Phenolic resin lubricating coating and preparation method thereof

Abstract

The invention provides a phenolic resin lubricating coating and a preparation method thereof, and belongs to the technical field of polymer self-lubricating composite materials. The phenolic resin lubricating coating comprises the following components in percentage by mass: 89%-99% of phenolic resin, 0.5%-10% of lanthanum oxide and 0.5%-1% of an auxiliary agent. The lanthanum oxide is added for formula optimization, other solid lubricants are omitted, the bearing capacity and the easy-to-shear lubrication characteristic of the lanthanum oxide are utilized, a transfer film with the solid lubrication characteristic and the high bearing capacity is generated in the friction process of PF under the friction shear action, direct contact of a friction matching pair is avoided, and the friction matching pair is prevented from being damaged. According to the lubricating oil, the defect of an oil film under boundary lubrication is remarkably overcome, the frictional wear between a phenolic resin lubricating coating and a metal matching pair is greatly improved, and the lubricating oil shows excellent tribological performance under a harsh oil lubrication condition and has relatively low friction coefficient and wear rate.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer self-lubricating composites, and particularly relates to a phenolic resin lubricating coating and a preparation method thereof. Background Art

[0002] As an environmentally friendly alternative, polymer self-lubricating materials can avoid the use of lubricating additives and even lubricating oils. Polymer self-lubricating materials achieve interface lubrication by forming a transfer film at the friction interface or relying on their own low shear properties, without the need to add additional lubricating oil, thus avoiding environmental pollution problems. In addition, polymer materials have the advantages of strong designability, chemical corrosion resistance, and strong adaptability, and can provide stable tribological properties under harsh working conditions. Thermosetting phenolic resin (PF) is a resin synthesized by the addition and condensation reaction of phenol and formaldehyde under the action of an alkaline catalyst. This resin has excellent self-lubricity, mechanical strength, and chemical stability, and is widely used in military, construction, aerospace and other fields. However, pure phenolic resin also has defects such as high brittleness, poor toughness, large friction coefficient, insufficient wear resistance, and short service life, which limit its application under harsh working conditions. In order to further improve the tribological properties of phenolic resin, related technologies have prepared a phenolic resin lubricating coating filled with rare earth compound cerium oxide, but other types of solid lubricants such as molybdenum disulfide still need to be added. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide a phenolic resin lubricating coating and a preparation method thereof. The phenolic resin lubricating coating of the present invention does not contain other solid lubricants and has good lubrication performance.

[0004] In order to achieve the above invention purpose, the present invention provides the following technical solutions:

[0005] The present invention provides a phenolic resin lubricating coating, which is composed of the following components in mass percentage: 89% - 99% of phenolic resin, 0.5% - 10% of lanthanum oxide, and 0.5% - 1% of an auxiliary agent.

[0006] Preferably, the phenolic resin lubricating coating is composed of the following components in mass percentage: 94% - 98.5% of phenolic resin, 0.5% - 5% of lanthanum oxide, and 1% of an auxiliary agent.

[0007] Preferably, the phenolic resin lubricating coating is composed of the following components in mass percentage: 98.5% of phenolic resin, 0.5% of lanthanum oxide, and 1% of an auxiliary agent.

[0008] Preferably, the phenolic resin lubricating coating is composed of the following components in mass percentage: 94% of phenolic resin, 5% of lanthanum oxide, and 1% of an auxiliary agent.

[0009] Preferably, the phenolic resin lubricating coating is composed of the following components by mass percentage: 89% of phenolic resin, 10% of lanthanum oxide, and 1% of additives.

[0010] Preferably, the particle size of the lanthanum oxide is 1 - 30 μm.

[0011] Preferably, the additives include a defoaming agent and a leveling agent. The mass ratio of the defoaming agent to the leveling agent in the additives is 0:10 - 10:0, and the masses of both the defoaming agent and the leveling agent are not 0.

[0012] Preferably, the mass ratio of the defoaming agent to the leveling agent in the additives is 1:1.

[0013] The present invention also provides a preparation method of the phenolic resin lubricating coating described in the above technical solution, including the following steps:

[0014] Mix the phenolic resin, lanthanum oxide, and additives and grind them to obtain a phenolic resin composite material;

[0015] Mix the phenolic resin composite material with an organic solvent to obtain a phenolic resin composite coating;

[0016] Coat the phenolic resin composite coating on the surface of a preheated substrate to obtain the phenolic resin lubricating coating.

[0017] Preferably, the heat treatment process of the preheated substrate includes: starting from 60°C, heating to 140°C at a heating rate of 15 - 25°C / min, holding for 1 - 2 h, and then naturally cooling to room temperature.

[0018] The present invention provides a phenolic resin lubricating coating, which is composed of the following components by mass percentage: 89% - 99% of phenolic resin, 0.5% - 10% of lanthanum oxide, and 0.5% - 1% of additives.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] Through the addition of lanthanum oxide for formula optimization, the present invention omits other solid lubricants and makes clever use of the load - bearing capacity and easy - shear lubrication characteristics of lanthanum oxide. Under the action of frictional shear, PF generates a transfer film with solid lubrication characteristics and high load - bearing capacity during the friction process, avoiding the direct contact of the friction pair, significantly making up for the deficiency of the oil film under boundary lubrication, greatly improving the friction and wear between the phenolic resin lubricating coating and the metal pair, showing excellent tribological properties under harsh oil lubrication conditions, having a low friction coefficient and wear rate, being able to effectively adapt to the boundary lubrication working condition, being particularly suitable for the application of self - lubricating coatings on the surface of automotive engine piston skirts, significantly reducing the friction between the piston and the cylinder liner, effectively avoiding the occurrence of piston scuffing, and thus greatly improving the reliability and service life of moving components.

[0021] The polymer composite coating prepared by the present invention. The present invention also provides a preparation method for the phenolic resin lubricating coating described in the above technical solution. The preparation method of the present invention is simple in operation and suitable for industrial application. Description of the Drawings

[0022] Figure 1 SEM images of the coatings obtained in Example 1 and Comparative Example 1, where (a) is for Example 1 and (b) is for Comparative Example 1;

[0023] Figure 2 Cross-cut test results of the coatings obtained in Example 1 and Comparative Example 1, where (a) is for Example 1 and (b) is for Comparative Example 1. Detailed Description of the Invention

[0024] The present invention provides a phenolic resin lubricating coating, which is composed of the following components in mass percentages: phenolic resin 89% - 99%, lanthanum oxide 0.5% - 10% and additives 0.5% - 1%.

[0025] In the present invention, unless otherwise specified, the raw materials used are all commercially available products in the art.

[0026] In the present invention, the phenolic resin lubricating coating preferably consists of the following components in mass percentages: phenolic resin 94% - 98.5%, lanthanum oxide 0.5% - 5% and additives 1%, specifically phenolic resin 98.5%, lanthanum oxide 0.5% and additives 1% or phenolic resin 94%, lanthanum oxide 5% and additives 1% or phenolic resin 89%, lanthanum oxide 10% and additives 1%.

[0027] In the present invention, the phenolic resin is preferably a thermosetting phenolic resin liquid.

[0028] In the present invention, the particle size of the lanthanum oxide is preferably 1 - 30 μm, specifically it can be 1, 5, 10, 15, 20, 25 or 30 μm. Controlling the particle size of the lanthanum oxide within the above range can balance the lubrication and anti-wear properties, avoiding that too small particle size is beneficial for lubrication but not for anti-wear, and too large particle size is beneficial for anti-wear but not for lubrication. Lanthanum oxide can promote the formation of a stable transfer film and improve the tribological properties of the phenolic resin lubricating coating.

[0029] In the present invention, the lanthanum oxide is used as a rare earth filler. By adding lanthanum oxide to optimize the formulation, other solid lubricants are omitted. The load-bearing capacity and easy-shear lubrication characteristics of lanthanum oxide are ingeniously utilized. Under the action of frictional shear, a transfer film with solid lubrication characteristics and high load-bearing capacity is generated by PF during the friction process, avoiding the direct contact of the friction pair, significantly making up for the deficiency of the oil film under boundary lubrication, greatly improving the friction and wear between the phenolic resin lubricating coating and the metal pair, showing excellent tribological properties under harsh oil lubrication conditions, having a low friction coefficient and wear rate. The content of the lanthanum oxide is controlled within 0.5% - 10%, avoiding the problems of poor load-bearing capacity and high wear rate of the coating caused by too little lanthanum oxide, and at the same time, there is no problem of reducing the mechanical properties, coating adhesion and interfacial friction stability of the coating caused by too much lanthanum oxide.

[0030] In the present invention, the additives preferably include defoamers and leveling agents. The mass ratio of the defoamer to the leveling agent in the additives is preferably 0:10 - 10:0, and the masses of both the defoamer and the leveling agent are preferably not 0, more preferably 1:1.

[0031] In the present invention, the defoamer preferably includes one or more of BYK1811, BYK1790 and BYK045, and the leveling agent preferably includes one or more of BYK352, BYK310 and BYK322.

[0032] The present invention also provides a preparation method of the phenolic resin lubricating coating according to the above technical solution, including the following steps:

[0033] Mix the phenolic resin, lanthanum oxide and additives and grind them to obtain a phenolic resin composite material;

[0034] Mix the phenolic resin composite material with an organic solvent to obtain a phenolic resin composite coating;

[0035] Coat the phenolic resin composite coating on the surface of a preheated substrate to obtain the phenolic resin lubricating coating.

[0036] In the present invention, the phenolic resin, lanthanum oxide and additives are mixed and ground to obtain a phenolic resin composite material.

[0037] In the present invention, the mixing is preferably carried out by stirring in a high-speed mixer. The conditions of the stirring preferably include: the vacuum degree is -1.0×10 5 Pa, the rotation speed is 500 - 3000 r / min, specifically it can be 500, 1000, 1500, 2000, 2500 or 3000 r / min, and the time is 10 - 15 min, specifically it can be 10 or 15 min.

[0038] In the present invention, the grinding is preferably three-roll grinding, and the conditions for the three-roll grinding preferably include: grinding three times with a three-roll grinder, grinding the material to a particle size of 20 - 30 μm for the first time, grinding the material to a particle size of 10 - 20 μm for the second time, and grinding the material to a particle size of 5 - 10 μm for the third time. More preferably, it is carried out in a three-roll grinder. Through multiple gradient grindings, the dispersion uniformity of lanthanum oxide in phenolic resin can be improved. In the present invention, a three-roll grinder is used for grinding. Utilizing its high-efficiency shearing, the size of the particles in the coating is reduced, the dispersion effect of lanthanum oxide in the resin is improved, the phenomenon of uneven particle distribution of lanthanum oxide in the coating is avoided, and finally, the service life and reliability of the phenolic resin lubricating coating under harsh oil lubrication conditions are improved.

[0039] After obtaining the phenolic resin composite material, the present invention mixes the phenolic resin composite material with an organic solvent to obtain a phenolic resin composite coating.

[0040] In the present invention, the organic solvent preferably includes methanol and a co-solvent, and the co-solvent preferably includes one or more of absolute ethanol, N,N-dimethylformamide (DMF), and N-methylpyrrolidone (NMP).

[0041] In the present invention, the mass ratio of methanol to the co-solvent in the organic solvent is preferably 1:2 - 1:7, specifically, it can be 1:2, 1:5, or 1:7. Limiting the mass ratio of methanol to the co-solvent within the above range can better dissolve the phenolic resin.

[0042] In the present invention, the mass ratio of the phenolic resin composite material to the organic solvent is preferably 1:0.5 - 1:10, specifically, it can be 1:0.5, 1:1, 1:5, or 1:10.

[0043] In the present invention, the mixing of the phenolic resin composite material and the organic solvent is preferably stirring. The rotation speed of the stirring is preferably 500 - 3000 r / min, specifically, it can be 500, 1000, 1500, 2000, 2500, or 3000 r / min, and the time is preferably 10 - 15 min, specifically, it can be 10 or 15 min.

[0044] After obtaining the phenolic resin composite coating, the present invention coats the phenolic resin composite coating on the surface of a preheated substrate to obtain the phenolic resin lubricating coating.

[0045] The present invention preferably pours the phenolic resin composite coating into a spray gun and sprays it onto the surface of the preheated substrate. The present invention has no special limitations on the specific parameters of the spraying, and a method well-known to those skilled in the art can be adopted.

[0046] In the present invention, the heat treatment process of the preheated substrate preferably includes: starting from 60°C, heating up to 140°C at a heating rate of 15 - 25°C / min, keeping warm for 1 - 2 h, and then naturally cooling to room temperature.

[0047] In the present invention, the preheated substrate is preferably an aluminum plate, a tinplate or a copper plate.

[0048] The phenolic resin lubricating coating prepared by the present invention exhibits excellent tribological properties under harsh oil lubrication conditions, has a low friction coefficient and wear rate, can effectively adapt to the boundary lubrication working condition, is particularly suitable for the application of self-lubricating coating on the surface of the piston skirt of an automotive engine, can significantly reduce the friction between the piston and the cylinder liner, effectively avoid the occurrence of piston scuffing, and thus greatly improve the reliability and service life of the moving components.

[0049] The technical solutions in the present invention will be clearly and completely described below with reference to the embodiments in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0050] Example 1

[0051] The phenolic resin lubricating coating is composed of the following components by mass: 94 g of phenolic resin, 5 g of lanthanum oxide (15 μm), and 1 g of additives (where 0.5 g of defoamer BYK181 and 0.5 g of leveling agent BYK352).

[0052] The preparation method includes the following steps:

[0053] Weigh according to the ratio;

[0054] Add lanthanum oxide, additives and phenolic resin into a high-speed mixer, stir for 10 min under the conditions of a vacuum degree of -1.0×10 5 Pa and a rotation speed of 1500 r / min, and then grind three times with a three-roll grinder. The first grinding is to a material particle size of 20 - 30 μm, the second grinding is to a material particle size of 10 - 20 μm, and the third grinding is to a material particle size of 5 - 10 μm to obtain a phenolic resin composite material;

[0055] Add an organic solvent with a ratio of n-propanol to absolute ethanol of 1:2 (g / g) into the phenolic resin composite material, and stir and mix at 1500 r / min for 10 min to obtain a phenolic resin composite coating;

[0056] Pour the phenolic resin composite coating into a spray gun and spray it onto the surface of the heat-treated aluminum plate to obtain a phenolic resin lubricating coating with a thickness of 30 μm, and investigate its tribological properties. Among them: The heat treatment conditions refer to preheating in a blast drying oven at 60 °C, heating to 140 °C at a heating rate of 15 °C / min, holding for 1 h, and then naturally cooling to room temperature.

[0057] Example 2

[0058] The phenolic resin lubricating coating consists of the following components by mass: 98.5 g of phenolic resin, 0.5 g of lanthanum oxide (15 μm), and 1 g of additives (including 0.5 g of defoamer BYK181 and 0.5 g of leveling agent BYK352).

[0059] The preparation method is the same as that of Example 1.

[0060] Example 3

[0061] The phenolic resin lubricating coating consists of the following components by mass: 89 g of phenolic resin, 10 g of lanthanum oxide (15 μm), and 1 g of additives (including 0.5 g of defoamer BYK181 and 0.5 g of leveling agent BYK352).

[0062] The preparation method is the same as that of Example 1.

[0063] Comparative Example 1

[0064] The phenolic resin lubricating coating consists of the following components by mass: 99 g of phenolic resin and 1 g of additives (including 0.5 g of defoamer BYK181 and 0.5 g of leveling agent BYK352).

[0065] Its preparation method is the same as that of Example 1, except that lanthanum oxide is not added.

[0066] Comparative Example 2

[0067] The phenolic resin lubricating coating consists of the following components by mass: 89 g of phenolic resin, 10 g of cerium oxide (15 μm), and 1 g of additives (including 0.5 g of defoamer BYK181 and 0.5 g of leveling agent BYK352).

[0068] Its preparation method is the same as that of Example 1, except that lanthanum oxide is replaced by cerium oxide.

[0069] Comparative Example 3

[0070] The phenolic resin lubricating coating consists of the following components by mass: 87 g of phenolic resin, 12 g of lanthanum oxide (15 μm), and 1 g of additives (including 0.5 g of defoamer BYK181 and 0.5 g of leveling agent BYK352).

[0071] Its preparation method is the same as that of Example 1.

[0072] Comparative Example 4

[0073] The phenolic resin lubricating coating consists of the following components by mass: 98.9 g of phenolic resin, 0.1 g of lanthanum oxide (15 μm), and 1 g of additives (including 0.5 g of defoamer BYK181 and 0.5 g of leveling agent BYK352).

[0074] Its preparation method is the same as that of Example 1.

[0075] The coatings obtained in Example 1 and Comparative Example 1 were respectively subjected to electron microscopy scanning, as Figure 1 shown, where (a) is Example 1 and (b) is Comparative Example 1. It can be seen from the figure that compared with Comparative Example 1, the thickness of the coating obtained in Example 1 is 30 μm, and the particles in the coating are uniformly dispersed in the PF matrix without agglomeration.

[0076] The adhesion strength of the coatings obtained in Example 1 and Comparative Example 1 was tested by the cross-cut test according to ISO 2409:2020, as Figure 2 shown, where (a) is Example 1 and (b) is Comparative Example 1. It can be found that there is no obvious peeling at the cross of the scratches of the coating in Example 1, and the adhesion grade is 0. While a large amount of coating peeling occurred at the cross of the scratches of the coating in Comparative Example 1, and the corresponding adhesion grade of the coating is 5. This is because the addition of lanthanum oxide particles in the coating increases the specific surface area and the number of interfaces of the coating, which helps to better disperse stress, reduce crack propagation, and thus improve the adhesion strength of the coating.

[0077] Tribological property test

[0078] Friction experiments were carried out on the coatings obtained in the examples and comparative examples, and a high-speed ring-block tribometer was used for testing. The aluminum plate with the coating was machined into 25×10×4 mm 3 , and the counter-part was 304 stainless steel. The counter-part was polished with sandpaper of the same mesh number to obtain the same surface roughness Ra = 0.2 μm.

[0079] The test conditions were as follows: test load 100 N, sliding speed 0.2 m / s, duration 1 h, and the counter-part was immersed in a cavity filled with poly-α-olefin (PAO) oil. After the friction experiment, the width of the wear scar was measured by an optical microscope, and the wear rate Ws was calculated using the formula.

[0080] The calculation formula of the wear rate is as follows:

[0081]

[0082] Where: L′ and W are the length and width of the wear scar (mm), F is the load (N), L is the total sliding distance (m), and r is the radius of the steel ring (mm).

[0083] The calculation results of the average friction coefficient and wear rate of the obtained materials are shown in Table 1. It can be seen from Table 1 that the phenolic resin lubricating coating of the present invention has significant friction reduction and anti-wear characteristics compared with the comparative examples. The friction coefficient and wear rate are greatly reduced compared with the pure phenolic coating. It can have good lubrication performance without solid lubricants. Moreover, the experimental results of Comparative Examples 3 and 4 prove that when the content of lanthanum oxide is 12 wt% and 0.1 wt%, the tribological performance of the coating decreases compared with that when the content of lanthanum oxide is 0.5 wt% - 10 wt%.

[0084] Table 1 Average friction coefficient and wear rate of examples and comparative examples

[0085] Coefficient of friction <![CDATA[Wear rate (10 -6 mm 3 / Nm)]]> Example 1 0.024 2.789 Example 2 0.069 4.698 Example 3 0.027 3.304 Comparative Example 1 0.119 5.897 Comparative Example 2 0.089 4.702 Comparative Example 3 0.125 5.954 Comparative Example 4 0.115 5.532

[0086] In summary, under the action of frictional shear, the coating with relatively weak mechanical properties undergoes material spalling and transfers to the surface of the metal counterbody. Then, the lanthanum oxide released to the friction interface is further ground into smaller nanoparticles and uniformly dispersed in the transfer film. Among them, the high-strength lanthanum oxide improves the load-bearing capacity of the transfer film. The transfer film with solid lubrication characteristics and high load-bearing capacity avoids the direct scratching of the friction pair, significantly compensates for the deficiency of the oil film under boundary lubrication, and greatly improves the friction and wear between the coating and the metal counterbody. Due to its large brittleness and low toughness caused by its molecular structure and high cross-linking degree, the pure phenolic coating is prone to crack and spall during friction. Its relatively high surface energy will cause a strong adhesion effect when contacting the counter material, resulting in a relatively large friction coefficient and lack of self-lubricating performance, and it is unable to form an effective lubricating film. In addition, the phenolic resin has a relatively low hardness and insufficient anti-wear ability, and is prone to abrasive wear and fatigue wear. Therefore, the tribological performance of the pure phenolic resin coating is poor.

[0087] The above are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the principle of the present invention, several improvements and refinements can still be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A phenolic resin lubricating coating, characterized in that, Components in the following mass percentages: 89% - 99% phenolic resin, 0.5% - 10% lanthanum oxide, and 0.5% - 1% additives.

2. The phenolic resin lubricating coating according to claim 1, wherein The phenolic resin lubricating coating is composed of components in the following mass percentages: 94% - 98.5% phenolic resin, 0.5% - 5% lanthanum oxide, and 1% additives.

3. The phenolic resin lubricating coating according to claim 2, wherein The phenolic resin lubricating coating is composed of components in the following mass percentages: 98.5% phenolic resin, 0.5% lanthanum oxide, and 1% additives.

4. The phenolic resin lubricating coating according to claim 2, characterized in that, The phenolic resin lubricating coating is composed of components in the following mass percentages: 94% phenolic resin, 5% lanthanum oxide, and 1% additives.

5. The phenolic resin lubricating coating according to claim 1, characterized in that, The phenolic resin lubricating coating is composed of components in the following mass percentages: 89% phenolic resin, 10% lanthanum oxide, and 1% additives.

6. The phenolic resin lubricating coating according to any one of claims 1 to 5, characterized in that The particle size of the lanthanum oxide is 1 - 30 μm.

7. The phenolic resin lubricating coating according to claim 1, wherein The additives include a defoaming agent and a leveling agent. The mass ratio of the defoaming agent to the leveling agent in the additives is 0:10 - 10:0, and the masses of both the defoaming agent and the leveling agent are not zero.

8. The phenolic resin lubricating coating according to claim 7, wherein The mass ratio of the defoaming agent to the leveling agent in the additives is 1:

1.

9. The preparation method of the phenolic resin lubricating coating according to any one of claims 1 to 8, characterized in that, It includes the following steps: Mix and grind phenolic resin, lanthanum oxide, and additives to obtain a phenolic resin composite material. Mix the phenolic resin composite material with an organic solvent to obtain a phenolic resin composite coating. Coat the phenolic resin composite coating on the surface of a preheated substrate to obtain the phenolic resin lubricating coating.

10. The preparation method according to claim 9, characterized in that, The heat treatment process of the preheated substrate includes: starting from 60°C, heating to 140°C at a heating rate of 15 - 25°C / min, holding for 1 - 2 h, and then naturally cooling to room temperature.

Images