Nickel-chromium coated tin bronze self-lubricating composite coating and method for preparing the same

Abstract

The application discloses a nickel-chromium coated tin bronze self-lubricating composite coating and a preparation method thereof. Tin bronze powder is placed in a chemical plating chromium solution, and is kept at 70-90 DEG C for 110-130 min to obtain a chemical plating composite powder. The nickel-chromium coated tin bronze self-lubricating composite coating is sprayed on the surface of an alloy base by using a wide-speed-range high-energy plasma spraying method. The self-lubricating composite coating prepared by the application has a NiCr alloy phase dispersedly distributed in the structure, and a Cr-rich phase is dispersed in the coating in the form of a small unit with a diameter of 1 micrometer, which serves as a dispersion strengthening phase, promotes the increase of the slip resistance of plastic deformation of the coating, and improves the mechanical strength of the coating. The introduced Ni and Cr react with the tin bronze during the spraying process to generate a new alloy phase, changes the regular layered arrangement of metal atoms, makes the relative sliding between the atom layers difficult, and is beneficial to improving the mechanical strength and fracture toughness of the coating.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of surface engineering and technology, in particular to a nickel-chromium coated tin bronze self-lubricating composite coating and a preparation method thereof. BACKGROUND

[0002] Energy consumption and material loss caused by friction are important problems in engineering fields. Metal-based solid self-lubricating coating, as one of the important ways to reduce material wear failure, has been widely used in aerospace, mining machinery, metallurgy and military engineering and other fields. However, with the rapid development of industrial modernization in China, the parts of mechanical equipment are often used under heavy load conditions. The traditional self-lubricating coating has low strength, low hardness and poor lubrication performance, and the external load it can withstand is generally 0.1-12 MPa, which is difficult to meet the use requirements under heavy load conditions. In the self-lubricating Cu-Sn coating system with excellent comprehensive performance, the introduction of other alloying elements by electroless plating can significantly improve the fracture toughness of the coating, enhance the crack propagation resistance of the coating, effectively prevent the local peeling of the coating during wear, and improve the wear resistance of the coating. In addition, the appropriate introduction of alloying elements can improve the strength and hardness of the coating, and also improve the oxidation resistance and heat resistance of the coating, and improve the corrosion resistance and fatigue resistance of the coating. There are many methods for preparing composite powder by introducing alloying elements, such as electroplating, mechanical mixing method, etc. However, the electroplating method has the problems of low density of the plated layer, low bonding strength and difficult operation; the mechanical mixing method has the problems of long mixing time, easy to cause powder heating, oxidation and particle size change, etc. SUMMARY

[0003] The present application provides a nickel-chromium coated tin bronze self-lubricating composite coating and a preparation method thereof to solve the problem of high wear rate of existing self-lubricating coatings under heavy load conditions. The method can obtain a self-lubricating composite coating with high fracture toughness, low wear coefficient and low wear rate, and has low raw material cost, simple process, easy control and high coating preparation efficiency.

[0004] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0005] A preparation method of a nickel-chromium coated tin bronze self-lubricating composite coating, comprising the following steps:

[0006] The electroless plated nickel tin bronze powder is placed in an electroless plated chromium solution containing a stabilizer, and is incubated at 70-90℃ for 110-130min to obtain an electroless plated composite powder with a NiCr-CuSn core-shell structure;

[0007] The electroless plated composite powder with a NiCr-CuSn core-shell structure is sprayed on the surface of the alloy substrate by a wide-speed-range high-energy plasma spraying method to form a nickel-chromium coated tin bronze self-lubricating composite coating.

[0008] Further, the stabilizer is ChCl-EG ionic liquid, including choline chloride, ethylene glycol and deionized water, the concentration of choline chloride is 70-75 g / L, and the concentration of ethylene glycol is 13.0-15.0 g / L.

[0009] Further, the chemical plating chromium solution containing the stabilizer is prepared by the following process: chromium chloride hexahydrate, sodium hypophosphite, sodium citrate, potassium thiocyanate, the stabilizer, sodium nitrite, sodium chloride, boric acid and sodium fluoride are added to deionized water, hydrochloric acid is used to adjust the pH value to 3.0-4.0, and the chemical plating chromium solution containing the stabilizer is obtained; wherein the concentration of chromium chloride hexahydrate is 70.0-80.0 g / L, the concentration of sodium hypophosphite is 13.0-13.5 g / L, the concentration of sodium citrate is 40-45 g / L, the concentration of potassium thiocyanate is 25-30 g / L, the concentration of the stabilizer is 30.0-50.0 g / L, the concentration of sodium nitrite is 0.1-1.0 g / L, the concentration of sodium chloride is 10.0-20.0 g / L, the concentration of boric acid is 20.0-30.0 g / L, and the concentration of sodium fluoride is 5.0-10 g / L.

[0010] Further, the chemical plating composite powder with the NiCr-CuSn core-shell structure has a particle size of less than 74 μm; and the thickness of the NiCr plating layer of the chemical plating composite powder with the NiCr-CuSn core-shell structure is 600-800 nm.

[0011] Further, the spraying parameters are as follows: the spraying voltage is 110-130 V, the current is 310-330 A, the argon flow rate is 170-200 L / min, the spraying distance is 90-110 mm, and the powder feeding rate is 25-35 g / min.

[0012] Further, the chemical plating nickel-tin bronze powder is prepared by the following process:

[0013] The tin bronze powder is ultrasonically treated in ethanol, then stirred in an alkaline solution, washed, and dried to obtain the degreased tin bronze powder;

[0014] The degreased tin bronze powder is roughened by nitric acid to obtain the tin bronze powder with a roughened surface;

[0015] The tin bronze powder with a roughened surface is activated by an activator to obtain the tin bronze powder with catalytic activity;

[0016] The tin bronze powder with catalytic activity is placed in a chemical plating nickel solution, stirred, washed, and dried to obtain the chemical plating nickel-tin bronze powder.

[0017] Further, the alkaline solution comprises sodium carbonate, sodium phosphate, sodium silicate, OP-10 emulsifier and deionized water, the concentration of sodium carbonate is 15.0g / L, the concentration of sodium phosphate is 15.0g / L, the concentration of sodium silicate is 35.0g / L, and the concentration of OP-10 emulsifier is 3.0g / L.

[0018] Further, the activation temperature is 155-175℃, and the time is 20-30min.

[0019] The activator comprises nickel acetate, sodium hypophosphite, ethanol and deionized water, when the ethanol is 787.0mL and the deionized water is 103.3mL, the concentration of nickel acetate is 91.8g / L, and the concentration of sodium hypophosphite is 73.0g / L.

[0020] Further, the electroless nickel plating solution is prepared by adding nickel chloride hexahydrate, sodium hypophosphite, sodium citrate and boric acid into water, and adjusting the pH value to 8-9 by using ammonia water, wherein the concentration of nickel chloride hexahydrate is 47.5g / L, the concentration of sodium hypophosphite is 12.0g / L, the concentration of sodium citrate is 40.0g / L, and the concentration of boric acid is 12.0g / L.

[0021] A nickel-chromium coated tin bronze self-lubricating composite coating prepared according to the method has a bonding strength of 67.9±3.6MPa, a friction coefficient of 0.49, and a wear rate of 0.44×10 -3 mm 3 ·N -1 ·m -1 .

[0022] Compared with the prior art, the present application has the following beneficial effects:

[0023] The application adopts a chemical plating method to prepare a chemical plating composite powder with a NiCr-CuSn core-shell structure, and the chemical plating is an important method for improving the mechanical properties of a material surface. Since the chemical plating is essentially a self-catalytic redox reaction, no external power source is needed, and the plating can be performed only by placing a material with a catalytic surface in a plating solution at a certain temperature. Compared with electroplating, the chemical plating has the advantages of economy, environmental protection, and easy operation, the deposited plating layer is more uniform and dense, and the bonding strength between the plating layer and the substrate is higher. The chemical plating composite powder prepared in the application has a particle size of about 50-130 μm, and maintains the original spherical morphology of the tin bronze powder, showing excellent fluidity. The interface between the NiCr plating layer and the tin bronze powder is well bonded, the plating layer uniformly coats the surface of the tin bronze powder, and has a thickness of about 600-800 nm and a dense layered stacking structure. After chemical plating, the original tin bronze powder surface has a NiCr plating layer, so that the melting point of the coated composite powder is increased to 1455 ℃ (the melting point of CuSn is 1083 ℃), the increase in the melting point enables the composite powder particles to fully exchange heat and mass with the plasma jet, and to impact the substrate surface at a very fast speed to form a relatively dense self-lubricating composite coating. The lap joint pores formed between the impact particles during the spraying process can capture abrasive debris, reducing abrasive wear; the filling of abrasive debris into the pores improves the mechanical strength near the pores and reduces the actual contact pressure, and the existence of the pores also affects the crack propagation mode, changes the straight-line type to the broken-line type, increases the crack propagation energy and the fracture energy of the coating.

[0024] The self-lubricating composite coating prepared in the application has a NiCr alloy phase dispersedly distributed in the structure. The Cr-rich phase is dispersed in the coating in the form of a small unit with a diameter of 1 μm, as a dispersion strengthening phase, promotes the increase of the sliding resistance of the plastic deformation of the coating, and increases the mechanical strength of the coating. In addition, the Ni and Cr introduced by chemical plating react with tin bronze during spraying to produce a new alloy phase, the formation of the alloy phase changes the regular layered arrangement of metal atoms, making the relative sliding between the atomic layers difficult, which is beneficial to improving the mechanical strength and fracture toughness of the coating. Experimental tests show that the bonding strength of the composite coating reaches 67.9±3.6 MPa, which is about 1 times higher than that of Cu-Sn, the fracture toughness is increased to 1.38 times that of the Cu-Sn coating, the friction coefficient (0.49) and the wear rate (0.44×10 -3 mm 3 ·N -1 ·m -1 ) are reduced to 0.7 times that of the Cu-Sn coating. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1It is a schematic diagram of the surface micro-morphology of the electroless plating powder of the embodiment 1 of the present application; wherein (a) is a schematic diagram of the micro-morphology, and (b) is an enlarged view of the square frame in the diagram (a);

[0026] Figure 2 It is a schematic diagram of the cross-section backscattering morphology of the electroless plating powder of the embodiment 1 of the present application; wherein (a) is a schematic diagram of the micro-morphology, and (b) is an enlarged view of the square frame in the diagram (a);

[0027] Figure 3 It is a schematic diagram of the cross-section of the self-lubricating composite coating of the embodiment 1 of the present application with different magnifications; wherein (a) is a low magnification, and (b) is a high magnification;

[0028] Figure 4 It is a schematic diagram of the wear scar 3D morphology of the self-lubricating composite coating of the embodiment 1 of the present application. DETAILED DESCRIPTION

[0029] In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to the related drawings. The preferred embodiments of the present application are shown in the drawings. However, the present application can be realized in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0030] The present application is a preparation method of a nickel-chromium coated tin bronze self-lubricating composite coating. The tin bronze powder is transferred into an alkaline solution after ultrasonic treatment in an ethanol solution and is subjected to magnetic stirring to obtain a degreased tin bronze powder. The degreased tin bronze powder is mixed with dilute nitric acid and is subjected to stirring to obtain a tin bronze powder with roughened surface. An activator is added to activate the prepared tin bronze powder. The active tin bronze powder is placed in an electroless nickel plating solution and is subjected to magnetic stirring to obtain an electroless nickel plated tin bronze powder. The electroless nickel plated tin bronze powder is placed in an electroless chromium plating solution containing a stabilizer to obtain a composite powder with a NiCr-CuSn core-shell structure. A nickel-chromium coated tin bronze self-lubricating composite coating is prepared on the surface of a substrate by a wide speed range supersonic plasma spraying method, which specifically comprises the following steps:

[0031] I. The tin bronze powder (brand CuSn10, Sn content 10wt.%) is ultrasonically treated in ethanol for 15 min, is then transferred into an alkaline solution, and is subjected to magnetic stirring at 70℃ for 20 min. The powder is washed with deionized water for 3-5 times and is dried to obtain a degreased tin bronze powder.

[0032] The alkaline solution comprises sodium carbonate, sodium phosphate, sodium silicate, OP-10 emulsifier and deionized water, and the concentrations of the components are as follows: sodium carbonate 15.0 g / L, sodium phosphate 15.0 g / L, sodium silicate 35.0 g / L, and OP-10 emulsifier 3.0 g / L.

[0033] II. The defatted tin bronze powder is mixed with 15wt.% dilute nitric acid, i.e. the dilute nitric acid is immersed in the defatted tin bronze powder, stirred for 3 minutes, washed with deionized water for 3-5 times and dried, to obtain the surface-roughened tin bronze powder.

[0034] III. The surface-roughened tin bronze powder prepared in step II is placed in an activator, i.e. the activator is immersed in the surface-roughened tin bronze powder, and kept at 155-175°C for 20-30 minutes, washed with deionized water for 3-5 times and dried;

[0035] The activator comprises nickel acetate, sodium hypophosphite, ethanol and deionized water, and the respective components are nickel acetate 91.8g / L, sodium hypophosphite 73.0g / L, ethanol 787.0mL and deionized water 103.3mL.

[0036] IV. The tin bronze powder with catalytic activity is placed in a chemical nickel plating solution, magnetically stirred at 70°C for 60 minutes, washed with deionized water for 3-5 times and dried, to obtain the chemical nickel-plated tin bronze powder;

[0037] The chemical nickel plating solution is prepared by adding nickel chloride hexahydrate, sodium hypophosphite, sodium citrate and boric acid into water, and adjusting the pH value to 8-9 with ammonia water to obtain the chemical nickel plating solution, and the respective components in the chemical nickel plating solution are nickel chloride hexahydrate 47.5g / L, sodium hypophosphite 12.0g / L, sodium citrate 40.0g / L and boric acid 12.0g / L.

[0038] V. The chemical nickel-plated tin bronze powder is placed in a chemical chromium plating solution containing a stabilizer, kept at 70-90°C for 110-130 minutes, washed with deionized water for 3-5 times and dried, and then sieved with a 200-mesh screen to obtain the chemical composite powder with NiCr-CuSn core-shell structure, wherein the particle size of the chemical composite powder with NiCr-CuSn core-shell structure should be below 74μm; the chemical composite powder with NiCr-CuSn core-shell structure comprises a NiCr plating layer wrapped on the CuSn powder, and the thickness of the NiCr plating layer is about 600-800nm.

[0039] The stabilizer is ChCl-EG ionic liquid, which comprises choline chloride, ethylene glycol and deionized water, and the concentration of choline chloride is 70-75g / L and the concentration of ethylene glycol is 13.0-15.0g / L.

[0040] The chemical plating chromium solution containing the stabilizer is prepared by the following process: adding chromium chloride hexahydrate, sodium hypophosphite, sodium citrate, potassium thiocyanate, the stabilizer, sodium nitrite, sodium chloride, boric acid and sodium fluoride into deionized water, adjusting the pH value to 3.0-4.0 by using hydrochloric acid to obtain the chemical plating chromium solution containing the stabilizer; wherein the concentration of each component of the chemical plating chromium solution is as follows: chromium chloride hexahydrate 70.0-80.0 g / L, sodium hypophosphite 13.0-13.5 g / L, sodium citrate 40-45 g / L, potassium thiocyanate 25-30 g / L, the stabilizer 30.0-50.0 g / L, sodium nitrite 0.1-1.0 g / L, sodium chloride 10.0-20.0 g / L, boric acid 20.0-30.0 g / L and sodium fluoride 5.0-10 g / L.

[0041] Six, the chemical plating composite powder with NiCr-CuSn core-shell structure is sprayed on the surface of the alloy base (1Cr17Ni2 stainless steel) by using a wide speed range high-energy plasma spraying method to form a nickel-chromium coated tin bronze self-lubricating composite coating, and the spraying parameters are as follows: the spraying voltage is 110-130 V, the current is 310-330 A, the argon flow rate is 170-200 L / min, the spraying distance is 90-110 mm, and the powder feeding rate is 25-35 g / min.

[0042] The nickel-chromium coated tin bronze self-lubricating composite coating prepared by the method has good mechanical properties, thermal conductivity, electrical conductivity, corrosion resistance and lubricating friction reduction performance. Since the copper coating has low hardness, it is limited in some harsh working conditions. Adding Sn, a soft metal material, to the copper base is an important way to improve the tribological performance of the copper-based coating material. On the one hand, Sn is mutually soluble with copper, and the mechanical properties of the copper-based coating are improved through the solid solution strengthening mechanism. On the other hand, Sn has low hardness and good ductility, and can easily slide between grains, and can still maintain good self-lubricating performance in harsh environments. The Cu-Sn coating is a typical metal-based solid self-lubricating coating. Under heavy load conditions, the wear resistance of the self-lubricating coating is closely related to its fracture toughness. High fracture toughness can make it more difficult for cracks to expand on the surface and inside of the coating, effectively reducing the local peeling of the coating caused by shear stress during friction, so that the coating exhibits a low wear rate. In order to improve the fracture toughness of the coating, Ni and Cr are introduced into the Cu-Sn coating system. The results show that the fracture toughness of the composite coating is improved to 1.38 times that of the Cu-Sn coating, the friction coefficient (0.49) and the wear rate (0.44*10 -3 mm3·N-1·m -1 ) are reduced to 0.7 times that of the Cu-Sn coating, which proves that the performance of the tin bronze self-lubricating coating is improved.

[0043] Example 1

[0044] The preparation method of the nickel-chromium coated tin bronze self-lubricating composite coating of the embodiment comprises the following steps:

[0045] I. Tin bronze powder (brand CuSn10, Sn content 10wt.%) is ultrasonically treated in ethanol for 15 min, then transferred into an alkaline solution and magnetically stirred at 70℃ for 20 min, washed with deionized water for 3-5 times and dried to obtain degreased tin bronze powder; the alkaline solution comprises sodium carbonate, sodium phosphate, sodium silicate, OP-10 emulsifier and deionized water, and the component concentrations are sodium carbonate 15.0 g / L, sodium phosphate 15.0 g / L, sodium silicate 35.0 g / L and OP-10 emulsifier 3.0 g / L.

[0046] II. The degreased tin bronze powder is mixed with 15wt.% dilute nitric acid, stirred for 3 min, washed with deionized water for 3-5 times and dried to obtain tin bronze powder with roughened surface.

[0047] III. The tin bronze powder prepared in step II is placed in an activator, heated at 165℃ for 20 min, washed with deionized water for 3-5 times and dried; the activator comprises nickel acetate, sodium hypophosphite, ethanol and deionized water, and the components are nickel acetate 91.8 g / L, sodium hypophosphite 73.0 g / L, ethanol 787.0 mL and deionized water 103.3 mL.

[0048] IV. The tin bronze powder with catalytic activity is placed in a chemical nickel plating solution, magnetically stirred at 70℃ for 60 min, washed with deionized water for 3-5 times and dried to obtain chemical nickel plated tin bronze powder; the chemical nickel plating solution is prepared by adding nickel chloride hexahydrate, sodium hypophosphite, sodium citrate and boric acid into water, and adjusting the pH value to 8-9 with ammonia water to obtain the chemical nickel plating solution; the components in the chemical nickel plating solution are nickel chloride hexahydrate 47.5 g / L, sodium hypophosphite 12.0 g / L, sodium citrate 40.0 g / L and boric acid 12.0 g / L.

[0049] V. The chemical nickel plated tin bronze powder is placed in a chemical chromium plating solution containing a stabilizer, heated at 80℃ for 120 min, washed with deionized water for 3-5 times and dried, then sieved with a 200 mesh screen to obtain chemical composite powder with NiCr-CuSn core-shell structure; the particle size of the chemical composite powder with NiCr-CuSn core-shell structure should be below 74 μm.

[0050] The stabilizer is ChCl-EG ionic liquid, which comprises choline chloride, ethylene glycol and deionized water, and the concentrations of choline chloride and ethylene glycol are 70 g / L and 13.0 g / L respectively;

[0051] The chemical plating chromium solution containing the stabilizer is prepared by the following process: adding chromium chloride hexahydrate, sodium hypophosphite, sodium citrate, potassium thiocyanate, the stabilizer, sodium nitrite, sodium chloride, boric acid and sodium fluoride into deionized water, adjusting the pH value to 3.0 by using hydrochloric acid to obtain the chemical plating chromium solution containing the stabilizer; wherein the concentration of each component of the chemical plating chromium solution is as follows: chromium chloride hexahydrate 70.0 g / L, sodium hypophosphite 13.0 g / L, sodium citrate 43.2 g / L, potassium thiocyanate 25.3 g / L, the stabilizer 40.0 g / L, sodium nitrite 0.4 g / L, sodium chloride 10.0 g / L, boric acid 23.0 g / L and sodium fluoride 6.0 g / L.

[0052] Referring to Figs. 1(a) and (b), it can be seen that the particle size of the composite powder after chemical plating is about 50-130 μm, and the original spherical morphology of the tin bronze powder is maintained. The plating layer is in a uniform micro-bump state, and presents a dense layer-like stacking structure. Figure 1 Referring to Figs. 1(a) and (b), it can be seen that the particle size of the composite powder after chemical plating is about 50-130 μm, and the original spherical morphology of the tin bronze powder is maintained. The plating layer is in a uniform micro-bump state, and presents a dense layer-like stacking structure.

[0053] Figure 2 Referring to Figs. 1(a) and (b), it can be seen that the particle size of the composite powder after chemical plating is about 50-130 μm, and the original spherical morphology of the tin bronze powder is maintained. The plating layer is in a uniform micro-bump state, and presents a dense layer-like stacking structure.

[0054] Six, the wide speed range high-energy plasma spraying process parameters are adjusted: the spraying voltage is 110 V, the current is 310 A, the argon flow rate is 170 L / min, the spraying distance is 90 mm, and the powder feeding rate is 25 g / min. The composite powder obtained by the chemical plating method, i.e., the chemical plating composite powder with the NiCr-CuSn core-shell structure, is heated to a molten or semi-molten state by the high-temperature plasma jet, and is impacted on the metal substrate (1Cr17Ni2 stainless steel) at a very high kinetic energy, so as to obtain a nickel-chromium coated tin bronze self-lubricating composite coating.

[0055] Referring to Figs. 1(a) and (b), it can be seen that the particle size of the composite powder after chemical plating is about 50-130 μm, and the original spherical morphology of the tin bronze powder is maintained. The plating layer is in a uniform micro-bump state, and presents a dense layer-like stacking structure. Figure 3 Referring to Figs. 1(a) and (b), it can be seen that the particle size of the composite powder after chemical plating is about 50-130 μm, and the original spherical morphology of the tin bronze powder is maintained. The plating layer is in a uniform micro-bump state, and presents a dense layer-like stacking structure.

[0056] Figure 4 It can be seen from Figs. 1(a) and (b) that a large number of wear debris and obvious friction films exist in the wear scar area, which indicates that the wear form of the coating is mainly adhesive wear, and is accompanied by a certain degree of abrasive cutting.

[0057] ​​The adhesion strength of the coating was determined by tensile test, and the adhesion strength of the composite coating reached 67.9±3.6MPa, which was about 1 times higher than that of Cu-Sn; the fracture toughness of the coating was obtained by indentation method, and the fracture toughness of the composite coating was increased to 1.38 times of that of Cu-Sn coating; according to the standard of ASTM G99, the pin-on-disc friction and wear test was carried out on the polished coating, and the results showed that the friction coefficient (0.49) and wear rate (0.44×10 -3 mm 3 ·N -1 ·m -1 ) of the composite coating were reduced to 0.7 times of those of Cu-Sn coating.

[0058] Example 2

[0059] The preparation method of the nickel-chromium coated tin bronze self-lubricating composite coating in the embodiment comprises the following steps:

[0060] I. Tin bronze powder (brand CuSn10, Sn content 10wt.%) was ultrasonically treated in ethanol for 15 min, then transferred into an alkaline solution and magnetically stirred at 70℃ for 20 min, washed with deionized water for 3-5 times and dried to obtain degreased tin bronze powder;

[0061] II. The degreased tin bronze powder was mixed with 15wt.% dilute nitric acid and stirred for 3 min, then washed with deionized water for 3-5 times and dried to obtain roughened tin bronze powder.

[0062] III. The tin bronze powder prepared in step II was placed in an activator and incubated at 175℃ for 25 min, then washed with deionized water for 3-5 times and dried.

[0063] IV. The tin bronze powder with catalytic activity was placed in a chemical nickel plating solution and magnetically stirred at 70℃ for 60 min, then washed with deionized water for 3-5 times and dried to obtain chemical nickel-plated tin bronze powder.

[0064] V. The chemical nickel-plated tin bronze powder was placed in a chemical chromium plating solution containing a stabilizer and incubated at 90℃ for 130 min, then washed with deionized water for 3-5 times and dried, and then sieved with a 200 mesh sieve to obtain chemical composite powder with NiCr-CuSn core-shell structure; the particle size of the chemical composite powder with NiCr-CuSn core-shell structure should be below 74μm;

[0065] The stabilizer is ChCl-EG ionic liquid, which comprises choline chloride, ethylene glycol and deionized water, and the composition is choline chloride 75g / L and ethylene glycol 14.0g / L;

[0066] The chemical plating chromium solution containing the stabilizer is prepared by the following process: adding chromium chloride hexahydrate, sodium hypophosphite, sodium citrate, potassium thiocyanate, the stabilizer, sodium nitrite, sodium chloride, boric acid and sodium fluoride into deionized water, adjusting the pH value to 3.5 by using hydrochloric acid to obtain the chemical plating chromium solution containing the stabilizer; wherein the concentration of each component of the chemical plating chromium solution is: chromium chloride hexahydrate 75.0 g / L, sodium hypophosphite 13.3 g / L, sodium citrate 44 g / L, potassium thiocyanate 26.5 g / L, the stabilizer 45.0 g / L, sodium nitrite 0.8 g / L, sodium chloride 15.0 g / L, boric acid 25.0 g / L and sodium fluoride 8.0 g / L.

[0067] Six, the wide speed range high-energy plasma spraying process parameters are adjusted: the spraying voltage is 120 V, the current is 320 A, the argon flow rate is 180 L / min, the spraying distance is 100 mm, and the powder feeding rate is 30 g / min. The composite powder obtained by the chemical plating method, i.e. the chemical plating composite powder with the NiCr-CuSn core-shell structure, is heated to a molten or semi-molten state by high-temperature plasma jet and impacts on the metal substrate (1Cr17Ni2 stainless steel) with very high kinetic energy, thereby obtaining a nickel-chromium-coated tin-bronze self-lubricating composite coating.

[0068] Example 3

[0069] The preparation method of the nickel-chromium-coated tin-bronze self-lubricating composite coating in this example comprises the following steps:

[0070] I. The tin-bronze powder (brand CuSn10, Sn content 10 wt.%) is ultrasonically treated in ethanol for 15 min, then transferred into an alkaline solution and magnetically stirred at 70℃ for 20 min. The powder is washed with deionized water for 3-5 times and dried to obtain a degreased tin-bronze powder. The alkaline solution comprises sodium carbonate, sodium phosphate, sodium silicate, OP-10 emulsifier and deionized water, and the component concentration is sodium carbonate 15.0 g / L, sodium phosphate 15.0 g / L, sodium silicate 35.0 g / L and OP-10 emulsifier 3.0 g / L.

[0071] II. The degreased tin-bronze powder is mixed with 15 wt.% dilute nitric acid and stirred for 3 min. The powder is washed with deionized water for 3-5 times and dried to obtain a surface-roughened tin-bronze powder.

[0072] III. The tin-bronze powder prepared in step II is placed in an activator and kept at 155℃ for 30 min. The powder is washed with deionized water for 5 times and dried. The activator comprises nickel acetate, sodium hypophosphite, ethanol and deionized water, and the components are nickel acetate 91.8 g / L, sodium hypophosphite 73.0 g / L, ethanol 787.0 mL and deionized water 103.3 mL.

[0073] Four, the tin bronze powder with catalytic activity is placed in the electroless nickel plating solution, is magnetically stirred for 60 min at 70℃, is washed with deionized water for 3-5 times and is dried, to obtain the electroless nickel plated tin bronze powder; the electroless nickel plating solution is prepared by the following process: nickel chloride hexahydrate, sodium hypophosphite, sodium citrate and boric acid are added to water, and the pH value is adjusted to 9 by using ammonia water, to obtain the electroless nickel plating solution, and the concentrations of the components in the electroless nickel plating solution are 47.5 g / L of nickel chloride hexahydrate, 12.0 g / L of sodium hypophosphite, 40.0 g / L of sodium citrate and 12.0 g / L of boric acid.

[0074] Five, the electroless nickel plated tin bronze powder is placed in the electroless chromium plating solution containing a stabilizer, is incubated for 130 min at 70℃, is washed with deionized water for 5 times and is dried, and then is sieved by using a 200 mesh screen, to obtain the electroless composite powder with a NiCr-CuSn core-shell structure; the particle size of the electroless composite powder with the NiCr-CuSn core-shell structure should be below 74 μm;

[0075] The stabilizer is ChCl-EG ionic liquid, which comprises choline chloride, ethylene glycol and deionized water, and the concentrations of choline chloride and ethylene glycol are 75 g / L and 14.0 g / L respectively;

[0076] The electroless chromium plating solution containing a stabilizer is prepared by the following process: chromium chloride hexahydrate, sodium hypophosphite, sodium citrate, potassium thiocyanate, a stabilizer, sodium nitrite, sodium chloride, boric acid and sodium fluoride are added to deionized water, and the pH value is adjusted to 3.0 by using hydrochloric acid, to obtain the electroless chromium plating solution containing a stabilizer; the concentrations of the components in the electroless chromium plating solution are 70.0 g / L of chromium chloride hexahydrate, 13.5 g / L of sodium hypophosphite, 40 g / L of sodium citrate, 28 g / L of potassium thiocyanate, 30.0 g / L of the stabilizer, 0.1 g / L of sodium nitrite, 20.0 g / L of sodium chloride, 25.0 g / L of boric acid and 7.0 g / L of sodium fluoride.

[0077] Six, the process parameters of the wide speed range high-energy plasma spraying are adjusted: the spraying voltage is 110 V, the current is 320 A, the argon flow rate is 170 L / min, the spraying distance is 90 mm and the powder feeding rate is 35 g / min. The composite powder obtained by the electroless plating method, i.e. the electroless composite powder with the NiCr-CuSn core-shell structure, is heated to a molten or semi-molten state by the high-temperature plasma jet, and is impacted on the metal substrate (1Cr17Ni2 stainless steel) at a very high kinetic energy, to obtain the nickel-chromium coated tin bronze self-lubricating composite coating.

[0078] Example 4

[0079] The preparation method of the nickel-chromium coated tin bronze self-lubricating composite coating in this example comprises the following steps:

[0080] I. Tin bronze powder (brand CuSn10, Sn content 10wt.%) is ultrasonically treated in ethanol for 15 min, then transferred to an alkaline solution and magnetically stirred at 70°C for 20 min. The powder is washed 3-5 times with deionized water and dried to obtain a degreased tin bronze powder. The alkaline solution comprises sodium carbonate, sodium phosphate, sodium silicate, OP-10 emulsifier and deionized water, and the component concentrations are 15.0 g / L of sodium carbonate, 15.0 g / L of sodium phosphate, 35.0 g / L of sodium silicate and 3.0 g / L of OP-10 emulsifier.

[0081] II. The degreased tin bronze powder is mixed with 15wt.% dilute nitric acid and stirred for 3 min. The powder is washed 3-5 times with deionized water and dried to obtain a tin bronze powder with roughened surface.

[0082] III. The tin bronze powder prepared in step II is placed in an activator and kept at 175°C for 20 min. The powder is washed 4 times with deionized water and dried. The activator comprises nickel acetate, sodium hypophosphite, ethanol and deionized water, and the components are 91.8 g / L of nickel acetate, 73.0 g / L of sodium hypophosphite, 787.0 mL of ethanol and 103.3 mL of deionized water.

[0083] IV. The tin bronze powder with catalytic activity is placed in a chemical nickel plating solution and magnetically stirred at 70°C for 60 min. The powder is washed 3-5 times with deionized water and dried to obtain a chemical nickel-plated tin bronze powder. The chemical nickel plating solution is prepared by adding nickel chloride hexahydrate, sodium hypophosphite, sodium citrate and boric acid to water and adjusting the pH value to 8 with ammonia water to obtain the chemical nickel plating solution. The components in the chemical nickel plating solution are 47.5 g / L of nickel chloride hexahydrate, 12.0 g / L of sodium hypophosphite, 40.0 g / L of sodium citrate and 12.0 g / L of boric acid.

[0084] V. The chemical nickel-plated tin bronze powder is placed in a chemical chromium plating solution containing a stabilizer and kept at 90°C for 110 min. The powder is washed 3-5 times with deionized water and dried, and then sieved with a 200-mesh screen to obtain a chemical composite powder with a NiCr-CuSn core-shell structure. The particle size of the chemical composite powder with the NiCr-CuSn core-shell structure should be below 74 μm.

[0085] The stabilizer is ChCl-EG ionic liquid, which comprises choline chloride, ethylene glycol and deionized water, and the concentrations of choline chloride and ethylene glycol are 72 g / L and 13.0 g / L, respectively.

[0086] The chemical plating chromium solution containing the stabilizer is prepared by the following process: adding chromium chloride hexahydrate, sodium hypophosphite, sodium citrate, potassium thiocyanate, the stabilizer, sodium nitrite, sodium chloride, boric acid and sodium fluoride into deionized water, adjusting the pH value to 4.0 by using hydrochloric acid to obtain the chemical plating chromium solution containing the stabilizer; wherein the concentration of each component of the chemical plating chromium solution is as follows: chromium chloride hexahydrate 80.0 g / L, sodium hypophosphite 13.2 g / L, sodium citrate 43 g / L, potassium thiocyanate 25 g / L, the stabilizer 40.0 g / L, sodium nitrite 0.5 g / L, sodium chloride 15.0 g / L, boric acid 20.0 g / L and sodium fluoride 10.0 g / L.

[0087] Six, the wide speed range high-energy plasma spraying process parameters are adjusted: the spraying voltage is 120 V, the current is 310 A, the argon flow rate is 200 L / min, the spraying distance is 100 mm, and the powder feeding rate is 30 g / min. The composite powder obtained by the chemical plating method, i.e., the chemical plating composite powder with the NiCr-CuSn core-shell structure, is heated to a molten or semi-molten state by high-temperature plasma jet and impacts on the metal substrate (1Cr17Ni2 stainless steel) with very high kinetic energy, thereby obtaining a nickel-chromium-coated tin-bronze self-lubricating composite coating.

[0088] Example 5

[0089] The preparation method of the nickel-chromium-coated tin-bronze self-lubricating composite coating in this embodiment comprises the following steps:

[0090] I. The tin-bronze powder (brand CuSn10, Sn content 10 wt.%) is ultrasonically treated in ethanol for 15 min, then transferred into an alkaline solution and magnetically stirred at 70℃ for 20 min, washed with deionized water for 3-5 times and dried to obtain the degreased tin-bronze powder; the alkaline solution comprises sodium carbonate, sodium phosphate, sodium silicate, OP-10 emulsifier and deionized water, and the component concentration is as follows: sodium carbonate 15.0 g / L, sodium phosphate 15.0 g / L, sodium silicate 35.0 g / L and OP-10 emulsifier 3.0 g / L.

[0091] II. The degreased tin-bronze powder is mixed with 15 wt.% dilute nitric acid, stirred for 3 min, washed with deionized water for 3-5 times and dried to obtain the tin-bronze powder with roughened surface.

[0092] III. The tin-bronze powder prepared in step II is placed in an activator, and the temperature is kept at 160℃ for 25 min, then the powder is washed with deionized water for 3 times and dried; the activator comprises nickel acetate, sodium hypophosphite, ethanol and deionized water, and the components are as follows: nickel acetate 91.8 g / L, sodium hypophosphite 73.0 g / L, ethanol 787.0 mL and deionized water 103.3 mL.

[0093] Four, the tin bronze powder with catalytic activity is placed in a chemical nickel plating solution, is stirred by a magnetic force at 70°C for 60 min, is washed with deionized water for 3-5 times and is dried, so as to obtain a chemical nickel plating tin bronze powder; the chemical nickel plating solution is prepared by the following process: nickel chloride hexahydrate, sodium hypophosphite, sodium citrate and boric acid are added into water, and the pH value is adjusted to 8.5 by using ammonia water, so as to obtain the chemical nickel plating solution, and the concentrations of the components in the chemical nickel plating solution are 47.5 g / L of nickel chloride hexahydrate, 12.0 g / L of sodium hypophosphite, 40.0 g / L of sodium citrate and 12.0 g / L of boric acid.

[0094] Five, the chemical nickel plating tin bronze powder is placed in a chemical chromium plating solution containing a stabilizer, is kept at 85°C for 120 min, is washed with deionized water for 4 times and is dried, and then is sieved by using a 200-mesh sieve, so as to obtain a chemical composite powder with a NiCr-CuSn core-shell structure; the particle size of the chemical composite powder with the NiCr-CuSn core-shell structure should be less than 74 μm.

[0095] The stabilizer is ChCl-EG ionic liquid, which comprises choline chloride, ethylene glycol and deionized water, the concentration of choline chloride is 70 g / L, and the concentration of ethylene glycol is 15.0 g / L.

[0096] The chemical chromium plating solution containing the stabilizer is prepared by the following process: chromium chloride hexahydrate, sodium hypophosphite, sodium citrate, potassium thiocyanate, the stabilizer, sodium nitrite, sodium chloride, boric acid and sodium fluoride are added into deionized water, and the pH value is adjusted to 3.0 by using hydrochloric acid, so as to obtain the chemical chromium plating solution containing the stabilizer; the concentrations of the components in the chemical chromium plating solution are 75.0 g / L of chromium chloride hexahydrate, 13.0 g / L of sodium hypophosphite, 45 g / L of sodium citrate, 30 g / L of potassium thiocyanate, 50.0 g / L of the stabilizer, 1 g / L of sodium nitrite, 10.0 g / L of sodium chloride, 30 g / L of boric acid and 5.0 g / L of sodium fluoride.

[0097] Six, the process parameters of the wide speed range high-energy plasma spraying are adjusted: the spraying voltage is 130 V, the current is 330 A, the argon flow rate is 180 L / min, the spraying distance is 110 mm, and the powder feeding rate is 25 g / min. The composite powder obtained by the chemical plating method, i.e. the chemical composite powder with the NiCr-CuSn core-shell structure, is heated to a molten or semi-molten state by a high-temperature plasma jet, and is impacted on a metal substrate (1Cr17Ni2 stainless steel) at a very high kinetic energy, so as to obtain a nickel-chromium coated tin bronze self-lubricating composite coating.

[0098] The present application obtains the chemical plating composite powder with the NiCr-CuSn core-shell structure by placing the tin bronze powder in different reagents to complete the degreasing, surface roughening, surface activation, chemical plating Ni and chemical plating Cr process flow, and adopts the wide speed range high-energy plasma spraying method to prepare the nickel-chromium coated tin bronze self-lubricating composite coating on the alloy substrate surface, and the coating structure has the NiCr alloy phase distributed in the CuSn substrate.

[0099] In the present application, the nickel-chromium alloy plating layer is deposited on the surface of the tin bronze powder, which is beneficial to improve the uniformity of the distribution of Ni and Cr in the coating, form a new alloy phase in the high-temperature spraying process, and thus improve the fracture toughness and tribological properties of the coating. The wide speed range high-energy plasma spraying method has the advantages of high temperature and high speed, and compared with the traditional plasma spraying, the coating prepared by the technology has good interface bonding between the coating and the substrate, higher density and mechanical properties, so the present application selects this technology to prepare the nickel-chromium coated tin bronze self-lubricating composite coating.

[0100] The above only describes the best embodiments of the present application, but cannot be understood as the limitation of the claims. The present application is not limited to the above embodiments, and the specific structure allows changes. Any changes made within the protection scope of the independent claims of the present application are within the protection scope of the present application.

[0101] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the application herein only for the purpose of describing specific embodiments and is not intended to limit the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

Claims

1. A method for preparing a self-lubricating composite coating of tin bronze coated with nickel-chromium, characterized in that, The method comprises the following steps: The electroless nickel-tin bronze powder is placed in the electroless chromium plating solution containing the stabilizer, and is kept at 70-90 ℃ for 110-130 min to obtain the electroless composite powder with a NiCr-CuSn core-shell structure; wherein, the electroless nickel-tin bronze powder is prepared by the following process: The tin bronze powder is ultrasonically treated in ethanol, then is stirred in an alkaline solution, is washed, and is dried to obtain the degreased tin bronze powder; The degreased tin bronze powder is roughened by nitric acid to obtain the tin bronze powder with a roughened surface; The tin bronze powder with a roughened surface is activated by an activator to obtain the tin bronze powder with catalytic activity; The tin bronze powder with catalytic activity is placed in the electroless nickel plating solution, is stirred, is washed, and is dried to obtain the electroless nickel-tin bronze powder; The tin bronze powder contains 10 wt.% of Sn; The stabilizer is ChCl-EG ionic liquid containing choline chloride, ethylene glycol, and deionized water, the concentration of choline chloride is 70-75 g / L, and the concentration of ethylene glycol is 13.0-15.0 g / L; The electroless composite powder with a NiCr-CuSn core-shell structure is sprayed on the surface of an alloy substrate by a wide-speed-range high-energy plasma spraying method to form a nickel-chromium coated tin bronze self-lubricating composite coating.

2. The method of claim 1, wherein the nickel-chromium clad tin bronze self- lubricating composite coating is prepared by the steps of: The electroless chromium plating solution containing the stabilizer is prepared by the following process: chromium chloride hexahydrate, sodium hypophosphite, sodium citrate, potassium thiocyanate, the stabilizer, sodium nitrite, sodium chloride, boric acid, and sodium fluoride are added to deionized water, hydrochloric acid is used to adjust the pH value to 3.0-4.0 to obtain the electroless chromium plating solution containing the stabilizer; wherein, the concentration of chromium chloride hexahydrate is 70.0-80.0 g / L, the concentration of sodium hypophosphite is 13.0-13.5 g / L, the concentration of sodium citrate is 40-45 g / L, the concentration of potassium thiocyanate is 25-30 g / L, the concentration of the stabilizer is 30.0-50.0 g / L, the concentration of sodium nitrite is 0.1-1.0 g / L, the concentration of sodium chloride is 10.0-20.0 g / L, the concentration of boric acid is 20.0-30.0 g / L, and the concentration of sodium fluoride is 5.0-10 g / L.

3. The method for preparing the nickel-chromium-coated tin bronze self-lubricating composite coating according to claim 1, characterized in that, The particle size of the electroless composite powder with a NiCr-CuSn core-shell structure is less than 74 μm; and the thickness of the NiCr plating layer of the electroless composite powder with a NiCr-CuSn core-shell structure is 600-800 nm.

4. The method for preparing the nickel-chromium-coated tin bronze self-lubricating composite coating according to claim 1, characterized in that, The spraying parameters are as follows: the spraying voltage is 110-130 V, the current is 310-330 A, the argon flow rate is 170-200 L / min, the spraying distance is 90-110 mm, and the powder feeding rate is 25-35 g / min.

5. The method for preparing the nickel-chromium-coated tin bronze self-lubricating composite coating according to claim 1, characterized in that, The alkaline solution contains sodium carbonate, sodium phosphate, sodium silicate, OP-10 emulsifier, and deionized water, the concentration of sodium carbonate is 15.0 g / L, the concentration of sodium phosphate is 15.0 g / L, the concentration of sodium silicate is 35.0 g / L, and the concentration of OP-10 emulsifier is 3.0 g / L.

6. The method for preparing the nickel-chromium-coated tin bronze self-lubricating composite coating according to claim 1, characterized in that, The activation temperature is 155-175 ℃, and the activation time is 20-30 min. The activator includes nickel acetate, sodium hypophosphite, ethanol and deionized water, wherein the concentration of the nickel acetate is 91.8 g / L, the concentration of the sodium hypophosphite is 73.0 g / L, the volume of the ethanol is 787.0 mL, and the volume of the deionized water is 103.3 mL.

7. The method for preparing the nickel-chromium-coated tin bronze self-lubricating composite coating according to claim 1, characterized in that, The electroless nickel plating solution is prepared by adding nickel chloride hexahydrate, sodium hypophosphite, sodium citrate and boric acid into water, and adjusting the pH value to 8-9 by using ammonia water, wherein the concentration of the nickel chloride hexahydrate is 47.5 g / L, the concentration of the sodium hypophosphite is 12.0 g / L, the concentration of the sodium citrate is 40.0 g / L, and the concentration of the boric acid is 12.0 g / L.

8. A self-lubricating composite coating of tin bronze coated with nickel-chromium prepared according to the method of any one of claims 1 to 7, characterized in that, The self-lubricating composite coating has a bonding strength of 67.9±3.6 MPa, a friction coefficient of 0.49, and a wear rate of 0.44×10 -3 mm 3 ·N -1 ·m -1 .

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