CN117756484A - Cement adhesive for rapidly testing strength of porcelain insulator porcelain piece, and preparation method and application thereof - Google Patents

Abstract

The invention provides a cement adhesive for rapid strength testing of porcelain insulators and its preparation method and application. The cement adhesive includes the following components in weight percentage: 40-60wt% aluminate cement, 30-50wt% artificial porcelain sand, 2-5wt% halloysite and 1-5wt% silica powder, so The cement adhesive also includes an externally mixed anti-cracking agent, water-reducing agent, quick-drying agent and defoaming agent. The external mixing amounts of the anti-cracking agent, water-reducing agent, quick-drying agent and defoaming agent are respectively 0.1~ 0.3wt%, 0.1~0.3wt%, 0.1~0.5wt% and 0.1~0.3wt%. The cement adhesive greatly shortens the cycle of strength testing of porcelain insulators, from the current testing time of 7 days to 1 day.

Description

A kind of cement adhesive for rapid testing of the strength of porcelain insulators and its preparation method and application

Technical field

The invention relates to the technical field of electric power ultra-high voltage, and in particular to a cement adhesive for rapid testing of the strength of porcelain parts of porcelain insulators and its preparation method and application.

Background technique

In the State Grid's ultra-high voltage and ultra-high voltage projects, composite insulators, glass insulators and porcelain insulators are generally used. Among them, porcelain insulators are widely used in UHV projects due to their excellent corrosion resistance and high strength. Compared with the other two insulators, its unique performance greatly ensures the safety and reliability of UHV line projects. Porcelain insulators are mainly composed of porcelain parts, cement adhesive and hardware. During the production process, in order to test whether the strength of porcelain parts is qualified, it is often necessary to glue cement glue into them. After 7 days of curing, when the strength of the cement glue increases to above 90MPa, the mechanical properties of the porcelain parts are tested. If the cement glue If the strength of the mixture is too low, the glue will often break and the porcelain piece will break, which cannot truly reflect the actual strength of the porcelain piece. The main reason is that the cement adhesive is made of Portland cement as the cementing material, plus filling materials such as river sand or quartz sand and water. To achieve a strength of 90MPa, sufficient curing time is required, which generally requires 7 days or more. long time. In addition, lead-tin alloy is melted and poured directly, but the preparation process is relatively complicated, and this process is almost no longer used in actual factories. Therefore, Portland cement adhesive is currently the most widely used.

At present, the cement adhesive used for porcelain insulation testing must reach 90MPa or above, and is often cured for 7 days or longer. In the manufacturing process of porcelain insulators, the cycle for testing the strength of porcelain parts is too long, which affects the product delivery cycle and thus affects to production efficiency. Therefore, it is particularly necessary to further shorten the testing period for the strength of porcelain parts.

Contents of the invention

In order to solve the above technical problems, the present invention provides a cement adhesive for rapid testing of the strength of porcelain parts of porcelain insulators and a preparation method and application thereof. The cement adhesive greatly shortens the cycle of strength testing of porcelain insulators, from the current testing time of 7 days to 1 day.

In order to achieve the above objects, the technical solutions adopted by the present invention are:

A cement adhesive for rapid testing of the strength of porcelain parts of porcelain insulators. The cement adhesive includes the following components in weight percentage: 40 to 60 wt% aluminate cement, 30 to 50 wt% artificial porcelain sand, 2 to 5 wt% Halloysite and 1 to 5 wt% silica powder, the cement adhesive also includes external anti-cracking agent, water-reducing agent, quick-drying agent and defoaming agent, the anti-cracking agent, water-reducing agent, quick-drying agent The external dosage of dry agent and defoaming agent are 0.1~0.3wt%, 0.1~0.3wt%, 0.1~0.5wt% and 0.1~0.3wt% respectively.

Preferably, the halloysite has a nanotubular structure with a purity >96wt%, a diameter of 30-80nm, and a length of 1 μm.

Preferably, the aluminate cement is CA80 cement.

Preferably, the main component of the silica powder is spherical silica, with a purity of >99wt% and a fineness of 10 to 120nm.

Preferably, the quick-drying agent is lithium sulfate, lithium carbonate or a combination of the two.

Preferably, the anti-cracking agent is polypropylene fiber, with a length of 6 mm and an aspect ratio of 5 to 10.

Preferably, the water-reducing agent is a polycarboxylic acid-type water-reducing agent with a concentration of 50 wt%.

Preferably, the defoaming agent is a silicone defoaming agent.

Preferably, the particle size of the artificial porcelain sand is between 30 and 120 mesh, its alumina content is above 70wt%, and Fe ₂ O ₃ <2wt%.

Preferably, the preparation method of the artificial porcelain sand is as follows:

Bauxite, washed kaolin, quartz powder and dispersant are ball milled and mixed, then spray-dried into balls;

Plasticizer is added, dry-pressed into bricks, dried and sintered, cooled and then crushed and screened to obtain the artificial porcelain sand.

Preferably, the mass ratio of bauxite, washed kaolin and quartz powder is 40-70:20-30:5-15.

Preferably, the dispersant is sodium hexametaphosphate, polyacrylic acid or sodium tripolyphosphate, preferably sodium hexametaphosphate, and its dosage is 0.3-0.4wt based on the total mass of bauxite, washed kaolin and quartz powder. %.

Preferably, the particle size after spray drying into balls is 0.2 to 0.5 mm.

Preferably, the plasticizer is polyvinyl alcohol or carboxymethyl cellulose, and the dosage is 0.2 to 0.3 wt%.

Preferably, the dry-pressed bricks are dry-pressed into bricks under a pressure of 100-130 MPa.

Preferably, the drying is performed at 110-120°C for 20h-40h.

Preferably, the alumina content in the bauxite is 40 to 70 wt%, and the iron is removed after adding water and grinding to control the iron content below 2 wt%.

Preferably, the sintering temperature is 1600-1800°C, 10h-20h.

The preparation method of the cement adhesive, the method is: premix aluminate cement, artificial porcelain sand, anti-cracking agent, halloysite and silica powder to obtain a premix, and then add Add water-reducing agent, quick-drying agent and defoaming agent, then add water and stir for 6-8 minutes until evenly stirred to obtain the cement adhesive.

The application of the cement adhesive in the rapid test of the strength of porcelain insulators and porcelain parts is as follows: pour the cement adhesive into the porcelain parts, leave it for 3-4h, and dry it at 100-120°C for 18-20h. , ready for testing.

Preferably, the 1d compressive strength of the cement adhesive is above 100MPa, and the flexural strength is above 15MPa.

The present invention also provides the application of the cement adhesive in UHV large-tonnage disc-shaped suspended porcelain insulators. Among them, UHV is divided into UHV AC and UHV DC. UHV AC refers to voltages of 1000kV and above. UHV DC refers to voltages of ±800kV and above. Large tonnage refers to insulators with rated tensile strength of 420KN and above.

During the hydration reaction process of the aluminate cement of the present invention, the aluminate cement produces hydration products (such as CAH ₁₀ , C ₂ AH ₈ and C ₃ AH ₆ ). These hydration products are interlaced with each other and wrap the particles, making the casting The material has high strength. During the curing process, the hydration products of aluminate cement transform from CAH ₁₀ and C ₂ AH ₈ to C ₃ AH _6. This process is accompanied by volume shrinkage and increased porosity, resulting in a reduction in material bonding strength. The addition of halloysite, because its crystal composition is a monoclinic water-bearing layered structure silicate mineral, and its crystal structure is similar to kaolinite, is similar to the cement hydration products CAH ₁₀ , C ₂ AH ₈ and C ₃ AH ₆ and other materials have good compatibility. In addition, its unique nanotubular structure and AH ₃ gel, an important hydration product of aluminate cement, fill the pores between the crystal skeletons to form a denser structure. This is exactly how The synergistic effect gives the cement adhesive its good early strength and high strength properties.

Compared with the prior art, the beneficial effects of the present invention are:

Aluminate cement is used to replace Portland cement, and the incorporation of halloysite is used. Different from the traditional natural curing system, the baking process is used to make the strength of the cement adhesive reach more than 100MPa in 1 day; the use of nanostructured Halloysite is a reinforcing material that greatly improves the flexural strength of cement adhesives, while the use of concrete quick-drying agents greatly reduces the curing time of cement adhesives. The technical solution of the present invention is simple and the construction operation is convenient. The strength of the cement adhesive can be made above 100MPa within 1 day, which greatly shortens the testing period for the strength of porcelain parts from the original testing period of more than 7 days to less than 1 day, greatly improving the Product production cycle and efficiency.

Description of the drawings

Figure 1 is an SEM image of synthetic artificial porcelain sand. It can be seen from the figure that the prepared artificial porcelain sand has a dense structure, small porosity, and a size of 15 to 20 μm. This structure gives the cement adhesive high compressive strength. and flexural strength.

Figure 2 is an SEM image of spherical silica powder. It can be seen from the picture that the shape of silica powder is spherical, with a size of 10 to 120nm. This structure makes the adhesive have good flow properties.

Figure 3 is an SEM image of halloysite. From the image, you can clearly see its nanotubular structure, with a diameter of 80nm and a length of 1μm. Such nanostructures help improve the adhesive's flexural strength.

Figure 4 is a cross-sectional view of the cement adhesive after baking. It can be seen from the figure that the synthetic cement adhesive has high density, evenly distributed aggregates, and almost no pores.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with examples. It should be understood that the specific embodiments described here are only used to explain the present invention and are not intended to limit the present invention.

The invention provides a cement adhesive for rapid strength testing of porcelain insulators. The cement adhesive comprises the following components by weight percentage: 40-60wt% of aluminate cement, 15-50wt% of artificial porcelain sand, 2-5wt% of halloysite and 1-5wt% of silicon micropowder; 0.1-0.3wt% of polypropylene fiber as an anti-cracking agent and 0.1-0.3wt% of polycarboxylic acid as a water reducing agent in a total weight; 0.1-0.5wt% of a quick-drying agent; and 0.1-0.3wt% of a defoaming agent.

According to the above weight percentage, premix aluminate cement, artificial porcelain sand, anti-cracking agent, halloysite and silica powder for 8 to 10 minutes to obtain a premix, and then add water reducing agent, Quick-drying agent and defoaming agent, then add water and stir for 5 minutes. The amount of water added is such that the water-cement ratio is 0.15 to obtain the cement adhesive. Pour the cement adhesive into the porcelain piece and leave it for 4 hours. At 100 After drying at -120℃ for 18-20h, it can be used for testing.

Specifically, aluminate cement uses CA80 cement, and the aggregate is synthetic artificial porcelain sand. It is different from the river sand and quartz sand currently used. Its main components are alumina and mullite, and its performance is better than river sand and quartz sand. The sand is more stable, has excellent toughness, and does not have the potential hazards of alkali aggregate reactions, greatly improving the long-term life and safety of cement adhesives. The nanostructured halloysite used greatly improves the flexural strength of cement adhesives. In addition, high-purity spherical silica powder is used, which has small addition amount, good fluidity and high density, which contributes to the long-term stability of cement adhesives and even porcelain insulators. performance and operational safety. In addition, polypropylene fiber is used as anti-cracking agent and high-efficiency water-reducing agent, and a certain amount of defoaming agent is added to reduce the generation of large bubbles. To sum up, the cement adhesive prepared by the present invention has excellent performance and short curing time, which is helpful for rapid detection of the strength of porcelain insulators and greatly improves production efficiency.

The preparation method of artificial porcelain sand of the present invention is as follows:

Use bauxite as raw material, add water to grind it, remove iron, control the iron content below 2%, add washed kaolin, quartz powder, dispersant, etc. for ball milling and wet mixing. Bauxite: kaolin: quartz powder = 40 to 70 wt%: 20 to 30 wt%: 5 to 15 wt%. Dispersants generally use sodium hexametaphosphate, polyacrylic acid, sodium tripolyphosphate, etc., mainly to make the entire system materials more uniform after mixing. The present invention uses sodium hexametaphosphate, and its dosage is bauxite, washed kaolin, and quartz powder. The total mass is 0.3~0.4%. Wet-mix the raw materials for more than 20 hours to make the entire slurry evenly mixed, then spray-dry them into balls with a particle size of 0.2 to 0.5 mm. Add a certain amount of plasticizer, such as polyvinyl alcohol or carboxymethyl cellulose 0.2 to 0.3 %, dry-press into bricks under a pressure of 100MPa, then dry at 110°C for more than 20 hours, and then placed in a tunnel kiln for sintering according to a certain sintering process. The maximum sintering temperature is 1600°C for more than 10 hours. After cooling, the bricks are placed in a crusher for crushing and then screened to select particles with a particle size of 30 to 70 mesh as the required artificial porcelain sand.

Specific examples and comparative examples of the present invention are shown in Table 1 below:

Table 1

Note: 1. Portland cement adhesive is maintained according to natural methods.

2. The water-cement ratio during the experiment is the same.

The experimental results of specific embodiments of the present invention and comparative examples are shown in Table 2 below:

Table 2

Example 1

This embodiment provides a cement adhesive for rapid testing of the strength of porcelain insulators: 60wt% aluminate cement, 30wt% artificial porcelain sand, 5wt% halloysite, and 5wt% high-purity silica powder. In addition to the total weight of 0.1wt% polypropylene fiber as anti-cracking agent, add 0.1wt% water reducing agent; 0.1wt% quick-drying agent; 0.2wt% defoaming agent. According to the above percentage content, first premix aluminate cement with artificial porcelain sand, anti-cracking agent, halloysite and high-purity silica powder to obtain a premix, and then add water-reducing agent, Quick-drying agent and defoaming agent, then add water and stir for 5 minutes to obtain the cement adhesive. Pour the cement adhesive into the porcelain piece, leave it for 4 hours, and then bake it at 110°C for 20 hours. After demoulding, maintain it to the specified Test its performance after age.

The measured compressive strength of 1d cement adhesive is 103.5MPa, and the flexural strength is 16.5MPa. The compressive strength of 11d cement adhesive is 112.0MPa, and the flexural strength is 21.6MPa. The dry shrinkage rate of 11d is 0.04%. The 11d elastic modulus is 42.1GPa. The water absorption rate of the adhesive is 3.8%, the pressure steam expansion rate is 0.04%, and the fluidity is greater than 300mm. It is self-leveling and meets the current specifications for cement adhesives.

Example 2

This embodiment provides a cement adhesive for quick strength testing of porcelain insulators: 50wt% aluminate cement, 45wt% artificial porcelain sand, 2wt% halloysite, and 3wt% high-purity silica powder. In addition, 0.2wt% polypropylene fiber of the total weight is used as an anti-cracking agent, 0.2wt% water-reducing agent; 0.2wt% quick-drying agent; 0.2wt% defoaming agent. According to the above percentage content, first premix aluminate cement with artificial porcelain sand, anti-cracking agent, halloysite and high-purity silica powder to obtain a premix, and then add water-reducing agent, Quick-drying agent and defoaming agent, then add water and stir for 5 minutes to obtain the cement adhesive. Pour the cement adhesive into the porcelain piece, leave it for 4 hours, and then bake it at 110°C for 20 hours. After demoulding, maintain it to the specified Test its performance after age.

The measured compressive strength of 1d cement adhesive is 106.5MPa, and the flexural strength is 17.4MPa. The compressive strength of 11d cement adhesive is 115.5MPa, and the flexural strength is 22.8MPa. The dry shrinkage rate of 11d is 0.04%. The 11d elastic modulus is 45.4GPa. The water absorption rate of the adhesive is 3.5%, the pressure steam expansion rate is 0.05%, and the fluidity is 260mm, which meets the current specifications for cement adhesives.

Example 3

This embodiment provides a cement adhesive for rapid strength testing of porcelain insulators: 45wt% aluminate cement, 49wt% artificial porcelain sand, 2wt% halloysite, and 4wt% high-purity silica powder. In addition to the total weight of 0.1wt% polypropylene fiber as anti-cracking agent, add 0.1wt% water reducing agent; 0.1wt% quick-drying agent; 0.2wt% defoaming agent. According to the above percentage content, first premix aluminate cement with artificial porcelain sand, anti-cracking agent, halloysite and high-purity silica powder to obtain a premix, and then add water-reducing agent, Quick-drying agent and defoaming agent, then add water and stir for 5 minutes to obtain the cement adhesive. Pour the cement adhesive into the porcelain piece, leave it for 4 hours, and then bake it at 110°C for 20 hours. After demoulding, maintain it to the specified Test its performance after age.

The measured compressive strength of 1d cement adhesive is 109.2MPa, and the flexural strength is 20.6MPa. The compressive strength of 11d cement adhesive is 123.7MPa, and the flexural strength is 24.3MPa. The dry shrinkage rate of 11d is 0.05%. The 11d elastic modulus is 47.8GPa. The water absorption rate of the adhesive is 3.5%, the pressure steam expansion rate is 0.06%, and the fluidity is 270mm, which meets the current specifications for cement adhesives.

Example 4

This embodiment provides a cement adhesive for quick strength testing of porcelain insulators: 40wt% aluminate cement, 53wt% artificial porcelain sand, 2wt% halloysite, and 5wt% high-purity silica powder. In addition, 0.1wt% polypropylene fiber of the total weight is used as an anti-cracking agent, and 0.3wt% water-reducing agent; 0.3wt% quick-drying agent; and 0.3wt% defoaming agent are added. According to the above percentage content, first premix aluminate cement with artificial porcelain sand, anti-cracking agent, halloysite and high-purity silica powder to obtain a premix, and then add water-reducing agent, Quick-drying agent and defoaming agent, then add water and stir for 5 minutes to obtain the cement adhesive. Pour the cement adhesive into the porcelain piece, leave it for 4 hours, and then bake it at 110°C for 20 hours. After demoulding, maintain it to the specified Test its performance after age.

The measured compressive strength of 1d cement adhesive is 112.4MPa, and the flexural strength is 22.5MPa. The compressive strength of 11d cement adhesive is 125.6MPa, and the flexural strength is 25.8MPa. The dry shrinkage rate of 11d is 0.05%. The 11d elastic modulus is 49.6GPa. The water absorption rate of the cement is 3.2%, the steam expansion rate is 0.05%, and the fluidity is 280mm, which meets the current specifications for cement cement.

Comparative example 1

The main formula and process of this comparative example are the same as those of Example 1, except that it uses 60wt% Portland cement, 92% ordinary silica powder, and no halloysite is added.

The measured compressive strength of 1d cement adhesive is 35.2MPa, and the flexural strength is 4.5MPa. The compressive strength of 11d cement adhesive is 90.4MPa, and the flexural strength is 7.8MPa. The dry shrinkage rate of 11d is 0.09%. The 11d elastic modulus is 36.5GPa. The water absorption rate of the adhesive is 5.5%, the steam expansion rate is 0.08%, and the fluidity is 210 mm. The compressive strength and flexural strength in 1 day are obviously lower than those in Example 1, and cannot be used to test the strength of porcelain parts.

Comparative example 2

The main formula and process of this comparative example are the same as those of Example 1. The difference is that the aggregate is ordinary river sand, ordinary silica powder with a content of 92%, and no halloysite is added.

The measured compressive strength of 1d cement adhesive is 80.4MPa, and the flexural strength is 6.8MPa. The compressive strength of 11d cement adhesive is 97.8MPa, and the flexural strength is 9.6MPa. The dry shrinkage rate of 11d is 0.07%. The 11d elastic modulus is 32.8GPa. The water absorption rate of the adhesive is 5.8%, the steam expansion rate is 0.09%, and the fluidity is 220mm. The compressive strength and flexural strength in 1d are obviously lower than those in Example 1, especially the compressive strength is less than 90MPa, so it cannot Testing the strength of porcelain parts.

Comparative example 3

The main formula and process of this comparative example are the same as those of Example 1, except that ordinary silica powder with a content of 92% is used and no halloysite is added.

The measured compressive strength of 1d cement adhesive is 92.6MPa, and the flexural strength is 8.5MPa. The compressive strength of 11d cement adhesive is 101.4MPa, and the flexural strength is 12.8MPa. The dry shrinkage rate of 11d is 0.06%. The 11d elastic modulus is 40.9GPa. The water absorption rate of the adhesive is 4.0%, the autoclaved expansion rate is 0.06%, the fluidity is 200mm, and the compressive strength and flexural strength in 1d are lower than those in Example 1. Although its strength can meet the requirements of porcelain parts testing, Its fluidity is small, resulting in high viscosity and affecting its actual use.

Comparative example 4

The main formula and process of this comparative example are the same as those of Example 1, except that halloysite is not added and the amount of high-purity silica powder is 10 wt%.

The measured compressive strength of 1d cement adhesive is 85.2MPa, and the flexural strength is 10.5MPa. The compressive strength of 11d cement adhesive is 91.7MPa, and the flexural strength is 13.4MPa. The dry shrinkage rate of 11d is 0.08%. The 11d elastic modulus is 39.2GPa. The water absorption rate of the adhesive is 4.2%, the steam expansion rate is 0.07%, the fluidity is greater than 300mm, and it is self-leveling. The compressive strength and flexural strength of 11d are lower than that of Example 1, and the dry shrinkage and water absorption rate are both greater than that of Example 1. Its comprehensive performance is lower than that of Example 1.

The above-mentioned embodiments are only examples for clear explanation and are not intended to limit the implementation. For those of ordinary skill in the art, other changes or changes in different forms can be made based on the above description. It is not necessary and impossible to exhaustively enumerate all the implementation methods. Therefore, the obvious changes or changes are derived. are still within the protection scope of the present invention.

Claims (10)

1. A cement adhesive for rapid testing of the strength of porcelain insulators, characterized in that the cement adhesive includes the following components in weight percentage: 40 to 60 wt% aluminate cement, 30 to 50 wt% artificial porcelain Sand, 2-5wt% halloysite, 1-5wt% silica powder, the cement adhesive also includes external anti-cracking agent, water-reducing agent, quick-drying agent and defoaming agent, the anti-cracking agent , water reducing agent, quick-drying agent and defoaming agent are added in amounts of 0.1~0.3wt%, 0.1~0.3wt%, 0.1~0.5wt% and 0.1~0.3wt% respectively. 2. The cement adhesive according to claim 1, wherein the halloysite is a nanotube structure, Diameter is 30-80nm. 3. The cement adhesive according to claim 1, characterized in that the purity of the halloysite is >96wt%. 4. The cement adhesive according to claim 1, characterized in that the aluminate cement is CA80 cement. 5. The cement adhesive according to claim 1, characterized in that the main component of the silica powder is spherical silica, with a purity of >99wt% and a fineness of 10-120nm. 6. The cement adhesive according to claim 1, characterized in that the quick-drying agent is lithium sulfate, lithium carbonate or a combination of the two. 7. The cement adhesive according to claim 1, characterized in that the particle size of the artificial porcelain sand is between 30 and 120 mesh, its alumina content is above 70wt%, and Fe ₂ O ₃ <2wt%. 8. The preparation method of cement adhesive according to any one of claims 1 to 7, characterized in that the method is: pre-preparing aluminate cement, artificial porcelain sand, anti-cracking agent, halloysite and silica powder. Mix to obtain a premix, then add a water-reducing agent, a quick-drying agent and a defoaming agent to the premix, then add water and stir evenly to obtain the cement adhesive. 9. The application of the cement adhesive obtained by the cement adhesive preparation method as claimed in claim 8 in the rapid test of the strength of porcelain insulators and porcelain parts, characterized in that the application is: pouring the cement adhesive into the porcelain insulator. Place it in the mold for 3-4 hours, dry it at 100-120℃ for 18-20 hours, and then it can be used for testing. 10. The application according to claim 9, characterized in that the 1d compressive strength of the cement adhesive is above 100 MPa, and the flexural strength is above 15 MPa.