Novel biological fermentation ultralight foamed ceramic material as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of porous ceramics, and particularly relates to a novel biological fermentation ultralight foamed ceramic material as well as a preparation method and application thereof. The novel biological fermentation ultralight foamed ceramic material is prepared from the following raw materials: a pore forming agent, a toughening aid and ceramic powder, wherein the pore-forming agent comprises flour, water, yeast powder, egg white liquid, vegetable oil, citric acid and ammonium bicarbonate. In the preparation process of the biological fermentation ultralight foamed ceramic new material, the raw materials in the pore-forming agent have a synergistic effect through a biological fermentation method, a chemical foaming decomposition method and a mechanical stirring method, so that the volume density of the obtained biological fermentation ultralight foamed ceramic new material is lower than 0.3 g / cm < 3 >, and the porosity is higher than 90%; and pores in the novel biological fermentation ultralight foamed ceramic material are uniform in size and distribution, and have the microscopic characteristics of good uniformity and stability.

Description

Technical Field

[0001] The invention belongs to the technical field of porous ceramics, and in particular relates to a new biological fermentation ultra-light foam ceramic material and a preparation method and application thereof. Background Art

[0002] Porous ceramics are a new type of ceramic material, made by high-temperature sintering, with a large number of pores that are interconnected or closed. According to the porosity, they can be divided into low porosity (porosity <40%), medium porosity (porosity 40% to 63%, also known as lightweight porous ceramic materials), and high porosity (porosity >63%, also known as ultra-lightweight porous ceramic materials). Porous ceramics have rich and evenly distributed micropores or pore structures, which give it many excellent physical and chemical properties, including high porosity, low volume density, large specific surface area and other structural characteristics; in addition, porous ceramics also exhibit unique high temperature resistance, corrosion resistance, high chemical stability and dimensional stability, can selectively penetrate liquid and gas media, and have good energy absorption and damping characteristics.

[0003] Ultra-light ceramic materials are usually composed of micro-nano porous structures, and these micropores and pores have a significant impact on the mechanical properties of the material. For example, factors such as the size, shape, and distribution density of the pores will directly affect the strength, hardness, and toughness of the material. Especially when applied over a large area, the uniformity and stability of these microscopic features become crucial, and precise control methods are required to ensure the performance consistency of each material block or part. Since the preparation process of ultra-light ceramics involves complex chemical reactions, heat treatments, and structural control steps, any slight changes or inconsistencies in the preparation process may lead to differences in the performance of the final product. Therefore, the stability and consistency of the preparation process are the key points and difficulties in ensuring the uniformity of material performance. However, most of the existing porous ceramic materials produced by fermentation technology have problems with pores of different sizes and uneven distribution, which greatly affects the application of porous ceramic materials.

[0004] For example, a Chinese patent with authorization announcement number CN103922784B discloses a method for preparing porous ceramics by low-temperature forming through microbial fermentation, comprising the following steps: taking 10% to 90% ceramic powder and 10% to 90% starch by volume, mixing them evenly to obtain a mixed powder; taking 0.5% to 5% yeast, 0.1% to 5% activator, and 90% to 99.5% distilled water by mass to obtain a fermentation solution; taking 60% to 85% of the mixed powder and 15% to 40% fermentation solution by volume, mixing them evenly to obtain a ceramic slurry; fermenting the ceramic slurry, and then freezing the ceramic slurry after the fermentation is completed; taking out the frozen ceramic slurry and drying it at low pressure to obtain a porous ceramic preform; and finally sintering at 1250 to 1700°C to obtain a porous ceramic with high porosity. The invention provides a method for preparing porous ceramics by low-temperature forming through microbial fermentation. The method generates CO2 through microbial fermentation to form pores, and then combines freeze-drying technology to fix the pores obtained through fermentation, so as to solve the problem of low porosity and obvious macroscopic defects of the currently prepared porous ceramics. However, the lattice arrangement of ceramic powder is relatively tight, and the density of ceramic powder is greater than that of starch-based substances. Therefore, during the fermentation process, the ceramic powder will slowly sink, and at the same time, the newly generated gas will be squeezed to make the gas float, resulting in different pore sizes and uneven distribution inside the ceramic slurry after freezing, resulting in poor uniformity and stability of the microscopic characteristics of the high-porosity porous ceramics finally obtained. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention aims to provide a new bio-fermented ultra-light foam ceramic material and its preparation method and application. In the preparation process of the new bio-fermented ultra-light foam ceramic material of the present invention, the raw materials in the pore-forming agent act synergistically through the bio-fermentation method, the chemical foaming decomposition method and the mechanical whipping method, so that the volume density of the obtained new bio-fermented ultra-light foam ceramic material is lower than 0.3g / cm 3 The porosity is higher than 90%, and the pore size inside the new bio-fermentation ultra-light foam ceramic material is uniform and evenly distributed, with good uniformity and stability in microscopic characteristics.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] A new bio-fermented ultra-light foam ceramic material comprises the following raw materials: a pore former, a toughening agent and ceramic powder; wherein the pore former comprises flour, yeast powder, egg white liquid, vegetable oil, water, citric acid and ammonium bicarbonate; and by weight, the raw materials specifically comprise: 100 parts of flour, 30-60 parts of water, 0.5-2 parts of yeast powder, 30-60 parts of egg white liquid, 5-10 parts of vegetable oil, 1-3 parts of citric acid, 3-6 parts of ammonium bicarbonate, 10-20 parts of toughening agent and 75-150 parts of ceramic powder.

[0008] In the preparation process of the new bio-fermentation ultra-light foam ceramic material of the present invention, the raw materials in the pore-forming agent have the following synergistic effects:

[0009] First, during the mixing process of the raw materials, citric acid (scientific name 2-hydroxypropane-1,2,3-tricarboxylic acid, molecular formula C6H8O7) can react with ammonium bicarbonate (NH4HCO3) in water to generate carbon dioxide gas. The reaction chemical equation is: C6H8O7+3NH4HCO3→(NH4)3C6H5O7+3H2O+3CO2↑. This reaction can produce abundant fine bubbles for the ceramic slurry. At the same time, during the mixing and beating process, the protein in the flour and egg white liquid can not only play a thickening role, but also wrap and retain a large number of tiny bubbles beaten into the ceramic slurry by stirring; it can also wrap the gases produced by the above-mentioned citric acid and other reactions in the foamed ceramic slurry to form the main body of the foamed ceramic slurry. Secondly, flour and the like can ferment and produce gas under the action of yeast powder, further providing abundant bubbles for ceramic materials, and the bubbles produced during fermentation can continuously provide support for ceramic powder with a tendency to sink, thereby preventing it from sinking and squeezing out the gas, and at the same time, it can avoid the situation in which the ceramic powder is mainly in the bottom layer and the flour remains in the upper layer in the green body after ceramic shaping, and finally the problem that the volume density of the bottom of the ceramic material is large and the pores in the middle and upper parts are large after sintering; and the egg white liquid can also form a protective film with the vegetable oil on the surface of the foam, thereby improving the surface tension of the foam and reducing the brittleness of the foam. At the same time, during the stirring process, the egg white liquid and the vegetable oil can also play a solidifying role, which can shape the foamed ceramic slurry, thereby further preventing the sinking of the ceramic powder and the floating of the foam during the fermentation or shaping process, thereby effectively avoiding the problem that the pores inside the obtained new ceramic material are of different sizes and uneven distribution.

[0010] Secondly, the excess ammonium bicarbonate will decompose during the heating process of the ceramic slurry (thermal decomposition temperature is about 30-60°C) to generate NH3, CO2 and H2O, which will further create bubbles for the ceramic slurry. This step also provides support for the ceramic powder to prevent it from sinking; and the product ammonium citrate will gradually decompose as the temperature rises at high temperatures (decomposition temperature is 185°C), and will also decompose into NH3, CO2 and H2O during the heating process of the blank, burning out and forming pores. At the same time, no metal ion impurities will remain in the new ceramic material to affect its refractoriness; in addition, during the heating process, the protein in the egg white liquid begins to slowly denature and solidify, so that the original foam and newly generated foam in the slurry can be effectively shaped, effectively improving the stability and consistency of the preparation process, thereby ensuring the uniformity of the performance of the ceramic material.

[0011] In summary, the present invention uses the synergistic effect of biological fermentation, chemical foaming decomposition and mechanical whipping to obtain a new bio-fermented ultra-light foam ceramic material with a volume density lower than 0.3 g / cm 3 The porosity is higher than 90%, and the new bio-fermentation ultra-light foam ceramic material has good microscopic characteristics of uniformity and stability.

[0012] Furthermore, the ceramic powder is alumina powder, zirconium oxide powder, quartz powder or hydroxyapatite.

[0013] The porous ceramic preparation methods in the prior art are all for a single, specific type of ceramic material, and can only prepare specific types of porous ceramics, while the preparation method provided by the present invention is universal, and different types of ultra-light foam ceramic materials can be prepared by only changing the ceramic powder. Depending on the different ceramic powders added (such as alumina, zirconium oxide, quartz, hydroxyapatite, etc.), different ultra-light foam ceramic materials can be prepared and applied to different fields, such as as an efficient and energy-saving lightweight heat-insulating furnace material, or as a catalyst carrier, filter material, and medical bone filling material, etc., which greatly broadens the scope of application of ultra-light foam ceramic materials.

[0014] Furthermore, the toughening aid is short-cut fiber cotton; the short-cut fiber cotton is synthetic fiber or natural fiber. The short-cut fiber cotton can play the role of toughening, crack prevention and burning loss pore formation.

[0015] Furthermore, in some preferred embodiments of the present invention, the chopped fiber cotton is preferably alumina fiber, zirconia fiber, quartz fiber, organic synthetic fiber (such as polypropylene fiber), bamboo fiber or cotton, etc.

[0016] The present invention also provides a method for preparing the above-mentioned bio-fermented ultra-light foam ceramic new material, which comprises stirring and mixing the raw materials evenly, and then injecting them into a mold for fermentation, wherein the fermentation temperature is 25 to 30° C. and the fermentation time is 30 to 60 minutes; the temperature is raised to 60 to 80° C. and kept warm for 12 to 24 hours until the ceramic slurry solidifies and the internal moisture evaporates to obtain a foam ceramic original dry blank; the foam ceramic original dry blank is sintered at 1100 to 1700° C. to obtain the bio-fermented ultra-light foam ceramic new material.

[0017] When preparing the new bio-fermented ultra-light foam ceramic material, the present invention ferments at 25-30°C for 30-60 minutes, which can make the fermentation process more fully proceed; keeping warm at 60-80°C for a period of time not only helps the excess ammonium bicarbonate to completely decompose to generate NH3, CO2 and H2O, and further generate bubbles for the foaming slurry; but also enables the egg white liquid to slowly denature in the process, thereby playing an effective solidification role, and then fixes the pores and shape of the ceramic material, and prevents it from collapsing.

[0018] Furthermore, the stirring speed is 100-300 rpm.

[0019] Stirring the ceramic raw materials at the above speed can stir the air into the ceramic slurry more evenly without causing uneven mixing problems; secondly, stirring within this speed range can thicken the flour and egg white liquid better, thereby achieving a better gas encapsulation effect.

[0020] Furthermore, the heating rate is 0.05-0.1°C / min; and the insulation time is 12-24h.

[0021] The invention slowly heats the temperature to 60-80°C at a heating rate of 0.05-0.1°C / min and keeps the temperature for a period of time, which not only allows the excess ammonium bicarbonate to be completely decomposed during the heating process, but also helps the egg white liquid to be slowly denatured during the process, so as to ensure the accuracy and consistency of the product during the formation process.

[0022] Furthermore, the original dry foam ceramic blank is placed in a high-temperature electric furnace, heated to 1100-1700°C at a heating rate of 1-2°C / min and kept warm for 2-6 hours to obtain a new bio-fermented ultra-light foam ceramic material.

[0023] The above slow heating process can ensure that all substances in the pore-forming agent can be completely decomposed during the preparation process, which helps to form a new ultra-light foam ceramic material with low volume density and high porosity. During the slow heating process, the product of ammonium citrate generated by the reaction of citric acid and ammonium bicarbonate in the pore-forming agent will begin to gradually decompose after the temperature reaches about 185°C; while the remaining substances in the pore-forming agent will begin to undergo dehydrogenation and carbonization reactions at about 250°C, and continue to carbonize during the subsequent gradual heating process; as the temperature rises to about 600-650°C, the remaining carbon begins to undergo oxidation reactions, and continues to oxidize during the slow heating process until the temperature reaches about 800°C, the carbon is completely oxidized, and the burnout pore-forming of the pore-forming agent is completed, and finally the volume density of the obtained bio-fermentation ultra-light foam ceramic new material is lower than 0.3g / cm 3 , porosity is higher than 90%.

[0024] Furthermore, when alumina powder is used as the ceramic powder, the foam ceramic raw blank is sintered at 1600-1700°C; when zirconium oxide powder is used as the ceramic powder, the foam ceramic raw blank is sintered at 1500-1600°C; when quartz powder is used as the ceramic powder, the foam ceramic raw blank is sintered at 1550-1650°C; when hydroxyapatite is used as the ceramic powder, the foam ceramic raw blank is sintered at 1100-1200°C.

[0025] Furthermore, the present invention also provides the use of the above-mentioned bio-fermentation ultra-light foam ceramic new material in the preparation of furnace materials, medical bone filling materials, catalyst carriers or filter materials.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. During the stirring and fermentation process of the ceramic raw materials of the existing fermented porous ceramic materials, the heavier ceramic powder is easy to sink, resulting in stratified aggregation of the ceramic raw materials (the ceramic powder is mostly distributed in the lower layer, while the other raw materials are distributed in the upper layer); at the same time, the foam is squeezed in this process and is easy to float, which makes the foam easy to burst and the gas in the foam is squeezed out; and this process will also cause the system to be unstable and easy to collapse, and it is difficult to maintain a fixed shape, which ultimately causes the pores and volume density of the ceramic material after the burn-out pore making to be uneven, and the product shape varies greatly, which ultimately affects the performance of the product. The present invention innovatively adds egg white liquid and vegetable oil to the pore-forming agent. The egg white liquid and flour can play a thickening role during the stirring process, and can beat tiny bubbles in the air into the slurry and wrap and retain them; and under continuous stirring, the egg white liquid and vegetable oil can form a protective film on the foam surface to reduce the brittleness of the foam, so that the gas in the foam can stably exist therein, and secondly, it can also play a solidifying role, fix the shape of the ceramic material after stirring, and avoid the collapse of the ceramic slurry; furthermore, the present invention also creatively adds citric acid and ammonium bicarbonate to the pore-forming agent, which not only enables the ceramic slurry to obtain richer foam, but also can provide support for the ceramic powder that has a tendency to sink during stirring, fermentation and heating in stages, so that the volume density of the finally obtained biological fermentation ultra-light foam ceramic new material is lower than 0.3g / cm 3 , porosity is higher than 90%, and has microscopic characteristics of good uniformity and stability.

[0028] 2. The preparation method provided by the present invention can prepare different types of ultra-light foam ceramic materials by changing the ceramic powder according to the needs, which has universal applicability and breaks the limitation that the porous ceramic preparation methods in the prior art are all for a single, specific type of ceramic material. Since the preparation method provided by the present invention can prepare different ultra-light foam ceramic materials by adding different ceramic powders, such as alumina, zirconium oxide, quartz, hydroxyapatite, etc., and then be applied to different fields, such as as an efficient and energy-saving lightweight thermal insulation furnace material, or as a catalyst carrier, filter material, and medical bone filling material, etc., the application scope of ceramic materials is greatly broadened.

[0029] 3. The raw materials used in the present invention are environmentally friendly green raw materials, such as flour, vegetable oil, etc., which are renewable resources. These raw materials are not only beneficial to environmental protection, but can also be quickly converted into high-quality ceramic materials through the simple preparation method of the present invention, which is conducive to commercial production and is expected to be applied in different fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a picture of the new bio-fermentation ultra-light foam ceramic material product prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0031] The technical solution of the present invention is described in detail below in conjunction with specific embodiments and their accompanying drawings. The embodiments recorded herein are specific embodiments of the present invention, which are used to illustrate the concept of the present invention; these descriptions are explanatory and exemplary and should not be construed as limitations on the embodiments of the present invention and the scope of protection of the present invention. In addition to the embodiments recorded herein, those skilled in the art can also adopt other obvious technical solutions based on the contents disclosed in the claims of this application and its specification, including technical solutions that adopt any obvious replacements and modifications to the embodiments recorded herein.

[0032] The reagents used in the present invention are all commonly used reagents and can be purchased from conventional reagent production and sales companies.

[0033] Example 1

[0034] The raw materials are weighed according to the following weight proportions: 100 parts of flour, 30 parts of water, 0.5 parts of yeast powder, 30 parts of egg white liquid, 5 parts of vegetable oil corn oil, 1 part of citric acid, 3 parts of ammonium bicarbonate, 10 parts of toughening agent alumina fiber (length 0.1-1 mm) and 75 parts of ceramic powder alumina powder (particle size 0.05-5 μm). The raw materials are stirred and mixed evenly at a stirring speed of 100 rpm, and then injected into a mold for fermentation at a fermentation temperature of 25°C for 30 minutes; then the temperature is raised to 60°C at a heating rate of 0.05°C / min, and the temperature is kept for 12 hours until the ceramic slurry is solidified and the internal water is completely evaporated to obtain a foam ceramic original dry blank; the foam ceramic original dry blank is placed in a high-temperature electric furnace, and the temperature is raised to 1650°C at a heating rate of 1°C / min and kept for 2-6 hours to obtain a new bio-fermented ultra-light foam ceramic material.

[0035] The obtained bio-fermentation ultra-light foam ceramic new material products are as follows Figure 1 shown.

[0036] Example 2

[0037] Weigh the raw materials according to the following weight proportions: 100 parts of flour, 60 parts of water, 2 parts of yeast powder, 60 parts of egg white liquid, 10 parts of vegetable oil soybean oil, 3 parts of citric acid, 6 parts of ammonium bicarbonate, 20 parts of toughening agent quartz fiber (length 0.1-1 mm) and 150 parts of ceramic powder quartz powder (particle size 0.05-5 μm). Stir and mix the raw materials evenly at a stirring speed of 300 rpm, then inject them into a mold for fermentation, the fermentation temperature is 30°C, and the fermentation time is 60 minutes; then heat it to 80°C at a heating rate of 0.1°C / min, keep it warm for 24 hours, until the ceramic slurry solidifies and the internal water evaporates completely, and obtains the original dry foam ceramic blank; the original dry foam ceramic blank is placed in a high-temperature electric furnace, heated to 1600°C at a heating rate of 2°C / min and kept warm for 2-6 hours, and a new bio-fermented ultra-light foam ceramic material is obtained.

[0038] Example 3

[0039] The raw materials are weighed according to the following weight proportions: 100 parts of flour, 40 parts of water, 1 part of yeast powder, 40 parts of egg white liquid, 7 parts of vegetable oil sunflower oil, 2 parts of citric acid, 6 parts of ammonium bicarbonate, 15 parts of toughening agent zirconia fiber (length 0.5mm) and 100 parts of ceramic powder yttria-stabilized cubic phase zirconia ultrafine powder (particle size 0.05-5μm). The raw materials are stirred and mixed evenly at a stirring speed of 200 rpm, and then injected into a mold for fermentation at a fermentation temperature of 25°C and a fermentation time of 40 minutes; then the temperature is raised to 65°C at a heating rate of 0.08°C / min, and the temperature is kept for 15h until the ceramic slurry is solidified and the internal water is completely evaporated to obtain the original dry foam ceramic blank; the original dry foam ceramic blank is placed in a high-temperature electric furnace, and the temperature is raised to 1550°C at a heating rate of 1.5°C / min and kept for 4h to obtain a new bio-fermented ultra-light foam ceramic material.

[0040] Example 4

[0041] The raw materials are weighed according to the following weight proportions: 100 parts of flour, 50 parts of water, 1.5 parts of yeast powder, 50 parts of egg white liquid, 8 parts of vegetable rapeseed oil, 2 parts of citric acid, 6 parts of ammonium bicarbonate, 15 parts of toughening agent bamboo fiber (length 0.1-1 mm) and 120 parts of ceramic powder hydroxyapatite (particle size 0.05-5 μm). The raw materials are stirred and mixed evenly at a stirring speed of 200 rpm, and then injected into a mold for fermentation at a fermentation temperature of 28°C for 50 minutes; then the temperature is raised to 75°C at a heating rate of 0.08°C / min, and the temperature is kept for 20 hours until the ceramic slurry is solidified and the internal water is completely evaporated to obtain the original dry foam ceramic blank; the original dry foam ceramic blank is placed in a high-temperature electric furnace, and the temperature is raised to 1150°C at a heating rate of 1.7°C / min and kept for 2-6 hours to obtain a new bio-fermented ultra-light foam ceramic material.

[0042] Comparative Example 1

[0043] Ultralight alumina foam ceramics were prepared by referring to the preparation method disclosed in paragraph

[0033] of the specification of Chinese patent application “An ultralight alumina foam ceramic and preparation method thereof” with publication number CN 104311118 A.

[0044] Comparative Example 2

[0045] Comparative Example 2 is similar to Example 1, except that the pore-forming agent consists of flour, water and yeast powder.

[0046] The raw materials are weighed according to the following weight proportions: 100 parts of flour, 30 parts of water, 0.5 parts of yeast powder, 10 parts of toughening agent alumina fiber (length 0.1-1 mm) and 75 parts of ceramic powder alumina powder (particle size 0.05-5 μm).

[0047] Comparative Example 3

[0048] Comparative Example 3 is similar to Example 1, except that no egg white liquid and vegetable oil are added to the pore-forming agent.

[0049] The raw materials were weighed according to the following weight proportions: 100 parts of flour, 30 parts of water, 0.5 parts of yeast powder, 1 part of citric acid, 3 parts of ammonium bicarbonate, 10 parts of alumina fibers (length 0.1-1 mm) as a toughening aid, and 75 parts of alumina powder (particle size 0.05-5 μm) as a ceramic powder.

[0050] Comparative Example 4

[0051] Comparative Example 4 is similar to Example 1, except that citric acid and ammonium bicarbonate are not added to the pore-forming agent.

[0052] The raw materials are weighed according to the following weight proportions: 100 parts of flour, 30 parts of water, 0.5 parts of yeast powder, 30 parts of egg white liquid, 5 parts of vegetable oil corn oil, 10 parts of toughening agent alumina fiber (length 0.1-1 mm) and 75 parts of ceramic powder alumina powder (particle size 0.05-5 μm).

[0053] Test Example: The performance of the new bio-fermented ultra-light foam ceramic materials prepared in each group of examples and comparative examples was tested. The specific test process is as follows:

[0054] 1. Bulk density

[0055] The test method is the weight method: the density of the new bio-fermented ultra-light foam ceramic material is determined by measuring its weight and macroscopic volume. The six sides of the new bio-fermented ultra-light foam ceramic material are ground flat into a rectangular parallelepiped, and its weight is measured using a balance. Then, a vernier caliper is used to measure the average length of its three mutually perpendicular edges to calculate the volume of the object, thereby calculating the volume density of the new bio-fermented ultra-light foam ceramic material.

[0056] Bulk density D 体 = weight m / volume V 总 , where volume V 总 Includes the openings and closed pores inside the material, that is, the volume V 总 It is the sum of the volume of the substance, open pores and closed pore volumes.

[0057] 2. Porosity

[0058] The porosity P is the true density D of the material. 真 Compared with the measured volume density D 体 The numerical comparison is obtained by theoretical calculation.

[0059] True density D 真 = weight m / volume V 真 , where volume V 真 Openings and closed pores inside the material are not included;

[0060] Bulk density D 体 =True density D 真 ×(1-porosity P), so porosity P = 1-bulk density D 体 / True density D 真 .

[0061] Note that the porosity mentioned above is the total porosity, which refers to the percentage of the volume of the total pores in the sample to the total volume of the sample, which is the sum of the apparent porosity and the closed porosity. The apparent porosity is also called the open porosity, which is the percentage of the pores in the sample that are connected to the atmosphere to the total volume of the sample. The closed porosity refers to the percentage of the total volume of the pores enclosed in the sample that are not connected to the outside world to the total volume of the sample.

[0062] The test results of the volume density, porosity and pore distribution of the bio-fermentation ultra-light foam ceramic new material of each group of embodiments and comparative examples are shown in Table 1.

[0063] Table 1 Test results of bulk density, porosity and pore distribution

[0064]

[0065] It can be seen from the test results provided in Table 1 that the bio-fermentation ultra-light foam ceramic new material prepared by each group of embodiments of the present invention not only has consistent pore size and uniform distribution, but also has a volume density D 体The porosity P and porosity P of the present invention are higher than those of the control groups, which indicates that the pore-forming agent of the present invention successfully solves the problems of different pore sizes, uneven distribution and low porosity of the porous ceramic materials produced by the existing fermentation technology through the synergistic effect of biological fermentation, chemical foaming decomposition and mechanical whipping, so that the volume density of the obtained biological fermentation ultra-light foam ceramic new material is lower than 0.3g / cm 3 , porosity is higher than 90%, and has microscopic characteristics of good uniformity and stability.

[0066] In Comparative Example 1, sugar is used as a foaming agent, and water vapor is generated by the condensation reaction between sugar molecules and OH to achieve the effect of pore formation. However, according to the test results of Comparative Example 1, the volume density of the ultra-light alumina foam ceramic obtained in Comparative Example 1 is 0.44 g / cm 3 , the porosity is only 89%, which is still relatively low.

[0067] The pore-forming agent of Comparative Example 2 is composed only of flour, water and yeast powder, and it is foamed and pore-formed only by a biological fermentation method, resulting in the obtained ceramic new material not only having a low porosity of only 80%, but also the foam ceramic slurry body obtained by mixing and stirring during the preparation process is relatively soft and not easy to shape, and cannot effectively prevent the sinking of the ceramic powder, resulting in the final pores being mostly distributed in the upper middle part of the ceramic body and the larger the pores are, the larger the pores are (this is because after the ceramic powder sinks, the flour content in the upper middle part of the ceramic body is relatively large, and after the flour is sintered, pores are left in the upper middle part of the ceramic body), especially the largest pore size at the top exceeds 2 mm, and the volume density is as high as 0.80 g / cm 3 .

[0068] In the pore-forming agent of Comparative Example 3, egg white liquid and vegetable oil are not added, which makes it impossible to effectively wrap the gas in the air into the ceramic slurry when the raw materials are stirred. At the same time, no protective film is formed on the surface of the foam produced by the fermentation product and the chemical foaming method. In addition, the lack of curing effect not only makes the foam retained in the ceramic slurry less, but also makes the foam more brittle and easy to break or be squeezed out, and the obtained bubbles are not fine, which ultimately leads to the volume density of the obtained bio-fermentation ultra-light foam ceramic new material being 0.63g / cm 3 , the porosity is only 84%; secondly, the pores in the ceramic body are unevenly distributed, with more pores in the middle and upper parts, and the largest pore at the top is also more than 2mm.

[0069] In Comparative Example 4, citric acid and ammonium bicarbonate were not added to the pore-forming agent, which not only reduced the foam in the ceramic slurry, but also greatly reduced the supporting force of the ceramic powder with a sinking tendency during stirring, fermentation and initial heating, resulting in a volume density of 0.42 g / cm 3, while the porosity is only 89%, and the pore distribution of the ceramic body is uneven, with more pores in the middle and upper parts.

[0070] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A new bio-fermented ultra-light foam ceramic material, It is characterized in that The invention comprises the following raw materials: a pore-forming agent, a toughening agent and ceramic powder; wherein the pore-forming agent comprises flour, water, yeast powder, egg white liquid, vegetable oil, citric acid and ammonium bicarbonate; and the raw materials specifically comprise, by weight, 100 parts of flour, 30 to 60 parts of water, 0.5 to 2 parts of yeast powder, 30 to 60 parts of egg white liquid, 5 to 10 parts of vegetable oil, 1 to 3 parts of citric acid, 3 to 6 parts of ammonium bicarbonate, 10 to 20 parts of toughening agent and 75 to 150 parts of ceramic powder.

2. The new bio-fermented ultra-light foam ceramic material as claimed in claim 1, It is characterized in that The ceramic powder is alumina powder, zirconium oxide powder, quartz powder or hydroxyapatite.

3. The new bio-fermented ultra-light foam ceramic material as claimed in claim 1, It is characterized in that The toughening aid is short-cut fiber cotton; the short-cut fiber cotton is synthetic fiber or natural fiber.

4. The new bio-fermented ultra-light foam ceramic material as claimed in claim 3, It is characterized in that The chopped fiber cotton is alumina fiber, zirconium oxide fiber, quartz fiber, polypropylene fiber, bamboo fiber or cotton.

5. The method for preparing the new bio-fermentation ultra-light foam ceramic material according to any one of claims 1 to 4, It is characterized in that The raw materials are stirred and mixed evenly, and then injected into a mold for fermentation at a temperature of 25 to 30° C. and a fermentation time of 30 to 60 minutes; the temperature is raised to 60 to 80° C. and kept warm for 12 to 24 hours to obtain a foam ceramic original dry blank; the foam ceramic original dry blank is sintered at 1100 to 1700° C. to obtain a new bio-fermented ultra-light foam ceramic material.

6. The method for preparing the new bio-fermentation ultra-light foam ceramic material as claimed in claim 5, It is characterized in that The stirring speed is 100-300 rpm.

7. The method for preparing the new bio-fermentation ultra-light foam ceramic material as claimed in claim 5, It is characterized in that The heating rate is 0.05-0.1°C / min.

8. The method for preparing the new bio-fermentation ultra-light foam ceramic material as claimed in claim 5, It is characterized in that The original dry foam ceramic blank is placed in a high-temperature electric furnace, heated to 1100-1700°C at a heating rate of 1-2°C / min and kept warm for 2-6 hours to obtain a new bio-fermented ultra-light foam ceramic material.

9. The method for preparing the new bio-fermentation ultra-light foam ceramic material as claimed in claim 5, It is characterized in that When alumina powder is used as the ceramic powder, the foam ceramic raw blank is sintered at 1600-1700°C; when zirconium oxide powder is used as the ceramic powder, the foam ceramic raw blank is sintered at 1500-1600°C; when quartz powder is used as the ceramic powder, the foam ceramic raw blank is sintered at 1550-1650°C; when hydroxyapatite is used as the ceramic powder, the foam ceramic raw blank is sintered at 1100-1200°C.

10. Use of the new bio-fermentation ultra-light foam ceramic material as claimed in any one of claims 1 to 4 in the preparation of furnace materials, medical bone filling materials, catalyst carriers or filter materials.

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