Stainless steel composite material and method for manufacturing the same

Abstract

The application provides a stainless steel composite material and a preparation method of the stainless steel composite material, and the preparation method comprises the following steps: performing first nitriding treatment on a stainless steel base body, so that a nitriding layer is formed on the surface of the stainless steel base body; performing pickling on the stainless steel base body with the nitriding layer, and then performing cleaning and drying; and performing magnetron sputtering on the stainless steel base body after the pickling treatment, so that a WCrAlSiTiN coating layer is formed on the surface of the nitriding layer. The preparation method can effectively improve the comprehensive performance of the stainless steel. The nitriding layer can not only improve the corrosion resistance and wear resistance of the stainless steel base body, but also improve the strength of the stainless steel base body, so that the stainless steel base body and the WCrAlSiTiN coating layer have good hardness matching, the bonding strength of the coating layer and the stainless steel base body is improved, the effectiveness of the coating layer is ensured, the hardness, wear resistance and corrosion resistance of the stainless steel are further improved through the deposited WCrAlSiTiN coating layer, and the service life of the stainless steel in a high-salt and high-humidity environment such as the ocean is prolonged.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of stainless steel processing, in particular to a stainless steel composite material and a preparation method of the stainless steel composite material. BACKGROUND

[0002] Stainless steel is widely used in the preparation of parts that bear impact load and have certain corrosion resistance requirements, such as large axial flow compressor blades, turbine blades, fasteners, valve bodies, shaft pump sleeves and bearings, because of its high strength and good mechanical properties. However, the wear resistance and corrosion resistance of stainless steel are relatively poor, and it is prone to corrosion in marine environment, which not only limits its application in petrochemical ships and marine engineering fields, but also seriously affects its service life.

[0003] To this end, the existing solution is to form a coating on the stainless steel. The existing coating preparation has defects such as complex process, high cost, poor corrosion resistance and strength, and coating failure, which cannot fully meet the use requirements of stainless steel in marine environment. SUMMARY

[0004] The purpose of the present application is to provide a stainless steel composite material and a preparation method of the stainless steel composite material. The stainless steel composite material provided by the present application has good performance.

[0005] The present application provides a preparation method of a stainless steel composite material, which comprises the following steps:

[0006] The stainless steel substrate is subjected to first nitriding treatment, so as to form a nitriding layer on the surface of the stainless steel substrate;

[0007] The stainless steel substrate with the nitriding layer is subjected to pickling, and then is cleaned and dried;

[0008] The stainless steel substrate after the pickling treatment is subjected to magnetron sputtering, so as to form a WCrAlSiTiN coating layer on the surface of the nitriding layer.

[0009] In some embodiments of the present application, the nitriding temperature of the first nitriding treatment is 350℃-480℃; and the nitriding gas of the first nitriding treatment is ammonia.

[0010] In some embodiments of the present application, the pickling of the stainless steel substrate with the nitriding layer, and then cleaning and drying, comprises:

[0011] The stainless steel substrate with the nitriding layer is immersed in an acidic solution for 1min-2min, and then is ultrasonically cleaned with anhydrous ethanol and / or acetone for 5min-10min, and then is dried at 100-150℃;

[0012] The acid solution is a mixed solution of nitric acid and hydrofluoric acid.

[0013] In some embodiments of the present application, the magnetron sputtering of the stainless steel substrate after the pickling treatment to form a WCrAlSiTiN coating layer on the surface of the nitriding layer comprises:

[0014] Depositing a Cr layer: turning on a Cr target to deposit the Cr layer on the nitriding layer, the Cr target current being 60A-90A, the negative bias being 500V-800V, and the deposition time being 1min-5min;

[0015] Depositing a CrN layer: introducing nitrogen into the sputtering chamber while turning on the Cr target, the Cr target current being 60A-90A, the negative bias being 100V-200V, and the deposition time being 30min-90min;

[0016] Depositing a CrAlSiN layer: continuing to introduce nitrogen into the sputtering chamber while turning on the Cr target and the AlSi target, the Cr target and the AlSi target current both being 70A-90A, the negative bias being 100V-200V, and the deposition time being 30min-90min;

[0017] Depositing a CrAlTiSiN layer: continuing to introduce nitrogen into the sputtering chamber and using the Cr target, the AlTiSi target and the AlTi target to deposit the CrAlTiSiN layer on the CrAlSiN layer;

[0018] Depositing a CrWAlTiN layer: continuing to introduce nitrogen into the sputtering chamber while turning on the W target, the Cr target and the AlTi target, the current of each target being 60A-90A, the negative bias being 200V-300V, and the deposition time being 60min-120min, wherein the number of the Cr target turned on is greater than the number of the W target;

[0019] Depositing a WCrAlTiN layer: continuing to introduce nitrogen into the sputtering chamber while turning on the W target, the Cr target and the AlTi target, the current of each target being 60A-90A, the negative bias being 200V-300V, and the deposition time being 60min-120min, wherein the number of the Cr target turned on is less than the number of the W target;

[0020] Alternately performing the step of depositing the CrWAlTiN layer and the step of depositing the WCrAlTiN layer for a preset number of times.

[0021] In some embodiments of the present application, the step of depositing the CrAlTiSiN layer specifically comprises:

[0022] Step 1: continue to introduce nitrogen into the sputtering cavity, and deposit a first sub-layer by starting the Cr target and the AlTiSi target, the current of the Cr target and the AlTiSi target is 30A-60A, the negative bias is 200V-300V, and the deposition time is 5min-10min;

[0023] Step 2: continue to introduce nitrogen into the sputtering cavity, and deposit a second sub-layer by starting the Cr target, the AlTiSi target and the AlTi target, the current of the Cr target is 30A-60A, the current of the AlTiSi target is 60A-80A, the current of the AlTi target is 50A-70A, the negative bias is 200V-300V, and the deposition time is 0.1min-1min;

[0024] Step 3: on the basis of step 2, the current of the AlTi target is reduced to 20A-40A, and the current of other targets remains unchanged, a third sub-layer is deposited under a negative bias of 200V-300V, and the deposition time is 0.1min-1min;

[0025] The step 2 and the step 3 are alternately performed for a preset number of times;

[0026] Step 4: continue to introduce nitrogen into the sputtering cavity, and deposit a fourth sub-layer by starting the Cr target, the AlTiSi target and the AlTi target, the current of each target is 70A-90A, the negative bias is 100V-200V, and the deposition time is 0.1min-1min;

[0027] Step 5: on the basis of step 4, the number of the Cr target started is reduced, the current of each target remains unchanged, a fifth sub-layer is deposited under a negative bias of 100V-200V, and the deposition time is 0.1min-1min;

[0028] The step 4 and the step 5 are alternately performed for a preset number of times;

[0029] Step 6: on the basis of step 4, the deposition time is set to 1min-2min, and a sixth sub-layer is deposited;

[0030] Step 7: on the basis of step 5, the deposition time is set to 1min-2min, and a seventh sub-layer is deposited.

[0031] In some embodiments of the present application, the step of preparing the Cr film layer further comprises, before depositing the Cr layer on the nitriding layer:

[0032] nitrogen-containing gas is introduced into the sputtering cavity to perform a second nitriding treatment on the stainless steel substrate on which the nitriding layer is formed;

[0033] The nitriding temperature of the second nitriding treatment is 350 DEG C to 480 DEG C; the nitriding gas of the second nitriding treatment is ammonia; and the nitriding time of the second nitriding treatment is 5 min to 10 min

[0034] In some embodiments of the present application, before the step of performing the first nitriding treatment on the stainless steel substrate to form the nitriding layer on the surface of the stainless steel substrate, the method further comprises:

[0035] The stainless steel substrate is sequentially subjected to cutting, grinding, polishing and surface cleaning treatment.

[0036] In some embodiments of the present application, the stainless steel substrate is a martensitic stainless steel substrate.

[0037] The present application also provides a stainless steel composite material, comprising: a stainless steel substrate; a nitriding layer arranged on the surface of the stainless steel substrate; and a WCrAlSiTiN coating layer arranged on the side of the nitriding layer away from the stainless steel substrate.

[0038] In some embodiments of the present application, the WCrAlSiTiN coating layer comprises a Cr layer, a CrN layer, a CrAlSiN layer, a CrAlTiSiN layer, a CrWAlTiN layer and a WCrAlTiN layer arranged alternately on the nitriding layer, wherein the content of Cr element in the CrWAlTiN layer is greater than the content of W element, and the content of Cr element in the WCrAlTiN layer is less than the content of W element.

[0039] In some embodiments of the present application, the CrAlTiSiN layer has a multilayer structure, which comprises at least one first sublayer, M periodic alternately arranged second sublayers and third sublayers, N periodic alternately arranged fourth sublayers and fifth sublayers, at least one sixth sublayer and at least one seventh sublayer along the direction away from the nitriding layer, the content of Al element and Ti element in the second sublayer is greater than the content of Al element and Ti element in the first sublayer and the third sublayer, and the content of Cr element in the fourth sublayer is greater than the content of Cr element in the fifth sublayer.

[0040] In some embodiments of the present application, 10≤M≤50 and 15≤N≤25.

[0041] In some embodiments of the present application, the CrWAlTiN layer and the WCrAlTiN layer are alternately arranged for 20 to 25 times.

[0042] From the above technical solution, the present application has the following advantages and positive effects:

[0043] The stainless steel composite material prepared by the preparation method can effectively improve the comprehensive performance of the stainless steel, including the mechanical property, wear resistance and corrosion resistance; the nitriding layer can not only improve the corrosion resistance and wear resistance of the stainless steel substrate, but also improve the hardness matching between the stainless steel substrate and the WCrAlSiTiN coating, so as to improve the bonding strength between the coating and the stainless steel substrate, ensure the service life of the coating, and further improve the hardness, wear resistance and corrosion resistance of the stainless steel, so that the hardness of the stainless steel can reach more than 2000HV0.1, the self-corrosion current density is low, and the service life of the instrument and equipment using the stainless steel as the material in the high-salt and high-humidity environment such as the sea is prolonged, and the coating structure deposited on the whole stainless steel surface is simple and convenient to operate. BRIEF DESCRIPTION OF DRAWINGS

[0044] Figure 1 is a flow chart of the preparation method of the stainless steel composite material according to an embodiment of the present application.

[0045] Figure 2 is a flow chart of the WCrAlSiTiN coating formed according to an embodiment of the present application.

[0046] Figure 3 is a structural schematic diagram of the stainless steel composite material according to an embodiment of the present application.

[0047] Figure 4 is an XRD spectrum of the prepared stainless steel composite material.

[0048] Figure 5 is a cross-sectional morphology diagram of different samples under an optical microscope.

[0049] Figure 6 is a hardness value result diagram of the prepared stainless steel composite material.

[0050] Figure 7 is a result diagram of the cross-sectional hardness gradient analysis of different samples respectively subjected to a load load.

[0051] Figure 8 is a polarization curve diagram of different samples subjected to an electrochemical corrosion test in a seawater solution.

[0052] Figure 9 is a surface morphology diagram of different samples subjected to an electrochemical corrosion test in a seawater solution.

[0053] Figure 10 is an EIS spectrum of different samples subjected to an electrochemical corrosion test in a seawater solution. DETAILED DESCRIPTION

[0054] The features and advantages of the present application will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings. It is understood that various changes can be made within the scope of the application, and the description and drawings are to be regarded as illustrative in nature and not as restrictive.

[0055] To further illustrate the principles and configurations of the present application, preferred embodiments of the present application will now be described in detail in connection with the accompanying drawings.

[0056] The wear resistance and corrosion resistance of steel materials, such as low alloy steel and stainless steel, are poor. The prior art usually improves the wear resistance and corrosion resistance of the steel substrate by preparing a modified coating on the steel substrate, for example, forming a hard coating of CrN, CrWN, CrAlN, etc. on the surface of the steel substrate. However, since the hardness of the coating itself is higher than the surface hardness of the substrate, if the carrying capacity of the substrate is not enough, the coating may fail.

[0057] The existing method for preparing a coating for performance improvement is mostly applied to low alloy steel. For stainless steel, such as martensitic stainless steel, there is a lack of effective surface treatment method. Since the hardness of the martensitic stainless steel is relatively low and the carrying capacity is poor, in the process of improving the performance by setting a coating, the coating may be easily broken due to the lack of smooth transition between the substrate and the coating, resulting in a large difficulty in surface modification and poor effect.

[0058] Based on this, the present application provides a preparation method of a composite modified layer on a surface of a stainless steel. Please refer to Figure 1 The preparation method comprises the following steps:

[0059] S101, performing first nitriding treatment on a stainless steel substrate to form a nitriding layer on the surface of the stainless steel substrate;

[0060] S102, performing pickling on the stainless steel substrate with the nitriding layer formed thereon, and then cleaning and drying;

[0061] S103, performing magnetron sputtering on the stainless steel substrate after the pickling treatment to form a WCrAlSiTiN coating on the surface of the nitriding layer.

[0062] In step S101, the first nitriding treatment can make nitrogen elements penetrate into the surface layer of the stainless steel substrate to form a nitriding layer on the surface of the stainless steel substrate. On the one hand, the nitriding layer can improve the corrosion resistance and wear resistance of the stainless steel substrate. On the other hand, the nitriding layer can improve the strength of the stainless steel substrate to enhance the carrying capacity thereof.

[0063] The first nitriding treatment can adopt any nitriding process commonly used in the art, such as gas-liquid nitriding, gas nitriding, ion nitriding, etc., and preferably ion nitriding.

[0064] In step S102, the nitride attached to the surface layer of the nitriding layer, the oxide film and the "Cr" poor layer can be removed by pickling, which is beneficial to improve the density, hardness and corrosion resistance of the nitriding layer, and is beneficial to the attachment and formation of the WCrAlSiTiN coating and the improvement of the bonding strength between the nitriding layer. Compared with the method of removing the loose layer and passivation layer on the surface of the nitriding layer by polishing, sand blasting and other physical means after nitriding, the operation process is convenient and fast, the removal efficiency and effect are significantly improved, and the stainless steel substrate and the surface of the nitriding layer are not damaged.

[0065] In the process of pickling, a small amount of H element diffuses into the stainless steel substrate and the nitriding layer, and the H element can be precipitated by drying treatment to eliminate its influence on the strength and corrosion resistance of the stainless steel substrate and the nitriding layer.

[0066] In step S103, the coating is formed by magnetron sputtering. Compared with multi-arc ion plating, the surface of the formed coating is more dense, uniform and flat. Such dense, uniform and flat surface can better resist the erosion of corrosive medium. Moreover, the formed coating contains Cr, N, Ti, Al, W and Si, and the above-mentioned elements synergistically improve the hardness, corrosion resistance and friction resistance of the obtained coating. For example, the W, Cr, Al, Si, Ti and N in the WCrAlSiTiN coating exist in the form of mutual bonding in the coating, so that the strength of the coating is significantly increased. For example, the addition of Si element changes the columnar crystal structure of the CrN film layer to the nanocrystalline composite structure of Si3N4 interface phase wrapped nanocrystalline TiN, so that the hardness and stress of the coating are significantly increased, and the addition of Si element obviously improves the oxidation resistance of the coating. For example, the addition of W element improves the toughness and friction resistance of the coating, thereby improving the wear resistance of the substrate, and the addition of W element increases the coordination strain, thereby improving the hardness of the film layer.

[0067] In some embodiments of the present application, the nitriding temperature of the first nitriding treatment is 350-480°C, and specifically, for example, can be 350°C, 360°C, 380°C, 400°C, 420°C, 440°C or 880°C. The present application finds that, by implementing the nitriding treatment in this temperature range, the phenomenon of "Cr" deficiency in the stainless steel substrate can be effectively avoided, so that the surface hardness and corrosion resistance of the stainless steel substrate after nitriding can be improved. The first nitriding treatment at this treatment temperature can maximize the surface performance of the stainless steel without the phenomenon of "Cr" deficiency.

[0068] In some embodiments of the present application, the nitriding gas of the first nitriding treatment is ammonia.

[0069] In the cleaning and heating process of the first nitriding treatment of the application, ammonia is used as the nitriding gas alone, and the ammonia can enable the N element to penetrate into the stainless steel substrate during the heating process, which helps to obtain a thicker nitriding layer, improves the nitriding efficiency, and the use of single gas can avoid the influence of other gases on the process and save costs.

[0070] In some embodiments of the application, the nitriding pressure of the first nitriding treatment is controlled at 2.5*10 2 Pa or more, preferably 2.5*10 2 Pa~3*10 2 Pa, and specifically, for example, can be 2.5*10 2 Pa, 2.6*10 2 Pa, 2.7*10 2 Pa, 2.8*10 2 Pa, 2.9*10 2 Pa or 3*10 2 Pa. The nitriding treatment at this nitriding pressure can obtain a nitriding layer with higher density. In actual operation, the greater the pressure, the higher the ammonia concentration, the higher the concentration of generated nitrogen ions, and the more intense the reaction of nitrogen ions bombarding the surface of the workpiece. The speed of nitriding treatment can be accelerated, the nitriding layer formed by the bombardment of nitrogen atoms on the stainless steel substrate has more and uniformly distributed nitrides, thereby improving the corrosion resistance of the stainless steel substrate.

[0071] In the application, by optimizing the temperature, nitriding gas and nitriding pressure and other parameters of the first nitriding treatment, the nitriding efficiency can be improved, and a nitriding layer with higher density and better corrosion resistance can be obtained.

[0072] The process equipment of the first nitriding treatment in the application can use a pit-type nitriding furnace, a bell-type furnace or a box-type furnace, but is not limited thereto. In the method described in the application, the duration of the first nitriding treatment can be determined according to the thickness of the nitriding layer to be obtained. The longer the duration of the heat preservation reaction, the thicker the nitriding layer, and the better the corrosion resistance. However, if the nitriding layer is too thick, it may cause poor adhesion of the WCrAlSiTiN coating, so it needs to be determined in combination with the actual application situation.

[0073] In some embodiments of the application, the pickling of the stainless steel substrate formed with the nitriding layer is followed by cleaning and drying, which comprises:

[0074] The stainless steel substrate formed with the nitriding layer is immersed in an acidic solution for 1-2 minutes, then ultrasonically cleaned with anhydrous ethanol and / or acetone for 5-10 minutes, and then dried at 100-150°C.

[0075] By using the pickling solution to soak and using anhydrous ethanol and / or acetone to clean, the passivation layer and surface impurities can be effectively removed to obtain a clean surface, so that the deposited coating can better combine with the surface of the stainless steel substrate. The drying treatment at 100-150℃ can cause the H element permeated into the stainless steel substrate to be precipitated, so as to eliminate its influence on the strength and corrosion resistance of the stainless steel substrate.

[0076] The acid solution can be any solution commonly used in the art which can remove the surface passivation layer and loose layer, and preferably the acid solution is a mixed solution of nitric acid and hydrofluoric acid.

[0077] In some embodiments of the present application, referring to Figure 2 , the magnetron sputtering is performed on the stainless steel substrate after the pickling treatment to form a WCrAlSiTiN coating layer on the surface of the nitriding layer, comprising:

[0078] S201, depositing a Cr layer: turn on the Cr target to deposit the Cr layer on the nitriding layer, the Cr target current is 60A-90A, the negative bias is 500V-800V, and the deposition time is 1min-5min;

[0079] S202, depositing a CrN layer: nitrogen gas is introduced into the sputtering chamber while the Cr target is turned on, the Cr target current is 60A-90A, the negative bias is 100V-200V, and the deposition time is 30min-90min;

[0080] S203, depositing a CrAlSiN layer: continue to introduce nitrogen gas into the sputtering chamber while turning on the Cr target and the AlSi target, the current of the Cr target and the AlSi target is both 70A-90A, the negative bias is 100V-200V, and the deposition time is 30min-90min;

[0081] S204, depositing a CrAlTiSiN layer: continue to introduce nitrogen gas into the sputtering chamber, and use the Cr target, the AlTiSi target and the AlTi target to deposit the CrAlTiSiN layer on the CrAlSiN layer;

[0082] S205, depositing a CrWAlTiN layer: continue to introduce nitrogen gas into the sputtering chamber while turning on the W target, the Cr target and the AlTi target, the current of each target is 60A-90A, the negative bias is 200V-300V, and the deposition time is 60min-120min, wherein the number of the Cr target turned on is greater than the number of the W target;

[0083] S206, depositing a WCrAlTiN layer: continue to introduce nitrogen into the sputtering cavity, while turning on the W target, the Cr target and the AlTi target, the current of each target is 60A-90A, the negative bias is 200V-300V, and the deposition time is 60min-120min, wherein the number of the Cr target turned on is less than the number of the W target;

[0084] S207, alternately performing the step of depositing a CrWAlTiN layer and the step of depositing a WCrAlTiN layer for a preset number of times.

[0085] In one aspect, the WCrAlSiTiN coating prepared in the present application contains W, Cr, Al, Si, Ti and N six elements, which exist in the form of mutual bonding in the coating, so that the strength of the coating is improved, wherein the addition of Si can form Si-N in the coating, and the presence of Si-N bond indicates that the coating may form a silicon nitride structure in its growth direction, which is a high-hardness inorganic material at room temperature, so that the overall hardness of the thin film is significantly increased, in addition, the addition of Si element changes the columnar crystal structure of the CrN film layer to a nano-crystalline composite structure of Si3N4 interface phase wrapped nano-crystalline TiN, so that the hardness and stress of the coating are significantly increased, and the addition of Si improves the oxidation resistance of the coating. For example, the addition of W element can improve the strength and toughness of the coating and the anti-friction performance, thereby improving the wear resistance of the substrate, and the addition of W element can increase the coordination strain, thereby improving the hardness of the film layer.

[0086] On the other hand, the WCrAlSiTiN coating prepared in the present application is a nano-multilayer structure of WN phase, first, nanoization and multilayerization can improve the film-substrate bonding ability, second, the cooperation of multiple film layers can form a transition bonding area, relieve the lattice difference and the sudden change of the thermal expansion coefficient, improve the stability and strength, and the element diffusion between the film layers forms a structure similar to mechanical locking, which makes the bonding between the film layers more tight and firm, greatly increases the strength and wear resistance of the coating, and prolongs the service life of the coating.

[0087] In still another aspect, the side of the coating layer close to the nitriding layer is a Cr layer, which ensures good film-substrate adhesion, and the side far from the nitriding layer is an alternating layer stack of Cr(many)W(few)AlTiN and W(many)Cr(few)AlTiN. Such an alternating arrangement structure can produce satellite peaks, thereby forming a superlattice structure with a completely coherent interface. The superlattice thin film is a layered fine composite material that maintains a specific form, can effectively improve the mechanical properties of the thin film and has superior wear resistance and friction reduction, and has super hardness. In the W-Cr-Al-Ti-N superlattice thin layer, the crystal structures of the constituent materials are all face-centered cubic structures, and the CrN, W2N and TiN are in a polycrystalline epitaxial growth mode, forming a coherent interface at the interface, producing coordinated strain, and increasing the hardness of the coating layer. The amorphous Si3N4 is mostly filled in the grain boundary area, and the dislocation will pass through the amorphous phase with small hardness, be blocked by the amorphous Si3N4 phase with high modulus on the grain boundary, and the crack is prevented and reflected by the Si3N4 to be deflected, thereby increasing the toughness of the film layer and improving the film-substrate adhesion.

[0088] The number of times of alternately performing the step of depositing the CrWAlTiN layer and the step of depositing the WCrAlTiN layer is determined according to actual conditions, and is not limited in the present application.

[0089] In some embodiments of the present application, the step of preparing the CrAlTiSiN layer specifically comprises:

[0090] Step 1: continue to introduce nitrogen into the sputtering cavity, and simultaneously turn on the Cr target and the AlTiSi target to deposit a first sub-layer, the current of the Cr target and the AlTiSi target is 30A-60A, the negative bias is 200V-300V, and the deposition time is 5min-10min;

[0091] Step 2: continue to introduce nitrogen into the sputtering cavity, and simultaneously turn on the Cr target, the AlTiSi target and the AlTi target to deposit a second sub-layer, the current of the Cr target is 30A-60A, the current of the Al-Ti-Si target is 60A-80A, the current of the Al-Ti target is 50A-70A, the negative bias is 200V-300V, and the deposition time is 0.1min-1min;

[0092] Step 3: on the basis of step 2, the current of the AlTi target is reduced to 20A-40A, and the current of the other targets remains unchanged, a third sub-layer is deposited under a negative bias of 200V-300V, and the deposition time is 0.1min-1min;

[0093] The step 2 and the step 3 are alternately performed for a preset number of times;

[0094] Step 4: continue to introduce nitrogen into the sputtering cavity, and meanwhile, deposit a fourth sub-layer by starting the Cr target, the Al-Ti-Si target and the Al-Ti target, each target current being 70A-90A, the negative bias being 100V-200V, and the deposition time being 0.1min-1min;

[0095] Step 5: on the basis of Step 4, reduce the number of the Cr target to be started, keep the target current unchanged, deposit a fifth sub-layer under the negative bias of 100V-200V, and the deposition time being 0.1min-1min;

[0096] alternately perform the Step 4 and the Step 5 for a preset number of times;

[0097] Step 6: on the basis of Step 4, set the deposition time to be 1min-2min, and deposit a sixth sub-layer;

[0098] Step 7: on the basis of Step 5, set the deposition time to be 1min-2min, and deposit a seventh sub-layer.

[0099] In the present application, the CrAlTiSiN layer is formed into a multi-layer structure by regulating the target current, the target running number and the deposition time, so that satellite peaks also appear in the CrAlTiSiN layer, thereby forming a superlattice structure with a completely coherent interface. The element content between at least the second sub-layer and the third sub-layer and between the fourth sub-layer and the fifth sub-layer changes alternately in the film thickness direction, so that the organization, structure and performance of the CrAlTiSiN layer also change alternately, thereby having excellent thermal stress relaxation ability, excellent thermal shock resistance, good film-substrate adhesion, excellent wear resistance and the like, and meanwhile, having excellent oxidation resistance at high temperature.

[0100] In some embodiments of the present application, the step of preparing the Cr layer further comprises, before depositing the Cr layer on the nitriding layer:

[0101] introducing a nitriding gas into the sputtering cavity to perform a second nitriding treatment on the stainless steel substrate on which the nitriding layer is formed;

[0102] The nitriding temperature of the second nitriding treatment is 350℃-480℃; the nitriding gas of the second nitriding treatment is ammonia; and the nitriding time of the second nitriding treatment is 5min-10min.

[0103] By performing the second nitriding on the stainless steel substrate before plating, the nitriding layer depth is improved, the smoothness of the sample surface is effectively ensured, the plating is facilitated, the influence of impurities on the sample surface on the coating adhesion is reduced, and the combination of the WCrAlSiTiN coating and the stainless steel substrate is more closely and firmly.

[0104] In some embodiments of the present application, before the step of performing the first nitriding treatment on the stainless steel substrate to form a nitriding layer on the surface of the stainless steel substrate, the method further comprises:

[0105] The stainless steel substrate is sequentially subjected to cutting, grinding, polishing and surface cleaning treatment.

[0106] The cutting, grinding, polishing and surface cleaning treatment can be in a manner conventional in the art. In a specific embodiment, the polishing treatment can be performed by, for example, sand blasting, shot blasting or the like, which can effectively remove rust and impurities on the surface of the stainless steel substrate and improve the density and corrosion resistance of the nitriding layer. The polishing treatment is mainly performed by mechanical polishing. The surface cleaning treatment is mainly to clean and remove oil stains on the surface of the stainless steel substrate.

[0107] In some embodiments of the present application, the stainless steel substrate is a martensitic stainless steel substrate. The method of the present application forms a composite surface layer with high hardness, high bonding strength, low friction coefficient and corrosion resistance on the surface of the martensitic stainless steel, thereby improving the comprehensive performance of the martensitic stainless steel.

[0108] According to a specific embodiment of the present application, the method for preparing the stainless steel composite material specifically comprises the following steps:

[0109] (1) Pretreatment of the stainless steel substrate

[0110] The martensitic stainless steel bar is cut to obtain a pretreated sample. The pretreated martensitic stainless steel workpiece is ground and polished to obtain a clean workpiece. The martensitic stainless steel workpiece obtained by the above steps is subjected to ultrasonic cleaning twice using acetone and alcohol, respectively, and finally subjected to blow-drying treatment.

[0111] (2) First nitriding treatment

[0112] The power supply of the nitriding equipment is turned on, the pressure relief valve is opened, and the vacuum chamber is ensured to be at the first stage pressure (9.8x10 4 ~1x10 5 Pa). The furnace shell of the ion nitriding equipment is opened, the workpiece obtained by the above steps is placed in the vacuum chamber of the ion nitriding equipment, and the furnace shell is closed. The pressure relief valve is closed, and the mechanical pump is turned on to draw the vacuum chamber to the second stage pressure (0~3x10 1Pa). Turn on the high voltage switch, turn on the temperature switch, set the nitriding temperature (350-480°C), wait for the nitriding equipment to rise to the first stage temperature (0-100°C), set the first stage bias (550-600V), slowly increase the first stage duty cycle (0-25%). Wait for the nitriding equipment to run stably, set the second stage bias (600-650V), slowly increase the second stage duty cycle (25-35%), wait for the nitriding equipment to stabilize, slowly increase the third stage duty cycle (35-55%), wait for the nitriding equipment to stabilize, slowly increase the fourth stage duty cycle (55-80%), wait for the nitriding equipment to stabilize, open the gas cylinder switch, introduce the nitriding gas, adjust the nitriding equipment to reach the third stage gas pressure (3x10 1 ~5x10 1 Pa), and bombard the surface for 10-20 minutes. The nitriding gas is ammonia.

[0113] After cleaning, continue to introduce the nitriding gas, slowly increase the gas pressure in the nitriding equipment to the fourth stage gas pressure (5x10 1 ~1x10 2 Pa). Wait for the nitriding equipment to reach the second stage temperature (100-150°C), increase the flow of nitriding gas, and increase the pressure in the nitriding equipment to the fifth stage gas pressure (1x10 2 ~1.5x10 2 Pa), set the third stage bias (650-700V). Wait for the nitriding equipment to reach the third stage temperature (150-250°C), increase the flow of nitriding gas, and increase the pressure in the nitriding equipment to the sixth stage gas pressure (1.5x10 2 ~2x10 2 Pa). Wait for the nitriding equipment to reach the fourth stage temperature (250-300°C), open the circulating cooling water, increase the flow of nitriding gas, and increase the pressure in the nitriding equipment to the seventh stage gas pressure (2x10 2 ~2.5x10 2 Pa). Wait for the nitriding equipment to reach the fifth stage temperature (300-450°C), increase the flow of nitriding gas, and increase the pressure in the nitriding equipment to the eighth stage gas pressure (2.5x10 2 ~3x10 2 Pa), set the fourth stage bias (700-750V).

[0114] After the nitriding equipment reaches the nitriding temperature, start the holding time. After the holding time is reached, continue to introduce the nitriding gas, and adjust the pressure in the nitriding equipment to the ninth stage gas pressure (0-3x10 1Pa), slowly adjust the duty ratio and bias to 0, turn off the high voltage switch, and turn off the temperature switch. Wait until the temperature in the nitriding equipment reaches the sixth stage temperature (25-50°C), stop the inert gas, turn off the gas cylinder, turn off the mechanical pump, open the pressure relief valve, and wait until the pressure in the nitriding equipment reaches the tenth stage pressure (9.8 x 10 4 ~1 x 10 5 Pa). Open the nitriding equipment furnace shell and remove the nitrided workpiece.

[0115] Turn off the furnace shell, turn off the pressure relief valve, turn on the vacuum pump, and make the nitriding equipment at the eleventh stage pressure (0-3 x 10 1 Pa). Turn off the mechanical pump and turn off the power of the nitriding equipment.

[0116] (3) Pickling

[0117] The martensitic stainless steel workpiece after the above treatment is pickled (1-2 min), and then ultrasonically cleaned with anhydrous ethanol and acetone in sequence (5-10 min), and then dried (100-150°C) to obtain a clean nitrided workpiece.

[0118] (4) Magnetron sputtering

[0119] Turn on the power of the coating equipment, turn on the power of the water chiller, turn on the pressure relief valve, and ensure that the pressure in the coating equipment is at the twelfth stage pressure (9.8 x 10 4 ~1 x 10 5 Pa), open the vacuum chamber door, and hang the workpiece treated in the above steps on the rotating stand.

[0120] Close the vacuum chamber door, turn off the pressure relief valve, turn on the mechanical pump, turn on the roughing valve, and pump the equipment to the thirteenth stage pressure (1 x 10 1 ~5 x 10 1 ), turn off the roughing valve, turn on the front stage valve, the maintenance valve, and the molecular pump. Wait until the power frequency of the molecular pump reaches (300-400 Hz) and the ionization gauge is lit, turn on the high valve, connect the front stage and the box, and continue to pump to the fourteenth stage pressure (0-1 x 10 -3 Pa).

[0121] Set the seventh stage temperature (250-350°C), open the gas cylinder, slowly introduce inert gas, and make the coating equipment reach the fifteenth stage pressure (3 x 10 -1 ~5 x 10 -1 Pa), and set the fifth stage bias (300-500 Pa). Sputter clean the surface of the workpiece for 20-30 minutes.

[0122] After cleaning, close the forevacuum valve, open the roughing valve, and slowly continue to increase the temperature to the eighth stage temperature (350-450°C), slowly introduce the nitriding gas, and make the plating equipment reach the sixteenth stage gas pressure (0-1 x 10 1 Pa), and start the second stage nitriding treatment for 5-10 min. The nitriding gas is ammonia.

[0123] Deposition of a Cr layer: after the second stage nitriding treatment is completed, stop the introduction of the nitriding gas, close the roughing valve, open the forevacuum valve, and start slowly introducing the plating gas, so that the plating equipment is maintained at the seventeenth stage gas pressure (5 x 10 -1 -5 x 10 0 Pa). Set the target arc current (60-90 A), set the sixth stage bias voltage (500-800 V), open three Cr targets, and deposit for 1-5 min.

[0124] Deposition of a CrN layer: set the seventh stage bias voltage (100-200 V), set the target current (60-90 A), slowly introduce the gas containing N element, and maintain the plating equipment at the eighteenth stage gas pressure (5 x 10 -1 -5 x 10 0 Pa), and deposit (30-90 min). The gas containing N element is nitrogen.

[0125] Deposition of a CrAlSiN layer: open one Al-Si alloy target, set four target currents (70-90 A), set the eighth stage bias voltage (100-200 V), maintain the gas pressure in the equipment at the nineteenth stage gas pressure (1 x 10 -1 -5 x 10 0 Pa), and deposit for 60-90 min.

[0126] Deposition of a CrAlTiSiN layer: 1) close the Al-Si alloy target and one Cr target, and open one Al-Ti-Si alloy target, maintain the plating equipment at the twentieth stage gas pressure (1 x 10 0 -5 x 10 0 Pa), set the target current (30-60 A), set the ninth stage bias voltage (200-300 V), and deposit for 5-10 min; 2) increase the Al-Ti-Si alloy target current to (60-80 A), and open one Al-Ti alloy target, set the Al-Ti alloy target current to (50-70 A), set the two Cr target currents to (30-60 A), and deposit for 0.1-1 min; 3) keep the Cr target and Al-Ti-Si alloy target currents unchanged, and reduce the Al-Ti target current to (20-40 A), and deposit for 0.1-1 min; then steps 2) and 3) are alternately performed 10-50 times.

[0127] 4) After the completion of the alternate deposition, the equipment is maintained at the twenty-first stage air pressure (1x10 0 ~ 5x10 0 Pa), 3 Cr targets, 1 Al-Ti-Si alloy target and 1 Al-Ti alloy target are turned on, the current of each target is set to 70~90A, the tenth stage bias voltage (100~200V) is set, and deposition is performed for 0.1~1min; 5) After the completion of the deposition, 1 Cr target is turned off, and other parameters remain unchanged, deposition is performed for 1~1.5min, and then the above steps 4) and 5) are alternately repeated with a modulation period of 30~50nm until the number of deposited layers is 30~50 layers; 6) After the completion of the alternate deposition, the eleventh stage bias voltage (100~200V) is set, 3 Cr targets, 1 Al-Ti-Si alloy target and 1 Al-Ti alloy target are turned on, the current of each target is set to 70~90A, and deposition is performed for 1~2min; 7) After the completion of the deposition, the twelfth stage bias voltage (100~200V) is set, 1 Cr target is turned off, and other parameters remain unchanged, and deposition is performed for 1~2min.

[0128] Deposition of CrWAlTiN layer and WCrAlTiN layer: the Al-Ti-Si alloy target is turned off, 2 W targets, 1 Cr target and 3 Al-Ti alloy targets are turned on based on the previous step, the equipment is maintained at the twenty-second stage air pressure (1x10 0 ~ 3x10 0 Pa), the current of each target is set to 60~90A, and the thirteenth stage bias voltage (200~300V) is set; then 1 Cr target is turned off and 1 W target is turned on, the equipment is maintained at the twenty-third stage air pressure (1x10 0 ~ 3x10 0 Pa), the current of each target is set to 60~90A, and the fourteenth stage bias voltage (200~300V) is set, and deposition is performed for 60~120min; the W target and the Cr target are alternately deposited for 40~50 layers with a modulation period of 30~50nm.

[0129] After the deposition is completed, all targets are turned off, the bias voltage is turned off, the heating is stopped, the gas containing N element is continuously introduced, and the equipment is maintained at the twenty-fourth stage air pressure (1x10 -3 ~ 5x10 -1 Pa). After the temperature in the coating equipment reaches the ninth stage temperature (25~50℃), the introduction of the gas containing N element is stopped, the gas cylinder is closed, the high valve is closed, the fore pump is closed, the mechanical pump is opened, the pressure relief valve is opened, the vacuum chamber is opened, and the workpiece is taken out. The vacuum chamber door is closed, the pressure relief valve is closed, the mechanical pump is opened, and the equipment is pumped to the twenty-fifth stage air pressure (1x10 1 ~ 5x10 1Open the pre-stage valve, open the high-pressure valve, connect the pre-stage and the housing, and continue evacuating to the twenty-sixth stage pressure (0~1×10). -3 (Pa). Close the high-pressure valve, turn off the molecular pump, close the holding valve, close the fore-stage valve, turn off the mechanical pump, and turn off the power supply.

[0130] The present invention also provides a stainless steel composite material, which is prepared by the preparation method described above.

[0131] Specifically, such as Figure 3 As shown, the stainless steel composite material includes a stainless steel substrate 1, a nitriding layer 2 disposed on the surface of the stainless steel substrate, and a WCrAlSiTiN coating 3 disposed on the side of the nitriding layer 2 away from the stainless steel substrate 1.

[0132] In some embodiments of this application, the WCrAlSiTiN coating 3 includes a Cr layer, a CrN layer, a CrAlSiN layer, a CrAlTiSiN layer and an alternately stacked CrWAlTiN layer and a WCrAlTiN layer (not shown in the figure) deposited sequentially on the nitrided layer. In the CrWAlTiN layer, the Cr content is greater than the W content, and in the WCrAlTiN layer, the Cr content is less than the W content.

[0133] In some embodiments of this application, the CrAlTiSiN layer is a multilayer structure. Along the direction away from the nitriding layer, the multilayer structure includes at least one first sublayer, M alternating layers of second and third sublayers, N alternating layers of fourth and fifth sublayers, at least one sixth sublayer, and at least one seventh sublayer. The content of Al and Ti elements in the second sublayer is greater than the content of Al and Ti elements in the first and third sublayers, and the content of Cr element in the fourth sublayer is greater than the content of Cr element in the fifth sublayer.

[0134] In some embodiments of this application, 10≤M≤50, 15≤N≤25.

[0135] In some embodiments of this application, the number of alternating stacking cycles of the CrWAlTiN layer and the WCrAlTiN layer is 20 to 25.

[0136] The stainless steel composite material of this application includes all the effective effects of the preparation methods provided by any of the above technical solutions, and will not be repeated here to avoid repetition.

[0137] It should be noted that the above description of stainless steel composite materials is similar to the description of the above method embodiments. For technical details not disclosed in the stainless steel composite material embodiments of this application, please refer to the description of the method embodiments of this application for understanding.

[0138] Example 1

[0139] A 2Cr13 martensitic stainless steel bar was cut to obtain a pretreated sample; the above treated 2Cr13 martensitic stainless steel workpiece was ground and polished to obtain a clean surface workpiece. The 2Cr13 martensitic stainless steel after the above steps was cleaned twice by ultrasonic cleaning with acetone and alcohol, and finally dried.

[0140] Turn on the power supply of the nitriding equipment, open the pressure relief valve, and ensure that the vacuum chamber is at the first stage gas pressure 1x10 5 Pa. Turn on the furnace shell of the ion nitriding equipment, and put the workpiece after the above steps into the vacuum chamber, and close the furnace shell. Close the pressure relief valve, and open the mechanical pump to draw the vacuum chamber to the second stage gas pressure 3x10 1 Pa. Turn on the high voltage switch, turn on the temperature switch, set the nitriding temperature to 480℃, wait for the nitriding equipment to rise to the first stage temperature 100℃, set the first stage bias voltage to 600V, and slowly rise to the first stage duty ratio 15%. Wait for the nitriding equipment to run stably, set the second stage bias voltage to 650V, slowly rise to the second stage duty ratio 30%, wait for the nitriding equipment to stabilize, slowly rise to the third stage duty ratio 52%, wait for the nitriding equipment to stabilize, slowly rise to the fourth stage duty ratio 73%, and wait for the nitriding equipment to stabilize. Turn on the gas cylinder switch, and introduce ammonia gas. Adjust the nitriding equipment to reach the third stage gas pressure 5x10 1 Pa, and clean the surface for 20 minutes. After cleaning, continue to introduce ammonia gas, and slowly raise the gas pressure of the nitriding equipment to the fourth stage gas pressure 1x10 2 Pa. Wait for the nitriding equipment to reach the second stage temperature 100, increase the flow rate of ammonia gas, and raise the gas pressure in the nitriding equipment to the fifth stage gas pressure 1.5x10 2 Pa. Wait for the nitriding equipment to reach the third stage temperature 250℃, increase the flow rate of ammonia gas, and raise the gas pressure in the nitriding equipment to the sixth stage gas pressure 2x10 2 Pa. Wait for the nitriding equipment to reach the fourth stage temperature 300℃, open the circulating cooling water, increase the flow rate of ammonia gas, and raise the gas pressure in the nitriding equipment to the seventh stage gas pressure 2.5x10 2 Pa. Wait for the nitriding equipment to reach the fifth stage temperature 400℃, increase the flow rate of ammonia gas, and raise the gas pressure in the nitriding equipment to the eighth stage gas pressure 3x10 2 Pa, and set the fourth stage bias voltage to 750V. Wait for the nitriding equipment to reach the nitriding temperature, and start the holding for 5h. After the holding time, continue to introduce ammonia gas, and adjust the gas pressure in the nitriding equipment to the ninth stage gas pressure 3x10 1Pa, the duty cycle and bias voltage slowly to 0, turn off the high voltage switch, turn off the temperature switch. Wait for the nitriding equipment temperature to reach the sixth stage temperature 50℃, stop the ammonia gas, close the cylinder, close the mechanical pump, open the pressure relief valve, wait for the pressure in the nitriding equipment to reach the tenth stage pressure 1 x 10 5 Pa. Open the nitriding equipment furnace shell, take out the nitriding workpiece. Close the furnace shell, close the pressure relief valve, open the vacuum pump, so that the nitriding equipment is in the eleventh stage pressure 1 x 10 1 Pa. Turn off the mechanical pump, turn off the power of the nitriding equipment.

[0141] The above-mentioned martensitic stainless steel workpiece is pickled with nitric acid-hydrofluoric acid for 1 min, ultrasonically cleaned with alcohol for 5 min, and dried at 120℃ to obtain a clean nitriding workpiece.

[0142] Turn on the power of the coating equipment, turn on the power of the water chiller, open the pressure relief valve, and ensure that the pressure in the coating equipment is in the twelfth stage pressure 1 x 10 5 Pa, open the vacuum chamber door, and hang the workpiece treated in the above steps on the rotating frame. Close the vacuum chamber door, close the pressure relief valve, open the mechanical pump, open the roughing valve, and pump the equipment to the thirteenth stage pressure 3 x 10 1 , close the roughing valve, open the pre-stage valve, maintenance valve and molecular pump. Wait for the power frequency of the molecular pump to reach 400Hz, and the ionization gauge to light up, open the high valve, connect the pre-stage and the box, and continue to pump to the fourteenth stage pressure 1 x 10 -3 Pa.

[0143] Set the seventh stage temperature to 350℃, open the cylinder, slowly introduce argon, so that the pressure in the coating equipment reaches the fifteenth stage pressure 3 x 10 -1 Pa, set the fifth stage bias voltage to 500Pa. Sputter clean the surface of the workpiece for 20 minutes. After cleaning, close the pre-stage valve, open the roughing valve, slowly continue to heat to the eighth stage temperature 450℃, slowly introduce ammonia, so that the pressure in the coating equipment reaches the sixteenth stage pressure 1 x 10 1 Pa, start the second stage nitriding treatment for 5-10min. After the second stage nitriding treatment is completed, stop the ammonia gas, and maintain the pressure in the coating equipment at the seventeenth stage pressure 2 x 10 0 Pa. Set the target arc current to 70A, set the sixth stage bias voltage to 800V, open 3 Cr targets, and deposit for 4min.

[0144] Set the seventh stage bias voltage to 140V, set the target current to 80A, start slowly introducing nitrogen, and maintain the pressure in the coating equipment at the eighteenth stage pressure 3 x 10 0 Pa, deposit for 70min.

[0145] Open 1 Al-Si alloy target, set 4 target currents to 80 A, set eighth stage bias voltage to 130 V, maintain the pressure in the equipment at the nineteenth stage pressure of 4 x 10 0 Pa, deposit for 75 min.

[0146] Close 1 Cr target, open 1 Al-Ti-Si alloy target, maintain the coating equipment at the twentieth stage pressure of 1.5 x 10 0 Pa, set each target current to 55 A, set ninth stage bias voltage to 200 V, deposit for 5 min, increase the Al-Ti-Si alloy target current to 75 A, open 1 Al-Ti alloy target, set the Al-Ti alloy target current to 60 A, set 2 Cr target currents to 55 A, deposit for 0.6 min. Keep the Cr target and the Al-Ti-Si alloy target currents unchanged, reduce the Al-Ti target current to 35 A, deposit for 0.8 min. Keep other target currents unchanged, only change the Al-Ti alloy target current, repeat the above alternating deposition for a total of 30 layers.

[0147] After deposition, maintain the equipment at the twenty-first stage pressure of 4 x 10 0 Pa, open 3 Cr targets, 1 Al-Ti-Si alloy target and 1 Al-Ti alloy target, set each target current to 80 A, set tenth stage bias voltage to 150 V, deposit for 0.8 min. After deposition, close 1 Cr target, keep other parameters unchanged, deposit for 1.1 min. Repeat the above steps alternately until the number of deposited layers is 43 layers, then open 3 Cr targets, 1 Al-Ti-Si alloy target and 1 Al-Ti alloy target, set each target current to 80 A, set eleventh stage bias voltage to 160 V, deposit for 1 min; then, close one Cr target, keep other parameters unchanged, set twelfth stage bias voltage to 160 V, deposit for 1 min.

[0148] Close the Al-Ti-Si alloy target, open 2 W targets, 1 Cr target and 3 Al-Ti alloy targets, maintain the equipment at the twenty-second stage pressure of 1.5 x 10 0 Pa, set each target current to 75 A, set thirteenth stage bias voltage to 250 V; close one Cr target and open another W target, maintain the equipment at the twenty-third stage pressure of 1.5 x 10 0 Pa, set each target current to 75 A, set fourteenth stage bias voltage to 150 V, deposit for 100 min; repeat the above alternating deposition of W target and Cr target for 50 layers, with a modulation period of 30 nm.

[0149] After deposition, close all targets, close the bias voltage, stop heating, continue to introduce nitrogen, and maintain the equipment at the twenty-fourth stage pressure of 5 x 10 -2Pa. Wait for the ninth stage temperature 50℃ in the coating equipment to reach, stop the nitrogen inlet, close the cylinder, close the high valve, close the front stage valve, close the mechanical pump, open the pressure relief valve, open the vacuum chamber, take out the workpiece. Close the vacuum chamber door, close the pressure relief valve, open the mechanical pump, and the equipment is pumped to the second twenty-five stage gas pressure 1x10 1 Pa. Open the front stage valve, open the high valve, connect the front stage and the box, continue to pump to the second twenty-six stage gas pressure 1x10 -3 Pa. Close the high valve, close the molecular pump, close the maintenance valve, close the front stage valve, close the mechanical pump, and close the power supply.

[0150] Example 2

[0151] The 2Cr13 martensitic stainless steel bar was cut to obtain a pretreated sample; the treated 2Cr13 martensitic stainless steel workpiece was ground and polished to obtain a clean surface workpiece. The 2Cr13 martensitic stainless steel after the above steps was cleaned twice by ultrasonic cleaning with acetone and alcohol, and finally blow-dried.

[0152] Turn on the power supply of the nitriding equipment, open the pressure relief valve, and ensure that the vacuum chamber is at the first stage gas pressure 1x10 5 Pa. Open the furnace shell of the ion nitriding equipment, put the workpiece after the above steps into the vacuum chamber, and close the furnace shell. Close the pressure relief valve, open the mechanical pump, and pump the vacuum chamber to the second stage gas pressure 3x10 1 Pa. Open the high voltage switch, open the temperature switch, set the nitriding temperature to 440℃, wait for the nitriding equipment to rise to the first stage temperature 100℃, set the first stage bias voltage to 600V, and slowly rise to the first stage duty ratio 15%. Wait for the nitriding equipment to run stably, set the second stage bias voltage to 650V, slowly rise to the second stage duty ratio 30%, slowly rise to the third stage duty ratio 52% after the nitriding equipment is stable, slowly rise to the fourth stage duty ratio 73% after the nitriding equipment is stable, open the cylinder switch, and introduce ammonia. Adjust the nitriding equipment to reach the third stage gas pressure 5x10 1 Pa, and clean the surface for 20 minutes. After cleaning, continue to introduce ammonia, slowly increase the gas pressure of the nitriding equipment to the fourth stage gas pressure 1x10 2 Pa. Wait for the nitriding equipment to reach the second stage temperature 100, increase the flow of ammonia, and increase the gas pressure in the nitriding equipment to the fifth stage gas pressure 1.5x10 2 Pa. Wait for the nitriding equipment to reach the third stage temperature 250℃, open the circulating cooling water, increase the flow of ammonia, and increase the gas pressure in the nitriding equipment to the sixth stage gas pressure 2x10 2 Pa. Wait for the nitriding equipment to reach the fourth stage temperature 300℃, open the circulating cooling water, increase the flow of ammonia, and increase the gas pressure in the nitriding equipment to the seventh stage gas pressure 2.5x102 Pa. Wait for the nitriding equipment to reach the fifth stage temperature 400℃, increase the flow of ammonia, and raise the pressure in the nitriding equipment to the eighth stage pressure 3x10 2 Pa, and set the fourth stage bias 750V. After waiting for the nitriding equipment to reach the nitriding temperature, start the 5h holding time. After the holding time, continue to pass ammonia, adjust the pressure in the nitriding equipment to the ninth stage pressure 3x10 1 Pa, slowly adjust the duty ratio and bias to 0, turn off the high voltage switch, and turn off the temperature switch. Wait for the temperature in the nitriding equipment to reach the sixth stage temperature 50℃, stop passing ammonia, close the gas cylinder, close the mechanical pump, open the pressure relief valve, and wait for the pressure in the nitriding equipment to reach the tenth stage pressure 1x10 5 Pa. Open the nitriding equipment furnace shell and take out the nitrided workpiece. Close the furnace shell, close the pressure relief valve, and open the vacuum pump to make the pressure in the nitriding equipment reach the eleventh stage pressure 1x10 1 Pa. Turn off the mechanical pump and turn off the power of the nitriding equipment.

[0153] The above-processed martensitic stainless steel workpiece is pickled with nitric acid-hydrofluoric acid for 1 min, ultrasonically cleaned with anhydrous ethanol for 5 min, and dried at 120℃ to obtain a clean nitrided workpiece.

[0154] Turn on the power of the coating equipment, turn on the power of the water chiller, open the pressure relief valve, and ensure that the pressure in the coating equipment is at the twelfth stage pressure 1x10 5 Pa, open the vacuum chamber door, and hang the workpiece processed in the above steps on the rotating stand. Close the vacuum chamber door, close the pressure relief valve, open the mechanical pump, open the roughing valve, and pump the equipment to the thirteenth stage pressure 3x10 1 , close the roughing valve, open the pre-stage valve, maintenance valve, and molecular pump. Wait for the power frequency of the molecular pump to reach 400Hz and the ionization gauge to light up, open the high valve, connect the pre-stage and the box, and continue to pump to the fourteenth stage pressure 1x10 -3 Pa.

[0155] Set the seventh stage temperature 350℃, open the gas cylinder, slowly pass in argon, and make the pressure in the coating equipment reach the fifteenth stage pressure 3x10 -1 Pa, and set the fifth stage bias 500Pa. Sputter clean the surface of the workpiece for 20 minutes. After cleaning, close the pre-stage valve, open the roughing valve, slowly continue to heat to the eighth stage temperature 450℃, slowly pass in ammonia, and make the pressure in the coating equipment reach the sixteenth stage pressure 1x10 1 Pa, and start the second stage nitriding treatment for 5-10min. After the second stage nitriding treatment is completed, stop passing ammonia and maintain the pressure in the coating equipment at the seventeenth stage pressure 2x10 0Pa. Set target arc current 70 A, set sixth stage bias 800 V, open 3 Cr targets, deposition time 4 min.

[0156] Set seventh stage bias 140 V, set target current 80 A, start slow nitrogen gas flow, maintain the coating equipment at eighteenth stage gas pressure 3 x 10 0 Pa, deposition 70 min.

[0157] Open 1 Al-Si alloy target, set 4 target currents to 80 A, set eighth stage bias 130 V, maintain the equipment at nineteenth stage gas pressure 4 x 10 0 Pa, deposition 75 min.

[0158] Close 1 Cr target, open 1 Al-Ti-Si alloy target, maintain the coating equipment at twentieth stage gas pressure 1.5 x 10 0 Pa, set each target current to 55 A, set ninth stage bias 200 V, deposition 5 min, increase the Al-Ti-Si alloy target current to 75 A, open 1 Al-Ti alloy target, set the Al-Ti alloy target current to 60 A, set 2 Cr target currents to 55 A, deposition 0.6 min. Keep the Cr target and Al-Ti-Si alloy target currents unchanged, reduce the Al-Ti target current to 35 A, deposition 0.8 min. Keep other target currents unchanged, only change the Al-Ti alloy target current, repeat the above steps for 30 layers.

[0159] After deposition, maintain the equipment at twenty-first stage gas pressure 4 x 10 0 Pa, open 3 Cr targets, 1 Al-Ti-Si alloy target and 1 Al-Ti alloy target, set each target current to 80 A, set tenth stage bias 150 V, deposition 0.8 min. After deposition, close 1 Cr target, keep other parameters unchanged, deposition 1.1 min. Repeat the above steps with a modulation period of 35 nm, until the number of deposited layers is 43, then open 3 Cr targets, 1 Al-Ti-Si alloy target and 1 Al-Ti alloy target, set each target current to 80 A, set eleventh stage bias 160 V, deposition time 1 min; close one Cr target, keep other parameters unchanged, set twelfth stage bias 160 V, deposition time 1 min.

[0160] Close the Al-Ti-Si alloy target, open 2 W targets, 1 Cr target and 3 Al-Ti alloy targets, maintain the equipment at twenty-second stage gas pressure 1.5 x 10 0 Pa, set each target current to 75 A, set thirteenth stage bias 250 V; close one Cr target, and open another W target, maintain the equipment at twenty-third stage gas pressure 1.5 x 100 Pa, the current of each target was set to 75 A, the fourteenth stage bias was set to 150 V, and deposition was performed for 100 min; the W target and the Cr target were alternately deposited for a total of 50 layers, and the modulation period was 30 nm.

[0161] After the deposition was completed, all the targets were turned off, the bias was turned off, the heating was stopped, the nitrogen gas was continuously supplied, and the equipment was maintained at the twenty-fourth stage gas pressure of 5x10 -2 Pa. The ninth stage temperature of 50°C was waited to be reached in the coating equipment, the nitrogen gas was stopped, the gas cylinder was turned off, the high valve was turned off, the fore pump was turned off, the mechanical pump was turned off, the pressure relief valve was turned on, the vacuum chamber was opened, and the workpiece was taken out. The vacuum chamber door was closed, the pressure relief valve was turned off, the mechanical pump was turned on, the equipment was pumped to the twenty-fifth stage gas pressure of 1x10 1 Pa, the fore valve was turned on, the high valve was turned on, the fore and the tank were connected, and vacuum pumping was continuously performed to the twenty-sixth stage gas pressure of 1x10 -3 Pa. The high valve was turned off, the molecular pump was turned off, the maintenance valve was turned off, the fore valve was turned off, the mechanical pump was turned off, and the power was turned off.

[0162] Comparative Example 1

[0163] The stainless steel composite material was prepared according to the method of Example 1, except that the acid pickling was not followed by the magnetron sputtering treatment.

[0164] Comparative Example 2

[0165] The stainless steel composite material was prepared according to the method of Example 2, except that the acid pickling was not followed by the magnetron sputtering treatment.

[0166] Comparative Example 3

[0167] The stainless steel composite material was prepared according to the method of Example 1, except that the 2Cr13 martensitic stainless steel rod was directly subjected to the magnetron sputtering after the cutting, grinding, polishing, ultrasonic cleaning and blow-drying treatment, and was not subjected to the first nitriding treatment and the acid pickling treatment.

[0168] Performance test of the stainless steel composite materials prepared in Examples 1 and 2 and Comparative Examples 1-3

[0169] Figure 4 The XRD patterns of the prepared stainless steel composite materials. For comparison, the untreated 2Cr13 martensitic stainless steel rod was also used as a comparison, wherein Untreaed represents the untreated sample, HPN+C represents the sample obtained in Example 1, LPN+C represents the sample obtained in Example 2, HPN represents the sample obtained in Comparative Example 1, LPN represents the sample obtained in Comparative Example 2, and Coating represents the sample obtained in Comparative Example 3.

[0170] The Untreaed sample mainly consists of α-Fe phase. The Coating sample has CrN phase, W2N phase, TiN phase and AlN phase in addition to the phases contained in the Untreaed sample. The LPN sample has ε-Fe 2-3 N phase, γ'-Fe4N phase and α N phase as the dominant diffraction peaks. The existence of α N phase can make the sample have higher hardness and good corrosion resistance. As for the HPN sample, in addition to the phases contained in the low-temperature nitriding sample, a small amount of CrN phase is precipitated. 2-3 N

[0171] Figure 5 The figures are cross-sectional morphology of different samples under optical microscope. It can be seen from the cross-sectional morphology of the Coating sample that a thin, uniform and dense coating is deposited on the surface of the substrate. By comparing the cross-sections of the LPN sample and the HPN sample, it can be found that the thickness of the compound on the surface of the sample and the diffusion layer increases with the increase of temperature. It can be found from the cross-sectional morphology of the LPN+C sample and the HPN+C sample that the cross-section of the sample is composed of a thick nitride layer and a thin coating layer, and there is an obvious boundary between the nitride layer and the coating layer.

[0172] Figure 6 The figures are hardness values of the prepared stainless steel composite materials, wherein the hardness values are measured by Vickers hardness tester. It can be seen that the surface hardness of the substrate is only 223HV 0.1 , and the surface hardness of the LPN and the HPN reaches 1284HV 0.1 and 1087HV 0.1 , respectively, which is nearly 6 times of the original substrate. The surface hardness of the Coating sample is about 526HV 0.1 , which is only 2.4 times of the original sample. The surface microhardness of the LPN+C sample and the HPN+C sample is about 2064HV 0.1 and 2111HV 0.1 , respectively, which is about 10 times of the original substrate. This is because the sample treated by nitriding has a thicker and denser nitride layer, and the higher surface hardness gives the coating better support, so that the hardness of the coating can be realized.

[0173] The cross-sectional hardness gradient analysis of the LPN, HPN, LPN+C and HPN+C samples is carried out by applying a load of 100g, as shown in the figure. Figure 7 The results show that the thickness of the nitride layer of the HPN sample and the LPN sample is about 194.013 μm and 93.375 μm, respectively.​​

[0174] Figure 8 The polarization curves of the different samples in the seawater solution for the electrochemical corrosion test, the untreated sample has a lower self-corrosion potential, a higher self-corrosion current density and a corrosion rate, and the corrosion resistance of the untreated sample is poor. The polarization curve of the LPN sample moves to the positive electrode, but the corrosion current density and the corrosion rate increase. The polarization curve of the HPN sample presents a wide passivation zone, compared with the untreated sample, the self-corrosion potential moves to the negative electrode, the corrosion current density increases, the corrosion rate increases, and the corrosion resistance decreases, which may be due to the precipitation of CrN under high temperature conditions. The polarization curve of the coating sample does not present obvious passivation phenomenon, the self-corrosion potential moves to the anode, the corrosion current density and the corrosion rate decrease, and excellent corrosion resistance is presented. The self-corrosion potential of the LPN+C sample increases, the corrosion current density and the corrosion rate decrease, and excellent corrosion performance is presented. The self-corrosion potential of the HPN+C sample increases compared with the untreated sample and the HPN sample, the corrosion current density and the corrosion rate decrease, and the corrosion resistance is improved.

[0175] Figure 9 The surface morphology of the different samples after the electrochemical corrosion is observed by an optical microscope (500 times). The corrosion resistance of the untreated sample is the worst, and the surface has been corroded to form multiple dense and obvious pits. The surface of the coating sample presents long strip-shaped corrosion gullies, and part of the coating has been dissolved, and this phenomenon is mainly due to the corrosion phenomenon caused by the invasion of Cl- into the defects on the surface of the coating. The LPN sample presents a better corrosion morphology, and only shallow point-shaped corrosion pits appear on the surface of the sample. Although the number of the corrosion pits of the HPN sample is less than that of the LPN sample, the diffusion degree of the corrosion medium is deeper. The HPN+C and LPN+C samples present good corrosion resistance, and the pits are small and shallow, which indicates that the coating can well protect the substrate. The corrosion pits are relatively dense, which may be due to the corrosion of the coating deposited on the surface at the defect position, and the point corrosion phenomenon appears, but the existence of the nitriding layer effectively prevents the diffusion of the corrosion medium and the charge transfer in the coating, and reduces the corrosion current density and the corrosion rate.

[0176] Figure 10 The EIS graphs of the different samples in the seawater solution for the electrochemical corrosion test, the untreated sample presents a single capacitance arc characteristic, the capacitance arc radius of the samples treated increases, which indicates that the impedance increases, the corrosion rate decreases, and the corrosion resistance increases. Among them, the capacitance arc radius of the LPN+C sample is the largest, the corrosion resistance is the best, and the corrosion resistance of the coating sample is the second.

[0177] From the above technical solutions, the advantages and positive effects of the present application are that:

[0178] The stainless steel composite material obtained by the preparation method can effectively improve the comprehensive performance of the surface of the martensitic stainless steel, including mechanical properties, wear resistance and corrosion resistance; the nitriding layer can not only improve the corrosion resistance and wear resistance of the stainless steel substrate, but also can improve the hardness matching of the stainless steel substrate and the WCrAlSiTiN coating by improving the strength of the stainless steel substrate, so as to improve the bonding strength of the coating and the stainless steel substrate, ensure the service life of the coating, and further improve the hardness, wear resistance and corrosion resistance of the stainless steel through the deposited WCrAlSiTiN coating, and the hardness can reach 2000HV 0.1 The above has a low self-corrosion current density, prolongs the service life of the instrument and equipment using stainless steel as the material in the high-salt and high-humidity environment such as the sea, and the coating structure deposited on the whole stainless steel surface is simple and convenient to operate.

[0179] Although the present application has been described with reference to several exemplary embodiments, it is understood that the words that have been used are words of description and illustration, rather than words of limitation. Since the present application can be embodied in various forms without departing from the spirit or essential characteristics thereof, it is understood that the embodiments are not limited to any particular details, but are to be interpreted broadly within the spirit and scope of the appended claims, and therefore all changes and modifications that fall within the criteria of the patent are therefore to be embraced by the appended claims.

Claims

1. A method for producing a stainless steel composite material, characterized by, The method comprises the following steps: a first nitriding treatment is performed on a stainless steel base to form a nitriding layer on the surface of the stainless steel base; the stainless steel base with the nitriding layer is subjected to pickling, and then cleaned and dried; a magnetron sputtering is performed on the stainless steel base after the pickling treatment to sequentially deposit a Cr layer, a CrN layer, a CrAlSiN layer, a CrAlTiSiN layer, a CrWAlTiN layer and a WCrAlTiN layer on the surface of the nitriding layer to form a WCrAlSiTiN coating layer, wherein the step of depositing the CrWAlTiN layer and the step of depositing the WCrAlTiN layer are alternately performed for a preset number of times; the step of depositing the CrAlTiSiN layer specifically comprises: step 1: continue to introduce nitrogen into the sputtering cavity, and simultaneously turn on the Cr target and the AlTiSi target to deposit a first sublayer, the current of the Cr target and the AlTiSi target is 30A-60A, the negative bias voltage is 200V-300V, and the deposition time is 5min-10min; step 2: continue to introduce nitrogen into the sputtering cavity, and simultaneously turn on the Cr target, the AlTiSi target and the AlTi target to deposit a second sublayer, the current of the Cr target is 30A-60A, the current of the Al-Ti-Si target is 60A-80A, the current of the Al-Ti target is 50A-70A, the negative bias voltage is 200V-300V, and the deposition time is 0.1min-1min; step 3: on the basis of step 2, the current of the AlTi target is reduced to 20A-40A, and the current of the other targets remains unchanged, a third sublayer is deposited under a negative bias voltage of 200V-300V, and the deposition time is 0.1min-1min; the step 2 and the step 3 are alternately performed for a preset number of times; step 4: continue to introduce nitrogen into the sputtering cavity, and simultaneously turn on the Cr target, the Al-Ti-Si target and the Al-Ti target to deposit a fourth sublayer, the current of each target is 70A-90A, the negative bias voltage is 100V-200V, and the deposition time is 0.1min-1min; step 5: on the basis of step 4, the number of the Cr target turned on is reduced, the current of each target remains unchanged, a fifth sublayer is deposited under a negative bias voltage of 100V-200V, and the deposition time is 0.1min-1min; the step 4 and the step 5 are alternately performed for a preset number of times; step 6: on the basis of step 4, the deposition time is set to 1min-2min, and a sixth sublayer is deposited; step 7: on the basis of step 5, the deposition time is set to 1min-2min, and a seventh sublayer is deposited.

2. The production method according to claim 1, characterized by, The nitriding temperature of the first nitriding treatment is 350℃-480℃; and the nitriding gas of the first nitriding treatment is ammonia.

3. The preparation method according to claim 1, characterized in that, the pickling of the stainless steel base with the nitriding layer, and then cleaning and drying, comprises: the stainless steel base with the nitriding layer is immersed in an acidic solution for 1min-2min, and then ultrasonic cleaned with anhydrous ethanol and / or acetone for 5min-10min, and then dried at 100-150℃; the acidic solution is a mixed solution of nitric acid and hydrofluoric acid.

4. The preparation method according to claim 1, characterized in that, The step of depositing the CrWAlTiN layer and the step of depositing the WCrAlTiN layer are alternately performed for a preset number of times, comprising: depositing the CrWAlTiN layer: continuing to introduce nitrogen into the sputtering cavity, while turning on the W target, the Cr target and the AlTi target, the current of each target being 60A-90A, the negative bias being 200V-300V, and the deposition time being 60min-120min, wherein the number of the Cr target turned on is greater than the number of the W target; depositing the WCrAlTiN layer: continuing to introduce nitrogen into the sputtering cavity, while turning on the W target, the Cr target and the AlTi target, the current of each target being 60A-90A, the negative bias being 200V-300V, and the deposition time being 60min-120min, wherein the number of the Cr target turned on is less than the number of the W target; The step of depositing the CrWAlTiN layer and the step of depositing the WCrAlTiN layer are alternately performed for a preset number of times.

5. The preparation method according to claim 4, characterized in that, Before depositing the Cr layer on the nitriding layer, further comprising: introducing nitriding gas into the sputtering cavity to perform a second nitriding treatment on the stainless steel substrate formed with the nitriding layer; the nitriding temperature of the second nitriding treatment is 350-480℃; the nitriding gas of the second nitriding treatment is ammonia; and the nitriding time of the second nitriding treatment is 5-10min.

6. A stainless steel composite material, characterized by, comprising: a stainless steel substrate; a nitriding layer arranged on the surface of the stainless steel substrate; and a WCrAlSiTiN coating arranged on the side of the nitriding layer away from the stainless steel substrate; the WCrAlSiTiN coating comprises a Cr layer, a CrN layer, a CrAlSiN layer, a CrAlTiSiN layer and alternately stacked CrWAlTiN layers and WCrAlTiN layers deposited on the nitriding layer in sequence, wherein the content of Cr in the CrWAlTiN layer is greater than the content of W, and the content of Cr in the WCrAlTiN layer is less than the content of W; the CrAlTiSiN layer has a multilayer structure, along the direction away from the nitriding layer, the multilayer structure comprises at least one first sublayer, M cycles of alternately stacked second sublayers and third sublayers, N cycles of alternately stacked fourth sublayers and fifth sublayers, at least one sixth sublayer and at least one seventh sublayer, the content of Al and Ti in the second sublayer is greater than the content of Al and Ti in the first sublayer and the third sublayer, and the content of Cr in the fourth sublayer is greater than the content of Cr in the fifth sublayer.

7. The stainless steel composite of claim 6, wherein, 10≤M≤50, 15≤N≤25; and / or, the number of cycles of alternately stacking the CrWAlTiN layers and the WCrAlTiN layers is 20-25.

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