Method for improving compressive strength of hollow glass microspheres based on heat treatment and quenching

Abstract

The application discloses a method for improving the compressive strength of hollow glass microspheres based on heat treatment and quenching. The hollow glass microspheres provided by the application are subjected to post-treatment by a physical method on the basis of the existing strength, so that the hollow glass microspheres with a larger particle size are broken, and thus the average particle size is reduced. In addition, the stress difference formed in the thin wall during the rapid cooling process makes the compressive strength of the hollow glass microspheres improved. The application overcomes the defects of the prior art and has the advantages of high implementability, obvious strengthening effect and the like.

Description

Technical Field

[0001] This invention relates to the field of hollow glass microsphere processing technology, specifically to a method for improving the compressive strength of hollow glass microspheres based on heat treatment and quenching. Background Technology

[0002] Hollow glass microspheres (HGMs) are a type of hollow, inorganic, non-metallic spherical material, mainly composed of SiO2 and Al2O3. They possess advantages such as low density, high strength, low thermal conductivity, good dispersibility, high stability, and good flowability. They also exhibit excellent properties including fire resistance, corrosion resistance, radiation protection, self-lubrication, low water and oil absorption, and sound and heat insulation. As fillers in composite materials such as fiberglass, artificial marble, and artificial agate, as well as in thermal insulation coatings, hollow glass microspheres are widely used in the petroleum industry, aerospace, new high-speed trains, automobiles, and ships. They reduce product weight, lower manufacturing costs, and improve sound and heat insulation, fire resistance, and electrical insulation properties, earning them the reputation of being a "space-age material" for the 21st century.

[0003] The main indicators of hollow glass microspheres include compressive strength, true density, floatability, flowability, and particle size. Among these, compressive strength is one of the most important indicators, playing a crucial role in applications such as automotive composites and thermal insulation coatings. The compressive strength of hollow glass microspheres mainly comes from their spherical structure and the inherent strength of the glass shell. Physical tempering is one of the main methods of glass strengthening. This involves heating the glass to near its softening temperature and then rapidly cooling it. The surface contracts sharply, creating compressive stress, while the interior cools more slowly, creating tensile stress. This stress difference increases the glass's strength.

[0004] Compared to imported hollow glass microspheres, domestically produced hollow glass microspheres have lower strength and poorer performance. Domestic research on improving the strength of hollow glass microspheres mainly focuses on refining the formulation and preparation process. Furthermore, research on post-processing of hollow glass microspheres tends to focus on coating the surface with metal ions, testing the enhancing effect of the metal-coated powder on electromagnetic shielding, and the impact of filling polymer materials on material properties. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a method for improving the compressive strength of hollow glass microspheres based on heat treatment and quenching. This method involves subjecting the hollow glass microspheres to high-temperature heat treatment, followed by immersing the high-temperature hollow glass microsphere powder in a quenching medium for cooling, thereby achieving the goal of improving the compressive strength of the hollow glass microspheres.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for improving the compressive strength of hollow glass microspheres based on heat treatment and quenching includes the following steps:

[0008] (1) High temperature heat treatment: The hollow glass microsphere powder is placed in a muffle furnace for high temperature heat treatment. When the muffle furnace reaches the set temperature, it is kept at the temperature.

[0009] (2) Quenching treatment: The powder after high-temperature heat treatment is placed in a quenching medium for cooling, and then filtered and dried.

[0010] Preferably, in step (1), the temperature of the high-temperature heat treatment is 500-600℃.

[0011] More preferably, the high-temperature heat treatment temperature can be selected from 500℃, 510℃, 520℃, 530℃, 540℃, 550℃, 560℃, 570℃, 580℃, 590℃, and 600℃.

[0012] Preferably, in step (1), the heating rate of the muffle furnace is 2.5-10℃ / min.

[0013] Further preferably, the heating rate of the muffle furnace can be selected as 2.5℃ / min, 5℃ / min, 7.5℃ / min, or 10℃ / min.

[0014] Preferably, in step (1), the heat preservation time is 30-40 minutes.

[0015] Preferably, in step (2), the quenching medium is pure water, quenching oil or salt solution.

[0016] Further preferably, potassium chloride solution is selected as the quenching medium.

[0017] Preferably, in step (2), during cooling, the mechanical stirring speed is 300-500 r / min, and the mechanical stirring time is 5-10 min.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The hollow glass microspheres provided by this invention, based on existing strength, undergo post-processing through physical methods to break larger-diameter hollow glass microspheres, thereby reducing the average particle size. In addition, the stress difference formed inside and outside the thin wall during rapid cooling increases the compressive strength of the hollow glass microspheres. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the process for processing hollow glass microsphere powder under different processing conditions;

[0021] Figure 2Electron micrographs of hollow glass microsphere powder under different processing conditions are shown. Figure 2 (a) is an electron microscope image of the hollow glass microspheres prepared in Example 1. Figure 2 (b) is an electron microscope image of the hollow glass microspheres prepared in Example 2. Figure 2 (c) is an electron microscope image of the hollow glass microspheres prepared in Example 3. Detailed Implementation

[0022] The present invention will be further described in detail below through specific preferred embodiments, but the present invention is not limited to the following embodiments.

[0023] It should be noted that, unless otherwise specified, all chemical reagents involved in this invention were purchased through commercial channels.

[0024] The hollow glass microspheres used in this invention are of model GS46, and the product has a compressive strength of 30MPa.

[0025] Example 1

[0026] A method for improving the compressive strength of hollow glass microspheres based on heat treatment and quenching includes the following steps:

[0027] (1) Weigh 25g of hollow glass microsphere powder and put it into a 100mL ceramic crucible. Heat it to 580℃ in a muffle furnace at a heating rate of 5℃ / min and keep it at that temperature for 30min.

[0028] (2) Take out the powder after high temperature heat treatment and quickly put it into 300mL of pure water to cool it. Stir it mechanically for 5min at a speed of 300r / min. Then, vacuum filter the hollow glass microspheres and dry them in an oven at 105℃.

[0029] Compressive strength test: The compressive strength of the samples was measured using an Autopore IV 9500 mercury porosimeter. A certain pressurization rate was set during the test. The relationship between volume breakage rate and compressive strength was obtained based on the pressure-cumulative mercury ingress curve. The pressure corresponding to a volume breakage rate of 25% was used as the standard for measuring the compressive strength of the powder. At a heating rate of 5℃ / min, the highest compressive strength of the powder at 580℃ was 46.3MPa, which was 54.3% higher than the compressive strength of the original powder sample.

[0030] Example 2

[0031] A method for improving the compressive strength of hollow glass microspheres based on heat treatment and quenching includes the following steps:

[0032] (1) Weigh 25g of hollow glass microsphere powder and put it into a 100mL ceramic crucible. Heat it to 580℃ in a muffle furnace at a heating rate of 5℃ / min and keep it at that temperature for 30min.

[0033] (2) Take out the powder after high temperature heat treatment and quickly put it into 300mL potassium chloride solution to cool. Stir mechanically for 5min at a speed of 300r / min. Then, vacuum filter the hollow glass microspheres and dry them in an oven at 105℃.

[0034] Compressive strength test: The compressive strength of the samples was measured using an Autopore IV 9500 mercury porosimeter. A certain pressurization rate was set during the test. The relationship between volume breakage rate and compressive strength was obtained based on the pressure-cumulative mercury ingress curve. The pressure corresponding to a volume breakage rate of 25% was used as the standard for measuring the compressive strength of the powder. At a heating rate of 5℃ / min, the highest compressive strength of the powder at 580℃ was 56.1MPa, which is 87% higher than the compressive strength of the original powder sample.

[0035] Example 3

[0036] A method for improving the compressive strength of hollow glass microspheres based on heat treatment and quenching includes the following steps:

[0037] (1) Weigh 25g of hollow glass microsphere powder and put it into a 100mL ceramic crucible. Heat it to 580℃ in a muffle furnace at a heating rate of 5℃ / min and keep it at that temperature for 30min.

[0038] (2) Take out the powder after high temperature heat treatment and quickly put it into 300mL of quenching oil to cool it. Stir it mechanically for 5 minutes at a speed of 300r / min. Then, vacuum filter the hollow glass microspheres and dry them in an oven at 105℃.

[0039] Compressive strength test: The compressive strength of the sample was measured using an Autopore IV 9500 mercury porosimeter. A certain pressurization rate was set during the test. The relationship between volume breakage rate and compressive strength was obtained based on the pressure-cumulative mercury ingress curve. The pressure corresponding to a volume breakage rate of 25% was used as the standard for measuring the compressive strength of the powder. At a heating rate of 5℃ / min, the highest compressive strength of the powder at 580℃ was 62.8MPa, which was about 1 times higher than the compressive strength of the original powder sample.

[0040] This invention also systematically studied the compressive strength of hollow glass microsphere powder under different processing techniques, as detailed below:

[0041] The compressive strength of hollow glass microspheres quenched in pure water at different heating rates / heat treatment temperatures is shown in Table 1:

[0042] Table 1

[0043]

[0044] The compressive strength of hollow glass microspheres quenched with potassium chloride at different heating rates / heat treatment temperatures is shown in Table 2:

[0045] Table 2

[0046]

[0047]

[0048] The compressive strength of hollow glass microspheres quenched with quenching oil at different heating rates / heat treatment temperatures is shown in Table 3:

[0049] Table 3

[0050]

[0051] By studying the changes in compressive strength of hollow glass microspheres after cooling with different heating rates and quenching media, it was found that the compressive strength reached its maximum value at a heating rate of 5℃ / min. The compressive strength decreased continuously at heating rates of 7.5℃ / min and 10℃ / min, reaching its lowest value at 10℃ / min. Therefore, the optimal heating rate for the powder is 5℃ / min. This is because the strength of hollow glass microspheres is determined by both surface compressive stress and internal tensile stress. During heat treatment, the heating rate affects the distribution of tensile stress within the glass, thus affecting its strength. Rapid heating causes the surface temperature to be higher than the internal temperature, resulting in rapid surface expansion and relative internal contraction. This generates compressive stress on the surface and tensile stress internally, a stress distribution that is beneficial for improving the glass's strength. However, if the heating rate is too fast, insufficient heating can occur, leading to a large temperature difference between the glass surface and interior, resulting in internal cracks. Furthermore, the particle size and melting point of glass microspheres vary, meaning some microspheres cannot reach a molten state, thus reducing their strength. On the other hand, when glass is heated slowly, the internal tensile stress is gradually released, which may lead to a decrease in the glass's strength. Therefore, when heat-treating glass, it is necessary to select an appropriate heating rate based on the specific material and processing requirements to reduce breakage caused by uneven heating or excessively rapid heating, in order to maximize the glass's strength.

[0052] Finally, it should be noted that the above embodiments do not limit the present invention in any way. Those skilled in the art can make modifications and improvements based on the present invention. Therefore, any modifications or improvements made without departing from the spirit of the present invention are within the scope of protection claimed by the present invention.

Claims

1. A method for improving the compressive strength of hollow glass microspheres based on heat treatment and quenching, characterized in that, The method comprises the following steps: (1) high-temperature heat treatment: put the hollow glass microsphere powder into a muffle furnace for high-temperature heat treatment, and when the muffle furnace reaches the set temperature, perform heat preservation; (2) quenching treatment: put the powder after high-temperature heat treatment into a quenching medium for cooling, and then perform suction filtration and drying; In step (1), the heating rate of the muffle furnace is 5 ℃ / min; In step (2), the quenching medium is pure water, quenching oil or a salt solution.

2. The method for improving the compressive strength of hollow glass microspheres by heat treatment and quenching according to claim 1, characterized in that, In step (1), the temperature of high-temperature heat treatment is 500-600 ℃.

3. The method for improving the compressive strength of hollow glass microspheres based on heat treatment and quenching according to claim 2, characterized in that, In step (1), the temperature of high-temperature heat treatment is 580 ℃.

4. The method for improving the compressive strength of hollow glass microspheres by heat treatment and quenching according to claim 1, characterized in that, In step (1), the heat preservation time is 30-40 min.

5. The method for improving the compressive strength of hollow glass microspheres by heat treatment and quenching according to claim 1, characterized in that, In step (2), the quenching medium is a potassium chloride solution.

6. The method for improving the compressive strength of hollow glass microspheres by heat treatment and quenching according to claim 1, characterized in that, In step (2), during cooling, the rotating speed of mechanical stirring is 300-500 r / min, and the mechanical stirring time is 5-10 min.

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