A high-bending-resistance waste porcelain-based high-temperature resistant material and its preparation method and application

Abstract

The present invention belongs to the field of high temperature resistant technology, and specifically relates to a high-bending waste porcelain-based high temperature resistant material and its preparation method and application. The high temperature resistant material is made of the following raw materials by weight: 0-10wt.% kaolin, 0-20wt.% potassium feldspar, 4-10wt.% silica sol, and the remainder is waste 95 ceramics, and the content of the kaolin and potassium feldspar is not 0wt.%; the waste 95 ceramics is composed of powders of three particle sizes a, b, and c mixed in a weight ratio of 35:30:25, wherein 250μm>a≥120μm, 120μm>b≥75μm, and c<75μm. The high temperature resistant material has high mechanical strength and can be used in high temperature and high strength environments. The present invention realizes the resource recycling and reuse of industrial solid waste, can reduce environmental pollution, and can obtain high economic value under low cost conditions to meet the needs of the industry.

Description

Technical Field

[0001] The invention belongs to the technical field of high temperature resistance, and in particular relates to a high-bend resistance waste porcelain-based high temperature resistant material and a preparation method and application thereof. Background Art

[0002] Refractory materials generally refer to inorganic non-metallic materials with a refractoriness above 1580°C, including natural ores and various products made through certain processes according to purpose requirements. They have certain high-temperature mechanical properties and good volume stability, and are essential materials for various high-temperature equipment.

[0003] Due to the rapid development of the ceramic industry, the amount of non-degradable waste generated during the manufacturing and use process has gradually increased, but the vast majority is landfilled and few discarded ceramics can be recycled.

[0004] 95 ceramics refer to ceramics with an alumina content of 95%. They have low dielectric loss and are widely used in electronics and electrical appliances. Waste 95 ceramics contain a large amount of alumina and have the advantages of heat resistance, high temperature resistance and high strength. Recycling and utilizing waste 95 ceramics is a major challenge facing the development of green materials.

[0005] Rui Wang et al. [Rui W, Xianjie L, Haichao W, et al. Study on phase behavior and mechanical properties of high temperature resistant materials prepared from waste electric porcelain [J]. Ceramics International, 2023, 49 (7): 11537-11543.] used waste electric porcelain of different particle sizes (60-80wt.%), flint and dolomite as raw materials, and obtained refractory materials with better comprehensive performance after sintering at 1250°C. The results showed that the highest flexural strength of the prepared sample was 32.83MPa, and the volume density and open porosity of the sample were 2.21g / cm3 and 3.27%, respectively. However, at the temperature and pressure used, the performance of the prepared refractory material needs to be improved.

[0006] Patent CN115710138A discloses a method for preparing high-temperature resistant lightweight heat-insulating materials from waste electrical porcelain, using waste electrical porcelain, bauxite and clay as raw materials, but the materials need to be naturally air-dried, which takes a long time. Patent CN115745585A discloses a method for preparing low-aluminum mullite refractory bricks from waste electrical porcelain, using waste electrical porcelain, water glass solution, aluminum ash and clay as raw materials, but the preparation pressure is relatively high, and the flexural and compressive strengths of the prepared materials are relatively low.

[0007] The inventor of this patent's earlier paper "Preparation of unfired high-temperature resistant materials using waste electrical porcelain and research on their properties [D]. China University of Geosciences (Beijing), 2020." studied the effects of adding aluminum ash and alumina clinker fine powder on the performance of high-temperature resistant materials prepared from waste electrical porcelain, but the preparation method required a relatively high preparation pressure, the prepared samples had low flexural and compressive strengths, and additional alumina clinker fine powder was added.

[0008] Therefore, on the basis of existing research, how to further improve the refractory formula and preparation method and achieve a higher utilization rate of waste 95 ceramics is a technical problem to be solved. Summary of the invention

[0009] In order to solve the above technical problems, the present invention first provides a high-bend-resistance waste porcelain-based high-temperature resistant material.

[0010] The technical solution adopted by the present invention is:

[0011] A high-bending-resistance waste porcelain-based high-temperature resistant material is made of the following raw materials in weight proportion: 0-10wt.% of kaolin, 0-20wt.% of potassium feldspar, 4-10wt.% of silica sol, and the remainder is waste 95 ceramics, and the content of kaolin and potassium feldspar is not 0wt%; the waste 95 ceramics are composed of powders of three particle sizes of a, b, and c, which are mixed in a weight ratio of 35:30:20, wherein 250μm>a≥120μm, 120μm>b≥75μm, and c<75μm.

[0012] Preferably, the high temperature resistant material is made of the following raw materials in weight content: 10wt.% kaolin, 15wt.% potassium feldspar, 8wt.% silica sol, and the remainder is waste 95 ceramics; the waste 95 ceramics are composed of powders of three particle sizes of a, b, and c mixed in a weight ratio of 35:30:20, wherein 250μm>a≥120μm, 120μm>b≥75μm, and c<75μm.

[0013] Preferably, the waste 95 ceramics include Al2O3 and SiO2 components, and the Al2O3 content is higher than 70wt.%, and the SiO2 content is between 8 and 20wt.%.

[0014] Preferably, the average particle size of the kaolin powder is 600 μm, and the average particle size of the potassium feldspar powder is 600 μm.

[0015] Preferably, the silica sol has a silicon dioxide content of 30 wt.% and an average particle size of 10 to 20 nm.

[0016] The present invention further provides a method for preparing the above-mentioned high-bend-resistant waste porcelain-based high-temperature resistant material, comprising the following steps:

[0017] S1. According to the designed ratio, weigh and obtain the required kaolin powder, potassium feldspar powder and waste 95 ceramic powder and mix them, add 4 to 10wt.% of the total mass of the system as a silica sol binder, and stir the mixed powder to obtain a slurry;

[0018] S2. Pour the slurry into a mold, maintain the pressure at 8 to 20 MPa for 60 to 180 seconds, take it out after pressing, and dry it in a drying oven at 100 ° C for 6 to 24 hours;

[0019] S3. The dried block is subjected to high-temperature sintering, heated to 800°C at a heating rate of 10°C / min, then heated to 1000°C at a heating rate of 5°C / min, kept warm for 30 minutes, then continued to be heated to a sintering temperature of 1100-1400°C at a heating rate of 5°C / min, kept warm for 120-240 minutes, and finally cooled to 800°C at a cooling rate of 5°C / min, and then cooled with the furnace to obtain the desired high-bend-resistant waste porcelain-based high-temperature resistant material.

[0020] The present invention also provides a use of the above-mentioned high-bend-resistance waste porcelain-based high-temperature resistant material as a building material.

[0021] The beneficial effects of the present invention are:

[0022] The present invention uses waste 95 ceramics as the main raw material to prepare refractory materials, which solves the problem of recycling 95 ceramic solid waste on the one hand, and saves mineral resources and reduces consumption on the other hand.

[0023] The potassium feldspar added in the present invention will produce a liquid phase to fill pores at high temperature, thereby improving the density of the product and promoting the growth of mullite to enhance its strength; kaolin increases the plasticity of the green body, making it less likely to lose shape and deform; and silica sol used as a binder can increase the demoulding strength of the green body and increase the high-temperature volume stability.

[0024] The refractory material prepared by the present invention can be used under high temperature conditions due to its high mechanical strength. In a high temperature and high strength environment, it can serve as a supporting component, such as the load-bearing and pressure-bearing components of a kiln, etc.

[0025] The present invention realizes the resource recovery and reuse of industrial solid waste, can reduce environmental pollution, and can obtain high economic value at low cost, thus meeting the needs of the industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is the linear change rate and burning loss rate of S2 sample sintered at different sintering temperatures.

[0027] Figure 2 Analysis of apparent porosity and bulk density of S2 samples at different temperatures.

[0028] Figure 3 XRD spectra of S2 samples at different sintering temperatures.

[0029] Figure 4 is the flexural strength of S2 samples at different sintering temperatures.

[0030] Figure 5 SEM images of S2 samples sintered at different temperatures.

[0031] Figure 6 Linear shrinkage and loss on ignition rate of high temperature resistant materials sintered with different potassium feldspar contents.

[0032] Figure 7 The bulk density and apparent porosity of high temperature resistant materials sintered with different potassium feldspar contents.

[0033] Figure 8 XRD spectra of samples with different potassium feldspar contents.

[0034] Fig. 9 is the flexural strength of samples with different potassium feldspar contents

[0035] Fig.10 SEM images of samples with different potassium feldspar contents. DETAILED DESCRIPTION

[0036] For ease of understanding, the technical solution of the present invention is described in more detail below in conjunction with embodiments.

[0037] In the present invention, according to the national standard GB / T 3810.3-2016, the boiling method and the Archimedes drainage method are used to measure the open and closed porosity of the sample by relying on a density balance. According to the national standard GB / T 38978-2020, the three-point bending method is used to perform compression and flexural tests on the fired sample using a universal material testing machine. See Table 1 for some of the instruments used.

[0038] Table 1 Experimental instruments and equipment

[0039]

[0040] Example 1

[0041] Kaolin (average particle size 600 μm, Hebei Province, China), potassium feldspar (average particle size 600 μm, Shandong Province, China), and waste 95 ceramics were selected as raw materials, and silica sol (Henan Jieyang New Materials Co., Ltd.) was used as a binder to prepare high-bend-resistance waste ceramic-based high-temperature resistant materials.

[0042] The composition of the waste 95 ceramics is shown in Table 2 below:

[0043] Table 2 Chemical composition of waste 95 ceramics / wt.%

[0044]

[0045] The preparation method is as follows:

[0046] 1) Weigh the raw materials according to the required proportions and mix them to make a slurry. The kaolin content is 0-10wt% (not 0), the potassium feldspar is 0-20wt% (not 0), the silica sol is 4-10wt%, and the rest is waste 95 ceramics. The waste 95 ceramics are ground into powders of three particle sizes a, b, and c, and mixed in a weight ratio of a:b:c=35:30:25, wherein 250μm>a≥120μm, 120μm>b≥75μm, and c<75μm.

[0047] In this example, samples were prepared according to the formula in Table 3 for subsequent experiments.

[0048] Table 3 Sample formula / wt.%

[0049]

[0050] 2) The obtained slurry was pressed into rectangular blocks (45 mm×6 mm×6 mm) in a mold at a pressure of 10 MPa by semi-dry pressing method for 90 seconds. The blocks were taken out and placed in a drying oven at 100° C. for drying for 12 hours.

[0051] 3) High temperature sintering, sintering system: heat to 800°C at a heating rate of 10°C / min, then heat to 1000°C at a heating rate of 5°C / min, keep warm for 30 minutes, continue to heat to 1100-1400°C at a heating rate of 5°C / min, keep warm for 180 minutes, finally cool to 800°C at a cooling rate of 5°C / min, and then cool naturally to obtain the required high-bend-resistant waste porcelain-based high-temperature resistant material.

[0052] Example 2

[0053] Effect of different sintering temperatures on materials

[0054] Using the proportion of sample S2 in Example 1, the pressed samples were sintered at 1100° C., 1200° C., 1300° C., and 1400° C., respectively. No obvious cracks were found on the surfaces of all the sintered samples.

[0055] The linear change rate and burning loss rate of S2 samples at different sintering temperatures are shown in Figure 2. Figure 1 As shown, when the temperature range is 1100℃~1400℃, the burning loss rate of the sample is maintained between 1.21% and 1.44%, and the line change rate is between 0.42% and 0.6%. There is no overall change within the temperature span of 300℃.

[0056] The apparent porosity and bulk density of S2 samples at different temperatures are analyzed as follows: Figure 2 As shown in the figure, with the increase of temperature, the open pores of the sample first decrease and then increase, reaching the lowest value at 1300℃. The main reason is that potassium feldspar and other low melting point components in the green body fill the pores with liquid phase at high temperature. At the same time, liquid phase sintering will cause the material to shrink, resulting in volume shrinkage of the sample, thereby increasing the volume density. The formation of secondary mullite leads to expansion, which increases the packing density. When the temperature is 1400℃, the glaze erodes the surface more, resulting in a lower smoothness of the eroded part and a larger open porosity.

[0057] The XRD spectra of S2 samples sintered at different temperatures are shown in Figure 2. Figure 3 As shown, with the increase of temperature, the mullite content increases and the crystallinity of Al2O3 tends to increase.

[0058] The flexural strength of S2 samples at different sintering temperatures is shown in Figure 4 As shown. The internal sintering degree of the sample sintered at 1100℃ is low, and the bonding between particles is not tight enough. The strength is mainly provided by the combined effect of partially melted low-melting point components and silica sol binder. The increase in temperature promotes the internal liquid phase sintering and internal crystal growth of the sample. Some interwoven microstructures appear in the melt and interstitial pores, which provide the toughening effect of particles or fibers for the fracture of the sample after cooling. When the temperature is 1400℃, combined with the XRD spectrum, it is speculated that the formation of secondary mullite makes the organizational structure of the product uneven, sintering is difficult, and volume expansion occurs during the sintering process, which is related to Figure 1 and Figure 2 consistent with the changes.

[0059] SEM images of S2 samples sintered at different temperatures are shown in Figure 2. Figure 5 As shown in Figure 2, the sample sintered at 1200℃ has a distinct pore structure with a pore size of 50-60μm ( Figure 5 a, b). When the temperature rises to 1300℃, the spherical particles disappear, and a large number of short rod-shaped mullite crystals are formed and embedded in the generated molten glass phase. The interwoven whiskers enhance the stability of the material structure and improve the mechanical properties ( Figure 5 In the middle (d, e), it is found that the number of pores in the sample decreases. This is because as the temperature increases, more glass phases are generated, and large pores merge with small pores. The erosion range of the melt in the sample sintered at 1400℃ is expanded. It can be seen that the whiskers are wrapped by the glass phase and there is agglomeration effect between fine powders, which is not conducive to the sintering densification of the sample and may reduce the mechanical properties of the material.

[0060] In summary, the sintering temperature of the present invention is controlled at a maximum of 1300° C., which has the best effect.

[0061] Example 3

[0062] Effect of potassium feldspar doping amount on materials

[0063] Since the amount of columnar mullite generated in the sintered sample is small at 1300℃, and the formation of secondary mullite at 1400℃ causes the sample volume expansion and flexural strength to decrease, an optimization analysis of the potassium feldspar addition amount at 1300℃ was carried out.

[0064] Select 0wt.%, 5wt.%, 10wt.%, 15wt.%, 20wt.% 5 groups of doping amount, the linear shrinkage and burning loss rate of high temperature resistant materials sintered with different potassium feldspar contents refer to Figure 6 . With the increase of potassium feldspar content, the size and mass of the sintered body are not significantly different from those of the unsintered body. In addition, there are no obvious cracks on the surface of all sintered samples. When the potassium feldspar content increases from 0wt.% to 20wt.%, the linear shrinkage increases from 0.15% to a maximum of 1.07% and then decreases to 0.63%. At the same time, the loss on ignition increases from 1.34% to a high of 1.61% and then decreases to 0.63%. Lower shrinkage and mass change are beneficial to control the pore size and shape of the sample.

[0065] The bulk density and apparent porosity of high temperature resistant materials sintered with different potassium feldspar contents are as follows Figure 7 As shown. With the increase of potassium feldspar content, the volume density of the sample first increases and then decreases, and the apparent porosity shows a downward trend. The reason for this phenomenon is that the increase in the amount of liquid phase of potassium feldspar at a higher sintering temperature leads to a decrease in liquid viscosity. The liquid phase fills into the pores to reduce the porosity and promote sintering. When the potassium feldspar content is higher than 10wt.% of the glaze, the glass phase content inside the sample is too high, causing the sample to expand slightly, and the volume density shows a downward trend. The higher the potassium feldspar content, the more obvious this phenomenon is.

[0066] The XRD spectra of samples with different potassium feldspar contents are shown in Figure 2. Figure 8 As shown in the figure, it is inferred from the spectrum that the sample crystal phases are mainly corundum and mullite. As the content of potassium feldspar increases, the content of mullite decreases relatively. The liquid phase produced by the melting of potassium feldspar may hinder the growth of mullite.

[0067] The flexural strength of samples with different potassium feldspar contents is as follows Fig. 9As shown. With the increase of potassium feldspar content, the flexural strength of the sample first increases, reaches a peak value and then decreases. When the potassium feldspar content is 15wt.% of the matrix, the highest flexural strength is 103.90MPa. When the potassium feldspar content is 0wt.%, the internal sintering degree of the sample is low, the bonding between the particles is not tight enough, and the strength is mainly provided by the partially molten low-melting point components. The increase in potassium feldspar content increases the internal liquid phase content during sintering of the sample and promotes the growth of internal crystals. Some interwoven microstructures appear in the melt and interstitial pores, providing toughening effects of particles or fibers when the sample breaks. However, when the potassium feldspar content is too high (20wt.%), there is too much glass phase inside the sample, and the low-melting point components are easy to aggregate.

[0068] SEM images of samples with different potassium feldspar contents are shown in Figure 2. Figure 5 As shown. The low-viscosity liquid phase produced by the decomposition of potassium feldspar can not only fill the pores to achieve high densification of the sample, but also accelerate mass transfer and crystal growth. Some interwoven microstructures appear in the melt and interstitial pores, providing the toughening effect of particles or fibers when the sample is broken. In addition, after sintering, the liquid phase cools to an amorphous solid, called an intercrystalline glass phase, which has metastability. Before metallization, alumina ceramics are always fired at a temperature far below the sintering temperature to weaken the organic contamination on the surface and release some processing stress. During this process, the metastable phase will crystallize, which will reduce the fracture strength of alumina ceramics.

[0069] In summary, with the increase of potassium feldspar content, the flexural strength of the sample first increases and then decreases. At a sintering temperature of 1300℃, the flexural strength of the material is as high as 103.90MPa, mainly due to the number of internal pores and the generation and distribution of glass phase. The room temperature flexural strength of the sample adopts the partial force method of the three-point method. The XRD results show that the physical phases are basically consistent. With the increase of potassium feldspar content, the generation of glass phase reduces the number of internal micropores and increases the mechanical strength. However, when the glass phase is too much, its fracture performance is reduced.

[0070] In repeated tests on each sample, it was found that the performance error was about 5%. On the whole, when the temperature was 1300°C and the mass content of potassium feldspar was 15wt.%, the material prepared by the present invention had good practical value of refractory materials and could be used as a supporting material under strong pressure.

[0071] Example 4

[0072] In order to further compare the performance of the material prepared by the present invention with the existing waste porcelain refractory materials, a group of comparative experiments were designed with reference to Table 4. It can be seen that the highest flexural strength of the present invention is 103.90 MPa.

[0073] Table 4 Example 1 formulation and flexural strength

[0074]

[0075] In Comparative Example 1, the sintering temperature and raw materials of the 8 groups of samples are the same as those of Example 1, except that the waste 95 ceramics are replaced by waste sanitary ceramics. The test results are shown in Table 5.

[0076] Table 5 Comparative Example 1 Formulation and Flexural Strength

[0077]

[0078] In Comparative Example 2, the sintering temperature and raw materials of the 8 groups of samples are the same as those of Example 1, except that the waste 95 ceramics are replaced by waste low-aluminum electric porcelain. The test results are shown in Table 6.

[0079] Table 6 Comparative Example 2 Formulation and Flexural Strength

[0080]

[0081] As can be seen from the experimental results, the high temperature resistant material prepared by the present invention has the best flexural strength. The present invention is a better method for preparing refractory materials for recycling waste 95 ceramics.

[0082] Example 5

[0083] Methyl cellulose is a common thickener and is often used to improve the strength of green bodies; zirconium oxide is used in composite materials to improve their fracture toughness, flexural strength, etc. The flexural strength of high temperature resistant materials without and with methyl cellulose and zirconium oxide is compared, and the results are shown in Tables 7 and 8.

[0084] Table 7 Experimental results of adding thickener (methyl cellulose)

[0085]

[0086] Table 8 Experimental results of adding zirconium oxide

[0087]

[0088] It can be seen that the addition of methyl cellulose and zirconium oxide does not significantly improve the performance of the high temperature resistant material, and will increase the cost expenditure. This shows that the high temperature resistant material formula provided by the present invention is an optimized formula, has good high temperature resistance, and can play a good high temperature resistance effect without adding additional additives.

[0089] The above implementation modes are only used to illustrate the technical solutions of the present invention, but not to limit the present invention. Although the present invention has been described in detail with reference to the above implementation modes, those skilled in the art should understand that any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A high-bend-resistance waste porcelain-based high-temperature resistant material, characterized in that: The high temperature resistant material is made of the following raw materials in weight content: kaolin: 0-10wt.%, potassium feldspar 0-20wt.%, silica sol: 4-10wt.%, and the remainder is waste 95 ceramics, and the content of kaolin and potassium feldspar is not 0wt%; the waste 95 ceramics are composed of powders of three particle sizes of a, b, and c mixed in a weight ratio of 35:30:25, wherein 250μm>a≥120μm, 120μm>b≥75μm, and c<75μm.

2. The high-bend-resistance waste porcelain-based high-temperature resistant material according to claim 1, characterized in that: The high temperature resistant material is made of the following raw materials in weight content: kaolin: 10wt.%, potassium feldspar 15wt.%, silica sol: 8wt.%, and the remainder is waste 95 ceramics; the waste 95 ceramics are composed of powders of three particle sizes of a, b, and c mixed in a weight ratio of 35:30:25, wherein 250μm>a≥120μm, 120μm>b≥75μm, and c<75μm.

3. The high-bend-resistance waste porcelain-based high-temperature resistant material according to claim 1, characterized in that: The waste 95 ceramics include Al2O3 and SiO2 components, and the Al2O3 content is higher than 70wt.%, and the SiO2 content is between 8wt.% and 20wt.%.

4. The high-bend-resistance waste porcelain-based high-temperature resistant material according to claim 1, characterized in that: The average particle size of the kaolin powder is 600 μm, and the average particle size of the potassium feldspar powder is 600 μm.

5. The high-bend-resistance waste porcelain-based high-temperature resistant material according to claim 1, characterized in that: The silica sol has a silicon dioxide content of 30 wt.% and an average particle size of 10-20 nm.

6. A method for preparing a high-bend-resistance waste porcelain-based high-temperature resistant material according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. According to the designed ratio, weigh and obtain the required kaolin powder, potassium feldspar powder and waste 95 ceramic powder and mix them, add 4 to 10wt.% of the total mass of the system as a silica sol binder, and stir the mixed powder to obtain a slurry; S2. Pour the slurry into a mold, maintain the pressure at 8 to 20 MPa for 60 to 180 seconds, take it out after pressing, and dry it in a drying oven at 100 ° C for 6 to 24 hours; S3. The dried block is subjected to high-temperature sintering, heated to 800°C at a heating rate of 10°C / min, then heated to 1000°C at a heating rate of 5°C / min, kept warm for 30 minutes, then continued to be heated to a sintering temperature of 1100-1400°C at a heating rate of 5°C / min, kept warm for 120-240 minutes, and finally cooled to 800°C at a cooling rate of 5°C / min, and then cooled with the furnace to obtain the desired high-bend-resistant waste porcelain-based high-temperature resistant material.

7. Use of a high-bend-resistance waste porcelain-based high-temperature resistant material according to any one of claims 1 to 5 as a building material.

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