CN115197593B - Surface coating of wire mesh and preparation method thereof - Google Patents

Surface coating of wire mesh and preparation method thereof Download PDF

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CN115197593B
CN115197593B CN202210162515.6A CN202210162515A CN115197593B CN 115197593 B CN115197593 B CN 115197593B CN 202210162515 A CN202210162515 A CN 202210162515A CN 115197593 B CN115197593 B CN 115197593B
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wire mesh
surface coating
solution
metal wire
titanium dioxide
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CN115197593A (en
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刘静
王昱
羿昌波
张静
李来平
刘高建
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Western Baode Technologies Co ltd
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Abstract

The invention belongs to the technical field of SCR catalyst carrier processing, and particularly relates to a preparation method of a surface coating of a metal wire mesh. The surface coating of the wire mesh comprises sodium silicate, sodium carboxymethylcellulose, aluminum oxide, titanium dioxide and basalt fiber; and the aluminum oxide, the titanium dioxide and the basalt fiber are dissolved in a mixed solution prepared from the sodium silicate and the sodium carboxymethyl cellulose. A method for preparing a surface coating comprises the following steps: mixing sodium silicate solution and sodium carboxymethyl cellulose solution, adding Al into the mixed solution 2 O 3 Basalt fiber and TiO 2 Stirring to obtain a binding agent slurry; placing the acid-washed metal wire mesh in the bonding agent slurry, and repeatedly dipping and drying under vacuum; and sintering the metal wire mesh to obtain the coated surface coating. The coating and the preparation method provided by the invention can increase the contact area between the catalyst and the carrier and improve the bonding strength between the carrier and the catalyst, thereby improving the catalytic denitration effect.

Description

Surface coating of wire mesh and preparation method thereof
Technical Field
The invention belongs to the technical application field of SCR catalyst carrier processing, and particularly relates to a surface coating of a metal wire mesh and a preparation method thereof.
Background
In recent years, NO is produced by industrial activities such as fossil fuel combustion and nitric acid production x Causing serious pollution to air, and easily generating environmental pollution such as acid rain, photochemical smog, ozone layer cavities and the like. The Selective Catalytic Reduction (SCR) technology has the characteristics of mature process, high removal efficiency, stable system operation and the like, and is the preferred NO at the present stage x And (4) a treatment method. At present, the research on the SCR catalyst carrier mainly aims at the direction of supporting the catalyst on the ceramic substrate, and the related research on the metal substrate supported catalyst is less.
Compared with ceramics, metals have the advantages of good heat transfer property and strong impact resistance. The metal wire mesh is used as a base material, so that the heat and mass transfer performance can be improved, the pressure drop is reduced, the mechanical strength is increased, the geometric flexibility of the catalyst is improved, and the defects of the traditional ceramic carrier catalyst can be overcome to a great extent. In addition, the porous structure of the metal wire mesh has a larger specific surface area, so that the adhesion amount of the catalyst is effectively increased, and the catalytic efficiency is improved.
However, the difference between the physical and chemical properties of the metal carrier and the inorganic catalyst is large, and the difference in thermal expansion coefficient causes the poor adhesive strength between the metal carrier and the inorganic catalyst, thereby affecting the service life and the catalytic effect of the catalyst.
In order to solve the above problems, the present invention provides a surface coating of a wire mesh and a method for preparing the same.
Disclosure of Invention
An object of the present invention is to solve at least one of the above problems or disadvantages and to provide at least one advantage which will be described later.
Still another object of the present invention is to provide a surface coating layer for a wire mesh, which is formed by coating a coating layer similar to a catalyst component on the surface of the wire mesh, and can increase the contact area between the catalyst and the carrier, improve the bonding strength between the carrier and the catalyst, and further improve the catalytic denitration effect.
Still another object of the present invention is to provide a method for preparing a surface coating of a wire mesh, which is used to coat the surface coating on the wire mesh, so as to further improve catalytic denitration effect.
To achieve these objects and other advantages in accordance with the purpose of the invention, there is provided a surface coating of a wire-net, characterized by comprising the following raw materials:
sodium silicate, sodium carboxymethylcellulose, aluminum oxide, titanium dioxide and basalt fiber;
wherein the aluminum oxide, the titanium dioxide and the basalt fiber are dissolved in a mixed solution prepared from the sodium silicate and the sodium carboxymethyl cellulose.
Preferably, the mass ratio of the sodium silicate solution to the sodium carboxymethyl cellulose solution is 3:1.
Preferably, the mass fractions of the aluminum oxide, the titanium dioxide and the basalt fiber in the mixed solution are 70-85wt.%, 15-20wt.% and 1-2wt.%, respectively.
Preferably, the particle size of the aluminum oxide is 15-50 μm, the particle size of the titanium dioxide is 100-300 nm, the diameter of the basalt fiber is <10 μm, and the length-diameter ratio is 8:1.
The invention also provides a preparation method of the surface coating of the metal wire mesh, which comprises the following steps:
mixing a sodium silicate solution and a sodium carboxymethyl cellulose solution to obtain a mixed solution;
adding aluminum oxide, basalt fibers and titanium dioxide into the mixed solution, and stirring to obtain a binder slurry;
placing the acid-washed metal wire mesh in the bonding agent slurry, and repeatedly dipping and drying in a vacuum environment;
and sintering the metal wire mesh to obtain the surface coating coated on the metal wire mesh.
Preferably, the mass ratio of the sodium silicate solution to the sodium carboxymethyl cellulose solution is 3:1, the sodium silicate solution modulus is 3.25-3.35, and the sodium carboxymethyl cellulose solution concentration is 3wt.%.
Preferably, the aluminum oxide, basalt fiber and titanium dioxide are added into the mixed solution, and after stirring, the obtained binder slurry specifically comprises:
adding 70-85wt.% of spherical aluminum oxide, 1-2wt.% of basalt fiber and 15-20wt.% of titanium dioxide into the mixed solution in sequence, and stirring for 1.5h;
and after stirring, carrying out ultrasonic treatment in an ultrasonic oscillator for 1h, and standing for 12h to obtain the binder slurry.
Preferably, the particle size of the aluminum oxide is 15-50 μm, the particle size of the titanium dioxide is 100-300 nm, the diameter of the basalt fiber is <10 μm, and the length-diameter ratio is 8:1.
Preferably, the step of placing the acid-washed wire mesh in the binder slurry, and the step of repeatedly dipping and drying in a vacuum environment specifically comprises the steps of:
immersing the metal wire mesh in an acid solution for ultrasonic treatment, washing and drying;
and placing the acid-washed wire mesh into the bonding agent slurry, vacuumizing to-0.098 MPa, soaking for 0.5h, drying at 100-120 ℃ for 6-10h, and repeating soaking and drying for 2-4 times.
Preferably, sintering the wire mesh to obtain the surface coating coated on the wire mesh specifically includes:
and (3) placing the wire mesh in a muffle furnace, heating to 400-600 ℃ at a heating rate of 120 ℃/h, and preserving heat for 1-3h to obtain the surface coating of the wire mesh.
The invention has the advantages of
1. The surface coating of the metal wire mesh provided by the invention improves the bonding strength and durability of a catalyst and the metal wire mesh.
2. The surface coating of the metal wire mesh provided by the invention adopts basalt fibers, so that the mechanical property of the coating is improved.
3. The invention provides a surface coating of a metal wire mesh, which changes the adhesion degree between the coating and the metal wire mesh and the specific surface area of the coating by changing the particle grading of powder in slurry.
4. According to the preparation method of the surface coating of the metal wire mesh, provided by the invention, the coating is coated on the metal wire mesh through a simple and easy-to-operate process, so that the combination of the metal wire mesh and an SCR (selective catalytic reduction) catalyst is improved.
Drawings
Fig. 1 is a schematic flow chart of a method for preparing a surface coating layer of a wire-net according to the present invention.
Detailed Description
The present invention is further described in detail below with reference to the attached drawings so that those skilled in the art can implement the invention by referring to the description text.
It will be understood that terms such as "having," "including," and "comprising," as used herein, do not preclude the presence or addition of one or more other elements or groups thereof.
The invention provides a surface coating of a wire mesh, which comprises the following raw materials: sodium silicate, sodium carboxymethylcellulose, aluminum oxide, titanium dioxide and basalt fiber;
the aluminum oxide, the titanium dioxide and the basalt fiber are dissolved in a mixed solution prepared from the sodium silicate and the sodium carboxymethyl cellulose, and the mass ratio of the sodium silicate solution to the sodium carboxymethyl cellulose solution is 3:1.
After sodium silicate is added into the surface coating, the main components after the surface coating is hardened are silica sol and solid, so that the specific surface area is large, and the bonding effect is greatly improved; and the coating does not decompose under the working condition (300-400 ℃), thereby ensuring the adhesive force of the coating.
Sodium carboxymethyl cellulose is added into the surface coating and is used as a dispersing agent and a suspending agent to adjust the stability of the slurry, so that the solid components of the slurry are uniformly distributed in the solvent and do not delaminate for a long time; as a binder, the binding effect is improved; as pore-forming agent, the material is decomposed in the coating sintering process, a large number of micropores are formed in the coating, and the specific surface area of the coating is obviously increased.
Gamma-Al added in surface coating 2 O 3 The catalyst is a porous substance, has a large specific surface area, is used as a carrier medium of the catalyst, and effectively increases the loading capacity of the carrier. Further, gamma-Al 2 O 3 Has strong adsorption force, so that the coating is firmly attached and is not easy to fall off.
Titanium dioxide is added into the surface coating, so that the coating has components similar to those of the SCR catalyst, and the physical and chemical property adaptability among the metal wire mesh, the coating and the SCR catalyst is improved.
The basalt fiber added into the surface coating can serve as a 'skeleton' of the coating and improve the mechanical property of the coating.
Wherein the mass fractions of the aluminum oxide, the titanium dioxide and the basalt fiber in the mixed solution are 70-85wt.%, 15-20wt.% and 1-2wt.%, respectively.
Adding 70-85wt.% of alumina as the maximum addition amount which can be met by a solvent, and if the mass fraction is less than 70%, the surface of the metal wire mesh cannot be sufficiently covered and the drying shrinkage is large; above 85%, the viscosity of the slurry is too high to meet the dipping process. The surface coating formed by the range provided by the application can solve the problem of the application.
The titanium dioxide has the function of adapting to catalyst components, and the addition amount is adjusted on the basis of the addition amount of the aluminum oxide so as to achieve the slurry fluidity meeting the process requirements.
The addition amount of the basalt fibers is higher than 2%, so that the viscosity of the slurry is increased, and the coating is too thick; below 1%, the fiber reinforcement cannot be achieved. The fiber content is increased, namely the volume ratio is increased, more fibers bear the load transmitted by the matrix, and the larger the fiber ratio is, the more the number of fibers pulled out from the fracture of the composite material is, the more the pulling work consumed by the fracture of the sample is, so that the strength of the composite material is correspondingly improved; the fiber volume content is too high, the proportion of the matrix is reduced, the matrix can not be well bonded when the composite material is formed, the load transfer function of the matrix is reduced, and the fiber does not play a role in enhancing, so that the strength of the composite material is reduced.
The contents of the three components are repeatedly and creatively tested by the inventor, so that the technical problem of the application can be solved, and the technical effect of the application can be achieved.
Wherein the grain diameter of the aluminum oxide is 15-50 μm, and the dispersion effect of the aluminum oxide powder is the best in the coating formula system of the patent. Small grain size, easy agglomeration, too large drying shrinkage and sintering shrinkage, and is not beneficial to subsequent processes.
The diameter of the basalt fiber is less than 10 mu m, and the length-diameter ratio is 8-16. The selection of the diameter and the length-diameter ratio of the basalt fiber needs to comprehensively consider the problems of fiber reinforcement, coating thickness, slurry fluidity and the like. As the length of the fibers in the composite increases, the strength of the composite increases accordingly, but increases to 10 μm, the strength gradually decreases. The reason is that when the fiber length is increased to a certain degree, the fibers are excessively bridged in the slurry and are not easily dispersed, and the mechanical property of the composite material is reduced.
The surface coating of the metal wire mesh provided by the invention can improve the bonding strength and durability of the catalyst and the metal wire mesh and improve the service efficiency of the catalyst by the cooperation of the sodium silicate, the sodium carboxymethylcellulose, the alumina and the basalt fiber, and meanwhile, the surface coating is convenient for attaching the catalyst to the surfaces of substrates with various geometric shapes, so that the surface coating meets the requirements of various catalyst environments, and the application range of the catalyst is expanded.
The invention also provides a preparation method of the surface coating of the wire mesh, which is used for preparing the surface coating and coating the surface coating on the wire mesh, and specifically as shown in figure 1, the preparation method comprises the following steps:
step 1, weighing a sodium silicate solution and a sodium carboxymethylcellulose solution in a mass ratio of 3:1, and uniformly stirring to obtain a mixed solution, wherein the modulus of the sodium silicate solution is 3.25-3.35, and the concentration of the sodium carboxymethylcellulose solution is 3wt.%;
step 2, sequentially adding 70-85wt.% of spherical Al to the mixed solution 2 O 3 1-2wt.% basalt fiber and 15-20wt.% TiO 2 Stirring for 1.5h, performing ultrasonic treatment in an ultrasonic oscillator for 1h, and standing for 12h to obtain a binder slurry; wherein the grain diameter of the aluminum oxide is 15-50 μm, the grain diameter of the titanium dioxide is 100-300 nm, and the diameter of the basalt fiber is<10 μm, aspect ratio 8:1;
step 3, immersing the metal wire mesh into an acid solution for ultrasonic treatment, washing and drying, putting the metal wire mesh into the bonding agent slurry, vacuumizing to-0.098 MPa, immersing for 0.5h, drying at 100-120 ℃ for 6-10h, and repeating the immersing and drying for 2-4 times;
and 4, placing the wire mesh in a muffle furnace, raising the temperature to 400-600 ℃ at a heating rate of 120 ℃/h, and preserving the heat for 1-3h to obtain the surface coating of the wire mesh.
Wherein the thickness of the surface coating is 30-70 μm.
The following examples are provided to illustrate the surface coatings and methods of making the same provided by the present invention.
Example 1
The invention provides a preparation method of a surface coating of a wire mesh, which comprises the following steps:
step 1, weighing a sodium silicate solution and a sodium carboxymethylcellulose solution in a mass ratio of 3:1, and magnetically stirring for 30min to obtain a mixed solution, wherein the modulus of the sodium silicate solution is 3.25-3.35, and the concentration of the sodium carboxymethylcellulose solution is 3wt.%;
step 2, adding 51.90wt.% of spherical Al with the particle size of 50 μm into the continuously stirred mixed solution in sequence 2 O 3 30.00wt.% spherical Al with a particle size of 15 μm 2 O 3 2.00wt.% basalt fiber and 16.10wt.% TiO 2 Stirring for 1.5h, performing ultrasonic treatment in an ultrasonic oscillator for 1h, and standing for 12h to obtain a binder slurry;
step 3, immersing the wire mesh in hydrochloric acid solution for ultrasonic treatment for 15min, taking out, washing with deionized water, standing for 15min, drying in an oven at 110 +/-5 ℃ for 2h, drying, putting in the bonding agent slurry, vacuumizing to-0.098 MPa, immersing for 0.5h to fully coat the slurry on the surface of the substrate, drying in the oven at 110 +/-5 ℃ for 6h, repeating the immersing and drying for 2 times;
and 4, placing the wire mesh in a muffle furnace, heating to 500 ℃ at a heating rate of 120 ℃/h, and preserving heat for 2h to obtain the surface coating of the wire mesh.
The surface coating is prepared and coated on the metal wire mesh, the surface coating is detected to have no crack or peeling, and after the surface coating is placed in an ultrasonic oscillator for 2 hours, the surface coating has total loss of 17.4 percent after a thermal shock test (a sample is rapidly cooled in the air after being heated to 900 ℃ and is repeated for 10 times).
Example 2
The invention provides a preparation method of a surface coating of a wire mesh, which comprises the following steps:
step 1, weighing a sodium silicate solution and a sodium carboxymethylcellulose solution in a mass ratio of 3:1, and magnetically stirring for 30min to obtain a mixed solution, wherein the modulus of the sodium silicate solution is 3.25-3.35, and the concentration of the sodium carboxymethylcellulose solution is 3wt.%;
step 2, adding 58.14wt.% of spherical Al with the particle size of 50 mu m into the continuously stirred mixed solution in sequence 2 O 3 23.06wt.% spherical Al with a particle size of 15 μm 2 O 3 1.16wt.% basalt fiber and 17.44wt.% TiO 2 Stirring for 1.5h, performing ultrasonic treatment in an ultrasonic oscillator for 1h, and standing for 12h to obtain a binding agent slurry;
step 3, immersing the wire mesh in hydrochloric acid solution for ultrasonic treatment for 15min, taking out, washing with deionized water, standing for 15min, drying in an oven at 110 +/-5 ℃ for 2h, drying, putting in the bonding agent slurry, vacuumizing to-0.098 MPa, immersing for 0.5h to fully coat the slurry on the surface of the substrate, drying in the oven at 110 +/-5 ℃ for 6h, repeating the immersing and drying for 3 times;
and 4, placing the wire mesh in a muffle furnace, heating to 500 ℃ at a heating rate of 120 ℃/h, and preserving heat for 3h to obtain the surface coating of the wire mesh.
The surface coating is prepared and coated on the metal wire mesh, the surface coating is detected to have no crack or peeling, and after the ultrasonic vibrator is placed for 2 hours, the total loss of the surface coating is 0.9 percent after a thermal shock test (a sample is rapidly cooled in the air after being heated to 900 ℃ and is repeated for 10 times).
Example 3
The invention provides a preparation method of a surface coating of a wire mesh, which comprises the following steps:
step 1, weighing a sodium silicate solution and a sodium carboxymethylcellulose solution in a mass ratio of 3:1, and magnetically stirring for 30min to obtain a mixed solution, wherein the modulus of the sodium silicate solution is 3.25-3.35, and the concentration of the sodium carboxymethylcellulose solution is 3wt.%;
step 2, adding 60.91wt.% spherical Al with the particle size of 50 μm into the continuously stirred mixed solution in sequence 2 O 3 20.05wt.% spherical Al with a particle size of 15 μm 2 O 3 1.04wt.% basalt fiber and 18.00wt.% TiO 2 Stirring for 1.5h, performing ultrasonic treatment in an ultrasonic oscillator for 1h, and standing for 12h to obtain a binding agent slurry;
step 3, immersing the metal wire mesh in a hydrochloric acid solution for ultrasonic treatment for 15min, taking out, washing with deionized water, standing for 15min, drying in an oven at 110 +/-5 ℃ for 2h, drying, putting in the bonding agent slurry, vacuumizing to-0.098 MPa, immersing for 0.5h to fully coat the slurry on the surface of the substrate, drying in the oven at 110 +/-5 ℃ for 6h, repeating the immersing and drying for 3 times;
and 4, placing the wire mesh in a muffle furnace, heating to 500 ℃ at a heating rate of 120 ℃/h, and preserving heat for 3h to obtain the surface coating of the wire mesh.
The surface coating is prepared and coated on the metal wire mesh, the surface coating is detected to have no crack or peeling, and after the ultrasonic vibrator is placed for 2 hours, the total loss of the surface coating is 6.3 percent after a thermal shock test (a sample is rapidly cooled in the air after being heated to 900 ℃ and is repeated for 10 times).
Example 4
The invention provides a preparation method of a surface coating of a wire mesh, which comprises the following steps:
step 1, weighing a sodium silicate solution and a sodium carboxymethylcellulose solution in a mass ratio of 3:1, and magnetically stirring for 30min to obtain a mixed solution, wherein the modulus of the sodium silicate solution is 3.25-3.35, and the concentration of the sodium carboxymethylcellulose solution is 3wt.%;
step 2, adding 70.00wt.% of spherical Al with the particle size of 45 mu m into the continuously stirred mixed solution in sequence 2 O 3 14.00wt.% spherical Al having a particle size of 20 μm 2 O 3 1.00wt.% basalt fiber and 15.00wt.% TiO 2 Stirring for 1.5h, performing ultrasonic treatment in an ultrasonic oscillator for 1h, and standing for 12h to obtainTo binder slurries;
step 3, immersing the metal wire mesh in a hydrochloric acid solution for ultrasonic treatment for 15min, taking out, washing with deionized water, standing for 15min, drying in an oven at 110 +/-5 ℃ for 2h, drying, putting in the bonding agent slurry, vacuumizing to-0.098 MPa, immersing for 0.5h to fully coat the slurry on the surface of the matrix, drying in the oven at 110 +/-5 ℃ for 6h, repeating the immersing and drying for 2 times;
and 4, placing the metal wire mesh in a muffle furnace, heating to 600 ℃ at a heating rate of 120 ℃/h, and preserving heat for 3h to obtain the surface coating of the metal wire mesh.
The surface coating is prepared and coated on the metal wire mesh, the surface coating is detected to have no crack or peeling, and after the surface coating is placed in an ultrasonic oscillator for 2 hours, the surface coating has a total loss of 9.2 percent after a thermal shock test (a sample is rapidly cooled in the air after being heated to 900 ℃ and is repeated for 10 times).
Example 5
The invention provides a preparation method of a surface coating of a wire mesh, which comprises the following steps:
step 1, weighing a sodium silicate solution and a sodium carboxymethylcellulose solution in a mass ratio of 3:1, and magnetically stirring for 30min to obtain a mixed solution, wherein the modulus of the sodium silicate solution is 3.25-3.35, and the concentration of the sodium carboxymethylcellulose solution is 3wt.%;
step 2, adding 73.00wt.% of spherical Al with the particle size of 40 μm into the continuously stirred mixed solution in sequence 2 O 3 10.00wt.% spherical Al with a particle size of 25 μm 2 O 3 1.00wt.% basalt fiber and 16.00wt.% TiO 2 Stirring for 1.5h, performing ultrasonic treatment in an ultrasonic oscillator for 1h, and standing for 12h to obtain a binder slurry;
step 3, immersing the metal wire mesh in a hydrochloric acid solution for ultrasonic treatment for 15min, taking out, washing with deionized water, standing for 15min, drying in an oven at 110 +/-5 ℃ for 2h, drying, putting in the bonding agent slurry, vacuumizing to-0.098 MPa, immersing for 0.5h to fully coat the slurry on the surface of the matrix, drying in the oven at 110 +/-5 ℃ for 6h, repeating the immersing and drying for 4 times;
and 4, placing the wire mesh in a muffle furnace, heating to 400 ℃ at a heating rate of 120 ℃/h, and preserving heat for 3h to obtain the surface coating of the wire mesh.
The surface coating is prepared and coated on the metal wire mesh, the surface coating is detected to have no crack or peeling, and after the ultrasonic vibrator is placed for 2 hours, the total loss of the surface coating is 14.1 percent after a thermal shock test (a sample is rapidly cooled in the air after being heated to 900 ℃ and is repeated for 10 times).
Example 6
The invention provides a preparation method of a surface coating of a wire mesh, which comprises the following steps:
step 1, weighing a sodium silicate solution and a sodium carboxymethylcellulose solution in a mass ratio of 3:1, and magnetically stirring for 30min to obtain a mixed solution, wherein the modulus of the sodium silicate solution is 3.25-3.35, and the concentration of the sodium carboxymethylcellulose solution is 3wt.%;
step 2, adding 49.50wt.% of spherical Al with the particle size of 35 μm into the continuously stirred mixed solution in sequence 2 O 3 30.00wt.% spherical Al having a particle size of 30 μm 2 O 3 1.50wt.% basalt fiber and 19.00wt.% TiO 2 Stirring for 1.5h, performing ultrasonic treatment in an ultrasonic oscillator for 1h, and standing for 12h to obtain a binder slurry;
step 3, immersing the metal wire mesh in a hydrochloric acid solution for ultrasonic treatment for 15min, taking out, washing with deionized water, standing for 15min, drying in an oven at 110 +/-5 ℃ for 2h, drying, putting in the bonding agent slurry, vacuumizing to-0.098 MPa, immersing for 0.5h to fully coat the slurry on the surface of the substrate, drying in the oven at 110 +/-5 ℃ for 6h, repeating the immersing and drying for 3 times;
and 4, placing the wire mesh in a muffle furnace, heating to 500 ℃ at a heating rate of 120 ℃/h, and preserving heat for 3h to obtain the surface coating of the wire mesh.
The surface coating is prepared and coated on the metal wire mesh, the surface coating is detected to have no crack or peeling, and after the ultrasonic vibrator is placed for 2 hours, the total loss of the surface coating is 8.8 percent after a thermal shock test (a sample is rapidly cooled in the air after being heated to 900 ℃ and is repeated for 10 times).
The invention also provides three comparative tests A, B, C, D for example 2, the test procedure is the same as in example 2, but the raw materials of the top coatings of the three comparative tests are different from the raw materials of the top coatings of example 2, and the total loss rate of the top coatings is determined after repeating 10 times by observing whether the coatings have cracks or peeling off and cooling the samples in air after heating the samples to 900 ℃, specifically as shown in table 1:
TABLE 1
Figure SMS_1
The results in table 1 show that in comparative test a, the fibrous skeleton is absent and the coating has an excessively high drying shrinkage, resulting in cracking and peeling.
In comparative test B, titanium dioxide and alumina can form proper particle size distribution, and the binding force between the coating lacking titanium dioxide and the wire mesh is insufficient.
In the comparative test C, during the sintering process, alumina is lacked, and only the titanium dioxide powder is difficult to completely fill the gaps between the basalt fiber frameworks, so that the bonding strength is reduced.
The total loss rate of the surface coating in example 2 provided by the invention is 0.9%, because during dipping, a concentration gradient exists at the edge of the wire mesh, and substances at the edge are unevenly distributed after multiple dipping, so that a small amount of loss occurs at the edge, and the total loss rate in example 2 of the application is negligible compared with the loss rate of the surface coating in comparative experiment A, B, C.
While in comparative experiment D, it was used to support an SCR catalyst (V) 2 O 5 -WO 3 (MoO 3 )/TiO 2 ) The metal wire mesh surface coating contains groups similar to catalyst components, and all raw materials in the formula have synergistic effect, so that the bonding strength of the coating and the metal wire mesh is effectively improved; in comparison with example 2, where two tie layers were formed, the total loss was 1.2%.
Data for the topcoats prepared in examples 1-6 provided by the present invention, and comparative run A, B, C, D are shown in table 2:
TABLE 2
Figure SMS_2
The surface coatings prepared in examples 1 to 6 were all free from cracks, peeling, and strong in adhesion to the wire mesh.
Due to the difference of physical and chemical properties of the metal material and the binding agent, the problems of catalyst peeling and the like caused by the performance reduction of binding strength, durability and the like easily occur in the preparation and use processes of the metal wire mesh load, so that the use of the catalytic denitration equipment is failed. The preparation method of the surface coating of the metal wire mesh provided by the invention is simple to operate, the bonding strength and durability of the catalyst and the metal wire mesh are obviously improved, the use efficiency of the catalyst is improved, the catalyst is convenient to attach to the surfaces of substrates with various geometric shapes, the requirements of various catalytic environments are met, the application range of the catalyst is expanded, and the carrier coating is a strong-adaptability coating, can be suitable for the surface geometric shapes with more complex metal wire meshes under most working conditions, the bonding condition of the metal wire mesh and the SCR catalyst is improved, the catalytic efficiency is improved, and the service life is prolonged.
In addition, because the metal wire mesh carrier is used, the metal wire mesh carrier is not a ceramic carrier, the production cost is greatly saved, the market competitiveness is realized, and the method is suitable for industrial production.
Other alternative embodiments of the invention will not be described in detail herein.
While embodiments of the invention have been described above, it is not limited to the applications set forth in the description and the embodiments, which are fully applicable in various fields of endeavor to which the invention pertains, and further modifications may readily be made by those skilled in the art, it being understood that the invention is not limited to the details shown and described herein without departing from the general concept defined by the appended claims and their equivalents.

Claims (5)

1. The surface coating of the metal wire mesh is characterized by comprising the following raw materials:
sodium silicate solution, sodium carboxymethylcellulose solution, aluminum oxide, titanium dioxide and basalt fiber;
wherein the aluminum oxide, the titanium dioxide and the basalt fiber are dissolved in a mixed solution prepared from the sodium silicate solution and the sodium carboxymethyl cellulose solution;
the mass fractions of the aluminum oxide, the titanium dioxide and the basalt fiber in the mixed solution are respectively 70-85wt.%, 15-20wt.% and 1-2wt.%;
the mass ratio of the sodium silicate solution to the sodium carboxymethyl cellulose solution is 3:1;
the particle size of the aluminum oxide is 15-50 mu m, the particle size of the titanium dioxide is 100-300 nm, the diameter of the basalt fiber is less than 10 mu m, and the length-diameter ratio of the basalt fiber is 8:1.
2. A method for preparing a surface coating of a wire-net according to claim 1, characterized by the steps of:
mixing a sodium silicate solution and a sodium carboxymethyl cellulose solution to obtain a mixed solution;
adding aluminum oxide, basalt fibers and titanium dioxide into the mixed solution, and stirring to obtain a binder slurry;
placing the acid-washed metal wire mesh in the bonding agent slurry, and repeatedly dipping and drying in a vacuum environment;
sintering the metal wire mesh to obtain a surface coating coated on the metal wire mesh;
adding aluminum oxide, basalt fibers and titanium dioxide into the mixed solution, and stirring to obtain a binder slurry, wherein the binder slurry specifically comprises:
adding 70-85wt.% of spherical aluminum oxide, 1-2wt.% of basalt fiber and 15-20wt.% of titanium dioxide into the mixed solution in sequence, and stirring for 1.5h;
and after stirring, carrying out ultrasonic treatment in an ultrasonic oscillator for 1h, and standing for 12h to obtain the binder slurry.
3. The method of preparing a surface coating of a wire mesh according to claim 2, wherein the mass ratio of the sodium silicate solution to the sodium carboxymethyl cellulose solution is 3:1, the sodium silicate solution modulus is 3.25-3.35, and the sodium carboxymethyl cellulose solution concentration is 3wt.%.
4. The method of preparing a surface coating for a wire-mesh screen of claim 2, wherein the steps of placing the acid-washed wire-mesh screen in the binder slurry, and repeatedly dipping and drying in a vacuum environment comprise:
immersing the metal wire mesh in an acid solution for ultrasonic treatment, washing and drying;
and placing the acid-washed wire mesh into the bonding agent slurry, vacuumizing to-0.098 MPa, soaking for 0.5h, drying at 100-120 ℃ for 6-10h, and repeating soaking and drying for 2-4 times.
5. The method of claim 2, wherein sintering the wire mesh to obtain the surface coating applied to the wire mesh comprises:
and (3) putting the wire mesh into a muffle furnace, heating to 400-600 ℃ at a heating rate of 120 ℃/h, and preserving heat for 1-3h to obtain the surface coating coated on the wire mesh.
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