CN112500724A - High-performance sliding brick coating containing expanded graphite and preparation method thereof - Google Patents

Abstract

The invention relates to a high-performance sliding plate brick coating containing expanded graphite and a preparation method thereof, wherein the sliding plate brick coating comprises the following raw materials: 15-21% of expanded graphite, 0.5-1.5% of organic bentonite, 1-3% of a dispersant, 1-3% of boron carbide, 0.5-1.5% of gum arabic powder, 71-80% of deionized water, and 0.5-1% of sodium carboxymethylcellulose and 0.8-1.5% of a defoaming agent. The sliding plate brick coating has the characteristics of good stability, strong adhesiveness, high bonding strength with the sliding plate brick and good smoothness of a coated working surface. The coating has the specific gravity of 1.00-1.50, the viscosity of 800-1500 mPa.s, the adhesive force of 1-3 grade, the pH value of 7-8 and the suspension stability period (without layering) of more than or equal to 30 days.

Description

High-performance sliding brick coating containing expanded graphite and preparation method thereof

Technical Field

The invention relates to a high-performance sliding brick coating containing expanded graphite and a preparation method thereof, belonging to the field of inorganic non-metallic materials.

Background

The sliding gate is an important functional refractory material for steelmaking continuous casting, the sliding plate brick is a key component of a sliding gate system, and the quality of the performance of the sliding plate brick directly determines the steel flow control effect of the sliding gate system. The sliding plate brick realizes the control of the molten steel flow rate and the switch through the relative sliding of the upper sliding plate brick and the lower sliding plate brick in the continuous casting use process, the friction force between the sliding surfaces of the sliding plate bricks is an important factor influencing the use of the sliding plate brick, and the phenomena of galling, abrasion and the like can occur on the surface of the sliding plate due to the frequent sliding of the sliding plate bricks under the high-temperature condition, so that the friction resistance between the upper sliding plate and the lower sliding plate is increased, and the flexibility of the sliding operation and the accuracy of the molten steel flow control are reduced.

In order to reduce the friction between the sliding plate bricks and reduce the damage of the sliding plate bricks caused by mechanical abrasion, the working surface of the sliding plate bricks is coated with graphite paint to achieve the effects of lubrication and abrasion reduction, so that the performance of the sliding plate brick paint has important influence on the use of the sliding plate bricks. However, in the use process of the current domestic sliding plate coating, the coating is often stored and precipitated, secondary stirring is needed in the use process, the adhesion between the coating and the sliding plate brick is poor, the bonding strength is low, the coating is easy to oxidize in high-temperature use, the coating is easy to fall off in the use process, and the like, so that the use effect and the service life of the sliding plate brick are directly influenced. Therefore, a high-performance coating for sliding bricks needs to be further developed to improve the stability, spreadability and adhesion of the coating for sliding bricks, so as to achieve the purpose of improving the using effect of the sliding bricks.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide a high-performance sliding plate brick coating containing expanded graphite and a preparation method thereof.

In order to achieve the purpose, the invention adopts the technical scheme that:

the high-performance sliding brick coating containing expanded graphite comprises the following raw materials in percentage by weight: 15-21% of expanded graphite, 0.5-1.5% of organic bentonite, 1-3% of a dispersant, 1-3% of boron carbide, 0.5-1.5% of gum arabic powder, 71-80% of deionized water, and additionally 0.5-1% of sodium carboxymethylcellulose and 0.8-1.5% of a defoaming agent.

The particle size of the expanded graphite is 600 meshes, the expansion volume is 10-20 mL/g, and the mass fraction of the carbon content is more than or equal to 90%.

The granularity of the organic bentonite is 200 meshes, and the granularity of the boron carbide is 325 meshes.

The dispersant is NNO, the Arabian gum powder is food grade Arabian gum powder, and the defoaming agent is tributyl phosphate.

The viscosity of the sodium carboxymethylcellulose used was 1200-1300 mPas in a 2% aqueous solution at 25 ℃.

The water temperature of the deionized water is 50-70 ℃.

The preparation method of the sliding brick coating comprises the following steps:

(1) weighing the raw materials according to the proportion, adding the expanded graphite into a ball milling tank, carrying out ball milling for 20-30 h, and carrying out mechanical stripping to obtain treated expanded graphite powder for later use;

(2) adding sodium carboxymethylcellulose, gum arabic powder, 50% of defoaming agent and deionized water into a stirring pot, firstly stirring at low speed for 0.5-1 h, and stirring at high speed for 1.5-2 h; then adding boron carbide, organic bentonite and a dispersing agent, and stirring at a high speed for 1-2 h; then adding the expanded graphite powder subjected to ball milling and the rest 50% of defoaming agent, stirring at a low speed for 1-2 h, and stirring at a high speed for 2-3 h to obtain mixed slurry; the low speed is 150 revolutions per minute, and the high speed is 400 revolutions per minute;

(3) adding the mixed slurry into a ball milling tank, and carrying out ball milling for 12-15 h to obtain the product.

The invention has the beneficial effects that:

the coating of the sliding plate brick has good uniformity and stability, does not generate precipitation after being stored for a long time, avoids secondary stirring before use, has good adhesiveness and spreadability on the sliding plate brick material, and ensures that the sliding plate coating does not fall off in the production and use processes. The expanded graphite after ball milling treatment is added into the raw materials, so that the sliding plate coating has better lubricity, the sliding friction force of the sliding plate brick in the using process is reduced, and the usability of the sliding plate brick is improved. The specific analysis is as follows:

(1) the sodium carboxymethylcellulose, the gum arabic powder and the organic bentonite added in the raw materials have the functions of thickening, anti-settling and emulsifying in an aqueous system, and form hydrocolloid after being dissolved. The three raw materials are compounded and introduced, so that better thickening, plasticizing and anti-settling effects can be achieved, the stability of the sliding plate brick coating is ensured, and the sodium carboxymethyl cellulose, the gum arabic powder and the organic bentonite also have a bonding effect and can be used as a bonding agent to improve the adhesiveness and bonding strength between the coating and the sliding plate brick.

(2) The carbon source in the raw materials of the invention adopts expanded graphite fine powder, and the expanded graphite is used as a novel functional carbon material and is a loose and porous vermicular substance. The graphite has excellent cold and heat resistance, corrosion resistance, self-lubrication and other performances of natural graphite, and has the characteristics of softness, compression resilience, adsorbability, environmental compatibility and the like which are not possessed by the natural graphite. The invention relates to a method for preparing expanded graphite, which comprises the steps of preparing expanded graphite, peeling graphite flakes with nanometer thickness from the expanded graphite by mechanical ball milling, and further adding the expanded graphite into a sliding brick coating to improve the adhesion strength of the coating.

(3) According to the invention, the raw material adopts boron carbide as an antioxidant, and the boron carbide and oxygen react with each other preferentially to achieve an antioxidant effect due to higher activity than graphite, so that the antioxidant property of the coating is improved; by adopting the dispersant NNO, the dispersion effect on the expanded graphite is good, the graphite agglomeration can be avoided, and the uniformity of the coating components of the sliding plate is improved.

(4) The raw materials of the invention adopt deionized water, thus avoiding coating precipitation caused by the damage of impurities in water to the sol formed by sodium carboxymethylcellulose, gum arabic powder and organic bentonite. Meanwhile, deionized water with the temperature of 50-70 ℃ is used in the production process, so that the forming time of the hydrosol can be reduced, the stirring time is shortened, and the formation of the hydrosol is more sufficient.

(5) The product adopts a specific preparation process, wherein sodium carboxymethylcellulose, a part of defoaming agent, gum arabic powder and deionized water are stirred at a low speed and then stirred at a high speed to promote full sol of the sodium carboxymethylcellulose, the defoamer, the gum arabic powder and the deionized water to prepare a primary sol mother solution, then the organic bentonite, the boron carbide and the dispersing agent are added, and the organic bentonite is stirred at a high speed to promote the boron carbide and the dispersing agent to be uniformly dispersed in a sol while sol is formed, so that the sol mother solution containing the antioxidant and the dispersing agent of the product is obtained, the sol mother solution can promote the uniform dispersion of graphite in the stirring process after the graphite is added, and meanwhile, the problem that the boron carbide is not well dispersed when being added with the graphite is avoided, and the component uniformity of the product is ensured; the defoaming agent is added in several times, so that foams in different stages can be eliminated, and the defoaming effect is better; the product of the invention also adds a ball milling process in the production process, and can further promote the uniform dispersion of each component in the ball milling process and improve the component uniformity and stability of the product.

(6) The sliding plate brick coating has excellent performance indexes, wherein the performance indexes are as follows: the specific gravity is 1.10-1.50, the viscosity (25 ℃) is 800-1500 mPas, the adhesive force is 1-3 grade, the PH value is 7-8, and the suspension stability period (without layering) is more than or equal to 30 days.

Detailed Description

The following examples further illustrate the embodiments of the present invention in detail.

Example 1

The high-performance sliding brick coating containing expanded graphite comprises the following raw materials in percentage by weight: 15 percent of expanded graphite, 0.8 percent of organic bentonite, 2 percent of dispersant, 2 percent of boron carbide, 1.2 percent of gum arabic, 79 percent of deionized water, and additionally 1 percent of sodium carboxymethylcellulose and 0.8 percent of defoamer in the total amount of the raw materials.

The particle size of the expanded graphite is 600 meshes, the expansion volume is 10-20 mL/g, and the mass fraction of the carbon content is more than or equal to 90%; the granularity of the organic bentonite is 200 meshes, and the granularity of the boron carbide is 325 meshes; the dispersant is NNO, the Arabic gum powder is food-grade Arabic gum powder, and the defoaming agent is tributyl phosphate; the viscosity of the adopted sodium carboxymethylcellulose in a 2% aqueous solution at 25 ℃ is 1200-1300 mPas; the water temperature of the deionized water is 50-70 ℃.

The preparation method of the sliding plate brick coating comprises the following steps:

(1) weighing the raw materials according to the proportion, adding the expanded graphite into a ball milling tank, carrying out ball milling for 20-30 h, and carrying out mechanical stripping to obtain treated expanded graphite powder for later use;

(2) adding sodium carboxymethylcellulose, gum arabic powder, 50% of defoaming agent and deionized water into a stirring pot, firstly stirring at low speed for 0.5-1 h, and stirring at high speed for 1.5-2 h; then adding boron carbide, organic bentonite and a dispersing agent, and stirring at a high speed for 1-2 h; then adding the expanded graphite powder subjected to ball milling and the rest 50% of defoaming agent, stirring at a low speed for 1-2 h, and stirring at a high speed for 2-3 h to obtain mixed slurry; the low speed is 150 revolutions per minute, and the high speed is 400 revolutions per minute;

(3) adding the mixed slurry into a ball milling tank, and carrying out ball milling for 12-15 h to obtain the product.

The physical properties of the sliding brick coating are detected, wherein the specific gravity is 1.10, the viscosity (25 ℃) is 1500 mPa.s, the adhesive force is grade 3, the PH value is 7, and the suspension stability period (no layering) is more than or equal to 30 days.

Example 2

The high-performance sliding brick coating containing expanded graphite comprises the following raw materials in percentage by weight: 21 percent of expanded graphite, 0.5 percent of organic bentonite, 1 percent of dispersant, 1 percent of boron carbide, 0.5 percent of gum arabic powder, 76 percent of deionized water, and additionally 0.5 percent of sodium carboxymethylcellulose and 1.5 percent of defoamer in the total amount of the raw materials.

The particle size of the expanded graphite is 600 meshes, the expansion volume is 10-20 mL/g, and the mass fraction of the carbon content is more than or equal to 90%; the granularity of the organic bentonite is 200 meshes, and the granularity of the boron carbide is 325 meshes; the dispersant is dispersant NNO; the viscosity of the adopted sodium carboxymethylcellulose in a 2% aqueous solution at 25 ℃ is 1200-1300 mPas; the water temperature of the deionized water is 50-70 ℃.

The preparation method of the sliding plate brick coating is the same as that in example 1, and the physical properties of the sliding plate brick coating are detected, wherein the specific gravity is 1.50, the viscosity (25 ℃) is 800 mPa.s, the adhesive force is 1 grade, the PH value is 8, and the suspension stability period (no layering) is more than or equal to 30 days.

Example 3

The high-performance sliding brick coating containing expanded graphite comprises the following raw materials in percentage by weight: 16 percent of expanded graphite, 0.7 percent of organic bentonite, 1.3 percent of dispersant, 1.3 percent of boron carbide, 0.7 percent of gum arabic powder, 80 percent of deionized water, and additionally 0.7 percent of sodium carboxymethylcellulose and 1 percent of defoamer based on the total amount of the raw materials.

The particle size of the expanded graphite is 600 meshes, the expansion volume is 10-20 mL/g, and the mass fraction of the carbon content is more than or equal to 90%; the granularity of the organic bentonite is 200 meshes, and the granularity of the boron carbide is 325 meshes; the dispersant is dispersant NNO, and the defoaming agent is tributyl phosphate; the viscosity of the adopted sodium carboxymethylcellulose in a 2% aqueous solution at 25 ℃ is 1200-1300 mPas; the water temperature of the deionized water is 50-70 ℃.

The preparation method of the sliding plate brick coating is the same as that in example 1, and the physical properties of the sliding plate brick coating are detected, wherein the specific gravity is 1.18, the viscosity (25 ℃) is 1050 mPa.s, the adhesive force is 2 grades, the PH value is 8, and the suspension stability period (no layering) is more than or equal to 30 days.

Example 4

The high-performance sliding brick coating containing expanded graphite comprises the following raw materials in percentage by weight: 20 percent of expanded graphite, 1.5 percent of organic bentonite, 3 percent of dispersant, 3 percent of boron carbide, 1.5 percent of gum arabic powder, 71 percent of deionized water, and additionally 0.8 percent of sodium carboxymethylcellulose and 1.2 percent of defoamer in the total amount of the raw materials.

The particle size of the expanded graphite is 600 meshes, the expansion volume is 10-20 mL/g, and the mass fraction of the carbon content is more than or equal to 90%; the granularity of the organic bentonite is 200 meshes, and the granularity of the boron carbide is 325 meshes; the dispersant is NNO, and the Arabic gum powder is food-grade Arabic gum powder; the viscosity of the adopted sodium carboxymethylcellulose in a 2% aqueous solution at 25 ℃ is 1200-1300 mPas; the water temperature of the deionized water is 50-70 ℃.

The preparation method of the sliding plate brick coating is the same as that in example 1, and the physical properties of the sliding plate brick coating are detected, wherein the specific gravity is 1.36, the viscosity (25 ℃) is 1280 mPa.s, the adhesive force is 2 grades, the PH value is 7, and the suspension stability period (no layering) is more than or equal to 30 days.

Claims (7)

1. The high-performance sliding brick coating containing expanded graphite is characterized by comprising the following raw materials in percentage by weight: 15-21% of expanded graphite, 0.5-1.5% of organic bentonite, 1-3% of a dispersant, 1-3% of boron carbide, 0.5-1.5% of gum arabic powder, 71-80% of deionized water, and additionally 0.5-1% of sodium carboxymethylcellulose and 0.8-1.5% of a defoaming agent.

2. The coating for the sliding plate brick as claimed in claim 1, wherein the expanded graphite has a particle size of 600 mesh, an expanded volume of 10-20 mL/g, and a carbon content of not less than 90% by mass.

3. The coating for a sliding plate brick of claim 1 wherein the organobentonite has a particle size of 200 mesh and the boron carbide has a particle size of 325 mesh.

4. The coating for a slide plate brick as claimed in claim 1, wherein the dispersant is NNO, the gum arabic powder is food grade gum arabic powder, and the defoaming agent is tributyl phosphate.

5. The coating composition according to claim 1, wherein the viscosity of the sodium carboxymethylcellulose used is 1200-1300 mPas in a 2% aqueous solution at 25 ℃.

6. The slide plate brick coating of claim 1 wherein the deionized water has a water temperature of 50 ℃ to 70 ℃.

7. The method of preparing a slide brick coating of claim 1 comprising the steps of:

(1) weighing the raw materials according to the proportion, adding the expanded graphite into a ball milling tank, carrying out ball milling for 20-30 h, and carrying out mechanical stripping to obtain treated expanded graphite powder for later use;

(2) adding sodium carboxymethylcellulose, gum arabic powder, 50% of defoaming agent and deionized water into a stirring pot, firstly stirring at low speed for 0.5-1 h, and stirring at high speed for 1.5-2 h; then adding boron carbide, organic bentonite and a dispersing agent, and stirring at a high speed for 1-2 h; then adding the expanded graphite powder subjected to ball milling and the rest 50% of defoaming agent, stirring at a low speed for 1-2 h, and stirring at a high speed for 2-3 h to obtain mixed slurry; the low speed is 150 revolutions per minute, and the high speed is 400 revolutions per minute;

(3) adding the mixed slurry into a ball milling tank, and carrying out ball milling for 12-15 h to obtain the product.