High-temperature-resistant ceramic-based marking coating and preparation method thereof

Abstract

The invention provides a high-temperature-resistant ceramic-based marking coating and a preparation method thereof. The coating comprises the following components in parts by weight: 20-80 parts of a solvent, 50-100 parts of ceramic powder, 10-40 parts of an inorganic sintering aid, 5-30 parts of a binder and 10-40 parts of hydrated sodium silicate. The coating can be quickly dried and pre-shaped, and can be sintered in a heat treatment process to form a colored and durable ceramic marking layer with high adhesive force, and is suitable for automatic identification, batch tracking and digital management. After being subjected to metal post-treatment processes such as high temperature, acid washing and alkali washing for a long time, the ceramic marking layer can still keep a mark complete without falling off, and has the characteristics of stability at high temperature, oxidation resistance and stripping resistance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal heat treatment process and intelligent manufacturing marking technology, and particularly discloses a high-temperature-resistant ceramic-based marking paint and a preparation method thereof. BACKGROUND

[0002] In modern industrial manufacturing processes, the application of ferrous and non-ferrous metal processing materials is increasingly widespread, and higher requirements are put forward for the marking clarity, durability and process compatibility in the heat treatment, transportation and processing processes. Traditional paints and inks are prone to falling off, discoloration or gasification in the high-temperature process, resulting in marking failure and affecting production information tracing and quality management. SUMMARY

[0003] To overcome the stability problems of traditional marking materials in high-temperature and chemical treatment, the present application provides a high-temperature-resistant ceramic-based marking paint, which is composed of a general solvent system and various ceramic powders and can be sintered and solidified synchronously with the metal material heat treatment process. The present application also provides a preparation method of the paint.

[0004] To achieve the above-mentioned purpose, the present application provides the following technical solutions.

[0005] A high-temperature-resistant ceramic-based marking paint, which comprises, by weight fraction, 20-80 parts of a solvent, 50-100 parts of ceramic powder, 10-40 parts of inorganic sintering aid, 5-30 parts of binder and 10-40 parts of hydrated sodium silicate.

[0006] Preferably, the solvent is selected from at least one of deionized water, ethanol and acetone, and water is preferably used to ensure the solubility of hydrated sodium silicate and improve the preparation convenience and high-temperature adhesion of the slurry.

[0007] Preferably, the ceramic powder is selected from at least one of alumina, zirconia, chromium oxide and cobalt aluminate spinel. The above-mentioned ceramic powder is white, green or blue, which can improve the identification of the marking paint on different substrate surfaces.

[0008] Preferably, the inorganic sintering aid is selected from at least two of magnesium oxide, calcium oxide and yttrium oxide, and more preferably a mixture of 5-20 parts of magnesium oxide and 5-20 parts of calcium oxide is used.

[0009] Preferably, the binder is a thickening gelling agent selected from at least one of carrageenan, gelatin, sodium carboxymethyl cellulose (CMC-Na) and sodium alginate. The binder can form a pattern on the surface of the substrate at room temperature.

[0010] Preferably, the hydrated sodium silicate is selected from at least one of sodium silicate pentahydrate and sodium silicate nonahydrate. The silicate acts as a curing agent in the coating, connecting ceramic powder particles during heat treatment, thereby forming a network structure at the microscale, and enabling the formed coating to have certain bonding strength. If the silicate is used in too small an amount, the above-mentioned curing and connecting effects are not obvious; if the silicate is used in too large an amount, it will lead to high sintering shrinkage, poor slurry fluidity, easy cracking during drying, and deterioration of corrosion resistance and high-temperature performance.

[0011] The application also provides a preparation method of the high-temperature-resistant ceramic-based marking coating, comprising the following steps:

[0012] (1) adding hydrated sodium silicate into a solvent to obtain a transparent solution by dissolution;

[0013] (2) adding ceramic powder and inorganic sintering aids into the solution obtained in step (1) and stirring uniformly to form a ceramic slurry;

[0014] (3) adding a binder into the ceramic slurry obtained in step (2) and stirring until fully mixed to form a pre-curable slurry with higher viscosity;

[0015] (4) coating the pre-curable slurry obtained in step (3) on the surface of a substrate material to be marked, and pre-drying to form a preliminary solidified mark;

[0016] (5) performing heat treatment on the marked substrate material to form a ceramic-based marking coating.

[0017] Preferably, in step (1), the dissolution conditions are stirring dissolution at room temperature or heating at 60°C for 20-40 minutes.

[0018] Preferably, in step (4), the pre-drying is performed by an oven, hot air, infrared or heat baking lamp, the heating temperature is 50-80°C, preferably 55°C, and the heating time is 5-10 minutes.

[0019] Preferably, in step (5), the heat treatment temperature is 500-1100°C, and the time is 1-10 hours.

[0020] The application also provides an application of the high-temperature-resistant ceramic-based marking coating. The coating is suitable for being used as a marker on the surface of various metal substrates, including heat-resistant steel, heat-treated steel, tinplate steel and its pipe, bar and plate materials, etc.

[0021] The coating can be quickly dried, preformed, and sintered in a heat treatment process to form a high-adhesion, colored, and durable ceramic marking layer suitable for automatic identification, batch tracking, and digital management. The ceramic marking layer can maintain the integrity of the marking without falling off after long-term high-temperature, pickling, and other metal post-processing processes, and has the characteristics of high-temperature stability, oxidation resistance, and anti-peeling.

[0022] The present application has the following advantages:

[0023] 1. The present application uses different colored ceramic powders as the marking body (such as white alumina, green chromium oxide, blue cobalt aluminum spinel, etc.), which not only meets the high-contrast visibility on different color substrates, but also has excellent high-temperature stability.

[0024] 2. The coating uses inorganic sintering aids, binders, and silicates in combination, and is simultaneously cured through a heat treatment process to form a dense ceramic coating with good adhesion and anti-peeling ability; the solvent system is flexible and suitable for the drying speed and environmental protection requirements of industrial sites.

[0025] 3. The coating is pre-cured to form a coating, and is simultaneously sintered during the heat treatment process of the metal substrate, without the need for a secondary curing process.

[0026] 4. The coating can still be kept intact after subsequent processing such as high-temperature heat treatment, pickling, and alkaline washing, meeting the long-term identification requirements of complex environments such as high temperature, oxidation, and acid-base treatment in the automatic and intelligent production process of metal materials. It is easy to apply to intelligent manufacturing systems of various alloys. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0028] Figure 1 The photo of the coating of Example 1 after 1000℃ heat treatment for 2 hours.

[0029] Figure 2 The morphology comparison diagram of the coating section and alumina powder raw material, wherein (a) is Figure 1 the scanning electron microscope (SEM) diagram of the coating section, and (b) is the morphology diagram of the alumina powder raw material before sintering.

[0030] Figure 3The contrastive photos of the coating of Example 2 before and after flushing in hydrogen chloride solution, wherein (a) is the photo before flushing, and (b) is the photo after flushing.

[0031] Figure 4 The SEM section morphology photos of the marking coating obtained under different mass fractions of sodium silicate pentahydrate, wherein (a) corresponds to a mass fraction of sodium silicate of 10%, and (b) corresponds to a mass fraction of sodium silicate of 75%. DETAILED DESCRIPTION

[0032] To make the technical problems, technical solutions and advantages to be solved by the present application clearer, the following will be described in detail with reference to the drawings and specific examples.

[0033] Example 1

[0034] (1) 70 parts of deionized water and 30 parts of sodium silicate pentahydrate were weighed in a beaker according to the weight fraction, stirred and mixed, and left to dissolve, to obtain a sodium silicate solution. To accelerate dissolution, the solution can be heated in an oven at 60°C for 30 minutes until it is clear.

[0035] (2) 55 parts of alumina, 15 parts of magnesium oxide and 10 parts of calcium oxide were weighed according to the weight fraction, and slowly added to the sodium silicate solution obtained in step (1), and continuously stirred for 30 minutes, so that the solid particles were uniformly dispersed in the solution to form a coating slurry.

[0036] (3) 10 parts of carrageenan were weighed according to the weight fraction, and slowly added to the coating slurry obtained in step (2), and continuously stirred until uniform, to improve the adhesion of the coating, so that the high-temperature-resistant alumina-based marking coating was prepared.

[0037] (4) The uniformly mixed coating slurry was moved into a needle tube or a suitable container, and was labeled according to the required shape (such as a number), and was uniformly coated onto the surface of the carbon steel material, and was dried at 55°C by hot air, and was basically shaped by using the adhesion of carrageenan.

[0038] (5) Then the steel material after labeling was placed in a high-temperature furnace for heat treatment, the temperature range was controlled at 1000°C, and the heat preservation time was 120 minutes, so that the coating was solidified to form a stable inorganic network structure, thereby obtaining a ceramic coating which is resistant to high temperature, oxidation and spalling.

[0039] Example 2

[0040] (1) 65 parts of deionized water and 35 parts of sodium silicate pentahydrate were weighed in a beaker according to the weight fraction, stirred and mixed, and left to dissolve, to obtain a sodium silicate solution.

[0041] (2) According to the weight fraction, 60 parts of alumina, 10 parts of magnesium oxide, 5 parts of calcium oxide, and 5 parts of yttrium oxide (extra sintering aid) are weighed and slowly added to the sodium silicate solution obtained in step (1), and stirred for 30 minutes to uniformly disperse the solid particles in the solution to form a coating slurry.

[0042] (3) According to the weight fraction, 8 parts of carrageenan are weighed and slowly added to the coating slurry obtained in step (2), and continue to stir until uniform, to prepare a high-temperature-resistant alumina-based marking paint.

[0043] (4) The uniformly mixed coating slurry is loaded into a needle tube or a suitable container, and uniformly coated onto the surface of the intelligent steel according to the required shape, and dried by hot air at 55°C to make it basically shaped.

[0044] (5) Then put the steel after the mark into the high-temperature furnace for heat treatment, the temperature range is controlled at 1000°C, and the heat preservation time is 300 minutes, so that the coating is solidified, and the oxidation resistance and high-temperature stability are improved.

[0045] Example 3

[0046] (1) According to the weight fraction, 75 parts of deionized water and 25 parts of sodium silicate pentahydrate are weighed and placed in a beaker, stirred and mixed, and then allowed to dissolve, to obtain a sodium silicate solution.

[0047] (2) According to the weight fraction, 50 parts of alumina, 20 parts of magnesium oxide, and 10 parts of calcium oxide are weighed and slowly added to the sodium silicate solution obtained in step (1), and stirred for 30 minutes to uniformly disperse the solid particles in the solution to form a coating slurry.

[0048] (3) According to the weight fraction, 10 parts of carrageenan are weighed and slowly added to the coating slurry obtained in step (2), and continue to stir until uniform, to prepare a high-temperature-resistant alumina-based marking paint.

[0049] (4) The uniformly mixed coating slurry is loaded into a needle tube or a suitable container, and uniformly coated onto the surface of the intelligent steel according to the required shape, and dried by hot air at 55°C to make it basically shaped.

[0050] (5) Then put the steel after the mark into the high-temperature furnace for heat treatment, the temperature range is controlled at 1000°C, and the heat preservation time is 300 minutes, so that the coating is solidified, and the oxidation resistance and high-temperature stability are improved.

[0051] Comparative Example 1

[0052] In step (1), according to the weight fraction, 90 parts of deionized water and 10 parts of sodium silicate pentahydrate are weighed and placed in a beaker, stirred and mixed, and then allowed to dissolve, to obtain a sodium silicate solution. The other steps are the same as Example 1.

[0053] Comparative Example 2

[0054] In step (1), 15 parts by weight of deionized water and 75 parts by weight of sodium silicate pentahydrate were weighed into a beaker, stirred and mixed, and left to dissolve, to obtain a sodium silicate solution. The other steps were the same as in Example 1.

[0055] The surface morphology of the coating obtained after heat treatment in Example 1 is shown in Figure 1 . It can be seen that the coating did not deform or peel off after heat treatment.

[0056] The cross-section of the alumina marking coating in Example 1 was tested by scanning electron microscopy (SEM), and the morphology is shown in Figure 2 (a). From Figure 2 (a), it can be clearly observed that, compared with the original alumina particle raw material Figure 2 (b), the surface roughness of the alumina particles in the coating after sintering increased significantly, and partial connection areas appeared between the particles, the interface between the particles was no longer completely separated, and a bridging structure was formed locally. This indicates that, during the heat treatment process, physical sintering or mechanical interlocking may occur between the alumina particles due to the sintering aid effect of the binder, thereby forming a network structure at the microscale and providing certain bonding strength.

[0057] This structure not only improves the compactness of the overall coating, but also enhances the micro bonding strength to some extent, which helps to improve the stability and adhesion performance of the marking coating in high-temperature treatment and subsequent acid and alkali environments. This micro feature further demonstrates the applicability and superiority of the alumina and other inorganic ceramic coatings of the present application in the heat treatment process of steel or non-ferrous metals.

[0058] The alumina marking coating of Example 2 was continuously flushed in a 30% volume fraction of hydrogen chloride solution for 5 minutes to simulate the steel pickling environment, and the before-and-after comparison is shown in Figure 3 , wherein Figure 3 (a) is a photo of the coating before flushing, Figure 3 (b) is a photo of the coating after flushing. Observation of the carbon steel sample coated with the alumina-based inorganic ceramic coating of the present application found that the marking was still clearly discernible, and the coating did not significantly peel off or erode, indicating that the coating has good chemical stability in an acidic environment.

[0059] Part of the marking coating of Example 3 was removed by external force and immersed in a 20% mass fraction of sodium hydroxide solution for 5 minutes, and the weight change of the coating before and after immersion is shown in Table 1. This indicates that the marking coating has good alkali resistance, and even in a concentrated alkali immersion environment, only a small amount of material is corroded or dissolved, and the mass does not significantly decrease, so it can be stably applied in certain alkaline working environments.

[0060] Table 1

[0061]

[0062] Figure 4 The scanning electron microscope (SEM) cross-sectional morphology of the obtained marking coating under different mass fractions of sodium silicate is shown. Among them Figure 4 (a) is the cross-sectional morphology of the coating obtained in Comparative Example 1, corresponding to a sodium silicate mass fraction of 10%, Figure 4 (b) is the cross-sectional morphology of the coating obtained in Comparative Example 2, corresponding to a sodium silicate mass fraction of 75%.

[0063] From Figure 4 (a) it can be observed that when the mass fraction of sodium silicate is low, the connection structure between the alumina particles in the coating is relatively sparse, and the particle interface is loosely combined, indicating that low content of sodium silicate cannot form a continuous silicon-oxygen network structure during high-temperature sintering, resulting in insufficient overall mechanical strength of the coating and decreased adhesion to the metal substrate, which is prone to falling off during heat treatment or use. At the same time, the proportion of free water in the low-sodium silicate content system is relatively high, and the water will volatilize violently during heat treatment, forming micropores or stress concentration zones in the coating, thereby causing cracks and leading to marking failure.

[0064] In contrast, Figure 4 In the high-sodium silicate system shown in (b), the alumina particles have formed obvious connection bridge structures, indicating that sodium silicate promotes the bonding reaction between the particles at high temperatures, thereby imparting higher density and structural strength to the coating and effectively enhancing its bonding force to the metal substrate. However, it is worth noting that too high a proportion of sodium silicate will significantly increase the viscosity of the slurry, affecting the uniform spreading of the coating on the metal surface, and easily causing premature solidification at room temperature, reducing its storage stability and on-site operation flexibility.

[0065] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical scope disclosed by the present application, which 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 high-temperature resistant ceramic-based marking coating, characterized in that, The coating comprises, by weight, 20-80 parts solvent, 50-100 parts ceramic powder, 10-40 parts inorganic sintering aid, 5-30 parts binder, and 10-40 parts hydrated sodium silicate.

2. The high-temperature resistant ceramic-based marking coating according to claim 1, characterized in that, The solvent is selected from at least one of deionized water, ethanol and acetone, preferably water.

3. The high-temperature resistant ceramic-based marking coating according to claim 1, characterized in that, The ceramic powder is selected from at least one of alumina, zirconium oxide, chromium oxide, and cobalt aluminum spinel.

4. The high-temperature resistant ceramic-based marking coating according to claim 1, characterized in that, The inorganic sintering aid is selected from at least two of magnesium oxide, calcium oxide, and yttrium oxide, preferably a mixture of 5 to 20 parts magnesium oxide and 5 to 20 parts calcium oxide.

5. The high-temperature resistant ceramic-based marking coating according to claim 1, characterized in that, The binder is a thickening gelling agent selected from at least one of carrageenan, gelatin, sodium carboxymethyl cellulose (CMC-Na), and sodium alginate.

6. The high-temperature resistant ceramic-based marking coating according to claim 1, characterized in that, The hydrated sodium silicate is selected from at least one of sodium silicate pentahydrate and sodium silicate nonahydrate.

7. The method for preparing the high-temperature resistant ceramic-based marking coating according to any one of claims 1 to 6, characterized in that, Includes the following steps: (1) Add hydrated sodium silicate to the solvent and dissolve to obtain a transparent solution; (2) Add ceramic powder and inorganic sintering aid to the solution obtained in step (1) and stir evenly to form ceramic slurry; (3) Add binder to the ceramic slurry obtained in step (2) and stir until fully mixed to form a pre-curable slurry with higher viscosity; (4) Apply the pre-curable slurry obtained in step (3) to the surface of the substrate material to be marked, and form a preliminary cured mark after pre-drying; (5) Heat-treat the marked substrate material to form a ceramic-based marking coating.

8. The method for preparing the high-temperature resistant ceramic-based marking coating according to claim 7, characterized in that, In step (4), the pre-drying heating temperature is 50~80°C and the heating time is 5~10 minutes.

9. The method for preparing the high-temperature resistant ceramic-based marking coating according to claim 7, characterized in that, In step (5), the heat treatment temperature is 500~1100℃ and the time is 1~10 hours.

10. The application of the high-temperature resistant ceramic-based marking coating according to any one of claims 1 to 6, characterized in that, The coating is used as a marker on the surface of various metal substrates.

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