Piston rod with self-lubricating coating and preparation method thereof

Abstract

The invention provides a piston rod with a self-lubricating coating and a preparation method of the piston rod. The piston rod comprises a substrate and a chromic oxide layer which are arranged in a stacked mode. The chromic oxide layer comprises a chromic oxide inner layer and a chromic oxide film layer which are arranged in a stacked mode, the chromic oxide inner layer is located in the direction close to the substrate, and the density of the chromic oxide film layer is higher than that of the chromic oxide inner layer; the surface of the chromium oxide layer is provided with at least one pit, and each pit is filled with lubricating filler. According to the piston rod with the self-lubricating coating, the compact chromium oxide film layer has high corrosion resistance and abrasion resistance and can effectively block and isolate grease with corrosion property from immersing, and therefore it is guaranteed that the bonding strength of the chromium oxide layer and a substrate is not affected by corrosion factors; in addition, at least one pit is formed in the surface of the chromium oxide layer, the lubricating filler can be filled in the pit, a good lubricating effect is achieved, and therefore the lubricating performance of the piston rod is further improved.

Description

Technical Field

[0001] The invention belongs to the technical field of surface modification, and relates to a piston rod with a self-lubricating coating, and in particular to a piston rod with a self-lubricating coating and a preparation method thereof. Background Art

[0002] Chromium oxide coating has excellent properties such as high hardness, wear resistance, corrosion resistance and low friction coefficient. It has very stable chemical properties, is insoluble in acids, alkalis, salts and various organic solvents, has excellent resistance to medium immersion corrosion and gas corrosion, and has excellent grinding performance. It is widely used in aerospace, petrochemical, mechanical metallurgy, electronic energy and catalysis.

[0003] For piston rod workpieces containing chromium oxide coatings, it is relatively common to use plasma spraying to prepare chromium oxide coatings. However, plasma spraying uses plasma arc as a heat source, and the spraying material is a high-melting-point chromium oxide ceramic. Therefore, when plasma spraying is used to prepare chromium oxide coatings, the bonding strength and density of the obtained chromium oxide coatings are limited, and it is difficult for the chromium oxide coatings to fully exert their wear resistance and corrosion resistance protective properties.

[0004] In addition, although the chromium oxide coating has a high porosity, under the action of coating friction and wear conditions, the higher porosity is beneficial to a certain extent to maintain sufficient lubricating fluid on the contact surface and reduce harmful conditions such as dry friction and sliding wear. However, due to the impregnation of liquids such as grease, and the lubricating fluids in the working environment are mostly corrosive, the corrosion caused by the lubricating fluid eroding the interface between the coating and the substrate greatly reduces the bonding strength between the coating and the substrate, which makes the service life of the chromium oxide coating much lower than expected.

[0005] CN108177435A discloses a ceramic anilox roller and its preparation process, comprising a roller body, a nickel-chromium alloy layer disposed on the outer surface of the roller body, and a chromium oxide ceramic layer disposed on the outer surface of the nickel-chromium alloy layer, wherein the outer wall of the chromium oxide ceramic layer is provided with a mesh pattern for carrying ink. However, the porosity of the chromium oxide ceramic layer in the ceramic anilox roller is relatively high, and the corrosive agent in the ink will corrode the interface between the coating and the nickel-chromium alloy layer, thereby causing corrosion, reducing the bonding strength between the coating and the nickel-chromium alloy layer, and thus reducing the life of the ceramic anilox roller.

[0006] CN103173710A discloses a ceramic mirror roller, including a roller base, on the surface of which a nickel-chromium alloy bottom layer and a chromium oxide surface layer are sequentially coated by plasma spraying. The thickness of the nickel-chromium alloy bottom layer is 0.12-0.15 mm, and nickel accounts for 80% of the nickel-chromium alloy. The thickness of the chromium oxide surface layer is 0.25-0.35 mm. However, the chromium oxide surface layer in the ceramic mirror roller is obtained by plasma spraying, and the bonding strength and density of the chromium oxide coating are limited, and it is difficult for the chromium oxide coating to fully exert its wear resistance and corrosion resistance protection performance; moreover, the porosity of the chromium oxide ceramic layer in the ceramic mirror roller is relatively high, and the external corrosive agent will corrode the interface between the chromium oxide coating and the nickel-chromium alloy layer during roller coating, thereby causing corrosion, reducing the bonding strength between the coating and the nickel-chromium alloy layer, and reducing the life of the ceramic mirror roller.

[0007] The piston rods with self-lubricating coating disclosed in the prior art all have certain defects. The density of the chromium oxide coating on the surface of the piston rod and its bonding strength with the substrate are low, which leads to the problem that the corrosion resistance and wear resistance of the chromium oxide coating are poor, that is, the lubricating liquid easily passes through the chromium oxide coating with high porosity, thereby corroding the interface between the chromium oxide coating and the substrate, resulting in the problem that the structural strength of the chromium oxide coating and the substrate deteriorates. Therefore, it is very important to develop and design a new type of piston rod with self-lubricating coating and a preparation method thereof. Summary of the invention

[0008] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a piston rod with a self-lubricating coating and a preparation method thereof. In the piston rod with a self-lubricating coating provided by the present invention, the chromium oxide film layer has a relatively high density. The dense chromium oxide film layer not only has strong corrosion resistance and wear resistance, but can also effectively block and isolate the infiltration of corrosive grease, thereby ensuring that the bonding strength between the chromium oxide layer and the substrate is not affected by corrosion factors; in addition, the surface of the chromium oxide layer has at least one pit, which increases the complexity of the surface of the chromium oxide layer, so that the contact surface has a horizontal force-bearing surface and also has longitudinal pits, which can allow the lubricating filler to be filled therein, thereby playing a good lubricating role, thereby further improving the lubrication performance of the piston rod.

[0009] To achieve this object, the present invention adopts the following technical solutions: In a first aspect, the present invention provides a piston rod having a self-lubricating coating, the piston rod comprising a substrate and a chromium oxide layer which are stacked; The chromium oxide layer comprises a stacked chromium oxide inner layer and a chromium oxide film layer, wherein the chromium oxide inner layer is located close to the substrate, and the density of the chromium oxide film layer is higher than that of the chromium oxide inner layer; The surface of the chromium oxide layer has at least one pit, and each of the pits is filled with a lubricating filler.

[0010] In the piston rod with a self-lubricating coating provided by the present invention, the chromium oxide film layer has a relatively high density. The dense chromium oxide film layer not only has strong corrosion resistance and wear resistance, but can also effectively block and isolate the infiltration of corrosive grease, thereby ensuring that the bonding strength between the chromium oxide layer and the substrate is not affected by corrosion factors; in addition, the surface of the chromium oxide layer has at least one pit, which increases the complexity of the surface of the chromium oxide layer, so that the contact surface has a horizontal force-bearing surface and also has longitudinal pits, which can allow the lubricating filler to be filled therein, thereby playing a good lubricating role, thereby further improving the lubrication performance of the piston rod.

[0011] Preferably, a nickel-chromium base layer is provided between the substrate and the chromium oxide layer.

[0012] Preferably, the thickness of the nickel-chromium base layer is 0.1-0.15 mm, for example, 0.1 mm, 0.11 mm, 0.12 mm, 0.13 mm, 0.14 mm or 0.15 mm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0013] Preferably, the thickness of the chromium oxide layer is 0.2-0.5 mm, for example, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm or 0.5 mm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0014] The thickness of the chromium oxide layer in the present invention is the sum of the thickness of the chromium oxide inner layer and the chromium oxide film layer in the piston rod.

[0015] Preferably, the depth of the pits on the surface of the chromium oxide layer is 0.05-0.15 mm, for example, it can be 0.1 mm, 0.11 mm, 0.12 mm, 0.13 mm, 0.14 mm or 0.15 mm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0016] Preferably, the shape of the pits in the cross section of the chromium oxide layer is truncated cone, cone, cylinder, prism, pyramid or prism, preferably hexagonal prism.

[0017] Preferably, the lubricating filler comprises a chromium oxide filler having a porosity of 5 to 20%. The porosity may be, for example, 5%, 8%, 10%, 12%, 15%, 18% or 20%, but is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable.

[0018] In the piston rod provided by the present invention, since the chromium oxide filler with a porosity of 5-20% has open pores, it is beneficial to the storage of lubricating grease, and is beneficial to maintaining the continuity of the lubricating oil film of the coated component piston rod under friction and wear conditions, reducing the friction coefficient, thereby improving the lubrication performance of the piston rod.

[0019] Preferably, the friction coefficient of the chromium oxide filler is 0.1-0.25, for example, it can be 0.1, 0.12, 0.15, 0.18, 0.2, 0.22 or 0.25, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0020] Preferably, the lubricating filler comprises a Mo metal filler.

[0021] Molybdenum (Mo) has the characteristics of high strength, high hardness and excellent mechanical properties, and can still maintain high strength and hardness at high temperatures; in addition, molybdenum is a refractory metal with low metallic activity, has a high melting point and boiling point, has good corrosion resistance to acids, alkalis and molten metals, and has good thermal and electrical conductivity; in addition, molybdenum is also a good anti-friction material that can effectively reduce the friction coefficient. When liquid lubrication is difficult to use, the use of thermal sprayed molybdenum coating can reduce friction and extend service life.

[0022] In the piston rod provided by the present invention, Mo metal filler is used as the lubricating filler. The lubricating property and corrosion resistance of the Mo metal filler can improve the defect of corrosion resistance of the bonding interface between the chromium oxide layer and the substrate. In addition, the presence of open gaps in the Mo metal filler is conducive to the storage of the wetting of lubricating grease, and is conducive to maintaining the continuity of the lubricating oil film of the piston rod of the coated component under friction and wear conditions, thereby reducing the friction coefficient, reducing the wear rate of the piston rod, and greatly improving the service life of the piston rod.

[0023] Preferably, the friction coefficient of the Mo metal filler is not higher than 0.2, for example, it can be 0.2, 0.18, 0.16, 0.14, 0.12 or 0.1, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0024] Preferably, the lubricating filler comprises a polytetrafluoroethylene filler.

[0025] Polytetrafluoroethylene filler has a series of excellent properties, such as low friction coefficient, hydrophobicity, excellent aging resistance, heat resistance and weather resistance.

[0026] In the piston rod provided by the present invention, polytetrafluoroethylene filler is used as a lubricating filler, which is beneficial for the piston rod to maintain high lubricity while improving the friction and wear resistance and reduce the film material coefficient, thereby significantly improving the service life of the piston rod.

[0027] Preferably, the friction coefficient of the polytetrafluoroethylene filler is 0.1-0.25, for example, it can be 0.1, 0.12, 0.15, 0.18, 0.2, 0.22 or 0.25, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0028] In a second aspect, the present invention provides a method for preparing the piston rod according to the first aspect, the method comprising: A chromium oxide layer is prepared on the surface of a substrate, and the surface of the obtained chromium oxide layer is laser engraved by a laser engraving method so that the surface of the chromium oxide layer has at least one pit, and then a lubricating filler is prepared in the pit on the surface of the chromium oxide layer to obtain the piston rod.

[0029] Laser engraving technology is based on CNC technology and uses laser as the processing medium. The physical transformation of the processing material into instantaneous melting and vaporization under the irradiation of laser engraving can enable laser engraving to achieve the processing purpose.

[0030] In the present invention, the surface profile of the open wire thread is engraved by laser (i.e., at least one pit is formed on the surface of the chromium oxide layer), thereby forming a holding space for the subsequent lubricating filler. While increasing the complexity of the surface of the chromium oxide layer, the contact surface has both a horizontal force-bearing surface and a longitudinal pit, so that the lubricating filler can be filled therein, thereby achieving a good lubricating effect.

[0031] When laser engraving is performed in the present invention, a molten pool is formed in a very short time on the surface of a certain depth of the chromium oxide layer originally containing voids due to the high-energy laser ablation. After rapid cooling, the original voids in the chromium oxide layer disappear, thereby forming a dense chromium oxide film layer on the surface of a certain depth of the chromium oxide layer after engraving. This dense chromium oxide film layer can effectively block and isolate the infiltration of corrosive grease, thereby ensuring that the bonding strength between the chromium oxide layer and the substrate is not affected by corrosion factors.

[0032] Preferably, the preparation method further comprises: pre-treating the substrate before preparing the chromium oxide layer.

[0033] Preferably, the pre-treatment comprises: cleaning the substrate with alcohol, drying it at 60-100° C., and then performing sandblasting and activation treatment in sequence.

[0034] The temperature of the pretreatment drying of the present invention is 60-100°C, for example, it can be 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C or 100°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0035] Preferably, the pressure in the sandblasting roughening is 0.1-0.6 MPa, the sandblasting distance is 30-120 mm, the sandblasting angle is 70-90°, and the sandblasting material is 24-46 mesh alumina white corundum sand particles.

[0036] The sandblasting roughening pressure in the present invention is 0.1-0.6 MPa, for example, it can be 0.1 MPa, 0.2 MPa, 0.3 MPa, 0.4 MPa, 0.5 MPa or 0.6 MPa, but it is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0037] Preferably, the preparation method further comprises: preparing a nickel-chromium base layer between the pretreatment and the preparation of the chromium oxide layer, and the method for preparing the nickel-chromium base layer comprises atmospheric plasma spraying.

[0038] Preferably, the process parameters of atmospheric plasma spraying in preparing the nickel-chromium base layer are: current of 300~550A, voltage of 40~70V, auxiliary gas flow rate of 1~10L / min, scanning speed of 120~180m / min, powder feeding amount of 20~150g / min, powder feeding carrier gas flow rate of 2.0~12.0L / min, main gas flow rate of 25~70L / min, spraying distance of 100~200mm, spraying angle of 70~90°, during the spraying process, the temperature of the substrate surface is 50~150°C, and the powder material is a nickel-chromium mixed powder with an average particle size of 45~106μm and a Ni mass fraction of 75-80wt%.

[0039] The process parameters of atmospheric plasma spraying in the preparation of the nickel-chromium base layer of the present invention include a current of 300-550A, for example, 300A, 350A, 400A, 450A, 500A or 550A, but are not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0040] The voltage in the process parameters of atmospheric plasma spraying in preparing the nickel-chromium base layer of the present invention is 40-70V, for example, it can be 40V, 45V, 50V, 55V, 60V, 65V or 70V, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0041] The auxiliary gas flow rate in the process parameters of atmospheric plasma spraying in preparing the nickel-chromium base layer of the present invention is 1-10 L / min, for example, it can be 1 L / min, 2 L / min, 3 L / min, 4 L / min, 5 L / min, 6 L / min, 7 L / min, 8 L / min, 9 L / min or 10 L / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0042] The scanning speed in the process parameters of atmospheric plasma spraying in preparing the nickel-chromium base layer of the present invention is 120-180 m / min, for example, it can be 120 m / min, 130 m / min, 140 m / min, 150 m / min, 160 m / min, 170 m / min or 180 m / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0043] The process parameters of atmospheric plasma spraying in the preparation of the nickel-chromium base layer of the present invention include a powder feeding rate of 20 to 150 g / min, for example, 20 g / min, 40 g / min, 60 g / min, 80 g / min, 100 g / min, 120 g / min, 140 g / min or 150 g / min, but are not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0044] The process parameters of atmospheric plasma spraying in the preparation of the nickel-chromium base layer of the present invention include a powder carrier gas flow rate of 2.0 to 12.0 L / min, for example, 2.0 L / min, 4.0 L / min, 6.0 L / min, 8.0 L / min, 10.0 L / min or 12.0 L / min, but are not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0045] The main gas flow rate in the process parameters of atmospheric plasma spraying in preparing the nickel-chromium base layer of the present invention is 25~70L / min, for example, it can be 25L / min, 35L / min, 45L / min, 55L / min, 65L / min or 70L / min, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0046] The spraying distance in the process parameters of atmospheric plasma spraying in preparing the nickel-chromium base layer of the present invention is 100-200 mm, for example, it can be 100 mm, 120 mm, 140 mm, 160 mm, 180 mm or 200 mm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0047] The spraying angle in the process parameters of atmospheric plasma spraying in preparing the nickel-chromium base layer of the present invention is 70-90°, for example, it can be 70°, 72°, 75°, 77°, 80°, 82°, 85°, 87° or 90°, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0048] The temperature of the substrate surface in the process parameters of atmospheric plasma spraying in preparing the nickel-chromium base layer of the present invention is 50-150°C, for example, it can be 50°C, 70°C, 90°C, 100°C, 120°C, 140°C or 150°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0049] The average particle size of the nickel-chromium mixed powder in the process parameters of atmospheric plasma spraying in preparing the nickel-chromium base layer of the present invention is 45~106μm, for example, it can be 45μm, 55μm, 65μm, 75μm, 85μm, 95μm, 105μm or 106μm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0050] In the process parameters of atmospheric plasma spraying in the preparation of the nickel-chromium base layer of the present invention, the mass fraction of Ni in the nickel-chromium mixed powder is 75-80wt%, for example, it can be 75wt%, 76wt%, 77wt%, 78wt%, 79wt% or 80wt%, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0051] Preferably, the method of preparing the chromium oxide layer comprises atmospheric plasma spraying.

[0052] Preferably, the process parameters of atmospheric plasma spraying in preparing the chromium oxide layer are: current of 300~650A, voltage of 40~80V, auxiliary gas flow rate of 1~15L / min, scanning speed of 120~180m / min, powder feeding amount of 20~150g / min, powder feeding carrier gas flow rate of 2.0~12.0L / min, main gas flow rate of 25~75L / min, spraying distance of 100~250mm, spraying angle of 70~90°, during the spraying process, the temperature of the substrate surface is 50~150°C, and the powder material uses chromium trioxide powder with an average particle size of 22~45μm and a purity higher than 99.5wt%.

[0053] In the process parameters of atmospheric plasma spraying for preparing the chromium oxide layer of the present invention, the current is 300~650A, for example, it can be 300A, 350A, 400A, 450A, 500A, 550A, 600A or 650A, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0054] The voltage in the process parameters of atmospheric plasma spraying in preparing the chromium oxide layer of the present invention is 40~80V, for example, it can be 40V, 45V, 50V, 55V, 60V, 65V, 70V, 75V or 80V, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0055] The auxiliary gas flow rate in the process parameters of atmospheric plasma spraying in preparing the chromium oxide layer of the present invention is 1~15L / min, for example, it can be 1L / min, 2L / min, 3L / min, 4L / min, 5L / min, 6L / min, 7L / min, 8L / min, 9L / min, 10L / min, 12L / min or 15L / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0056] The scanning speed in the process parameters of atmospheric plasma spraying in preparing the chromium oxide layer of the present invention is 120~180m / min, for example, it can be 120m / min, 130m / min, 140m / min, 150m / min, 160m / min, 170m / min or 180m / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0057] The process parameters of atmospheric plasma spraying in the preparation of the chromium oxide layer of the present invention include a powder feeding rate of 20 to 150 g / min, for example, 20 g / min, 40 g / min, 60 g / min, 80 g / min, 100 g / min, 120 g / min, 140 g / min or 150 g / min, but are not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0058] In the process parameters of atmospheric plasma spraying for preparing the chromium oxide layer of the present invention, the powder carrier gas flow rate is 2.0~12.0L / min, for example, it can be 2.0L / min, 4.0L / min, 6.0L / min, 8.0L / min, 10.0L / min or 12.0L / min, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0059] The main gas flow rate in the process parameters of atmospheric plasma spraying in preparing the chromium oxide layer of the present invention is 25~75L / min, for example, it can be 25L / min, 35L / min, 45L / min, 55L / min, 65L / min, 70L / min or 75L / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0060] In the process parameters of atmospheric plasma spraying for preparing the chromium oxide layer of the present invention, the spraying distance is 100-250 mm, for example, it can be 100 mm, 120 mm, 140 mm, 160 mm, 180 mm, 200 mm, 220 mm or 250 mm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0061] The spraying angle in the process parameters of atmospheric plasma spraying in preparing the chromium oxide layer of the present invention is 70-90°, for example, it can be 70°, 72°, 75°, 77°, 80°, 82°, 85°, 87° or 90°, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0062] In the process parameters of atmospheric plasma spraying in the preparation of the chromium oxide layer of the present invention, the temperature of the substrate surface is 50-150°C, for example, it can be 50°C, 70°C, 90°C, 100°C, 120°C, 140°C or 150°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0063] In the process parameters of atmospheric plasma spraying in the preparation of the chromium oxide layer of the present invention, the average particle size of the chromium trioxide powder is 22~45μm, for example, it can be 22μm, 25μm, 30μm, 35μm, 40μm or 45μm, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0064] In the process parameters of atmospheric plasma spraying in the preparation of the chromium oxide layer of the present invention, the purity of the chromium trioxide powder is higher than 99.5wt%, for example, it can be 99.6wt%, 99.7wt%, 99.8wt%, 99.9wt% or 99.99wt%, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0065] Preferably, the preparation of the chromium oxide layer and the laser engraving further include grinding and surface polishing performed in sequence.

[0066] Preferably, the grinding process includes: grinding the surface of the chromium oxide layer with a coarse grinding wheel of 100-140 mesh, for example, it can be 100 mesh, 105 mesh, 110 mesh, 115 mesh, 120 mesh, 125 mesh, 130 mesh, 135 mesh or 140 mesh, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0067] Preferably, the surface polishing comprises: polishing the ground chromium oxide layer with a diamond polishing belt.

[0068] Preferably, the thickness of the polished chromium oxide layer obtained after the surface polishing is 0.3-0.5 mm, for example, it can be 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm or 0.5 mm, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0069] Preferably, the process parameters of the laser engraving are: the focal length of the spot is 10-15mm, the laser pulse frequency is 10-100KHZ, the pulse width is 10-150ns, the laser beam scanning rate is 300-500mm / s, the laser beam power is 15-25w, the engraving angle is 85-90°, the engraving depth is 0.05-0.2mm, the engraving shape is a mesh shape and adopts an open spiral line structure, the engraving step is 0.08-0.12mm, and argon or CO is used. 2 Gas is used as the gas for laser engraving.

[0070] The focal length of the laser spot in the process parameters of laser engraving in the present invention is 10-15 mm, for example, it can be 10 mm, 11 mm, 12 mm, 13 mm, 14 mm or 15 mm, but it is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0071] The laser pulse frequency in the process parameters of laser engraving in the present invention is 10~100KHZ, for example, it can be 10KHZ, 20KHZ, 30KHZ, 40KHZ, 50KHZ, 60KHZ, 70KHZ, 80KHZ, 90KHZ or 100KHZ, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0072] The pulse width of the laser engraving process parameters in the present invention is 10-150ns, for example, it can be 10ns, 20ns, 30ns, 40ns, 50ns, 60ns, 70ns, 80ns, 90ns, 100ns, 110ns, 120ns, 130ns, 140ns or 150ns, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0073] The laser beam scanning rate in the process parameters of laser engraving in the present invention is 300~500mm / s, for example, it can be 300mm / s, 320mm / s, 350mm / s, 380mm / s, 400mm / s, 420mm / s, 450mm / s, 480mm / s or 500mm / s, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0074] The laser beam power in the laser engraving process parameters of the present invention is 15~25W, for example, it can be 15W, 16W, 18W, 20W, 21W, 23W or 25W, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0075] The engraving angle in the process parameters of laser engraving in the present invention is 85-90°, for example, it can be 85°, 86°, 87°, 88°, 89° or 90°, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0076] The engraving depth in the process parameters of laser engraving in the present invention is 0.05~0.2mm, for example, it can be 0.05mm, 0.06mm, 0.07mm, 0.08mm, 0.09mm, 0.1mm, 0.1mm, 0.12mm, 0.14mm, 0.16mm, 0.18mm or 0.2mm, but it is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0077] The engraving step distance in the process parameters of laser engraving in the present invention is 0.08-0.12 mm, for example, it can be 0.08 mm, 0.09 mm, 0.1 mm, 0.11 mm or 0.12 mm, but it is not limited to the listed values, and other values ​​not listed in the numerical range are also applicable.

[0078] Preferably, the method for preparing the lubricating filler comprises: depositing a chromium oxide-polyester composite coating on the surface of the laser-engraved chromium oxide layer, performing grinding treatment until the surface of the chromium oxide layer and the surface of the chromium oxide-polyester composite coating are located in the same plane, and then removing the polyester by heat treatment to obtain a lubricating filler located in the pits on the surface of the chromium oxide layer.

[0079] In the present invention, after a chromium oxide-polyester composite coating is deposited on the surface of the laser-engraved chromium oxide layer, a heat treatment is performed to decompose and evaporate the polyester in the chromium oxide-polyester composite coating, so that only chromium oxide is left in the chromium oxide-polyester composite coating, pores are formed at the position of the polyester, and a chromium oxide filler with a porosity of 5-20% is obtained as a lubricating filler.

[0080] Preferably, the deposition method comprises: spraying chromium oxide-polyester composite powder by atmospheric plasma to obtain a chromium oxide-polyester composite coating.

[0081] Preferably, the process parameters of atmospheric plasma spraying in the deposition are: current of 300~600A, voltage of 40~75V, auxiliary gas flow rate of 1~12L / min, scanning speed of 120~180m / min, powder feeding amount of 20~150g / min, powder feeding carrier gas flow rate of 2.0~12.0L / min, main gas flow rate of 25~70L / min, spraying distance of 90~200mm, spraying angle of 70~90°, and during the spraying process, the temperature of the substrate surface is 50~150℃.

[0082] The process parameters of atmospheric plasma spraying in the deposition of the present invention include an electric current of 300-600 A, for example, 300 A, 350 A, 400 A, 450 A, 500 A, 550 A or 600 A, but are not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0083] The voltage in the process parameters of atmospheric plasma spraying in the deposition of the present invention is 40~75V, for example, it can be 40V, 45V, 50V, 55V, 60V, 65V, 70V or 75V, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0084] The auxiliary gas flow rate in the process parameters of atmospheric plasma spraying in the deposition of the present invention is 1~12L / min, for example, it can be 1L / min, 2L / min, 3L / min, 4L / min, 5L / min, 6L / min, 7L / min, 8L / min, 9L / min, 10L / min or 12L / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0085] The scanning speed in the process parameters of atmospheric plasma spraying in the deposition of the present invention is 120~180m / min, for example, it can be 120m / min, 130m / min, 140m / min, 150m / min, 160m / min, 170m / min or 180m / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0086] The process parameters of atmospheric plasma spraying in the deposition of the present invention include a powder feeding rate of 20 to 150 g / min, for example, 20 g / min, 40 g / min, 60 g / min, 80 g / min, 100 g / min, 120 g / min, 140 g / min or 150 g / min, but are not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0087] The process parameters of atmospheric plasma spraying in the deposition of the present invention include a powder carrier gas flow rate of 2.0 to 12.0 L / min, for example, 2.0 L / min, 4.0 L / min, 6.0 L / min, 8.0 L / min, 10.0 L / min or 12.0 L / min, but are not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0088] The main gas flow rate in the process parameters of atmospheric plasma spraying in the deposition of the present invention is 25~70L / min, for example, it can be 20L / min, 25L / min, 35L / min, 45L / min, 55L / min, 65L / min or 70L / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0089] The spraying distance in the process parameters of atmospheric plasma spraying in the deposition of the present invention is 90~200mm, for example, it can be 90mm, 100mm, 120mm, 140mm, 160mm, 180mm or 200mm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0090] The spraying angle in the process parameters of atmospheric plasma spraying in the deposition of the present invention is 70~90°, for example, it can be 70°, 72°, 75°, 77°, 80°, 82°, 85°, 87° or 90°, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0091] The temperature of the substrate surface in the process parameters of atmospheric plasma spraying in the deposition of the present invention is 50~150°C, for example, it can be 50°C, 70°C, 90°C, 100°C, 120°C, 140°C or 150°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0092] Preferably, the method for preparing the chromium oxide-polyester composite powder includes: mechanically mixing chromium oxide powder and polyester powder to obtain a primary mixture, then mixing the obtained primary mixture with a binder, a solvent and a dispersant by high-energy ball milling to obtain a composite powder slurry, and then spray-drying, granulating and screening the obtained composite powder slurry in sequence to obtain the chromium oxide-polyester composite powder.

[0093] Preferably, the rotation speed of the mechanical mixing is 30-60 rpm and the time is 2-4 hours.

[0094] The rotation speed of the mechanical mixing in the present invention is 30-60 rpm, for example, it can be 30 rpm, 35 rpm, 40 rpm, 45 rpm, 50 rpm, 55 rpm or 60 rpm, but it is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0095] The mechanical mixing time of the present invention is 2 to 4 hours, for example, it can be 2 hours, 2.2 hours, 2.5 hours, 2.7 hours, 3 hours, 3.2 hours, 3.5 hours, 3.7 hours or 4 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0096] Preferably, based on the mass of the primary mixture as percentage, the mass fraction of the chromium oxide powder in the primary mixture is 91-95wt%, for example, it can be 91wt%, 92wt%, 93wt%, 94wt% or 95wt%, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable, and the remainder is polyester powder.

[0097] Preferably, the chromium oxide powder is a powder with an average particle size of 22 to 45 μm obtained by agglomerating powder with an average particle size of 100 to 200 nm.

[0098] The powder of 100-200 nm in the present invention may be, for example, 100 nm, 120 nm, 140 nm, 160 nm, 180 nm or 200 nm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0099] The chromium oxide powder in the present invention is agglomerated into a powder with an average particle size of 22 to 45 μm, for example, 22 μm, 25 μm, 30 μm, 35 μm, 40 μm or 45 μm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0100] Preferably, the average particle size of the polyester powder is 45-106 μm, for example, 45 μm, 55 μm, 65 μm, 75 μm, 85 μm, 95 μm, 105 μm or 106 μm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0101] Preferably, the ball milling time in the high-energy ball milling method is 6 to 16 hours, the grinding balls are Φ8 ceramic balls, and the ball milling speed is 100 to 600 rpm.

[0102] The ball milling time in the high-energy ball milling method of the present invention is 6 to 16 hours, for example, it can be 6 hours, 8 hours, 10 hours, 12 hours, 14 hours or 16 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0103] The ball milling speed in the high-energy ball milling method of the present invention is 100-600 rpm, for example, it can be 100 rpm, 200 rpm, 300 rpm, 400 rpm, 500 rpm or 600 rpm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0104] Preferably, in the high-energy ball milling method, the mass ratio of the primary mixture to the binder, the solvent and the dispersant is 100:(2-15):(100-300):(2-12).

[0105] The mass ratio of the primary mixture to the binder in the high energy ball milling method of the present invention is 100:(2-15), for example, it can be 100:2, 100:5, 100:7, 100:10, 100:12 or 100:15, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0106] The mass ratio of the initial mixture to the solvent in the high-energy ball milling method of the present invention is 100:(100~300), for example, it can be 100:100, 100:150, 100:200, 100:250 or 100:300, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0107] The mass ratio of the primary mixture to the dispersant in the high-energy ball milling method of the present invention is 100:(2-12), for example, it can be 100:2, 100:5, 100:7, 100:10 or 100:12, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0108] Preferably, the binder used in preparing the chromium oxide-polyester composite powder comprises polyvinyl alcohol.

[0109] Preferably, the solvent used in preparing the chromium oxide-polyester composite powder includes water.

[0110] Preferably, the dispersant used in preparing the chromium oxide-polyester composite powder comprises polyacrylic acid.

[0111] Preferably, the feed rate in the spray drying granulation is 50-150 mL / min, the air inlet temperature is 200-350°C, and the air outlet temperature is 100-150°C.

[0112] The feed rate in the spray drying granulation of the present invention is 50-150 mL / min, for example, it can be 50 mL / min, 60 mL / min, 80 mL / min, 100 mL / min, 120 mL / min, 140 mL / min or 150 mL / min, but it is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0113] The air inlet temperature in the spray drying granulation of the present invention is 200-350°C, for example, it can be 200°C, 220°C, 240°C, 260°C, 280°C, 300°C or 350°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0114] The outlet temperature in the spray drying granulation of the present invention is 100-150°C, for example, it can be 100°C, 110°C, 120°C, 130°C, 140°C or 150°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0115] Preferably, after the screening, the chromium oxide-polyester composite powder has an average particle size of 30 to 150 μm, for example, it can be 30 μm, 50 μm, 70 μm, 100 μm, 120 μm or 150 μm, but it is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable. Preferably, the chromium oxide-polyester composite powder is 36 to 145 μm.

[0116] Preferably, the grinding process includes: grinding with a 200-280 mesh coarse grinding wheel, for example, 200 mesh, 220 mesh, 240 mesh, 260 mesh or 280 mesh, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0117] Preferably, the heat treatment comprises heating to 350-450° C. at a rate of 3-5° C. / min under an atmospheric pressure and then keeping the temperature for 3-5 hours.

[0118] The heating rate in the heat treatment described in the present invention is 3~5℃ / min, for example, it can be 3℃ / min, 3.5℃ / min, 4℃ / min, 4.5℃ / min or 5℃ / min, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0119] In the heat treatment described in the present invention, the temperature is raised to 350-450°C and then kept warm. For example, it can be 350°C, 370°C, 400°C, 420°C or 450°C, but it is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable.

[0120] In the heat treatment described in the present invention, the temperature is increased and then kept warm for 3 to 5 hours, for example, it can be 3 hours, 3.2 hours, 3.4 hours, 3.6 hours, 3.8 hours, 4 hours, 4.2 hours, 4.4 hours, 4.6 hours, 4.8 hours or 5 hours, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0121] Preferably, the method for preparing the lubricating filler comprises: preparing a Mo metal layer on the surface of the laser-engraved chromium oxide layer and then performing grinding until the surface of the chromium oxide layer and the surface of the Mo metal layer are located in the same plane, thereby obtaining a lubricating filler located in the pits on the surface of the chromium oxide layer.

[0122] Preferably, the method of preparing the Mo metal layer comprises atmospheric plasma spraying.

[0123] Preferably, the process parameters of atmospheric plasma spraying in preparing the Mo metal layer are: current of 500~650A, voltage of 40~75V, auxiliary gas flow rate of 5~12L / min, scanning speed of 120~180m / min, powder feeding amount of 30~70g / min, powder feeding carrier gas flow rate of 2.0~12.0L / min, main gas flow rate of 40~70L / min, spraying distance of 90~200mm, spraying angle of 70~90°, and the temperature of the substrate surface during spraying is 50~150°C.

[0124] In the process parameters of atmospheric plasma spraying in preparing the Mo metal layer in the present invention, the current is 500~650A, for example, it can be 500A, 520A, 550A, 580A, 600A, 620A or 650A, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0125] In the process parameters of atmospheric plasma spraying in preparing the Mo metal layer in the present invention, the voltage is 40~75V, for example, it can be 40V, 45V, 50V, 55V, 60V, 65V, 70V or 75V, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0126] In the process parameters of atmospheric plasma spraying in preparing the Mo metal layer in the present invention, the auxiliary gas flow rate is 5 to 12 L / min, for example, it can be 5 L / min, 6 L / min, 7 L / min, 8 L / min, 9 L / min, 10 L / min or 12 L / min, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0127] In the process parameters of atmospheric plasma spraying in preparing the Mo metal layer in the present invention, the scanning speed is 120~180m / min, for example, it can be 120m / min, 130m / min, 140m / min, 150m / min, 160m / min, 170m / min or 180m / min, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0128] In the process parameters of atmospheric plasma spraying in preparing the Mo metal layer in the present invention, the powder feeding rate is 30-70 g / min, for example, it can be 20 g / min, 30 g / min, 40 g / min, 50 g / min, 60 g / min or 70 g / min, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0129] In the process parameters of atmospheric plasma spraying for preparing the Mo metal layer in the present invention, the powder carrier gas flow rate is 2.0~12.0L / min, for example, it can be 2.0L / min, 4.0L / min, 6.0L / min, 8.0L / min, 10.0L / min or 12.0L / min, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0130] In the process parameters of atmospheric plasma spraying in preparing the Mo metal layer in the present invention, the main gas flow rate is 40~70L / min, for example, it can be 40L / min, 45L / min, 55L / min, 65L / min or 70L / min, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0131] In the process parameters of atmospheric plasma spraying in preparing the Mo metal layer in the present invention, the spraying distance is 90~200mm, for example, it can be 90mm, 100mm, 120mm, 140mm, 160mm, 180mm or 200mm, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0132] In the process parameters of atmospheric plasma spraying in preparing the Mo metal layer in the present invention, the spraying angle is 70~90°, for example, it can be 70°, 72°, 75°, 77°, 80°, 82°, 85°, 87° or 90°, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0133] In the process parameters of atmospheric plasma spraying in preparing the Mo metal layer in the present invention, the temperature of the substrate surface is 50-150°C, for example, it can be 50°C, 70°C, 90°C, 100°C, 120°C, 140°C or 150°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0134] Preferably, the grinding process comprises: grinding with a 200-280 mesh coarse grinding wheel.

[0135] Preferably, the method for preparing the lubricating filler comprises: preparing a polytetrafluoroethylene layer on the surface of the laser-engraved chromium oxide layer by a suspension plasma spraying method and then polishing the layer until the surface of the chromium oxide layer and the surface of the polytetrafluoroethylene layer are located in the same plane, thereby obtaining a lubricating filler located in the pits on the surface of the chromium oxide layer.

[0136] Preferably, the method for preparing the polytetrafluoroethylene layer by plasma spraying comprises: mixing polytetrafluoroethylene, a dispersant and a surfactant to obtain a polytetrafluoroethylene suspension, spraying the obtained polytetrafluoroethylene suspension on the surface of the laser-engraved chromium oxide layer using a plasma spray gun, and then performing a curing treatment to obtain a polytetrafluoroethylene layer.

[0137] Preferably, in the method for preparing the polytetrafluoroethylene layer by plasma spraying, the mixing method comprises using magnetic stirring to initially mix the polytetrafluoroethylene, dispersant and surfactant, and then putting them into a vacuum homogenizer for remixing.

[0138] Preferably, during the remixing, the vacuum degree of the vacuum homogenizer is adjusted to -100 KPa, and the remixing time is 2 to 5 minutes.

[0139] The remixing time of the present invention is 2 to 5 minutes, for example, it can be 2 minutes, 2.5 minutes, 3 minutes, 3.5 minutes, 4 minutes, 4.5 minutes or 5 minutes, but it is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0140] Preferably, based on the mass of the polytetrafluoroethylene suspension as 100%, the mass fraction of polytetrafluoroethylene in the polytetrafluoroethylene suspension is 95-98.5wt%, the mass fraction of the dispersant is 0.5-2.5wt%, and the mass fraction of the surfactant is 1-2.5wt%.

[0141] In the present invention, taking the mass of the polytetrafluoroethylene suspension as 100%, the mass fraction of polytetrafluoroethylene in the polytetrafluoroethylene suspension is 95-98.5wt%, for example, it can be 95wt%, 95.5wt%, 96wt%, 96.5wt%, 97wt%, 97.5wt%, 98wt% or 98.5wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0142] In the present invention, based on the mass of the polytetrafluoroethylene suspension as 100%, the mass fraction of the dispersant in the polytetrafluoroethylene suspension is 0.5-2.5wt%, for example, it can be 0.5wt%, 1wt%, 1.5wt%, 2wt% or 2.5wt%, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0143] In the present invention, based on the mass of the polytetrafluoroethylene suspension as 100%, the mass fraction of the surfactant is 1-2.5wt%, for example, it can be 1wt%, 1.2wt%, 1.5wt%, 1.7wt%, 2wt%, 2.2wt% or 2.5wt%, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0144] Preferably, the solid content of the polytetrafluoroethylene suspension is 40-60%, for example, it can be 40%, 42%, 45%, 47%, 50%, 52%, 55%, 57% or 60%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0145] Preferably, the average particle size of the polytetrafluoroethylene is 150-300 nm, for example, 150 nm, 180 nm, 200 nm, 220 nm, 250 nm, 280 nm or 300 nm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0146] Preferably, the dispersant in the polytetrafluoroethylene layer prepared by plasma spraying comprises 2,2,6,6-tetramethylpiperidinyl oxide and / or hydroxyanisole.

[0147] Preferably, the surfactant used in the polytetrafluoroethylene layer prepared by plasma spraying is a non-ionic fluorocarbon surfactant.

[0148] Preferably, the process parameters for spraying the polytetrafluoroethylene suspension are: current of 200~500A, voltage of 35~60V, auxiliary gas flow of 1~12L / min, scanning speed of 80~120m / min, powder feeding amount of 35~80mL / min, main gas flow of 25~70L / min, spraying distance of 90~150mm, spraying angle of 70~90°, and the temperature of the substrate surface during spraying is 50~150°C.

[0149] The current in the process parameters of the polytetrafluoroethylene suspension spraying described in the present invention is 200~500A, for example, it can be 200A, 250A, 300A, 350A, 400A, 450A or 500A, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0150] The voltage in the process parameters of the polytetrafluoroethylene suspension spraying described in the present invention is 35~60V, for example, it can be 30V, 35V, 40V, 45V, 50V, 55V or 60V, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0151] The auxiliary gas flow rate in the process parameters of the polytetrafluoroethylene suspension spraying in the present invention is 1~12L / min, for example, it can be 1L / min, 2L / min, 3L / min, 4L / min, 5L / min, 6L / min, 7L / min, 8L / min, 9L / min, 10L / min or 12L / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0152] The scanning speed in the process parameters of the polytetrafluoroethylene suspension spraying in the present invention is 80~120m / min, for example, it can be 120m / min, 130m / min, 140m / min, 150m / min, 160m / min, 170m / min or 180m / min, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0153] The powder feeding rate in the process parameters of the polytetrafluoroethylene suspension spraying described in the present invention is 35~80mL / min, for example, it can be 30ml / min, 40ml / min, 50ml / min, 60ml / min, 70ml / min or 80ml / min, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0154] The main gas flow rate in the process parameters of the polytetrafluoroethylene suspension spraying described in the present invention is 25~70L / min, for example, it can be 20L / min, 25L / min, 35L / min, 45L / min, 55L / min, 65L / min or 70L / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0155] The spraying distance in the process parameters of the polytetrafluoroethylene suspension spraying described in the present invention is 90~150mm, for example, it can be 90mm, 100mm, 120mm, 140mm or 150mm, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0156] The spraying angle of the polytetrafluoroethylene suspension spraying process parameters in the present invention is 70-90°, for example, it can be 70°, 72°, 75°, 77°, 80°, 82°, 85°, 87° or 90°, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0157] The temperature of the substrate surface in the process parameters of the polytetrafluoroethylene suspension spraying described in the present invention is 50~150°C, for example, it can be 50°C, 70°C, 90°C, 100°C, 120°C, 140°C or 150°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0158] Preferably, the curing treatment comprises: heating to 180-250° C. at a rate of 1-5° C. / min under an atmospheric pressure, then keeping the temperature for 2-4 hours, and then cooling in the furnace.

[0159] In the curing process described in the present invention, the temperature is increased at a rate of 1 to 5°C / min, for example, 1°C / min, 2°C / min, 3°C / min, 4°C / min or 5°C / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0160] In the curing process of the present invention, the temperature is raised to 180-250°C and then kept warm. For example, it can be 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C or 250°C, but it is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable.

[0161] The curing treatment of the present invention is kept warm for 2 to 4 hours, for example, 2 hours, 2.2 hours, 2.5 hours, 2.8 hours, 3 hours, 3.2 hours, 3.5 hours, 3.8 hours or 4 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0162] Preferably, the polishing process includes: polishing with 200-280 mesh diamond sandpaper, for example, it can be 200 mesh, 210 mesh, 220 mesh, 230 mesh, 240 mesh, 250 mesh, 260 mesh, 270 mesh or 280 mesh, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0163] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0164] Compared with the prior art, the present invention has the following beneficial effects: (1) In the piston rod with a self-lubricating coating provided by the present invention, the chromium oxide film layer has a high density. The dense chromium oxide film layer not only has strong corrosion resistance and wear resistance, but also can effectively block and isolate the infiltration of corrosive grease, thereby ensuring that the bonding strength between the chromium oxide layer and the substrate is not affected by corrosion factors; (2) The surface of the chromium oxide layer in the piston rod provided by the present invention has at least one pit, which increases the complexity of the surface of the chromium oxide layer, so that the contact surface has a horizontal force-bearing surface and also has a longitudinal pit, which can allow the lubricating filler to be filled therein, thereby playing a good lubricating role, thereby further improving the lubrication performance of the piston rod; (3) In the piston rod provided by the present invention, since the chromium oxide filler with a porosity of 5-20% has open pores, it is beneficial to the storage of lubricating grease, and it is beneficial to maintain the continuity of the lubricating oil film of the coated component piston rod under friction and wear conditions, reduce the friction coefficient, and thus improve the lubrication performance of the piston rod; (4) In the piston rod provided by the present invention, Mo metal filler is used as the lubricating filler. The lubricating property and corrosion resistance of Mo metal filler can improve the defect of corrosion resistance of the bonding interface between the chromium oxide layer and the substrate; in addition, the open gaps in the Mo metal filler are conducive to the storage of the wetting of lubricating grease, and are conducive to maintaining the continuity of the lubricating oil film of the coated component piston rod under friction and wear conditions, thereby reducing the friction coefficient, reducing the wear rate of the piston rod, and greatly improving the service life of the piston rod; (5) In the piston rod provided by the present invention, polytetrafluoroethylene filler is used as the lubricating filler, which is beneficial for the piston rod to maintain high lubricity while improving the friction and wear resistance and reduce the film material coefficient, thereby significantly improving the service life of the piston rod; (6) In the present invention, the surface profile of the open thread is engraved by laser (i.e., at least one pit is formed on the surface of the chromium oxide layer), thereby forming a space for the subsequent lubricating filler. While increasing the complexity of the surface of the chromium oxide layer, the contact surface has a horizontal force-bearing surface and a longitudinal pit, so that the lubricating filler can be filled therein, thereby achieving a good lubricating effect; (7) When laser engraving is performed in the present invention, a molten pool is formed in a very short time on the surface of a certain depth of the chromium oxide layer that originally contained voids due to the high-energy laser ablation. After rapid cooling, the original voids in the chromium oxide layer disappear, thereby forming a dense chromium oxide film layer on the surface of a certain depth of the chromium oxide layer after engraving. This dense chromium oxide film layer can effectively block and isolate the infiltration of corrosive grease, thereby ensuring that the bonding strength between the chromium oxide layer and the substrate is not affected by corrosion factors. BRIEF DESCRIPTION OF THE DRAWINGS

[0165] Figure 1 Schematic diagram of the structure of the piston rod with self-lubricating coating in Examples 1 to 13.

[0166] Figure 2 is a SEM image of the surface of the chromium oxide layer after laser engraving in Example 1.

[0167] Figure 3 : is a SEM image of the chromium oxide-polyester composite powder obtained in step (6) of the preparation method in Example 1.

[0168] Figure 4 It is a schematic diagram of the structure when the chromium oxide-polyester composite coating is obtained in step (6) of the preparation method in Example 1.

[0169] Among them, 1-substrate; 2-nickel-chromium base layer; 3-chromium oxide layer; 4-lubricating filler; 5-chromium oxide-polyester composite coating. DETAILED DESCRIPTION

[0170] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0171] Embodiment 1: This embodiment provides a piston rod with a self-lubricating coating, such as Figure 1 As shown, the piston rod comprises a laminated substrate 1, a nickel-chromium base layer 2 with a thickness of 0.12 mm, and a chromium oxide layer 3 with a thickness of 0.3 mm; The chromium oxide layer 3 includes a stacked chromium oxide inner layer and a chromium oxide film layer, wherein the chromium oxide inner layer is located close to the substrate 1, and the density of the chromium oxide film layer is higher than that of the chromium oxide inner layer; The surface of the chromium oxide layer 3 has at least one pit with a depth of 0.1 mm, each of which is filled with a lubricating filler 4, and the shape of the pit in the cross section of the chromium oxide layer 3 is a hexagonal prism; The lubricating filler 4 includes a chromium oxide filler having a porosity of 10% and a friction coefficient of 0.15.

[0172] The preparation method of the piston rod comprises: (1) Use alcohol to clean the substrate, then dry it at 80°C, and then perform sandblasting and activation treatment in sequence; The blasting pressure during sandblasting roughening is 0.4MPa, the blasting distance is 70mm, the blasting angle is 80°, and the blasting material is 36-mesh aluminum oxide white corundum sand particles; The activation treatment is sandblasting to remove the oxide scale on the substrate surface and expose the new substrate surface; (2) preparing a nickel-chromium base layer 2 on the surface of the activated substrate obtained in step (1) by atmospheric plasma spraying; the process parameters of the atmospheric plasma spraying in preparing the nickel-chromium base layer 2 are: current of 400A, voltage of 55V, auxiliary gas flow rate of 5L / min, scanning speed of 150m / min, powder feeding amount of 80g / min, powder feeding carrier gas flow rate of 7L / min, main gas flow rate of 50L / min, spraying distance of 150mm, spraying angle of 80°, during the spraying process, the temperature of the substrate surface is 100°C, and the powder material is a nickel-chromium mixed powder with an average particle size of 70μm and a Ni mass fraction of 78wt%; (3) preparing a chromium oxide layer 3 on the surface of the nickel-chromium base layer 2 obtained in step (2) by atmospheric plasma spraying; the process parameters of the atmospheric plasma spraying in preparing the chromium oxide layer 3 are as follows: current of 500 A, voltage of 60 V, auxiliary gas flow rate of 8 L / min, scanning speed of 150 m / min, powder feeding amount of 80 g / min, powder feeding carrier gas flow rate of 7.0 L / min, main gas flow rate of 50 L / min, spraying distance of 180 mm, spraying angle of 80°, during the spraying process, the temperature of the substrate surface is 100° C. The powder material is chromium trioxide powder with an average particle size of 35 μm and a purity higher than 99.5 wt%; (4) grinding the surface of the chromium oxide layer 3 obtained in step (3) with a 120-mesh coarse grinding wheel, and then polishing the ground chromium oxide layer 3 with a diamond polishing belt to obtain a polished chromium oxide layer 3 with a thickness of 0.32 mm; (5) The surface of the polished chromium oxide layer 3 obtained in step (4) is laser engraved by a laser engraving method, so that the surface of the chromium oxide layer 3 has at least one pit; the process parameters of the laser engraving are: the focal length of the spot is 12 mm, the laser pulse frequency is 50 KHz, the pulse width is 75 ns, the laser beam scanning rate is 400 mm / s, the laser beam power is 20 W, the engraving angle is 88°, the engraving depth is 0.12 mm, the engraving shape is a mesh shape and adopts an open spiral line structure, the engraving step is 0.10 mm, and argon or CO is used. 2 Gas is used as the gas for laser engraving; (6) In step (5), the Figure 2 The surface of the laser engraved chromium oxide layer 3 shown in the scanning electron microscope test is sprayed by atmospheric plasma as shown in the following figure: Figure 3 The chromium oxide-polyester composite powder shown in the scanning electron microscope test was obtained as shown in the figure. Figure 4 The chromium oxide-polyester composite coating 5 shown is then ground with a 240-mesh coarse grinding wheel until the surface of the chromium oxide layer 3 and the surface of the chromium oxide-polyester composite coating 5 are located in the same plane, and then the temperature is raised to 400°C at a rate of 4°C / min under one atmosphere, and then the temperature is kept for 4 hours before the polyester is removed to obtain the lubricating filler 4 located in the pit on the surface of the chromium oxide layer 3, thereby obtaining the piston rod with the self-lubricating coating; The process parameters of atmospheric plasma spraying of chromium oxide-polyester composite powder are: current 500A, voltage 60V, auxiliary gas flow rate 6L / min, scanning speed 150m / min, powder feeding amount 100g / min, powder feeding carrier gas flow rate 7.0L / min, main gas flow rate 50L / min, spraying distance 150mm, spraying angle 80°, and the temperature of the substrate surface during spraying is 100℃; The method for preparing the chromium oxide-polyester composite powder comprises: mechanically mixing chromium oxide powder (powder with an average particle size of 35 μm obtained by agglomerating powder with an average particle size of 150 nm) and polyester powder with an average particle size of 75 μm at a rotation speed of 45 rpm for 3 hours to obtain a primary mixture, then using a high-energy ball milling method to ball-mill the primary mixture with a mass ratio of 100:8:200:7 with polyvinyl alcohol, water and polyacrylic acid at a rotation speed of 350 rpm for 10 hours to obtain a composite powder slurry, and then spray-drying granulation (feeding speed of 100 mL / min, air inlet temperature of 250° C., air outlet temperature of 125° C.) and sieving the obtained composite powder slurry in sequence to obtain a chromium oxide-polyester composite powder with an average particle size of 90 μm.

[0173] Embodiment 2: This embodiment provides a piston rod with a self-lubricating coating, the piston rod comprising a laminated substrate 1, a nickel-chromium base layer 2 with a thickness of 0.12 mm, and a chromium oxide layer 3 with a thickness of 0.4 mm; The chromium oxide layer 3 includes a stacked chromium oxide inner layer and a chromium oxide film layer, wherein the chromium oxide inner layer is located close to the substrate 1, and the density of the chromium oxide film layer is higher than that of the chromium oxide inner layer; The surface of the chromium oxide layer 3 has at least one pit with a depth of 0.12 mm, each of which is filled with a lubricating filler 4, and the shape of the pit in the cross section of the chromium oxide layer 3 is a truncated cone; The lubricating filler 4 comprises a chromium oxide filler having a porosity of 15% and a friction coefficient of 0.2.

[0174] The preparation method of the piston rod comprises: (1) Use alcohol to clean the substrate, then dry it at 80°C, and then perform sandblasting and activation treatment in sequence; The blasting pressure during sandblasting roughening is 0.5MPa, the blasting distance is 50mm, the blasting angle is 75°, and the blasting material is 30-mesh aluminum oxide white corundum sand particles; The activation treatment is sandblasting to remove the oxide skin on the surface of the substrate and expose a new surface of the substrate; (2) preparing a nickel-chromium base layer 2 on the surface of the activated substrate obtained in step (1) by atmospheric plasma spraying; the process parameters of the atmospheric plasma spraying in preparing the nickel-chromium base layer 2 are: current of 400A, voltage of 50V, auxiliary gas flow rate of 8L / min, scanning speed of 170m / min, powder feeding amount of 120g / min, powder feeding carrier gas flow rate of 10.0L / min, main gas flow rate of 60L / min, spraying distance of 120mm, spraying angle of 75°, during the spraying process, the temperature of the substrate surface is 80°C, and the powder material is a nickel-chromium mixed powder with an average particle size of 60μm and a Ni mass fraction of 79wt%; (3) preparing a chromium oxide layer 3 on the surface of the nickel-chromium base layer 2 obtained in step (2) by atmospheric plasma spraying; the process parameters of the atmospheric plasma spraying in preparing the chromium oxide layer 3 are as follows: current of 400 A, voltage of 70 V, auxiliary gas flow rate of 6 L / min, scanning speed of 140 m / min, powder feeding amount of 120 g / min, powder feeding carrier gas flow rate of 10.0 L / min, main gas flow rate of 60 L / min, spraying distance of 200 mm, spraying angle of 78°, during the spraying process, the temperature of the substrate surface is 120° C. The powder material is chromium trioxide powder with an average particle size of 25 μm and a purity higher than 99.5 wt%; (4) grinding the surface of the chromium oxide layer 3 obtained in step (3) with a 130-mesh coarse grinding wheel, and then polishing the ground chromium oxide layer 3 with a diamond polishing belt to obtain a polished chromium oxide layer 3 with a thickness of 0.45 mm; (5) The surface of the polished chromium oxide layer 3 obtained in step (4) is laser engraved by a laser engraving method, so that the surface of the chromium oxide layer 3 has at least one pit; the process parameters of the laser engraving are: the focal length of the spot is 12 mm, the laser pulse frequency is 80 KHZ, the pulse width is 100 ns, the laser beam scanning rate is 450 mm / s, the laser beam power is 18 W, the engraving angle is 86°, the engraving depth is 0.17 mm, the engraving shape is a mesh shape and adopts an open spiral line structure, the engraving step is 0.11 mm, and argon or CO is used as the gas. 2 Gas is used as the gas for laser engraving; (6) The surface of the laser-engraved chromium oxide layer 3 obtained in step (5) is coated with chromium oxide-polyester composite powder by atmospheric plasma spraying to obtain a chromium oxide-polyester composite coating 5, and then ground with a 220-mesh coarse grinding wheel until the surface of the chromium oxide layer 3 and the surface of the chromium oxide-polyester composite coating 5 are located in the same plane, and then heated to 420° C. at a rate of 4.5° C. / min under one atmosphere, and then kept warm for 3.5 hours before removing the polyester to obtain a lubricating filler 4 located in the pit on the surface of the chromium oxide layer 3, thereby obtaining the piston rod with a self-lubricating coating; The process parameters of atmospheric plasma spraying of chromium oxide-polyester composite powder are: current 500A, voltage 65V, auxiliary gas flow rate 10L / min, scanning speed 130m / min, powder feeding amount 40g / min, powder feeding carrier gas flow rate 8.0L / min, main gas flow rate 35L / min, spraying distance 180mm, spraying angle 85°, and during the spraying process, the temperature of the substrate surface is 120℃; The method for preparing the chromium oxide-polyester composite powder comprises: mechanically mixing chromium oxide powder (powder with an average particle size of 40 μm obtained by agglomerating powder with an average particle size of 180 nm) and polyester powder with an average particle size of 80 μm at a rotation speed of 40 rpm for 3.5 hours to obtain a primary mixture, then using a high-energy ball milling method to ball-mill the primary mixture with a mass ratio of 100:12:150:10 with polyvinyl alcohol, water and polyacrylic acid at a rotation speed of 500 rpm for 8 hours to obtain a composite powder slurry, and then spray-drying and granulating the obtained composite powder slurry (feeding speed of 120 mL / min, air inlet temperature of 300° C., air outlet temperature of 140° C.) and sieving in sequence to obtain a chromium oxide-polyester composite powder with an average particle size of 120 μm.

[0175] Embodiment 3: This embodiment provides a piston rod with a self-lubricating coating, the piston rod comprising a laminated substrate 1, a nickel-chromium base layer 2 with a thickness of 0.1 mm, and a chromium oxide layer 3 with a thickness of 0.25 mm; The chromium oxide layer 3 includes a stacked chromium oxide inner layer and a chromium oxide film layer, wherein the chromium oxide inner layer is located close to the substrate 1, and the density of the chromium oxide film layer is higher than that of the chromium oxide inner layer; The surface of the chromium oxide layer 3 has at least one pit with a depth of 0.05 mm, each of which is filled with a lubricating filler 4, and the shape of the pit in the cross section of the chromium oxide layer 3 is a hexagonal prism; The lubricating filler 4 includes a Mo metal filler having a friction coefficient not higher than 0.2.

[0176] The preparation method of the piston rod comprises: (1) Use alcohol to clean the substrate, then dry it at 60°C, and then perform sandblasting and activation treatment in sequence; The blasting pressure during sandblasting roughening is 0.6MPa, the blasting distance is 120mm, the blasting angle is 70°, and the blasting material is 24-mesh alumina white corundum sand particles; The activation treatment is sandblasting to remove the oxide skin on the surface of the substrate and expose a new surface of the substrate; (2) preparing a nickel-chromium base layer 2 on the surface of the activated substrate obtained in step (1) by atmospheric plasma spraying; the process parameters of the atmospheric plasma spraying in preparing the nickel-chromium base layer 2 are: current of 550A, voltage of 70V, auxiliary gas flow rate of 1L / min, scanning speed of 180m / min, powder feeding amount of 150g / min, powder feeding carrier gas flow rate of 2.0L / min, main gas flow rate of 70L / min, spraying distance of 200mm, spraying angle of 70°, during the spraying process, the temperature of the substrate surface is 50°C, and the powder material is a nickel-chromium mixed powder with an average particle size of 106μm and a Ni mass fraction of 80wt%; (3) preparing a chromium oxide layer 3 on the surface of the nickel-chromium base layer 2 obtained in step (2) by atmospheric plasma spraying; the process parameters of the atmospheric plasma spraying in preparing the chromium oxide layer 3 are as follows: current of 650A, voltage of 40V, auxiliary gas flow rate of 15L / min, scanning speed of 180m / min, powder feeding amount of 150g / min, powder feeding carrier gas flow rate of 2.0L / min, main gas flow rate of 75L / min, spraying distance of 250mm, spraying angle of 70°, during the spraying process, the temperature of the substrate surface is 50°C, and the powder material is chromium trioxide powder with an average particle size of 45μm and a purity higher than 99.5wt%; (4) grinding the surface of the chromium oxide layer 3 obtained in step (3) with a 140-mesh coarse grinding wheel, and then polishing the ground chromium oxide layer 3 with a diamond polishing belt to obtain a polished chromium oxide layer 3 with a thickness of 0.3 mm; (5) The surface of the polished chromium oxide layer 3 obtained in step (4) is laser engraved by a laser engraving method, so that the surface of the chromium oxide layer 3 has at least one pit; the process parameters of the laser engraving are: the focal length of the spot is 10 mm, the laser pulse frequency is 100 KHZ, the pulse width is 150 ns, the laser beam scanning rate is 500 mm / s, the laser beam power is 15 W, the engraving angle is 85°, the engraving depth is 0.1 mm, the engraving shape is a mesh shape and adopts an open spiral line structure, the engraving step is 0.08 mm, and argon or CO is used. 2 Gas is used as the gas for laser engraving; (6) After preparing the Mo metal layer on the surface of the laser-engraved chromium oxide layer 3 obtained in step (5) by atmospheric plasma spraying, grinding is performed using a 280-mesh coarse grinding wheel until the surface of the chromium oxide layer 3 and the surface of the Mo metal layer are located in the same plane, thereby obtaining a lubricating filler 4 located in the pit on the surface of the chromium oxide layer 3, thereby obtaining the piston rod with the self-lubricating coating; The process parameters of atmospheric plasma spraying in preparing the Mo metal layer are: current of 650A, voltage of 40V, auxiliary gas flow rate of 12L / min, scanning speed of 180m / min, powder feeding amount of 30g / min, powder feeding carrier gas flow rate of 12.0L / min, main gas flow rate of 70L / min, spraying distance of 200mm, spraying angle of 70°, and the temperature of the substrate surface during spraying is 150°C.

[0177] Embodiment 4: This embodiment provides a piston rod with a self-lubricating coating, the piston rod comprising a laminated substrate 1, a nickel-chromium base layer 2 with a thickness of 0.15 mm, and a chromium oxide layer 3 with a thickness of 0.46 mm; The chromium oxide layer 3 includes a stacked chromium oxide inner layer and a chromium oxide film layer, wherein the chromium oxide inner layer is located close to the substrate 1, and the density of the chromium oxide film layer is higher than that of the chromium oxide inner layer; The surface of the chromium oxide layer 3 has at least one pit with a depth of 0.15 mm, each of which is filled with a lubricating filler 4, and the shape of the pit in the cross section of the chromium oxide layer 3 is a hexagonal prism; The lubricating filler 4 includes a Mo metal filler having a friction coefficient not higher than 0.2.

[0178] The preparation method of the piston rod comprises: (1) Use alcohol to clean the substrate, then dry it at 100°C, and then perform sandblasting and activation treatment in sequence; The blasting pressure during sandblasting roughening is 0.1MPa, the blasting distance is 30mm, the blasting angle is 90°, and the blasting material is 46-mesh aluminum oxide white corundum sand particles; The activation treatment is sandblasting to remove the oxide skin on the surface of the substrate and expose a new surface of the substrate; (2) preparing a nickel-chromium base layer 2 on the surface of the activated substrate obtained in step (1) by atmospheric plasma spraying; the process parameters of the atmospheric plasma spraying in preparing the nickel-chromium base layer 2 are: current of 300A, voltage of 40V, auxiliary gas flow rate of 1L / min, scanning speed of 120m / min, powder feeding amount of 20g / min, powder feeding carrier gas flow rate of 12.0L / min, main gas flow rate of 25L / min, spraying distance of 100mm, spraying angle of 70-90°, during the spraying process, the temperature of the substrate surface is 150°C, and the powder material is a nickel-chromium mixed powder with an average particle size of 45μm and a Ni mass fraction of 75wt%; (3) preparing a chromium oxide layer 3 on the surface of the nickel-chromium base layer 2 obtained in step (2) by atmospheric plasma spraying; the process parameters of the atmospheric plasma spraying in preparing the chromium oxide layer 3 are as follows: current of 300 A, voltage of 80 V, auxiliary gas flow rate of 1 L / min, scanning speed of 120 m / min, powder feeding amount of 20 g / min, powder feeding carrier gas flow rate of 12.0 L / min, main gas flow rate of 25 L / min, spraying distance of 100 mm, spraying angle of 90°, during the spraying process, the temperature of the substrate surface is 150°C, and the powder material is chromium trioxide powder with an average particle size of 22 μm and a purity higher than 99.5 wt%; (4) grinding the surface of the chromium oxide layer 3 obtained in step (3) with a 100-mesh coarse grinding wheel, and then polishing the ground chromium oxide layer 3 with a diamond polishing belt to obtain a polished chromium oxide layer 3 with a thickness of 0.5 mm; (5) The surface of the polished chromium oxide layer 3 obtained in step (4) is laser engraved by a laser engraving method, so that the surface of the chromium oxide layer 3 has at least one pit; the process parameters of the laser engraving are: the focal length of the spot is 15 mm, the laser pulse frequency is 10 KHZ, the pulse width is 10 ns, the laser beam scanning rate is 300 mm / s, the laser beam power is 25 W, the engraving angle is 90°, the engraving depth is 0.15 mm, the engraving shape is a mesh shape and adopts an open spiral line structure, the engraving step is 0.12 mm, and argon or CO is used. 2 Gas is used as the gas for laser engraving; (6) After preparing the Mo metal layer on the surface of the laser-engraved chromium oxide layer 3 obtained in step (5) by atmospheric plasma spraying, grinding is performed using a 200-mesh coarse grinding wheel until the surface of the chromium oxide layer 3 and the surface of the Mo metal layer are located in the same plane, thereby obtaining a lubricating filler 4 located in the pit on the surface of the chromium oxide layer 3, thereby obtaining the piston rod with the self-lubricating coating; The process parameters of atmospheric plasma spraying in preparing the Mo metal layer are: current of 500A, voltage of 75V, auxiliary gas flow rate of 5L / min, scanning speed of 120m / min, powder feeding amount of 70g / min, powder feeding carrier gas flow rate of 2.0L / min, main gas flow rate of 40L / min, spraying distance of 90mm, spraying angle of 90°, and the temperature of the substrate surface during spraying is 50°C.

[0179] Embodiment 5: This embodiment provides a piston rod with a self-lubricating coating, the piston rod comprising a laminated substrate 1, a nickel-chromium base layer 2 with a thickness of 0.12 mm, and a chromium oxide layer 3 with a thickness of 0.3 mm; The chromium oxide layer 3 includes a stacked chromium oxide inner layer and a chromium oxide film layer, wherein the chromium oxide inner layer is located close to the substrate 1, and the density of the chromium oxide film layer is higher than that of the chromium oxide inner layer; The surface of the chromium oxide layer 3 has at least one pit with a depth of 0.08 mm, each of which is filled with a lubricating filler 4, and the shape of the pit in the cross section of the chromium oxide layer 3 is a hexagonal prism; The lubricating filler 4 includes a polytetrafluoroethylene filler with a friction coefficient of 0.14.

[0180] The preparation method of the piston rod comprises: (1) Use alcohol to clean the substrate, then dry it at 90°C, and then perform sandblasting and activation treatment in sequence; The blasting pressure in the sandblasting roughening is 0.2MPa, the blasting distance is 50mm, the blasting angle is 73°, and the blasting material is 28-mesh aluminum oxide white corundum sand particles; The activation treatment is sandblasting to remove the oxide scale on the substrate surface and expose the new substrate surface; (2) preparing a nickel-chromium base layer 2 on the surface of the activated substrate obtained in step (1) by atmospheric plasma spraying; the process parameters of the atmospheric plasma spraying in preparing the nickel-chromium base layer 2 are: current of 350A, voltage of 50V, auxiliary gas flow rate of 8L / min, scanning speed of 160m / min, powder feeding amount of 50g / min, powder feeding carrier gas flow rate of 5.0L / min, main gas flow rate of 60L / min, spraying distance of 180mm, spraying angle of 78°, during the spraying process, the temperature of the substrate surface is 120°C, and the powder material is a nickel-chromium mixed powder with an average particle size of 80μm and a Ni mass fraction of 76wt%; (3) preparing a chromium oxide layer 3 on the surface of the nickel-chromium base layer 2 obtained in step (2) by atmospheric plasma spraying; the process parameters of the atmospheric plasma spraying in preparing the chromium oxide layer 3 are as follows: current of 550A, voltage of 50V, auxiliary gas flow rate of 5L / min, scanning speed of 140m / min, powder feeding amount of 120g / min, powder feeding carrier gas flow rate of 10L / min, main gas flow rate of 30L / min, spraying distance of 200mm, spraying angle of 85°, during the spraying process, the temperature of the substrate surface is 120°C, and the powder material is chromium trioxide powder with an average particle size of 40μm and a purity higher than 99.5wt%; (4) grinding the surface of the chromium oxide layer 3 obtained in step (3) with a 100-140 mesh coarse grinding wheel, and then polishing the ground chromium oxide layer 3 with a diamond polishing belt to obtain a polished chromium oxide layer 3 with a thickness of 0.35 mm; (5) The surface of the polished chromium oxide layer 3 obtained in step (4) is laser engraved by a laser engraving method, so that the surface of the chromium oxide layer 3 has at least one pit; the process parameters of the laser engraving are: the focal length of the spot is 14 mm, the laser pulse frequency is 30 KHZ, the pulse width is 50 ns, the laser beam scanning rate is 450 mm / s, the laser beam power is 20 W, the engraving angle is 87°, the engraving depth is 0.13 mm, the engraving shape is a mesh shape and adopts an open spiral line structure, the engraving step is 0.09 mm, and argon or CO is used. 2 Gas is used as the gas for laser engraving; (6) After preparing a polytetrafluoroethylene layer on the surface of the laser-engraved chromium oxide layer 3 obtained in step (5) by a suspension plasma spraying method, polishing is performed using 250-mesh diamond sandpaper until the surface of the chromium oxide layer 3 and the surface of the polytetrafluoroethylene layer are located in the same plane, thereby obtaining a lubricating filler 4 located in the pit on the surface of the chromium oxide layer 3, thereby obtaining the piston rod with a self-lubricating coating; The suspension plasma spraying method is as follows: polytetrafluoroethylene with an average particle size of 250 nm, 2,2,6,6-tetramethylpiperidinyl oxide and a non-ionic fluorocarbon surfactant are initially mixed by magnetic stirring, and then put into a vacuum homogenizer, the vacuum degree of the vacuum homogenizer is adjusted to -100 KPa, the mixing time is 3 minutes, and then mixed again to obtain a polytetrafluoroethylene suspension (based on the mass of the polytetrafluoroethylene suspension, the mass fraction of polytetrafluoroethylene in the polytetrafluoroethylene suspension is 96wt%, the mass fraction of the dispersant is 2wt%, and the mass fraction of the surfactant is 2wt%), and then the obtained polytetrafluoroethylene suspension is sprayed on the surface of the laser-engraved chromium oxide layer 3 by a plasma spray gun, and then the temperature is increased to 250°C at a rate of 5°C / min under one atmosphere, and then the temperature is maintained for 2h, and then cooled with the furnace to obtain a polytetrafluoroethylene layer; The process parameters for spraying the polytetrafluoroethylene suspension on the surface of the laser-engraved chromium oxide layer 3 are: current 500A, voltage 35V, auxiliary gas flow rate 2L / min, scanning speed 80m / min, powder feeding amount 35lmL / min, main gas flow rate 70L / min, spraying distance 90mm, spraying angle 90°, and the temperature of the substrate surface during spraying is 50°C.

[0181] Embodiment 6: This embodiment provides a piston rod with a self-lubricating coating, the piston rod comprising a laminated substrate 1, a nickel-chromium base layer 2 with a thickness of 0.14 mm, and a chromium oxide layer 3 with a thickness of 0.4 mm; The chromium oxide layer 3 includes a stacked chromium oxide inner layer and a chromium oxide film layer, wherein the chromium oxide inner layer is located close to the substrate 1, and the density of the chromium oxide film layer is higher than that of the chromium oxide inner layer; The surface of the chromium oxide layer 3 has at least one pit with a depth of 0.15 mm, each of which is filled with a lubricating filler 4, and the shape of the pit in the cross section of the chromium oxide layer 3 is a hexagonal prism; The lubricating filler 4 includes a polytetrafluoroethylene filler with a friction coefficient of 0.13.

[0182] The preparation method of the piston rod comprises: (1) Use alcohol to clean the substrate, then dry it at 90°C, and then perform sandblasting and activation treatment in sequence; The blasting pressure during the sandblasting roughening is 0.5MPa, the blasting distance is 50mm, the blasting angle is 72°, and the blasting material is 40-mesh aluminum oxide white corundum sand particles; The activation treatment is sandblasting to remove the oxide scale on the substrate surface and expose the new substrate surface; (2) preparing a nickel-chromium base layer 2 on the surface of the activated substrate obtained in step (1) by atmospheric plasma spraying; the process parameters of the atmospheric plasma spraying in preparing the nickel-chromium base layer 2 are: current of 500A, voltage of 50V, auxiliary gas flow rate of 3L / min, scanning speed of 160m / min, powder feeding amount of 120g / min, powder feeding carrier gas flow rate of 10.0L / min, main gas flow rate of 60L / min, spraying distance of 120mm, spraying angle of 78°, during the spraying process, the temperature of the substrate surface is 120°C, and the powder material is a nickel-chromium mixed powder with an average particle size of 80μm and a Ni mass fraction of 76wt%; (3) preparing a chromium oxide layer 3 on the surface of the nickel-chromium base layer 2 obtained in step (2) by atmospheric plasma spraying; the process parameters of the atmospheric plasma spraying in preparing the chromium oxide layer 3 are as follows: current of 350A, voltage of 60V, auxiliary gas flow rate of 5L / min, scanning speed of 130m / min, powder feeding amount of 120g / min, powder feeding carrier gas flow rate of 4L / min, main gas flow rate of 60L / min, spraying distance of 120mm, spraying angle of 75°, during the spraying process, the temperature of the substrate surface is 140°C, and the powder material is chromium trioxide powder with an average particle size of 40μm and a purity higher than 99.5wt%; (4) grinding the surface of the chromium oxide layer 3 obtained in step (3) with a 120-mesh coarse grinding wheel, and then polishing the ground chromium oxide layer 3 with a diamond polishing belt to obtain a polished chromium oxide layer 3 with a thickness of 0.45 mm; (5) The surface of the polished chromium oxide layer 3 obtained in step (4) is laser engraved by a laser engraving method, so that the surface of the chromium oxide layer 3 has at least one pit; the process parameters of the laser engraving are: the focal length of the spot is 15 mm, the laser pulse frequency is 80 KHZ, the pulse width is 100 ns, the laser beam scanning rate is 350 mm / s, the laser beam power is 18 W, the engraving angle is 90°, the engraving depth is 0.2 mm, the engraving shape is a mesh shape and adopts an open spiral line structure, the engraving step is 0.09 mm, and argon or CO is used. 2 Gas is used as the gas for laser engraving; (6) After preparing a polytetrafluoroethylene layer on the surface of the laser-engraved chromium oxide layer 3 obtained in step (5) by a suspension plasma spraying method, polishing is performed using 220-mesh diamond sandpaper until the surface of the chromium oxide layer 3 and the surface of the polytetrafluoroethylene layer are located in the same plane, thereby obtaining a lubricating filler 4 located in the pit on the surface of the chromium oxide layer 3, thereby obtaining the piston rod with a self-lubricating coating; The suspension plasma spraying method is as follows: polytetrafluoroethylene with an average particle size of 260 nm, 2,2,6,6-tetramethylpiperidinyl oxide and a non-ionic fluorocarbon surfactant are initially mixed by magnetic stirring, and then put into a vacuum homogenizer, the vacuum degree of the vacuum homogenizer is adjusted to -100 KPa, the mixing time is 2 minutes, and then mixed again to obtain a polytetrafluoroethylene suspension (based on the mass of the polytetrafluoroethylene suspension, the mass fraction of polytetrafluoroethylene in the polytetrafluoroethylene suspension is 98.5wt%, the mass fraction of the dispersant is 0.5wt%, and the mass fraction of the surfactant is 1wt%), and then the obtained polytetrafluoroethylene suspension is sprayed on the surface of the laser-engraved chromium oxide layer 3 by a plasma spray gun, and then the temperature is increased to 180°C at a rate of 1°C / min under one atmosphere, and then kept warm for 4 hours, and then cooled with the furnace to obtain a polytetrafluoroethylene layer; The process parameters for spraying the polytetrafluoroethylene suspension on the surface of the laser-engraved chromium oxide layer 3 are as follows: current 200A, voltage 60V, auxiliary gas flow rate 12L / min, scanning speed 120m / min, powder feeding amount 80lmL / min, main gas flow rate 25L / min, spraying distance 150mm, spraying angle 70~90°, and the temperature of the substrate surface during spraying is 150°C.

[0183] Embodiment 7: This embodiment provides a piston rod with a self-lubricating coating, which is the same as that of Embodiment 1 except that the nickel-chromium base layer 2 between the substrate 1 and the chromium oxide layer 3 is omitted.

[0184] Embodiment 8: This embodiment provides a piston rod with a self-lubricating coating, which is the same as that of Embodiment 1 except that the thickness of the chromium oxide layer 3 is 0.13 mm.

[0185] Embodiment 9: This embodiment provides a piston rod with a self-lubricating coating, which is the same as that of Embodiment 1 except that the thickness of the chromium oxide layer 3 is 0.7 mm.

[0186] Embodiment 10: This embodiment provides a piston rod with a self-lubricating coating, which is the same as that of Embodiment 1 except that the depth of the pits on the surface of the chromium oxide layer 3 is 0.02 mm.

[0187] Embodiment 11: This embodiment provides a piston rod with a self-lubricating coating, which is the same as that of Embodiment 1 except that the lubricating filler 4 is a chromium oxide filler with a porosity of 1%.

[0188] Embodiment 12: This embodiment provides a piston rod with a self-lubricating coating, which is the same as that of Embodiment 1 except that the lubricating filler 4 is a chromium oxide filler with a porosity of 40%.

[0189] Comparative Example 1: This comparative example provides a piston rod, which is the same as Example 1 except that the surface of the chromium oxide layer 3 does not have pits and the lubricating filler 4 filled in the pits is omitted, that is, step (5) and step (6) in the preparation method of the piston rod are omitted.

[0190] Comparative Example 2: This comparative example provides a piston rod, which is the same as Example 3 except that the surface of the chromium oxide layer 3 does not have pits and the lubricating filler 4 filled in the pits is omitted, that is, step (5) and step (6) in the preparation method of the piston rod are omitted.

[0191] Comparative Example 3: This comparative example provides a piston rod, which is the same as Example 5 except that the surface of the chromium oxide layer 3 does not have pits and the lubricating filler 4 filled in the pits is omitted, that is, step (5) and step (6) in the preparation method of the piston rod are omitted.

[0192] The wear resistance, corrosion resistance, lubrication performance and bonding strength of the piston rods provided in the above embodiments and comparative examples after 500 hours of oil immersion were tested; The wear resistance test method is: GB / T3960 sliding friction test method, and the test results are shown in Table 1 (the better the wear resistance, the higher the wear resistance coefficient); The corrosion resistance test method is: SAE J1333-1990 hydraulic cylinder piston rod corrosion test, and the test results are shown in Table 1 (the better the wear resistance, the smaller the surface tension); The lubrication performance test method is: ASTM D1894 Plastic film and sheet static and dynamic friction coefficient test method, the test results are shown in Table 1; The bonding strength test method after 500 hours of oil immersion is: HB 5476-1991 Thermal spray coating bonding strength test method, and the test results are shown in Table 1.

[0193] Table 1 From Table 1, we can get: (1) The piston rods with the self-lubricating coating provided in Examples 1 to 6 exhibit excellent wear resistance, corrosion resistance, lubrication performance and high bonding strength after being used for a period of time; (2) By comparing Example 1 with Example 7, it can be seen that the provision of the nickel-chromium base layer 2 in the present invention is conducive to enhancing the bonding performance between the metal substrate and the ceramic coating of the piston rod. This is because the thermal expansion coefficient of the nickel-chromium coating is between that of the metal substrate and the ceramic coating material, which plays a transition buffering role in the bonding between the two and reduces the peeling effect caused by stress. (3) By comparing Example 1 with Examples 8 and 9, it can be seen that when the thickness of the chromium oxide layer 3 in the present invention is 0.2-0.5 mm, the piston rod has more excellent performance. This is because the chromium oxide coating with appropriate thickness is conducive to laser engraving on the surface, avoiding the influence of the heat-affected zone of the engraving depth on the lower layer of the coating, and preventing the coating from being penetrated due to being too thin. At the same time, the appropriate thickness makes the stress of the coating moderate, which is conducive to the combination of the chromium oxide coating and the nickel-chromium base layer; (4) By comparing Example 1 with Example 10, it can be seen that when the depth of the pit on the surface of the chromium oxide layer 3 in the present invention is 0.05-0.15 mm, the piston rod has a more excellent performance. This is because the lubricating filler filled in the too shallow pit is too small, which is not conducive to the ratio of the filler surface area to the chromium oxide coating, and ultimately affects the friction and wear performance of the coating. If it is too deep, the heat-affected zone of the engraving depth may affect the coating of the lower layer of the coating, preventing the lower coating from being penetrated by the pit being too deep; (5) By comparing Example 1 with Examples 11 and 12, it can be seen that when the porosity of the lubricating filler 4 in the pits on the surface of the chromium oxide layer 3 of the present invention is 5-20%, the piston rod has more excellent performance. This is because there are appropriate pores in the filler coating, which is conducive to the infiltration of lubricating grease and increases the lubrication performance of the coating surface; (6) By comparing Example 1 with Comparative Examples 1 to 3, it can be seen that in the piston rod with a self-lubricating coating provided by the present invention, the chromium oxide film layer has a relatively high density. The dense chromium oxide film layer not only has strong corrosion resistance and wear resistance, but can also effectively block and isolate the infiltration of corrosive grease, thereby ensuring that the bonding strength between the chromium oxide layer 3 and the substrate 1 is not affected by corrosion factors; the surface of the chromium oxide layer 3 in the piston rod provided by the present invention has at least one pit, which increases the complexity of the surface of the chromium oxide layer 3, so that the contact surface has a horizontal force-bearing surface and also has a longitudinal pit, which can allow the lubricating filler 4 to be filled therein, thereby playing a good lubricating role. , thereby further improving the lubrication performance of the piston rod; in the piston rod provided by the present invention, since the chromium oxide filler with a porosity of 5-20% has open pores, it is beneficial to the storage of lubricating grease, and it is beneficial for the piston rod of the coated component to maintain the continuity of the lubricating oil film under friction and wear conditions, reduce the friction coefficient, and thus improve the lubrication performance of the piston rod; in the piston rod provided by the present invention, Mo metal filler is used as the lubricating filler 4, and the lubrication performance and corrosion resistance of the Mo metal filler can improve the defect of the non-corrosion resistance of the bonding interface between the chromium oxide layer 3 and the substrate 1; in addition, there are open gaps in the Mo metal filler, which is beneficial to the wetting of lubricating grease. The invention provides a novel lubricating oil storage system, which is beneficial for the piston rod of the coated component to maintain the continuity of the lubricating oil film under the friction and wear conditions, reduces the friction coefficient, reduces the wear rate of the piston rod, and greatly improves the service life of the piston rod; in the piston rod provided by the present invention, the polytetrafluoroethylene filler is used as the lubricating filler 4, which is beneficial for the piston rod to maintain high lubricity while improving the friction and wear resistance, and reduces the film material coefficient, thereby significantly improving the service life of the piston rod; in the present invention, the open thread surface profile is engraved by laser (that is, at least one pit is formed on the surface of the chromium oxide layer 3), thereby forming a accommodating space for the subsequent lubricating filler 4, and the complexity of the surface of the chromium oxide layer 3 is increased. At the same time, the contact surface has a horizontal force-bearing surface and a longitudinal pit, so that the lubricating filler 4 can be filled therein to play a good lubricating role; when laser engraving is performed in the present invention, the surface of the chromium oxide layer 3 with a certain depth originally containing voids forms a molten pool in a very short time due to the high-energy ablation of the laser, and after rapid cooling, the original voids in the chromium oxide layer 3 disappear, so that a dense chromium oxide film layer is formed on the surface of the chromium oxide layer 3 with a certain depth after engraving, and this dense chromium oxide film layer can effectively block and isolate the infiltration of corrosive grease, thereby ensuring that the bonding strength between the chromium oxide layer 3 and the substrate 1 is not affected by corrosion factors.

[0194] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention are within the protection scope and disclosure scope of the present invention.

Claims

1. A piston rod with a self-lubricating coating, characterized in that: The piston rod comprises a substrate and a chromium oxide layer which are stacked; The chromium oxide layer comprises a stacked chromium oxide inner layer and a chromium oxide film layer, wherein the chromium oxide inner layer is located close to the substrate, and the density of the chromium oxide film layer is higher than that of the chromium oxide inner layer; The surface of the chromium oxide layer has at least one pit, and each of the pits is filled with a lubricating filler.

2. The piston rod according to claim 1, characterized in that: A nickel-chromium base layer is also provided between the substrate and the chromium oxide layer; The thickness of the nickel-chromium base layer is 0.1-0.15 mm; The thickness of the chromium oxide layer is 0.2-0.5 mm; The depth of the pits on the surface of the chromium oxide layer is 0.05-0.15 mm.

3. The piston rod according to claim 1 or 2, characterized in that: The lubricating filler includes a chromium oxide filler having a porosity of 5 to 20%; The friction coefficient of the chromium oxide filler is 0.1-0.

25.

4. The piston rod according to claim 1 or 2, characterized in that: The lubricating filler includes Mo metal filler; The friction coefficient of the Mo metal filler is not higher than 0.

2.

5. The piston rod according to claim 1 or 2, characterized in that: The lubricating filler includes a polytetrafluoroethylene filler; The friction coefficient of the polytetrafluoroethylene filler is 0.1-0.

25.

6. A method for preparing a piston rod according to any one of claims 1 to 5, characterized in that: The preparation method comprises: A chromium oxide layer is prepared on the surface of a substrate, and the surface of the obtained chromium oxide layer is laser engraved by a laser engraving method so that the surface of the chromium oxide layer has at least one pit, and then a lubricating filler is prepared in the pit on the surface of the chromium oxide layer to obtain the piston rod.

7. The preparation method according to claim 6, characterized in that: The preparation method further comprises: pre-treating the substrate before preparing the chromium oxide layer; The preparation method further comprises: between the pre-treatment and the preparation of the chromium oxide layer, preparing a nickel-chromium base layer, wherein the method for preparing the nickel-chromium base layer comprises atmospheric plasma spraying; The preparation of the chromium oxide layer and the laser engraving also include grinding and surface polishing in sequence; The thickness of the polished chromium oxide layer obtained after the surface polishing is 0.3-0.5 mm; The process parameters of the laser engraving are: the focal length of the spot is 10~15mm, the laser pulse frequency is 10~100KHz, the pulse width is 10~150ns, the laser beam scanning rate is 300~500mm / s, the laser beam power is 15~25w, the engraving angle is 85~90°, the engraving depth is 0.05~0.20mm, the engraving shape is a mesh shape and adopts an open spiral line structure, the engraving step is 0.08~0.12mm, and argon gas or CO2 gas is selected as the gas for laser engraving.

8. The preparation method according to claim 6, characterized in that: The method for preparing the lubricating filler comprises: depositing a chromium oxide-polyester composite coating on the surface of the laser-engraved chromium oxide layer, and then grinding it until the surface of the chromium oxide layer and the surface of the chromium oxide-polyester composite coating are located in the same plane, and then removing the polyester by heat treatment to obtain the lubricating filler located in the pit on the surface of the chromium oxide layer.

9. The preparation method according to claim 6, characterized in that: The method for preparing the lubricating filler comprises: preparing a Mo metal layer on the surface of the laser-engraved chromium oxide layer and then grinding it until the surface of the chromium oxide layer and the surface of the Mo metal layer are in the same plane, thereby obtaining a lubricating filler in the pit on the surface of the chromium oxide layer.

10. The preparation method according to claim 6, characterized in that: The method for preparing the lubricating filler comprises: preparing a polytetrafluoroethylene layer on the surface of the laser-engraved chromium oxide layer by a suspension plasma spraying method and then polishing the layer until the surface of the chromium oxide layer and the surface of the polytetrafluoroethylene layer are located in the same plane, thereby obtaining a lubricating filler located in a pit on the surface of the chromium oxide layer.

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