Lubricating anti-wear Fe-based coating as well as preparation method and application thereof

Abstract

The invention provides a lubricating anti-wear Fe-based coating as well as a preparation method and application thereof, and belongs to the technical field of lubricating materials. According to the method, firstly, texturing machining is conducted on the surface of an alloy substrate, mechanical U-shaped and mechanical W-shaped textured substrates are formed, the bonding strength of the iron-based coating and the alloy substrate is improved, and then the iron-based coating is prepared on the textured surfaces through the plasma inner hole spraying technology. According to the method, the substrate surface texturing treatment technology is optimized through spraying process parameters, the bonding firmness of the coating and the substrate is enhanced by means of the inner hole spraying device, and the service reliability of the iron-based alloy coating is improved. Furthermore, a solid lubricant is introduced by utilizing the layered structure and easy-to-shear characteristic of molybdenum disulfide, and MoS2 powder and Fe alloy powder are compounded, so that on the premise of not influencing the bonding firmness of the coating, the lubricating wear resistance of the coating is improved, and the tribological adaptability of the iron-based coating is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of lubricating materials, and particularly relates to a lubricating and anti-wear Fe-based coating, a preparation method thereof and an application thereof. Background Art

[0002] At present, improving the thermal efficiency of internal combustion engines and their service reliability is an important technical approach for energy conservation and emission reduction in the internal combustion engine industry. Reducing the friction work of the engine and reducing the heat loss in the cylinder are one of the key technologies for improving the thermal efficiency of the engine. The technology of plasma spraying low-carbon iron-based alloy coatings on the inner wall of cylinders is to coat the inner surface of the aluminum alloy internal combustion engine cylinder liner with low-carbon alloy powder materials by using the atmospheric plasma spraying process, so as to achieve the performance of low friction and high wear resistance, and realize the use goals of improving the thermal efficiency and reducing fuel consumption. This technology effectively integrates the advantages of reducing the internal mechanical loss and heat loss of the internal combustion engine assembly and reducing the engine weight, and breaks through the traditional cylinder liner design.

[0003] However, aluminum alloy has low hardness, poor high-temperature resistance and high-temperature wear resistance, and is prone to scratching during actual service, resulting in scratches on the inner wall, which in turn affects the quality of the whole part and brings potential hazards. The defects of the domestic technology of plasma spraying low-carbon iron-based alloy coatings on the inner wall of cylinders are mainly reflected in two aspects: ① The bonding strength between the plasma spraying coating and the substrate is low, which cannot meet the long-life use requirements of internal combustion engines; ② The tribological adaptability of the coating is poor. During operation, the cylinder is subjected to friction and corrosion, resulting in serious abrasive wear, adhesive wear and corrosive wear, which affects the operation stability and reliability of the internal combustion engine. Summary of the Invention

[0004] The purpose of the present invention is to provide a lubricating and anti-wear Fe-based coating, a preparation method thereof and an application thereof, which can improve the bonding strength between the coating and the substrate and improve the tribological adaptability of the coating.

[0005] In order to achieve the above invention purpose, the present invention provides the following technical solutions:

[0006] The present invention provides a preparation method of a lubricating and anti-wear Fe-based coating, comprising the following steps:

[0007] Performing surface texturing treatment on an alloy substrate to obtain an alloy substrate with a textured surface;

[0008] Adopting the plasma internal hole spraying method to spray a binder onto the textured surface to form a bonding layer on the textured surface of the alloy substrate, and then spraying iron-based powder materials onto the bonding layer to form an iron-based coating, thereby obtaining a lubricating and anti-wear Fe-based coating;

[0009] The textured surface is a mechanical U-shaped texture or a mechanical W-shaped texture;

[0010] The iron-based powder material is an Fe alloy powder or a MoS 2 -Fe alloy powder.

[0011] Preferably, the alloy substrate includes aluminum alloy for lightweight internal combustion engine cylinders.

[0012] Preferably, the aluminum alloy for lightweight internal combustion engine cylinders includes Al-Si series aluminum alloy, Al-Cu series aluminum alloy or Al-Si-Cu series aluminum alloy.

[0013] Preferably, the Fe alloy powder includes Fe316L, Fe316, Fe304 or Fe304L.

[0014] Preferably, the MoS 2 -Fe alloy powder includes 10-18 wt% MoS 2 and 82-90 wt% Fe alloy powder.

[0015] Preferably, the spraying conditions of the iron-based coating include: current 500-600 A, voltage 50-70 V, spraying distance 80-150 mm, spray gun moving speed 10 mm / s, turntable rotation speed 150 rpm, powder feeding rate 20-30 g / min.

[0016] Preferably, the binder is NiCrAlY powder; the spraying conditions of the bonding layer include: current 600-700 A, voltage 55-70 V, spraying distance 100-150 mm, spray gun moving speed 10 mm / s, turntable rotation speed 150 rpm, powder feeding rate 30±5 g / min.

[0017] Preferably, the mechanical U-shaped texture or mechanical W-shaped texture is processed by a numerical control machine tool, and the linear moving speed of the numerical control machine tool processing is 5-8 μm / s.

[0018] The present invention provides a lubricating and anti-wear Fe-based coating prepared by the preparation method described in the above technical solution.

[0019] The present invention provides an application of the lubricating and anti-wear Fe-based coating described in the above technical solution in a lightweight internal combustion engine cylinder.

[0020] The present invention provides a lubricating and anti-wear Fe-based coating. First, the surface of the alloy substrate is textured to form a mechanical "U"-shaped and mechanical "W"-shaped textured substrate, improving the bonding strength between the iron-based coating and the alloy substrate. Then, a plasma internal hole spraying technique is used to prepare the iron-based coating on the textured surface. Starting from the tribology of internal combustion engine power components, the present invention optimizes the substrate surface texturing treatment technology through spraying process parameters, and with the help of an internal hole spraying device, enhances the bonding firmness between the coating and the substrate, and improves the service reliability of the iron-based alloy coating. Further, the present invention introduces a solid lubricant by utilizing the layered structure and easy shear characteristics of molybdenum disulfide, and compounding MoS 2 powder with Fe alloy powder, which improves the lubrication and wear resistance of the coating and the tribological adaptability of the iron-based coating without affecting the bonding firmness of the coating.

[0021] The method of the present invention can prepare an Fe-316L coating on the inner wall of an aluminum alloy cylinder liner, significantly improving the mechanical and anti-wear properties of the cylinder liner, and becoming an ideal solution for the coordinated optimization of light weight and high performance. In terms of mechanical properties, the hardness of the Fe-316L coating (150 - 250 HV) is much higher than that of the aluminum alloy substrate (60 - 100 HB), which can effectively resist plastic deformation and surface scratches under high pressure and high load conditions. Through the plasma spraying process, the bonding strength between the coating and the aluminum substrate is relatively high, and combined with the high toughness of the 316L austenitic structure, the problem of brittle peeling of the coating is avoided. At the same time, the high-temperature stability of 316L below 600 °C is significantly better than that of the aluminum alloy, which can reduce the risk of coating softening or creep caused by the high temperature of the engine. In addition, the present invention further incorporates molybdenum disulfide (MoS 2 ) into the Fe-316L coating, which can significantly improve the anti-friction performance: the layered structure of MoS 2 forms a solid lubricating film through the slip of the (002) crystal plane, reducing the friction coefficient; its nanoparticles can also fill the surface defects of the coating, blocking the direct contact of metals to reduce adhesive wear. In addition, the Fe-316L matrix bears the main load, while MoS 2 acts as a soft phase to absorb stress oscillations, and the two cooperate to enhance the anti-abrasive wear ability. Description of the Drawings

[0022] Figure 1 For the morphology and composition of the Al 2 O 3 sandblasting grits in Comparative Example 1, where (a) is the scanning electron microscope morphology of the grits, (b) is the O element distribution of the grits, and (c) is the Al element distribution of the grits;

[0023] Figure 2 For the surface, cross-section and three-dimensional morphology of the sandblasted texture in Comparative Example 1, where (a) is the photo of the sandblasted texture; (b) is the scanning electron microscope morphology of the sandblasted texture surface; (c) is the scanning electron microscope morphology of the cross-section of the sandblasted texture; (d) is the three-dimensional morphology and roughness of the sandblasted texture;

[0024] Figure 3 For the laser-textured surface, cross-section and three-dimensional morphology in Comparative Example 2, where (a) is a photo of the laser texture; (b) is the scanning electron microscopy (SEM) morphology of the laser-textured surface; (c) is the SEM morphology of the cross-section of the laser texture; (d) is the three-dimensional morphology and roughness of the laser texture;

[0025] Figure 4 For the mechanical "U"-shaped textured surface, cross-section and three-dimensional morphology in Example 1, where (a) is a photo of the "U"-shaped texture; (b) is the SEM morphology of the "U"-textured surface; (c) is the SEM morphology of the cross-section of the "U" texture; (d) is the three-dimensional morphology and roughness of the "U" texture;

[0026] Figure 5 For the mechanical "W"-shaped textured surface, cross-section and three-dimensional morphology in Example 2, where (a) is a photo of the "W"-shaped texture; (b) is the SEM morphology of the "W"-textured surface; (c) is the SEM morphology of the cross-section of the "W" texture; (d) is the three-dimensional morphology and roughness of the "W" texture;

[0027] Figure 6 For the cross-section photos of the Fe-based coatings after tensile testing in Examples 1-2 and Comparative Examples 1-2, where (a) is the sandblasted texture; (b) is the laser texture; (c) is the "U"-shaped texture; (d) is the "W"-shaped texture;

[0028] Figure 7 For the light microscopy morphologies of the cross-sections of the Fe-based coatings after tensile testing in Examples 1-2 and Comparative Examples 1-2, where (a) is the sandblasted texture; (b) is the laser texture; (c) is the "U"-shaped texture; (d) is the "W"-shaped texture;

[0029] Figure 8 For the bonding strengths of the Fe-based coatings with different textures in Examples 1-2 and Comparative Examples 1-2;

[0030] Figure 9 For the friction coefficients of the "W"-shaped textured Fe coating in Example 2 and the Fe-15MoS 2 coating in Example 3. Detailed implementation manners

[0031] In the present invention, unless otherwise specified, the raw materials or reagents required for preparation are all commercially available products well-known to those skilled in the art.

[0032] The present invention provides a method for preparing a lubricating and anti-wear Fe-based coating, comprising the following steps:

[0033] Subject the alloy substrate to surface texturing treatment to obtain an alloy substrate with a textured surface;

[0034] Adopt the plasma internal hole spraying method to spray the binder onto the textured surface, form a bonding layer on the textured surface of the alloy substrate, then spray the iron-based powder onto the bonding layer to form an iron-based coating, and obtain a lubricating and anti-wear Fe-based coating;

[0035] The textured surface is a mechanical U-shaped texture or a mechanical W-shaped texture;

[0036] The iron-based powder is Fe alloy powder or MoS 2 -Fe alloy powder.

[0037] In the present invention, the alloy substrate is subjected to surface texturing treatment to obtain an alloy substrate with a textured surface.

[0038] In the present invention, the alloy substrate preferably includes aluminum alloy for lightweight internal combustion engine cylinders, but is not limited to aluminum alloy.

[0039] In the present invention, the aluminum alloy for lightweight internal combustion engine cylinders preferably includes Al-Si series aluminum alloy, Al-Cu series aluminum alloy or Al-Si-Cu series aluminum alloy.

[0040] In the present invention, the Al-Si series aluminum alloy is preferably A390; the Al-Cu series aluminum alloy is preferably 201 or 202; the Al-Si-Cu series aluminum alloy is preferably A319 or A356.

[0041] In the present invention, the alloy substrate is preferably cut into cylindrical specimens with dimensions of Φ25.4mm×50mm. The surface of the specimens is mechanically polished before texturing. 800-mesh diamond sandpaper is selected for polishing until the surface roughness Ra = 0.05±0.01μm. The surface is ultrasonically cleaned with acetone to remove surface contaminants.

[0042] In the present invention, the mechanical U-shaped texture or mechanical W-shaped texture is processed by a numerically controlled machine tool. The linear movement speed of the numerically controlled machine tool processing is preferably 5-8μm / s; the mechanical U-shaped texture or mechanical W-shaped texture is preferably processed with a diamond wire with a diameter of 10μm.

[0043] After the surface texturing treatment is completed, the present invention preferably ultrasonically cleans the obtained material with acetone to wash away the residual grit, oil stain and grease contaminants during the processing, and ensure the cleanliness of the substrate surface.

[0044] After obtaining the alloy substrate with a textured surface, the present invention adopts the plasma internal hole spraying method to spray the binder onto the textured surface, form a bonding layer on the textured surface of the alloy substrate, then spray the iron-based powder onto the bonding layer to form an iron-based coating, and obtain a lubricating and anti-wear Fe-based coating.

[0045] In the present invention, the iron-based powder is Fe alloy powder or MoS 2-Fe alloy powder.

[0046] In the present invention, the Fe alloy powder preferably includes Fe316L, Fe316, Fe304 or Fe304L.

[0047] In the present invention, the MoS 2 -Fe alloy powder preferably includes 10-18 wt% MoS 2 and 82-90 wt% Fe alloy powder, more preferably 15 wt% MoS 2 and 85 wt% Fe alloy powder.

[0048] In the present invention, an M10 three-dimensional mixer (Grinder, Beijing Gediman Instrument Equipment Co., Ltd.) is preferably used to mix the MoS 2 and the Fe alloy powder evenly to obtain the MoS 2 -Fe alloy powder.

[0049] Before spraying, the present invention preferably preheats the surface of the textured substrate to 120 ± 5 °C to prevent the formation of a large amount of amorphous phase due to too fast cooling rate.

[0050] In the present invention, an 11MB atmospheric plasma internal hole spraying system (APS, Sulzer Metco9MC, SulzerMetco (US) Inc., USA) is preferably used to spray iron-based powder on the textured surface to prepare an iron-based coating: First, NiCrAlY powder is sprayed on the substrate surface as a bonding layer, and then the iron-based powder is sprayed on the surface of the bonding layer to form a composite coating.

[0051] In the present invention, the spraying conditions of the bonding layer are preferably: current 600-700 A, voltage 55-70 V, spraying distance 100-150 mm, gun moving speed 10 mm / s, turntable rotation speed 150 rpm, powder feeding rate 30 ± 5 g / min; more preferably current 650 A, voltage 60 V, spraying distance 150 mm. The functions of the bonding layer in the present invention are: (1) matching the thermal expansion coefficients of the Fe-based coating and the substrate to reduce the interfacial stress; (2) enhancing the adhesion between the coating and the substrate through micro-metallurgical bonding; (3) resisting high-temperature oxidation and corrosion, and using Al, Cr to generate a dense oxide film (Al 2 O 3 , Cr 2 O 3 ) to block the corrosive medium.

[0052] In the present invention, the spraying thickness of the bonding layer is preferably 150-200 μm, more preferably 150-180 μm.

[0053] In the present invention, the spraying conditions of the iron-based coating preferably include: current 500 - 600 A, voltage 50 - 70 V, spraying distance 80 - 150 mm, gun moving speed 10 mm / s, turntable rotation speed 150 rpm, powder feeding rate 20 - 30 g / min. The current is more preferably 550 A or 600 A, the voltage is more preferably 50 V or 65 V, and the spraying distance is more preferably 100 - 150 mm.

[0054] The present invention has no special limitation on the specific structural parameters of the textured surface being a mechanical U-shaped texture or a mechanical W-shaped texture, which can be adjusted according to actual needs. As a preferred embodiment of the present invention, the depth of the mechanical "U"-shaped texture coating is preferably 80 - 120 μm, more preferably 100 μm, the width is preferably 80 - 120 μm, more preferably 100 μm, and the groove pitch is preferably 180 - 220 μm, more preferably 200 μm. The depth of the mechanical "W"-shaped texture coating is preferably 80 - 120 μm, more preferably 100 μm, the width is preferably 180 - 220 μm, more preferably 200 μm, and the groove pitch is preferably 50 - 60 μm, more preferably 50 μm.

[0055] In the present invention, the thickness of the iron-based coating is preferably 300 - 350 μm, more preferably 320 μm.

[0056] The present invention provides a lubricating and anti-wear Fe-based coating prepared by the preparation method described in the above technical solution.

[0057] The present invention provides the application of the above-mentioned lubricating and anti-wear Fe-based coating in a lightweight internal combustion engine cylinder. The present invention has no special limitation on the application method, and it can be applied according to the methods well-known in the art.

[0058] The following is a detailed description of the specific embodiments of the present invention, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the protection scope of the present invention. In the embodiments of the present invention, the experimental methods, unless otherwise specified, are all conventional methods.

[0059] The following experimental methods and detection methods, unless otherwise specified, are all conventional methods; the following reagents and raw materials, unless otherwise specified, are all commercially available.

[0060] In the following examples, the aluminum alloy substrate used is A390 of the Al-Si series, with the composition: Si 12 - 18%, Cu 4 - 5%, Mg 0.5 - 0.7%, Fe ≤ 0.8%, purchased from Hebei Xinlizhong Nonferrous Metal Group Co., Ltd.

[0061] The Fe316L powder was purchased from Beijing General Research Institute of Mining and Metallurgy New Materials Technology Co., Ltd. The main components are C content ≤ 0.03%, Cr 16 - 18%, Ni 10 - 14%, Mo 2 - 3%, Mn ≤ 2.0%, Si ≤ 1.0%, P ≤ 0.045%, S ≤ 0.030%.

[0062] MoS 2 The powder was purchased from Beijing General Research Institute of Mining and Metallurgy New Materials Technology Co., Ltd.

[0063] The NiCrAlY powder was sourced from Oerlikon Metco (USA) Corporation.

[0064] Table 1 Spraying Process Parameters of Iron - based Coatings

[0065]

[0066] In Table 1, Fe corresponds to the Fe - based coating prepared from Fe316L powder, and Fe - 15MoS 2 corresponds to the Fe - based coating prepared from MoS 2 -Fe alloy powder.

[0067] Example 1

[0068] The aluminum alloy substrate A390 was cut into cylindrical specimens with dimensions of Φ25.4mm × 50mm. It was polished with 800 - mesh diamond sandpaper until the surface roughness Ra = 0.05 ± 0.01μm. After ultrasonic cleaning the surface with acetone, a diamond wire with a diameter of 10μm was used on a numerically controlled machine tool to process the cylindrical specimens. The wire moving speed was 8μm / s, forming a mechanical "U" - shaped texture coating with a depth of 100μm, a width of 100μm, and a groove pitch of 200μm.

[0069] Before spraying, the substrate surface was pre - heated to 120 ± 5°C. On the mechanical "U" - shaped texture surface, an Fe coating was prepared according to the spraying parameters in Table 1. An 11MB atmospheric plasma internal hole spraying system was used for coating. First, NiCrAlY powder was sprayed as the bonding layer with a thickness of 150μm, and then Fe316L powder was sprayed as the top layer to obtain an Fe - based coating with a thickness of 320μm.

[0070] Example 2

[0071] The difference from Example 1 is only that: a diamond wire with a diameter of 10μm was used on a numerically controlled machine tool to process the cylindrical specimens, forming a mechanical "W" - shaped texture coating with a depth of 100μm, a width of 200μm, and a groove pitch of 50μm. Then, on the mechanical "W" - shaped texture surface, NiCrAlY powder was first sprayed as the bonding layer according to the spraying parameters in Table 1, and then Fe316L powder was sprayed as the top layer. Other parameters were the same as those in Example 1 to obtain an Fe coating.

[0072] Example 3

[0073] The difference from Example 2 is only that: on the surface of the mechanical "W" texture, NiCrAlY powder is first sprayed as a bonding layer according to the spraying parameters in Table 1, and then MoS 2 -Fe alloy powder (15 wt% MoS 2 and 85 wt% Fe alloy powder) is used as the top layer, and other parameters are the same as those in Example 2 to obtain an Fe coating.

[0074] Comparative Example 1

[0075] The aluminum alloy substrate A390 was cut into cylindrical specimens with dimensions of Φ25.4 mm × 50 mm, polished with 800-mesh diamond sandpaper to a surface roughness Ra = 0.05 ± 0.01 μm. After ultrasonic cleaning the surface with acetone, irregular polygonal Al 2 O 3 grit with a particle size of 46 meshes was sprayed on the cylindrical specimens of Φ25.4 mm × 50 mm. The sandblasting process parameters were: sandblasting pressure 0.6 MPa, spraying distance 100 mm, sandblasting direction 90°, and time 120 s to obtain a sandblasted texture coating;

[0076] The surface of the sandblasted texture substrate was preheated to 120 ± 5 °C. According to the spraying parameters in Table 1, on the sandblasted texture surface, an 11MB atmospheric plasma internal hole spraying system was used to first spray NiCrAlY powder as a bonding layer, and then Fe316L powder as the top layer. Other conditions were the same as those in Example 1 to obtain an Fe coating.

[0077] Comparative Example 2

[0078] The aluminum alloy substrate A390 was cut into cylindrical specimens with dimensions of Φ25.4 mm × 50 mm, polished with 800-mesh diamond sandpaper to a surface roughness Ra = 0.05 ± 0.01 μm. After ultrasonic cleaning the surface with acetone, a laser microprocessing processor (Bright Solution, Italy; wavelength 1.06 μm, power 3 W, and frequency 10 kHz) was used to process the surface of the cylindrical specimens to form a laser texture coating;

[0079] Before spraying, the surface of the substrate was preheated to 120 ± 5 °C. According to the spraying parameters in Table 1, an Fe coating was prepared on the laser texture surface. An 11MB atmospheric plasma internal hole spraying system was used for coating. First, NiCrAlY powder was sprayed as a bonding layer, and then Fe316L powder was sprayed as the top layer. Other conditions were the same as those in Example 1 to obtain an Fe-based coating.

[0080] Characterization and performance testing

[0081] 1) Figure 1 For Al in Comparative Example 12 O 3 Morphology and composition of sandblasting grit, where (a) is the SEM morphology of the grit; (b) is the O element distribution of the grit; (c) is the Al element distribution of the grit; as Figure 1 can be seen, the texture presents an irregular triangular pyramid structure.

[0082] 2) Figure 2 Surface, cross-section and three-dimensional morphology of the sandblasted texture in Comparative Example 1, where (a) is a photo of the sandblasted texture; (b) is the SEM morphology of the sandblasted texture surface; (c) is the SEM morphology of the sandblasted texture cross-section; (d) is the three-dimensional morphology and roughness of the sandblasted texture; as Figure 2 shown, the overall surface after sandblasting is still flat ( Figure 2 (a) in), but from the local enlarged view, randomly distributed pits and protrusions with different shapes can be observed, without a fixed orientation ( Figure 2 (b) and (c) in). The surface roughness Ra increases from 0.05 μm after polishing to 3.3 μm ( Figure 2 (d) in), which increases the contact area between the coating and the substrate and is beneficial to improving the interfacial bonding between the two.

[0083] 3) Figure 3 Surface, cross-section and three-dimensional morphology of the laser texture in Comparative Example 2, where (a) is a photo of the laser texture; (b) is the SEM morphology of the laser texture surface; (c) is the SEM morphology of the laser texture cross-section; (d) is the three-dimensional morphology and roughness of the laser texture; as Figure 3 shown, the laser texture is generally composed of many parallel "U"-shaped grooves, the groove width and depth are both 100 μm, the spacing is 200 μm, and the surface roughness is 41.7 μm. Sufficient energy during the laser processing causes melting, gasification / sublimation and decomposition on the surface of the aluminum alloy substrate. At the same time, the Gibbs free energy of aluminum to form oxides is extremely low, and the diffusion rate of aluminum atoms is fast, so it is extremely easy to be oxidized. Figure 3 (b) in shows that many protrusions appear in the grooves, and there are obvious bulges at the groove intervals, which are obviously the result of oxide accumulation.

[0084] 4) Figure 4 Surface, cross-section and three-dimensional morphology of the mechanical "U"-type texture in Example 1, where (a) is a photo of the "U"-type texture; (b) is the SEM morphology of the "U"-type texture surface; (c) is the SEM morphology of the "U"-type texture cross-section; (d) is the three-dimensional morphology and roughness of the "U"-type sandblasted texture; as Figure 4 shown, the mechanical "U"-type texture is generally composed of many parallel "U"-shaped grooves, the groove width and depth are both 100 μm, the spacing is 200 μm, and the surface roughness Ra is 104.6 μm. The area near the groove is smooth and flat, and no obvious loose bulges are found, indicating that there is no oxidation on the surface during the processing.

[0085] 5) Figure 5 For the mechanical "W"-type texture surface, cross-section and three-dimensional morphology in Example 2, where (a) is a photo of the "W"-type texture; (b) is the scanning electron microscope morphology of the "W"-type texture surface; (c) is the scanning electron microscope morphology of the cross-section of the "W"-type texture; (d) is the three-dimensional morphology and roughness of the "W"-type texture; as Figure 5 shown, the mechanical "W"-type texture is generally composed of many parallel "W"-shaped grooves. The groove width is 200 μm, the depth is 100 μm, the spacing is 50 μm, and the surface roughness Ra is 47.6 μm. The area near the groove is smooth, and no obvious loose bulges are found, indicating that there is no oxidation on the surface during the processing.

[0086] 6) According to ASTM C633 standard, the tensile method was used to measure the coating bonding strength. Commercial E-7 epoxy resin glue (Shanghai Synthetic Resin Research Institute, China) was selected to bond two cylindrical specimens, one of which was a coated sample and the other was a sandblasted sample. After bonding, it was left stationary at room temperature for 1 h, and then placed in an oven for heat curing at 100 °C for 3 h. A universal material testing machine controlled by a microcomputer (WDW-200, S&D Instrument Manufacturing Co., Ltd., China) was used for the bonding strength test, and the tensile rate was 0.5 mm / min. To reduce errors, five groups of specimens were made, that is, each test was repeated 5 times, and the average value was the coating bonding strength obtained by this texture process.

[0087] Figure 6 For the cross-section photos of the Fe-based coatings after tensile testing in Examples 1-2 and Comparative Examples 1-2, where (a) is the sandblasted texture; (b) is the laser texture; (c) is the "U"-type texture; (d) is the "W"-type texture; Figure 7 For the optical microscope morphologies of the cross-sections of the Fe-based coatings after tensile testing in Examples 1-2 and Comparative Examples 1-2, where (a) is the sandblasted texture; (b) is the laser texture; (c) is the "U"-type texture; (d) is the "W"-type texture; Figure 8 For the bonding strengths of different textured Fe-based coatings in Examples 1-2 and Comparative Examples 1-2.

[0088] It can be Figures 6 - 8 seen that the bonding strengths of the five groups of specimens in Comparative Example 1 are 32.3, 33.7, 31.9, 34.1 and 32.3 MPa respectively, and the average value is 32.9 MPa ( Figure 8 ). The tensile cross-section photos and optical microscope morphologies show that the coating peeled off completely from the substrate position ( Figure 6 (a) in Figure 7 and

[0089] The bonding strengths of the five groups of specimens in Comparative Example 2 were 30.1, 29.4, 30.7, 31.1, and 30.3 MPa, respectively, with an average value of 30.1 MPa( Figure 8 ). Oxidation of the laser-textured surface reduced the interfacial bonding between the coating and the substrate. As shown by the tensile fracture photos and optical microscopy morphology, the coating peeled off completely from the substrate position, and the bonding strength was lower than that of the sandblasted-textured coating( Figure 6 (b) in Figure 7 and (b) in

[0090] ). The bonding strengths of the five groups of specimens in Example 1 were 36.4, 35.6, 37.1, 35.9, and 36.9 MPa, respectively, with an average value of 36.4 MPa( Figure 8 ). As shown by the tensile fracture photos and optical microscopy morphology, part of the coating peeled off from the substrate position, and the bonding strength was higher than that of the sandblasted-textured and laser-textured coatings( Figure 6 (c) in Figure 7 and (c) in

[0091] ). The bonding strengths of the five groups of specimens in Example 2 were 42.3, 41.6, 42.1, 45.9, and 41.9 MPa, respectively, with an average value of 42.76 MPa( Figure 8 ). As shown by the tensile fracture photos and optical microscopy morphology, the fracture occurred inside the coating, and there was an obvious mechanical interlock between the coating and the substrate. The bonding strength was higher than that of the sandblasted-textured, laser-textured, and mechanically "U"-shaped textured coatings( Figure 6 (d) in Figure 7 and (d) in

[0092] ). 7) Tribological property test

[0093] The friction tests of the "W"-shaped textured Fe coating in Example 2 and the "W"-shaped textured Fe-15MoS 2 coating in Example 3 were carried out at room temperature in an atmospheric environment using a UMT-3 friction testing machine (Bruker Corp., USA) to obtain the friction coefficient curves and values. Before the test, the coating was polished to make the surface roughness less than 0.1 μm. An Al 2 O 3 ball (diameter 10 mm) was selected as the counter material, with a load of 10 N, a sliding speed of 0.1 m / s, and a duration of 30 min. Then, a MicroXAM-800 three-dimensional profiler (KLA-tensor Corp., USA) was used to measure the wear volume (V, mm 3 ) of the coating. Then, the wear rate (W, mm 3 N -1 m -1 ) of the coating was calculated according to the formula W = / SP(1), where S and P represent the total sliding distance (m) and the load (N), respectively. The results are shown in Figure 9and Table 2.

[0094] As Figure 9 shown in and Table 2, the average friction coefficient of the "W"-type textured Fe coating within 30 min is 0.49 ( Figure 9 ); then the wear volume of the coating was measured using a MicroXAM-800 three-dimensional profiler, and the wear rate of the coating was obtained as 10.2×10 -5 mm 3 N -1 m -1 (Table 2).

[0095] As Figure 9 shown in and Table 2, the Fe-15MoS 2 coating has an average friction coefficient of 0.22 within 30 min ( Figure 9 ). Then the wear volume of the coating was measured using a MicroXAM-800 three-dimensional profiler, and the wear volume of the coating was obtained as 5.3×10 -5 mm 3 N -1 m -1 (Table 2).

[0096] Table 2 Friction coefficients and wear rates of the "W"-type textured Fe coating and Fe-15MoS 2 coating

[0097]

[0098] Therefore, the mechanical "W"-type textured Fe-15MoS 2 coating has the highest bonding strength and anti-friction and anti-wear properties.

[0099] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing a lubricating and anti-wear Fe-based coating, characterized in that: The following steps are involved: The alloy substrate is subjected to surface texturing treatment to obtain an alloy substrate having a textured surface; A plasma inner hole spraying method is adopted to spray a binder onto the texture surface to form a bonding layer on the texture surface of the alloy substrate, and then an iron-based powder is sprayed onto the bonding layer to form an iron-based coating to obtain a lubricating and anti-wear Fe-based coating; The textured surface is a mechanical U-shaped texture or a mechanical W-shaped texture; The iron-based powder is Fe alloy powder or MoS2-Fe alloy powder.

2. The preparation method according to claim 1, characterized in that: The alloy substrate includes a lightweight aluminum alloy for internal combustion engine cylinders.

3. The preparation method according to claim 2, characterized in that: The aluminum alloy for lightweight internal combustion engine cylinders includes Al-Si aluminum alloy, Al-Cu aluminum alloy or Al-Si-Cu aluminum alloy.

4. The preparation method according to claim 1, characterized in that: The Fe alloy powder includes Fe316L, Fe316, Fe304 or Fe304L.

5. The preparation method according to claim 4, characterized in that: The MoS2-Fe alloy powder comprises 10-18wt% MoS2 and 82-90wt% Fe alloy powder.

6. The preparation method according to claim 1, characterized in that: The spraying conditions of the iron-based coating include: current 500-600A, voltage 50-70V, spraying distance 80-150mm, spray gun moving speed 10mm / s, turntable speed 150rpm, powder feeding rate 20-30g / min.

7. The preparation method according to claim 1, characterized in that: The bonding material is NiCrAlY powder; the spraying conditions of the bonding layer include: current 600-700A, voltage 55-70V, spraying distance 100-150mm, spray gun moving speed 10mm / s, turntable speed 150rpm, and powder feeding rate 30±5g / min.

8. The preparation method according to claim 1, characterized in that: The mechanical U-shaped texture or mechanical W-shaped texture is processed by a numerically controlled machine tool, and the linear moving speed of the numerically controlled machine tool processing is 5 to 8 μm / s.

9. The lubricating and anti-wear Fe-based coating prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the lubricating and anti-wear Fe-based coating according to claim 9 in a cylinder of a lightweight internal combustion engine.

Images