Silicon carbide refractory mortar and method of making
By introducing additives such as cellulose, calcium lignosulfonate, and citric acid into silica carbide slurry and optimizing the raw material gradation, the problems of short plasticity retention time and easy damage at high temperatures in phosphate-bonded silica carbide slurry were solved. This resulted in improved stability and strength of the slurry at high temperatures and reduced defect rate in amorphous ribbon production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- WUHAN UNIV OF SCI & TECH
- Filing Date
- 2026-04-03
- Publication Date
- 2026-06-16
AI Technical Summary
Existing phosphate-bonded silica gel slurry has a short plastic retention time, is prone to swelling during drying, and is susceptible to cracking and erosion at high temperatures, leading to damage to connecting components during the production of amorphous ribbons.
Cellulose was introduced as a humectant, calcium lignosulfonate was added as a dispersant, citric acid was added as a reaction inhibitor, and the high-temperature bonding strength of the putty was optimized by rationally optimizing the silicon carbide raw material gradation, using dextrin as a plasticizer, and adding aluminum dihydrogen phosphate as a binder.
It improves the high-temperature bonding strength and volume stability of silicon carbide refractory mortar, extends the workable time, reduces the swelling and cracking of mortar at high temperatures, enhances erosion resistance, and reduces the defect rate of amorphous ribbon production.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of refractory materials technology, specifically to a silicon carbide refractory mortar and its preparation method. Background Technology
[0002] Currently, in the domestic and international amorphous ribbon manufacturing processes, silicon carbide putty is used for bonding components such as sprues, spray cups, and nozzles. To ensure the safety and efficiency of the production process and the stability of the amorphous ribbon quality, silicon carbide putty is required to have good plasticity, high bonding strength, good high-temperature volume stability, and excellent high-temperature corrosion resistance.
[0003] Silicon carbide refractory mortar is typically composed of silicon carbide raw materials (granules and fine powders), binders (phosphates, aluminates, resins, etc.), and additives (plasticizers, dispersants, antioxidants, etc.). Among these, phosphate-bonded systems exhibit high high-temperature strength due to the formation of an AlPO4 binding phase at high temperatures, and silicon carbide refractory mortars made from these binders are widely used in high-temperature applications such as amorphous ribbon fabrication. For example, patent CN113800916A discloses a phosphate-bonded pre-laid silicon carbide refractory mortar, prepared from silicon carbide and its dust extraction powder, silicon nitride, elemental silicon, and alumina powder. This mortar has a long construction time, hardens quickly at room temperature after laying, and exhibits high room-temperature bonding strength, meeting on-site hoisting requirements and improving construction efficiency and safety. Furthermore, this mortar demonstrates high high-temperature bonding strength and good high-temperature performance.
[0004] However, in practical applications, existing phosphate-bonded silica gel putty suffers from several problems. The putty hardens and loses plasticity after being mixed with the binder and left for a period of time, resulting in a short workability period and difficulty in maintaining plasticity. Furthermore, during the heating and drying process after application, the binder reacts with iron impurities in the raw materials to produce hydrogen gas, causing the putty to swell and peel off. Additionally, during high-temperature use, the volume effect causes cracking and damage to connecting components. In strip production, the putty is easily eroded or washed away by high-temperature melts, resulting in severe damage. Summary of the Invention
[0005] To address the problems of short plasticity retention time, easy bulging during drying, easy cracking at high temperatures, and poor erosion resistance in phosphate-bonded silica carbide refractory mortar, this invention provides a silica carbide refractory mortar and its preparation method. This invention introduces cellulose as a humectant, adds calcium lignosulfonate as a dispersant, adds citric acid as a reaction inhibitor, and simultaneously uses cellulose and dextrin as plasticizers, adds aluminum dihydrogen phosphate as a binder, and improves the high-temperature bonding strength of the silica carbide refractory mortar by rationally optimizing the gradation of the silica carbide raw materials and introducing smaller particle size silica carbide micropowder as a high-temperature accelerator.
[0006] To achieve the above objectives, the technical solution of the present invention is as follows.
[0007] This invention provides a silicon carbide refractory mortar, which is prepared by mixing refractory mortar powder, a binder, and composite additives. The refractory mortar powder is prepared from the following components by mass fraction: 80%–90% silicon carbide, 7%–12% Suzhou clay, and 3%–8% alumina micropowder, totaling 100%. The particle size distribution of the silicon carbide is: 1%–5% 1000 mesh, 3%–8% 600 mesh, 10%–30% 325 mesh, 40%–60% 180 mesh, 5%–10% 60 mesh, and 5%–10% 35 mesh. The binder is aluminum dihydrogen phosphate solution. The composite additives are prepared by mixing a dispersant, a humectant, a reaction inhibitor, and a plasticizer. The dispersant is calcium lignosulfonate; the humectant is carboxymethyl cellulose; the reaction inhibitor is citric acid; and the plasticizer is dextrin.
[0008] Preferably, the binder accounts for 20% to 35% of the total mass of the refractory mortar powder.
[0009] Preferably, the composite additive accounts for 0.4% to 5% of the total mass of the refractory mortar powder.
[0010] Preferably, the mass ratio of dispersant, humectant, reaction inhibitor and plasticizer is 1:1:0.8:2.
[0011] Preferably, the dispersant accounts for 0.1% to 1% of the mass of the refractory mortar powder; the humectant accounts for 0.1% to 1% of the mass of the refractory mortar powder; the reaction inhibitor accounts for 0.1% to 1% of the mass of the refractory mortar powder; and the plasticizer accounts for 0.1% to 2% of the mass of the refractory mortar powder.
[0012] Preferably, the Suzhou clay has a mesh size of 180-240. Suzhou clay can improve the plasticity of refractory mortar, facilitate the construction of refractory mortar, and under high temperature, it mullite-forms a mullite network structure, providing high-temperature strength to the refractory mortar.
[0013] Preferably, the alumina powder is 300-400 mesh. The alumina powder can fill the pores of the refractory mortar, enhancing its density. Furthermore, the alumina powder can react with the remaining silica from Suzhou Tumulai Petrochemical at high temperatures to further generate mullite, thereby improving the high-temperature bonding strength of the refractory mortar.
[0014] Preferably, the mass concentration of aluminum dihydrogen phosphate is 50%.
[0015] This invention also provides a method for preparing silicon carbide refractory mortar, comprising the following steps: Silicon carbide, Suzhou clay, alumina powder and composite additives are mixed evenly, a binder is added and mixing is continued. After discharge, the material is sealed and trapped for 24 hours to obtain silicon carbide refractory mortar.
[0016] The beneficial effects of this invention are: 1. This invention introduces cellulose, which has good water absorption, to form a stable colloidal network with strong water-locking ability; the addition of calcium lignosulfonate allows it to be adsorbed onto the surface of solid particles, generating electrostatic repulsion and improving the dispersibility of solid particles; the addition of citric acid can form a chelate with iron impurities in silicon carbide raw materials, inhibiting the reaction between the binder and impurities; the polyhydroxy structure and hydrophilicity of dextrin are utilized to improve the plasticity of the mortar; aluminum dihydrogen phosphate is added as a binder, and the particle size distribution of silicon carbide raw materials is rationally designed, introducing smaller-diameter silicon carbide micropowder as a high-temperature sintering accelerator; and mullite is formed after a certain proportion of Suzhou clay and alumina micropowder reacts at high temperature, optimizing the composition and structure of the refractory mortar at high temperatures and improving the high-temperature bonding strength and volume stability of the silica gel mortar.
[0017] 2. The plasticity of the silicon carbide refractory mortar prepared by this invention is significantly improved, and the plasticity index of the mortar does not decrease significantly after 24 hours; the bonding strength is significantly improved, and the erosion resistance is enhanced; the defect rate of the produced amorphous ribbon due to the quality of the mortar is significantly reduced. Detailed Implementation
[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.
[0019] Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0020] The technical solution of the present invention will be further described below through specific embodiments.
[0021] In the following embodiments, unless otherwise specified, the methods described are conventional methods; and unless otherwise specified, the reagents and materials described are commercially available.
[0022] Example 1 A method for preparing a silicon carbide refractory mortar includes the following steps: Weigh the mixed raw materials according to the proportions in Example 1 in Table 1: The refractory mortar powder consists of 83% silicon carbide, 12% Suzhou clay, and 5% alumina micro powder, totaling 100%.
[0023] The particle size distribution of the silicon carbide is: 1000 mesh 2%, 600 mesh 3%, 325 mesh 12%, 180 mesh 56%, 60 mesh 5%, and 35 mesh 5%, based on the total mass of the refractory mortar powder.
[0024] The binder is 28% aluminum dihydrogen phosphate, based on the total mass of the refractory mortar powder.
[0025] The composite additive is composed of 0.5% calcium lignosulfonate, 0.5% carboxymethyl cellulose, 0.3% citric acid, and 1% dextrin, based on the total mass of the refractory mortar powder.
[0026] Silicon carbide, Suzhou clay, alumina micro powder and composite additives were added to a ball mill and dry-mixed evenly. The ball milling process parameters were: ball-to-material ratio 4:1, rotation speed 300 r / min, and mixing time 40 min.
[0027] The well-mixed powder was transferred to a mixer, and aluminum dihydrogen phosphate solution was added for wet mixing. After discharge, the powder was sealed in a plastic bag and left to stand for 24 hours to obtain silicon carbide refractory mortar.
[0028] Examples 2 to 5 Examples 2 to 5 are prepared in the same way as Example 1, except that the raw material ratios are different. The specific ratios are shown in Table 1.
[0029] Table 1. Raw material ratios for preparing silicon carbide refractory mortar in Examples 1-5 Note: "-" indicates no data. Comparative Example 1 A method for preparing a silicon carbide refractory mortar includes the following steps: Weigh the raw materials according to the following ratio: Refractory mortar powder consists of 85% silicon carbide, 10% clay powder, and 5% high alumina powder, totaling 100%.
[0030] The particle size distribution of the silicon carbide is: 20% 325 mesh, 40% 180 mesh, 15% 60 mesh, and 10% 35 mesh, based on the total mass of the refractory mortar powder.
[0031] The added binder accounts for 20% to 35% of the total mass of the refractory mortar powder, and the dispersant sodium tripolyphosphate accounts for 0.5% of the total mass of the refractory mortar powder.
[0032] Silicon carbide, clay powder, high alumina powder and dispersant were added to a ball mill and mixed evenly. The ball milling process parameters were: ball-to-material ratio 4:1, rotation speed 300 r / min, and mixing time 40 min.
[0033] The well-mixed powder was transferred to a mixer, a binder was added and the mixture was continued for 20 minutes. After discharge, the powder was placed in a plastic bag and sealed for 24 hours to obtain silicon carbide refractory mortar.
[0034] Performance testing: Relevant performance tests were conducted on the silicon carbide refractory mortars prepared in Examples 1 to 5, as well as the silicon carbide refractory mortars prepared in Comparative Example 1. The details are as follows: (1) The bond strength shall be tested in accordance with GB / T 22459.9-2024 Refractory Mortar Part 9: Test Method for Shear Bond Strength at Room Temperature; (2) The linear change rate was determined in accordance with GB / T 5988-2022 Test Method for Permanent Linear Change of Refractory Materials under Heating.
[0035] The test results for the above test content are shown in Table 2 below: Table 2 Performance indicators of the carbonized silica gel mud prepared in the examples Results Analysis: As shown in Table 2 above, the silicon carbide refractory mortar prepared in this embodiment of the invention exhibits the lowest absolute value of linear change rate (0.11%) and the highest bonding strength (12.5 MPa) after heat treatment at 1250℃ for 3 hours. This indicates that the silicon carbide refractory mortar prepared in this invention has good high-temperature volume stability and excellent high-temperature bonding performance. It does not show significant volume change or performance degradation after heating, and the product quality is stable. In the comparative example, no reaction inhibitors, humectants, or plasticizers were added. The bonding strength of the samples was lower. After 2 hours of stirring, the mortar clearly dried, its plasticity decreased significantly, and it was difficult to apply. During drying after application, the mortar swelled and peeled off. Due to the low bonding strength, the mortar was severely damaged by molten metal erosion during high-temperature use.
[0036] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A silicon carbide refractory mortar, characterized in that, The silicon carbide refractory mortar is prepared by mixing refractory mortar powder, binder and composite additives. The refractory mortar powder is prepared from the following components by mass fraction: 80%–90% silicon carbide, 7%–12% Suzhou clay, and 3%–8% alumina micro powder, totaling 100%. The particle size distribution of the silicon carbide is as follows: 1000 mesh 1%–5%, 600 mesh 3%–8%, 325 mesh 10%–30%, 180 mesh 40%–60%, 60 mesh 5%–10%, and 35 mesh 5%–10%. The binder is aluminum dihydrogen phosphate solution; the composite additive is obtained by mixing a dispersant, a humectant, a reaction inhibitor, and a plasticizer; the dispersant is calcium lignosulfonate; the humectant is carboxymethyl cellulose; the reaction inhibitor is citric acid; and the plasticizer is dextrin.
2. The silicon carbide refractory mortar according to claim 1, characterized in that, The binder accounts for 20% to 35% of the total mass of the refractory mortar powder.
3. The silicon carbide refractory mortar according to claim 1, characterized in that, The composite additive accounts for 0.4% to 5% of the total mass of the refractory mortar powder.
4. The silicon carbide refractory mortar according to claim 1, characterized in that, The mass ratio of dispersant, humectant, reaction inhibitor and plasticizer is 1:1:0.8:
2.
5. The silicon carbide refractory mortar according to claim 1, characterized in that, The dispersant accounts for 0.1% to 1% of the mass of the refractory mortar powder; the humectant accounts for 0.1% to 1% of the mass of the refractory mortar powder; the reaction inhibitor accounts for 0.1% to 1% of the mass of the refractory mortar powder; and the plasticizer accounts for 0.1% to 2% of the mass of the refractory mortar powder.
6. The silicon carbide refractory mortar according to claim 1, characterized in that, The Suzhou soil in question has a mesh size of 180-240.
7. The silicon carbide refractory mortar according to claim 1, characterized in that, The alumina powder is 300-400 mesh.
8. The silicon carbide refractory mortar according to claim 1, characterized in that, The mass concentration of aluminum dihydrogen phosphate is 50%.
9. A method for preparing silicon carbide refractory mortar as described in claim 1, characterized in that, Includes the following steps: Silicon carbide, Suzhou clay, alumina powder and composite additives are mixed evenly, a binder is added and mixing is continued. After discharge, the material is sealed and trapped for 24 hours to obtain silicon carbide refractory mortar.