CN114453555A - A kind of preparation technology of high temperature resistant coated sand - Google Patents

Abstract

The invention relates to the technical field of coated sand processing, in particular to a process for preparing high temperature resistant coated sand, comprising the following steps: (1) surface treatment, (2) surface filling of raw sand, (3) configuration of a film-forming liquid, (4) ) surface adsorption of raw sand, (5) raw sand resin coating, the present invention utilizes the modification of the sand body surface and the coating of phenolic resin and silicone rubber to significantly improve the high temperature stability of the coated sand, so that the coated sand can be prepared The castings have better high temperature resistance, and the performance is more stable under complex high temperature conditions.

Description

A kind of preparation technology of high temperature resistant coated sand

technical field

The invention relates to the technical field of coated sand processing, in particular to a process for preparing high temperature resistant coated sand.

Background technique

Coated sand refers to molding sand or core sand whose surface is covered with a solid resin film before molding. Due to the advantages of high strength, low gas generation, high dimensional accuracy of production castings, smooth surface, and easy preservation, coated sand has been widely used in recent years. However, the existing coated sand cannot meet the needs of existing production. In the prior art, molybdenum-modified high-ortho phenolic resins are mostly used as binders, together with dehydrating agents, curing agents and lubricants. . However, in the practical application of high temperature resistant coated sand, due to the lack of targeted modification of the original sand surface, the high temperature stability in actual use is poor.

SUMMARY OF THE INVENTION

In order to solve the problems existing in the prior art, the present invention provides a process for preparing high temperature resistant coated sand to improve the strength of the coated sand and improve its performance. The specific technical scheme is as follows:

A process for preparing high temperature resistant coated sand, comprising the following steps:

(1) Surface treatment

First put the original sand into the sand mixer, heat it to 160-170℃, keep the temperature for 20-30min, spread the original sand to a thickness of 1-2cm, spray dilute sulfuric acid on the surface of the original sand, and spread it out for 10-13min; heat the temperature To 80-100 ℃, preheat for 10-15 minutes, continue to increase the temperature to 180-190 ℃, spread the original sand again and spray with dilute sulfuric acid, rinse the original sand with clean water until the pH is neutral, at 100-110 ℃ bake for 1-2h;

(2) Surface filling of original sand

Cool the raw sand obtained in the previous step to 25-28°C, add aniline methyl triethoxysilane, stir at 200-300r/min for 40-43min at 30-35°C, ultrasonically treat it for 10-15min, and seal it. Place for 30-50min;

(3) Configure the film-forming liquid

The silicone rubber and tetrahydrofuran are mixed uniformly according to the mass ratio of 1:15-20, and calcium sulfate whiskers of 2-4% by mass of the silicone rubber are added and mixed for 50-60min;

(4) Adsorption on the surface of raw sand

Mix the above-mentioned film liquid and the raw sand treated in step (2) according to the mass ratio of 1:58-65, add N-phenyl-γ-aminopropyltrimethoxysilane with a mass of 4-7% silicone rubber, and stir for 48- 55min, heated to 140-150℃ to cure;

(5) Original sand resin coating

In parts by mass, 1-3 parts of boron phenolic resin, 4-8 parts of molybdenum phenolic resin, 2-5 parts of titanium phenolic resin, and 200-300 parts of acetone are mixed and heated to dissolve to obtain a phenolic resin coating liquid, and the phenolic resin is coated. The film liquid and the solidified product in the previous step are mixed at 1000-2000r/min and stirred for 30-50min, the temperature is raised to 180-200°C, and then cooled and pulverized.

Further, in step (1), each spraying amount of the dilute sulfuric acid is 3-5% of the quality of the original sand.

Further, in step (1), the concentration of the dilute sulfuric acid is 0.03-0.07mol/L.

Further, in step (1), the temperature of the dilute sulfuric acid is 3-5°C.

Further, in step (1), the particle size of the original sand is 100-200 mesh.

Further, in step (2), the ultrasonic power is 800-900W.

Further, in step (5), the mass ratio of the phenolic resin coating liquid and the cured product is 1:15-18.

Compared with the prior art, the technical effect of the present invention is embodied in:

By treating the raw sand at high temperature and then spraying low-temperature dilute sulfuric acid, the invention utilizes the etching effect of the acid and the expansion and contraction effect of the sand body under the obvious temperature difference to make a large number of scratches on the surface of the sand body, improve the roughness of the surface of the raw sand, and make the sand body surface rough. Raw sand has a larger surface area. In the surface treatment, the sand body has a larger contact surface with silicone rubber, boron phenolic resin, molybdenum phenolic resin and titanium phenolic resin. In the invention, the sand body is fully mixed and adsorbed with aniline methyl triethoxysilane, and in the treatment of the silicone rubber coating liquid, the concentrated adhesion of the silicone rubber on the surface of the sand body is promoted and the curing of the silicone rubber is accelerated, and then the phenolic resin coating liquid is added. Further curing and mixing make the surface of the sand body covered with phenolic resin to obtain a complete coated sand. The modification of the surface of the sand body and the coating of phenolic resin and silicone rubber can significantly improve the high temperature stability of the coated sand and make the coated sand. The prepared casting has better high temperature resistance effect, and the performance is more stable under complex high temperature conditions.

Detailed ways

The technical solutions of the present invention will be further limited below in conjunction with specific embodiments, but the scope of protection is not limited to the description. The raw sand used in the following examples is all quartz sand.

Example 1

A process for preparing high temperature resistant coated sand, comprising the following steps:

(1) Surface treatment

First put the raw sand into the sand mixer, heat it to 160℃, keep the temperature for 20min, pour the raw sand into the bulk material yard and spread it to a thickness of 1cm, quickly spray dilute sulfuric acid on the surface of the raw sand, and spread it out for 10min; collect the raw sand and put it in In the sand mixer, heat the temperature to 80 °C, preheat for 10 minutes, continue to increase the temperature to 180 °C, pour the raw sand into the bulk material yard again, spread it out and spray with dilute sulfuric acid, wait for the raw sand to cool down to room temperature, use water Rinse the original sand until the pH is neutral, and bake at 100°C for 1h;

Each spraying amount of the dilute sulfuric acid is 3% of the mass of the original sand, the concentration of the dilute sulfuric acid is 0.03 mol/L, and the temperature of the dilute sulfuric acid is 3°C; the particle size of the original sand is 100 mesh;

(2) Surface filling of original sand

Cool the raw sand obtained in the previous step to 25°C, add anilinomethyltriethoxysilane, stir at 200r/min for 40min at 30°C, ultrasonically treat for 10min, and place in a sealed place for 30min; the ultrasonic power is 800W;

(3) Configure the film-forming liquid

The silicone rubber and tetrahydrofuran are mixed uniformly according to the mass ratio of 1:15, and the calcium sulfate whiskers of 2% by mass of the silicone rubber are added and mixed for 50 minutes;

(4) Surface adsorption of raw sand

Mix the above film liquid and the raw sand treated in step (2) according to the mass ratio of 1:58, add N-phenyl-γ-aminopropyltrimethoxysilane with 4% by mass of silicone rubber, stir for 48 minutes, and heat to 140 ° C can be cured;

(5) Original sand resin coating

In parts by mass, 1 part of boron phenolic resin, 4 parts of molybdenum phenolic resin, 2 parts of titanium phenolic resin, and 200 parts of acetone are mixed and heated to dissolve to obtain a phenolic resin coating liquid, and the phenolic resin coating liquid is mixed with the previous step. The cured product was mixed at 1000 r/min and stirred for 30 min, the temperature was raised to 180° C., cooled and pulverized; the mass ratio of the phenolic resin coating liquid and the cured product was 1:15.

Example 2

A process for preparing high temperature resistant coated sand, comprising the following steps:

(1) Surface treatment

First put the raw sand into the sand mixer, heat it to 170°C, keep the temperature for 30min, spread the raw sand to a thickness of 2cm, spray dilute sulfuric acid on the surface of the raw sand, and spread it out for 13min; heat the temperature to 100°C, preheat for 15min, Continue to raise the temperature to 190°C, spread the original sand again and spray with dilute sulfuric acid, rinse the original sand with clean water until the pH is neutral, and bake at 110°C for 2 hours;

Each spraying amount of the dilute sulfuric acid is 5% of the quality of the original sand, the concentration of the dilute sulfuric acid is 0.07mol/L, and the temperature of the dilute sulfuric acid is 5°C; the particle size of the original sand is 200 mesh;

(2) Surface filling of original sand

Cool the raw sand obtained in the previous step to 28°C, add anilinomethyltriethoxysilane, stir at 300r/min for 43min at 35°C, ultrasonically treat for 15min, and place in a sealed place for 50min; the ultrasonic power is 900W;

(3) Configure the film-forming liquid

The silicone rubber and tetrahydrofuran were mixed uniformly according to the mass ratio of 1:20, and the calcium sulfate whiskers of 4% by mass of the silicone rubber were added and stirred for 60 min;

(4) Adsorption on the surface of raw sand

Mix the above-mentioned film liquid and the raw sand treated in step (2) according to the mass ratio of 1:65, add N-phenyl-γ-aminopropyltrimethoxysilane with 7% by mass of silicone rubber, stir for 55 minutes, and heat to 150 ° C can be cured;

(5) Original sand resin coating

In parts by mass, 3 parts of boron phenolic resin, 8 parts of molybdenum phenolic resin, 5 parts of titanium phenolic resin, and 300 parts of acetone are mixed and heated to dissolve to obtain a phenolic resin coating liquid, and the phenolic resin coating liquid and the previous step are mixed and heated. The cured product was mixed at 2000 r/min and stirred for 50 min, the temperature was raised to 200° C., cooled and pulverized; the mass ratio of the phenolic resin coating liquid and the cured product was 1:18.

Example 3

A process for preparing high temperature resistant coated sand, comprising the following steps:

(1) Surface treatment

First put the original sand into the sand mixer, heat it to 165℃, keep the temperature for 24min, spread the original sand to a thickness of 1cm, spray dilute sulfuric acid on the surface of the original sand, and spread it out for 13min; heat the temperature to 100℃, preheat for 10min, Continue to raise the temperature to 190°C, spread out the original sand again and spray with dilute sulfuric acid, rinse the original sand with clean water until the pH is neutral, and bake at 110°C for 1 hour;

Each spraying amount of the dilute sulfuric acid is 5% of the mass of the original sand, the concentration of the dilute sulfuric acid is 0.03 mol/L, and the temperature of the dilute sulfuric acid is 5°C; the particle size of the original sand is 100 mesh;

(2) Surface filling of original sand

Cool the raw sand obtained in the previous step to 28°C, add aniline methyl triethoxysilane, stir at 300r/min for 40min at 30°C, ultrasonically treat for 15min, and place in a sealed place for 50min; the ultrasonic power is 800W;

(3) Configure the film-forming liquid

The silicone rubber and tetrahydrofuran were mixed uniformly according to the mass ratio of 1:20, and the calcium sulfate whiskers of 2% by mass of the silicone rubber were added and stirred for 60 min;

(4) Adsorption on the surface of raw sand

Mix the above-mentioned film liquid and the raw sand treated in step (2) according to the mass ratio of 1:65, add N-phenyl-γ-aminopropyltrimethoxysilane with 4% by mass of silicone rubber, stir for 55 minutes, and heat to 140 ° C can be cured;

(5) Original sand resin coating

In parts by mass, 3 parts of boron phenolic resin, 8 parts of molybdenum phenolic resin, 2 parts of titanium phenolic resin, 200 parts of acetone are mixed and heated to dissolve to obtain a phenolic resin coating liquid, and the phenolic resin coating liquid and the previous step are mixed and heated. The cured product was mixed at 1000 r/min and stirred for 50 min, the temperature was raised to 200° C., cooled and pulverized; the mass ratio of the phenolic resin coating liquid and the cured product was 1:15.

Contrast ratio settings:

Test example

Coated sands were made according to Examples 1-3 and Comparative Examples 1-4 respectively, and the coated sands were made into coated castings, and their performance parameters were tested. , and check its performance parameters again.

It can be seen from the table that the tensile strength of the coated castings of Examples 1-3 according to the method of the present invention is significantly higher than that of Comparative Examples 1-3. It can be seen that the coated sand of the present application has brought good structural improvement and improved the coating. Properties of Membrane Castings.

Performance parameters after aging:

It can be seen from the table that after aging, the performance of Examples 1-3 is basically equivalent to the performance parameters before aging, and the performance parameters of Comparative Examples 1-4 drop significantly, only about 85% of those before aging. It can be seen that the film of the present invention is The film-coated castings produced have excellent stability at high temperature and have good anti-aging effect.

Claims (7)

1. a high temperature resistant coated sand preparation technology, is characterized in that, comprises the steps: (1) Surface treatment First put the original sand into the sand mixer, heat it to 160-170℃, keep the temperature for 20-30min, spread the original sand to a thickness of 1-2cm, spray dilute sulfuric acid on the surface of the original sand, and spread it out for 10-13min; heat the temperature To 80-100 ℃, preheat for 10-15 minutes, continue to increase the temperature to 180-190 ℃, spread the original sand again and spray with dilute sulfuric acid, rinse the original sand with clean water until the pH is neutral, at 100-110 ℃ bake for 1-2h; (2) Surface filling of original sand Cool the raw sand obtained in the previous step to 25-28°C, add aniline methyl triethoxysilane, stir at 200-300r/min for 40-43min at 30-35°C, ultrasonically treat it for 10-15min, and seal it. Place for 30-50min; (3) Configure the film-forming liquid The silicone rubber and tetrahydrofuran are mixed uniformly according to the mass ratio of 1:15-20, and calcium sulfate whiskers of 2-4% by mass of the silicone rubber are added and mixed for 50-60min; (4) Adsorption on the surface of raw sand Mix the above-mentioned film liquid and the raw sand treated in step (2) according to the mass ratio of 1:58-65, add N-phenyl-γ-aminopropyltrimethoxysilane with a mass of 4-7% silicone rubber, and stir for 48- 55min, heated to 140-150℃ to cure; (5) Original sand resin coating In parts by mass, 1-3 parts of boron phenolic resin, 4-8 parts of molybdenum phenolic resin, 2-5 parts of titanium phenolic resin, and 200-300 parts of acetone are mixed and heated to dissolve to obtain a phenolic resin coating liquid, and the phenolic resin is coated. The film liquid and the solidified product in the previous step are mixed at 1000-2000r/min and stirred for 30-50min, the temperature is raised to 180-200°C, and then cooled and pulverized. 2 . The high temperature resistant coated sand preparation process according to claim 1 , wherein, in step (1), the amount of dilute sulfuric acid sprayed each time is 3-5% of the quality of the original sand. 3 . 3 . The process for preparing high temperature resistant coated sand according to claim 1 , wherein, in step (1), the concentration of the dilute sulfuric acid is 0.03-0.07 mol/L. 4 . 4 . The process for preparing high temperature resistant coated sand according to claim 1 , wherein, in step (1), the temperature of the dilute sulfuric acid is 3-5° C. 5 . 5 . The high temperature resistant coated sand preparation process according to claim 1 , wherein in step (1), the particle size of the raw sand is 100-200 mesh. 6 . 6 . The process for preparing high temperature resistant coated sand according to claim 1 , wherein in step (2), the ultrasonic power is 800-900W. 7 . 7 . The process for preparing high temperature resistant coated sand according to claim 1 , wherein in step (5), the mass ratio of the phenolic resin coating liquid and the cured product is 1:15-18. 8 .