A high heat-resistant composite multilayer coating and its preparation method

Abstract

This invention provides a high heat-resistant composite multilayer coating and its preparation method, specifically relating to the field of surface coating technology. The invention discloses a high heat-resistant composite multilayer coating comprising a Cr bonding layer, a Cr1-XAlXN / nc-CrAlN-a-CNX multilayer transition layer 3, and an nc-CrAlN-a-CNX functional layer sequentially coated on a cemented carbide substrate. The Cr1-XAlXN / nc-CrAlN-a-CNX multilayer transition layer and the nc-CrAlN-a-CNX functional layer proposed in this invention not only effectively bond Cr... 1‑X Al X N and CN X The enhanced properties and the composite multilayer structure endow it with excellent wear resistance, thereby achieving good lubrication and wear resistance in high-temperature environments. It significantly expands the high heat resistance of the amorphous carbon-nitrogen layer. At the same time, the transition of CrAl and C content in the composition and the construction method of multilayer support layer effectively improve the film-substrate bonding force between the substrate and the coating, enhance the toughness and load-bearing capacity of the top coating, alleviate the internal stress of the functional layer amorphous carbon layer, and significantly reduce the friction coefficient and wear rate of the amorphous carbon-based solid lubricating coating, thereby greatly improving the overall wear performance.

Description

Technical Field

[0001] This invention relates to the field of surface coating technology, and more specifically to a high heat-resistant composite multilayer coating and its preparation method. Background Technology

[0002] Piston rings are core components inside internal combustion engines. Together with cylinders, pistons, and cylinder walls, they seal fuel gases. With increasingly complex operating conditions, piston rings are experiencing wear failures and scrapping due to poor thermal stability under high-temperature conditions. How to prepare a coating with high heat resistance on the surface of piston rings is a problem that the automotive industry urgently needs to solve.

[0003] Solving the problem of friction and wear on the surface of mechanical components 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. Researching and developing nano-multilayer composite films that combine high heat resistance, low coefficient of friction, and high bonding strength with the substrate holds promise for reducing energy consumption in piston ring transmission systems, extending the service life of components, and improving the reliability and economy of automotive braking systems.

[0004] Composite metal nitrides possess high hardness and high wear resistance. CrAlN and CrAlSiN coatings have attracted significant attention from researchers. Compared to traditional TiN, TiCN, and TiAlN, composite metal nitride coatings exhibit higher red hardness and oxidation resistance, with an operating temperature reaching 800℃. This coating process is suitable for high-speed braking system components. Adding Si to form a CrAlSiN composite coating can improve the overall high-temperature oxidation resistance of the coating; however, its improvement on the self-lubricating performance of the composite film is limited. A nano-multilayer film Cr1-XAlXN / (nc-CrAlN-a-CNX) constructed using composite metal nitrides and a nitride system with nanocrystalline and amorphous composite structures exhibits good high-temperature oxidation resistance and comprehensive mechanical properties. Research shows that the composite nitride film has high adhesion to the metal substrate; the nanocrystalline lattice in the nanocrystalline-amorphous composite film is incomplete, preventing large lattice mismatch energies under external conditions, thus improving film adhesion; and the amorphous matrix easily adapts and matches with other microstructures.

[0005] Currently, there are few reports on nano-multilayer carbon-nitrogen-based coatings suitable for harsh operating conditions in the high-temperature range (800℃). Therefore, overcoming the poor thermal stability of carbon-nitrogen-based composite coatings and refining the particle size of doped phases in the coating 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 multilayer coating, which can effectively solve the problems mentioned in the prior art.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] The present invention provides a high heat-resistant composite multilayer coating, which consists of a Cr bonding layer, a Cr1-XAlXN / nc-CrAlN-a-CNX multilayer transition layer and an nc-CrAlN-a-CNX functional layer sequentially coated on a cemented carbide substrate.

[0009] Preferably, the Cr1-XAlXN / nc-CrAlN-a-CNX multilayer transition layer is formed by depositing a cross-decomposed graphite target and a CrAl composite target on the Cr bonding layer under a nitrogen atmosphere.

[0010] Preferably, the thickness of the Cr1-XAlXN / nc-CrAlN-a-CNX multilayer transition layer is 15-25 nm; the CrAl content in the nc-CrAlN-a-CNX functional layer gradually decreases along the direction away from the substrate, the C content gradually increases along the 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 includes the following steps:

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

[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, start the machine and evacuate to 2.0×10. -4 Pa, argon gas is introduced into the vacuum chamber, and the ion source is turned on to clean the substrate for 20 minutes. At the same time, the temperature is raised to 200-300℃ and baked for 0.5-2 hours.

[0014] Preparation steps of the Cr bonding layer: Turn off the ion source, turn off the argon gas, and evacuate to 1.0 × 10⁻⁶. -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 the Cr bonding layer;

[0015] Preparation steps of Cr1-XAlXN / nc-CrAlN-a-CNX multilayer transition layer: Turn off the Cr target, turn on the CrAl and graphite targets, introduce nitrogen gas, and maintain the chamber pressure at 1.0 × 10⁻⁶. -2 -3.0×10 -2Pa, 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 Cr1-XAlXN / nc-CrAlN-a-CNX multilayer transition layer;

[0016] Fabrication steps of nc-CrAlN-a-CNX functional layer: Gradually decrease the CrAl target arc current while gradually increasing the graphite target arc current to 80-90A, decrease the temperature to 100-120℃, and maintain the indoor air pressure at 1.0×10⁻⁶. -2 -3.0×10 -2 Pa, negative bias voltage of 500-650V, rotating substrate to maintain co-deposition of CrAl target and graphite target, to obtain nc-CrAlN-a-CNX functional layer;

[0017] Post-processing steps: Turn off the target and maintain the pressure in the vacuum chamber at 1.0 × 10⁻⁶. -2 -3.0×10 -2 Pa, while maintaining the temperature at 100-120℃, hold for 2-4 hours, and then remove from the furnace after cooling to 50-60℃.

[0018] Preferably, the surface of the treated cemented carbide piston ring contains a high sp2 layer of Cr1-XAlXN / nc-CrAlN-a-CNX multilayer transition layers. 3 The chromium bonding layer in the carbon-nitrogen film has a thickness of 150-250 nm; the thickness of the multilayer transition layer Cr1-XAlXN monolayer is 15-30 nm; the thickness of the nc-CrAlN-a-CNX functional layer is 500 nm; and the sp of the CN structure in the carbon-nitrogen 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.

[0019] The technical solution provided by this invention has the following advantages compared with the known prior art:

[0020] (1) Compared with the traditional CrN coating, the ternary Cr-Al-N coating formed by adding Al has greatly improved the 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 lubrication. Therefore, the friction and wear characteristics and coating load bearing capacity under high load conditions are significantly improved.

[0021] (2) The CrAlN coating still maintains a hardness of 27GPa at 1000℃, which is the best hardness value of nitrides at this temperature. Cr is the main element to improve the resistance to hot corrosion, and Al can promote the formation of a stable Al2O3 film. Therefore, the CrAlN coating has both good anti-corrosion performance and high-temperature oxidation resistance.

[0022] (3) The process of this invention is designed from two dimensions: component optimization and multilayer structure enhancement. The Cr1-XAlXN / nc-CrAlN-a-CNX multilayer transition layer and nc-CrAlN-a-CNX functional layer proposed in this invention not only effectively combine Cr 1- X Al X N and CN X The enhanced properties of the composite multilayer structure endow it with excellent wear resistance, thereby achieving good lubrication and wear resistance in high-temperature environments and significantly expanding the high heat resistance of the amorphous carbon-nitrogen layer. Simultaneously, the transition of CrAl and C content in the composition and the multilayer support layer construction method effectively improve the film-substrate adhesion between the substrate and the coating, enhance the toughness and load-bearing capacity of the top coating, alleviate the internal stress of the functional layer-like amorphous carbon layer, and play a role in buffering stress during friction, preventing the initiation of interface cracks. This significantly reduces the friction coefficient and wear rate of the amorphous carbon-based solid lubricating coating, resulting in a substantial improvement in overall wear performance.

[0023] (4) The high heat-resistant composite metal nitride / amorphous carbon nitride composite multilayer coating of the present invention achieves the coordinated unity of coating structure and function on the substrate surface of piston ring moving base parts, effectively improving the comprehensive performance and service life of the coating and the substrate, and can meet the urgent need for wear-resistant coatings in high-temperature environments. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0025] Figure 1 This is a schematic diagram of the coating layer in Embodiment 1 of the present invention.

[0026] In the picture:

[0027] 1. Piston ring base material; 2. Cr bonding layer; 3. Cr1-XAlXN / nc-CrAlN-a-CNX multilayer transition layer; 4. nc-CrAlN-a-CNX functional layer. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 creative effort are within the scope of protection of the present invention.

[0029] The present invention will be further described below with reference to embodiments.

[0030] Example 1:

[0031] Reference Figure 1 This embodiment discloses a method for preparing a high-heat-resistant composite multilayer coating. High-power pulsed magnetron sputtering technology is used to deposit a metal nitride / amorphous carbonitride composite multilayer coating on a pretreated substrate surface. The metal nitride / amorphous carbonitride composite multilayer coating includes a Cr bonding layer 2, a Cr1-XAlXN / nc-CrAlN-a-CNX multilayer transition layer 3, and an nc-CrAlN-a-CNX functional layer 4, sequentially formed on the substrate surface. The Cr1-XAlXN / nc-CrAlN-a-CNX multilayer transition layer 3 is formed by deposition on the Cr bonding layer 2 under a nitrogen atmosphere through cross-deposition of a graphite target and a CrAl composite target. 1- X Al X N-layer and nc-CrAlN-a-CN X The layer thickness is controlled within the range of 15-25 nanometers.

[0032] Furthermore, the substrate includes a cemented carbide substrate. Along the direction gradually moving away from the substrate, the CrAl content in the nc-CrAlN-a-CNX functional layer 4 shows a decreasing trend, the C content shows an increasing trend, while the N content is maintained within a range of 32% to 35%. This includes the following steps:

[0033] Step 1: Pre-treat the cemented carbide piston ring substrate by cleaning the substrate material in an ultrasonic cleaner for 10 minutes with anhydrous ethanol, then cleaning the substrate material in an ultrasonic cleaner for 10 minutes with acetone, and then drying it.

[0034] Step 2: Clamp the cemented carbide piston ring substrate with the Cr target, CrAl target, and high-purity graphite target; turn on the cooling water; and start the machine to evacuate to 2.0 × 10⁻⁶. -4 Pa, argon gas is introduced into the vacuum chamber, the ion source is turned on to clean the substrate for 15 minutes, and the temperature is raised to 200℃ and baked for 1 hour.

[0035] Step 3: Turn off the ion source and the argon gas, and evacuate to a vacuum of 2.0 × 10⁻⁶. -3 Pa, with the Cr target arc current set to 50A, negative bias voltage to 800V, and filter current to 10A, and deposition time to 20min, a pure Cr bonding layer 2 was obtained; the Cr target was turned off, and the CrAl and graphite targets were turned on, nitrogen gas was introduced, and the chamber pressure was maintained at 2.0×10 Pa. -2 Pa, set the CrAl target arc current to 70A and the negative bias voltage to 1000V, and set the graphite target arc current to 50V and the negative bias voltage to 700V, and perform cross deposition for 20s respectively to obtain Cr1-XAlXN / nc-CrAlN-a-CNX multilayer transition layer 3.

[0036] Step 4: Next, gradually decrease the CrAl target arc current while gradually increasing the graphite target arc current to 80A, lower the temperature to 120℃, and maintain the indoor air pressure at 2.0×10⁻⁶. -2 Pa, with a negative bias voltage of 500V, the substrate was rotated to maintain co-deposition of the CrAl and graphite targets, resulting in nc-CrAlN-a-CNX functional layer 4; then the target was turned off, and the pressure in the vacuum chamber was maintained at 2.0 × 10⁻⁶. - 2 Pa, while maintaining the temperature at 120℃, hold for 3 hours, and then remove from the furnace after cooling to 50℃.

[0037] Measurements showed that the piston ring surface contained a high sp3 layer of Cr1-XAlXN / nc-CrAlN-a-CNX multilayer transition layers. 3 The chromium bonding layer in the carbon-nitrogen film has a thickness of 150 nm; the thickness of the multilayer transition layer Cr1-XAlXN monolayer is 15 nm; the thickness of the nc-CrAlN-a-CNX functional layer 4 is 500 nm; and the sp of the CN structure in the carbon-nitrogen film... 3 The bond content is 58%, and the mass fractions of Cr and Al in the coating are 15.5% and 17.2%, respectively.

[0038] Example 2:

[0039] Step 1: Pre-treat the cemented carbide piston ring substrate by cleaning the substrate material in an ultrasonic cleaner for 10 minutes with anhydrous ethanol, then cleaning the substrate material in an ultrasonic cleaner for 10 minutes with acetone, and then drying it.

[0040] Step 2: Clamp the cemented carbide piston ring substrate with the Cr target, CrAl target, and high-purity graphite target; turn on the cooling water; and start the machine to evacuate to 2.0 × 10⁻⁶. -4 Pa, argon gas is introduced into the vacuum chamber, the ion source is turned on to clean the substrate for 25 minutes, and the temperature is raised to 250℃ and baked for 0.5 hours.

[0041] Step 3: Turn off the ion source and the argon gas, and evacuate to a vacuum of 3.0 × 10⁻⁶. -3 Pa, with the Cr target arc current set to 55A, negative bias voltage to 850V, and filter current to 12A, and deposition time to 25min, a pure Cr bonding layer 2 was obtained; the Cr target was turned off, and the CrAl and graphite targets were turned on, nitrogen gas was introduced, and the chamber pressure was maintained at 3.0×10⁻⁶. -2 Pa, set the CrAl target arc current to 80A and the negative bias voltage to 900V, and set the graphite target arc current to 55V and the negative bias voltage to 750V, and perform cross deposition for 30s to obtain Cr1-XAlXN / nc-CrAlN-a-CNX multilayer transition layer 3.

[0042] Step 4: Next, gradually decrease the CrAl target arc current while gradually increasing the graphite target arc current to 85A, lower the temperature to 110℃, and maintain the indoor air pressure at 3.0×10⁻⁶. -2 Pa, with a negative bias voltage of 550V, the substrate was rotated to maintain co-deposition of the CrAl and graphite targets, resulting in an nc-CrAlN-a-CNX functional layer 4; then the target was turned off, and the pressure in the vacuum chamber was maintained at 3.0 × 10 Pa. - 2 Pa, while maintaining the temperature at 110℃, hold for 4 hours, and then remove from the furnace after cooling to 60℃.

[0043] Measurements showed that the piston ring surface contained a high sp3 layer of Cr1-XAlXN / nc-CrAlN-a-CNX multilayer transition layers. 3 The chromium bonding layer in the carbon-nitrogen film has a thickness of 250 nm; the multilayer transition layer Cr 1-X Al X The N monolayer thickness is 20 nm, the nc-CrAlN-a-CNX functional layer 4 is 500 nm, and the sp of the CN structure in the carbon-nitrogen film... 3 The bond content is 50%, and the mass fractions of Cr and Al in the coating are 16.1% and 16.9%, respectively.

[0044] Example 3:

[0045] Step 1: Pre-treat the cemented carbide piston ring substrate by cleaning the substrate material in an ultrasonic cleaner for 10 minutes with anhydrous ethanol, then cleaning the substrate material in an ultrasonic cleaner for 10 minutes with acetone, and then drying it.

[0046] Step 2: Clamp the cemented carbide piston ring substrate with the Cr target, CrAl target, and high-purity graphite target; turn on the cooling water; and start the machine to evacuate to 2.0 × 10⁻⁶. -4 Pa, argon gas is introduced into the vacuum chamber, the ion source is turned on to clean the substrate for 20 minutes, and the temperature is raised to 300℃ and baked for 2 hours.

[0047] Step 3: Turn off the ion source and the argon gas, and evacuate to a vacuum of 2.0 × 10⁻⁶. -3 Pa, with the Cr target arc current set to 60A, negative bias voltage to 750V, filter current to 14A, and deposition time to 15min, a pure Cr bonding layer 2 was obtained; the Cr target was turned off, and the CrAl and graphite targets were turned on, nitrogen gas was introduced, and the chamber pressure was maintained at 1.0×10 Pa. -2 Pa, set the CrAl target arc current to 75A and the negative bias voltage to 950V, and set the graphite target arc current to 60V and the negative bias voltage to 800V, and perform cross deposition for 40s to obtain Cr1-XAlXN / nc-CrAlN-a-CNX multilayer transition layer 3.

[0048] Step 4: Next, gradually decrease the CrAl target arc current while gradually increasing the graphite target arc current to 80A, lower the temperature to 100℃, and maintain the indoor air pressure at 1.0×10⁻⁶. -2 Pa, with a negative bias voltage of 650V, the substrate was rotated to maintain co-deposition of the CrAl and graphite targets, resulting in nc-CrAlN-a-CNX functional layer 4; then the target was turned off, and the pressure in the vacuum chamber was maintained at 1.0 × 10⁻⁶. - 2 Pa, while maintaining the temperature at 100℃ for 2 hours, and then cooling it to 60℃ in the furnace before removing it from the furnace.

[0049] Measurements showed that the piston ring surface contained a high sp3 layer of Cr1-XAlXN / nc-CrAlN-a-CNX multilayer transition layers. 3 The chromium bonding layer in the carbon-nitrogen film has a thickness of 15 nm; the multilayer transition layer Cr1-XAlXN has a single-layer thickness of 30 nm; the nc-CrAlN-a-CNX functional layer 4 has a thickness of 500 nm; and the CN structure in the carbon-nitrogen film contains sp... 3 The bond content is 45%, and the mass fractions of Cr and Al in the coating are 17.5% and 18.2%, respectively.

[0050] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions 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 multilayer coating, characterized in that, It consists of a Cr bonding layer (2), a Cr1-XAlXN / nc-CrAlN-a-CNX multilayer transition layer (3), and an nc-CrAlN-a-CNX functional layer (4) sequentially coated on a cemented carbide substrate.

2. The high heat-resistant composite multilayer coating according to claim 1, characterized in that, The Cr1-XAlXN / nc-CrAlN-a-CNX multilayer transition layer (3) is formed by depositing a cross-decomposed graphite target and a CrAl composite target on the Cr binding layer (2) under a nitrogen atmosphere.

3. The high heat-resistant composite multilayer coating according to claim 1, characterized in that, The thickness of the Cr1-XAlXN / nc-CrAlN-a-CNX multilayer transition layer (3) is 15-25 nm; The CrAl content in the nc-CrAlN-a-CNX functional layer (4) gradually decreases along the direction away from the matrix, the C content gradually increases along the direction away from the matrix, and the N content is 32% to 35%.

4. A method for preparing a high heat-resistant composite multilayer coating according to any one of claims 1 to 3, characterized in that, Includes the following steps: Pretreatment steps: Clean the hard alloy piston ring substrate material (1) with anhydrous ethanol in an ultrasonic cleaner for 10 min, then clean the substrate material with acetone in an ultrasonic cleaner for 10 min, and then dry it; Vacuum and cleaning steps: Clamp the piston ring substrate and Cr target, CrAl target and high-purity graphite target, turn on the cooling water, start the machine and evacuate to 2.0×10. -4 Pa, argon gas is introduced into the vacuum chamber, and the ion source is turned on to clean the substrate for 20 minutes. At the same time, the temperature is raised to 200-300℃ and baked for 0.5-2 hours. Preparation steps of Cr-bonded layer (2): 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 the Cr bonding layer (2). Preparation steps of Cr1-XAlXN / nc-CrAlN-a-CNX multilayer transition layer (3): Turn off the Cr target, turn on the CrAl and graphite targets, introduce nitrogen gas, and maintain the indoor gas 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 Cr1-XAlXN / nc-CrAlN-a-CNX multilayer transition layer (3). nc-CrAlN-a-CNX functional layer (4) preparation steps: Gradually reduce the CrAl target arc current, while gradually increasing the graphite target arc current to 80-90A, reduce the temperature to 100-120℃, and maintain the indoor air pressure at 1.0×10 -2 -3.0×10 -2 Pa, negative bias voltage of 500-650V, rotating substrate to maintain co-deposition of CrAl target and graphite target, to obtain nc-CrAlN-a-CNX functional layer (4). Post-processing steps: Turn off the target and maintain the pressure in the vacuum chamber at 1.0 × 10⁻⁶. -2 -3.0×10 -2 Pa, while maintaining the temperature at 100-120℃, hold for 2-4 hours, and then remove from the furnace after cooling to 50-60℃.

5. The method for preparing a high heat-resistant composite multilayer coating according to claim 4, characterized in that, The surface of the treated cemented carbide piston ring contains a high sp content of Cr1-XAlXN / nc-CrAlN-a-CNX multilayer transition layer (3). 3 The thickness of the chromium bonding layer in the carbon-nitrogen film is 15-25 nm; Cr in multilayer transition layer 1-X Al X The thickness of the N monolayer is 15-30 nm, and the nc-CrAlN-a-CNX functional layer (4) is 500 nm, with high sp 3 sp of CN structure in carbon-nitrogen 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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