Acid-activated foamed materials and methods of making and articles

Abstract

This application relates to the field of lightweight building materials technology, and particularly to acid-activated foamed materials, their preparation methods, and components. The method for preparing acid-activated foamed materials includes: chemically reacting raw materials comprising active aluminosilicates, an acid activator solution, and a gas-generating component to obtain the acid-activated foamed material; wherein the acid activator solution contains phosphoric acid and / or acidic phosphates; the gas-generating component includes materials capable of reacting with the acid activator solution and releasing gas. This chemical reaction system includes an acid activation reaction and a gas-generating reaction. The acid activation reaction generates a phosphate-based polymer material through a dissolution-condensation reaction, exhibiting a certain strength. The gas-generating reaction and the acid activation reaction are coupled in terms of reaction sites and time, and the gas-generating process is also coupled with the process of increasing the viscosity of the reaction system. Therefore, the acid-activated foamed material has a uniform and stable pore structure and possesses advantages such as low density, thermal insulation, sound insulation, low energy consumption, fire resistance, and environmental friendliness.

Description

Technical Field

[0001] This application relates to the field of lightweight building materials technology, and in particular to acid-activated foamed materials and their preparation methods and components. Background Technology

[0002] Lightweight building materials are lighter than traditional building materials, giving them a significant advantage in transportation and construction. The most common type is foamed concrete, which is rich in closed micropores. Although its strength is relatively lower, it generally has advantages such as low density, heat insulation, sound insulation, low energy consumption, fire resistance, and environmental friendliness. It is widely used in building envelopes, thermal insulation, and functional components.

[0003] Existing technologies primarily achieve lightweighting through physical and / or chemical methods. Physical methods include mechanical agitation for air induction, physical foaming, or the incorporation of pre-fabricated foam. However, these methods suffer from drawbacks such as the independent operation of the foaming and hydration processes, susceptibility to foam collapse or merging, and uneven pore structure distribution. They often require the addition of surfactants to stabilize the foam, while the addition of organic materials can lead to environmental issues and the introduction of impurities. Chemical methods not only require the addition of chemical foaming agents, often organic ones, but also involve simultaneous gelation of the main material and foaming rate, uniformity, and stability. This makes it difficult to control these factors, leading to issues such as bubble merging, escape, or uneven expansion. The final product may exhibit a wide pore size distribution and a high proportion of irregular pores. These shortcomings of both physical and chemical methods result in insufficient density, thermal insulation, sound insulation, and environmental performance in the final lightweight building materials. Furthermore, existing methods are still primarily based on cement systems, resulting in inherent drawbacks such as high energy consumption and significant carbon emissions. Summary of the Invention

[0004] The purpose of this application is to provide acid-activated foaming materials and their preparation methods and components, aiming to solve the problem of poor performance in the preparation of lightweight building materials in the prior art.

[0005] To achieve the above-mentioned objectives, the technical solution adopted in this application is as follows: In a first aspect, this application provides a method for preparing an acid-activated foaming material, comprising: Acid-activated foaming material is obtained by chemically reacting raw materials including active aluminosilicate, acid activator solution, and gas-generating components. The acid activator solution contains phosphoric acid and / or acid phosphate; The gas-producing components include materials that can react with the acid activator solution and release gas.

[0006] The chemical reactions in the preparation method of this application include an acid-activated reaction (dissolution-condensation reaction) and a gas-generating reaction. On the one hand, the acid-activated reaction induces the active aluminosilicate to undergo a dissolution-condensation reaction through an acid activator solution, causing the silicon-oxygen bonds and aluminum-oxygen bonds in the active aluminosilicate to break, releasing silicon and aluminum elements. The active aluminosilicate dissolves (depolymerizes), and the entire raw material forms a sol. The depolymerized components will recombine with phosphate ions in phosphoric acid and / or acid phosphate to reconstruct -Si-O-Al-OP-, -Si-OPO-Al-O-, etc., and continuously condense and polymerize, reorganizing and condensing into a new three-dimensional polymeric network gel structure, namely a phosphate-based polymer network, forming a silica-aluminophosphate gel. This gel can gradually harden without high-temperature calcination, has a certain strength, and can be used as a building material. On the other hand, the acid activator solution also reacts with the gas-generating components to generate gas, and releases gas in situ during the acid-activated reaction. During the acid-activated process, it continuously creates pores in the generated sol and gel, and the final acid-activated foamed material has a rich pore structure. Unlike existing technologies that involve foaming followed by curing, and unlike methods that use external foam or foaming agents, this preparation method couples the acid-activated reaction and the gas-generating reaction at both the reaction site and time. Not only do both reactions use an acid activator solution as the reactant, but they also proceed simultaneously, generating gas in situ within the sol and gel. Furthermore, as the reaction progresses, the system viscosity and yield stress gradually increase, and the generated gas is encapsulated and fixed by the forming gel structure before it escapes, thus creating a uniformly distributed and stable pore structure within the material. Moreover, by controlling the raw materials and reaction conditions, the gas generation rate, bubble size and stability, and pore structure distribution can be effectively regulated, resulting in acid-activated foamed materials with advantages such as low density (lightweight), thermal insulation, sound insulation, low energy consumption, fire resistance, and environmental friendliness.

[0007] Secondly, this application provides an acid-activated foaming material, which is prepared by the method described above for preparing acid-activated foaming materials according to this application.

[0008] Since the above preparation method includes an acid-activated reaction, the resulting acid-activated foamed material is a phosphate-based polymer with a certain strength. This preparation method involves the synergistic action of the acid-activated reaction and the gas-generating reaction, which are coupled at the reaction sites and in terms of time. The gas-generating process is also coupled with the increase in viscosity of the reaction system. Therefore, the acid-activated foamed material has a uniform and stable pore structure, high porosity, and basic compressive strength. Furthermore, it possesses advantages such as low density, thermal insulation, sound insulation, low energy consumption, fire resistance, and environmental friendliness, making it suitable as a building material.

[0009] Thirdly, this application provides a component prepared from the aforementioned acid-activated foaming material of this application through a curing treatment.

[0010] The component of this application has a high porosity and basic compressive strength, and also has advantages such as low density, heat insulation, sound insulation, low energy consumption, fire resistance, and environmental protection. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 This is a schematic diagram of the preparation process of Example 22 of this application; Figure 2 This is a schematic diagram of the slurry after mixing in step S2 of Embodiment 1 of this application just being injected into the mold; Figure 3 This is a schematic diagram of the part prepared by using aluminum powder as a gas-generating component in Embodiment 16 of this application. Detailed Implementation

[0013] To make the technical problems, technical solutions, and beneficial effects of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0014] In this application, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0015] In this application, "at least one" means one or more, and "multiple" means two or more. "At least one of the following" or similar expressions mean any combination of these items, including any combination of single or multiple items.

[0016] It should be understood that in the various embodiments of this application, the order of the above processes does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0017] The weights of the relevant components mentioned in the embodiments of this application can refer not only to the specific content of each component, but also to the proportional relationship between the weights of the components. Therefore, any scaling up or down of the content of the relevant components according to the embodiments of this application is within the scope disclosed in the embodiments of this application. Specifically, the mass in the embodiments of this application can be a well-known unit of mass in the chemical industry, such as µg, mg, g, or kg.

[0018] The first aspect of this application provides a method for preparing an acid-activated foaming material, comprising: Acid-activated foaming material is obtained by chemically reacting raw materials including active aluminosilicate, acid activator solution, and gas-generating components. The acid activator solution contains phosphoric acid and / or acid phosphate (i.e., the acid activator includes phosphoric acid and / or acid phosphate, and is prepared as an acid activator solution). The gas-producing components include materials that can react with the acid activator solution and release gas.

[0019] The term "active" in this application refers to the fact that the active aluminosilicate is not a high-purity crystal; otherwise, it would not have the activity to react with acid activators. For ease of representation of its chemical composition, active aluminosilicates are often listed as oxides, containing SiO2, Al2O3, and may further contain other oxides.

[0020] The chemical reactions in the preparation method of this application include an acid-activated reaction (dissolution-condensation reaction) and a gas-generating reaction. On the one hand, the acid-activated reaction induces the active aluminosilicate to undergo a dissolution-condensation reaction through an acid activator solution, causing the silicon-oxygen bonds and aluminum-oxygen bonds in the active aluminosilicate to break, releasing silicon and aluminum elements. The active aluminosilicate dissolves (depolymerizes), and the entire raw material forms a sol. The depolymerized components will recombine with phosphate ions in phosphoric acid and / or acid phosphate to form -Si-O-Al-OP-, -Si-OPO-Al-O-, and other bonded structures, and continuously condense and polymerize, reorganizing and condensing into a new three-dimensional polymeric network gel structure, namely a phosphate-based polymer network, forming a silica-aluminophosphate gel. This gel can gradually harden without high-temperature calcination, has a certain strength, and can be used as a building material. On the other hand, the acid activator solution also reacts with the gas-generating components to generate gas, and releases gas in situ during the acid-activated reaction. During the acid-activated process, it continuously creates pores in the generated sol and gel, and the final acid-activated foamed material has a rich pore structure. Unlike existing technologies that involve foaming followed by curing, and unlike methods that use external foam or foaming agents, this preparation method couples the acid-activated reaction and the gas-generating reaction at both the reaction site and time. Not only do both reactions use an acid activator solution as the reactant, but they also proceed simultaneously, generating gas in situ within the sol and gel. Furthermore, as the reaction progresses, the system viscosity and yield stress gradually increase, and the generated gas is encapsulated and fixed by the forming gel structure before it escapes, thus creating a uniformly distributed and stable pore structure within the material. Moreover, by controlling the raw materials and reaction conditions, the gas generation rate, bubble size and stability, and pore structure distribution can be effectively regulated, resulting in acid-activated foamed materials with advantages such as low density (lightweight), thermal insulation, sound insulation, low energy consumption, fire resistance, and environmental friendliness.

[0021] In some embodiments, the active aluminosilicate has an amorphous and / or semi-crystalline structure. Amorphous active aluminosilicates exhibit higher reactivity; their Al-O and Si-O bonds are more easily broken compared to those in crystalline structures, facilitating rapid dissolution by acid activator solutions and initiation of subsequent polycondensation reactions. The X-ray diffraction patterns of this amorphous material are often diffuse. Semi-crystalline structures often possess both ordered crystalline and disordered amorphous regions, thus also exhibiting reactivity and can be activated by acid activator solutions to generate acid-activated foamed materials.

[0022] In some embodiments, the raw materials for active aluminosilicates include at least one of metakaolin, fly ash (such as low-calcium fly ash), iron slag (this type of metal slag is generally low-calcium), and calcined coal gangue powder. These raw materials are rich in active aluminosilicates, which facilitates acid activation reaction with acid activator solution to generate acid-activated foaming materials, thereby improving the strength and other properties of the obtained acid-activated foaming materials.

[0023] In some embodiments, the molar ratio of silicon to aluminum in the activated aluminosilicate is (1~2.5):1, which may include, but is not limited to, 1:1, 1.5:1, 2:1, 2.5:1, or any two of the above values ​​within a range. These molar ratios result in a higher proportion of active aluminum phase in the activated aluminosilicate. On the one hand, this is beneficial for increasing the dissolution rate in the initial stage of the acid-activated reaction, accelerating the dissolution-condensation process, and thus helping the gas to be promptly encapsulated and fixed during gel formation, improving the pore-forming effect. On the other hand, compared to silicon-oxygen structures, aluminum-oxygen structures are more likely to undergo coordination reactions with phosphate groups in the acid activator and further generate structural units such as Al-OP or Si-O-Al-OP, thereby promoting the construction of a three-dimensional polymer network gel structure and improving the structural stability and mechanical properties of the acid-activated foam material. This molar ratio can be measured by X-ray fluorescence spectroscopy (XRF).

[0024] In some embodiments, the molar percentage of calcium in the active aluminosilicate is less than or equal to 25%, and may include, but is not limited to, 3%, 5%, 10%, 15%, 25%, or values ​​within a range of any two of the above. After being dissolved in the acid activator solution, calcium readily reacts with phosphate ions to form calcium phosphate, calcium hydrogen phosphate, etc., which not only consumes phosphate ions but also hinders the formation of aluminum-silicon-oxygen-phosphorus chain segments, further affecting gel formation. However, a small amount of calcium ions has a relatively small impact on the overall reaction pathway, and can also form local precipitation or filling structures, providing some auxiliary benefits to the stability and density of the foam wall. Therefore, this mass percentage of calcium is beneficial to the dissolution-condensation process of the acid-activated reaction, and helps to improve the strength of the acid-activated foamed material.

[0025] In some embodiments, the particle size of the activated aluminosilicate is such that it passes through a 200-mesh sieve. This particle size facilitates sufficient contact between the acid activator solution and the activated aluminosilicate particles, and allows it to dissolve into the particle interior, thereby improving the efficiency and uniformity of the dissolution-condensation reaction.

[0026] Phosphoric acid and / or acid phosphates in the acid activator solution can provide hydrogen ions, which not only dissolve active aluminosilicates but also generate gas with the gas-producing components. The bubble generation process is coupled with the increase in viscosity of the reaction system, thus forming a uniformly distributed and stable pore structure in the acid-activated foaming material. Phosphoric acid and / or acid phosphates also provide sufficient phosphate ions, which can recombine with the components after depolymerization of active aluminosilicates to reconstruct silicoaluminophosphorus segments and condense into a three-dimensional network gel structure. In the example, the acid activator solution can be a phosphoric acid solution, an acid phosphate solution, or a mixed solution of phosphoric acid and acid phosphates.

[0027] In some embodiments, the acidic phosphates include at least one of aluminum dihydrogen phosphate and potassium dihydrogen phosphate, with aluminum dihydrogen phosphate being the preferred choice. These acidic phosphates are acidic and rich in phosphate ions, and therefore can act as acid activators to activate active aluminosilicates, causing a dissolution-condensation reaction. These acidic phosphates can also react with gas-generating components to produce gas, and the reaction yields the desired acid-activated foaming material.

[0028] In some embodiments, the acid activator solution contains at least one of sulfuric acid, hydrochloric acid, and organic acid. These acids can also provide hydrogen ions to assist phosphoric acid and / or acid phosphates in promoting the acid activation reaction, and can also generate gas with the gas-producing components. Furthermore, the sulfate and chloride ions in sulfuric acid and hydrochloric acid have large radii, making it difficult for them to bind to the silica-alumina-oxygen network. Consequently, they generate aluminum sulfate, aluminum chloride, and other components that fill the pores of the silica-alumina-oxygen-phosphorus three-dimensional network gel structure. Organic acids can generate organic carboxylic acid aluminum salts and other components, which then form an organic-inorganic hybrid network together with the main silica-alumina-oxygen-phosphorus three-dimensional polymeric network gel structure. In exemplary embodiments, the acid activator in the acid activator solution may consist only of the aforementioned phosphoric acid and / or acid phosphates. In the example, the acid activator in the acid activator solution may include a primary activator and a secondary activator. The primary activator includes the above-mentioned phosphoric acid and / or acid phosphate, and the secondary activator includes at least one of the above-mentioned sulfuric acid, hydrochloric acid, and organic acid. In the acid activator, the mass percentage of the primary activator is greater than or equal to 50% and less than 100%, and the mass percentage of the secondary activator is greater than 0% and less than or equal to 50%.

[0029] In some embodiments, at 25°C, the pH value of the acid activator solution is 1 to 3, which may include, but is not limited to, 1, 1.5, 2, 2.5, 3, or any two of the above values. These pH values ​​of the acid activator solution are beneficial for maximizing the dissolution reaction kinetics of the acid activator solution; simultaneously, these pH values ​​also facilitate the rapid generation of gas from the gas-producing components, promoting the temporal coupling of the acid activation reaction and the gas-producing reaction, and further coupling with the process of increasing the viscosity of the reaction system. This allows for the regulation of bubble size, improved bubble stability, and control of the pore structure of the acid-activated foaming material, ensuring its uniform distribution and stability, thereby improving density, thermal insulation, and other properties.

[0030] In some embodiments, the solvent of the acid activator solution includes water. Water, as a solvent, can be formulated with the acid activator to form an acid activator solution, which ionizes to produce hydrogen ions for acid activation reactions with active aluminosilicates and for gas-generating reactions with gas-producing components. Using water as a solvent also facilitates uniform dispersion of raw materials and allows the gas generated in the gas-generating reaction to form bubbles, improving pore-forming effects and thus enhancing properties such as density and heat insulation.

[0031] In some embodiments, the gas-generating components include at least one of the following: normal carbonate, acidic carbonate, basic carbonate, and metal; all of these gas-generating components can react with the acid activator solution to generate gas.

[0032] The carbonates can include at least one of sodium carbonate, potassium carbonate, calcium carbonate, magnesium carbonate, zinc carbonate, and dolomite powder. Acidic carbonates can include at least one of sodium bicarbonate, potassium bicarbonate, and ammonium bicarbonate. These carbonates can react with the acid activator solution to generate carbon dioxide gas, which then forms bubbles, synergistically contributing to pore formation through the acid-activated reaction. The bubble formation process is coupled with the increase in viscosity of the reaction system, which is beneficial for the uniform and stable distribution of the pore structure, thus generating acid-activated foamed materials. During the gas-generating reaction, some carbonates can also generate zinc and magnesium ions, forming phosphate precipitates or complexes, promoting bubble encapsulation and bubble wall solidification, which is beneficial for improving the foaming structural strength of acid-activated foamed materials; other carbonates generate sodium and potassium ions, mainly playing a role in neutralizing acid, adjusting pH, and regulating the reaction rate.

[0033] The metal can include at least one of aluminum, zinc, and iron. These metals react with the acid activator solution to generate hydrogen gas, which then forms bubbles. Simultaneously, aluminum, zinc, and iron ions are generated. These metal ions function similarly to zinc and magnesium ions in carbonates, promoting bubble encapsulation and bubble wall solidification, thus improving the strength of the foamed structure of the acid-activated foam material. Aluminum ions generated from aluminum metal also participate in the formation of aluminosilicate phosphate, further contributing to the construction of the three-dimensional network and improving the strength after gel curing. Regarding the safety of hydrogen, it is widely used in existing cement-based building materials, such as aerated concrete and foamed concrete. Relevant standards such as GB / T 2085.2 and JC / T407 can be referenced. Furthermore, the hydrogen production process can be effectively controlled through standard operating procedures, such as operating in a well-ventilated environment and avoiding open flames. Hydrogen will evaporate or be replaced by air over time and will not accumulate over a long period. The residual hydrogen content in the final acid-activated foam material is extremely low, therefore its safety is controllable.

[0034] In some embodiments, the particle size of the gas-generating component is such that it passes through a 200-mesh sieve. This particle size facilitates sufficient contact between the acid activator solution and the gas-generating component particles, allowing them to dissolve into the particle interior and improving the efficiency and uniformity of the gas-generating reaction. This particle size also facilitates uniform mixing of the gas-generating component with the active aluminosilicate, thereby promoting the coupling of the acid activation reaction and the gas-generating reaction at the reaction sites, enabling in-situ gas generation in the sol and gel, and improving the uniformity of bubble formation. This results in a uniform and stable pore structure distribution in the acid-activated foamed material, thereby improving properties such as density and thermal insulation.

[0035] In some embodiments, the mass ratio of active aluminosilicate to the gas-generating component is (97~99.9):(3~0.1); this can include, but is not limited to, ratios of 97:3, 98:2, 99:1, 99.9:0.1, or any two of the above ratios. This mass ratio affects the rate and final degree of the acid-activated reaction and the gas-generating reaction, respectively. This ratio facilitates kinetic matching between the acid-activated reaction and the gas-generating reaction, enabling temporal coupling between in-situ bubble generation and the dissolution-condensation reaction process. Furthermore, the bubble generation process is coupled with the increase in viscosity of the reaction system, further resulting in a uniform and stable pore structure distribution in the acid-activated foaming material, thereby improving density, thermal insulation, and other properties.

[0036] In some embodiments, the water-cement ratio in the raw materials of the chemical reaction is 0.3 to 0.5, and may include, but is not limited to, 0.3, 0.35, 0.4, 0.45, 0.5, or any two of the above values ​​within a range. This water-cement ratio is obtained by using water in the acid activator solution, active aluminosilicate and gas-generating components as powders, and water by mass ratio to powder. This water-cement ratio facilitates uniform dispersion of the slurry formed by mixing the acid activator solution and powders, promotes the full progress of the acid activation reaction and gas generation reaction, and ensures high coupling at the reaction sites, achieving in-situ gas generation and pore formation. It also facilitates the matching of the amounts of the two powders and the acid activator solution, allowing the acid activation reaction and gas generation reaction to proceed fully. The process of bubble generation is further coupled with the process of increasing the viscosity of the reaction system, which is beneficial for a uniform and stable pore structure distribution, thereby improving density, heat insulation, and other properties.

[0037] In some embodiments, the chemical reaction includes pressure regulation of the reaction environment to a pressure of 2 atm to 5 atm for a duration of 2 h to 240 h, followed by depressurization to atmospheric pressure. The pressure can be regulated to values ​​including, but not limited to, 2 atm, 3 atm, 4 atm, 5 atm, or any two of these values. The duration can be 2 h, 24 h, 48 h, 120 h, or 240 h, depending on the initial setting time of the matrix. The depressurization time can be 2 h to 72 h, and the depressurization rate can be 0.02 atm / h to 1 atm / h. This method of applying and regulating external pressure helps to suppress gas expansion and aggregation in the early stages of the reaction, regulates the bubble formation rate and precipitation behavior, and allows it to couple with the acid-induced reaction and the increase in viscosity of the reaction system, thereby controlling the degree of foaming and optimizing the pore structure.

[0038] In some embodiments, the chemical reaction includes dry mixing of active aluminosilicate and gas-generating components to obtain a powder, followed by wet mixing of the powder with an acid activator solution for a duration of 5 minutes or less, and finally, a settling period of 2 to 240 hours. This method of first dry mixing the powder and then wet mixing it with the acid activator solution facilitates thorough and uniform mixing and dispersion of the raw material components, promotes the full progress of the acid activation and gas generation reactions, and achieves high coupling at the reaction sites. In-situ gas generation and pore formation occur, and the bubble generation process is coupled with the increase in viscosity of the reaction system, resulting in a more uniform and stable pore structure distribution, thereby improving density, insulation, and other properties. The duration of wet mixing prevents the gas-generating reaction from becoming excessive, thus avoiding premature escape of the generated bubbles under continuous stirring and shearing. It also reduces the disruption of already formed fine bubbles, resulting in a more uniform pore structure. These two factors ensure a sufficient number of fixed bubbles in the system, leading to adequate solidification. This is beneficial for producing acid-activated foamed materials with sufficient foam content, high porosity, and reduced apparent density, thereby improving lightweight insulation performance. Static setting facilitates the initial and final setting of phosphate-based polymer materials.

[0039] Furthermore, the aforementioned wet mixing process, where the acid-activating solution is added to the powder, offers the following advantages: the powder is initially in a uniformly dry-mixed state, resulting in a more even distribution of the gas-generating components; as the acid-activating solution gradually wets the powder, the gas-generating reaction occurs simultaneously from multiple micro-regions, making it easier to obtain a uniform pore structure. Conversely, if the powder is added to the acid-activating solution, localized powder will react rapidly upon contact with the solution, especially the surface of the gas-generating components, which will immediately release gases such as CO2 and hydrogen. This can easily lead to intense localized foaming, clumping, and encapsulation of unreacted powder, resulting in decreased slurry uniformity, wider pore size distribution, and an increased proportion of large pores, thus affecting the performance of the acid-activated foaming material.

[0040] In some embodiments, the raw material for the activated aluminosilicate includes metakaolin, with a silica-to-alumina molar ratio of (1~2.5):1; the gas-generating component includes at least one of a normal carbonate, an acid carbonate, a basic carbonate, and a metal, including aluminum or zinc; the particle size of the metakaolin and the gas-generating component is such that they pass through a 200-mesh sieve, and the mass ratio of metakaolin to the gas-generating component is (97~99.9):(3~0.1); the pH value of the acid activator solution at 25°C is 1~3; the water-to-ash ratio in the raw materials for the chemical reaction is 0.3~0.5; the chemical reaction includes pressure control of the reaction environment to maintain an ambient pressure of 2 atm~5 atm for 2 h~240 h, followed by depressurization to atmospheric pressure. This preparation method simultaneously carries out the acid activation reaction and the gas-generating reaction, which is beneficial for in-situ gas generation and couples the bubble formation process with the dissolution-condensation process. On the one hand, this method further selects the types and ratios of the three raw material components to make the gas generation rate and bubble formation rate controllable. On the other hand, the gel structure formed by metal ions will also encapsulate and solidify the bubbles. Furthermore, external gas pressure is introduced to regulate the gas generation and bubble expansion process. By setting these three parameters, the gas generation rate and precipitation behavior can be finely controlled, and excessive bubble growth and merging can be suppressed. This couples the bubble formation rate with the acid-activated reaction rate and the increase in the viscosity of the reaction system. After the acid-activated foaming material is obtained, the proportion of large pores can be reduced and the pore size distribution can be optimized to obtain a uniform and stable pore structure.

[0041] A second aspect of this application provides an acid-activated foaming material, which is prepared by the method described in the embodiments of this application for preparing acid-activated foaming materials.

[0042] Since the above preparation method includes an acid-activated reaction, the resulting acid-activated foamed material is a phosphate-based polymer with a certain strength. This preparation method involves the synergistic action of the acid-activated reaction and the gas-generating reaction, which are coupled at the reaction sites and in terms of time. The gas-generating process is also coupled with the increase in viscosity of the reaction system. Therefore, the acid-activated foamed material has a uniform and stable pore structure, high porosity, and basic compressive strength. Furthermore, it possesses advantages such as low density, thermal insulation, sound insulation, low energy consumption, fire resistance, and environmental friendliness, making it suitable as a building material.

[0043] A third aspect of this application provides a component obtained by curing the acid-activated foaming material described in the above-described embodiments of this application.

[0044] The components of the embodiments of this application have high porosity and basic compressive strength, and also have advantages such as low density, heat insulation, sound insulation, low energy consumption, fire resistance, and environmental protection.

[0045] In some embodiments, the curing temperature is 20°C to 30°C, the relative humidity is 40% to 95%, and the duration can be 2 hours to 240 hours. Since the acid-activated geopolymer does not rely on external water supply for curing but is dominated by the internal reaction system, it does not have strict requirements on the curing conditions of cement-like materials and can be cured under sealed, covered, or aforementioned humidity conditions. The curing process causes the remaining silica-alumina-phosphorus molecular chains to further crosslink gradually until they essentially condense into a phosphate-based macropolymer network, while moisture is locked in or evaporated, thereby hardening the silica-alumina-phosphate gel to obtain the molded part.

[0046] In some embodiments, the part satisfies at least one of the following: (1) Compressive strength is 1 MPa to 240 MPa; (2) Porosity is 30%~75%; (3) The apparent density is 400 kg / m³ 3 ~1200 kg / m 3 ; (4) The thermal conductivity is 0.05 W / (m·K)~0.25 W / (m·K).

[0047] The following description is based on specific embodiments, and the comparison of some parameters of each embodiment and comparative example is recorded in Tables 1 and 2 below.

[0048] Example 1 This embodiment provides an acid-activated foaming material and a molded part, including the following steps S1~S3: S1: Provide raw materials.

[0049] Phosphoric acid was used as the acid activator. A 70% (w / w) phosphoric acid solution was first prepared, and water was added to adjust the pH to 1.6 at 25°C to obtain the acid activator solution. Metakaolin powder was used as the inorganic precursor containing active aluminosilicates, and calcium carbonate powder was used as the gas-generating component, with a mass ratio of metakaolin:calcium carbonate of 99.5:0.5. Both powders could pass through a 200-mesh sieve, and the two powders together constituted the powder. The water-cement ratio was 0.4, meaning the mass ratio of water to powder in the acid activator solution was 0.4:1. The molar percentages of each element in the metakaolin were: 48.8% Si, 48.2% aluminum, 0.8% iron, 0.5% calcium, 0.5% potassium, 0.3% sodium, and trace amounts of other components. The molar ratio of silicon to aluminum was 1.01:1.

[0050] S2: Preparation of acid-activated foaming materials.

[0051] At room temperature, metakaolin powder and calcium carbonate powder are first dry-mixed to obtain a uniform powder. Then, a pre-prepared acid activator solution is slowly added to the powder along the inner wall of the mixing container, with simultaneous stirring. The acid activator solution is added in three portions, with each addition spaced 30 seconds apart, maintaining rapid stirring during this process to ensure thorough wetting of the powder and prevent excessively high local acid concentrations. After all the solution is added, rapid stirring continues until a uniform slurry is formed. The total stirring time is controlled at 3 minutes, and the stirring speed is 200 rpm. Figure 2 As shown, the material was poured into a 40 mm × 40 mm × 40 mm plastic mold, and the final solidified acid-activated foamed material was obtained after 7 days. The 7-day period was to ensure that the sample structure was stable and not easily damaged before demolding.

[0052] S4: Curing yields the finished part.

[0053] The acid-activated foaming material after demolding is cured at room temperature to obtain the part. The curing period is 28 days from the start of stirring to the final part formation. In this embodiment, the curing time is 28 days - 7 days = 21 days after demolding.

[0054] Examples 2 to 5 These embodiments provide acid-activated foaming materials and components, differing from Embodiment 1 only in the adjustment of metakaolin; all other aspects are the same. Specifically, Embodiment 2 uses Grade F fly ash with a silicon-to-aluminum molar ratio of 2.0:1 and a calcium molar content of approximately 3.4%. Embodiment 3 uses Grade C fly ash with a silicon-to-aluminum molar ratio of 1.8:1 and a calcium molar content of approximately 15%. Embodiment 4 uses iron slag with a silicon-to-aluminum molar ratio of 2.5:1 and a calcium molar content of approximately 3.6%. Embodiment 5 uses calcined coal gangue powder with a silicon-to-aluminum molar ratio of 1.5:1 and a calcium molar content of approximately 2.7%.

[0055] Examples 6 to 8 These embodiments provide acid-activated foaming materials and components, differing from Embodiment 1 only in that the type of acid activator is adjusted; all other aspects are the same. In Embodiment 6, aluminum dihydrogen phosphate is used instead. In Embodiment 7, the mass ratio of phosphoric acid to aluminum dihydrogen phosphate in the phosphoric acid solution is 1:1. In Embodiment 8, the mass ratio of phosphoric acid to citric acid (solid powder) in the phosphoric acid solution is 1:1; specifically, 1.0 part of a 70 wt.% phosphoric acid solution is added, followed by 0.7 parts of citric acid powder, and then water is added to adjust the pH.

[0056] Examples 9 to 11 These embodiments provide acid-activated foaming materials and components, differing from Embodiment 1 only in that the pH value of the acid activator solution is adjusted; all other aspects remain the same. Specifically, Embodiment 9 has a pH value of 1.0 at 25°C. Embodiment 10 has a pH value of 3.0 at 25°C. Embodiment 11 adjusts the type of acid activator, changing the mass ratio of phosphoric acid to citric acid in the phosphoric acid solution to 1:1, while simultaneously reducing the amount of both phosphoric acid and citric acid, thus changing the pH value of the acid activator solution to 3.0 at 25°C.

[0057] Examples 12-16 These embodiments provide acid-activated foaming materials and components, differing from Embodiment 1 only in that the types of gas-generating components are adjusted; all other aspects remain the same. Specifically, Embodiment 12 uses magnesium carbonate instead of magnesium carbonate. Embodiment 13 uses sodium bicarbonate instead of sodium bicarbonate. Embodiment 14 uses zinc powder, and the mass ratio of metakaolin to zinc powder is changed from 99.5:0.5 to 99.7:0.3. Embodiment 15 uses aluminum powder, and the mass ratio of metakaolin to aluminum powder is changed from 99.5:0.5 to 99.9:0.1. Embodiment 16 also uses aluminum powder, and the mass ratio of metakaolin to aluminum powder is changed from 99.5:0.5 to 99.95:0.05, resulting in components as shown. Figure 3 As shown. The mass ratio was adjusted in Examples 14 to 16 because these two metals are relatively light. If the same mass ratio was used as in Example 1, the gas production would be too high. In addition, these two metals are highly reactive, especially aluminum, which has a high reactivity and a too fast gas production rate. These two factors can easily cause bubble merging, bubble collapse, and an increase in interconnected pores, which would reduce mechanical properties and structural stability. Therefore, the amount of metal powder used was reduced.

[0058] Examples 17 to 20 These embodiments provide acid-activated foaming materials and components, differing from Embodiment 1 only in that the mass ratio of the three raw materials is adjusted; all other aspects remain the same. Specifically, Embodiments 17 and 18 modify the water-cement ratio. In Embodiment 17, it is changed to 0.3, and in Embodiment 18, it is changed to 0.5. Embodiments 19 and 20 modify the mass ratio of metakaolin and the gas-producing component; in Embodiment 19, it is changed to 97.0:3.0, and in Embodiment 20, it is changed to 99.9:0.1.

[0059] Examples 21 to 26 These embodiments provide acid-activated foaming materials and components, differing from Embodiment 1 only in the adjustment of process parameters; all other aspects are the same. In Embodiments 21-25, after stirring in step S2, the material is rapidly poured into a mold and immediately placed into a sealed container. The pressure inside the sealed container is adjusted for initial curing, and after 48 hours, the pressure is slowly released (at 0.3 atm / h) to atmospheric pressure and the material is demolded, thus completing step S2. In Embodiment 21, the pressure inside the sealed reactor is changed to 2 atm. In Embodiment 22, the pressure inside the sealed reactor is changed to 3 atm. The preparation process is illustrated in the schematic diagram below. Figure 1 As shown. In Example 23, the gas pressure inside the sealed reactor was changed to 5 atm. In Example 24, the gas pressure inside the sealed reactor was changed to 8 atm. In Example 25, compared to Example 22, the stirring time in step S2 was further increased to 10 min. In Example 26, the gas pressure inside the sealed reactor was changed to 3 atm, and the phosphoric acid solution was changed to aluminum dihydrogen phosphate solution, while the pH value remained unchanged.

[0060] Comparative Example 1 The only difference between this comparative example and Example 1 is that there is no gas-producing component; everything else is the same.

[0061] Comparative Example 2 The only difference between the comparative example and Example 1 is that the acid activator was adjusted, with hydrochloric acid, sulfuric acid, and citric acid being tried sequentially. Everything else remained the same. However, these non-phosphoric acids failed to harden metakaolin. When hydrochloric acid, sulfuric acid, or citric acid were used alone as acid activators, although they could provide hydrogen ions and promote the breaking of some Si-O and Al-O bonds in metakaolin, causing a certain degree of acid dissolution, these acids could not provide the phosphorus source needed to construct the phosphate-based polymer network, making it difficult to form characteristic structural units such as Al-OP and Si-O-Al-OP. Therefore, it was difficult to establish a continuous and stable silica-aluminophosphate gel network in the system, resulting in insufficient slurry hardening ability and the inability to form stable components with effective self-supporting strength.

[0062] Comparative Example 3 This comparative example employs a pre-foaming, then curing process and also belongs to an acid-activated system. Specifically, it uses a pre-foaming process, omitting the gas-generating component from Example 1, and instead adding pre-made bubbles during the mixing of the acid activator solution and the precursor. The specific procedure is as follows: The acid activator solution and metakaolin from Example 1 were used, but calcium carbonate powder was not added, and the water-cement ratio remained at 0.4.

[0063] Sodium dodecylbenzenesulfonate (SDBS) is provided. It is a commonly used pre-foaming agent for the physical foaming method of foamed concrete. It is mixed with water at a mass ratio of 2.0:98.0 and added to a foaming machine. The mixture is stirred at 2000 rpm for 3 minutes to prepare pre-foam.

[0064] Weigh out the corresponding mass of pre-made foam according to the mass ratio of (acid activating solution + precursor): pre-made foam of 97.0:3.0. Then proceed with step S2 of Example 1, except that when the total stirring time reaches 3 minutes, add the weighed pre-made foam and continue stirring at 100 rpm for another 3 minutes. The subsequent casting and demolding processes remain unchanged.

[0065] Comparative Example 4 This comparative example uses a cement system. The specific procedure is as follows: Ordinary Portland cement and aluminum powder are mixed at a mass ratio of 99.9:0.1. After thorough mixing, a cement paste is prepared with a water-cement ratio of 0.4, i.e., a water to (cement + aluminum powder) mass ratio of 0.4:1. Water is added to the cement powder in three additions, with each addition spaced 30 seconds apart, while maintaining a stirring speed of 200 rpm. After all water is added, the stirring speed is maintained at 200 rpm until a homogeneous paste is formed. The total stirring time is controlled to be 3 minutes. The paste is then poured into 40 mm × 40 mm × 40 mm plastic molds. Due to the rapid hardening of cement, it reaches final setting in 24 hours. Therefore, it is demolded after 24 hours, and cured at a temperature of 20℃ ± 2℃ and a relative humidity of not less than 95% until the specified curing age. The resulting cement-based foamed material has been formed into the molded component.

[0066] The comparison of some parameters of each embodiment and comparative example is shown in Table 1 and Table 2.

[0067]

[0068]

[0069] Related performance tests 1. Relevant tests on part performance 1.1 Compressive strength The specimens from each case were tested using the pressure loading method, specifically using a domestically produced YAW-300B microcomputer-controlled compressive strength testing machine, referring to GB / T 17671 "Test Method for Strength of Cement Mortar". Before testing, the specimens were cured to the specified age of 28 days, placed in the center of the pressure plate, and loaded at a constant loading rate of 0.5 kN / s until failure. The maximum failure load was recorded, and the compressive strength was calculated.

[0070] 1.2 Apparent density The components from each case were tested using the mass-volume method, specifically with an electronic balance and vernier calipers, referring to GB / T 5486 "Test Methods for Inorganic Rigid Thermal Insulation Products". After drying the specimens to constant weight, their mass was measured, and their length, width, and height were also measured. The volume of the specimens was calculated, and the apparent density was obtained by dividing the mass by the volume.

[0071] 1.3 Porosity Before testing, the part was vacuum-saturated with water for 24 hours. Porosity was measured using a domestically produced Meso-MR12–060H-l low-field nuclear magnetic resonance spectrometer. The saturated water signal intensity was compared with the calibration curve to calculate porosity, and the pore size distribution was analyzed using T2 relaxation spectroscopy. Test parameters were set as follows: waiting time 1500 ms, 2000 echoes, and a cumulative count of 16.

[0072] 1.4 Thermal conductivity The components from each case were tested using a heat flow meter, specifically a NETZSCH HFM 436 / 3 / 1E thermal conductivity meter, following GB / T 10295 "Determination of Steady-State Thermal Resistance and Related Properties of Insulation Materials - Heat Flow Meter Method". Before testing, the samples were dried to constant weight, ensuring their upper and lower surfaces were flat and of uniform thickness. The samples were then placed between the upper and lower heating plates of the instrument. Under the set average temperature and temperature difference between the upper and lower plates, the thermal conductivity of the samples was measured and calculated after the heat flow signal stabilized.

[0073] Results Analysis In Example 1, during the mixing and molding process, the acidic activating component induced a dissolution and structural reconstruction reaction in metakaolin, while calcium carbonate reacted with the acid to generate carbon dioxide gas in situ. As the dissolution-condensation reaction continued, the viscosity of the system gradually increased, and the generated gas was effectively retained inside the slurry, forming a uniform porous structure. The 28-day compressive strength was 8.2 MPa, the porosity was 46%, and the apparent density of the block was 938.4 kg / m³. 3 It has a thermal conductivity of 0.15 W / (m·K), and all its properties are quite ideal. It is strong enough, lightweight, soundproof, and heat-insulating.

[0074] Examples 2 to 5 show that by adjusting the composition of the precursor materials, they all exhibit high compressive strength, low density, high porosity, and low thermal conductivity.

[0075] In Example 2, the F-grade fly ash has a relatively higher Si content and a highly polymerized precursor structure. Under acid-activated conditions, the fracture rate is slower, resulting in a slower release rate of active Si and Al species. This slows down the formation and condensation process of the Si-O-Al-OP network, and the performance is slightly lower than that of Example 1.

[0076] Compared with F grade fly ash, the C grade fly ash in Example 3 has a higher calcium content. The higher calcium content makes it easier to form calcium phosphate precipitate with phosphoric acid, which has an adverse effect on the mechanical properties of the matrix. Therefore, its compressive strength is slightly lower than that of Example 2, but its other properties are slightly better.

[0077] The iron slag in Example 4 contains a relatively high amount of iron, which will form an amorphous phase within the matrix during the reaction. The calcined coal gangue powder in Example 5 contains inert substances such as quartz and hematite, resulting in lower reactivity. Its performance is comparable to that of the previous examples, with varying degrees of advantages and disadvantages.

[0078] Examples 6 to 8, by adjusting the type of acid activator, all exhibited high compressive strength, low density, high porosity, and low thermal conductivity.

[0079] In Example 6, phosphoric acid was replaced with aluminum dihydrogen phosphate. Compared to phosphoric acid, aluminum dihydrogen phosphate not only provides an acidic environment and phosphate ions, but also introduces an additional aluminum source. This aluminum source can participate in the formation of Al-OP bonds and promote the further condensation of silica-alumina species dissolved from metakaolinite into a Si-O-Al-OP three-dimensional network, thereby improving the continuity and mechanical properties of the matrix. When aluminum dihydrogen phosphate is used alone, it directly introduces aluminum ions, which readily and rapidly form Al-OP-like gels with phosphate ions. This results in a faster increase in viscosity in the early stages of the system and limits the further generation and expansion of bubbles. Therefore, compared to Example 1, it exhibits reduced foaming degree, decreased porosity, and increased apparent density and thermal conductivity. Its advantage is improved compressive strength.

[0080] In Example 7, phosphoric acid was replaced with a combination of phosphoric acid and aluminum dihydrogen phosphate. The former is beneficial to the dissolution of active Si and Al components in metakaolin, while the latter is beneficial to supplement aluminum phosphorus structural units. The two exhibit a synergistic effect, thus significantly improving the compressive strength.

[0081] In Example 8, phosphoric acid was replaced with a mixture of phosphoric acid and citric acid, resulting in a slightly improved foaming degree compared to Example 1.

[0082] Examples 9 to 11, which adjusted the pH value of the acid activator solution, all exhibited high compressive strength, low density, high porosity, and low thermal conductivity.

[0083] In Example 9, the acidity was too strong, which led to more intense dissolution of Si and Al in the metakaolin, but the condensation hardening was inhibited. At the same time, the CaCO3 gas production reaction was faster, which easily caused large bubbles and more interconnected pores, thus reducing strength, increasing porosity and decreasing density.

[0084] In Example 10, insufficient acidity led to incomplete dissolution of metakaolin and incomplete formation of the Al-OP / Si-O-Al-OP network. Although the CaCO3 reaction was slowed down and the pore structure may have become slightly more stable, the matrix bonding strength was insufficient, resulting in a decrease in overall strength. Simultaneously, an increase in pH reduced the reaction rate between CaCO3 and the acid activator, slowing down the CO2 release process. This helped suppress early, vigorous foaming and rapid bubble coalescence, thus improving pore structure stability to some extent.

[0085] In Example 11, during the mixing and molding process, the acidic activating component promotes the dissolution and structural reconstruction of metakaolin, while calcium carbonate reacts with the acid to generate carbon dioxide gas in situ. The composite acid system can regulate the gas generation rate, effectively retaining the generated gas within the system during the slurry thickening process, thus forming a more uniform pore structure. After casting and molding, the slurry was cured at room temperature, achieving a compressive strength of 6.9 MPa after 28 days, a porosity of 51%, an apparent density of 872.3 kg / m³, and a thermal conductivity of 0.12 W / (m·K). This example utilizes a phosphoric acid and citric acid composite acid system, raising the pH to approximately 3.0 to reduce the carbonate reaction rate and thus regulate the gas generation rate. Compared to Example 1, the composite acid system effectively slows down the gas generation process, better matching the gas release with the slurry viscosity increase, thereby forming a more uniform and stable pore structure. The resulting material had a porosity of 51% and an apparent density of 872.3 kg / m³, while maintaining a compressive strength of 6.9 MPa, indicating that the foaming process can be effectively controlled by adjusting the composition of the acid system. The situation is similar to that of Example 10, with the only difference from Example 8 being the pH value; the overall performance is also quite similar, demonstrating that phosphoric acid can be combined with other acids.

[0086] Examples 12 to 16, which adjust the types of gas-producing components, all exhibit high compressive strength, low density, high porosity, and low thermal conductivity.

[0087] In Example 12, magnesium carbonate was used instead of phosphate. It can react with acid to release carbon dioxide, but its reinforcing effect on the silica-aluminophosphate network is relatively weak. At the same time, it may form local magnesium phosphate species with phosphate, competing for some phosphate and causing a slight decrease in the mechanical properties of the matrix.

[0088] Example 13 uses sodium bicarbonate, which reacts with acid faster and can significantly reduce the apparent density and thermal conductivity of the material. However, rapid gas production can lead to bubble merging and an increase in interconnected pores. At the same time, sodium ions may cause soluble salt residue and a decrease in water resistance. Therefore, its compressive strength is lower than that of the example using calcium carbonate and magnesium carbonate.

[0089] Example 14 uses zinc powder instead, and the amount used is reduced. The zinc ions generated by the reaction of zinc powder usually do not participate in the construction of the geopolymer network, and are more likely to form local zinc phosphate precipitates with phosphate ions, consuming some phosphate ions, thus having a slight impact on the mechanical properties of the geopolymer.

[0090] Example 15 used aluminum powder instead, with a further reduction in dosage. Compared to zinc powder, the aluminum ions generated by the reaction of aluminum powder with acid can serve as an aluminum source to participate in the construction of the silica-alumina phosphate network. During mixing and molding, the acidic activating component promotes the dissolution and structural reconstruction of metakaolin, while the aluminum powder reacts with acid to generate hydrogen gas in situ. After the slurry was cast and cured at room temperature, the compressive strength after 28 days was 4.2 MPa, the porosity was 58%, and the apparent density of the block was 721.7 kg / m³. 3 The thermal conductivity is 0.10 W / (m·K). In this embodiment, aluminum powder is used as the gas-generating component, and the system foams by generating hydrogen gas through the reaction of aluminum with acid. Due to the high reactivity of aluminum powder, the gas generation rate of the system is fast, ultimately forming a porous structure with higher porosity, making the material porosity reach 58% and reducing the apparent density to 721.7 kg / m³. 3 The thermal conductivity was further reduced to 0.10 W / (m·K), but excessive porosity also affected the compressive strength. The results show that the system of this invention can achieve adjustable control of material density and thermal insulation performance by changing the type of gas-generating components to regulate the amount of gas generated and the degree of foaming.

[0091] Example 16 also uses aluminum powder, but the amount used is further reduced compared to Example 15, and the compressive strength is improved. It can be seen that when the types of gas-producing components are different, it is necessary to adjust the amount and other parameters accordingly to improve the performance of the case.

[0092] Examples 17 to 20 show that by adjusting the water-cement ratio and the mass ratio of the two powders, the results exhibit high compressive strength, low density, high porosity, and low thermal conductivity.

[0093] In Example 17, the water-cement ratio was changed to 0.3. When the water content is low, the slurry viscosity is high, the expansion and migration of air bubbles are restricted, the overall porosity is reduced, and the matrix is ​​denser, thus increasing the strength. However, an excessively low water-cement ratio may lead to insufficient slurry fluidity, uneven local encapsulation, or uneven pore size distribution.

[0094] In Example 18, the water-cement ratio was changed to 0.5, resulting in more moisture, a looser hardened skeleton, increased pore size, and a slight decrease in strength.

[0095] In Example 19, the mass ratio of metakaolin to calcium carbonate was 97.0:3.0. When the calcium carbonate content increased to 3.0 wt.%, the CO2 generation increased significantly, leading to increased porosity and decreased density and thermal conductivity; simultaneously, Ca... 2+Competition with phosphate for precipitation is enhanced, resulting in a significant decrease in compressive strength, but the parts are lighter, soundproof, and heat-insulating.

[0096] In Example 20, the amount of calcium carbonate was reduced, and the amount of bubbles was reduced, so the strength of the part was improved, but other properties were reduced.

[0097] Examples 21-25, by adjusting the process parameters, all exhibited high compressive strength, low density, high porosity, and low thermal conductivity. In Examples 21-23, increasing the ambient gas pressure during the reaction process to 2 atm-5 atm significantly improved the compressive strength and regulated bubble formation. This indicates that under higher ambient pressure, gas generation and aggregation are suppressed, thereby reducing the degree of foaming and regulating the pore structure.

[0098] Example 22 showed a 28-day compressive strength of 14.1 MPa, a porosity of 39%, and an apparent density of 1014.7 kg / m³. 3 The thermal conductivity is 0.17 W / (m·K). In this embodiment, early curing with an external pressure of approximately 3.0 atm after molding suppresses gas expansion and aggregation, thereby reducing foaming and optimizing the pore structure. Compared to Example 1, the material porosity is reduced to 39%, and the apparent density is increased to 1014.7 kg / m³. 3 The compressive strength was increased to 14.1 MPa. The results show that adjusting the external pressure conditions can effectively control the degree of foaming in the system, achieving a balance between the material's pore structure and mechanical properties.

[0099] In Example 24, excessive pressure leads to over-compression of the bubbles, resulting in decreased foaming efficiency and increased material density and thermal conductivity. Simultaneously, during depressurization, the compressed or trapped gas undergoes secondary expansion, easily causing pore wall rupture, microcracks, increased localized macropores and interconnected pores, leading to uneven pore structure distribution. Therefore, while excessive pressure can improve density to some extent, it weakens the lightweight insulation effect and overall structural stability.

[0100] Example 25 applied a gas pressure of 3 atm as in Example 22, but increased the wet mixing time to 10 min. Excessive mixing time causes calcium carbonate and phosphoric acid to react excessively before slurry casting. The generated bubbles escape prematurely under continuous mixing and shearing, reducing the number of fixed bubbles in the system, i.e., decreasing the solidified bubble content. This results in a decrease in the material's foaming ratio, porosity, and apparent density, weakening its lightweight insulation effect. Furthermore, prolonged mixing may destroy existing fine bubbles, worsening the uniformity of the pore structure and ultimately leading to a decline in overall performance.

[0101] Example 26: Aluminum dihydrogen phosphate produces gas slowly, and since it can also be used as an aluminum source in acid-activated polycondensation reactions, it suppresses gas expansion and aggregation under an external pressure of 3 atm, thereby reducing foaming and optimizing the pore structure. Compared to Example 1, the compressive strength is significantly improved, and the porosity is reduced. Compared to Example 22, which also uses an external pressure of 3 atm but uses phosphoric acid solution as the acid activator, the compressive strength is slightly improved, and the porosity is reduced.

[0102] Comparative Example 1, without the addition of gas-producing components, had a 28-day compressive strength of 22.8 MPa, a porosity of 25%, and an apparent density of 1528.6 kg / m³. 3 The thermal conductivity is 0.21 W / (m·K), which is significantly worse than that of Example 1.

[0103] Comparative Example 2 failed to form, highlighting the importance of different types of acid activator materials such as phosphoric acid and aluminum dihydrogen phosphate.

[0104] Comparative Example 3 also uses an acid-activated system, but it employs a pre-formed foam to introduce gas. Under strongly acidic conditions (pH=1.6), the foam formed by sodium dodecylbenzenesulfonate (SDBS) exhibits poor stability. Due to the acidic conditions and high ionic strength, the foam structure is easily damaged. During mixing, some bubbles rupture or merge, leading to uneven pore size distribution and an increased proportion of large pores. Furthermore, the pre-formed foam and acid-activated gel formation processes are asynchronous, making it difficult for bubbles to be promptly encapsulated and solidified by the gel structure, further reducing pore structure stability and adversely affecting the material's mechanical and thermal insulation properties.

[0105] Comparative Example 4 is a cement system where the reaction slurry is in an alkaline environment. Compared to the acid-activated self-foaming system, aluminum powder foaming relies on the reaction of metallic aluminum with an alkaline solution to generate hydrogen gas. This gas release process is typically more intense and significantly affected by the system's pH, temperature, and the dispersion state of the aluminum powder, making precise control difficult. The lack of synchronicity between the gas generation rate and the cement hydration process easily leads to bubbles rising, merging, or escaping before the slurry hardens, resulting in larger pore sizes and a non-uniform pore structure. This results in lower porosity and higher thermal conductivity compared to Example 15.

[0106] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for preparing acid-activated foaming materials, characterized in that, include: Acid-activated foaming material is obtained by chemically reacting raw materials including active aluminosilicate, acid activator solution, and gas-generating components. The acid activator solution contains phosphoric acid and / or acid phosphate; The gas-producing component includes materials that can react with the acid activator solution and release gas.

2. The method according to claim 1, characterized in that, The gas-producing component includes at least one of the following: normal carbonate, acidic carbonate, basic carbonate, and metal; wherein the gas-producing component satisfies at least one of the following: (1) The carbonate salt includes at least one of sodium carbonate, potassium carbonate, calcium carbonate, magnesium carbonate, zinc carbonate, basic magnesium carbonate, basic zinc carbonate, and dolomite powder; (2) The acidic carbonate includes at least one of sodium bicarbonate, potassium bicarbonate, and ammonium bicarbonate; (3) The basic carbonates include basic magnesium carbonate and / or basic zinc carbonate; (4) The metal includes at least one of aluminum, zinc, and iron; (5) The particle size of the gas-producing component is 200 mesh.

3. The method according to claim 1 or 2, characterized in that, The acid activator solution satisfies at least one of the following: (1) The acidic phosphate includes at least one of aluminum dihydrogen phosphate and potassium dihydrogen phosphate; (2) The acid activator solution contains at least one of sulfuric acid, hydrochloric acid, and organic acid; (3) At 25°C, the pH value of the acid activator solution is 1~3; (4) The solvent of the acid activator solution includes water.

4. The method according to claim 1 or 2, characterized in that, The active aluminosilicate satisfies at least one of the following: (1) The active aluminosilicate has an amorphous structure and / or a semi-crystalline structure; (2) The raw materials for the active aluminosilicate include at least one of metakaolin, fly ash, iron slag, and calcined coal gangue powder; (3) The molar ratio of silicon to aluminum in the active aluminosilicate is (1~2.5):1; (4) The molar percentage of calcium in the active aluminosilicate is less than or equal to 25%; (5) The particle size of the active aluminosilicate is 200 mesh.

5. The method according to claim 1 or 2, characterized in that, The mass ratio of the active aluminosilicate to the gas-generating component is (97~99.9):(3~0.1); and / or, The water-cement ratio in the raw materials for the chemical reaction is 0.3 to 0.

5.

6. The method according to claim 1 or 2, characterized in that, The chemical reaction includes regulating the gas pressure of the reaction environment to 2 atm to 5 atm for 2 h to 240 h, and then releasing the pressure to atmospheric pressure. And / or, The chemical reaction includes dry mixing the active aluminosilicate and the gas-generating component to obtain a powder, then adding the acid activator solution to the powder for wet mixing, the wet mixing time being less than or equal to 5 minutes, and finally allowing it to stand for 2 h to 240 h.

7. The method according to claim 1 or 2, characterized in that, The raw material for the activated aluminosilicate includes metakaolin, wherein the molar ratio of silicon to aluminum in the metakaolin is (1~2.5):1; the gas-generating component includes at least one of the following: normal carbonate, acid carbonate, basic carbonate, and metal, wherein the metal includes aluminum or zinc; the particle size of the metakaolin and the gas-generating component is such that they pass through a 200-mesh sieve, and the mass ratio of the metakaolin to the gas-generating component is (97~99.9):(3~0.1); the pH value of the acid activator solution at 25°C is 1~3; the water-cement ratio in the raw materials for the chemical reaction is 0.3~0.5; the chemical reaction includes pressure control of the reaction environment to maintain an ambient pressure of 2 atm~5 atm for 2 h~240 h, followed by depressurization to atmospheric pressure.

8. An acid-activated foaming material, characterized in that, It is prepared by a method comprising any one of claims 1 to 7 for preparing acid-activated foaming materials.

9. A component, characterized in that, It is prepared by curing treatment of the acid-activated foaming material as described in claim 8.

10. The part according to claim 9, characterized in that, The curing treatment is performed at a temperature of 20℃~30℃, a relative humidity of 40%~95%, and a duration of 2 h~240 h; and / or, The part satisfies at least one of the following: (1) Compressive strength is 1 MPa to 20 MPa; (2) Porosity is 30%~75%; (3) The apparent density is 400 kg / m³ 3 ~1200 kg / m 3 ; (4) The thermal conductivity is 0.05 W / (m·K)~0.25 W / (m·K).

Images