Preparation method of surface lubricating self-adaptive composite material

Abstract

The invention belongs to the technical field of lubricating materials, and particularly relates to a preparation method of a surface lubricating self-adaptive composite material. The invention provides a preparation method of a surface lubrication self-adaptive composite material, which comprises the following steps: firstly, preparing photocuring 3D printing ink with different friction behavior characteristics, secondly, designing a gradient lubrication surface (patterning), and then, carrying out 3D printing forming by adopting the prepared photocuring 3D printing ink according to the designed gradient lubrication surface, so as to obtain the surface lubrication self-adaptive composite material. And finally, a formed lubricating device is subjected to light curing treatment and heat treatment to obtain the gradient self-lubricating polyimide surface, and gradient, self-adaptability and lubricating behavior customization of the lubricating surface and the device are achieved. The surface lubrication self-adaptive composite surface and the device provided by the invention have low friction coefficient and excellent tribological controllability at the same time.

Description

Technical Field

[0001] This invention belongs to the field of lubrication materials technology, specifically relating to a method for preparing a surface lubrication adaptive composite material. Background Technology

[0002] In the field of solid lubrication, polymers and their composites have become ideal friction pair materials in many machines due to their good self-lubricating properties, light weight, insulation, and vibration absorption. Against the backdrop of lightweight and integrated design of precision components in various fields, the application of many polymer lubricating materials, including polyimide, polyetheretherketone, epoxy resin, polyphenylene sulfide, polyurethane, and silicone rubber, continues to expand in solving sealing, lubrication, and wear-resistant problems under harsh operating conditions such as high and low temperatures, complex environments, and media. However, the rapid development of space exploration and the revitalization of manufacturing have created an extremely urgent demand for intelligent lubrication and manufacturing.

[0003] Existing lubricating composite materials generally have a single, homogeneous composition and specific frictional properties, making it difficult to adjust their frictional properties according to the operating environment. In order to achieve environmental adaptability of lubricating composite materials, researchers have begun to study lubricating materials with surface lubrication self-adaptive properties. Summary of the Invention

[0004] In view of this, the present invention provides a method for preparing a surface lubrication adaptive composite material. The surface lubrication adaptive composite material prepared according to the preparation method provided by the present invention has controllable friction properties and can meet the service requirements of lubrication materials in different fields.

[0005] To address the aforementioned technical problems, this invention provides a method for preparing a surface lubrication adaptive composite material, comprising the following steps:

[0006] Photopolymerizable 3D printing inks with different tribological properties are provided; the photopolymerizable 3D printing inks include photosensitive polyimide oligomers and additives;

[0007] Patterned 3D printing is performed using the aforementioned photocurable 3D printing ink to obtain a patterned blank.

[0008] The patterned preform is subjected to photocuring and heat treatment in sequence to obtain the surface lubrication adaptive composite material.

[0009] Preferably, the printing equipment used for patterned 3D printing includes a forming platform 1, a laser light source 2, a material tank 3, and slicing printing control software 4;

[0010] The material pool 3 includes a plurality of material troughs, the number of which is 1 to 10.

[0011] Preferably, the conditions for patterned 3D printing include: a light source power of 250–7000 mW / cm². 2 The slice thickness is 30–75 μm, the exposure time is 23–27 s for the first layer and 10–15 s for the other layers.

[0012] Preferably, the photosensitive polyimide oligomer has the structure shown in Formula 1:

[0013]

[0014] Wherein, 1≤X≤25, 0≤Y≤25; R1 is thionyl; R2 is carbonyl or hexafluoroisopropylidene; R3 is 1,4-p-diphenoxy; R4 is hydrogen or methyl.

[0015] Preferably, the additive includes one or more of solid lubricating additives, diluents, crosslinking agents, wetting agents, defoamers, and photoinitiators;

[0016] The mass ratio of the photosensitive polyimide oligomer to the solid lubricant additive is 40-70:1-15;

[0017] The mass ratio of the photosensitive polyimide oligomer to the diluent is 40-70:20-40;

[0018] The mass ratio of the photosensitive polyimide oligomer to the crosslinking agent is 40-70:5-10;

[0019] The mass ratio of the photosensitive polyimide oligomer to the wetting agent is 40–70:0.5–3;

[0020] The mass ratio of the photosensitive polyimide oligomer to the defoamer is 40–70:0.5–2;

[0021] The mass ratio of the photosensitive polyimide oligomer to the photoinitiator is 40–70:0.5–2.

[0022] Preferably, the solid lubricant additive includes one or more of the following: polytetrafluoroethylene micro powder, molybdenum disulfide nanosheets, silica micro powder, fluorinated graphene, graphitic carbon nitride, spherical graphite, and graphene oxide.

[0023] The diluent includes one or more of N-vinylpyrrolidone, N,N-dimethylacrylamide, N-vinylformamide, and acrylmorpholine;

[0024] The crosslinking agent includes one or more of propane trimethylol acrylate, trimethylolpropane trimethacrylate, and epoxy acrylate;

[0025] The wetting agent includes one or more of ANTI-TERRA-U wetting agent, BYK-165 wetting agent, and BYK-ET 3001 wetting agent;

[0026] The defoamer includes one or more of BYK-021 defoamer, BYK-023 defoamer, BYK-044 defoamer, and BYK-037 defoamer;

[0027] The photoinitiator includes one or more of photoinitiator 819, photoinitiator TPO, photoinitiator TPO-L, and photoinitiator LAP.

[0028] Preferably, the conditions for photocuring include: the light source is ultraviolet light, the light source power is 1 to 500W, and the light exposure time is 2 seconds to 2 hours.

[0029] Preferably, the heat treatment includes the following steps: heating to a first temperature at a first heating rate and holding for a first time; heating from the first temperature to a second temperature at a second heating rate and holding for a second time; heating from the second temperature to a third temperature at a third heating rate and holding for a third time; heating from the third temperature to a fourth temperature at a fourth heating rate and holding for a fourth time; heating from the fourth temperature to a fifth temperature at a fifth heating rate and holding for a fifth time; and heating from the fifth temperature to a sixth temperature at a sixth heating rate and holding for a sixth time.

[0030] Preferably, the first temperature is 50–80°C, and the first heat preservation time is 3–5 hours; the second temperature is 110–130°C, and the second heat preservation time is 1–3 hours; the third temperature is 150–170°C, and the third heat preservation time is 1–3 hours; the fourth temperature is 190–210°C, and the fourth heat preservation time is 0.5–1.5 hours; the fifth temperature is 240–260°C, and the fifth heat preservation time is 0.5–1.5 hours; the sixth temperature is 290–310°C, and the sixth heat preservation time is 1–3 hours.

[0031] The first heating rate, the second heating rate, the third heating rate, the fourth heating rate, the fifth heating rate, and the sixth heating rate are all independently 1 to 5 °C / min.

[0032] Preferably, the patterned blank includes a striped blank or a honeycomb blank;

[0033] The coefficient of friction of the surface lubrication adaptive composite material is 0.05 to 0.5.

[0034] This invention provides a method for preparing a surface-lubricating adaptive composite material, comprising the following steps: providing photocurable 3D printing inks with different tribological properties; the photocurable 3D printing inks include photosensitive polyimide oligomers and additives; using the photocurable 3D printing inks for patterned 3D printing to obtain a patterned preform; and sequentially subjecting the patterned preform to photocuring and heat treatment to obtain the surface-lubricating adaptive composite material. This invention utilizes 3D printing for integrated rapid prototyping of polyimide self-lubricating composite surfaces or devices that achieve adaptive frictional behavior through patterned lubricating surfaces; through the patterning of the lubricating surface and the design of the material structure, lubricating surfaces with precisely controllable, gradient, and adaptive lubricating performance can be obtained to meet the service requirements of different fields. The surface-lubricating adaptive composite material provided by this invention has a low coefficient of friction while possessing excellent tribological controllability. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the printing equipment used in an embodiment of the present invention, wherein 1 is the forming platform, 2 is the laser light source, 3 is the material tank, and 4 is the slicing printing control software;

[0036] Figure 2 This is a schematic diagram of the model structure of Example 1;

[0037] Figure 3 Here is a photograph of the sample obtained in Example 1;

[0038] Figure 4 The friction curve of the surface lubrication adaptive composite material prepared in Example 1;

[0039] Figure 5 This is a schematic diagram of the model structure in Example 2;

[0040] Figure 6 Here is a photograph of the sample obtained in Example 2;

[0041] Figure 7 The friction curve of the surface lubrication adaptive composite material prepared in Example 2;

[0042] Figure 8 This is a schematic diagram of the model structure in Example 3;

[0043] Figure 9 Here is a photograph of the sample obtained in Example 3;

[0044] Figure 10 The friction curve of the surface lubrication adaptive composite material prepared in Example 3;

[0045] Figure 11 This is a schematic diagram of the model structure in Example 4;

[0046] Figure 12 Here is a photograph of the sample obtained in Example 4;

[0047] Figure 13 The friction curves are for the surface lubrication adaptive composite material prepared in Example 4. Detailed Implementation

[0048] This invention provides a method for preparing a surface lubrication adaptive composite material, comprising the following steps:

[0049] Photopolymerizable 3D printing inks with different tribological properties are provided; the photopolymerizable 3D printing inks include photosensitive polyimide oligomers and additives;

[0050] Patterned 3D printing is performed using the aforementioned photocurable 3D printing ink to obtain a patterned blank.

[0051] The patterned preform is subjected to photocuring and heat treatment in sequence to obtain the surface lubrication adaptive composite material.

[0052] This invention provides photocurable 3D printing inks with different tribological properties. In this invention, the photocurable 3D printing ink comprises a photosensitive polyimide oligomer and additives; the photosensitive polyimide oligomer (PI) may have the structure shown in Formula 1:

[0053]

[0054] Wherein, 1≤X≤25, X can be specifically 5; 0≤Y≤25, Y can be specifically 5; R1 can be thionyl; R2 can be carbonyl or hexafluoroisopropylidene; R3 can be 1,4-p-diphenoxy; R4 can be hydrogen or methyl.

[0055] As a specific embodiment of the present invention, the photosensitive polyimide oligomer can be a substance having the structure shown in Formula 2:

[0056]

[0057] In one specific embodiment of the present invention, the number average molecular weight of the photosensitive polyimide oligomer can be 8000-20000 g / mol, or 10000-15000 g / mol.

[0058] In one specific embodiment of the present invention, the additive may include one or more of solid lubricating additives, diluents, crosslinking agents, wetting agents, defoamers, and photoinitiators, specifically a mixture of diluents, crosslinking agents, wetting agents, defoamers, and photoinitiators, or a mixture of solid lubricating additives, diluents, crosslinking agents, wetting agents, defoamers, and photoinitiators. In another specific embodiment of the present invention, the solid lubricating additive may include one or more of polytetrafluoroethylene (PTFFE) micropowder, molybdenum disulfide nanosheets, silica micropowder, fluorinated graphene, graphitic carbon nitride, spherical graphite, and graphene oxide, specifically polytetrafluoroethylene (PTFFE) micropowder, molybdenum disulfide nanosheets, silica micropowder, fluorinated graphene, graphitic carbon nitride, spherical graphite, or graphene oxide; the polytetrafluoroethylene micropowder includes nano-sized polytetrafluoroethylene micropowder and / or micron-sized polytetrafluoroethylene micropowder, wherein the average particle size of the nano-sized polytetrafluoroethylene micropowder is 200–500 nm, and the micron-sized... The polytetrafluoroethylene (PTFE) micropowder has an average particle size of 5–30 μm; the molybdenum disulfide (MoD) nanosheets include nanoscale MoD nanosheets and / or MoD nanosheets with an average particle size of 200–500 nm, and the micrometer-scale MoD nanosheets have an average particle size of 0.5–2 μm; the silica micropowder has an average particle size of 20–2000 nm; the fluorinated graphene has an average particle size of 4–10 μm; the graphitic carbon nitride has an average particle size of 1–10 μm; the spherical graphite has an average particle size of 8–20 μm; and the graphene oxide has an average particle size of 100–100,000 nm. This invention allows for the selection of 1–5 specific solid lubricant additives in the surface lubrication adaptive composite material.

[0059] As a specific embodiment of the present invention, the diluent may include one or more of N-vinylpyrrolidone, N,N-dimethylacrylamide, N-vinylformamide and acrylmorpholine, and may specifically be N-vinylpyrrolidone.

[0060] In one specific embodiment of the present invention, the crosslinking agent may include one or more of propane trimethylol acrylate, trimethylolpropane trimethacrylate, and epoxy acrylate, and may specifically be propane trimethylol acrylate.

[0061] As a specific embodiment of the present invention, the wetting agent may include one or more of ANTI-TERRA-U wetting agent, BYK-165 wetting agent and BYK-ET 3001 wetting agent, and may specifically be ANTI-TERRA-U wetting agent.

[0062] As a specific embodiment of the present invention, the defoamer may include one or more of BYK-021 defoamer, BYK-023 defoamer, BYK-044 defoamer and BYK-037 defoamer, and may specifically be BYK-021 defoamer.

[0063] As a specific embodiment of the present invention, the photoinitiator may include one or more of photoinitiator 819, photoinitiator TPO, photoinitiator TPO-L and photoinitiator LAP, and may specifically be photoinitiator 819.

[0064] In one specific embodiment of the present invention, the mass ratio of the photosensitive polyimide oligomer to the solid lubricant additive can be 40-70:1-15, specifically 60:1, 50:7, 45:10, or 50:8; the mass ratio of the photosensitive polyimide oligomer to the diluent can be 40-70:20-40, specifically 55:30, 60:25, 50:33, 45:30, or 50:25; the mass ratio of the photosensitive polyimide oligomer to the crosslinking agent can be 40-70:5-10, specifically 55:10, 60:5, 50:8, or 45:15. The mass ratio of the photosensitive polyimide oligomer to the wetting agent can be 40-70:0.5-3, specifically 55:2, 60:2, 50:3, 45:3, or 50:3; the mass ratio of the photosensitive polyimide oligomer to the defoamer can be 40-70:0.5-2, specifically 55:2, 60:2, 50:2, 45:1, or 50:1; the mass ratio of the photosensitive polyimide oligomer to the photoinitiator can be 40-70:0.5-2, specifically 55:1, 60:2, 50:2, 45:2, or 50:2.

[0065] In this invention, the specific types and amounts of solid lubricant additives, diluents, crosslinking agents, wetting agents, defoamers, and photoinitiators can be designed according to the friction coefficient required by the surface lubrication adaptive composite material (photocurable 3D printing ink with different tribological properties).

[0066] This invention provides a method for preparing photocurable 3D printing inks with different tribological properties: photosensitive polyimide oligomers and additives are mixed to obtain photocurable 3D printing inks with different tribological properties. As a specific embodiment of this invention, the mixing method may include mechanical stirring, ball milling, or ultrasonic dispersion. This invention does not impose special limitations on the mixing conditions, as long as uniform mixing is achieved.

[0067] As a specific embodiment of the present invention, the viscosity of the photocurable 3D printing ink with different tribological properties can be less than 20,000 cps, or it can be 10,000 to 15,000 cps.

[0068] As a specific embodiment of the present invention, the number of photocurable 3D printing inks with different tribological properties may include 2 to 5 types of photocurable 3D printing inks.

[0069] This invention utilizes the aforementioned photocurable 3D printing ink for patterned 3D printing to obtain a patterned blank. In one specific embodiment of this invention, the printing equipment used for patterned 3D printing includes a forming platform 1, a laser light source 2, a material tank 3, and slicing printing control software 4. In another specific embodiment, the forming platform adopts a detachable design, is made of aluminum alloy, and its movement is a vertical servo motion. The laser light source can emit ultraviolet light with a wavelength of 405nm. The material tank can be disc-shaped, and the material tank 3 includes several material slots, the number of which can be 1 to 10. This invention can fill different material slots with photocurable 3D printing inks with different tribological properties. During the printing process, it can rotate according to the instructions issued by the software to use different photocurable 3D printing inks for printing. The slicing control software functions to: plan the layer thickness for slicing the model and control the patterning material of a single layer; for patterning of multiple photocurable 3D printing inks, it comprehensively controls and displaces the Z-axis platform and material tank by issuing instructions, and performs patterned exposure of the light source. Figure 1 This is a schematic diagram of the printing equipment used in an embodiment of the present invention, wherein 1 is the forming platform, 2 is the laser light source, 3 is the material tank, and 4 is the slicing printing control software.

[0070] As a specific embodiment of the present invention, the conditions for patterned 3D printing may include: a light source power of 250–7000 mW / cm². 2 The slice thickness is 30–75 μm, with one or more layers. The exposure time is 23–27 s for the first layer and 10–15 s for the other layers. A light source power of 500–5000 mW / cm² is also acceptable. 2 The slice thickness is 50-65 μm, the number of slices is 3-5, the exposure time is 25s for the first slice and 10-15s for the other slices.

[0071] In one specific embodiment of the present invention, after patterned 3D printing, the process may further include: sequentially washing and drying the patterned 3D printed product to obtain the patterned preform; the washing agent includes a mixture of ethanol and dimethylformamide, wherein the volume ratio of ethanol to dimethylformamide can be 1:1; the washing can be performed under ultrasonic conditions; the present invention does not have any particular limitation on the ultrasonic conditions, and conventional methods in the art can be used. The present invention does not have any particular limitation on the drying, as long as the solvent on the material surface can be removed.

[0072] In one specific embodiment of the present invention, the patterned blank may include a striped blank or a honeycomb blank; the width of each stripe in the striped blank may be independently 100μm to 2mm; the pore size of each honeycomb in the honeycomb blank may be independently 500μm to 3mm.

[0073] This invention allows for the design of lubrication surface patterns using the simulation optimization software Python, based on the friction coefficient of the desired material (surface lubrication adaptive composite material).

[0074] In this invention, the principle of forming a patterned blank using a printing device is as follows: First, a model is designed, its surface is patterned, and the materials and printing parameters used for patterning are specified. Then, the software is used for slicing, planning, and setting curing parameters. For multi-material stripe patterning in the Z-axis direction, only the printing ink of each layer is changed during printing. Through accumulation and superposition, a multi-material patterned surface with different stripe widths is formed. For multi-material patterning in the XY direction, the path planning of the software is mainly used. First, a pattern of one material is formed. Without changing the Z-axis positioning, another one or more materials are patterned, thereby realizing multi-material patterned printing in the XY direction. Finally, through the accumulation and superposition of multiple layers, the final multi-material patterned printed part is formed.

[0075] After obtaining the patterned preform, the present invention sequentially performs photocuring and heat treatment on the patterned preform to obtain the surface lubrication adaptive composite material. As a specific embodiment of the present invention, the photocuring conditions may include: the light source is ultraviolet light, the light source power is 1-500W, and the illumination time is 2s-2h; alternatively, the light source may be ultraviolet light, the light source power is 100-300W, and the illumination time is 5s-1h.

[0076] In one specific embodiment of the present invention, the heat treatment may include the following process: heating to a first temperature at a first heating rate and holding for a first time; heating from the first temperature to a second temperature at a second heating rate and holding for a second time; heating from the second temperature to a third temperature at a third heating rate and holding for a third time; heating from the third temperature to a fourth temperature at a fourth heating rate and holding for a fourth time; heating from the fourth temperature to a fifth temperature at a fifth heating rate and holding for a fifth time; and heating from the fifth temperature to a sixth temperature at a sixth heating rate and holding for a sixth time. In another specific embodiment of the present invention, the first temperature may be 50–80°C, or 60–70°C; the first holding time may be 3–5 hours, specifically 4 hours; the second temperature may be 110–130°C, or 120–125°C; the second holding time may be 1–3 hours, specifically 2 hours; the third temperature may be 150–170°C, or 160–170°C; and the third holding time may be 1–3 hours, specifically 2 hours. The fourth temperature can be 190–210℃, or 200–205℃; the fourth holding time can be 0.5–1.5 h, specifically 1 h; the fifth temperature can be 240–260℃, or 250–255℃; the fifth holding time can be 0.5–1.5 h, specifically 1 h; the sixth temperature can be 290–310℃, or 300–305℃; the sixth holding time can be 1–3 h, specifically 2 h. As a specific embodiment of the present invention, the first heating rate, second heating rate, third heating rate, fourth heating rate, fifth heating rate, and sixth heating rate can be independently 1–5℃ / min, or independently 2–4℃ / min. As a specific embodiment of the present invention, the heat treatment can be carried out under a protective atmosphere or vacuum conditions, the protective atmosphere being nitrogen and / or argon, specifically nitrogen or argon.

[0077] In one specific embodiment of the present invention, the heat treatment may further include: cooling the heat-treated product to room temperature; the room temperature may be 20–35°C, or 25–30°C. The present invention does not specifically limit the cooling method.

[0078] In one specific embodiment of the present invention, the friction coefficient of the surface lubrication adaptive composite material can be 0.05 to 0.5; the friction coefficient of the striped patterned surface lubrication adaptive composite material is 0.05 to 0.2, and the friction coefficient of the honeycomb striped patterned surface lubrication adaptive composite material is 0.09 to 0.5.

[0079] As a specific embodiment of the present invention, the surface lubrication adaptive composite material has a mechanical strength greater than 70 MPa, a molding accuracy better than 50 μm, and a dimensional shrinkage rate of less than 3%.

[0080] This invention enables the integrated rapid manufacturing of polyimide lubricating surfaces and devices with functions such as gradient, self-regulation of friction behavior, and adaptive properties; the coefficient of friction in the unidirectional lubrication direction can vary from 0.05 to 0.5, and the unidirectional components of the composite lubricating surface are gradient-based, composed of different solid lubricating additives dispersed in the surface.

[0081] This invention designs a gradient patterned lubricating composite surface for photopolymer 3D printing of polyimide self-lubricating composite materials. It uses photopolymer 3D printing based on the designed gradient multi-material lubricating surface and device model to achieve integrated rapid prototyping of polyimide self-lubricating composite surfaces and devices with adaptive friction behavior characteristics through gradient patterned lubricating surfaces.

[0082] The surface lubrication adaptive composite material prepared according to the preparation method provided by the present invention can be used in the fields of aerospace, automotive manufacturing, microelectronics, nuclear energy or advanced manufacturing.

[0083] This invention enables the gradient molding and manufacturing of polyimide self-lubricating composite patterned surfaces, achieving integrated manufacturing of gradient lubricating surfaces with precisely controlled friction coefficients of 0.05 to 0.5. The resulting composite material possesses the self-adaptability and gradient lubrication properties of polyimide self-lubricating surfaces, realizing the integrated manufacturing of customizable, irregularly shaped, thin-walled, and other complex polyimide lubricating structures and their lubricating surfaces to meet the demanding friction environment requirements in key fields such as aerospace, nuclear energy, and advanced manufacturing.

[0084] To further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0085] The 3D printing equipment used in this embodiment is Figure 1 The printing device shown has the following structure.

[0086] Examples 1-4

[0087] The following types of photocurable 3D printing inks were used to prepare surface lubrication adaptive composite surfaces and devices. The specific types of solid lubricant additives in the printing inks and the quantities of printing inks are shown in Table 1.

[0088] 55 parts of photosensitive polyimide oligomer with the structure shown in Formula 2 (number average molecular weight of about 8000 g / mol), 30 parts of diluent N-vinylpyrrolidone, 10 parts of crosslinking agent propane trimethylol ester, 2 parts of ANTI-TERRA-U wetting agent, 2 parts of BYK-021 defoamer and 1 part of photoinitiator 819 were added to a ball milling jar and ball milled at 3000 r / min for 10 min to obtain the first photocurable 3D printing ink;

[0089] 60 parts of photosensitive polyimide oligomer with the structure shown in Formula 2 (number average molecular weight of about 8000 g / mol), 10 parts of solid lubricant additive (polytetrafluoroethylene with an average particle size of 500 nm), 25 parts of diluent N-vinylpyrrolidone, 5 parts of crosslinking agent propane trimethylol ester, 2 parts of ANTI-TERRA-U wetting agent, 2 parts of BYK-021 defoamer and 2 parts of photoinitiator 819 were added to a ball mill jar and ball milled at a speed of 3000 r / min for 10 min to obtain the second photocurable 3D printing ink.

[0090] 50 parts of photosensitive polyimide oligomer with the structure shown in Formula 2 (number average molecular weight of about 8000 g / mol), 7 parts of solid lubricant additive (graphene oxide with an average particle size of 200 nm), 33 parts of diluent N-vinylpyrrolidone, 8 parts of crosslinking agent propane trimethylol ester, 3 parts of ANTI-TERRA-U wetting agent, 2 parts of BYK-021 defoamer and 2 parts of photoinitiator 819 were added to a ball mill jar and ball milled at 3000 r / min for 10 min to obtain the third photocurable 3D printing ink.

[0091] 50 parts of photosensitive polyimide oligomer with the structure shown in Formula 2 (number average molecular weight of about 8000 g / mol), 7 parts of solid lubricant additive (fluorinated graphene with an average particle size of 5 μm), 33 parts of diluent N-vinylpyrrolidone, 8 parts of crosslinking agent propane trimethylol ester, 3 parts of ANTI-TERRA-U wetting agent, 2 parts of BYK-021 defoamer and 2 parts of photoinitiator 819 were added to a ball mill jar and ball milled at 3000 r / min for 10 min to obtain the fourth photocurable 3D printing ink.

[0092] 50 parts of photosensitive polyimide oligomer with the structure shown in Formula 2 (number average molecular weight of about 8000 g / mol), 8 parts of solid lubricant additive (spherical graphite with an average particle size of 10 μm), 25 parts of diluent N-vinylpyrrolidone, 12 parts of crosslinking agent propane trimethylol ester, 3 parts of ANTI-TERRA-U wetting agent, 1 part of BYK-021 defoamer and 2 parts of photoinitiator 819 were added to a ball mill jar and ball milled at 3000 r / min for 10 min to obtain the fifth photocurable 3D printing ink.

[0093] 45 parts of photosensitive polyimide oligomer with the structure shown in Formula 2 (number average molecular weight of about 8000 g / mol), 10 parts of solid lubricant additive (lamellar molybdenum disulfide with an average particle size of 500 nm), 30 parts of diluent N-vinylpyrrolidone, 10 parts of crosslinking agent propane trimethylol ester, 3 parts of ANTI-TERRA-U wetting agent, 1 part of BYK-021 defoamer and 2 parts of photoinitiator 819 were added to a ball mill jar and ball milled at 3000 r / min for 10 min to obtain the sixth photocurable 3D printing ink.

[0094] 50 parts of photosensitive polyimide oligomer with the structure shown in Formula 2 (number average molecular weight of about 8000 g / mol), 8 parts of solid lubricant additive (carbon nitride with an average particle size of 100 nm), 25 parts of diluent N-vinylpyrrolidone, 10 parts of crosslinking agent propane trimethylol ester, 3 parts of ANTI-TERRA-U wetting agent, 1 part of BYK-021 defoamer and 2 parts of photoinitiator 819 were added to a ball mill jar and ball milled at 3000 r / min for 10 min to obtain the seventh photocurable 3D printing ink.

[0095] Photopolymer 3D printing inks with different tribological properties were filled into the material tank and 3D printing was carried out in stripe pattern (stripe width is 100μm to 3mm). The printing parameters were: wavelength of light source is 405nm, light source intensity is 5000mW / cm2, single layer slice thickness is 50μm, first layer exposure time is 25s, and exposure time of other layers is 15s.

[0096] After printing, the printed parts were removed and ultrasonically cleaned using a 1:1 volume ratio mixture of ethanol and dimethylformamide, followed by drying. The dried product was then subjected to photocuring and heat treatment to obtain a surface-lubricated adaptive composite material. The photocuring conditions were: ultraviolet light source, light source power of 200W, and light exposure time of 0.5h. The heat treatment process involved heating to 80℃ at a rate of 2℃ / min and holding for 4h, then heating to 120℃ at a rate of 2℃ / min and holding for 2h, then heating to 160℃ at a rate of 2℃ / min and holding for 2h, then heating to 200℃ at a rate of 2℃ / min and holding for 1h, then heating to 250℃ at a rate of 2℃ / min and holding for 1h, and finally heating to 300℃ at a rate of 2℃ / min and holding for 2h. The product was then allowed to cool naturally to room temperature (25℃).

[0097] Table 1. Conditions for preparing surface lubrication adaptive composite materials in Examples 1-4

[0098]

[0099]

[0100] Figure 2 This is a schematic diagram of the model structure in Example 1. Figure 3 Here is a photograph of the sample obtained in Example 1; Figure 4 The friction curve of the surface lubrication adaptive composite material prepared in Example 1; Figure 5 This is a schematic diagram of the model structure in Example 2. Figure 6 This is a photograph of the sample obtained in Example 2. Figure 7 The friction curve of the surface lubrication adaptive composite material prepared in Example 2; Figure 8 This is a schematic diagram of the model structure in Example 3. Figure 9 This is a photograph of the sample obtained in Example 3. Figure 10 The friction curve of the surface lubrication adaptive composite material prepared in Example 3; Figure 11 This is a schematic diagram of the model structure in Example 4. Figure 12 This is a photograph of the sample obtained in Example 4. Figure 13 The figure shows the friction curve of the surface lubrication adaptive composite material prepared in Example 4; pure PI in the figure refers to the material formed by printing ink without solid lubricant additives.

[0101] The tribological properties of the surface lubrication adaptive composite materials prepared in Examples 1-4 were tested under the conditions of a load of 10 N, a frequency of 0.1 Hz, and a pair of GCr15 steel balls. The results are listed in Table 2.

[0102] Table 2. Friction coefficients of the surface lubrication adaptive composite materials prepared in Examples 1-4

[0103] Example Surface friction coefficient of the design Actual friction coefficient of the sample Example 1 0.23 0.25 Example 2 0.45 0.42 Example 3 0.06 0.06 Example 4 0.08 0.07

[0104] Summary Tables 1-2 and Figures 2-13 It can be seen that by controlling the types of solid lubricant additives, 3D printing inks with different frictional properties can be obtained. Through patterning, surface lubrication adaptive composite materials with the required friction coefficient can be prepared. The preparation method provided by this invention can realize the application of polyimide self-lubricating composite materials, surfaces, and devices in personalized, customized, gradient lubrication, and adaptive lubrication performance requirements. It can solve the problem of arbitrary control and adaptive matching of the lubrication behavior of polyimide self-lubricating composite materials, thereby meeting the friction and wear service requirements under harsh working conditions.

[0105] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for preparing a surface lubrication adaptive composite material, characterized in that, Includes the following steps: Photopolymerizable 3D printing inks with different tribological properties are provided; the photopolymerizable 3D printing inks include photosensitive polyimide oligomers and additives; Patterned 3D printing is performed using the aforementioned photocurable 3D printing ink to obtain a patterned blank. The patterned preform is subjected to photocuring and heat treatment in sequence to obtain the surface lubrication adaptive composite material.

2. The method for preparing the surface lubrication adaptive composite material according to claim 1, characterized in that, The printing equipment used for patterned 3D printing includes a forming platform (1), a laser light source (2), a material tank (3), and slicing printing control software (4); The material pool (3) includes several material troughs, the number of which is 1 to 10.

3. The method for preparing the surface lubrication adaptive composite material according to claim 1 or 2, characterized in that, Conditions for patterned 3D printing include: light source power of 250–7000 mW / cm². 2 The slice thickness is 30–75 μm, the exposure time is 23–27 s for the first layer and 10–15 s for the other layers.

4. The method for preparing the surface lubrication adaptive composite material according to claim 1, characterized in that, The photosensitive polyimide oligomer has the structure shown in Formula 1: Wherein, 1≤X≤25, 0≤Y≤25; R1 is thionyl; R2 is carbonyl or hexafluoroisopropylidene; R3 is 1,4-p-diphenoxy; R4 is hydrogen or methyl.

5. The method for preparing the surface lubrication adaptive composite material according to claim 1 or 4, characterized in that, The additives include one or more of solid lubricating additives, diluents, crosslinking agents, wetting agents, defoamers, and photoinitiators; The mass ratio of the photosensitive polyimide oligomer to the solid lubricant additive is 40-70:1-15; The mass ratio of the photosensitive polyimide oligomer to the diluent is 40-70:20-40; The mass ratio of the photosensitive polyimide oligomer to the crosslinking agent is 40-70:5-10; The mass ratio of the photosensitive polyimide oligomer to the wetting agent is 40–70:0.5–3; The mass ratio of the photosensitive polyimide oligomer to the defoamer is 40–70:0.5–2; The mass ratio of the photosensitive polyimide oligomer to the photoinitiator is 40–70:0.5–2.

6. The method for preparing the surface lubrication adaptive composite material according to claim 5, characterized in that, The solid lubricant additive includes one or more of the following: polytetrafluoroethylene micro powder, molybdenum disulfide nanosheets, silica micro powder, fluorinated graphene, graphitic carbon nitride, spherical graphite, and graphene oxide. The diluent includes one or more of N-vinylpyrrolidone, N,N-dimethylacrylamide, N-vinylformamide, and acrylmorpholine; The crosslinking agent includes one or more of propane trimethylol acrylate, trimethylolpropane trimethacrylate, and epoxy acrylate; The wetting agent includes one or more of ANTI-TERRA-U wetting agent, BYK-165 wetting agent, and BYK-ET 3001 wetting agent; The defoamer includes one or more of BYK-021 defoamer, BYK-023 defoamer, BYK-044 defoamer, and BYK-037 defoamer; The photoinitiator includes one or more of photoinitiator 819, photoinitiator TPO, photoinitiator TPO-L, and photoinitiator LAP.

7. The method for preparing the surface lubrication adaptive composite material according to claim 1, characterized in that, The conditions for photocuring include: the light source is ultraviolet light, the light source power is 1 to 500W, and the light exposure time is 2 seconds to 2 hours.

8. The method for preparing the surface lubrication adaptive composite material according to claim 1, characterized in that, The heat treatment includes the following steps: heating to a first temperature at a first heating rate and holding for a first time; heating from the first temperature to a second temperature at a second heating rate and holding for a second time; The temperature is increased from the second temperature to the third temperature at a third heating rate and then held for a third time; the temperature is increased from the third temperature to the fourth temperature at a fourth heating rate and then held for a fourth time; the temperature is increased from the fourth temperature to the fifth temperature at a fifth heating rate and then held for a fifth time; the temperature is increased from the fifth temperature to the sixth temperature at a sixth heating rate and then held for a sixth time.

9. The method for preparing the surface lubrication adaptive composite material according to claim 8, characterized in that, The first temperature is 50–80℃, and the first heat preservation time is 3–5 hours; the second temperature is 110–130℃, and the second heat preservation time is 1–3 hours; the third temperature is 150–170℃, and the third heat preservation time is 1–3 hours; the fourth temperature is 190–210℃, and the fourth heat preservation time is 0.5–1.5 hours; the fifth temperature is 240–260℃, and the fifth heat preservation time is 0.5–1.5 hours; the sixth temperature is 290–310℃, and the sixth heat preservation time is 1–3 hours. The first heating rate, the second heating rate, the third heating rate, the fourth heating rate, the fifth heating rate, and the sixth heating rate are all independently 1 to 5 °C / min.

10. The method for preparing the surface lubrication adaptive composite material according to claim 1 or 2, characterized in that, The patterned blank includes a striped blank or a honeycomb blank; The coefficient of friction of the surface lubrication adaptive composite material is 0.05 to 0.5.

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