LU102639B1 - A strontium ferrite-based self-compacting sacrificial paste and its preparation method - Google Patents

A strontium ferrite-based self-compacting sacrificial paste and its preparation method Download PDF

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Publication number
LU102639B1
LU102639B1 LU102639A LU102639A LU102639B1 LU 102639 B1 LU102639 B1 LU 102639B1 LU 102639 A LU102639 A LU 102639A LU 102639 A LU102639 A LU 102639A LU 102639 B1 LU102639 B1 LU 102639B1
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Luxembourg
Prior art keywords
strontium ferrite
compacting
water
based self
parts
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Application number
LU102639A
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French (fr)
Inventor
Jianjian Qin
Li Gao
Kaijian Huang
Huan Zhao
Hongyan Chu
Jiancheng Zhang
Jinyang Jiang
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Univ Nanjing Forestry
Univ Southeast
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Priority to LU102639A priority Critical patent/LU102639B1/en
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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
    • C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
    • C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
    • C04B28/06—Aluminous cements
    • C04B28/065—Calcium aluminosulfate cements, e.g. cements hydrating into ettringite
    • 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
    • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
    • C04B2111/00034—Physico-chemical characteristics of the mixtures
    • C04B2111/00103—Self-compacting mixtures
    • 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
    • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
    • C04B2111/00241—Physical properties of the materials not provided for elsewhere in C04B2111/00
    • C04B2111/00258—Electromagnetic wave absorbing or shielding materials

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Inorganic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Organic Chemistry (AREA)
  • Preparation Of Clay, And Manufacture Of Mixtures Containing Clay Or Cement (AREA)

Abstract

The invention discloses a strontium ferrite-based self-compacting sacrificial paste and its preparation method, the strontium ferrite-based self-compacting sacrificial paste mainly comprises 1000-1600 parts of sulphoaluminate cement, 130-500 parts of strontium ferrite, 620-660 parts of water and 0.05-30 parts of superplasticizer. The preparation process is simple, and the strontium ferrite-based sacrificial paste with self-compacting performance can be prepared by using a conventional forced single horizontal shaft concrete mixer. The obtained paste has excellent working performance, compressive strength and corrosion resistance. It can be used in the current third and future fourth generation nuclear power plant core catchers, and has obvious engineering application value.

Description

Description LU102639 A strontium ferrite-based self-compacting sacrificial paste and its preparation method
TECHNICAL FIELD The invention relates to the technical field of nuclear power materials, especially refers to a strontium ferrite-based self-compacting sacrificial paste and its preparation method.
BACKGROUND In order to improve the severe accident mitigation ability of nuclear power plants, core catchers are usually used for collecting, cooling and solidifying core melts in the third generation nuclear power technology. In case of severe nuclear accident, the sacrificial material in the core catcher interacts with the core melt. The temperature of core melt is about 3000-4000°C, while the melting temperature of cement-based sacrificial material in contact with it is only about 1100°C, which leads to the erosion of sacrificial material in core catcher. If the sacrificial materials of the core catcher are exhausted, the core melt will continue to erode the bottom plate of the containment. If the bottom plate of the containment is melted through, the containment will lose its integrity, resulting in leakage of radioactive materials. Therefore, the cooling and solidification of core melt is the key to reduce the catastrophic accident of nuclear power plants. As the core component of the core catcher, sacrificial materials play a decisive role in the cooling and solidification of the core melt. At present, scholars from China and other countries have disclosed the preparation technology of sacrificial materials. Generally speaking, the sacrificial materials prepared at present have low efficiency in cooling and solidifying the core melt. 1
Description LU102639 Strontium ferrite is a permanent magnetic material with excellent magnetism. Due to the similarity in time between the decomposition temperature of strontium ferrite and the activation temperature of the interaction between core melt and sacrificial material, strontium ferrite has more advantages in cooling and solidification of core melt. However, there is no report on the preparation of self-compacting sacrificial materials with strontium ferrite.
SUMMARY Purpose of the invention: In order to solve the problems in the existing technologies, the purpose of the invention is to offer a strontium ferrite-based self-compacting sacrificial paste and its preparation method. Technical scheme: In order to achieve the above purpose, the invention discloses a strontium ferrite-based self-compacting sacrificial paste and its preparation method, the material is mainly prepared from the following raw materials in parts by weight: 1000-1600 parts of sulphoaluminate cement; 130-500 parts of strontium ferrite; 620-660 parts of water; 0.05-30 parts of superplasticizer. The sulphoaluminate cement is 42.5 grade sulphoaluminate cement, in which CaO content is higher than 40%, and Al»O3 content is higher than 20%. The strontium ferrite is in powder form, wherein the content of SrFe12019 is not less than 95%. The water is tap water or drinking water which meets the requirements of Water Standard for Concrete (JGI 63-2006). The superplasticizer is polycarboxylate superplasticizer with colorless to light yellow appearance, density of 1.05-1.15g/ml, solid content not less than 40% (mass content), air 2
Description LU102639 content of 6-8% (volume content), pH value of 6-8, and water reducing rate is not less than 33%.
The preparation method of the strontium ferrite-based self-compacting sacrificial paste, including: (1) Taking 42.5 grade sulphoaluminate cement and strontium ferrite powder, and mixing uniformly in dry condition to obtain a mixed material M1; (2) Adding a mixed solution of water and superplasticizer into the uniformly mixed material M1, and stirring to obtain a uniformly mixed material M2, thus obtaining the strontium ferrite-based self-compacting sacrificial paste. In step (1), adding various raw materials used for mixing into a forced single horizontal shaft concrete mixer, wherein the mixing speed is selected to be 40-50 revolutions per minute and the mixing time is selected to be 180-200 seconds; In step (2), first, 1/2 water is mixed with all the superplasticizer, then the evenly mixed solution is added into the mixed material MI, then the container containing the superplasticizer is cleaned with the remaining water, and then the water is added into the mixed material M1 after cleaning, and the mixing time is 180-200 seconds. Comparing with the existing technologies, the strontium ferrite-based self-compacting sacrificial paste prepared by the invention has very good working performance, and the slump flow of the strontium ferrite-based self-compacting sacrificial paste is greater than 160mm, thus meeting the requirement of self-compacting fluidity; Its compressive strength is greater than 35MPa, which is improved by more than 15% compared with the requirements of the existing technologies; Comparing with the existing technologies, its 3
Description LU102639 decomposition enthalpy is improved by more than 15%, which can greatly reduce the erosion rate of sacrificial materials and improve the safety of nuclear power plants. Technical effects: The preparation process is simple, and the strontium ferrite-based sacrificial paste with self-compacting performance can be prepared by using a conventional forced single horizontal shaft concrete mixer. The strontium ferrite-based self-compacting sacrificial paste prepared by the invention has very good working performance and is convenient for engineering construction; The compressive strength of the material has been greatly improved, which can improve its durability and prolong its service life; The decomposition enthalpy of the material is significantly improved, which leads to a significant decrease in the corrosion rate and an improvement in corrosion resistance, thus improving the safety of nuclear power plants. Therefore, the method has obvious engineering application value.
DESCRIPTION OF THE INVENTION The present invention will be further illustrated with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. After reading the present invention, various modifications of equivalent forms made by those technicians in the technical field should be under the protection scope defined by the appended claims of this application. In addition, the advantages of the present invention are emphasized by comparing the experimental results of the embodiments. The raw materials used in the following embodiments meet the following requirements: The cement is 42.5 grade sulphoaluminate cement, in which CaO content is 42.6%, and Al>O3z content is 22.5%.
4
Description LU102639 The content of SrFe12019 in the strontium ferrite powder is 96.3%. The water is tap water. The superplasticizer is polycarboxylate superplasticizer with light yellow appearance, density of 1.10g/ml, solid content not less than 41.2% (mass content), air content of 7% (volume content), pH value of 7.2, and water reducing rate is 33.5%. Embodiment 1 A strontium ferrite-based self-compacting sacrificial paste comprises the following components in parts by weight: 1440 parts of sulphoaluminate cement; 160 parts of strontium ferrite; 640 parts of water;
0.24 parts of superplasticizer. Preparation method: (1) Weighing required materials, including sulphoaluminate cement, strontium ferrite powder, tap water and superplasticizer; (2) Wetting mixer and all necessary tools and moulds with water; (3) The weighed sulphoaluminate cement and strontium ferrite powder are added to the forced single horizontal shaft concrete mixer in turn. The mixing speed is 45 revolutions per minute and the mixing time is 180 seconds. The mixed material M1 is obtained by mixing evenly; (4) First, 1/2 of water is mixed with all the superplasticizer, and then the mixed solution is added into the mixture M1. Then the remaining water is used to clean the container containing the superplasticizer. After cleaning, the remaining water is added to the mixture M1. After 180 seconds of mixing, the mixture M2 is obtained, and then the molding and curing are carried out according to Chinese national standards.
Description LU102639 Embodiment 2 A strontium ferrite-based self-compacting sacrificial paste comprises the following components in parts by weight: 1280 parts of sulphoaluminate cement; 320 parts of strontium ferrite; 640 parts of water;
0.96 parts of superplasticizer. Preparation method: (1) Weighing required materials, including sulphoaluminate cement, strontium ferrite powder, tap water and superplasticizer; (2) Wetting mixer and all necessary tools and moulds with water; (3) The weighed sulphoaluminate cement and strontium ferrite powder are added to the forced single horizontal shaft concrete mixer in turn. The mixing speed is 45 revolutions per minute and the mixing time is 180 seconds. The mixed material M1 is obtained by mixing evenly; (4) First, 1/2 of water is mixed with all the superplasticizer, and then the mixed solution is added into the mixture M1. Then the remaining water is used to clean the container containing the superplasticizer. After cleaning, the remaining water is added to the mixture M1. After 180 seconds of mixing, the mixture M2 is obtained, and then the molding and curing are carried out according to Chinese national standards. Embodiment 3 A strontium ferrite-based self-compacting sacrificial paste comprises the following components in parts by weight: 1120 parts of sulphoaluminate cement; 480 parts of strontium ferrite; 640 parts of water;
25.6 parts of superplasticizer.
6
Description LU102639 Preparation method: (1) Weighing required materials, including sulphoaluminate cement, strontium ferrite powder, tap water and superplasticizer; (2) Wetting mixer and all necessary tools and moulds with water; (3) The weighed sulphoaluminate cement and strontium ferrite powder are added to the forced single horizontal shaft concrete mixer in turn. The mixing speed is 45 revolutions per minute and the mixing time is 180 seconds. The mixed material M1 is obtained by mixing evenly; (4) First, 1/2 of water is mixed with all the superplasticizer, and then the mixed solution is added into the mixture M1. Then the remaining water is used to clean the container containing the superplasticizer. After cleaning, the remaining water is added to the mixture M1. After 180 seconds of mixing, the mixture M2 is obtained, and then the molding and curing are carried out according to Chinese national standards. The above three embodiments have the same preparation process. The differences are as follows: 1440 parts of sulphoaluminate cement and 160 parts of strontium ferrite in Embodiment 1, 1280 parts of sulphoaluminate cement and 320 parts of strontium ferrite in Embodiment 2, 1120 parts of sulphoaluminate cement and 480 parts of strontium ferrite in Embodiment 3. The sum of the mass of sulphoaluminate cement and strontium ferrite in the three embodiments is 1600 parts, while the mass of strontium ferrite in the three embodiments increases in turn; The water in all three embodiments was 640 parts, which remained unchanged; In order to make the prepared strontium ferrite-based sacrificial paste achieve self-compacting performance, the dosage of superplasticizer in the three embodiments is very different.
7
Description LU102639 Performance testing According to Chinese national standard GB/T 14902-2012, the working performance of the strontium ferrite-based self-compacting sacrificial paste in the above embodiments was tested, and the measurement index was slump flow. According to Chinese national standard GB/T 50107-2010, the 28-day compressive strength of strontium ferrite-based self-compacting sacrificial paste was tested. The enthalpy of strontium ferrite-based self- compacting sacrificial paste was tested by thermogravimetric analysis, and the decomposition temperature was tested by high temperature experiment. The decomposition enthalpy of strontium ferrite-based self-compacting sacrificial paste was obtained by combining the two experiments. The experimental results of the three embodiments are shown in Table 1. Table 1 Experimental results strength (MPa) enthalpy (J/kg) It can be seen from Table 1 that the slump flow of the three embodiments is greater than 160mm, which meets the requirements of self-compacting performance. With the increase of strontium ferrite content, the 28-day compressive strength of strontium ferrite- based self-compacting sacrificial paste gradually decreases, but the minimum strength is
35.6MPa, which is still 18.7% higher than the technical requirement of 30MPa. With the increase of strontium ferrite content, the decomposition enthalpy of strontium ferrite- based self-compacting sacrificial paste gradually increases, which indicates that the corrosion rate gradually decreases, thus improving the safety of nuclear power plants. 8
Description LU102639 In addition, it should be noted that the above embodiments are only used to illustrate the technical scheme of the present invention. If the technical embodiment of the present invention is modified or replaced by an ordinary technician in the technical field without departing from the purpose of the present invention, it shall be covered in the protection scope of the claims of the present invention. The following explains why the decomposition enthalpy of strontium ferrite-based self- compacting sacrificial paste increases, which leads to the decrease of its corrosion rate: According to the heat conduction theory, the relationship between the erosion rate of strontium ferrite-based self-compacting sacrificial paste and the heat flux transferred to its interior is shown in the following formula: V=0/(pxAx AH) (1) In the above formula, V is the erosion rate of strontium ferrite-based self-compacting sacrificial paste, Q is the heat flux transferred to the interior of strontium ferrite-based self-compacting sacrificial paste, A is the erosion area of strontium ferrite-based self- compacting sacrificial paste, and AH is the decomposition enthalpy of strontium ferrite- based self-compacting sacrificial paste. It can be seen from the above formula (1) that the erosion rate of strontium ferrite-based self-compacting sacrificial paste is inversely proportional to its decomposition enthalpy. This indicates that when the decomposition enthalpy of strontium ferrite-based self- compacting sacrificial paste increases, the corrosion rate decreases.
9

Claims (6)

Claims LU102639
1. A strontium ferrite-based self-compacting sacrificial paste, which is characterized by that the material is mainly prepared from the following raw materials in parts by weight: 1000-1600 parts of sulphoaluminate cement; 130-500 parts of strontium ferrite; 620-660 parts of water; 0.05-30 parts of superplasticizer; The preparation method including: (1) Mixing 42.5 grade sulphoaluminate cement and strontium ferrite powder, and mixing evenly in dry condition to obtain mixed material M1; (2) Adding a mixed solution of water and superplasticizer into the uniformly mixed material M1, and stirring to obtain a uniformly mixed material M2, thus obtaining the strontium ferrite-based self-compacting sacrificial paste.
2. A strontium ferrite-based self-compacting sacrificial paste according to Claim 1, which is characterized by that the cement is 42.5 grade sulphoaluminate cement, in which CaO content is higher than 42%, and Al»O3 content is higher than 20%.
3. A strontium ferrite-based self-compacting sacrificial paste according to Claim 1, which is characterized by that the strontium ferrite is in powder form, wherein the content of SrFe12O19 is not less than 95%.
4. A strontium ferrite-based self-compacting sacrificial paste according to Claim 1, which is characterized by that the water is tap water or drinking water which meets the requirements of Water Standard for Concrete (JGJ 63-2006).
5. A strontium ferrite-based self-compacting sacrificial paste according to Claim 1, which is characterized by that the superplasticizer is polycarboxylate superplasticizer with colorless to light yellow appearance, density of 1.05-1.15g/ml. Specifically, solid content
Claims LU102639 is not less than 40% (by mass percentage), gas content is 6-8% (by volume), pH value is 6-8, and water reducing rate is not less than 33%.
6. The preparation method of the strontium ferrite-based self-compacting sacrificial paste according to Claim 1, which is characterized by that in step (1), adding various raw materials used for mixing into a forced single horizontal shaft concrete mixer, wherein the mixing speed is selected to be 40-50 revolutions per minute and the mixing time is selected to be 180-200 seconds; In step (2), first, 1/2 water is mixed with all the superplasticizer, then the evenly mixed solution is added into the mixed material MI, then the container containing the superplasticizer is cleaned with the remaining water, and then the water is added into the mixed material M1 after cleaning, and the mixing time is 180-200 seconds.
11
LU102639A 2021-03-10 2021-03-10 A strontium ferrite-based self-compacting sacrificial paste and its preparation method LU102639B1 (en)

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Effective date: 20210910