High-heat-resistance composite multilayer coating and preparation method thereof

Abstract

The invention provides a high-heat-resistance composite multilayer coating and a preparation method thereof, and particularly relates to the technical field of surface coatings. The invention discloses a high-heat-resistance composite multilayer coating. The high-heat-resistance composite multilayer coating comprises a Cr bonding layer, a Cr < 1-X > Al < X > N / nc-CrAl < N-a-CNX multilayer transition layer and an nc-CrAl < N-a-CNX functional layer which are sequentially coated on a hard alloy matrix. According to the Cr1-XAlXN / nc-CrAlN-a-CNX multi-layer transition layer and the nc-CrAlN-a-CNX functional layer provided by the invention, the enhancement characteristics of Cr1-XAlXN and CNX are effectively combined, and the composite multi-layer structure is endowed with excellent wear resistance, so that good lubrication and wear resistance in a high-temperature environment are realized, the high heat resistance of the amorphous carbon-nitrogen layer is remarkably expanded, and the service life of the amorphous carbon-nitrogen layer is prolonged. Meanwhile, due to the transition of the content of CrAl and C in components and a multi-layer supporting layer construction method, the film-substrate binding force between a substrate and a plating layer is effectively improved, the toughness and the bearing capacity of a top coating are enhanced, the internal stress of a functional layer amorphous carbon-like layer is relieved, the friction coefficient and the wear rate of the amorphous carbon-based solid lubricating coating are remarkably reduced, and the service life of the amorphous carbon-based solid lubricating coating is prolonged. And the comprehensive wear resistance is greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of surface coatings, and in particular to a high heat-resistant composite multi-layer coating and a preparation method thereof. Background Art

[0002] The piston ring is a core component inside a fuel engine. It works together with the cylinder, piston, cylinder wall, etc. to seal the fuel gas. With the complexity of service conditions, the wear failure and scrapping of piston rings due to poor thermal stability under high temperature conditions are increasing day by day. How to prepare a coating with high heat resistance on the surface of the piston ring is a difficult problem that the automotive industry urgently needs to solve.

[0003] Solving the friction and wear problems on the surface of mechanical parts used under harsh conditions such as high temperature and high speed of piston rings is of great significance to the development of the automotive industry. At present, compared with developed industrial countries, my country still has a large gap in the manufacturing of precision, complex and long-life parts, mainly in the research and application of new material surface engineering technology. At present, many piston parts in my country still basically use traditional surface engineering technologies such as chemical heat treatment, thermal spraying and electroplating. In particular, there is less research, development and application of new material systems, which seriously restricts the improvement of the performance of weapon parts. Research, development and preparation of nano multi-layer composite films with high heat resistance, low friction coefficient and high bonding strength with the matrix are expected to reduce the energy consumption of piston ring transmission systems, extend the service life of parts and components, and improve the reliability and economy of automobile braking systems.

[0004] Composite metal nitrides have the characteristics of high hardness and high wear resistance. CrAlN, CrAlSiN and other coatings have received attention from researchers. Compared with traditional TiN, TiCN and TiAlN, composite metal nitride coatings have higher red hardness and oxidation resistance, and the use temperature can reach 800℃. This coating process is suitable for high-speed brake system running parts. The CrAlSiN composite coating is formed by adding Si elements to improve the overall high-temperature oxidation resistance of the coating, but the improvement of the self-lubricating performance of the composite film layer is limited. The nano-multilayer film Cr1-XAlXN / (nc-CrAlN-a-CNX) composed of composite metal nitrides and nitride systems with nanocrystalline and amorphous composite structure characteristics has good high-temperature oxidation resistance and comprehensive mechanical properties. Studies have shown that: the composite nitride film has high bonding strength with the metal substrate; the nanocrystalline lattice in the nanocrystalline and amorphous composite film is incomplete, and will not produce a large lattice mismatch energy under external conditions, which improves the film bonding strength; and the amorphous matrix is ​​easy to adapt to and match with other organizational structures.

[0005] At present, there are still few reports on nano-multilayer carbon-nitrogen-based coatings suitable for harsh working conditions in the high temperature domain (800°C). Therefore, overcoming the poor thermal stability of carbon-nitrogen-based composite coatings and refining the particle size of the doped phase in the coatings are of great significance for further expanding their application fields. Summary of the invention

[0006] In view of the above-mentioned shortcomings of the prior art, the present invention provides a method for preparing a high heat-resistant composite multi-layer coating, which can effectively solve the problems mentioned in the prior art.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0008] The invention provides a high heat-resistant composite multilayer coating, which comprises a Cr bonding layer, a Cr 1-X Al X N / nc-CrAlN-a-CN X Multilayer transition layer and nc-CrAlN-a-CN X Functional layer composition.

[0009] Preferably, the Cr 1-X Al X N / nc-CrAlN-a-CN X The multi-layer transition layer is formed by depositing a cross-ionized graphite target and a CrAl composite target on the Cr bonding layer in a nitrogen atmosphere.

[0010] Preferably, the Cr 1-X Al X N / nc-CrAlN-a-CN X The thickness of the multi-layer transition layer is 15-25nm; the nc-CrAlN-a-CN X The CrAl content in the functional layer gradually decreases in a direction away from the substrate, the C content gradually increases in a direction away from the substrate, and the N content is 32% to 35%.

[0011] A method for preparing a high heat-resistant composite multilayer coating comprises the following steps:

[0012] Pretreatment steps: clean the carbide piston ring base material in an ultrasonic cleaner with anhydrous ethanol for 10 minutes, then clean the base material in an ultrasonic cleaner with acetone for 10 minutes, and dry;

[0013] Vacuum and cleaning steps: Clamp the piston ring substrate and Cr target, CrAl target and high-purity graphite target, turn on the cooling water, and start the machine to vacuum to 2.0×10 -4Pa, introduce argon gas into the vacuum chamber, turn on the ion source to clean the substrate for 20 minutes, and at the same time raise the temperature to 200-300°C and bake for 0.5-2 hours;

[0014] Preparation steps of Cr bonding layer: turn off the ion source, turn off the argon gas, and evacuate to 1.0×10 -3 -3.0×10 -3 Pa, set the Cr target arc current to 50-60A, the negative bias voltage to 750-850V, the filter current to 10-14A, and the deposition time to 15-25min to obtain a Cr bonding layer;

[0015] Cr 1-X Al X N / nc-CrAlN-a-CN X Preparation steps of multilayer transition layer: turn off the Cr target, turn on the CrAl and graphite targets, introduce nitrogen, and keep the indoor pressure at 1.0×10 -2 -3.0×10 -2 Pa, set the CrAl target arc current to 70-80A, the negative bias voltage to 900-1000V, and the graphite target arc current to 50-60A, the negative bias voltage to 700-800V, and the cross deposition time to 20-40s, respectively, to obtain Cr 1-X Al X N / nc-CrAlN-a-CN X Multiple transition layers;

[0016] nc-CrAlN-a-CN X Functional layer preparation steps: gradually reduce the CrAl target arc current, and gradually increase the graphite target arc current to 80-90A, reduce the temperature to 100-120℃, and keep the indoor pressure at 1.0×10 -2 -3.0×10 -2 Pa, negative bias voltage is 500-650V, rotating substrate keeps CrAl target and graphite target co-deposited, and nc-CrAlN-a-CN is obtained. X Functional layer;

[0017] Post-processing steps: Turn off the target and keep the pressure in the vacuum chamber at 1.0×10 -2 -3.0×10 -2 Pa, while maintaining the temperature at 100-120°C for 2-4 hours, and then taking it out of the furnace after cooling to 50-60°C.

[0018] Preferably, the surface of the treated cemented carbide piston ring contains Cr 1-X Al X N / nc-CrAlN-a-CN X High sp of multi-layer transition layer 3The thickness of the chromium bonding layer in the carbon-nitrogen film is 150-250nm; the thickness of the multilayer transition layer Cr1-XAlXN single layer is 15-30nm, and the thickness of the nc-CrAlN-a-CN X The functional layer is 500nm, and the sp 3 The bond content is 45%-58%, and the mass fractions of Cr and Al in the coating are 15.5%-17.5% and 16.9%-18.2% respectively.

[0019] Compared with the known prior art, the technical solution provided by the present invention has the following beneficial effects:

[0020] (1) Compared with the traditional CrN coating, the ternary Cr-Al-N coating formed by adding Al in the present invention has greatly improved performance in terms of resistance to abrasive wear and high-temperature oxidation. The CrAlN coating formed after adding Al has high hardness and good high-temperature lubricity, so the friction and wear characteristics and the load bearing capacity of the coating under high load conditions are significantly improved.

[0021] (2) The hardness of the CrAlN coating remains at 27 GPa at 1000°C, which is currently the optimal hardness value of nitride at this temperature. Cr is the main element for improving thermal corrosion resistance, and Al can promote the formation of a stable Al2O3 film. Therefore, the CrAlN coating has both good corrosion resistance and high-temperature oxidation resistance.

[0022] (3) The process of the present invention is designed from two dimensions: component optimization and multilayer structure enhancement. The Cr 1-X Al X N / nc-CrAlN-a-CN X Multilayer transition layer and nc-CrAlN-a-CN X The functional layer not only effectively combines Cr 1- X Al X N and CN X The composite multilayer structure gives it excellent wear resistance, thereby achieving good lubrication and wear resistance in high temperature environments, significantly expanding the high heat resistance of the amorphous carbon-nitrogen layer. At the same time, the transition of CrAl and C content in the components and the multilayer support layer construction method effectively improve the film-based bonding between the substrate and the coating, enhance the toughness and bearing capacity of the top coating, and relieve the internal stress of the functional layer-like amorphous carbon layer. It plays a role in buffering stress and preventing the initiation of interface cracks during friction, which significantly reduces the friction coefficient and wear rate of the amorphous carbon-based solid lubrication coating, and greatly improves the comprehensive wear performance.

[0023] (4) The high heat-resistant composite metal nitride / amorphous carbon-nitrogen composite multilayer coating of the present invention realizes the coordinated unification of the coating structure and function on the surface of the substrate such as the piston ring moving base parts, effectively improves the comprehensive performance and service life of the coating and the substrate, and can meet the urgent demand for wear-resistant coatings in high-temperature environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0025] Figure 1 Schematic diagram of the coating layer of the coating in Example 1 of the present invention. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the 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.

[0027] The present invention will be further described below in conjunction with the embodiments.

[0028] Embodiment 1:

[0029] Reference Figure 1 This embodiment discloses a method for preparing a high heat-resistant composite multilayer coating, which uses a high-power pulse power supply magnetron sputtering technology to deposit a metal nitride / amorphous carbon-nitrogen composite multilayer coating on the surface of a pretreated substrate. The metal nitride / amorphous carbon-nitrogen composite multilayer coating includes a Cr bonding layer and a Cr 1-X Al X N / nc-CrAlN-a-CN X Multilayer transition layer and nc-CrAlN-a-CN X Functional layer, Cr 1-X Al X N / nc-CrAlN-a-CN X The multilayer transition layer is deposited on the Cr bonding layer by cross-ionizing graphite target and CrAl composite target in nitrogen atmosphere. 1-X Al X N layer and nc-CrAlN-a-CN XThe layer thickness is controlled in the range of 15-25 nanometers.

[0030] Furthermore, the matrix includes a cemented carbide matrix, and along the direction gradually away from the matrix, nc-CrAlN-a-CN X The CrAl content in the functional layer is decreasing, the C content is increasing, and the N content is maintained in a range of 32% to 35%, comprising the following steps:

[0031] Step 1, pre-treating the cemented carbide piston ring substrate, cleaning the substrate material in an ultrasonic cleaning machine with anhydrous ethanol for 10 minutes, then cleaning the substrate material in an ultrasonic cleaning machine with acetone for 10 minutes, and then drying;

[0032] Step 2: Clamp the carbide piston ring substrate, Cr target, CrAl target and high-purity graphite target, turn on the cooling water, and start the machine to evacuate to 2.0×10 -4 Pa, introduce argon gas into the vacuum chamber, turn on the ion source to clean the substrate for 15 min, and at the same time raise the temperature to 200 °C and bake for 1 h;

[0033] Step 3: Turn off the ion source, turn off the argon gas, and evacuate to 2.0×10 -3 Pa, set the Cr target arc current to 50A, the negative bias voltage to 800V, the filter current to 10A, and the deposition time to 20min to obtain a pure Cr bonding layer; turn off the Cr target, turn on the CrAl target and the graphite target, introduce nitrogen, and keep the indoor pressure at 2.0×10 -2 Pa, set the CrAl target arc current to 70A, the negative bias voltage to 1000V, and set the graphite target arc current to 50V, the negative bias voltage to 700V, and perform cross deposition for 20s respectively to obtain Cr 1- X Al X N / nc-CrAlN-a-CN X Multiple transition layers;

[0034] Step 4: Then gradually reduce the CrAl target arc current, and gradually increase the graphite target arc current to 80A, reduce the temperature to 120°C, and maintain the indoor pressure at 2.0×10 -2 Pa, set the negative bias voltage to 500 V, rotate the substrate to keep the CrAl target and the graphite target co-deposited, and keep nc-CrAlN-a-CN X functional layer; then the target is closed and the pressure in the vacuum chamber is maintained at 2.0×10 - 2 Pa, while maintaining the temperature at 120°C for 3 hours, and then taking it out of the furnace after cooling to 50°C.

[0035] It has been determined that the surface of the piston ring contains Cr 1-X AlX N / nc-CrAlN-a-CN X High sp of multi-layer transition layer 3 The thickness of the chromium bonding layer in the carbon-nitrogen film is 150nm; the thickness of the multilayer transition layer Cr1-XAlXN single layer is 15nm, and the thickness of the nc-CrAlN-a-CN X The functional layer is 500nm, and the sp 3 The bond content is 58%, and the mass fractions of Cr and Al in the coating are 15.5% and 17.2%.

[0036] Embodiment 2:

[0037] Step 1, pre-treating the cemented carbide piston ring substrate, cleaning the substrate material in an ultrasonic cleaning machine with anhydrous ethanol for 10 minutes, then cleaning the substrate material in an ultrasonic cleaning machine with acetone for 10 minutes, and then drying;

[0038] Step 2: Clamp the carbide piston ring substrate, Cr target, CrAl target and high-purity graphite target, turn on the cooling water, and start the machine to evacuate to 2.0×10 -4 Pa, introduce argon gas into the vacuum chamber, turn on the ion source to clean the substrate for 25 minutes, and at the same time raise the temperature to 250°C and bake for 0.5 hours;

[0039] Step 3: Turn off the ion source, turn off the argon gas, and evacuate to 3.0×10 -3 Pa, set the Cr target arc current to 55A, the negative bias voltage to 850V, the filter current to 12A, and the deposition time to 25min to obtain a pure Cr bonding layer; turn off the Cr target, turn on the CrAl target and the graphite target, introduce nitrogen, and keep the indoor pressure at 3.0×10 -2 Pa, set the CrAl target arc current to 80A, the negative bias voltage to 900V, and the graphite target arc current to 55V, the negative bias voltage to 750V, and perform cross deposition for 30s respectively to obtain Cr 1- X Al X N / nc-CrAlN-a-CN X Multiple transition layers;

[0040] Step 4: Then gradually reduce the CrAl target arc current, and gradually increase the graphite target arc current to 85A, reduce the temperature to 110°C, and maintain the indoor pressure at 3.0×10 -2 Pa, set the negative bias voltage to 550 V, rotate the substrate to keep the CrAl target and the graphite target co-deposited, and keep nc-CrAlN-a-CN X functional layer; then the target is closed and the pressure in the vacuum chamber is maintained at 3.0×10 - 2Pa, while maintaining the temperature at 110°C for 4 hours, and then taking it out of the furnace after cooling to 60°C.

[0041] It has been determined that the surface of the piston ring contains Cr 1-X Al X N / nc-CrAlN-a-CN X High sp of multi-layer transition layer 3 The thickness of the chromium bonding layer in the carbon-nitrogen film is 250nm; the multi-layer transition layer Cr 1-X Al X The thickness of N single layer is 20nm, nc-CrAlN-a-CN X The functional layer is 500nm, and the sp 3 The bond content is 50%, and the mass fractions of Cr and Al in the coating are 16.1% and 16.9%.

[0042] Embodiment 3:

[0043] Step 1, pre-treating the cemented carbide piston ring substrate, cleaning the substrate material in an ultrasonic cleaning machine with anhydrous ethanol for 10 minutes, then cleaning the substrate material in an ultrasonic cleaning machine with acetone for 10 minutes, and then drying;

[0044] Step 2: Clamp the carbide piston ring substrate, Cr target, CrAl target and high-purity graphite target, turn on the cooling water, and start the machine to evacuate to 2.0×10 -4 Pa, introduce argon gas into the vacuum chamber, turn on the ion source to clean the substrate for 20 min, and at the same time raise the temperature to 300 °C and bake for 2 h;

[0045] Step 3: Turn off the ion source, turn off the argon gas, and evacuate to 2.0×10 -3 Pa, set the Cr target arc current to 60A, the negative bias voltage to 750V, the filter current to 14A, and the deposition time to 15min to obtain a pure Cr bonding layer; turn off the Cr target, turn on the CrAl target and the graphite target, introduce nitrogen, and keep the indoor pressure at 1.0×10 -2 Pa, set the CrAl target arc current to 75A, the negative bias voltage to 950V, and the graphite target arc current to 60V, the negative bias voltage to 800V, and perform cross deposition for 40s respectively to obtain Cr 1-X Al X N / nc-CrAlN-a-CN X Multiple transition layers;

[0046] Step 4: Then gradually reduce the CrAl target arc current, and gradually increase the graphite target arc current to 80A, reduce the temperature to 100°C, and maintain the indoor pressure at 1.0×10 -2Pa, set the negative bias voltage to 650 V, rotate the substrate to keep the CrAl target and the graphite target co-deposited, and keep nc-CrAlN-a-CN X functional layer; then the target is closed and the pressure in the vacuum chamber is maintained at 1.0×10 - 2 Pa, while maintaining the temperature at 100°C for 2h, and then taking it out of the furnace after cooling to 60°C.

[0047] It has been determined that the surface of the piston ring contains Cr 1-X Al X N / nc-CrAlN-a-CN X High sp of multi-layer transition layer 3 The thickness of the chromium bonding layer in the carbon-nitrogen film is 15nm; the thickness of the multilayer transition layer Cr1-XAlXN single layer is 30nm, and the thickness of nc-CrAlN-a-CN X The functional layer is 500nm, and the sp 3 The bond content is 45%, and the mass fractions of Cr and Al in the coating are 17.5% and 18.2%.

[0048] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements will not cause the essence of the corresponding technical solutions to deviate from the protection scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high heat-resistant composite multi-layer coating, characterized in that: The Cr bonding layer, Cr 1-X Al X N / nc-CrAlN-a-CN X Multilayer transition layer and nc-CrAlN-a-CN X Functional layer composition.

2. A high heat-resistant composite multi-layer coating according to claim 1, characterized in that: The Cr 1-X Al X N / nc-CrAlN-a-CN X The multi-layer transition layer is formed by depositing a cross-ionized graphite target and a CrAl composite target on the Cr bonding layer in a nitrogen atmosphere.

3. The high heat-resistant composite multi-layer coating according to claim 1, characterized in that: The Cr 1-X Al X N / nc-CrAlN-a-CN X The thickness of the multi-layer transition layer is 15-25nm; The nc-CrAlN-a-CN X The CrAl content in the functional layer gradually decreases in a direction away from the substrate, the C content gradually increases in a direction away from the substrate, and the N content is 32% to 35%.

4. A method for preparing the high heat-resistant composite multi-layer coating according to any one of claims 1 to 3, characterized in that: The following steps are involved: Pretreatment steps: clean the carbide piston ring base material in an ultrasonic cleaner with anhydrous ethanol for 10 minutes, then clean the base material in an ultrasonic cleaner with acetone for 10 minutes, and dry; Vacuum and cleaning steps: Clamp the piston ring substrate and Cr target, CrAl target and high-purity graphite target, turn on the cooling water, and start the machine to vacuum to 2.0×10 −4 Pa, introduce argon gas into the vacuum chamber, turn on the ion source to clean the substrate for 20 minutes, and at the same time raise the temperature to 200-300°C and bake for 0.5-2 hours; Preparation steps of Cr bonding layer: turn off the ion source, turn off the argon gas, and evacuate to 1.0×10 −3 -3.0×10 −3 Pa, set the Cr target arc current to 50-60A, the negative bias voltage to 750-850V, the filter current to 10-14A, and the deposition time to 15-25min to obtain a Cr bonding layer; Cr 1-X Al X N / nc-CrAlN-a-CN X Preparation steps of multilayer transition layer: turn off the Cr target, turn on the CrAl and graphite targets, introduce nitrogen, and keep the indoor pressure at 1.0×10 −2 -3.0×10 −2 Pa, set the CrAl target arc current to 70-80A, the negative bias voltage to 900-1000V, and the graphite target arc current to 50-60A, the negative bias voltage to 700-800V, and the cross deposition time to 20-40s, respectively, to obtain Cr 1-X Al X N / nc-CrAlN-a-CN X Multiple transition layers; nc-CrAlN-a-CN X Functional layer preparation steps: gradually reduce the CrAl target arc current, and gradually increase the graphite target arc current to 80-90A, reduce the temperature to 100-120℃, and keep the indoor pressure at 1.0×10 −2 -3.0×10 −2 Pa, negative bias voltage is 500-650V, rotating substrate keeps CrAl target and graphite target co-deposited, and nc-CrAlN-a-CN is obtained. X Functional layer; Post-processing steps: Turn off the target and keep the pressure in the vacuum chamber at 1.0×10 −2 -3.0×10 −2 Pa, while maintaining the temperature at 100-120°C for 2-4 hours, and then taking it out of the furnace after cooling to 50-60°C.

5. The method for preparing a high heat-resistant composite multi-layer coating according to claim 4, characterized in that: The surface of the treated cemented carbide piston ring contains Cr 1-X Al X N / nc-CrAlN-a-CN X High sp of multi-layer transition layer 3 The thickness of the chromium bonding layer in the carbon-nitrogen film is 15-25nm; Cr in multi-layer transition layer 1-X Al X The thickness of the N single layer is 15-30nm, nc-CrAlN-a-CN X Functional layer is 500nm, high sp 3 sp in CN structure of carbon nitride film 3 The bond content is 45%-58%, and the mass fractions of Cr and Al in the coating are 15.5%-17.5% and 16.9%-18.2%, respectively.

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