A polymer composite coating, its preparation method, and its application

Abstract

This application discloses a polymer composite coating, wherein the coating is solidified on the surface of a substrate, and the coating comprises a polymer matrix and a composite filler system dispersed therein; the polymer matrix is ​​polytetrafluoroethylene; the composite filler system comprises the following components: a first filler selected from at least one of molybdenum disulfide and graphene; a second filler selected from at least one of polyetheretherketone and inorganic fullerene nanoparticles; and a third filler selected from at least one of carbon nanofibers and graphene oxide; the mass ratio of the first filler, the second filler, and the third filler is 1:0.2~5:0.1~1, and the sum of the masses of the first filler, the second filler, and the third filler accounts for 6%~35% of the total mass of the coating. This application solves the problems of high friction coefficient, insufficient wear resistance, and weak substrate adhesion of traditional polymer coatings, and its comprehensive performance is significantly better than that of comparative schemes with single filler, no gradient, and isothermal curing, and has good engineering application value in the field of bearing friction reduction and wear resistance.

Description

Technical Field

[0001] This invention relates to the field of surface treatment technology, specifically to a polymer composite material coating, its preparation method, and its application. Background Technology

[0002] Friction and wear are among the main factors leading to the failure of mechanical parts, especially in Guizhou Province, where mountainous terrain makes the phenomenon of friction and wear failure in agricultural machinery bearings particularly prominent. Mechanical parts commonly employ liquid lubrication to reduce friction and wear damage. However, liquid lubrication systems face complex elastohydrodynamic lubrication conditions during operation. For example, when moving parts are under low speed, heavy load, and frequent start-stop conditions, the lubricating oil film is difficult to maintain stably and cannot achieve the expected stable lubrication effect. Furthermore, liquid lubrication systems require precise sealing structures to prevent leakage, resulting in high maintenance costs.

[0003] To address the aforementioned issues and achieve stable, long-term lubrication, solid self-lubricating materials are gradually becoming a research hotspot in lubrication systems. Polymers, due to their numerous superior properties such as low coefficient of friction, high wear resistance, and high load-bearing capacity, are widely used in lubrication systems for various mechanical components. Among them, polytetrafluoroethylene (PTFE), as a typical polymer lubricant, possesses an extremely low coefficient of friction and excellent chemical stability. New PTFE bearings use PTFE as the sliding inner layer, effectively avoiding the high maintenance costs associated with liquid lubrication. Its dry lubrication characteristics and long-term stability give it the potential to operate under extreme conditions.

[0004] In the field of filler research, MoS2 and graphene, due to their layered crystal structure, can form easily sheared transfer films on the friction pair surface, significantly reducing the coefficient of friction; PEEK, as a rigid thermoplastic polymer, has excellent wear resistance and load-bearing capacity; inorganic fullerene nanoparticles, with their unique spherical or ellipsoidal molecular structure, can act as ball bearings to reduce friction and wear during friction. However, most existing research focuses on how to improve the friction-reducing and wear-resistant properties of coatings through filler modification, while research on the bonding strength between the coating and the substrate remains insufficient. Summary of the Invention

[0005] The present invention aims to provide a polymer composite material coating, its preparation method, and its application, thereby improving the coating's bonding strength and service life.

[0006] To achieve the above objectives, the first aspect of this application provides the following technical solution: A polymer composite coating is solidified on a substrate surface. The coating comprises a polymer matrix and a composite filler system dispersed therein. The polymer matrix is ​​polytetrafluoroethylene (PTFE). The composite filler system comprises the following components: a first filler selected from at least one of molybdenum disulfide and graphene; a second filler selected from at least one of polyetheretherketone (PEEK) and inorganic fullerene nanoparticles; and a third filler selected from at least one of carbon nanofibers and graphene oxide. The mass ratio of the first filler, the second filler, and the third filler is 1:0.2~5:0.1~1, and the sum of the masses of the first filler, the second filler, and the third filler accounts for 6%~35% of the total mass of the coating.

[0007] Furthermore, the coating may be a single-layer structure or a multi-layer structure.

[0008] Furthermore, when the coating is a multilayer structure, the multilayer structure includes at least a bottom layer and a top layer, the bottom layer is the layer in contact with the substrate surface, and the top layer is the outermost layer away from the substrate surface; along the direction away from the substrate surface, the mass ratio of the first filler to the second filler in each layer is monotonically increasing or monotonically decreasing; the mass fraction of the third filler in each layer is monotonically decreasing.

[0009] Furthermore, the thickness of the coating is 50μm to 200μm.

[0010] The second aspect of this application provides the following technical solution: A method for preparing a polymer composite coating includes the following steps: Step S1: Mix polytetrafluoroethylene resin with the first filler, the second filler, and the third filler, add them to a solvent, and disperse them ultrasonically to obtain a composite slurry; Step S2: Pre-treat the substrate surface, wherein the pre-treatment is selected from at least one of plasma treatment, silane coupling agent coating or sandblasting. Step S3: Apply the composite slurry obtained in step S1 to the substrate surface after pretreatment in step S2 by spraying or spin coating to form a wet film; Step S4: The wet film formed in step S3 is cured by gradient temperature increase to obtain the polymer composite material coating.

[0011] Furthermore, the gradient temperature curing includes: a first stage of holding at 80~120℃ for 20~40 minutes, a second stage of holding at 200~280℃ for 10~20 minutes, and a third stage of holding at 380~400℃ for 30~60 minutes.

[0012] An application of a coating in bearings to reduce wear.

[0013] The working principle and beneficial effects of this invention: This application solves the problems of high friction coefficient, insufficient wear resistance and weak matrix bonding of traditional polymer coatings. Its comprehensive performance is significantly better than the comparative scheme of single filler, no gradient, and isothermal curing, and it has good engineering application value in the field of bearing friction reduction and wear resistance. Detailed Implementation

[0014] The following detailed description illustrates the specific implementation method: Example 1: Coating Composition The coating consists of 100 parts by weight of PTFE resin, 5 parts by weight of the first filler (MoS2), 1 part by weight of the second filler (PEEK), and 0.5 parts by weight of the third filler (carbon nanofibers). The total mass of the first, second, and third fillers accounts for 6.1% of the total mass of the coating.

[0015] The coating preparation method includes the following steps: Step S1: Mix PTFE resin and the above filler in proportion, add anhydrous ethanol, and ultrasonically disperse (45kHz, 100W, 40min) to obtain composite slurry.

[0016] Step S2: Perform plasma treatment on the stainless steel substrate (power 500W, treatment distance 15mm, scanning speed 100mm / s).

[0017] Step S3: Apply the composite slurry evenly to the substrate surface using a spray gun, controlling the spraying distance at 200mm and the spraying pressure at 0.3MPa to form a wet film with a thickness controlled at 80μm.

[0018] Step S4: Gradient curing: 80℃ / 30min→200℃ / 20min→380℃ / 45min, followed by furnace cooling.

[0019] Performance testing: (1) Coefficient of friction: 0.082 (M-200 friction and wear testing machine, load 50N, speed 200rpm, time 30min), (2) Wear rate: 2.1×10 -6 mm 3 / (N m), (3) Bond strength (scratch test): 85N, Coating hardness (Vickers hardness): 52HV.

[0020] Example 2: Coating Composition The coating consists of 100 parts by weight of PTFE resin, 4 parts by weight of the first filler (graphene), 4 parts by weight of the second filler (inorganic fullerene nanoparticles), and 2 parts by weight of the third filler (graphene oxide). The total mass of the first, second, and third fillers accounts for 9.1% of the total mass of the coating.

[0021] The preparation method is the same as in Example 1, but the gradient curing parameters are adjusted to: 100℃ / 30min→240℃ / 15min→390℃ / 40min.

[0022] Performance testing: Coefficient of friction: 0.071, Wear rate: 1.9 × 10⁻⁶ -6 mm 3 / (N m), bonding strength: 92N, coating hardness: 55HV.

[0023] Example 3: Coating Composition The coating consists of 100 parts by weight of PTFE resin, 3 parts by weight of the first filler (MoS2), 15 parts by weight of the second filler (PEEK), and 3 parts by weight of the third filler (carbon nanofibers). The total mass of the fillers accounts for 17.4% of the total mass of the coating.

[0024] The preparation method is the same as in Example 1, but the gradient curing parameters are adjusted to: 120℃ / 20min→280℃ / 10min→400℃ / 30min.

[0025] Performance testing: Coefficient of friction: 0.075, Wear rate: 2.8 × 10⁻⁶ -6 mm 3 / (N m), bonding strength: 78N, coating hardness: 58HV.

[0026] Example 4: Coating Composition The coating consists of 100 parts by weight of PTFE resin, 8 parts by weight of the first filler (graphene), 24 parts by weight of the second filler (inorganic fullerene), and 6 parts by weight of the third filler (graphene oxide). The total mass of the fillers accounts for 27.5% of the total mass of the coating.

[0027] Preparation method: Same as in Example 2.

[0028] Performance testing: Coefficient of friction: 0.088, Wear rate: 3.2 × 10⁻⁶ -6 mm 3 / (N m), bonding strength: 72N, coating hardness: 60HV.

[0029] Example 5: Double-layer structure Coating structure: base layer + top layer The substrate composition consists of 100 parts by weight of PTFE resin, 5 parts by weight of the first filler (MoS2), 2.5 parts by weight of the second filler (PEEK), and 2.5 parts by weight of the third filler (graphene oxide). The total mass of the fillers accounts for 9.1% of the total mass of the coating; the substrate thickness is 40 μm.

[0030] Surface composition: PTFE resin: 100 parts by weight, first filler (MoS2): 3 parts by weight, second filler (PEEK): 9 parts by weight, third filler (graphene oxide): 1 part by weight. Total filler mass as a percentage of total coating mass: 11.5%. Surface thickness: 60 μm.

[0031] The mass ratio of the first packing to the second packing decreases from 1:0.5 in the bottom layer to 1:3 in the top layer. The mass fraction of the third packing decreases from 2.5% in the bottom layer to 0.96% in the top layer.

[0032] Preparation method: First, prepare the base layer slurry according to the base layer formula, spray the base layer wet film, and pre-cur at 80℃ for 10min; then prepare the surface layer slurry according to the surface layer formula, and spray the surface layer wet film on the pre-cured base layer; perform gradient curing: 80℃ / 30min→200℃ / 20min→380℃ / 45min.

[0033] Performance testing: Coefficient of friction: 0.069, Wear rate: 1.7 × 10⁻⁶ -6 mm 3 / (N m), bonding strength: 105N, coating hardness: 57HV, interlaminar shear strength: 32MPa.

[0034] Example 6: Three-layer structure Coating structure: base layer + intermediate layer + top layer The substrate composition consists of 100 parts by weight of PTFE resin, 3 parts by weight of the first filler (graphene), 12 parts by weight of the second filler (PEEK), and 3 parts by weight of the third filler (carbon nanofibers). The total mass of the fillers accounts for 15.3% of the total mass of the coating; the substrate thickness is 30 μm.

[0035] Intermediate layer composition: 100 parts by weight of PTFE resin, 4 parts by weight of first filler (graphene), 8 parts by weight of second filler (PEEK), and 1.5 parts by weight of third filler (carbon nanofibers). The total mass of fillers accounts for 11.9% of the total mass of the coating; the thickness of the intermediate layer is 30 μm.

[0036] Surface composition: 100 parts by weight of PTFE resin, 5 parts by weight of first filler (graphene), 2.5 parts by weight of second filler (PEEK), and 0.5 parts by weight of third filler (carbon nanofibers). The total mass of fillers accounts for 7.4% of the total mass of the coating; the surface thickness is 60 μm.

[0037] The mass ratio of the first packing to the second packing decreases from 1:4 in the bottom layer to 1:2 in the middle layer and then to 1:0.5 in the top layer. The mass fraction of the third packing decreases from 2.5% in the bottom layer to 1.32% in the middle layer and then to 0.46% in the top layer.

[0038] Preparation method: Spray the base coat, intermediate coat, and top coat sequentially, and pre-cur at 80℃ for 5 minutes after each coat. Overall gradient curing: 90℃ / 30min → 220℃ / 15min → 390℃ / 35min.

[0039] Performance testing: Coefficient of friction: 0.065, Wear rate: 1.5 × 10⁻⁶ -6 mm 3 / (N m), bond strength: 112N, interlaminar shear strength: 35MPa, coating hardness: 60HV.

[0040] Example 7: Three-layer structure Coating structure: base layer + intermediate layer + top layer The substrate composition consists of 100 parts by weight of PTFE resin, 5 parts by weight of the first filler (graphene), 2.5 parts by weight of the second filler (PEEK), and 0.5 parts by weight of the third filler (carbon nanofibers). The total mass of the fillers accounts for 7.4% of the total mass of the coating; the substrate thickness is 30 μm.

[0041] Intermediate layer composition: 100 parts by weight of PTFE resin, 4 parts by weight of first filler (graphene), 8 parts by weight of second filler (PEEK), and 1.5 parts by weight of third filler (carbon nanofibers). The total mass of fillers accounts for 11.9% of the total mass of the coating; the thickness of the intermediate layer is 30 μm.

[0042] Surface composition: 100 parts by weight of PTFE resin, 3 parts by weight of first filler (graphene), 12 parts by weight of second filler (PEEK), and 3 parts by weight of third filler (carbon nanofibers). The total mass of fillers accounts for 15.3% of the total mass of the coating; surface thickness: 60 μm.

[0043] The mass ratio of the first packing to the second packing increases from 1:0.5 in the bottom layer to 1:2 in the middle layer and then to 1:4 in the top layer. The mass fraction of the third packing decreases from 0.46% in the bottom layer to 1.32% in the middle layer and then to 2.5% in the top layer.

[0044] Preparation method: Spray the base coat, intermediate coat, and top coat sequentially, and pre-cur at 80℃ for 5 minutes after each coat. Overall gradient curing: 90℃ / 30min → 220℃ / 15min → 390℃ / 35min.

[0045] Performance testing: Coefficient of friction: 0.067, Wear rate: 1.6 × 10⁻⁶ -6 mm 3 / (N m), bond strength: 110N, interlaminar shear strength: 34MPa, coating hardness: 59HV.

[0046] Comparative Example 1: No first packing Coating composition: 100 parts by weight of PTFE resin, 0 parts by weight of first filler, 5 parts by weight of second filler (PEEK), and 1 part by weight of third filler (carbon nanofibers). The total mass of fillers accounts for 5.7% of the total mass of the coating. The preparation method is the same as in Example 1.

[0047] Performance testing: Coefficient of friction: 0.135, Wear rate: 5.8 × 10⁻⁶ -6 mm 3 / (N m), Bond strength: 62N.

[0048] Without the first filler, the coefficient of friction increased significantly (from 0.082 in Example 1 to 0.135), and the wear rate also increased significantly.

[0049] Comparative Example 2: No second packing Coating composition: 100 parts by weight of PTFE resin, 5 parts by weight of first filler (MoS2), 0 parts by weight of second filler, and 0.5 parts by weight of third filler (carbon nanofibers). The total mass of fillers accounts for 5.2% of the total mass of the coating. The preparation method is the same as in Example 1. Performance testing: coefficient of friction: 0.078, wear rate: 4.2 × 10⁻⁶. -6 mm 3 / (N m), Bond strength: 58N.

[0050] The wear rate increased significantly after the second filler was missing (from 2.1 × 10⁻⁶ in Example 1). -6 Increased to 4.2×10 -6 The bonding strength also decreased significantly.

[0051] Comparative Example 3: No third packing Coating composition: 100 parts by weight of PTFE resin, 5 parts by weight of first filler (MoS2), 5 parts by weight of second filler (PEEK), and 0 parts by weight of third filler. The sum of the mass of the first filler and the second filler accounts for 9.1% of the total mass of the coating. The preparation method is the same as in Example 1.

[0052] Performance testing: Without the third filler, the coating's bond strength decreased significantly, from 85 N in Example 1 to 74 N, and the wear rate decreased from 2.1 × 10⁻⁶ in Example 1. -6 Increased to 3.6×10 -6 The coefficient of friction also increased.

[0053] Comparative Example 4: Coating composition: 100 parts by weight of PTFE resin, 2.5 parts by weight of first filler (MoS2), 20 parts by weight of second filler (PEEK), and 1 part by weight of third filler (carbon nanofiber). The total mass of fillers accounts for 19.0% of the total mass of the coating. Preparation method: same as in Example 1.

[0054] Performance testing: Coefficient of friction: 0.095, Wear rate: 3.8 × 10⁻⁶ -6 mm 3 / (N m), Bond strength: 68N.

[0055] Comparative conclusion: The ratio of the first packing material to the second packing material is too high, exceeding the range of 1:0.2~5, which leads to a comprehensive decline in performance due to agglomeration.

[0056] Comparative Example 5: The coating composition is the same as in Example 2. Preparation method: Isothermal curing is adopted, and the temperature is directly kept at 380℃ for 60 minutes (without gradient temperature rise section).

[0057] Performance testing: Coefficient of friction: 0.089, Wear rate: 3.5 × 10⁻⁶ -6 mm 3 / (N m), Bond strength: 68N.

[0058] Comparative conclusion: Without the gradient curing process, the coating bonding strength decreased significantly from 92N in Example 2 to 68N, and the wear rate increased.

[0059] Comparative Example 6 (multi-layer structure, with the same filler ratio in each layer) Coating structure: Two layers, with the bottom layer and the top layer using the same composition (same as in Example 2). Preparation method: Same as in Example 5.

[0060] Performance testing: Coefficient of friction: 0.078, Wear rate: 2.5 × 10⁻⁶ -6 mm 3 / (N m), Bond strength: 82N.

[0061] In summary, this application solves the problems of high friction coefficient, insufficient wear resistance, and weak matrix adhesion of traditional polymer coatings. Its overall performance is significantly better than that of comparative schemes with single filler, no gradient, and isothermal curing, and it has good engineering application value in the field of bearing friction reduction and wear resistance.

[0062] It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solution of this invention. These modifications and improvements should also be considered within the scope of protection of this invention, and will not affect the effectiveness of the invention or the practicality of the patent. The scope of protection claimed in this application shall be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A polymer composite coating, the coating being bonded to a substrate surface, the coating comprising a polymer matrix and a composite filler system dispersed therein; the polymer matrix being polytetrafluoroethylene; characterized in that: The composite filler system comprises the following components: a first filler selected from at least one of molybdenum disulfide and graphene; a second filler selected from at least one of polyetheretherketone and inorganic fullerene nanoparticles; and a third filler selected from at least one of carbon nanofibers and graphene oxide. The mass ratio of the first filler, the second filler and the third filler is 1:0.2~5:0.1~1, and the sum of the masses of the first filler, the second filler and the third filler accounts for 6%~35% of the total mass of the coating.

2. The polymer composite material coating according to claim 1, characterized in that: The coating may be a single-layer or multi-layer structure.

3. The polymer composite material coating according to claim 2, characterized in that: When the coating is a multilayer structure, the multilayer structure includes at least a bottom layer and a top layer. The bottom layer is the layer in contact with the substrate surface, and the top layer is the outermost layer away from the substrate surface. Along the direction away from the substrate surface, the mass ratio of the first filler to the second filler in each layer increases or decreases monotonically; the mass fraction of the third filler in each layer decreases monotonically.

4. The polymer composite material coating according to claim 3, characterized in that: The thickness of the coating is 50μm to 200μm.

5. The method for preparing the polymer composite coating according to any one of claims 1 to 4, characterized in that: Includes the following steps: Step S1: Mix polytetrafluoroethylene resin with the first filler, the second filler, and the third filler, add them to a solvent, and disperse them ultrasonically to obtain a composite slurry; Step S2: Pre-treat the substrate surface, wherein the pre-treatment is selected from at least one of plasma treatment, silane coupling agent coating or sandblasting. Step S3: Apply the composite slurry obtained in step S1 to the substrate surface after pretreatment in step S2 by spraying or spin coating to form a wet film; Step S4: The wet film formed in step S3 is cured by gradient temperature increase to obtain the polymer composite material coating.

6. The preparation method according to claim 5, characterized in that: The gradient temperature curing process includes: a first stage of holding at 80~120℃ for 20~40 minutes, a second stage of holding at 200~280℃ for 10~20 minutes, and a third stage of holding at 380~400℃ for 30~60 minutes.

7. The application of the coating according to any one of claims 1 to 4 in reducing wear in bearings.