Solid-liquid composite lubricating coating, preparation method and application

A kind of solid-liquid composite lubricating coating, preparation method and application technical field

The present invention belongs to the field of lubricating materials, relates to a kind of stamping process lubricating material technology, be specifically related to a kind of solid-liquid composite lubricating coating, preparation method and purposes, prepare a kind of solid used for secondary aluminum alloy forming by the inventive method -Liquid compound lubricating coating, the lubricating film is pre-coated on both sides of the aluminum alloy plate, providing lubrication during stamping, and can effectively protect the surface of the plate and the mold, improve the surface quality of the formed part, reduce the stamping force and Mold wear.

Background technique

[0002] Aluminum alloy has become the second largest metal material for industrial applications because of its low density, high strength, corrosion resistance, and good processability. Since aluminum has a high recovery rate and the production cost of recycled aluminum is much lower than that of electrolytic aluminum, recycled aluminum has gradually become an important choice for stamping parts in the automotive industry. However, due to the complex sources of aluminum waste recycling, the immature recycling process, and the many inherent defects caused by impurities, the performance of recycled aluminum sheets is unstable, especially the poor plasticity of thin sheets, which makes it difficult to repeatedly apply to deformed alloys. During stamping, the impurity phase defects and hole defects on the surface will affect the forming quality. Therefore, it is of great significance to improve the stamping application performance of recycled aluminum by developing a special lubrication process for recycled aluminum.

[0003] Regenerated aluminum alloys are different from primary aluminum alloys because they have more defects on their surface, and the extra abrasive wear caused by impurity phase particles falling off and the lubrication failure caused by hole defects are prone to occur during the stamping process. At present, the most widely used lubrication method in aluminum alloy stamping forming is oil lubrication. Lubricating oil plays the role of lubrication, cooling and rust prevention. However, when the lubricating oil is not selected properly, it is prone to lubrication failure, which will cause the workpiece to break or cause surface defects such as scratches on the surface of the workpiece. Moreover, lubricating oil is easy to oxidize and volatilize, and the oil film is easy to be damaged under high load, and the service temperature is limited. In addition, defects on the surface of recycled aluminum will also lead to uneven oil film thickness and load, and unstable lubrication. At the same time, solid lubrication can not only reduce the forming force of aluminum alloy sheets, reduce defects, improve the finish of stamping parts, prolong the service life of molds, but also avoid pollution and failure caused by volatilization of lubricating oil. However, the solid lubricating film has problems such as poor dispersion of the lubricating medium and difficulty in removing it after processing.

[0004] At present, in the relevant research on the lubrication of aluminum alloy sheets, there is a lack of special lubrication methods for recycled aluminum sheets developed for the specific surface defects of recycled aluminum alloys. For example, CN111334305A and CN111334300A disclose solid-liquid lubricants based on nano-graphene and silicon dioxide reinforced metal molding and preparation methods thereof. Although the lubricants can provide good lubricating performance, the preparation process is relatively complicated, and the cost of nanoparticles is too high. High, not suitable for large-scale production. At the same time, the liquid-based lubrication system is affected by defects when applied to recycled aluminum stamping, and the effect is poor. The lubricating films disclosed by CN109054951A and CN109079420A are simple to prepare, evenly dispersed in the lubricating medium, and have good corrosion resistance, weather resistance and formability, but the film layer itself has insufficient bearing capacity, and the surface defects of recycled aluminum will affect the actual Effect.

Contents of the invention

Summary of the invention The object of the present invention is to solve the deficiencies in the stamping lubrication technology of recycled aluminum alloy sheets, a kind of solid-liquid composite lubricating coating, preparation method and purposes are provided, coating of the present invention can realize solid-liquid composite lubrication coating under high load Liquid compound lubrication provides good lubrication performance, easy to clean after processing, and can protect the surface of the plate and mold and improve the forming quality.

Technical scheme of the present invention can be realized by following technical measures:

The present invention provides a kind of solid-liquid composite lubricating coating, its raw material comprises oil-containing glass microsphere, lubricating performance imparts

agent, lubricant binder, wetting and dispersing agent used to improve the dispersibility of the lubricating performance imparting agent, and an antifoaming agent used to reduce excessive air bubbles in the fluid during stirring. The lubricant binder is used as a lubricant imparting agent Elastic organic coatings with adhesive binders.

The invention provides a kind of preparation method of solid-liquid composite lubricating coating, is characterized in that, comprises the following steps:

Step 1, oil-containing glass microspheres, lubricity imparting agent and wetting and dispersing agent are joined in the lubricant binder, Add diluent, mix by mechanical agitation mode, add defoamer after mixing and leave standstill , so that the oil-containing glass microspheres and the lubricating agent are fully and uniformly dispersed to obtain a precursor fluid;

[0010] Step 2, spraying or brushing the precursor fluid obtained in step 1 on the surface of the material to be lubricated, after the surface is dry, solidified at 40°C, 000°C for 400h to form a solid-liquid composite lubricating coating.

As a kind of optimal technical scheme, the parts by weight of described oil-containing glass microsphere, lubricity imparting agent, lubricant binder and wetting and dispersing agent are respectively 2010 parts, 5-10 parts, 78-93 parts , 0.202 copies.

[0012] As a preferred technical solution, the oil-containing glass microspheres are made of hollow glass microspheres soaked in base oil.

Further preferably, the average particle diameter of described oily glass microspheres is 10050um.

Further preferably, base oil contained in the described oil-containing glass microsphere is one or more in mineral oil, polyalpha olefin, ester oil and silicone oil.

[0015] Further preferably, the base oil can be added extreme pressure antiwear agent, anti-friction agent, additives such as antioxidants.

[0016] As a preferred technical solution, the lubricity-imparting agent is selected from any one or more of polytetrafluoroethylene particles, aluminum disulfide particles, polyimide particles and high molecular weight polyethylene particles.

Further preferably, the average particle diameter of described lubricity imparting agent is 0.5~3um.

[0018] As a preferred technical solution, the defoamer is a solvent-based defoamer, and the addition is 0.4~1wt% of the solid film component.

Further preferably, described defoamer is the antifoam, defoamer of modified polysilicon or modified polysiloxane or both mixtures.

Further preferably, described defoamer is selected from any one of Defom 5400, Defom 5500, and Defom 0500 produced by Haiming Stacy Company.

[0021] As a preferred technical solution, the organic elastic coating is any one of elastic polyurethane, polyester resin, styrene-butadiene-styrene block copolymer and butyral resin.

[0022] Further preferably, the elongation at break of the resin formed by the organic elastic coating is more than 300%.

As a kind of preferred technical scheme, described dispersant is any one or more in titanate coupling agent, aluminate coupling agent, silane coupling agent and macromolecule acid; According to dispersant The method of use itself can be blended in advance or mixed with resin.

[0024] As a preferred technical solution, the thinner is a topcoat thinner, and the ratio of the amount of the thinner to the total mass of the solid-liquid composite lubricating coating is 0.001.1:1.

[0025] As a preferred technical solution, the surface of the lubricating material is coated after degreasing, and the thickness of the solid-liquid composite lubricating coating formed is 200-200um, and the coating thickness is greater than the average particle size of the oil-containing glass beads.

[0026] Further preferably, the thickness of the solid-liquid composite lubricating coating is 2-10 times the average diameter of the oily glass beads.

[0027] The present invention also protects a solid-liquid composite lubricating coating, which is prepared by the above-mentioned preparation method.

[0028] The above-mentioned precursor fluid is applied to the regenerated aluminum alloy plate after degreasing to form a stamping lubricant layer, which is used for the stamping and forming process of the regenerated aluminum alloy plate.

Core invention point of the present invention is to add oily glass microspheres, and its principle of action is: oily glass microspheres are damaged and release lubricating oil in coating friction process, form solid-liquid composite lubrication with solid lubricant, as As shown in Figure 1; the glass microspheres have high hardness, which can enhance the anti-wear performance, and at the same time, they are brittle and easy to break, and they can be broken to protect the energy absorption, so that the aluminum alloy body will not be damaged during the stamping process. After being damaged, the contained base oil can be released to provide a good lubricating environment again, which can effectively prevent the lubricating film from being washed away from the aluminum alloy body during the stamping process, causing friction damage to the aluminum alloy body, and provides stamping processing with two-stage lubrication. The continuous lubrication interface makes it possible to increase the stamping speed under the condition of obtaining a good surface shape of the workpiece, and reduce the probability of defective workpieces.

[0030] The solid-liquid composite lubricating film obtained in the present invention can also meet the conditions of high-load stamping processing, with sufficient lubricating properties and protection of recycled aluminum alloy plates. It can adapt to the stamping forming process under a large forming force and form a good protection for the aluminum alloy sheet itself.

Compared with prior art, the present invention has following beneficial effect:

(1) Excellent wear resistance, capable of withstanding relatively large stamping force, effectively reducing the influence of surface defects of the recycled aluminum alloy on the contact surface of the mold during the forming process.

(2) lubricating coating coating process is simple and convenient, and coating quality is stable.

[0034] (3) The surface of the aluminum alloy plate has excellent protection ability, and the formed part has a higher surface quality.

(4) solid lubricating film is easy to remove, and residue is few.

Description of drawings

Fig. 1 is the breakage situation of coating oily glass microsphere in tribology test.

Fig. 2 is particle distribution situation in embodiment oily glass microsphere form and coating, a is oily glass microsphere SEM figure among Fig. 2, b is solid-liquid composite lubricating coating SEM among the embodiment 2 picture.

[0038] Fig. 3 is a schematic diagram of the size of the punching cup mold in the embodiment.

Fig. 4 is the coefficient of friction-time curve of embodiment 2 and comparative example 2.

Fig. 5 is embodiment 2 and comparative example 2 coating damage contrast figure, a among Fig. 5 is the SEM figure of solid-liquid composite lubricating coating damage state in embodiment 2, b is in comparative example 2 among Fig. 5 SEM image of the damage condition of the lubricating coating.

detailed description

[0041] Before the description, it should be understood that the embodiments described in the present invention are only used to illustrate and explain the present invention and not to limit the scope of the present invention. All deformations that can be directly derived or associated by those skilled in the art from the content disclosed in the present invention should be considered as the protection scope of the present invention.

Embodiment:

Embodiments of the present invention provide a kind of preparation of the solid-liquid composite lubricating coating that contains polyalphaolefin base oil glass microsphere and polytetrafluoroethylene (PTFE) in polyvinyl butyral (PVB) to form Method and performance test, comprise the following steps: [0044] Coating preparation:

1, coating surface pre-treatment: 5052 recycled aluminum alloy plates are degreased, washed and dried (surface roughness 0.15um).

2, the preparation of oily glass microspheres: select the hollow glass microspheres of average particle diameter 30um for use, soak in vacuum environment

PAO40 base oil was used for 24 hours to prepare oil-containing glass microspheres.

3, coating film preparation: select polyvinyl butyral resin as coating binder for use, and ethanol is as diluent. Add oil-containing glass beads, silane coupling agent, polytetrafluoroethylene ultrafine powder (average particle size 2.8um, density 0.45g/cm³), by mechanical

Stir 1h, be prepared into the PVB coating that contains glass microsphere and PTFE. Add Defom 0500 (0.5wt%) as a defoamer, and brush it on the surface of the aluminum alloy substrate after standing still. After the surface is dry, cure it at 00°C for 4 hours to form a solid transparent coating film.

Coating performance test

1, dispersion state characterization: observe oily glass microsphere form, oily glass microsphere and

PTFE has a dispersion effect in the coating. The oil-containing glass beads (Fig. 2a) and the microscopic morphology of the coating in Example 2 (Fig. 2b) were observed by scanning electron microscopy. The average diameter of the oil-containing glass beads was about 30 μld, and there was a certain aggregation phenomenon between the beads. Oil-containing glass microspheres and PTFE particles are dispersed in the PVB coating with good dispersion effect and no serious agglomeration phenomenon occurs.

2, tribology test: adopt UMT-2 friction and wear testing machine, friction pair is the GCr15 bearing steel ball of diameter 4mm, carries out the linear reciprocating friction motion of pressure 2N, stroke 5mm, frequency 4Hz, test time 20min. Comparing the time required for different coatings to destroy, the longer the time required for coating destruction, the stronger the coating's bearing capacity and anti-wear performance.

3, cup punching test: adopt GBW-50 type microcomputer control punching cup test machine, the die sheet size as shown in Figure 3. The punching speed value is set to 20mrn/inin, and the blank holder force is set to 30kN. The aluminum alloy sheet enters the die under the action of the punch of the punching cup testing machine, and gradually forms a cylindrical cup shape. The Micromeasure2 white light confocal three-dimensional topography instrument produced by French STIL company scans the area of 1mm×1mm area to compare the surface roughness of the formed part, and the low surface roughness indicates that the lubrication effect is excellent.

Form embodiment 1 to embodiment 0 by changing the content of oil-containing glass microspheres and lubricity imparting agent in solid-liquid composite lubricating coating, each embodiment component content is as shown in table 1:

<td colspan="3">Each embodiment of table 1 oily glass microsphere and PTFE content</td>

<td></td><td>Oily Glass Beads</td><td>PTFE</td>

<td>Example 1</td><td>2%</td><td>5%</td>

<td>Example 2</td><td>2%</td><td>10%</td>

<td>Embodiment 3</td><td>5%</td><td>5%</td>

<td>Example 4</td><td>5%</td><td>10%</td>

<td>Example 5</td><td>10%</td><td>5%</td>

<td>Example 6</td><td>10%</td><td>10%</td>

<td>Comparative example:</td><td></td><td></td>

<td colspan="2">Comparative example 1 is commercially available QH-7 aluminum alloy stamping oil (flash point: 185 °C; Viscosity grade:</td><td>: 150; 40 °C kinematic viscosity:</td>

33035cst), QH-7 stamping oil should be brushed before the cup punching test.

[0057] Comparative examples 2 and 3 are solid lubricating films without oil-containing glass beads. The preparation method of the lubricating film is the same as that in the examples, and the contents of the components in each comparative example are shown in Table 2:

Each comparative example oily glass microsphere of table 2 and PTFE content

<td></td><td>Oily Glass Beads</td><td>PTFE</td>

<td>Comparative example 2</td><td>0%</td><td>5%</td>

<td>Comparative example 3</td><td>0%</td><td>10%</td>

Result of the test:

CN 115558539 A Instructions

[0061] In the tribological test, the violent fluctuation of the coefficient of friction marks the damage of the coating, as shown in Figure 4, the time from the beginning of friction to the violent fluctuation of the coefficient of friction is the coating damage time. Since Comparative Example 1 does not belong to the coating, no tribological test comparison was performed. The results of the time required for the coating to be destroyed in the tribological test are as shown in Table 3. The time required for the coating to be destroyed in each embodiment is significantly greater than that of the comparative examples. Example coating has good anti-wear properties. The damage of the solid-liquid composite lubricating coating in Example 4 (Fig. 5a) and the solid-liquid composite lubricating coating in Comparative Example 2 (Fig. 5b) were observed by scanning electron microscopy. The results are shown in Fig. 5. Small, there is no warping at the damaged part, the glass beads at the pressure part have been damaged and released lubricating oil, the recycled aluminum alloy plate at the bottom is less worn, and there is no obvious plastic deformation.

The required time for table 3 tribology test coating destruction

<td colspan="2">Time public</td>

<td>Example 1</td><td>332</td>

<td>Example 2</td><td>304</td>

<td>Example 3</td><td>810</td>

<td>Embodiment 4</td><td>760</td>

<td>Example 5</td><td>632</td>

<td>Example 6</td><td>348</td>

<td>Comparative example 2</td><td>170</td>

<td>Comparative example 3</td><td>70</td>

By punching cup test formed part, carry out taking pictures and observe, each embodiment surface damage is less, and quality is better than comparative example 0. Punch cup test formed part surface roughness comparison result is as shown in table 4, except oily glass beads and Except for Example 0 with high PTFE content, the surface roughness of other recycled aluminum alloy formed parts pre-coated with solid-liquid composite lubricating film is lower than that of the plate covered with only PTFE coating. Compared with QH-7 aluminum alloy stamping oil, the surface roughness of the formed parts can be reduced by up to 90%, and the lubricating effect is far superior to that of stamping oil.

The surface roughness of table 4 punching cup test formed part

<td></td><td>Ra/μη;</td><td>Rz/μητ</td>

<td>Example 1</td><td>0.52</td><td>2.98</td>

<td>Example 2</td><td>0.60</td><td>3.14</td>

<td>Example 3</td><td>0.41</td><td>2.54</td>

<td>Example 4</td><td>0.24</td><td>1.43</td>

<td>...Mg-Example 5</td><td>0.34</td><td>1.89</td>

<td>Example 6</td><td>0.77</td><td>3.67</td>

<td>Comparative example 1</td><td>2.52</td><td>13.28</td>

<td>Comparative example 2</td><td>1.00</td><td>3.97</td>

<td>Comparative example 3</td><td>0.65</td><td>3.38</td>

[0067] As can be seen from the tribology test and cup test results, the ideal coating component content can be obtained as Example 3, Example 4 and Example 5. The coating film prepared under the condition of a certain proportion of each component has the advantages of strong bearing performance, strong anti-wear performance and good lubricating effect.

[0068] The above embodiments are only used to illustrate the present invention, rather than to limit the present invention. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art should understand that various combinations, modifications or equivalent replacements of the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention, and all should cover Within the scope of the claims of the present invention.