Mortar composition, impact-resistant structure, and method for producing impact-resistant structure

Abstract

The purpose of the present invention is to provide a mortar composition which has improved impact absorbing properties compared to mortar in the prior art, an impact-resistant structure in which the mortar composition is used, and a method for producing the impact-resistant structure. Provided is a mortar composition that has impact absorbing properties. The mortar composition is characterized by comprising hollow particles and a main raw material which is constituted by one or more types of compositions including mortar, wherein the amount of the hollow particles added is 5-30 mass%. The particle size of the hollow particles is 0.2-1 mm. The bulk density of the hollow particles may be 0.1-1.0 g / cm3. Also provided is an impact-resistant structure 10 wherein the mortar composition is disposed in a gap between a nozzle 20 of a continuous casting device and a metal case 30 which is disposed around the nozzle 20.<sp / >

Description

Mortar composition, impact-resistant structure, and method for manufacturing an impact-resistant structure

[0001] The present invention relates to a mortar composition, an impact-resistant structure, and a method for manufacturing an impact-resistant structure.

[0002] Conventionally, as disclosed in Patent Document 1, a technology has been provided to alleviate stress concentration in a continuous casting nozzle and suppress its downward slippage. Specifically, Patent Document 1 proposes a configuration in which a tapered portion and a horizontal portion are provided in the flange portion of the nozzle body, and these portions are supported by a metal case with mortar interposed therein, thereby reducing stress concentration and suppressing the downward slippage of the nozzle. This technology is expected to alleviate stress concentration in the neck portion and improve the efficiency of nozzle replacement work during continuous casting.

[0003] Japanese Patent Publication No. 2024-071220

[0004] However, the technology described in Patent Document 1 may not adequately relieve the stress caused by mechanical impacts in the mortar between the nozzle and the metal case. In particular, in continuous casting processes where shocks and vibrations frequently occur in high-temperature environments, there is a concern that buckling or breakage of the mortar may occur, leading to displacement or cracking of the nozzle body. Furthermore, the configuration of the conventional technology described in Patent Document 1 has insufficient shock absorption performance, which may affect the lifespan of the continuous casting equipment and the casting quality.

[0005] Therefore, the present invention aims to provide a mortar composition that offers improved shock absorption compared to conventional mortars, an impact-resistant structure using the mortar composition, and a method for manufacturing the impact-resistant structure.

[0006] (1) The mortar composition of the present invention has shock absorption properties and is characterized by comprising hollow particles and a main raw material consisting of one or more compositions including mortar, wherein the amount of hollow particles added is 5 to 30 mass%.

[0007] The mortar composition of the present invention, by having the configuration described in (1) above, forms voids within the mortar due to the addition of hollow particles, thereby improving its shock absorption performance. Furthermore, the mortar composition of the present invention has a hollow particle addition amount of 5 to 30 mass%. As a result, the mortar composition of the present invention ensures a good balance of the overall shock absorption performance of the mortar, achieving both durability and shock absorption.

[0008] (2) The mortar composition of the present invention is preferably characterized in that the particle size of the hollow particles is 0.2 mm or more and 1 mm or less.

[0009] As described in (2) above, the mortar composition of the present invention allows for uniform dispersion of hollow particles in the mortar by controlling the particle size between 0.2 mm and 1 mm. This ensures that the impact absorption effect is uniformly exerted throughout the mortar, and is expected to alleviate stress generated in the mortar. As a result, the impact resistance of the mortar composition is improved, and stable performance can be maintained even with long-term use.

[0010] (3) The mortar composition of the present invention has a bulk density of 0.1 g / cm³ of hollow particles. ３ Above, 1.0g / cm ３ It is preferable that it be characterized by the following:

[0011] The mortar composition of the present invention has a bulk density of hollow particles of 0.1 g / cm³ as described in (3) above. ３ Above, 1.0g / cm ３ By following the conditions below, impact energy can be effectively absorbed. Furthermore, by appropriately setting the range of bulk density, excellent impact resistance can be achieved without compromising impact absorption capabilities.

[0012] (4) The mortar composition of the present invention may be such that the hollow particles are selected from perlite, shirasu balloons, or fly ash balloons.

[0013] As described in (4) above, the mortar composition of the present invention can achieve excellent shock absorption by selecting hollow particles of perlite, shirasu balloons, or fly ash balloons. These hollow particles each have many voids inside and efficiently absorb impact energy, thereby enhancing the shock absorption performance of the mortar. Furthermore, the performance can be adjusted to suit the application depending on the type of hollow particle selected.

[0014] (5) The mortar composition of the present invention is preferably characterized by containing an inorganic binder or an organic binder as a binder. Inorganic binders, organic binders, or mixtures thereof can be suitably used as binders. Suitable inorganic binders include, for example, sodium silicate, potassium silicate, sodium phosphate, colloidal silica, or mixtures thereof. Suitable organic binders include, for example, phenolic resins, hydrolysates of sugars and / or reduced starch syrups, molasses, methylcellulose, starch, natural rubber, casein, vinyl acetate, or mixtures thereof.

[0015] The mortar composition of the present invention can be adapted to the usage environment by using an inorganic binder or an organic binder as described in (5) above. The mortar composition of the present invention is fluid during application and hardens before heating (after drying). By using an inorganic binder, the mortar composition of the present invention can have high adhesive strength and maintain adhesive strength even in high-temperature environments. Furthermore, when a resin binder is used as the organic binder in the mortar composition of the present invention, the strength after hardening is high and can maintain strength while transitioning from resin bonding to carbon bonding as the temperature rises. Furthermore, when a plastic binder is used as the organic binder in the mortar composition of the present invention, a ceramic bond is formed by firing at high temperatures, and sufficient strength can be obtained. In this way, the properties of the mortar composition of the present invention can be optimized by selecting the binder, so it can be used for a variety of applications.

[0016] (6) The impact-resistant structure of the present invention uses the mortar composition of the present invention described above, characterized in that the mortar composition is placed in the gap between the nozzle of a continuous casting apparatus and a metal case arranged around the nozzle.

[0017] As described in (6) above, the impact-resistant structure of the present invention can effectively absorb mechanical shocks and prevent damage to the nozzle by placing the mortar composition of the present invention between the nozzle and the metal case in a continuous casting apparatus. Furthermore, the impact-resistant structure of the present invention improves the cushioning effect between the nozzle and the metal case due to the shock-absorbing properties of the mortar composition, suppressing damage to the nozzle and enabling stable casting operations.

[0018] (7) The method for manufacturing the impact-resistant structure of the present invention is such that the impact-resistant structure is made by placing a mortar composition in the gap between the nozzle of a continuous casting apparatus and a metal case arranged around the nozzle, and is characterized in that the mortar composition of the present invention is used as the mortar composition.

[0019] As described in (7) above, the method for manufacturing the impact-resistant structure of the present invention allows for the production of a structure with uniform and high impact resistance by appropriately filling the gap between the nozzle and the metal case with a mortar composition. This improves construction accuracy and ensures uniform impact absorption performance, thereby effectively mitigating mechanical stress during continuous casting and suppressing nozzle damage.

[0020] According to the present invention, it is possible to provide a mortar composition, an impact-resistant structure, and a method for manufacturing an impact-resistant structure that solve the above-mentioned problems.

[0021] This is an explanatory diagram showing an impact-resistant structure according to one embodiment of the present invention. This is a photograph showing a test specimen for the drop ball test prepared in the example. This is an explanatory diagram schematically showing the test method for the drop ball test carried out in the example. This is an explanatory diagram showing the relationship between the damage state and score of the drop ball test specimen in the drop ball test carried out in the example. This is an explanatory diagram showing an overview of the drop weight impact testing machine used in the drop weight impact test carried out in the example. These are a cross-section, micrograph, and SEM image of the sample prepared in the example. This is a graph showing the results of the drop ball test in the example, where 10 test specimens were used for each sample, and the average score of the damage state was calculated based on the evaluation criteria in Figure 4. This is a graph showing the average value of the drop ball mark diameter formed on the surface of the mortar composition when a steel ball hit it in the drop ball test carried out in the example. This is a graph showing the correlation between the evaluation score and the drop ball mark diameter in the drop ball test carried out in the example. This shows the relationship between the test specimen and the rebound height of the steel ball after the drop ball test carried out in the example. This graph shows the index of the maximum load for each sample before and after heating, with the maximum load value during the first drop of weight on sample A set to 100, as shown in the example. This graph shows the rate of decrease in the thickness of the test specimen after the drop of weight impact test performed in the example. These are photographs of the test specimen after the drop of weight impact test performed in the example, and the state 40 ms after the striker hit the test specimen during the first drop of weight.

[0022] The following describes a mortar composition, an impact-resistant structure 10, and a method for manufacturing the impact-resistant structure 10 according to one embodiment of the present invention.

[0023] <Mortar Composition> The mortar composition of this embodiment is used, for example, as a joint when setting a metal case onto a refractory nozzle in other components such as a continuous casting nozzle used in a continuous casting apparatus, and is used to improve their impact resistance. The mortar composition of this embodiment comprises hollow particles and a main raw material consisting of one or more compositions including mortar.

[0024] Mortar serves as a base material that provides fire resistance and strength. For example, refractory mortar specified in the Japanese Industrial Standards (JIS R2501) can be used, and it is preferable to use refractory mortar of types 1 to 4 specified in the said standard. By using high-alumina mortar as the main raw material, stable performance can be achieved even in high-temperature environments. As a result, the mortar composition of the present invention is suitable for equipment used in high-temperature environments such as continuous casting.

[0025] Hollow particles are components that improve the overall impact resistance of the mortar composition by absorbing impact. Preferably, perlite, shirasu balloons, and fly ash balloons are selected as the hollow particles. Because these hollow particles have a structure with fine voids inside, they can effectively absorb impact energy and mitigate impact. Furthermore, the performance can be adjusted to suit the application depending on the type of hollow particle selected.

[0026] The particle size of the hollow particles should ideally be between 0.2 mm and 1 mm. If the particle size exceeds 1 mm, the dispersion in the mortar may become uneven, potentially reducing the impact absorption capacity. Conversely, if the particle size is less than 0.2 mm, a void structure that effectively absorbs impact may not be secured, and the impact absorption effect may not be fully realized. Therefore, by setting the particle size between 0.2 mm and 1 mm, the hollow particles can be uniformly dispersed in the mortar composition, resulting in stable impact resistance.

[0027] Furthermore, the bulk density of the hollow particles is 1.0 g / cm³. ３ Preferably, the bulk density is 1.0 g / cm³. ３ If it exceeds this value, the void structure may not be secured, and the shock absorption effect may not be fully realized. Conversely, 1.0 g / cm³ ３ By doing the following, it is possible to provide a mortar composition that exhibits high performance without compromising shock absorption. By controlling the bulk density in this way, the balance between the overall weight of the mortar composition and its shock absorption can be adjusted.

[0028] The amount of hollow particles added should preferably be between 5 and 30 mass%. If the amount added is less than 5 mass%, the effective shock absorption of the hollow particles cannot be obtained, and the impact resistance of the mortar composition will not be sufficiently improved. On the other hand, if it exceeds 30 mass%, the overall strength of the mortar will decrease, and its durability may be impaired. Therefore, by adding hollow particles in the range of 5 to 30 mass%, a composition that balances shock absorption and mortar strength can be achieved.

[0029] For the binder, either an inorganic binder or an organic binder may be used. Using an inorganic binder improves the refractory properties of the mortar composition in high-temperature environments, making it suitable for use at high temperatures such as in continuous casting. When a resin binder is used as the organic binder, it provides high strength after curing, and maintains its strength while transitioning from resin bonding to carbon bonding as the temperature rises. When a plastic binder is used, ceramic bonds are formed by firing at high temperatures, providing sufficient strength. In this way, by selecting the appropriate binder according to the usage environment and application, it is possible to optimize the performance of the mortar composition.

[0030] As described above, the mortar composition of this embodiment exhibits excellent impact resistance by appropriately controlling the type, particle size, bulk density, and amount of hollow particles, and by combining it with high-alumina mortar and binders. As a result, the mortar composition can suppress damage to nozzles used under high-temperature and harsh conditions such as continuous casting. Furthermore, the lighter weight of the mortar composition reduces the burden of handling and construction.

[0031] <<Impact-Resistant Structure 10>> As shown in Figure 1, the impact-resistant structure 10 of this embodiment is constructed by placing an impact-resistant part 40 made of a mortar composition in the gap between the nozzle 20 and the metal case 30 in the continuous casting apparatus. The continuous casting apparatus is equipped with a nozzle 20 for supplying molten metal to the mold, and the nozzle 20 has an opening that allows high-temperature molten metal to pass through during the casting process.

[0032] The metal case 30 is a component that supports the nozzle 20 from the outside and ensures its stability. By being positioned around the nozzle 20, the metal case 30 is provided to act as a refractory material while also mitigating external pressure, thermal, and mechanical shocks acting on the nozzle 20.

[0033] The mortar composition forming the impact-resistant section 40 is uniformly filled between the nozzle 20 and the metal case 30. By placing the mortar composition forming the impact-resistant section 40 in this gap, the mechanical impact generated between the nozzle 20 and the metal case 30 can be effectively absorbed and stress can be relieved.

[0034] In the impact-resistant structure 10, the mortar composition used as the impact-resistant part 40 is preferably made of hollow particles selected from perlite, shirasu balloons, or fly ash balloons, as described above. These hollow particles have a fine void structure and are highly effective in mitigating impact. Furthermore, if high-alumina mortar is used as the main component of the mortar composition, the high-alumina mortar provides fire resistance and exhibits stable performance even in the high-temperature environment of continuous casting. For this reason, the impact-resistant structure 10 can effectively mitigate the thermal and mechanical impacts that occur between the nozzle 20 and the metal case 30.

[0035] The mortar composition forming the impact-resistant section 40 has optimally adjusted particle size, bulk density, and additive amount, resulting in high impact absorption performance and improved protection for the nozzle. Specifically, the impact-resistant section 40 has a particle size of 0.2 mm or more and 1 mm or less of hollow particles contained in the mortar composition, thereby dispersing the hollow particles almost uniformly within the mortar composition and mitigating the stress acting on it. Furthermore, the impact-resistant section 40 has a bulk density of 1.0 g / cm³ of hollow particles contained in the mortar composition. ３ By doing the following, it is possible to reduce the weight load on the nozzle while maintaining high shock absorption.

[0036] Further, by setting the addition amount of hollow particles contained in the mortar composition of the impact-resistant part 40 to 5 to 30 mass%, it is possible to ensure a good balance between the impact absorption ability and the strength of the entire mortar composition. Thus, by including an appropriate amount of hollow particles in the mortar composition, the impact-resistant part 40 can efficiently absorb the impact generated in the gap between the nozzle and the metal case and can exhibit durability against repeated impacts.

[0037] In the impact-resistant structure 10 of the present embodiment, by using an inorganic binder or a resin binder in the mortar composition forming the impact-resistant part 40, it is possible to have adaptability according to the use environment. For example, when an inorganic binder is used, the fire resistance in a high-temperature environment such as continuous casting is improved. On the other hand, when a resin binder is used, the flexibility is increased and the deformation absorption ability when receiving an impact is improved. Thus, by selecting the binder, the impact-resistant structure 10 can cope with various use conditions.

[0038] By configuring the impact-resistant structure 10 as described above, in the impact-resistant part 40 provided in the gap between the nozzle 20 and the metal case 30 of the continuous casting apparatus, thermal and mechanical impacts can be effectively absorbed and mitigated. Thereby, the occurrence of cracks and damage in the nozzle 20 can be suppressed, and the life of the nozzle 20 can be extended. Further, the impact-resistant structure 10 suppresses the transmission of impact through the metal case 30, improves the durability of the nozzle, and enables stable continuous casting.

[0039] ≪Method for Manufacturing the Impact-Resistant Structure 10≫ Next, the method for manufacturing the impact-resistant structure 10 will be described. The method for manufacturing the impact-resistant structure 10 includes the step of forming an impact-resistant section 40 by placing a mortar composition between the nozzle 20 and the metal case 30 of a continuous casting apparatus. The mortar composition used in the manufacture of the impact-resistant structure 10 is prepared using hollow particles and a main raw material consisting of one or more raw materials including mortar such as high-alumina mortar, as described above. The impact-resistant structure 10 is manufactured by appropriately filling the gap between the nozzle 20 and the metal case 30 with the mortar composition. The method for manufacturing the impact-resistant structure 10 will be described in detail step by step below.

[0040] (Mortar Composition Preparation Process) The mortar composition preparation process is a process of preparing a mortar composition to be filled into the gap between the nozzle 20 and the metal case 30. In the mortar composition preparation process, hollow particles and mortar (for example, high-alumina mortar) are first mixed to prepare a uniform mortar composition. It is preferable to use perlite, shirasu balloons, or fly ash balloons as the hollow particles, as these hollow particles contribute to improving the shock absorption of the mortar composition. Furthermore, by controlling the particle size of the mortar composition to be between 0.2 mm and 1 mm, the dispersibility when filling into the gap is improved, and a mortar layer of uniform density can be formed throughout the gap.

[0041] Furthermore, when preparing the mortar composition, either an inorganic binder or an organic binder is used as the binder. When an inorganic binder is used, the mortar remains stable even in high-temperature environments, and its refractory properties during continuous casting are improved. In contrast, when a resin binder is used as the organic binder, the strength is high after hardening, and it has high durability even before heating.

[0042] (Mortar Composition Filling Step) Next, the prepared mortar composition is applied to the outer periphery of the nozzle 20 of the continuous casting apparatus, and the metal case 30 is attached, thereby uniformly filling the space between the nozzle 20 and the metal case 30. At this time, since the particle size of the hollow particles in the mortar composition is 0.2 mm or more and 1 mm or less, the composition is firmly filled into the gap while maintaining fluidity. As a result, workability is improved, and the generation of bubbles and non-uniform filling can be prevented.

[0043] (Shock-Resistant Part Forming Step) By curing the mortar composition filled in the above-described mortar composition filling step, a shock-resistant part 40 is formed. The curing in the shock-resistant part forming step proceeds by different mechanisms depending on the type of binder used. When an inorganic binder (such as sodium silicate, potassium silicate, sodium phosphate, colloidal silica, etc.) is used, it cures by a chemical reaction of these inorganic substances. When a resin binder is used as an organic binder, strength is exhibited by a chemical curing reaction of the resin. When a plastic binder is used, strength is exhibited by the generation of a ceramic bond in the firing step after drying. In the shock-resistant part forming step, a predetermined time (for example, about 24 to 48 hours) is required for the mortar composition to obtain a predetermined strength. In the shock-resistant part forming step, appropriate curing conditions may be set according to the type of binder used. When an inorganic binder is used, appropriate environmental conditions (temperature, humidity, etc.) may be maintained to promote the reaction. When a resin binder is used, curing conditions (temperature, time, etc.) suitable for the resin are set. When a plastic binder is used, after appropriate drying conditions, a firing step at a predetermined temperature may be performed. When the mortar composition is cured in this way, a shock-resistant part 40 is formed in the space between the nozzle 20 and the metal case 30.

[0044] When the shock-resistant part 40 is formed in the above-described shock-resistant part forming step, the shock-resistant structure 10 is completed. As a result, the shock-resistant part 40 formed between the nozzle 20 and the metal case 30 can effectively absorb mechanical shocks from the outside and is expected to have the effect of alleviating the transmission of shocks.

[0045] As described above, the impact-resistant structure 10 manufactured in the above-described manner can effectively relieve the mechanical stress applied to the nozzle 20 of the continuous casting apparatus, prevent cracks and breakage of the nozzle 20, and suppress damage to the nozzle. Further, the impact-resistant structure 10 has high resistance to temperature fluctuations and vibrations around the nozzle 20, and it is possible to realize stable continuous casting. By filling the mortar composition substantially uniformly between the nozzle 20 and the metal case 30 and curing it before heating to form the impact-resistant portion 40, the impact-resistant structure 10 can be provided with excellent impact resistance and durability.

[0046] <<Function and Effect>> (a) The mortar composition of the present embodiment has impact absorption characteristics, and includes hollow particles and a main raw material composed of one or more compositions including mortar, and the addition amount of the hollow particles is 5 to 30 mass%, and is characterized in that.

[0047] By configuring the mortar composition of the present embodiment as in (a) above, voids are formed in the mortar due to the addition of the hollow particles, thereby improving the impact absorption performance. Further, the mortar composition of the present embodiment has an addition amount of hollow particles of 5 to 30 mass%. Thereby, the mortar composition of the present embodiment can ensure the impact absorption performance of the entire mortar in a balanced manner and achieve both durability and impact absorption.

[0048] (b) The mortar composition of the present embodiment is characterized in that the particle size of the hollow particles is 0.2 mm or more and 1 mm or less. [[ID=eleven]]

[0049] By controlling the particle size of the hollow particles to 0.2 mm or more and 1 mm or less as in (b) above, the mortar composition of the present embodiment can be uniformly dispersed in the mortar. As a result, the impact absorption effect is evenly exhibited over the entire mortar, and the stress can be relieved. As a result, the impact resistance of the mortar composition is improved, and stable performance can be exhibited even after long-term use.

[0050] (c) The mortar composition of the present embodiment is characterized in that the bulk density of the hollow particles is 0.1 g / cm ３ or more and 1.0 g / cm ３ or less.

[0051] The mortar composition of this embodiment has a bulk density of hollow particles of 0.1 g / cm³ as described in (c) above. ３ Above, 1.0g / cm ３ By implementing the following, the impact absorption can be improved. By using lightweight hollow particles, the weight of the mortar composition can be reduced while effectively absorbing impact energy. Furthermore, by appropriately setting the range of bulk density, excellent impact resistance can be achieved without compromising impact absorption capacity.

[0052] (d) The mortar composition of this embodiment is characterized in that the hollow particles are selected from perlite, shirasu balloons, or fly ash balloons.

[0053] The mortar composition of this embodiment can achieve excellent shock absorption and lightness by selecting hollow particles of perlite, shirasu balloons, or fly ash balloons, as described in (d) above. These hollow particles each have many voids inside and efficiently absorb impact energy, thereby enhancing the shock absorption performance of the mortar. Furthermore, the performance can be adjusted to suit the application depending on the type of hollow particle selected.

[0054] (e) The mortar composition of this embodiment is characterized by containing an inorganic binder or an organic binder as a binder.

[0055] The mortar composition of this embodiment can be adapted to the usage environment by using an inorganic binder or an organic binder as described in (e) above. The mortar composition of the present invention is fluid during application and hardens before heating (after drying). By using an inorganic binder, the mortar composition of this embodiment can have high adhesive strength and maintain adhesive strength even in high-temperature environments. Furthermore, when a resin binder is used as the organic binder in the mortar composition of this embodiment, the strength after hardening is high, and the strength can be maintained while transitioning from resin bonding to carbon bonding as the temperature rises. Furthermore, when a plastic binder is used as the organic binder in the mortar composition of the present invention, a ceramic bond is formed by firing at high temperatures, and sufficient strength can be obtained. In this way, the properties of the mortar composition of this embodiment can be optimized by selecting the binder, so it can be used for a variety of applications.

[0056] (f) The impact-resistant structure 10 of this embodiment uses the mortar composition of this embodiment described above, and the mortar composition is placed in the gap between the nozzle 20 of the continuous casting apparatus and the metal case 30 arranged around the nozzle 20.

[0057] As described in (f) above, the impact-resistant structure 10 of this embodiment can effectively absorb mechanical shocks and prevent damage to the nozzle 20 and metal case 30 by placing the mortar composition of this embodiment between the nozzle 20 and the metal case 30 in a continuous casting apparatus. Furthermore, the impact-resistant structure 10 of this embodiment improves the cushioning effect between the nozzle 20 and the metal case 30 due to the shock-absorbing properties of the mortar composition, extending the life of the nozzle and enabling stable casting operations.

[0058] (g) The manufacturing method of the impact-resistant structure 10 of this embodiment is such that the impact-resistant structure 10 is made by placing a mortar composition in the gap between the nozzle 20 of the continuous casting apparatus and the metal case 30 arranged around the nozzle 20, and the mortar composition of this embodiment is used as the mortar composition.

[0059] The manufacturing method for the impact-resistant structure 10 of this embodiment, as described in (g) above, involves appropriately filling the gap between the nozzle 20 and the metal case 30 with a mortar composition, thereby enabling the production of a structure 10 with uniform and high impact resistance. This improves construction accuracy and ensures uniform impact absorption performance, effectively mitigating mechanical stress during continuous casting and suppressing damage to the nozzle 20.

[0060] An impact absorption evaluation test was conducted on a mortar composition according to one embodiment of the present invention. The method for preparing the test sample used in the evaluation test, the method for evaluating impact absorption, and the results of the impact absorption evaluation will be described below.

[0061] ≪Method for Preparing Test Samples≫ The test samples in this example were prepared by pouring a mortar composition containing hollow particles in the proportions shown in Table 1 into a mold, curing it for 24 hours, and then drying it at 80°C for 24 hours. A high-alumina mortar composition was used, and perlite with a particle size of 0.7 mm or less was used as the hollow particles. Samples were prepared both after drying and after heating at 900°C for 4 hours after drying. This made it possible to evaluate the changes in the properties of the samples with and without heating.

[0062]

[0063] ≪Method for Evaluating Impact Absorption≫ While Charpy tests, drop weight tests, and drop ball tests are commonly used as impact load tests for refractories, in this example, the drop ball test and drop weight impact test were used for evaluation. This test was conducted to evaluate the differences in impact absorption caused by hollow particles added to the mortar composition.

[0064] In the drop ball test, as shown in Figure 2, a 44 x 44 x 5 mm sample was placed on a 60 x 60 x 15 mm refractory material, and a backing material 8 mm wide and 5 mm thick was attached around the sample to prepare the specimen for the drop ball test. Graphite-silicon carbide was used as the refractory material. As shown in Figure 3, a steel ball (JIS B 1501 standard) with a diameter of 50 mm and a weight of 509 g was dropped onto the specimen from a height of 1800 mm, and the state of damage to the refractory material was observed. The state of damage was divided into five stages, as shown in Figure 4, and a score of 5 to 1 point was assigned to each stage. Each sample was tested 10 times, and the impact absorption performance was evaluated based on the average state of damage.

[0065] In the drop weight impact test, a 40 x 40 x 10 mm sample was prepared and used as the test specimen. To prevent scattering, the test specimen was placed in a 100 x 70 mm poly bag with several small holes, and the test was conducted using a drop weight impact testing machine (Imatek Systems Ltd, IM10T-40HV). Figure 5 shows an overview of the drop weight impact testing machine. In the test, a striker with a drop weight of 10.34 kg or 12.34 kg and a diameter of 80 mm was dropped onto the test specimen from a height of 150 mm, and the impact absorption performance was evaluated by measuring the maximum load applied to the load cell.

[0066] The striker was dropped three times on the same specimen, and the fragments of the specimen that broke after each drop were removed before continuing the test. Furthermore, the thickness of the specimen was measured after each drop to evaluate the change in impact absorption in detail. This test allowed us to investigate the effects of the amount of hollow particles added and whether or not heating was used on impact absorption.

[0067] As described above, in this example, the properties of mortar compositions containing hollow particles were thoroughly investigated through the preparation of test samples and evaluation of their impact absorption. This allowed us to identify the optimal composition of mortar for improving impact absorption.

[0068] Next, we will explain the observation results of the sample prepared in this embodiment, as well as the evaluation results of its shock absorption properties.

[0069] <<Sample Observation>> In the examples, the test samples were observed to investigate the changes in the internal structure when hollow particles were added to the mortar composition. The samples were observed both before and after heat treatment, and were analyzed in detail using cross-sections, micrographs, and SEM (scanning electron microscope) images.

[0070] Figure 6 shows cross-sections, micrographs, and SEM images of the prepared samples. Regardless of whether the samples were heated or not, the samples with added hollow particles showed a significantly larger number of voids compared to the samples with only the mortar composition. These voids were formed by the dispersion of the hollow particles within the mortar composition, suggesting improved shock absorption due to the hollow structure.

[0071] Observation of the sample before heating confirmed that the addition of hollow particles created uniform voids within the mortar composition. In particular, microscopic images showed that perlite was uniformly distributed throughout the mortar composition, suggesting that this uniformly improved the overall shock absorption. Furthermore, SEM images also showed that the perlite particles were encased in the surrounding mortar matrix, which is thought to have the effect of dispersing energy when an impact is applied.

[0072] Observation of the sample after heating confirmed that the hollow particles in the mortar composition were stable against heat after heat treatment at 900°C for 4 hours. Microscopic and SEM images showed that the hollow particles remained intact without deformation or collapse even after heating, demonstrating that it functions as a highly fire-resistant shock absorber in continuous casting applications where fire resistance is required. Furthermore, it is presumed that the crystalline structure of the mortar composition matrix itself was densified by the heat treatment, improving the overall strength.

[0073] From the above sample observations, it was confirmed that the voids formed in the mortar composition by the addition of hollow particles contribute to shock absorption. Furthermore, it was revealed that the structure of the hollow particles is maintained even after heating, resulting in stable performance even in the high-temperature environment of continuous casting. As a result, mortar compositions containing hollow particles can be applied between metal cases and nozzles as a material that combines fire resistance and shock absorption.

[0074] ≪Ball Drop Test≫ In this embodiment, a ball drop test was conducted to evaluate the impact absorption of a sample of mortar composition with added hollow particles. In the ball drop test, a 44 x 44 x 5 mm mortar composition sample was placed on a 60 x 60 x 15 mm refractory material, and a backing material with a width of 8 mm and a thickness of 5 mm was attached around the sample. A steel ball with a diameter of 50 mm and a weight of 509 g, conforming to JIS B 1501 standards, was dropped onto this sample from a height of 1800 mm, and the state of damage to the refractory material was observed.

[0075] The impact absorption performance of the samples was evaluated by classifying the state of damage to the refractory material after the steel ball impact into five stages, and assigning a score of 1 to 5 points to each stage. Based on the evaluation criteria shown in Figure 4, tests were conducted using 10 specimens for each sample, and the average damage state was evaluated. Figure 7 shows the results of the evaluation scores, and Figure 8 shows the average diameter of the ball impact marks formed on the surface of the mortar composition.

[0076] The test results showed that, both before and after heating, the greater the amount of hollow particles added to the mortar composition, the less damage the refractory material sustained and the higher its shock absorption. Specifically, sample C, with 20 mass% of hollow particles added, scored the highest, followed by sample B with 10 mass%, and then sample A, which had no hollow particles added. This indicates that the more hollow particles added, the better the shock absorption of the mortar composition.

[0077] Furthermore, as shown in Figure 8, a tendency was observed for the diameter of the ball drop to increase with higher scores. This indicates that samples containing many hollow particles have a high ability to elastically deform the surface of the mortar composition when subjected to impact, thereby absorbing energy. As shown in Figure 9, there was a high correlation between the evaluation score and the diameter of the ball drop, confirming that samples with larger ball drop diameters had higher impact absorption.

[0078] Furthermore, as shown in Figure 10, observation of the rebound height of the steel ball from the test specimen after the test revealed a tendency for samples with higher scores to have lower rebound heights. This indicates that when the mortar composition was subjected to impact, it absorbed some of the energy internally, reducing the rebound energy. However, the rebound height and the order of scores did not always perfectly coincide, which is thought to be due to the damage to the test specimen and the deformation of the refractory material contributing to the absorption of impact energy.

[0079] When comparing the rebound height of samples before and after heating, the rebound height decreased in the order of increasing hollow particle content in both cases. In particular, sample C, which contained 20 mass% hollow particles, had the lowest rebound height both before and after heating, indicating high shock absorption. This result suggests that adding hollow particles allows the mortar composition to effectively absorb energy when subjected to impact.

[0080] From the above results, it has become clear that the mortar composition of the present invention can have its shock absorption properties improved by increasing the amount of hollow particles added. Furthermore, it was confirmed that the high shock absorption performance is maintained even after heat treatment due to the effect of the hollow particles. This proves that the mortar composition can exhibit excellent shock absorption even in high-temperature environments such as continuous casting equipment.

[0081] ≪Results of Drop Weight Impact Test≫ In this embodiment, a drop weight impact test was conducted to further evaluate the impact absorption of the sample in which hollow particles were added to the mortar composition. In the drop weight impact test, a sample measuring 40 × 40 × 10 mm was used as the test specimen, and to prevent scattering, the test specimen was placed in a 100 × 70 mm poly bag with several small holes. For the test, a drop weight impact testing machine (Imatek Systems Ltd, IM10T-40HV) was used, and impacts were applied to the test specimen using a striker with a drop weight of 10.34 kg and 12.34 kg and a diameter of 80 mm.

[0082] In the drop-weight impact test, the impact absorption capacity of the specimen was evaluated by dropping a striker from a height of 150 mm onto the specimen and measuring the maximum load applied to the load cell. The striker drop was repeated three times on the same specimen, and the test continued while removing the fragments of the specimen that broke off after each drop. In addition, the thickness of the specimen was measured after each drop to evaluate the degree to which the specimen was compressed by the impact.

[0083] Figure 11 shows the results for maximum load. A smaller maximum load indicates higher shock absorption, and the index was set to 100, based on the maximum load during the first drop of the weight for sample A before and after heating. In the test with a drop weight of 10.34 kg, sample C, which had 20 mass% of hollow particles added, showed the highest shock absorption both before and after heating, followed by sample B with 10 mass%, and then sample A, which did not contain hollow particles. In the test with a drop weight of 12.34 kg, the maximum load decreased in the order of A > B > C before and after heating, indicating that each sample had a high ability to absorb the impact applied to it.

[0084] Figure 12 shows the percentage decrease in specimen thickness after each drop weight test. When a specimen is subjected to impact, its thickness decreases, and compression and deformation occur. It was observed that the smaller the maximum load, the greater the percentage decrease in thickness. This indicates that the specimen has a high ability to elastically deform and absorb energy internally when subjected to impact. In particular, sample C, which contains 20 mass% hollow particles, showed the largest percentage decrease in thickness both before and after heating, confirming its high impact absorption capacity.

[0085] Figure 13 shows the specimen after testing and its state 40 ms after the striker struck the specimen during the first drop of weight. From the test results, different behaviors were observed in sample B before heating in the tests with drop weights of 10.34 kg and 12.34 kg. Specifically, in the case of a drop weight of 10.34 kg, the specimen largely retained its shape even after three drops, but in the case of a drop weight of 12.34 kg, most of it had shattered. This indicates that the fracture behavior of the mortar composition differs depending on the magnitude of the impact applied to the specimen.

[0086] Of the samples A, B, and C before and after heating, sample C before heating showed that the specimen was mostly shattered, while sample C after heating was completely shattered. On the other hand, although chipping was observed on the outer edges of samples A and B after heating, the specimens as a whole maintained their shape. These results indicate that samples containing many hollow particles have a mechanism to mitigate impact by absorbing energy internally and shattering when subjected to impact.

[0087] Furthermore, observation of the striker's rebound height after 40 ms revealed a tendency for samples with smaller maximum loads to exhibit lower rebound heights. This indicates that the samples efficiently absorbed energy upon impact, resulting in reduced rebound energy. Additionally, with a drop weight of 10.34 kg, the rebound heights of samples A and B before heating were almost identical, confirming the effectiveness of samples with added hollow particles that exhibit superior shock absorption.

[0088] These results demonstrate that by adding hollow particles to the mortar composition of the present invention, the energy of the impact on the test specimen can be effectively absorbed internally. Furthermore, it was revealed that the impact absorption properties are maintained even after heating, providing an impact-resistant structure that can withstand use in high-temperature environments. In this way, by appropriately adding hollow particles to the mortar composition, it is possible to effectively mitigate the mechanical impacts generated in continuous casting equipment and extend the life of the nozzle.

[0089] ≪Summary≫ Based on the results of this embodiment, it was confirmed that the shock absorption properties of the mortar composition placed between the refractory material and the metal case can be improved by adding hollow particles. It was found that the addition of hollow particles creates numerous voids in the mortar composition, and these voids play a role in absorbing and mitigating impact energy.

[0090] The results of the ball drop test and the weight drop impact test showed that the impact absorption of the sample increased as the amount of hollow particles added increased. This is because the presence of hollow particles allows the mortar composition to effectively absorb energy when subjected to impact. In particular, the sample with 20 mass% of hollow particles added showed the highest impact absorption compared to the other samples.

[0091] However, it was observed that increasing the amount of hollow particles added tended to make the mortar composition itself more brittle. Mortar compositions absorb impact by crumbling when subjected to force, and this involves the fracture behavior of the mortar composition. Therefore, if the mortar composition is too brittle between the refractory material and the metal case, an impact could create a gap, potentially causing the metal case to detach. For this reason, it is important to appropriately select the amount of hollow particles added according to the actual environment in which it will be used.

[0092] Furthermore, the results of the drop weight impact test suggested that within the load range where the mortar composition does not crumble, sufficient impact absorption cannot be obtained even with the addition of hollow particles. Therefore, selecting the amount of hollow particles to add according to the load expected during use is an important factor in the effective utilization of the mortar composition.

[0093] From the above results, it has been confirmed that the mortar composition of the present invention has the effect of improving shock absorption when used between refractory materials and metal cases. By appropriately selecting hollow particles and adjusting the amount added, a good balance between shock resistance and durability can be ensured, contributing to the protection of nozzles and suppression of nozzle damage in continuous casting equipment. This makes it possible to provide an effective means for achieving stable production in the continuous casting process.

[0094] The present invention is not limited to the configurations described in the embodiments above, and can be modified as appropriate without departing from the scope of the technical idea of ​​the present invention. The components of each embodiment described above may be arbitrarily selected and combined. Furthermore, the components of each embodiment may be arbitrarily combined with any components described in the means for solving the problem, the form for carrying out the invention, etc., or components that embody any components described in the means for solving the problem, the form for carrying out the invention, etc. The applicant intends to obtain rights for these as well in this application or in divisional applications, amendment applications, etc. based on this application.

[0095] The mortar composition, impact-resistant structure, and method for manufacturing the impact-resistant structure of the present invention can be suitably used in a wide range of applications where impact resistance is required, such as filling the gap between the nozzle of a continuous casting apparatus and a metal case arranged around the nozzle.

[0096] 10 Impact-resistant structure 20 Nozzle 30 Metal case

Claims

1. A mortar composition having shock-absorbing properties, comprising hollow particles and a main raw material consisting of one or more compositions including mortar, wherein the amount of hollow particles added is 5 to 30 mass%.

2. The mortar composition according to claim 1 or 2, characterized in that the particle size of the hollow particles is 0.2 mm or more and 1 mm or less.

3. The bulk density of the hollow particles is 0.1 g / cm³. ３ Above, 1.0g / cm ３ The mortar composition according to claim 1 or 2, characterized in that it is as follows:

4. The mortar composition according to claim 1, characterized in that the hollow particles are selected from perlite, shirasu balloons, or fly ash balloons.

5. The mortar composition according to claim 1 or 2, characterized in that it contains an inorganic binder or an organic binder as a binder.

6. An impact-resistant structure using the mortar composition according to claim 1 or 2, characterized in that the mortar composition is placed in the gap between the nozzle of a continuous casting apparatus and a metal case arranged around the nozzle.

7. A method for manufacturing an impact-resistant structure, wherein the impact-resistant structure is for which a mortar composition is placed in the gap between a nozzle of a continuous casting apparatus and a metal case arranged around the nozzle, and the mortar composition is the mortar composition described in claim 1 or 2, as described in claim 7.

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