CN114988729A - Method for improving flexural strength of belite sulphoaluminate cement and application thereof - Google Patents
Method for improving flexural strength of belite sulphoaluminate cement and application thereof Download PDFInfo
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- CN114988729A CN114988729A CN202210741016.2A CN202210741016A CN114988729A CN 114988729 A CN114988729 A CN 114988729A CN 202210741016 A CN202210741016 A CN 202210741016A CN 114988729 A CN114988729 A CN 114988729A
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- sulphoaluminate cement
- belite sulphoaluminate
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- cement
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B7/00—Hydraulic cements
- C04B7/32—Aluminous cements
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B7/00—Hydraulic cements
- C04B7/36—Manufacture of hydraulic cements in general
- C04B7/38—Preparing or treating the raw materials individually or as batches, e.g. mixing with fuel
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P40/00—Technologies relating to the processing of minerals
- Y02P40/10—Production of cement, e.g. improving or optimising the production methods; Cement grinding
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/91—Use of waste materials as fillers for mortars or concrete
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Curing Cements, Concrete, And Artificial Stone (AREA)
Abstract
The invention discloses a method for improving the flexural strength of belite sulphoaluminate cement and application thereof, belongs to the technical field of building materials, and aims to solve the technical problem that the flexural strength of the existing belite sulphoaluminate cement is not high. The method uniformly mixes the dried activated alumina and the belite sulphoaluminate cement according to a certain mass ratio to prepare the belite sulphoaluminate cement with high flexural strength. According to the invention, the hydration process of the belite sulphoaluminate cement is influenced by regulating and controlling the technical parameters of the active alumina, the content and the characteristics of alumina gel in a hydration product are changed, the slurry structure is further optimized, the flexural strength of the cementing material is improved, and the requirement of different use environments on the flexural resistance of the belite sulphoaluminate cement hardened slurry is met.
Description
Technical Field
The invention relates to the technical field of building materials, in particular to a method for improving the flexural strength of belite sulphoaluminate cement and application thereof.
Background
The sulphoaluminate series cement has the excellent characteristics of rapid setting, low-temperature hardening, micro-expansion, freezing resistance, impermeability and the like, and is widely applied to glass fiber reinforced concrete, self-stress cement pressure pipes, ocean embankment engineering and other aspects. The belite sulphoaluminate cement developed on the basis not only inherits the advantages, but also can fully utilize various industrial waste residues in the production and hydration processes, and has the characteristics of novel green and low-carbon cementing materials. However, the belite sulphoaluminate cement has the defects of low breaking strength and even later strength collapse, and can cause damage to structural members such as beams and plates under special conditions, so that the overall structure is damaged, and the safety of lives and properties is threatened.
The common method for optimizing the performance of the belite sulphoaluminate cement is to mix limestone, slag, fly ash and other mixed materials, but the low-alkalinity environment of the belite sulphoaluminate cement slurry and the dilution effect of the mixed materials are not beneficial to the generation of secondary hydration products, so the method is easy to cause the reduction of the flexural strength of the hardened slurry. In addition, part of the research also adopts a method of adding an additive to optimize the performance of the belite sulphoaluminate cement. The publication number is: the patent of CN105646874A discloses a belite sulphoaluminate cement reinforcing agent which, although it provides a significant increase in the compressive strength of belite sulphoaluminate cement, does not increase the flexural strength much. The publication number is: the patent of CN104891839A discloses a method for improving early flexural strength (3d) of belite cement by using nano indium oxide, but later strength may be decreased. Therefore, the method has important significance for exploring a new method for effectively improving the fracture resistance of the belite sulphoaluminate cement.
The belite sulphoaluminate cement hydration products are crystal hydrated calcium sulphoaluminate and alumina gel with low crystallinity, the performance optimization of the belite sulphoaluminate cement at present focuses on the growth of the hydrated calcium sulphoaluminate, and the prospect of the alumina gel in the aspect of performance development is not paid attention to. The specific surface area of the alumina gel with low crystallinity can reach 285m 2 The viscosity and the cohesion are large, and the mechanical property of the sulphoaluminate cement stone can be improved by increasing the content of the alumina gel in the slurry (normal jun, AH, etc.) 3 And the effect of hydration on the strength of the sulphoaluminate cement, proceedings for building materials, 2016). However, the belite sulphoaluminate cement has a very limited amount of aluminium cement formed by hydration of the belite sulphoaluminate cement itself, which results in no significant improvement of the slurry properties. If the formation amount of the alumina gel in the belite sulphoaluminate cement slurry can be obviously increased, the performance of the hardened slurry can be improved. It is worth noting that the activated alumina used as the refractory material can be hydrated to form alumina gel, so that the alumina gel content in the belite sulphoaluminate cement slurry can be obviously increased by doping a proper amount of the activated alumina, and the fracture resistance of the hardened slurry is further improved.
The invention designs a method for improving the flexural strength of belite sulphoaluminate cement, which is characterized in that more activated alumina capable of being hydrated to form alumina gel is added into the belite sulphoaluminate cement, so that the slurry structure is optimized, and the improvement of the flexural resistance of the belite sulphoaluminate cement is realized.
Disclosure of Invention
The invention provides a method for improving the flexural strength of belite sulphoaluminate cement aiming at the problems in the prior art, and can solve the problem that the flexural strength of the belite sulphoaluminate cement is poor at present.
The invention provides a belite sulphoaluminate cement with high breaking strength, which comprises the following raw materials in percentage by mass: 0.5-5.0 wt% of active alumina and 95-99.5 wt% of common belite sulphoaluminate cement.
Preferably, the specific surface area of the activated alumina is 150-300m 2/kg.
Preferably, the common belite sulphoaluminate cement is a belite sulphoaluminate cement obtainable by conventional techniques or means, in particular a commercially available arctic bear belite sulphoaluminate cement.
Based on the above, the invention also provides a method for improving the flexural strength of the belite sulphoaluminate cement, which adopts the method that a proper amount of activated alumina is doped into the belite sulphoaluminate cement, so that the formation amount of alumina gel in hardening slurry is greatly increased, the slurry structure is further optimized, and the flexural strength of the hardening slurry is improved, wherein the method comprises the following steps:
s1, preparing active alumina fine powder: drying and grinding the activated alumina until the specific surface area is 150-300m2/kg to obtain activated alumina fine powder;
s2, preparing belite sulphoaluminate cement with high flexural strength: adding the fine active alumina powder into the belite sulphoaluminate cement, carrying out dry mixing in a mixer, and uniformly mixing to obtain the belite sulphoaluminate cement with high flexural strength, wherein the mass fraction of the active alumina in the belite sulphoaluminate cement with high flexural strength is 0.5-5.0%.
The invention also provides application of the method for improving the flexural strength of the belite sulphoaluminate cement in the field of preparation of sulphoaluminate series gelled materials. The mineral species of the belite sulphoaluminate cement and the sulphoaluminate cement are basically consistent, only the mineral content is different, so that the types of hydration products in the hardened slurry of the belite sulphoaluminate cement and the sulphoaluminate cement are similar, and only the product content is different, therefore, the method can also be popularized and applied to the sulphoaluminate cement.
According to the invention, a proper amount of activated alumina capable of being hydrated to form alumina gel is added into the belite sulphoaluminate cement, and the alumina gel added into the hardened slurry is beneficial to the improvement of the fracture resistance of the cement. Furthermore, the hydration process of the belite sulphoaluminate cement is influenced by controlling the technical parameters of the particle size distribution, the particle shape, the doping amount and the like of the activated alumina, the content and the characteristics of alumina gel in a hydration product are changed, the slurry structure is improved by matching with other products, the fracture resistance is improved, and the belite sulphoaluminate cement can better meet the actual application requirement.
The technical scheme of the invention has the following advantages:
1. the invention creatively designs a method for improving the flexural strength of belite sulphoaluminate cement, which changes the hydration process of belite sulphoaluminate cement and improves the content of alumina gel in a belite sulphoaluminate cement hydration product by adding activated alumina capable of hydrating to form the alumina gel. The aluminium glue that increases not only can perfect the slurry structure, is favorable to the promotion of rupture strength moreover.
2. Furthermore, the hydration process of the belite sulphoaluminate cement can be influenced by adjusting the technical parameters (particle size distribution, particle form, mixing amount and the like) of the activated alumina, the content and the characteristics of the alumina gel in the hardened slurry are greatly changed, the belite sulphoaluminate cement with different breaking strength can be obtained, and further various requirements in practical application are met.
3. The active alumina is mainly used for the production and manufacture of unshaped refractory materials at present, and the application of the active alumina in sulphoaluminate series gelled materials is not seen, so that the invention not only provides a new way for the performance optimization of the gelled materials, but also opens up a new field for the application of the active alumina.
4. Compared with the prior art, the invention provides a new idea for improving the flexural strength of the belite sulphoaluminate cement, and the technical means not only has the advantages of simple and feasible technical route, stable and good effect of improving the flexural strength, but also has important significance for popularizing the application of the activated alumina in the cementing material industry.
Detailed Description
The technical solution of the present invention is further illustrated by the following specific examples and comparative examples. It should be noted that the reagents and apparatuses of the present invention are all commercially available products unless otherwise specified.
Example 1
According to the weight percentage of 0.5 percent of active alumina doped in the belite sulphoaluminate cement, 99.5g of belite sulphoaluminate cement and 0.5 g of active alumina (the specific surface area is 300 m) 2 Kg) and mixing evenly in a mixer to obtain the belite sulphoaluminate cement with high breaking strength. The flexural strength of the cement mortar is determined according to the GB/T17671-1999 standard, and the results are shown in Table 1, and the effect of the activated alumina on improving the flexural strength is obvious.
Example 2
According to the weight percentage of 1.0 percent of active alumina doped in the belite sulphoaluminate cement, 99.0 grams of belite sulphoaluminate cement and 1.0 gram of active alumina (the specific surface area is 203 m) 2 Kg) are evenly mixed in a mixer, thus obtaining the high anti-bending agentA belite sulphoaluminate cement of strength. The flexural strength of the cement mortar is measured according to the GB/T17671-1999 standard, and the results are shown in the table 1, and the effect of the activated alumina on improving the flexural strength is obvious.
Example 3
According to the active alumina content of 3.0% in belite sulphoaluminate cement, 97.0g of belite sulphoaluminate cement and 3.0 g of active alumina (the specific surface area is 189 m) 2 And/kg) are mixed evenly in a mixer, thus obtaining the belite sulphoaluminate cement with high breaking strength. The flexural strength of the cement mortar is measured according to the GB/T17671-1999 standard, the results are shown in the table 1, and the effect of the activated alumina on improving the flexural strength is obvious.
Example 4
According to the weight percentage of 5.0 percent of active alumina doped in the belite sulphoaluminate cement, 95.0g of belite sulphoaluminate cement and 5.0g of active alumina (the specific surface area is 150 m) 2 And/kg) are mixed evenly in a mixer, thus obtaining the belite sulphoaluminate cement with high breaking strength. The flexural strength of the cement mortar is determined according to the GB/T17671-1999 standard, and the results are shown in Table 1, and the effect of the activated alumina on improving the flexural strength is good.
Comparative example 1
The flexural strength of the belite sulphoaluminate cement mortar was determined according to the GB/T17671-1999 standard and the results are shown in Table 1, the flexural strength of the hardened slurry was not high.
Comparative example 2
According to the weight fraction of 0.1 percent of active alumina doped in the belite sulphoaluminate cement, 99.9 grams of belite sulphoaluminate cement and 0.1 gram of active alumina (the specific surface area is 189 m) 2 And/kg) are mixed evenly in a mixer, and the modified belite sulphoaluminate cement can be obtained. The flexural strength of the cement mortar is determined according to the GB/T17671-1999 standard, and the results are shown in Table 1, and the effect of improving the flexural strength performance by a small amount of activated alumina is not obvious.
Comparative example 3
According to the active alumina content 10.0% doped in belite sulphoaluminate cement, taking 90.0g of belite sulphoaluminate cement and obtaining the activityAlumina 10.0 g (specific surface area 203 m) 2 And/kg) are mixed evenly in a mixer, and the modified belite sulphoaluminate cement can be obtained. The flexural strength of cement mortar was determined according to GB/T17671-1999 and the results are shown in Table 1, where a large amount of activated alumina would deteriorate the flexural strength properties.
Comparative example 4
According to the weight percentage of 0.5 percent of active alumina doped in the belite sulphoaluminate cement, 99.5g of belite sulphoaluminate cement and 0.5 g of active alumina are taken (the specific surface area is 400 m) 2 And/kg) are mixed evenly in a mixer, and the modified belite sulphoaluminate cement can be obtained. The flexural strength of the cement mortar was measured according to GB/T17671-1999 and the results are shown in Table 1, wherein the activated alumina with a large specific surface area causes a slight decrease in the flexural strength performance.
Comparative example 5
According to the weight percentage of 0.5 percent of active alumina doped in the belite sulphoaluminate cement, 99.5g of belite sulphoaluminate cement and 0.5 g of active alumina (the specific surface area is 100 m) 2 Kg) and mixing evenly in a mixer to obtain the modified belite sulphoaluminate cement. The flexural strength of the cement mortar is measured according to the GB/T17671-1999 standard, and the results are shown in Table 1, wherein the activated alumina with smaller specific surface area leads to the reduction of the early flexural strength performance and the slight increase of the later flexural strength performance.
Comparative example 6
According to the weight percentage of 0.5 percent of active alumina doped in the ordinary portland cement, 99.5g of the ordinary portland cement and 0.5 g of the active alumina (the specific surface area is 203m2/kg) are taken and mixed uniformly in a mixer, and the modified portland cement can be obtained. The flexural strength of the portland cement mortar before and after modification was determined according to the GB/T17671-1999 standard, and the flexural strength of the hardened slurry was not significantly changed, as shown in Table 2.
Table 1: flexural Strength of the products of the comparative examples and examples
Table 2: flexural strength of Portland cement
Categories | Mass fraction of activated alumina | 3d(MPa) | 7d(MPa) | 28d(MPa) |
Ordinary portland cement | 0% | 5.02 | 6.17 | 7.40 |
Comparative example 6 | 0.5% | 5.11 | 6.12 | 7.47 |
As can be seen from Table 1, the needle-like or plate-like hydrated calcium sulfoaluminate product in the belite sulphoaluminate cement slurry mainly plays a role of a skeleton, and the alumina gel with low crystallinity is further filled around the hydrated calcium sulfoaluminate to densify the slurry structure, thereby being beneficial to improving the fracture resistance. However, the amount of the alumina gel formed by the muddy hydration of the belite sulphoaluminate is limited, and the formation amount of the alumina gel in the hardened slurry can be obviously increased by doping the activated alumina which can be hydrated to form the alumina gel, so that the slurry structure is better perfected, and the breaking strength is improved. As can be seen from comparative examples 2-3, too little active alumina was added to form a small amount of alumina gel, and the flexural strength was not significantly improved, and too much active alumina was added to sharply decrease the amount of hydrated calcium sulfoaluminate acting as a skeleton, thereby deteriorating the flexural strength. As can be seen from comparative examples 4 to 5, too coarse activated alumina particles hydrate more slowly, while too fine activated alumina particles hydrate more rapidly, which is not favorable for improving the fracture resistance. Furthermore, the hydration process of the belite sulphoaluminate cement is influenced by adjusting the technical parameters (particle size distribution, particle shape, mixing amount and the like) of the activated alumina, and the content and the characteristics of the alumina gel in the hardened slurry are obviously changed, so that the belite sulphoaluminate cement with different breaking strengths is obtained, and the specific requirements in practical application are met. As can be seen from comparative example 6, the addition of activated alumina to ordinary portland cement does not significantly improve the flexural strength, because the alumina gel does not exist stably in portland cement and reacts to form the lamellar crystal hydrated gehlenite.
It should be understood that the above-described embodiments are merely examples for clearly illustrating the present invention and are not intended to limit the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications derived therefrom are intended to be within the scope of the invention.
Claims (3)
1. The belite sulphoaluminate cement with high flexural strength is characterized by comprising the following raw material components in percentage by mass: 0.5-5.0 wt% of active alumina and 95-99.5 wt% of common belite sulphoaluminate cement.
2. The belite sulphoaluminate cement of high flexural strength as claimed in claim 1, wherein the specific surface area of the activated alumina is 150-300m 2/kg.
3. The belite sulphoaluminate cement of high flexural strength according to any of claims 1 or 2, characterised in that the preparation method comprises the following steps:
s1, preparing active alumina fine powder: drying and grinding the activated alumina until the specific surface area is 150-300m2/kg to obtain activated alumina fine powder;
s2, preparing belite sulphoaluminate cement with high flexural strength: adding the active alumina fine powder into the common belite sulphoaluminate cement according to the mass percentage, and uniformly mixing in a mixer to obtain the belite sulphoaluminate cement with high flexural strength.
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CN102910852A (en) * | 2012-10-24 | 2013-02-06 | 中建商品混凝土成都有限公司 | Coagulant for super sulfate cement |
CN110386805A (en) * | 2019-08-22 | 2019-10-29 | 大连海事大学 | A kind of new sulfur aluminate-base mud/soft soil curing agent and its application method |
CN113416047A (en) * | 2021-06-29 | 2021-09-21 | 中建材中岩科技有限公司 | Sealing slurry for prefabricated building and preparation and use methods thereof |
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