc.

[0045] The preferred time for Cr metal ion etching pretreatment is 8 to 15 minutes, specifically 8 minutes, 12 minutes, or 15 minutes, etc.

[0046] The preferred time for depositing the CrAlN transition layer is 5 to 10 minutes, specifically 5 minutes, 8 minutes, or 10 minutes; the preferred time for depositing the CrAlSiN transition layer is 10 to 15 minutes, specifically 10 minutes, 12 minutes, or 15 minutes.

[0047] The power of the ion source is preferably 1 to 3 kW, specifically 1 kW, 2 kW or 3 kW, etc.

[0048] For the nitrogen and oxygen flow rates in the nitrogen-oxygen mixture, the preferred flow rates are 400–600 sccm and 10–100 sccm, respectively; as long as the flow rates are within this range, it is acceptable.

[0049] The preferred deposition time for the self-organized nano-multilayer CrAlSiON coating is 60–120 min, specifically 60 min, 80 min, 100 min, or 120 min.

[0050] Those skilled in the art can make appropriate selections of the above process parameters according to actual needs, and all of them can achieve the purpose of this invention.

[0051] Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A method for preparing an oxynitride coating with excellent wear resistance and mechanical properties, characterized in that: It is completed using an arc ion plating-linear ion source composite coating machine. The target materials include Cr target, Cr50Al50 alloy target and Cr40Al40Si20 alloy target. The specific steps include: S1. After polishing and cleaning, the substrate is placed in the vacuum chamber of the arc ion plating-linear ion source composite coating machine, evacuated and heated to 350-500℃. S2. Introduce Ar gas and set a bias voltage of -600V to -800V on the substrate to perform glow discharge cleaning. After glow discharge cleaning, set the rotation speed of the substrate during deposition to 1 to 5 r / min and turn on the Cr target to perform Cr metal ion etching pretreatment on the substrate. Turn off Ar gas and turn on N2. Then turn on the Cr50Al50 alloy target and the Cr40Al40Si20 alloy target in sequence to deposit the CrAlN transition layer and the CrAlSiN transition layer on the substrate surface in sequence. S3. Finally, turn on the ion source and introduce a mixture of nitrogen and oxygen into the vacuum chamber to deposit a self-organized nano-multilayer CrAlSiON coating, ultimately obtaining an oxynitride coating with excellent wear resistance and mechanical properties. The power of the ion source is 1~3 kW, and the nitrogen flow rate and oxygen flow rate in the nitrogen and oxygen mixture are 400~600 sccm and 10~100 sccm, respectively. The deposition time for the self-organized nano-multilayer CrAlSiON coating is 60~120 min; The self-organized nano-multilayer CrAlSiON coating is formed by alternating deposition of nitrogen-rich and oxygen-rich layers.

2. The preparation method according to claim 1, characterized in that: The substrate is a hard alloy or a polycrystalline cubic boron nitride material.

3. The preparation method according to claim 1, characterized in that: The glow discharge cleaning time is 10-20 min, and the Cr metal ion etching pretreatment time is 8-15 min.

4. The preparation method according to claim 1, characterized in that: The deposition time for the CrAlN transition layer is 5-10 min, and the deposition time for the CrAlSiN transition layer is 10-15 min.

5. An oxynitride coating with excellent wear resistance and mechanical properties, characterized in that: It is prepared by the preparation method according to any one of claims 1 to 4; the oxynitride coating comprises a CrAlN transition layer, a CrAlSiN transition layer and a self-organized nano-multilayer CrAlSiON coating deposited sequentially on the substrate surface from bottom to top; the self-organized nano-multilayer CrAlSiON coating has a Cr atom mass percentage of 22.1~23.4 at.%, an Al atom mass percentage of 17.3~19.5 at.%, a Si atom mass percentage of 6.9~7.8 at.%, an O atom mass percentage of 0~8.8 at.%, and a N atom mass percentage of 42~53.4 at.%.

6. The application of the oxynitride coating as described in claim 5 in the fields of mechanical parts, cutting tools, and molding dies.

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