Wood-based friction material with life self-monitoring function and preparation method thereof

Abstract

The application relates to the technical field of processing and preparation of wood-based functional materials, and particularly discloses a wood-based friction material with a service life self-monitoring function and a preparation method thereof, which comprises the following steps: dispersing poplar powder in a co-solvent formed by mixing choline chloride and dihydroxide oxalic acid to obtain a mixed liquid, diluting and washing with water to obtain filter residue A; dispersing the filter residue A in distilled water I, adding sodium chlorite and acetic acid, stirring, and washing with water to obtain filter residue B; dispersing the filter residue B in distilled water II, adding phenolphthalein, and crushing to obtain a dispersion liquid; adding sodium chloride, solid Tris and tannic acid into the dispersion liquid, stirring, and washing with water to obtain filter residue C; dispersing the filter residue C in distilled water III, adding polyvinyl alcohol, stirring, pouring into a mold, and drying; dispersing the filter residue A in distilled water, adding sodium hydroxide and polyvinyl alcohol, stirring to obtain a mixed base liquid, continuously pouring into the mold, and drying to obtain the wood-based friction material. The friction material has the service life self-monitoring function, and the method is simple and low in cost.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of processing and preparation of wood-based functional materials, and particularly relates to a wood-based friction material with a service life self-monitoring function and a preparation method thereof. BACKGROUND

[0002] The wear resistance of a material is related to the service life of the material, and thus the wear resistance becomes a key factor for selecting a material as a moving part of a structural material or a functional material. The wear resistance of a material is related to aerospace, national defense and military industry, and even to the movement of vehicles and the wearing of shoes and socks. For the research on the performance of a material, especially for metal-based friction materials, paper-based friction materials, resin-based friction materials and functional self-lubricating wear-resistant materials, the materials are usually consumed quickly during use, and thus a large number of samples need to be repeatedly subjected to wear experiments to estimate the service life of the materials, so as to avoid safety problems. However, it is difficult to timely find and detect the aging of the materials during the specific use of the materials, and thus there are certain safety problems and a large detection cost.

[0003] In order to timely find and detect the aging of a material during use of the material and avoid certain safety problems, it is necessary to develop a friction material capable of realizing functional service life self-monitoring. However, up to now, no friction material can realize functional service life self-monitoring, and the technical achievements in this field are still in short supply.

[0004] Compared with other friction materials, wood-based friction materials are more widely used. Therefore, it is necessary to provide a wood-based friction material capable of realizing functional service life self-monitoring and a preparation method thereof. SUMMARY

[0005] In view of the deficiencies in the prior art, the purpose of the present application is to provide a wood-based friction material with a service life self-monitoring function, which can monitor the service life of the friction material, and has a simple and easy-to-operate preparation process and a low cost, and a preparation method thereof.

[0006] In order to achieve the above-mentioned purpose, the following technical solutions are adopted in the present application:

[0007] The preparation method of the wood-based friction material with a service life self-monitoring function comprises the following steps:

[0008] Step 1: taking poplar powder as a raw material, dispersing the poplar powder in a co-solvent formed by mixing and heating chlorocholine chloride and dihydrate oxalic acid, heating to 100-120 DEG C, continuously stirring until the poplar powder is dissolved to obtain a mixed liquid, adding distilled water to the mixed liquid to dilute and performing multiple water washing to obtain filter residue A;

[0009] The ratio of the volume of the co-solvent to the mass of the poplar powder is 300 mL:(3.5-4.5 g).

[0010] Step 2: dispersing the filter residue A obtained in step 1 in distilled water I, adding sodium chlorite and acetic acid, and then performing filtration and water washing to obtain filter residue B; dispersing the filter residue B in distilled water II, and then adding phenolphthalein and performing mechanical crushing treatment to obtain a dispersion liquid;

[0011] The volume of the distilled water I, the mass of the sodium chlorite, the volume of the acetic acid, the volume of the distilled water II, and the mass of the phenolphthalein are in the ratio of 300 mL:(4.5-8.5 g):(3.0-6.0 mL):(300-400 mL):(0.45-0.85 g).

[0012] Step 3: adding sodium chloride, solid Tris, and tannic acid to the dispersion liquid, continuously stirring for 2-4 h, and then performing multiple filtration and water washing to obtain filter residue C; dispersing the filter residue C in distilled water III, adding polyvinyl alcohol, and continuously stirring at 100°C for 2-4 h; pouring the mixed liquid into a mold, and then drying at 45°C;

[0013] The volume of the dispersion liquid, the mass of the sodium chloride, the mass of the solid Tris, the mass of the tannic acid, the volume of the distilled water III, and the mass of the polyvinyl alcohol are in the ratio of (300-400 mL):(4.5-8.5 g):(2.25-4.25 g):(4.5-8.5 g):(300-400 mL):(2.25-4.25 g).

[0014] Step 4: dispersing the filter residue A obtained in step 1 in distilled water, adding sodium hydroxide and polyvinyl alcohol, and continuously stirring at 100°C for 2-4 h to obtain a mixed base liquid; continuously pouring the mixed base liquid into the mold used in step 3, and then drying at 45°C to finally obtain a wood-based friction material.

[0015] The volume of the distilled water, the mass of the sodium hydroxide, and the mass of the polyvinyl alcohol are in the ratio of (300-400 mL):(4.5-8.5 g):(2.25-4.25 g).

[0016] Further, the number of filtration and water washing in step 1 is 3-5 times.

[0017] Further, the stirring time in step 1 is 3-5 h.

[0018] Further, the number of filtration and water washing in step 2 is 3-5 times.

[0019] Further, the mechanical crushing treatment time in step 2 is 40-80 min.

[0020] Further, the drying time in step 3 is 4 h.

[0021] Further, the drying time in step 4 is 12h.

[0022] A wood-based friction material with a service life self-monitoring function is prepared by the preparation method

[0023] Compared with the prior art, the present application has the following technical effects:

[0024] In the present application, the preparation method specifically comprises the following steps: heating and stirring poplar powder, choline chloride and oxalic acid dihydrate, adding distilled water to dilute and filter and washing after complete dissolution to obtain filter residue A; dispersing the filter residue A in distilled water, adding sodium chlorite and acetic acid, filtering and washing after heating and stirring to obtain filter residue B; dispersing the filter residue B in distilled water, adding a specific amount of phenolphthalein, and performing mechanical crushing treatment to obtain a dispersion liquid; heating, washing and dispersing the dispersion liquid, sodium chloride, solid Tris and tannic acid in distilled water, and then adding polyvinyl alcohol, followed by heating, stirring, pouring into a mold and drying; high-temperature stirring the filter residue A, sodium hydroxide and polyvinyl alcohol, and then pouring into a mold and drying to obtain the wood-based friction material. The preparation method is very simple, and the raw materials used in the whole preparation process are stable and economical and practical, most of which have stable performance and simple operation.

[0025] The wood-based friction material prepared by the present application has a dense layered structure, and the layered structures are tightly crosslinked, and has the advantages of high toughness, good tensile property, wear resistance, high mechanical strength, strong corrosion resistance, stable chemical property and the like. However, the greatest feature is that it has a service life self-monitoring function, so that when the service life ends, the sodium hydroxide is exposed due to structural damage, reacts with phenolphthalein to turn red, and obvious color change is generated, so that the aging and scrapping of the friction material can be perceived at the first time, and this process can be completed without any external substances, which is fast, convenient and accurate, and the scrapped material can be replaced in time to avoid safety hazards.

[0026] Moreover, the raw material poplar powder used in the present application is a natural biomass green material, which has the characteristics of green environmental protection, rich reserves, low energy consumption, less pollution, wide material sources, light weight, high strength, good elasticity, high fiber content and easy processing.

[0027] In summary, the wood-based friction material prepared by the preparation method of the present application can monitor the service life of the friction material, and the preparation process is simple, easy to operate and low in cost. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 SEM morphology of the wood-based friction material in Example 1 of the present application;

[0029] Figure 2 XRD patterns of the wood cellulose (filter residue A obtained in step 1), esterified nanocellulose and natural poplar in Example 1 of the present application;

[0030] Figure 3 Zeta potential graph of cellulose extracted in Example 1 of the present application (dispersion obtained after dispersing the residue A obtained in Step 1 in water in Step 2), (-33.7 mV), natural poplar powder (-10.3 mV), and lignocellulose (residue A obtained in Step 1) (-34.2 mV);

[0031] Figure 4 Friction coefficient graph of the lignin-based friction material in Example 1 of the present application at a sliding speed of 200 rpm and different loads (1, 3, 5 N);

[0032] Figure 5 Average friction coefficient-abraded width summary graph of the lignin-based friction material in Example 1 of the present application in the friction and wear experiment. DETAILED DESCRIPTION

[0033] The specific content of the present application is further explained in detail in connection with the following examples.

[0034] Distilled water is used for washing in the specific steps of the present application; the molding method is specifically casting molding; the wood pulp in Step 2 is broken after bleaching to milky white to facilitate observation of the color change after adding phenolphthalein; bleaching is adding sodium chlorite and acetic acid to the wood pulp; the molecular weight of polyvinyl alcohol used in each example of the present application is 145000.

[0035] The co-solvent used in Step 1 is a liquid obtained by mixing choline chloride and dihydroxy oxalic acid in equal mass and heating to melt at 110°C.

[0036] EXAMPLE

[0037] Example 1

[0038] A preparation method of a lignin-based friction material with a service life self-monitoring function, comprising the following steps:

[0039] Step 1: 300 mL of co-solvent and 3.5 g of poplar powder are mixed and continuously heated and stirred at 100°C for 3 hours, and then filtered and washed with water for 3 times to obtain residue A;

[0040] Step 2: The residue A obtained in Step 1 is dispersed in 300 ml of distilled water, 4.5 g of sodium chlorite and 3.0 ml of acetic acid are added, and after continuously heating and stirring at 95°C, it is filtered and washed with water to obtain residue B. The obtained residue B is dispersed in 300 ml of distilled water, 0.45 g of phenolphthalein is added, and then mechanically broken for 40 min to obtain a dispersion;

[0041] Step 3: Take 300 mL of the dispersion treated in step 2 and add 4.5 g of sodium chloride, 2.25 g of solid Tris, and 4.5 g of tannic acid. After stirring, filter and wash with water three times to obtain filter residue C. Disperse filter residue C in 300 ml of distilled water, add 2.25 g of polyvinyl alcohol, and stir at 100°C for 2 hours. Pour the mixture into a mold and dry at 45°C for 4 hours.

[0042] Step 4: Disperse the filter residue obtained in step 1 in 300 ml of distilled water, add 4.5 g of sodium hydroxide and 2.25 g of polyvinyl alcohol, and stir at 100°C for 2 hours. Continue pouring into the mold of step 3 and dry at 45°C for 12 hours to finally obtain a wood-based friction material.

[0043] Example 2

[0044] A method for preparing a wood-based friction material with a life self-monitoring function, comprising the following steps:

[0045] Step 1: Mix 300 mL of co-solvent and 4 g of poplar powder, and continuously heat and stir at 110°C for 4 hours. Filter and wash with water four times to obtain filter residue A.

[0046] Step 2: Disperse filter residue A obtained in step 1 in 300 ml of distilled water, add 6.0 g of sodium chlorite and 4.5 ml of acetic acid, and continuously heat and stir at 100°C. After filtering and washing with water, obtain filter residue B. Disperse filter residue B in 350 ml of distilled water, add 0.60 g of phenolphthalein, and mechanically crush for 60 min to obtain a dispersion.

[0047] Step 3: Take 350 mL of the dispersion treated in step 2 and add 6.0 g of sodium chloride, 3.25 g of solid Tris, and 6.0 g of tannic acid. After stirring, filter and wash with water four times to obtain filter residue C. Disperse filter residue C in 350 ml of distilled water, add 3.25 g of polyvinyl alcohol, and stir at 100°C for 3 hours. Pour the mixture into a mold and dry at 45°C for 4 hours.

[0048] Step 4: Disperse the filter residue obtained in step 1 in 350 ml of distilled water, add 6.0 g of sodium hydroxide and 3.25 g of polyvinyl alcohol, and stir at 100°C for 3 hours. Continue pouring into the mold of step 3 and dry at 45°C for 12 hours to finally obtain a wood-based friction material.

[0049] Example 3

[0050] A method for preparing a wood-based friction material with a life self-monitoring function, comprising the following steps:

[0051] Step 1: 300 mL of co-solvent and 4.5 g of poplar powder were mixed and continuously heated and stirred at 120°C for 5 hours, and then filtered and washed with water for 5 times to obtain filter residue A;

[0052] Step 2: The filter residue A obtained in step 1 was dispersed in 300 ml of distilled water, 8.5 g of sodium chlorite and 6.0 ml of acetic acid were added, and after continuous heating and stirring at 110°C, filtration and water washing were performed to obtain filter residue B. The filter residue B obtained was dispersed in 400 ml of distilled water, 0.85 g of phenolphthalein was added, and mechanical crushing treatment was performed for 80 min to obtain a dispersion liquid;

[0053] Step 3: 400 mL of the dispersion liquid treated by the method of step 2 was taken and 8.5 g of sodium chloride, 4.25 g of solid Tris and 8.5 g of tannic acid were added thereto, and after stirring, filtration and water washing were performed for 5 times to obtain filter residue C. The filter residue C was dispersed in 400 ml of distilled water, 4.25 g of polyvinyl alcohol was added, and stirring was performed at 100°C for 4 hours. The mixture was cast in a mold, and dried at 45°C for 4 hours;

[0054] Step 4: The filter residue obtained in step 1 was dispersed in 400 ml of distilled water, 8.5 g of sodium hydroxide and 4.25 g of polyvinyl alcohol were added, and stirring was performed at 100°C for 4 hours. The mixture was continuously cast in the mold of step 3, and dried at 45°C for 12 hours to finally obtain a wood-based friction material.

[0055] Figure 1 Figure 1 is a SEM morphology diagram of the wood-based friction material prepared, from which it can be seen that it presents a dense layered structure, and the polyvinyl alcohol is crosslinked therein, greatly improving the mechanical properties of the composite film material and promoting the load transfer between the lamellas. Figure 1

[0056] Figure 2 Figure 2 is an XRD pattern of the lignocellulose (filter residue A obtained in step 1), and esterified nanocellulose, and natural poplar in Example 1. The lignocellulose shows the presence of diffraction peaks similar to natural poplar, indicating the crystal structure of cellulose. Compared with wood, the intensity of the characteristic peaks of esterified nanocellulose and lignocellulose is reduced at 2θ = 15.3°, 20.9°, 22.9°, which is due to the decrease in detection depth caused by structure densification. In addition, hemicellulose and amorphous cellulose are dissolved and removed during the solvent treatment. The crystallinity of esterified nanocellulose and lignocellulose is basically the same, but it is lower than that of natural poplar, indicating that the crystallinity of cellulose after DES co-solvent treatment is reduced. In addition, the peaks of esterified nanocellulose and lignocellulose at 15.3° and 20.9° disappear after delignification treatment. These peaks can be attributed to the residual DES in lignin during the solvation process.

[0057] Figure 3 ​Zeta potential of natural poplar (-10.3 mV), cellulose extracted in Example 1 (dispersion obtained after dispersion of the residue A from step 1 in water in step 2) (-33.7 mV) and lignocellulose (residue A from step 1) (-34.2 mV). These negatively charged functional groups come from carbonyl and Hiebert ketone in cellulose, which give excellent dispersion stability to cellulose through mutual repulsion of charges. In NCF slurry, esterification of hydroxyl groups in cellulose carries more negative charges, resulting in lower zeta potential, which further proves that its excellent dispersion stability is related to the DES solvation process.

[0058] Figure 4 is the friction coefficient curve obtained at a sliding speed of 200 rpm and different loads (1, 3, 5 N). At a load of 5 N, the friction coefficient curve is stable and has little change.

[0059] Figure 5 is the average friction coefficient-abraded width summary chart of the friction and wear experiment. At a speed of 200 rpm, the minimum average friction coefficient is 0.065 at 1 N, and the average friction coefficients at 3 N and 5 N are 0.1521 and 0.1842, respectively. The abraded widths at 1 N, 3 N and 5 N are 234 μm, 273 μm and 396 μm, respectively, which indicates that the prepared wood-based friction material has a large surface hardness and also indicates its high wear resistance.

[0060] Although the content of the present application has been described in detail in the above examples, it should be recognized that the above description should not be considered as a limitation of the present application.

Claims

1. A method for producing a wood-based friction material having a lifetime self-monitoring function, characterized by, It comprises the following steps: Step 1: taking poplar powder as raw material, dispersing it in a co-solvent formed by mixing and heating chlorocholine chloride and dihydroxalic acid, heating to 100-120℃, continuously stirring until the poplar powder is dissolved to obtain a mixed liquid, adding distilled water to dilute and filtering and washing multiple times to obtain filter residue A; The ratio of the volume of the co-solvent to the mass of the poplar powder is 300mL:(3.5-4.5g); Step 2: dispersing the filter residue A obtained in step 1 in distilled water I, adding sodium chlorite and acetic acid, continuously heating and stirring at 95-110℃, filtering and washing to obtain filter residue B, dispersing the filter residue B in distilled water II, adding phenolphthalein, and performing mechanical crushing treatment to obtain a dispersion liquid; The ratio of the volume of the distilled water I, the mass of sodium chlorite, the volume of acetic acid, the volume of the distilled water II, and the mass of phenolphthalein is 300mL:(4.5-8.5g):(3.0-6.0mL):(300-400mL):(0.45-0.85g); Step 3: adding sodium chloride, solid Tris, and tannic acid to the dispersion liquid, continuously stirring for 2-4h, filtering and washing multiple times to obtain filter residue C, dispersing the filter residue C in distilled water III, adding polyvinyl alcohol, and continuously stirring at 100℃ for 2-4h, pouring the mixed liquid into a mold, and drying at 45℃; The ratio of the volume of the dispersion liquid, the mass of sodium chloride, the mass of solid Tris, the mass of tannic acid, the volume of the distilled water III, and the mass of polyvinyl alcohol is (300-400mL):(4.5-8.5g):(2.25-4.25g):(4.5-8.5g):(300-400mL):(2.25-4.25g); Step 4: taking the filter residue A prepared in step 1, dispersing it in distilled water, adding sodium hydroxide and polyvinyl alcohol, and continuously stirring at 100℃ for 2-4h to obtain a mixed base liquid, continuing to pour the mixed base liquid into the mold used in step 3, and drying at 45℃ to finally obtain a wood-based friction material; The ratio of the volume of the distilled water, the mass of sodium hydroxide, and the mass of polyvinyl alcohol is (300-400mL):(4.5-8.5g):(2.25-4.25g).

2. The method of claim 1, wherein the wood-based friction material having a life self-monitoring function is prepared by the steps of: (a) mixing the wood-based friction material with a plurality of metal particles; (b) applying a coating layer to the wood-based friction material; and (c) applying a plurality of metal particles to the coating layer. The number of times of filtering and washing in step 1 is 3-5 times.

3. The method of claim 1, wherein the wood-based friction material is prepared by the steps of: The stirring time in step 1 is 3-5h. ​ 4. The method of claim 1, wherein the wood-based friction material is prepared by the steps of: The number of times of filtering and washing in step 2 is 3-5 times. ​ 5. The method of claim 1, wherein the wood-based friction material having a life self-monitoring function is prepared by the steps of: (a) mixing the wood-based friction material with a plurality of metal particles; (b) applying a coating layer to the wood-based friction material; and (c) applying a plurality of metal particles to the coating layer. The mechanical crushing treatment time in step 2 is 40-80min.

6. The method of claim 1, wherein the wood-based friction material having a life self-monitoring function is prepared by the steps of: (a) mixing the wood-based friction material with a plurality of metal particles; (b) applying a coating layer to the wood-based friction material; and (c) applying a plurality of metal particles to the coating layer. The drying time in step 3 is 4h.

7. The method of claim 1, wherein the wood-based friction material having a life self-monitoring function is prepared by the steps of: (a) mixing the wood-based friction material with a plurality of metal particles; (b) applying a coating layer to the wood-based friction material; and (c) applying a plurality of metal particles to the coating layer. The drying time in step 4 is 12h.

8. A wood-based friction material having a lifetime self-monitoring function, characterized by: Prepared by the preparation method of any one of claims 1-7.

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