CN110590349B

CN110590349B - Low-heat-conduction high-temperature furnace lining material and preparation method thereof

Info

Publication number: CN110590349B
Application number: CN201910980031.0A
Authority: CN
Inventors: 魏晶; 何新平; 段斌文; 胡鹏; 崔晓军; 刘�东; 路文; 郝明海
Original assignee: Beijing Zhonghuan Xinhui Technology Co ltd
Current assignee: Beijing Zhonghuan Xinhui Technology Co ltd
Priority date: 2019-10-15
Filing date: 2019-10-15
Publication date: 2021-10-08
Anticipated expiration: 2039-10-15
Also published as: CN110590349A

Abstract

Discloses a furnace lining material and a preparation method thereof, comprising the following steps: mixing the alumina mixture and amorphous silica to form a mullite precursor mixture; modifying the surface of the zirconium dioxide and the zirconium dioxide by using polyethylene glycol; mixing the acrylic acid mixed solution with the acrylic acid mixed solution to obtain slurry; in-situ polymerization to form gel; demoulding and drying to obtain a furnace lining green body; sintering the furnace lining green body, and cooling to obtain the furnace lining material. The heat conductivity coefficient at room temperature and the high-temperature rupture strength of the furnace lining material are both higher than those of the similar high-temperature furnace lining materials in the prior art.

Description

Low-heat-conduction high-temperature furnace lining material and preparation method thereof

Technical Field

The invention belongs to the technical field of refractory materials, relates to a furnace lining material and a preparation method thereof, and particularly relates to a low-heat-conduction high-temperature furnace lining material and a preparation method thereof.

Background

In thermal power equipment such as high-temperature furnaces and kilns, the lining material is a relatively common refractory material. The refractory material is inorganic non-metal material with refractoriness higher than 1500 degree, and can bear various physical and chemical changes and mechanical action in high temperature kiln as structural material. As the lining material, natural ore (such as chamotte, silica, magnesite, kaolin, dolomite, etc.) is mostly used as the raw material. More and more research is now focused on refractories made from certain industrial materials (e.g., high alumina cement) and synthetic materials (e.g., industrial alumina, silicon carbide, and synthetic mullite).

As a lining material, the material is usually in direct contact with a high-temperature kiln or carbon bricks, and is required to bear higher temperature when the kiln works, and the ideal lining material needs to have lower heat conductivity coefficient, so that the hot surface temperature of the carbon bricks can be reduced or the heat loss of the kiln can be reduced. On the other hand, it is also generally desirable that the lining material has excellent comprehensive physicochemical properties, especially relatively high-temperature rupture strength.

In the artificial synthetic material, the mullite ceramic is widely applied to various thermal engineering thermal devices such as high-temperature furnaces and kilns. The material has good chemical corrosion resistance, thermal shock resistance and high-temperature creep resistance; further, since polycrystalline transformation which causes a volume change does not occur in the entire crystallization temperature range, a ceramic material which has been recently favored has been used.

Chinese patent application CN103708814A discloses a preparation method of mullite-alumina porous ceramic, which comprises the steps of preparing emulsion from liquid polysiloxane and water under the action of an emulsifier, adding a dispersant and alumina powder into the emulsion, uniformly mixing to obtain slurry, then adding a siloxane cross-linking agent, uniformly mixing, and finally preparing the crack-free mullite-alumina porous ceramic by crosslinking, curing, drying and sintering the slurry; the density of the prepared mullite-alumina porous ceramic is 2.0-2.7 kg/m 3, the porosity is 29.9-42.8%, and the compressive strength is 99.2-152.1 MPa. However, the mullite-alumina porous ceramic prepared by the method has high density, low porosity and unsatisfactory heat-conducting property, and the high-temperature rupture strength of the material is not mentioned.

Chinese patent application CN103145444A discloses a preparation method of low-cost heat-preservation heat-insulation light porous mullite ceramic, which is characterized in that industrial mullite powder, starch, a thickening agent and a dispersing agent are stirred and mixed to obtain a mixture; adding water into the mixture, stirring, and performing ball milling to obtain stable ceramic slurry; adding a surfactant into the ceramic slurry, and stirring and foaming to obtain foam slurry; pouring the foam slurry into a mold, and heating and curing; demoulding and drying to obtain a porous ceramic blank; and sintering the porous ceramic blank in a high-temperature sintering furnace to obtain the porous mullite ceramic. The porosity and the heat conductivity coefficient can be adjusted by the raw material proportion, the solid content and the sintering temperature. The ceramic has a porosity of 80-86%, a density of 0.43-0.62 g/cm3, a thermal conductivity of 0.09-0.22W/(m.K), and a compressive strength of 1.0-5.0 MPa. The method improves the heat-conducting properties well, but the high-temperature bending resistance of the ceramic is not mentioned. However, in view of the above description, the porosity is too high, and thus the high temperature bending resistance is not yet expected to be satisfactory.

Therefore, a high-temperature furnace lining material with low thermal conductivity and high-temperature rupture strength and a preparation method thereof are urgently needed to be found.

Disclosure of Invention

The invention aims to provide a high-temperature furnace lining material with low heat conductivity coefficient and high-temperature rupture strength and a preparation method thereof.

In order to achieve the above object, in one aspect, the technical solution adopted by the present invention is as follows:

a preparation method of a furnace lining material is characterized by comprising the following steps:

mixing the alumina mixture and amorphous silica to form a mullite precursor mixture;

surface modifying the mullite precursor mixture with polyethylene glycol;

modifying the surface of the zirconium dioxide by using polyethylene glycol; and the number of the first and second groups,

obtaining an acrylic mixed solution;

mixing the acrylic mixed solution with the mullite precursor mixture subjected to surface modification and zirconium dioxide to obtain slurry;

the slurry is polymerized in situ to form gel;

demoulding and drying to obtain a furnace lining green body;

sintering the furnace lining green body, and cooling to obtain the furnace lining material.

The preparation method according to the present invention, wherein the alumina mixture is composed of α -alumina and γ -alumina.

The preparation method provided by the invention is characterized in that the average grain diameter D50 of the alpha-alumina is 1-5 μm.

Preferably, the average particle diameter D50 of the alpha-alumina is 1.5 to 4.5 μm; more preferably, the average particle diameter D50 of the alpha-alumina is 2 to 4 μm; and, most preferably, the alpha-alumina has an average particle diameter D50 of 2.5 to 3.5 μm.

In a specific embodiment, the alpha-alumina has an average particle size D50 of 3.1 μm.

The preparation method provided by the invention is characterized in that the average grain diameter D50 of the gamma-alumina is 60-100 μm.

Preferably, the average particle diameter D50 of the gamma-alumina is 65-95 μm; more preferably, the average particle diameter D50 of the gamma-alumina is 70 to 90 μm; and, most preferably, the gamma-alumina has an average particle size D50 of 75-85 μm.

In a specific embodiment, the gamma-alumina has an average particle size D50 of 82 μm.

The preparation method provided by the invention is characterized in that the weight ratio of the alpha-alumina to the gamma-alumina is 1 (2.2-3.8).

Preferably, the weight ratio of the alpha-alumina to the gamma-alumina is 1 (2.4-3.6); more preferably, the weight ratio of the alpha-alumina to the gamma-alumina is 1 (2.6-3.4), and; most preferably, the weight ratio of the alpha-alumina to the gamma-alumina is 1 (2.8-3.2).

In a specific embodiment, the weight ratio of the alpha-alumina to the gamma-alumina is 1: 3.

The preparation method of the invention is characterized in that the average particle diameter D50 of the amorphous silicon dioxide is 2-6 μm.

Preferably, the amorphous silica has an average particle diameter D50 of 2.5 to 5.5 μm; more preferably, the amorphous silica has an average particle diameter D50 of 3 to 5 μm, and; most preferably, the amorphous silica has an average particle size D50 of 3.5 to 4.5 μm.

In a particular embodiment, the amorphous silica has an average particle size D50 of 3.7 μm.

The preparation method provided by the invention is characterized in that the weight ratio of the alumina mixture to the amorphous silica is 1 (2.45-2.90).

Preferably, the weight ratio of the alumina mixture to the amorphous silica is 1 (2.48-2.80); more preferably, the weight ratio of the alumina mixture to the amorphous silica is 1 (2.51-2.70); and; most preferably, the weight ratio of the alumina mixture to the amorphous silica is 1 (2.53-2.60).

In a specific embodiment, the weight ratio of the alumina mixture to the amorphous silica is 1: 2.55.

The preparation method of the invention, wherein the average molecular weight Mn of the polyethylene glycol is 6000-10000 Dalton.

Preferably, the average molecular weight Mn of the polyethylene glycol is 6500-9500 daltons; more preferably, the average molecular weight Mn of the polyethylene glycol is 7000-9000 daltons; and, most preferably, the polyethylene glycol has an average molecular weight Mn of 7500 and 8500 daltons.

In a specific embodiment, the polyethylene glycol is selected from PEG 8000.

Advantageously, the polyethylene glycol is dispersed or dissolved in a suitable aqueous solvent.

The preparation method provided by the invention is characterized in that the addition amount of the polyethylene glycol is 0.4-1.0 wt% relative to the weight of the mullite precursor mixture.

Preferably, the polyethylene glycol is added in an amount of 0.55-0.85 wt% with respect to the weight of the mullite precursor mixture; more preferably, the polyethylene glycol is added in an amount of 0.6-0.8 wt% with respect to the weight of the mullite precursor mixture; and, most preferably, the polyethylene glycol is added in an amount of 0.65-0.75 wt% relative to the weight of the mullite precursor mixture.

In a particular embodiment, the polyethylene glycol is added in an amount of 0.7 wt% relative to the weight of the mullite precursor mixture.

According to the preparation method, the zirconium dioxide is added in an amount of 1.2-2.8 wt% relative to the weight of the mullite precursor mixture.

Preferably, the amount of zirconium dioxide added is between 1.4 and 2.6% by weight relative to the weight of the mullite precursor mixture; more preferably, the amount of zirconium dioxide added is between 1.6 and 2.4% by weight relative to the weight of the mullite precursor mixture; and, most preferably, zirconium dioxide is added in an amount of 1.8-2.2 wt% relative to the weight of the mullite precursor mixture.

In a specific embodiment, the amount of zirconia added is 2 wt% relative to the weight of the mullite precursor mixture.

The preparation method of the invention is characterized in that the addition amount of the polyethylene glycol is 0.4-1.0 wt% relative to the weight of the zirconium dioxide.

Preferably, the polyethylene glycol is added in an amount of 0.45 to 0.9 wt.%, relative to the weight of the zirconium dioxide mixture; more preferably, the polyethylene glycol is added in an amount of 0.5 to 0.8 wt% with respect to the weight of zirconium dioxide; and, most preferably, the polyethylene glycol is added in an amount of 0.55 to 0.7 wt% with respect to the weight of the zirconium dioxide.

In a specific embodiment, the polyethylene glycol is added in an amount of 0.6 wt% with respect to the weight of the zirconium dioxide.

According to the preparation method, the average grain diameter D50 of the zirconium dioxide is 5-9 μm.

Preferably, the zirconium dioxide has an average particle diameter D50 of 5.5 to 8.5 μm; more preferably, the zirconia has an average particle diameter D50 of 6 to 8 μm; and, most preferably, the zirconia has an average particle diameter D50 of 6.5 to 7.5 μm.

In a particular embodiment, the zirconium dioxide has an average particle diameter D50 of 6.7 μm.

According to the preparation method, the acrylic mixed solution comprises monomer methacrylamide and cross-linking agent polyethylene glycol dimethacrylate; the weight ratio of the two is (7-11) to 1.

Preferably, the acrylic mixed solution comprises monomer methacrylamide and cross-linking agent polyethylene glycol dimethacrylate; the weight ratio of the two is (7.5-10.5) to 1; more preferably, the acrylic mixed solution contains monomer methacrylamide and cross-linking agent polyethylene glycol dimethacrylate; the weight ratio of the two is (8-10) to 1; and, most preferably, the acrylic mixed liquor comprises monomer methacrylamide and cross-linking agent polyethylene glycol dimethacrylate; the weight ratio of the two is (8.5-9.5): 1.

In one embodiment, the acrylic mixed solution comprises monomer methacrylamide and cross-linking agent polyethylene glycol dimethacrylate; the weight ratio of the two is 9: 1.

The preparation method of the invention, wherein the average molecular weight Mn of the polyethylene glycol dimethacrylate is 250-.

Preferably, the average molecular weight Mn of the polyethylene glycol dimethacrylate is 270-; more preferably, the average molecular weight Mn of the polyethylene glycol dimethacrylate is 290-; and, most preferably, the average molecular weight Mn of the polyethylene glycol dimethacrylate is 310-.

In a more specific embodiment, the polyethylene glycol dimethacrylate has an average molecular weight Mn of 330.

According to the preparation method, the mass concentration of the acrylic mixed solution is 12-28 wt%.

Preferably, the mass concentration of the acrylic mixed solution is 14-26 wt%; more preferably, the mass concentration of the acrylic mixed solution is 16 to 24 wt%; and, most preferably, the mass concentration of the acrylic mixed liquid is 18 to 22 wt%.

In a specific embodiment, the acrylic mixed solution has a mass concentration of 20 wt%.

The preparation method provided by the invention is characterized in that the solid content of the slurry is 46-62%.

Preferably, the solids content of the slurry is 48-60%; more preferably, the solids content of the slurry is 50-58%; and, most preferably, the solids content of the slurry is 52-56%.

In a specific embodiment, the slurry has a solids content of 54%.

Advantageously, the slurry is adjusted to a pH of 6.0-9.0 using a suitable acid or base.

The preparation method according to the invention, wherein the in-situ polymerization is further added with an initiator and a catalyst.

Examples of the initiator include a peroxide initiator and an azo initiator. The catalyst is, for example, sulfuric acid, which is an acidic catalyst.

The preparation method according to the present invention, wherein the in-situ polymerization is carried out under conventional reaction conditions. These reaction conditions are well known to those skilled in the art.

The preparation method provided by the invention is characterized in that the sintering temperature is 1650-1700 ℃, and the heat preservation time is 1-6 h.

Preferably, the sintering temperature is 1675-; more preferably, the sintering temperature is 1700-1800 ℃, and the heat preservation time is 2-5 h; and, most preferably, the sintering temperature is 1725-1775 ℃, and the holding time is 2-4 h.

In a specific embodiment, the sintering temperature is 1750 ℃.

The preparation method according to the present invention, wherein the sintering further comprises a temperature raising step.

Advantageously, the furnace lining green body is heated up from room temperature to the sintering temperature according to a heating rate of 1-3 ℃/min.

On the other hand, the invention also provides the high-temperature furnace lining material which is prepared by the preparation method and has low heat conductivity coefficient and high-temperature rupture strength.

The invention has the beneficial technical effects that the room temperature heat conductivity coefficient and the high temperature rupture strength are higher than those of similar high temperature furnace lining materials in the prior art.

The results of the comparative tests are combined, so that the synergistic effect is fully demonstrated between the polyethylene glycol dimethacrylate and the polyethylene glycol, and the heat conductivity coefficient at room temperature and the flexural strength at high temperature are balanced and optimized.

Without wishing to be bound by any theory, the use of a combination of polyethylene glycol dimethacrylate and polyethylene glycol, and the specific proportions and particle sizes of the mullite precursor and zirconia raw materials, improves the micro-distribution and binding of the raw materials in the gel system, resulting in improved properties.

Detailed Description

It must be noted that, as used in this specification and the appended claims, the singular forms "a," "an," and "the" include both one and more than one (i.e., two, including two) unless the context clearly dictates otherwise.

Unless otherwise indicated, the numerical ranges in this disclosure are approximate and thus may include values outside of the stated ranges. The numerical ranges may be stated herein as from "about" one particular value, and/or to "about" another particular value. When such a range is expressed, another aspect includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent "about," it will be understood that the particular value forms another aspect. It will be further understood that the endpoints of each of the numerical ranges are significant both in relation to the other endpoint, and independently of the other endpoint.

Reference in the specification and concluding claims to parts by weight of a particular element or component in a composition or article refers to the weight relationship between that element or component and any other elements or components in the composition or article, expressed as parts by weight.

Unless specifically indicated to the contrary, or implied by the context or customary practice in the art, all parts and percentages referred to herein are by weight and the weight percentages of a component are based on the total weight of the composition or product in which it is included.

References to "comprising," "including," "having," and similar terms in this specification are not intended to exclude the presence of any optional components, steps or procedures, whether or not any optional components, steps or procedures are specifically disclosed. In order to avoid any doubt, all methods claimed through use of the term "comprising" may include one or more additional steps, apparatus parts or components and/or materials unless stated to the contrary. In contrast, the term "consisting of … …" excludes any component, step, or procedure not specifically recited or recited. Unless otherwise specified, the term "or" refers to the listed members individually as well as in any combination.

Furthermore, the contents of any referenced patent or non-patent document in this application are incorporated by reference in their entirety, especially with respect to definitions disclosed in the art (where not inconsistent with any definitions specifically provided herein) and general knowledge.

In the present invention, parts are parts by weight unless otherwise indicated, temperatures are indicated in ° c or at ambient temperature, and pressures are at or near atmospheric. There are many variations and combinations of reaction conditions (e.g., component concentrations, desired solvents, solvent mixtures, temperatures, pressures, and other reaction ranges) and conditions that can be used to optimize the purity and yield of the product obtained by the process. Only reasonable routine experimentation will be required to optimize such process conditions.

Example 1

Alpha-alumina having an average particle diameter D50 of 3.1 μm and gamma-alumina having an average particle diameter D50 of 82 μm were weighed in a weight ratio of 1:3, and added to a mixing cylinder to be uniformly mixed to obtain an alumina mixture. Amorphous silica having an average particle size D50 of 3.7 μm was weighed in a weight ratio of 1:2.55 to the alumina mixture, and uniformly mixed with the alumina mixture to obtain a mullite precursor mixture. Polyethylene glycol PEG8000 was added as a 15% ethanol solution at a loading of 0.7 wt% based on the weight of the mullite precursor mixture. After the addition was completed, the mixture was stirred at 3000rpm for 5min, thereby obtaining a surface-modified mullite precursor mixture. Monomer methacrylamide (MAM) and cross-linking agent polyethylene glycol dimethacrylate (PEGDMA, average molecular weight Mn 330) were mixed with deionized water at a weight ratio of 9:1 to make a 20 wt% mixture. And then adding the mullite powder into a mixing cylinder, fully mixing the mullite powder with the surface-modified mullite precursor mixture, and uniformly dispersing to obtain slurry. Further, zirconium dioxide having an average particle diameter D50 of 6.7 μm was weighed in an amount of 2 wt% relative to the mullite precursor mixture, while PEG8000 was added in an amount of 0.6 wt% and mixed uniformly to obtain a surface-modified zirconium oxide dispersion; and adding the mixture into a mixing cylinder, uniformly mixing with the slurry to obtain slurry with the solid content of 54%, and adjusting the pH value to 8.2. After mechanical foaming, the slurry is added with initiator ammonium persulfate accounting for 0.5 wt% of the weight of the slurry and catalyst accounting for 0.2 wt% of the weight of the slurry in sequence, and then the slurry is quickly poured into a PTFE (polytetrafluoroethylene) mould to undergo in-situ polymerization at the temperature of 55 ℃ to form gel. And demolding and drying to obtain the furnace lining green body. And (3) heating the furnace lining blank from room temperature to 1750 ℃ according to the heating rate of 2.5 ℃/min, preserving heat for 3 hours at the temperature, and naturally cooling to obtain the high-temperature furnace lining.

Comparative example 1

Otherwise, as in example 1, PEGDMA was replaced with an equal amount of MBAM.

Comparative example 2

Other conditions were the same as in example 1, except that both of the PEG8000 additions were replaced with CMC 1000.

Comparative example 3

The other conditions were the same as in example 1, except that no PEG8000 was added.

Performance testing

Measuring the thermal conductivity coefficient (unit is W/mK) of the sample by using a laser thermal conductivity meter Flashline 5000 at room temperature (25 ℃); and, the room temperature thermal conductivity and the high temperature (1200 ℃ C.) rupture strength (in MPa) of the high temperature furnace lining samples obtained in example 1 and comparative examples 1 to 3 were measured according to the national standard GB/T3002-2004.

The results are shown in Table 1.

TABLE 1

Sample (I)	Coefficient of heat conductivity at room temperature	High temperature rupture strength
			Example 1	0.17	15.2
Comparative example 1	0.34	11.8
			Comparative example 2	0.29	12.3
Comparative example 3	0.45	9.6

As a result, it was found that the high temperature furnace lining material of example 1 of the present application has both a low thermal conductivity and a high temperature rupture strength as compared with those of comparative examples 1 to 3. And the room temperature thermal conductivity and the high temperature rupture strength are higher than those of similar high temperature furnace lining materials in the prior art.

On the other hand, the thermal conductivity at room temperature and the high-temperature folding strength are obviously deteriorated after the methylene bisacrylamide is used for replacing in the comparative example 1; comparative example 2 the above-mentioned performance parameters also deteriorate significantly after the replacement with carboxymethylcellulose. In combination with the blank test of comparative example 3, it is fully demonstrated that the combination of PEGDMA and PEG8000 provides a synergistic effect, which together balances and optimizes the thermal conductivity at room temperature and the flexural strength at high temperature.

Without wishing to be bound by any theory, the use of PEGDMA in combination with PEG8000 and the specific proportions and particle sizes of the mullite precursor and zirconia starting material improves the micro-distribution and binding of the starting materials in the gel system, resulting in improved performance.

It should be understood that the detailed description of the invention is merely illustrative of the spirit and principles of the invention and is not intended to limit the scope of the invention. Furthermore, it should be understood that various changes, substitutions, deletions, modifications or adjustments may be made by those skilled in the art after reading the disclosure of the present invention, and such equivalents are also within the scope of the invention as defined in the appended claims.

Claims

1. A preparation method of a furnace lining material is characterized by comprising the following steps:

surface modifying the mullite precursor mixture with polyethylene glycol;

obtaining an acrylic mixed solution;

the slurry is polymerized in situ to form gel;

demoulding and drying to obtain a furnace lining green body;

sintering the furnace lining green body, and cooling to obtain a furnace lining material;

wherein the content of the first and second substances,

the alumina mixture consists of alpha-alumina and gamma-alumina;

the acrylic mixed solution comprises monomer methacrylamide and cross-linking agent polyethylene glycol dimethacrylate; the weight ratio of the two is (7-11) to 1;

the average molecular weight Mn of the polyethylene glycol dimethacrylate is 250-400.

2. The production method according to claim 1,

the average grain diameter D50 of the alpha-alumina is 1-5 μm;

and/or the presence of a gas in the gas,

the average grain diameter D50 of the gamma-alumina is 60-100 μm;

and/or the presence of a gas in the gas,

the average particle diameter D50 of the amorphous silicon dioxide is 2-6 μm;

and/or the presence of a gas in the gas,

the zirconium dioxide has an average particle diameter D50 of 5 to 9 μm.

3. The production method according to claim 1,

the weight ratio of the alpha-alumina to the gamma-alumina is 1 (2.2-3.8);

and/or the presence of a gas in the gas,

the weight ratio of the alumina mixture to the amorphous silica is 1 (2.45-2.90);

and/or the presence of a gas in the gas,

the amount of zirconium dioxide added is between 1.2 and 2.8% by weight with respect to the weight of the mullite precursor mixture.

4. The production method according to claim 1,

the average molecular weight Mn of the polyethylene glycol is 6000-10000 dalton;

and/or the presence of a gas in the gas,

the addition amount of the polyethylene glycol is 0.4-1.0 wt% relative to the weight of the mullite precursor mixture;

and/or the presence of a gas in the gas,

the addition amount of the polyethylene glycol is 0.4-1.0 wt% relative to the weight of zirconium dioxide.

5. The production method according to claim 1,

the solid content of the slurry is 46-62%.

6. The production method according to claim 1,

the sintering temperature is 1650-;

and/or the presence of a gas in the gas,

the sintering further comprises a temperature raising step.

7. A lining material obtained by the production method according to any one of claims 1 to 6.