A polytetrafluoroethylene dry film lubricant coating and a method of making the same

Abstract

The application discloses a polytetrafluoroethylene dry film lubricating coating and a preparation method thereof. The coating is obtained by cross-linking and curing components including the following components: epoxy resin 16-18 parts, polytetrafluoroethylene 6-8 parts, dicyandiamide 3-4 parts, zinc oxide 4-5 parts, flaky aluminum powder 0.5-1 part, nano silicon dioxide 0.3-0.4 part, surfactant 0.1-0.3 part and solvent, with the total mass being 100 parts. The application solves the problem of short wear life in the prior art and cannot adapt to various environments. The coating is well combined with the base material, has excellent flexibility and impact resistance, has excellent friction-reducing and wear-resistant performance and neutral salt spray corrosion resistance. The coating meets the requirements of high load bearing, long service life and neutral salt spray corrosion resistance of a mechanical system, achieves the purpose of friction reduction and wear resistance, improves the mechanical operation efficiency and reduces the maintenance cost.

Description

TECHNICAL FIELD

[0001] The present application relates to a dry film lubricating coating, in particular to a polytetrafluoroethylene dry film lubricating coating and a preparation method thereof. BACKGROUND

[0002] The first application of dry film lubrication technology came from NASA Lewis Research Center in 1946, and the dry film lubricating coating based on the dry film lubrication technology has broad market prospects. The dry film lubricating coating is applied to the surface of the parts after oil removal, sand blasting and cleaning by spraying process, to form a lubricating film with friction reduction and wear resistance, so as to prolong the service life of mechanical parts and reduce energy loss.

[0003] With the development of aerospace, marine and aviation industries, the dry film lubricating coating has higher requirements in high load, low friction coefficient and various environments. Therefore, it has great engineering application value to develop a high load and long life dry film lubricating coating suitable for harsh working conditions. As one of the main types of lubricating materials, the polytetrafluoroethylene dry film lubricating coating can be widely used in national defense, military and civil industries due to its low friction coefficient and excellent properties such as drug resistance. The polytetrafluoroethylene-based adhesive solid lubricant disclosed in the prior art (publication No. CN105132086A) only solves the lubrication and wear problem of moving parts under low load and high speed (490N, 0.43m / s). The friction coefficient is 0.1, and the wear life is only 280min. This obviously cannot meet the needs of modern industrial development. Therefore, it is of great significance to develop a new type of dry film lubricating coating suitable for various complex environments and low cost. SUMMARY

[0004] The purpose of the present application is to provide a polytetrafluoroethylene dry film lubricating coating and a preparation method thereof, which solves the problem of short wear life in the prior art and cannot adapt to various environments.

[0005] In order to achieve the above purpose, the present application provides a polytetrafluoroethylene dry film lubricating coating, wherein the coating is obtained by cross-linking and curing of components comprising the following mass fractions, based on 100 parts of total mass:

[0006] Epoxy resin 16-18 parts, polytetrafluoroethylene 6-8 parts, dicyandiamide 3-4 parts, zinc oxide 4-5 parts, flaky aluminum powder 0.5-1 parts, nano silicon dioxide 0.3-0.4 parts and surfactant 0.1-0.3 parts, the balance is organic solvent; the surfactant comprises: acetylenic diol polyoxyethylene ether.

[0007] The main components are polytetrafluoroethylene and flaky aluminum powder. In the polytetrafluoroethylene macromolecular chain, F atoms completely surround C atoms to form stable F-C chemical bonds, so that it has excellent corrosion resistance. The double helix structure of polytetrafluoroethylene molecules causes weak intermolecular attraction, which easily slides under load, thus showing excellent low friction coefficient. The shielding performance of flaky aluminum powder is remarkable, which blocks the direct contact between the substrate and the environmental medium, and easily forms a dense Al2O3 passivation film to improve corrosion resistance. At the same time, the addition of flaky aluminum powder enhances the load capacity of the coating. Polytetrafluoroethylene and flaky aluminum powder show good synergistic effect: when the mass fraction of polytetrafluoroethylene is 6-8 parts and the mass fraction of aluminum powder is 0.5-1 part, the polytetrafluoroethylene dry film lubricating coating prepared has the best performance. When the content of polytetrafluoroethylene is too low, the lubricating and corrosion resistance of the coating is reduced, the consumption rate of the coating is accelerated, and the physicochemical properties and friction properties of the coating are reduced; when the content of polytetrafluoroethylene is too high, the service life of the coating is prolonged but the load capacity of the coating is reduced. When the content of flaky aluminum powder is too low, the coating has lubricating effect, but the load capacity of the coating is significantly reduced, and the shielding effect of flaky aluminum powder is not obvious, which is easily penetrated by the environmental medium, eventually leading to the reduction of its performance; when the content of flaky aluminum powder is too high, the lubricating performance of the coating system is reduced, and the overall friction and wear resistance of the coating is reduced.

[0008] Preferably, the organic solvent is selected from any two or more of butanone, cyclohexanone and butyl acetate, which not only meets the requirements of spraying, but also meets the requirements of leveling performance of the coating after spraying. If the solvent volatilizes too fast, the coating is not easy to level; if it volatilizes too slowly, it is easy to appear bulging and other phenomena during the curing process, resulting in the decline of the performance of the coating.

[0009] More preferably, the solvent is butanone, cyclohexanone and butyl acetate, and the volume ratio of butanone, cyclohexanone and butyl acetate is (47-55):(15-22):(25-35).

[0010] More preferably, the volume ratio of butanone, cyclohexanone and butyl acetate is 52:22:26, 54:18:28, 52:20:28, 50:18:32, or 48:18:34.

[0011] More preferably, the concentration of butanone in the organic solvent is ≥99.0%, the concentration of cyclohexanone is ≥99.5%, and the concentration of butyl acetate is ≥99.5%.

[0012] Preferably, the epoxy resin is a yellow viscous liquid, and the epoxy value (equivalent / 100g) is 0.8-1.0 and the solid content is >98.5%.

[0013] Preferably, the particle size of the polytetrafluoroethylene micro powder is ≤5μm, the particle size of the zinc oxide is ≤3μm, and the particle size of the flaky aluminum powder is 2-5μm.

[0014] Preferably, the dicyandiamide is in powder form with purity ≥ 99%, the nano-silica has purity ≥ 99% and particle size of 50 nm, and the surfactant has mass percentage concentration ≥ 99%.

[0015] The epoxy resin serves as a binder, the polytetrafluoroethylene micro-powder serves as a lubricant, the zinc oxide and flaky aluminum powder serve as fillers and have an anti-corrosion effect, especially galvanic corrosion. The dicyandiamide serves as an initiator to promote the cross-linking reaction, the nano-silica serves as a filler to make the prepared coating more dense, and the surfactant promotes the uniform distribution of the binder and the fillers.

[0016] The present application provides a preparation method of the coating as described, which comprises:

[0017] (1) mixing and dissolving the epoxy resin and the solvent at room temperature to obtain a resin solution; mixing and stirring the polytetrafluoroethylene, dicyandiamide, zinc oxide, flaky aluminum powder, solvent and surfactant to obtain material A; mixing and dispersing the nano-silica, solvent and surfactant to obtain material B;

[0018] (2) mixing material A, material B and the resin solution obtained in step (1), adding a solvent, stirring, ball milling at room temperature, discharging, and obtaining a lubricating coating.

[0019] (3) coating the lubricating coating obtained in step (2) on the contact surface of a part by a spraying process, curing at a temperature of 170±5℃, cooling, and obtaining the polytetrafluoroethylene dry film lubricating coating on the contact surface of the part.

[0020] Preferably, in step (2), the stirring time is 0.5 h.

[0021] Preferably, in step (2), the ball milling time is 24 h.

[0022] Preferably, in step (3), the curing time is 1 h.

[0023] The present application also provides the use of the coating as described in the field of lubrication.

[0024] The polytetrafluoroethylene dry film lubricating coating and the preparation method thereof solve the problem of short wear life in the prior art and cannot adapt to various environments, and have the following advantages:

[0025] 1. The coating is prepared by using epoxy resin as a binder, polytetrafluoroethylene as a lubricant, flaky aluminum powder, zinc oxide and nano-silica as fillers, wherein dicyandiamide is introduced as an initiator to promote the cross-linking and curing of the epoxy resin, and the surfactant used is beneficial to the uniform dispersion of various raw materials.

[0026] 2、The polytetrafluoroethylene with particle size ≤5 μm improves the corrosion resistance and friction and wear performance of the coating, the flaky aluminum powder and zinc oxide further improve the corrosion resistance of the coating and improve the load bearing capacity of the coating, which makes up for the low load bearing capacity of the polytetrafluoroethylene, the addition of nano silicon dioxide enhances the compactness of the coating, hinders the direct contact between the parts and the environmental medium, thereby reducing the wear of the parts and improving the wear resistance.

[0027] 3、The coating of the present application has good combination with the base material, excellent flexibility and impact resistance, excellent friction reduction and wear resistance, and neutral salt spray corrosion resistance, and the coating can be used for a long time under the condition of 1000 N, 0.5 m / s, can run for not less than 80 min under the condition of 5000 N, 0.5 m / s, the dynamic and static friction coefficients remain consistent under the condition of 7 MPa, 0.08 mm / s, the specific value is 0.04, and there is no blistering and rusting phenomenon after 1000 h of test in the NaCl aqueous solution with a concentration of 50 g / L and a pH of 6.5-7.2.

[0028] 4、The coating of the present application meets the requirements of high load bearing, long service life and neutral salt spray corrosion resistance of the mechanical system, realizes the purpose of friction reduction and wear resistance, improves the mechanical operation efficiency, reduces the maintenance cost, and achieves the effect of energy saving and emission reduction. BRIEF DESCRIPTION OF DRAWINGS

[0029] Fig. 1 The wear life and friction coefficient diagram of the dry film lubricating coating prepared for the present application examples 1-5 under the condition of 1000 N, 0.5 m / s.

[0030] Fig. 2 The wear life and friction coefficient diagram of the dry film lubricating coating prepared for the present application examples 1-5 under the condition of 5000 N, 0.5 m / s. DETAILED DESCRIPTION

[0031] The technical solutions in the examples of the present application will be described clearly and completely below, obviously, the described examples are only a part of the examples of the present application, not all the examples. Based on the examples in the present application, all other examples obtained by those skilled in the art without creative labor belong to the scope of protection of the present application.

[0032] The raw materials used in the following examples are as follows:

[0033] The epoxy resin is a yellow viscous liquid, the epoxy value (equivalent / 100 g) is 0.8-1.0, and the solid content is >98.5%.

[0034] The polytetrafluoroethylene micropowder has a particle size of less than or equal to 5 μm, the zinc oxide has a particle size of less than or equal to 3 μm, and the flaky aluminum powder has a particle size of 2-5 μm.

[0035] The dicyandiamide is in powder form and has a purity of greater than or equal to 99%; the nanometer silicon dioxide has a purity of greater than or equal to 99% and a particle size of 50 nm; and the surfactant has a mass percentage concentration of greater than or equal to 99%.

[0036] Example 1

[0037] A polytetrafluoroethylene dry film lubricating coating, with a total mass of 100 g, comprises the following components by weight:

[0038] The epoxy resin is 16 g, the dicyandiamide is 3 g, the polytetrafluoroethylene is 6 g, the zinc oxide is 5 g, the flaky aluminum powder is 0.5 g, the nanometer silicon dioxide is 0.3 g, and the surfactant is 0.2 g, and the balance is a mixed solvent of 69 g; the mixed solvent is made of 48% methyl ketone, 18% cyclohexanone, and 34% butyl acetate by volume percentage.

[0039] A method for preparing the above polytetrafluoroethylene dry film lubricating coating, the method comprising:

[0040] (1) The epoxy resin is 16 g, the dicyandiamide is 3 g, the polytetrafluoroethylene is 6 g, the zinc oxide is 5 g, the flaky aluminum powder is 0.5 g, the nanometer silicon dioxide is 0.3 g, and the surfactant is 0.2 g, and the balance is a mixed solvent of 69 g; the mixed solvent is made of 48% methyl ketone, 18% cyclohexanone, and 34% butyl acetate by volume percentage.

[0041] (2) The epoxy resin is added to 22 g of the mixed solvent and dissolved thoroughly at room temperature to obtain a resin solution; the polytetrafluoroethylene, the dicyandiamide, the zinc oxide, and the flaky aluminum powder are simultaneously added to 18 g of the mixed solvent and the surfactant and stirred to obtain material A; the nanometer silicon dioxide is added to 9 g of the mixed solvent and the surfactant and ultrasonically dispersed to obtain material B;

[0042] (3) The materials A, B, and the resin solution obtained in step (2) are mixed, 20 g of the mixed solvent is added, and stirred for 0.5 h; the mixture is ball milled at room temperature for 24 h to discharge the material, and a lubricating coating is obtained;

[0043] (4) The lubricating coating obtained in step (3) is applied to the contact surface of a part that has been degreased, sandblasted, and cleaned by spraying, and is cured at a constant temperature of 170±5 °C for 1 h, and then cooled in the furnace to form a polytetrafluoroethylene dry film lubricating coating. The solid content of the polytetrafluoroethylene dry film lubricating coating is 31±2%.

[0044] Example 2

[0045] A polytetrafluoroethylene dry film lubricating coating, with a total mass of 100 g, is prepared from the following components by weight:

[0046] Epoxy resin 16.5 g, dicyandiamide 3.5 g, polytetrafluoroethylene 6.5 g, zinc oxide 4.5 g, flaky aluminum powder 0.6 g, nano-silica 0.3 g, and surfactant 0.1 g, with the balance being a mixed solvent. The mixed solvent is made up of 50% butanone, 18% cyclohexanone, and 32% butyl acetate by volume percentage.

[0047] The method for preparing the polytetrafluoroethylene dry film lubricating coating described above is basically the same as that of Example 1, except that:

[0048] In step (1), the epoxy resin 16.5 g, dicyandiamide 3.5 g, polytetrafluoroethylene 6.5 g, zinc oxide 4.5 g, flaky aluminum powder 0.6 g, nano-silica 0.3 g, and surfactant 0.1 g described above are weighed; and the mixed solvent is made up of 50% butanone, 18% cyclohexanone, and 32% butyl acetate by volume percentage.

[0049] Through the same operation as that of Example 1, a polytetrafluoroethylene dry film lubricating coating is formed. The solid content of the prepared polytetrafluoroethylene dry film lubricating coating is 32±2%.

[0050] Example 3

[0051] A polytetrafluoroethylene dry film lubricating coating is prepared from the following components by weight, with the total mass being 100 g:

[0052] Epoxy resin 16.5 g, dicyandiamide 4 g, polytetrafluoroethylene 7 g, zinc oxide 4 g, flaky aluminum powder 0.9 g, nano-silica 0.4 g, and surfactant 0.2 g, with the balance being a mixed solvent. The mixed solvent is made up of 52% butanone, 20% cyclohexanone, and 28% butyl acetate by volume percentage.

[0053] The method for preparing the polytetrafluoroethylene dry film lubricating coating described above is basically the same as that of Example 1, except that:

[0054] In step (1), the epoxy resin 16.5 g, dicyandiamide 4 g, polytetrafluoroethylene 7 g, zinc oxide 4 g, flaky aluminum powder 0.9 g, nano-silica 0.4 g, and surfactant 0.2 g described above are weighed; and the mixed solvent is made up of 52% butanone, 20% cyclohexanone, and 28% butyl acetate by volume percentage.

[0055] Through the same operation as that of Example 1, a polytetrafluoroethylene dry film lubricating coating is formed. The solid content of the prepared polytetrafluoroethylene dry film lubricating coating is 33±2%.

[0056] Example 4

[0057] A polytetrafluoroethylene dry film lubricating coating is prepared from the following components by weight, with the total mass being 100 g:

[0058] Epoxy resin 17.5 g, dicyandiamide 3.5 g, polytetrafluoroethylene 7.5 g, zinc oxide 4 g, flaky aluminum powder 1 g, nano-silica 0.3 g, and surfactant 0.2 g, with the balance being a mixed solvent. The mixed solvent was made up of 54% methyl ketone, 18% cyclohexanone, and 28% butyl acetate, by volume percent.

[0059] The polytetrafluoroethylene dry film lubricating coating was prepared in substantially the same manner as in Example 1, except that:

[0060] In step (1), the epoxy resin 17.5 g, dicyandiamide 3.5 g, polytetrafluoroethylene 8 g, zinc oxide 4 g, flaky aluminum powder 1 g, nano-silica 0.3 g, and surfactant 0.2 g were weighed out; and the mixed solvent was made up of 54% methyl ketone, 18% cyclohexanone, and 28% butyl acetate, by volume percent.

[0061] The polytetrafluoroethylene dry film lubricating coating was formed by the same procedure as in Example 1. The solid content of the polytetrafluoroethylene dry film lubricating coating produced was 34 ± 2%.

[0062] Example 5

[0063] A polytetrafluoroethylene dry film lubricating coating was prepared from the following components, in amounts by weight based on a total mass of 100 g:

[0064] Epoxy resin 16.5 g, dicyandiamide 4 g, polytetrafluoroethylene 8 g, zinc oxide 5 g, flaky aluminum powder 1 g, nano-silica 0.4 g, and surfactant 0.1 g, with the balance being a mixed solvent. The mixed solvent was made up of 52% methyl ketone, 22% cyclohexanone, and 26% butyl acetate, by volume percent.

[0065] The polytetrafluoroethylene dry film lubricating coating was prepared in substantially the same manner as in Example 1, except that:

[0066] In step (1), the epoxy resin 18 g, dicyandiamide 4 g, polytetrafluoroethylene 8 g, zinc oxide 5 g, flaky aluminum powder 1 g, nano-silica 0.4 g, and surfactant 0.1 g were weighed out; and the mixed solvent was made up of 52% methyl ketone, 22% cyclohexanone, and 26% butyl acetate, by volume percent.

[0067] The polytetrafluoroethylene dry film lubricating coating was formed by the same procedure as in Example 1. The solid content of the polytetrafluoroethylene dry film lubricating coating produced was 35 ± 2%.

[0068] Comparative Example 1

[0069] A polytetrafluoroethylene dry film lubricating coating was prepared in substantially the same manner as in Example 1, except that:

[0070] The mass of the polytetrafluoroethylene was adjusted from 6 g to 5.5 g.

[0071] The polytetrafluoroethylene dry film lubricating coating was prepared by the same method as in Example 1, except that:

[0072] In step (1), the mass of the polytetrafluoroethylene was adjusted from 6 g to 5.5 g;

[0073] The polytetrafluoroethylene dry film lubricating coating was formed by the same operation as in Example 1. The solid content of the prepared polytetrafluoroethylene dry film lubricating coating was 30.5 ± 2%.

[0074] Comparative Example 2

[0075] A polytetrafluoroethylene dry film lubricating coating was prepared by the same method as in Example 1, except that:

[0076] The mass of the polytetrafluoroethylene was adjusted from 6 g to 8.5 g.

[0077] The polytetrafluoroethylene dry film lubricating coating was prepared by the same method as in Example 1, except that:

[0078] In step (1), the mass of the polytetrafluoroethylene was adjusted from 6 g to 8.5 g;

[0079] The polytetrafluoroethylene dry film lubricating coating was formed by the same operation as in Example 1. The solid content of the prepared polytetrafluoroethylene dry film lubricating coating was 33.5 ± 2%.

[0080] Comparative Example 3

[0081] A polytetrafluoroethylene dry film lubricating coating was prepared by the same method as in Example 1, except that:

[0082] The mass of the flaky aluminum powder was adjusted from 0.5 g to 0.4 g.

[0083] The polytetrafluoroethylene dry film lubricating coating was prepared by the same method as in Example 1, except that:

[0084] In step (1), the mass of the flaky aluminum powder was adjusted from 0.5 g to 0.4 g;

[0085] The polytetrafluoroethylene dry film lubricating coating was formed by the same operation as in Example 1. The solid content of the prepared polytetrafluoroethylene dry film lubricating coating was 30.9 ± 2%.

[0086] Comparative Example 4

[0087] A polytetrafluoroethylene dry film lubricating coating was prepared by the same method as in Example 1, except that:

[0088] The mass of the flaky aluminum powder was adjusted from 0.5 g to 1.1 g.

[0089] The preparation method of the polytetrafluoroethylene dry film lubricating coating is basically the same as that of Example 1, except that:

[0090] In step (1), the mass of the sheet is adjusted from 0.5 g to 1.1 g;

[0091] The polytetrafluoroethylene dry film lubricating coating is formed by the same operation as that of Example 1. The solid content of the prepared polytetrafluoroethylene dry film lubricating coating is 31.6 ± 2%.

[0092] Test the performance of the polytetrafluoroethylene dry film lubricating coatings prepared in Examples 1-5 in Experimental Example 1

[0093] 1. Performance indicators

[0094] Test the performance of the dry film lubricating coatings prepared in Examples 1-5. The specific test conditions and test results are shown in Table 1.

[0095] Table 1 Performance indicators of polytetrafluoroethylene dry film lubricating coatings

[0096]

[0097]

[0098] As can be seen from Table 1, the polytetrafluoroethylene dry film lubricating coating prepared by the present application is a lubricating coating with excellent performance. The coating has good adhesion to the base material, excellent flexibility and impact resistance; and under the conditions of meeting the above performance, the coating also has excellent resistance to neutral salt spray corrosion.

[0099] 2. Wear life and friction coefficient

[0100] The wear life and friction coefficient of the dry film lubricating coatings prepared in Examples 1-5 are detected by a MR-H5 II type high-speed ring block wear tester, the test temperature is room temperature, the test conditions are 1000 N, 0.5 m / s or 5000 N, 0.5 m / s, and the test results are shown in Figs. 1-2 .

[0101] As shown in Fig. 1 , the wear life and friction coefficient diagram of the dry film lubricating coatings prepared in Examples 1-5 under the condition of 1000 N, 0.5 m / s.

[0102] As shown in Fig. 2 , the wear life and friction coefficient diagram of the dry film lubricating coatings prepared in Examples 1-5 under the condition of 5000 N, 0.5 m / s.

[0103] As shown in Figs. 1-2It can be known that the dry film lubricating coating prepared by the embodiments 1-5 has the wear life of 1853 min, 2083 min, 2054 min, 2106 min and 2191 min respectively and the friction coefficient of 0.055, 0.072, 0.068, 0.052 and 0.054 respectively under the condition of 1000N and 0.5m / s; and the wear life of 80 min, 81 min, 94 min, 114 min and 123 min respectively and the friction coefficient of 0.027, 0.030, 0.033, 0.031 and 0.028 respectively under the condition of 5000N and 0.5m / s. Therefore, the dry film lubricating coating has the advantages of high bearing capacity, low friction coefficient and good wear resistance, achieves the effect of reducing friction and wear, and improves the service life of mechanical parts.

[0104] 3. Dynamic and static friction coefficients

[0105] The dynamic and static friction coefficients of the dry film lubricating coating prepared by the embodiments 1-5 are detected on a test bench under the test conditions of 7MPa, 0.08mm / s, 4mm and 300, and the detection results are shown in Table 2.

[0106] Table 2: Dynamic and static friction coefficient performance indexes of polytetrafluoroethylene dry film lubricating coating

[0107]

[0108]

[0109] It can be known from Table 2 that the dynamic and static friction coefficient of the dry film lubricating coating is 0.04, which indicates that the dry film lubricating coating has the effect of reducing friction and wear, can meet the higher requirements of reliability and stability of mechanical systems, and can adapt to various complex environments.

[0110] Experimental example 2 analyzes the influence of the polytetrafluoroethylene dry film lubricating coating of comparative examples 1-4 on performance.

[0111] The performance of the polytetrafluoroethylene dry film lubricating coating prepared by comparative examples 1-4 is tested, and the specific test conditions and test results are shown in Table 3.

[0112] Table 3: Performance indexes of polytetrafluoroethylene dry film lubricating coating

[0113]

[0114] As shown in Table 3, the neutral salt spray resistance and the damp heat resistance of the dry film lubricating coating prepared by the comparative examples 1-4 are reduced. The wear life under the condition of 1000N, 0.5m / s is 457min, 519min, 776min and 216min respectively, and the friction coefficient is 0.24, 0.21, 0.15 and 0.28 respectively; the wear life under the condition of 5000N, 0.5m / s of the comparative example 1, 2 and 4 is 23min, 19min and 7min respectively, and the friction coefficient is 0.17, 0.15 and 0.26 respectively; the comparative example 3 has no wear life under the condition of 5000N, 0.5m / s.

[0115] In combination with Table 1-3 and Figs. 1-2 Compared with the examples 1-5, the dry film lubricating coating prepared by the comparative example 1 (the mass fraction of polytetrafluoroethylene is too low), the comparative example 2 (the mass fraction of polytetrafluoroethylene is too high), the comparative example 3 (the mass fraction of flaky aluminum powder is too low) and the comparative example 4 (the mass fraction of flaky aluminum powder is too high) has obviously reduced performance, so the mass percentage of polytetrafluoroethylene and flaky aluminum powder has significant influence on the performance of the prepared coating, and when the mass fraction of polytetrafluoroethylene is 6-8 parts and the mass fraction of aluminum powder is 0.5-1 part, the good synergistic effect is shown, and the polytetrafluoroethylene dry film lubricating coating prepared has the best performance, especially the wear life, the friction coefficient, the adhesion, the flexibility, the impact resistance, the neutral salt spray resistance and the damp heat resistance.

[0116] Although the content of the present application has been described in detail by the above preferred embodiments, it should be recognized that the above description should not be considered as the limitation of the present application. After the above content is read by the person skilled in the art, various modifications and substitutions of the present application will be obvious. Therefore, the protection scope of the present application should be defined by the appended claims.

Claims

1. A polytetrafluoroethylene dry film lubricating coating, characterized in that, Based on a total mass of 100 parts, the coating is obtained by cross-linking and curing the following components in parts by mass: The mixture consists of 16-18 parts epoxy resin, 6-8 parts polytetrafluoroethylene, 3-4 parts dicyandiamide, 4-5 parts zinc oxide, 0.5-1 part flake aluminum powder, 0.3-0.4 parts nano silica, and 0.1-0.3 parts surfactant, with the remainder being organic solvent. The surfactant comprises: acetylenic diol polyoxyethylene ether; The epoxy resin has an epoxy value of 0.8 to 1.0 and a solid content of >98.5%.

2. The coating according to claim 1, characterized in that, The solvent is selected from any two or more of butanone, cyclohexanone, and butyl acetate.

3. The coating according to claim 2, characterized in that, The solvent is butanone, cyclohexanone and butyl acetate, and the volume ratio of butanone, cyclohexanone and butyl acetate is (47~55):(15~22):(25~35).

4. The coating according to claim 1, characterized in that, The polytetrafluoroethylene micro powder has a particle size ≤ 5 μm, the zinc oxide has a particle size ≤ 3 μm, and the flake aluminum powder has a particle size of 2~5 μm.

5. The coating according to claim 1, characterized in that, The dicyandiamide has a purity of ≥99%; the nano-silica has a purity of ≥99% and a particle size of 50nm; and the surfactant has a mass percentage concentration of ≥99%.

6. A method for preparing a coating as described in any one of claims 1-5, characterized in that, The method includes: (1) At room temperature, epoxy resin and solvent are mixed and dissolved to obtain a resin solution; polytetrafluoroethylene, dicyandiamide, zinc oxide, flake aluminum powder, solvent and surfactant are mixed and stirred to obtain material A; nano silica, solvent and surfactant are mixed and dispersed to obtain material B; (2) Mix material A, material B and resin solution obtained in step (1), add solvent, stir, ball mill at room temperature and discharge to obtain lubricating coating; (3) The lubricating coating obtained in step (2) is applied to the contact surface of the part by spraying, cured at a temperature of 170±5℃, cooled, and the polytetrafluoroethylene dry film lubricating coating is obtained on the contact surface of the part.

7. The method according to claim 6, characterized in that, In step (2), the stirring time is 0.5 h; the ball milling time is 24 h.

8. The method according to claim 6, characterized in that, In step (3), the curing time is 1 hour.

9. The application of a coating as described in any one of claims 1-5 in the field of lubrication.

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