Wear-resistant and impact-resistant composite coating based on modified eggshell powder and preparation method thereof

Abstract

The invention discloses a wear-resistant and impact-resistant composite coating based on modified eggshell powder and a preparation method of the wear-resistant and impact-resistant composite coating. The coating is composed of film-forming resin and a composite functional filler; the composite functional filler is prepared by carrying out surface modification on pretreated egg shell powder and a ceramic function enhancing component through a silane coupling agent. The pretreatment comprises the steps of calcining at 300-400 DEG C for 15-40 minutes and processing the calcined material until the D50 median diameter is 3-25 microns. Macroscopic contrast experiments prove that the filler subjected to co-treatment of calcination, particle size control and silane coupling agent modification can effectively inhibit phase separation and maintain structural integrity under harsh processing conditions, and the surface chemical activity of the filler is remarkably improved. The obtained coating has high hardness (for example, the hardness can reach more than HV0.1 1500), strong adhesion (grade 0), good toughness (the impact resistance is greater than or equal to 50 cm) and excellent wear resistance (lt: 8 mg / 1000 revolutions).

Description

TECHNICAL FIELD

[0001] The present application relates to the field of advanced coating materials, in particular to a composite coating based on modified eggshell powder with excellent wear resistance, impact resistance and high adhesion, and a preparation method thereof, which is suitable for the surface protection of components under extreme working conditions such as aerospace, ocean engineering and heavy machinery. BACKGROUND

[0002] When high-end equipment operates under extreme conditions (such as high-frequency impact, severe wear, and high-low temperature alternation), it puts forward strict requirements for the comprehensive performance of its surface protective coating. In the prior art, high-hardness coatings (such as ceramic coatings) are often brittle and prone to cracking and peeling under impact load; while polymer coatings with excellent toughness are usually insufficient in hardness and wear resistance. This contradiction between "high hardness" and "high toughness" has become a key bottleneck restricting the development of protective coating technology. Common solutions are to add rigid fillers (such as alumina, silicon carbide) to improve hardness, or to add flexible fillers / fibers to improve toughness, but often one-sidedness prevails, and the synergistic improvement of rigidity and toughness cannot be achieved. Therefore, it is of great technical and application value to develop a new type of composite coating that can solve this contradiction from the source of the filler system.

[0003] In the present application, the high-activity porous structure modified poultry eggshell powder is preferably used, and its preparation method has been applied for invention patent (application number: 202511893784X) by the applicant. The above-mentioned eggshell powder is only used as the preferred raw material for realizing the technical scheme of the present application, and the protection scope of the present application is not limited to this specific raw material and its preparation method. SUMMARY

[0004] (I) Invention purpose In view of the deficiencies of the prior art, the present application aims to provide a wear-resistant and impact-resistant composite coating based on modified eggshell powder, which has excellent comprehensive performance and is suitable for extreme environments. Through unique filler design and interface engineering, the coating aims to synergistically improve the hardness, toughness, adhesion and wear resistance of the coating.

[0005] As one of the series of researches on the high-value utilization of the same biomass raw material-poultry eggshell powder, the core of the present application, which is different from other applications in the series (relating to low-dielectric high-thermal-conductivity epoxy packaging materials and high-performance rubber composites), is to overcome the key bottleneck of the incompatibility between "high hardness" and "high toughness" in extreme protective coatings. The specific innovation point lies in the use of pretreated eggshell powder to construct a "rigid skeleton", and through the synergy with ceramic reinforcing components and unique interface engineering, a benign dissipation mechanism of impact energy through controllable micro-debonding of the interface is realized. The technical solutions of the above series of applications are independent of each other, and together constitute a systematic protection of bio-based high-performance material technology.

[0006] (II) Technical Solution To achieve the above object, the present application adopts the following technical solution: A wear-resistant and impact-resistant composite coating based on modified eggshell powder, which is composed of a film-forming resin and a composite functional filler.

[0007] The composite functional filler is prepared by surface modification of pre-treated poultry eggshell powder and ceramic functional reinforcing components with a silane coupling agent. The pre-treatment includes calcination at 300-400℃ for 15-40 minutes to completely remove organic matter and form a stable porous structure. The D50 median diameter of the pre-treated poultry eggshell powder is 3-25 μm, preferably 5-15 μm.

[0008] The ceramic functional reinforcing components are hard ceramic powders, such as at least one of alumina, silicon carbide, silicon nitride or zirconium dioxide, with an average particle size preferably of 0.1-10 μm.

[0009] The silane coupling agent preferably includes an epoxy-containing silane coupling agent and an amino-containing silane coupling agent, with a mass ratio preferably of 5:1 to 2:1. The total amount of silane coupling agent is 1.5%-3.5% of the total weight of the composite functional filler.

[0010] Based on 100 parts by weight of the film-forming resin, the addition amount of the composite functional filler is 30-150 parts by weight. Among them, the addition amount of the pre-treated poultry eggshell powder is 20-100 parts by weight, and the addition amount of the ceramic functional reinforcing components is 10-40 parts by weight.

[0011] To further improve the performance of the coating under extreme impact, the composite coating can also selectively contain a toughening component, which can be added in an amount of 5-30 parts by weight. The toughening component can be selected from at least one of aramid fiber, polymer microneedle, carbon fiber or wollastonite whisker.

[0012] The film-forming resin is preferably at least one of epoxy resin, polyurethane resin or acrylic resin.

[0013] (III) Beneficial Effects Compared with the prior art, the technical solution provided by the present application has the following beneficial effects: 1. Excellent performance synergy: The composite coating provided by the present application is characterized by using poultry eggshell powder treated by a specific pretreatment to replace traditional fillers, and through the synergistic effect of ceramic functional reinforcing components and silane coupling agents, the coating has high hardness (e.g. HV0.1 1500 or more), good impact resistance (≥50 cm), excellent adhesion (0 level) and outstanding wear resistance (<8 mg / 1000 turns).

[0014] 2. Interface bonding firmness: the unique pretreated eggshell powder has a high active surface and porous structure, forms firm chemical bonding and mechanical interlocking with silane coupling agent and resin matrix, and significantly improves the service reliability in extreme environments.

[0015] 3. Strong scalability: based on the verified 'eggshell powder-ceramic' binary rigid-tough synergistic system, the skilled person in the art can perform directional optimization of toughness according to needs, for example by selectively introducing toughening components (such as aramid fiber, polymer microneedle, whisker, etc.). This provides a clear and flexible technical path for product serialization customization based on the same high-performance core system for different sub-working conditions. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 : shows the complete preparation process of the wear-resistant and impact-resistant composite coating based on modified eggshell powder of the present application.

[0017] Figure 2 : comparison photos of the reaction phenomena of pretreated poultry eggshell powder (left) and chemically pure calcium carbonate (right) in acetic acid solution.

[0018] Figure 3 : state photos of the present application coating sample after impact test (left) and crosshatch adhesion test (right).

[0019] Figure 4 : comparison photos of the macroscopic state of the present application coating (left), comparative example 1 calcium carbonate coating (middle), and comparative example 2 blank resin coating (right) after extreme impact test.

[0020] Figure 5 : comparison photos of the state of all repeat test samples (front row: present application coating group; back row left: comparative example 1 group; back row right: comparative example 2 group).

[0021] Figure 6 : snapshot photos of the state of the limit impact test. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be further described in detail below in conjunction with examples. It should be understood that the following examples are only used to explain the present application, and do not limit the protection scope of the present application. Unless otherwise specified, the "parts" described below refer to "weight parts".

[0023] Example 1: Preparation of composite functional filler 1. Pretreatment of poultry eggshell powder (uniform preparation method of core raw material of the present application): (1) Cleaning and removing impurities: wash the poultry eggshell raw material with clean water to remove residual egg white, egg yolk and visible organic impurities.

[0024] (2) Preliminary drying: The washed wet material is dried at 110°C under air flow until the moisture content is less than 2%.

[0025] (3) Calcination activation: The dried powder is placed in a muffle furnace and calcined at 350°C for 25 minutes in an air atmosphere.

[0026] (4) Grinding and grading: After mechanical grinding, the calcined and cooled material is subjected to particle size control to ensure that the D50 median diameter of the resulting activated poultry eggshell powder is about 10 μm (i.e., falls within the preferred range of 5-15 μm).

[0027] 2. Filler compounding and surface modification: a. 60 parts of the above-mentioned pretreated poultry eggshell powder and 15 parts of aluminum oxide powder with an average particle size of 1 μm are weighed and placed in a container and mixed uniformly.

[0028] b. 1.5 parts (about 2.0% of the total mass of the above-mentioned mixed filler) of a silane coupling agent (γ-(2,3-epoxypropoxy) propyltrimethoxysilane (KH-560) and γ-aminopropyltriethoxysilane (KH-550) compounded at a mass ratio of 3:1) is added to a mixed solvent of ethanol and deionized water (ethanol:water volume ratio = 9:1), and stirred at room temperature to hydrolyze it thoroughly.

[0029] c. The above-mentioned hydrolysis solution is uniformly added to the mixed filler of step a under stirring to ensure that all filler particles are fully infiltrated.

[0030] d. The wet material is dried at 50-60°C to loosen, then transferred to an air drying oven and dried at 105-120°C for 0.5-3 hours to completely remove residual moisture and complete the coupling reaction. After cooling, the material is discharged, and the composite functional filler (denoted as filler C-1) is obtained.

[0031] Note: The above preparation is the core composite functional filler of the present application. It should be noted that the present application provides a high-performance filler basic system. Those skilled in the art know that when the coating application has more extreme requirements for crack resistance and impact resistance, toughening materials such as aramid short fibers, polymer microneedles, and wollastonite whiskers can be introduced based on the core filler of the present application through conventional compounding techniques, and the specific type and amount can be optimized through conventional mechanical property tests in the art. This extended application is based on the strong interfacial bonding provided by the present application.

[0032] Example 2: Comparative demonstration of filler surface chemical activity To reveal the surface properties of the pretreated poultry eggshell powder of the present application, comparative experiments were conducted: 10 grams of the pretreated poultry eggshell powder obtained in Example 1 and 10 grams of chemically pure calcium carbonate (Shanghai Test brand, CAS 471-34-1) were weighed, respectively, 200 milliliters of 9% edible white vinegar was added, and the room temperature was observed.

[0033] The pretreated poultry eggshell powder group immediately triggered a violent and continuous reaction (more than 4 minutes), forming a uniform light yellow suspension, which started to settle after more than 11 minutes of standing; the chemically pure calcium carbonate only produced a small amount of bubbles, the reaction stopped rapidly within tens of seconds, and most of the powder was aggregated and quickly settled due to poor wettability, and the liquid showed an uneven turbidity.

[0034] Conclusion: This experiment proves that the pretreatment process of the present application gives the eggshell powder a surface chemical reaction activity, liquid wettability, and a developed through-porous structure far superior to ordinary calcium carbonate.

[0035] Example 3: Composite coating preparation and performance testing (binary system) 1. Slurry preparation: 100 parts of bisphenol A type epoxy resin (E-51) were weighed, and 75 parts of the composite functional filler prepared in Example 1 (prepared by surface modification of 60 parts of pretreated poultry eggshell powder and 15 parts of aluminum oxide powder) were added under the condition of 50-70℃ heat preservation. A handheld electric mixer was used to continuously stir the mixture at medium-high speed for 15-25 minutes until it was uniformly dispersed.

[0036] 2. Curing and coating: The above slurry was cooled to 35-45℃. 50 parts of polyamide 651 curing agent were added, and after stirring and mixing uniformly, it was left to mature. The mixed slurry was coated on a sandblasted steel plate of 150mm x 70mm x 0.8mm, and the wet film thickness was controlled at about 200μm.

[0037] 3. Stepwise temperature rising curing: The sample plate was placed in an oven, and the curing program was executed: from room temperature to 80℃ for 1 hour, then to 120℃ for 2 hours. After the program ended, the oven was cooled to room temperature.

[0038] 4. Performance testing: The cured coating sample was tested, and the results were as follows: Adhesion: 0 level (GB / T 9286).

[0039] Impact resistance: 55 cm (GB / T 1732).

[0040] Vickers hardness: HV 1520 (GB / T 4340.1).

[0041] Taber abrasion: 7.5 mg / 1000 turns (CS-10 wheel, 1000g load, ASTM D4060).

[0042] Effect analysis: the above data show that the core system of the application has achieved an excellent balance of high hardness and high toughness. Based on this strong interfacial bonding, the introduction of toughening components to further improve toughness is a routine technical extension that can be foreseen and realized by those skilled in the art.

[0043] Comparative Example 1: Calcium carbonate control experiment Except that the "pretreated poultry eggshell powder" in Examples 1 and 3 is replaced by "chemically pure calcium carbonate" in terms of quality, all other conditions are exactly the same as Examples 1 and 3.

[0044] The performance test results of the obtained coating are: adhesion 1-2 grade, impact resistance 30 cm, Vickers hardness HV 980, Taber wear 15.8 mg / 1000 turns.

[0045] Comparative Example 2: Blank resin control experiment Without adding any filler, 100 parts of bisphenol A type epoxy resin (E-51) is directly mixed with 50 parts of polyamide 651 curing agent, and the coating and curing process is the same as Example 3.

[0046] The performance test results of the obtained coating are: adhesion 1 grade, impact resistance >60 cm, Vickers hardness HV 110, Taber wear >50 mg / 1000 turns.

[0047] Effect summary: comparing Example 3 with Comparative Examples 1 and 2, using the eggshell powder pretreated according to the application, compared with ordinary calcium carbonate, the hardness, adhesion, impact resistance and wear resistance of the coating are all significantly and synergistically improved, and the "rigidity and toughness contradiction" is perfectly balanced, and the effect is far superior to that of conventional fillers.

[0048] The above-described examples are only the preferred specific embodiments of the present application, but the protection scope of the present application is not limited thereto. Any changes or replacements within the technical scope disclosed by the present application can be easily thought of by those skilled in the art, and should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A wear-resistant and impact-resistant composite coating based on modified eggshell powder, characterized in that, It is composed of a film-forming resin and a composite functional filler; the composite functional filler is prepared by mixing pretreated poultry eggshell powder with a ceramic functional reinforcing component and then surface-modifying it with a silane coupling agent; the median D50 diameter of the pretreated poultry eggshell powder is 3-25 μm, and its BET specific surface area is >5 m² / g and its surface water contact angle is >90°; based on 100 parts by weight of film-forming resin, the amount of composite functional filler added is 30-150 parts by weight, of which the pretreated poultry eggshell powder is 20-100 parts by weight and the ceramic functional reinforcing component is 10-40 parts by weight.

2. The composite coating according to claim 1, characterized in that, The median D50 diameter of the pretreated poultry eggshell powder is 5-15 μm.

3. The composite coating according to claim 1, characterized in that, The ceramic functional enhancement component is at least one of alumina, silicon carbide, silicon nitride, or zirconium dioxide.

4. The composite coating according to claim 3, characterized in that, The average particle size of the ceramic functional enhancement component is 0.1-10 μm.

5. The composite coating according to claim 1 or 2, characterized in that, The silane coupling agent comprises an epoxy-containing silane coupling agent and an amino-containing silane coupling agent, with a mass ratio of 5:1 to 2:

1. The total amount of the silane coupling agent is 1.5%-3.5% of the total weight of the composite functional filler.

6. The composite coating according to any one of claims 1-5, characterized in that, The composite coating may also contain 5-30 parts by weight of toughening components.

7. The composite coating according to claim 6, characterized in that, The toughening component is a fibrous or needle-like material selected from at least one of aramid fibers, polymer microneedles, carbon fibers, or wollastonite whiskers.

8. A method for preparing a composite coating as described in any one of claims 1-7, characterized in that, Includes the following steps: (1) Preparation of composite functional filler: After mixing the pretreated poultry eggshell powder, ceramic functional reinforcing components, and toughening components added when necessary, the surface is modified by using a silane coupling agent. (2) The composite functional filler obtained in step (1) and the film-forming resin are stirred and dispersed under heating conditions for 15-30 minutes to obtain a uniform slurry; (3) After the slurry has cooled, add the curing agent, mix well and let it stand to mature; (4) The mixed slurry is coated onto the surface of the pretreated substrate and cured by programmed temperature rise to obtain the coating.

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