KR20140082722A - Preparation method of foam glass using waste glass, and prediction method of foaming range of glass using dilatometer - Google Patents

Abstract

An aspect of the present invention provides a method to manufacture foam glass using waste glass comprising the steps of: manufacturing a molded body by pressurizing waste glass powder composed of sodium silicate or boroaluminosilicate in a forming mold without adding a foaming agent; and sintering and foaming the molded body at temperatures of 600-1000°C, wherein a method to manufacture the waste glass powder comprises the step of pulverizing waste glass composed of sodium silicate or boroaluminosilicate by a wet pulverization process.

Description

[0001] The present invention relates to a method for manufacturing a foamed glass using waste glass, and a method for predicting the foaming interval of glass using a thermal expansion coefficient measuring apparatus,

The present invention relates to a method for producing a foamed glass and a method for predicting a foamed section, and more particularly, to a method for producing foamed glass using pulverized glass as a raw material without the addition of a foaming agent (or a bubble forming agent) And a method for predicting the foaming section of glass using a glass manufacturing method and an expansion coefficient measuring instrument.

Foamed glass is lightweight and exhibits excellent performance in flame blocking, heat insulation, heat resistance and sound absorption, and is used when industrial waterproofing, heat resistance and durability are required. Especially, it is used as excellent heat insulating material and sound absorbing material in structures and buildings.

The manufacturing principle of foamed glass has already been proposed in the late 1930s. As an example of this, a glass composition of special composition is mixed together with a reducing agent such as carbon and a bubbling agent containing an oxide, sulfate or other types of oxidizing components, and the mixture is pulverized, And the mixture is fired until softening or melting.

During this heat treatment process, a redox reaction takes place between the carbon and the sulfur oxides (or oxidants or oxides of the glass), so that the molten glass contains SO ₂ , CO ₂ , N ₂ , H ₂ S or other gases, It forms a material that forms a low-density, heat-conductive and radiation-resistant structure and forms a glass gas. As a result, if the best results are obtained, the structure of the glass will have airtight pores that are impervious to water, water vapor, or other liquids and gases.

Many research results and related patents have been proposed for the manufacturing process of the foamed glass block manufactured according to such a manufacturing principle. In order to produce foamed glass commercialized by Pittsburg Corning, USA, it is first necessary to prepare raw glass for the production of foamed glass of special composition. To this end, various components such as Na ₂ SO ₄ , CaCO ₃ , MgCO ₃ , Na ₂ O, and As ₂ O ₃ are added to the raw material components for producing glass in order to be foamed glass, Making raw glass for manufacturing foamed glass that can make glass. Then, the thus-produced glass is pulverized, and carbon, which is a foaming agent for producing a gas acting as a direct blowing agent, is added thereto by reacting with the other components, and then the raw glass powder for manufacturing the mixed foamed glass is placed in a certain container Preheated at 400 to 650 占 폚, subjected to a foaming process at a temperature of 800 to 900 占 폚, and subjected to heat treatment such as cooling and slow cooling for stabilization, and then cut into a certain size and packaged and sold.

However, since this process requires a large amount of energy as the heat treatment temperature is 1300 to 1600 占 폚 as described above in the course of making the raw glass for manufacturing foamed glass, and the facility investment and management cost is required, the raw glass for manufacturing foamed glass Production costs account for more than half of the production cost of foamed glass.

On the other hand, it is very important to predict the foaming section of the glass as accurately as possible in the production of the foamed glass. However, many research results and related patents have been proposed for the manufacturing process of the foamed glass block in accordance with this manufacturing principle, but the study on the foamed glass production section is insignificant.

Conventionally, an experiment for accurately predicting the generation time of foamed glass has been carried out at a macroscopic stage through a real-time image using a high-temperature microscope or the like. This can not predict the precise foaming zone of the glass, and there is a limitation that the unit can be measured only in millimeters (mm).

SUMMARY OF THE INVENTION It is an object of the present invention to solve the problems of the prior art and to provide a method of manufacturing an optical glass having an efficient function having a uniform pore distribution without requiring melting, Color or color foamed glass without a foaming agent.

Another object of the present invention is to provide a method of accurately predicting the foaming interval of glass according to various measurement variables such as temperature interval, heating rate, temperature holding time and cooling rate by using an expansion coefficient measuring apparatus.

According to one aspect of the present invention, there is provided a method of producing a molded article, comprising: pressing a waste glass powder of sodium-silicate or boroalumino-silicate composition in a molding mold without adding a foaming agent; And firing and firing the molded body at a temperature in the range of 600 to 1000 ° C, wherein the waste glass powder is a waste glass produced by pulverizing a sodium-silicate or boroaluminosilicate composition waste glass by a wet grinding process There is provided a method of manufacturing a foamed glass using the same.

At least one solvent selected from the group consisting of water, ethyl alcohol, methyl alcohol and acetone may be used as the solvent in the wet pulverization step.

The method may further comprise dry-milling the sodium-silicate or boroaluminosilicate composition waste glass prior to grinding in the wet grinding process.

The size of the waste glass powder may be in the range of 1 to 10 mu m.

The waste glass powder may have a metal oxide added as a colorant, and the metal oxide may be at least one of cobalt oxide (Co ₃ O ₄ ) and manganese oxide (MnO ₃ ).

The metal oxide may be added to the waste glass powder before the firing and foaming step or may be added before the step of pulverizing by the wet grinding process.

According to another aspect of the present invention, there is provided a method of predicting the foaming interval of glass, which predicts the foaming interval of the unexpended precursor using a shape change curve according to the temperature of the unexpended precursor measured by the expansion coefficient measuring equipment.

The shape change curve according to the temperature includes the steps of charging the unexpanded precursor into the expansion coefficient measurement equipment; And measuring the change in length or volume of the unexpanded precursor while raising the temperature of the unexpanded precursor to a temperature at or above the foaming initiation temperature of the unfoamed precursor.

The shape change curve can be obtained under the condition that the vertical load or pushing force is 200 cN or less.

The shape change curve may be obtained by changing at least one of a measured temperature range, a heating rate, a cooling rate, and a temperature holding time. For example, the measurement temperature range can be varied from room temperature to 1400 ° C, the rate of temperature increase is 0.1 to 50 ° C / min, the cooling rate is 0.1 to 50 ° C / min, and the holding time is 24 hours or less .

The unfoamed precursor may be in powder form or in bulk form having a uniform shape.

According to the present invention, since the foamed glass is manufactured through the process control without adding the foam forming agent using the waste disposal waste, the process is simplified, and the foamed glass having a uniform pore structure and excellent aesthetic characteristics can be manufactured It can be used for various construction and environmental related goods.

In the present invention, since the glass foam zone having various parameters can be accurately predicted by analyzing the expansion coefficient measurement equipment, it is helpful to optimize the process control and production process, and accordingly, it is possible to set the accurate foam temperature and the foam And can be usefully used in the production of glass.

The effects of the present invention are not limited to those mentioned above, and other effects not mentioned can be clearly understood by those skilled in the art from the following description.

1 is a flow chart illustrating a process for manufacturing a foamed glass using waste glass according to the present invention.
Fig. 2 shows the microstructure of the foamed glass produced according to Examples 1 to 4 of the present invention.
Fig. 3 shows the appearance of the foamed glass produced according to Example 1 of the present invention.
4 shows the appearance of the foamed glass produced according to Examples 5 to 8 of the present invention.
FIG. 5 shows a shape change curve obtained using an expansion coefficient measuring apparatus according to an embodiment of the present invention.
Fig. 6 shows a shape change curve using the expansion coefficient measuring apparatus according to the ninth to twelfth embodiments of the present invention.
Fig. 7 shows a shape change curve according to the tenth embodiment of the present invention.
FIG. 8 is a result of observation of the microstructure images of the foaming shape at the boundary and before and after the foaming temperature shown in FIG. 7 by an electron microscope.
FIGS. 9A and 9B are cross-sectional views of horizontal and vertical expansion coefficient measurement equipment according to an embodiment of the present invention, which is used in the method of predicting the foamed section of glass.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be understood, however, that the invention is not limited to the disclosed embodiments, but may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, Is provided to fully inform the user. Also, for convenience of explanation, the components may be exaggerated or reduced in size.

The present invention is characterized in that foamed glass is produced by directly foaming waste glass without using any special pretreatment process for the production of foamed glass using waste glass produced in life or industry in general. FIG. 1 is a flowchart showing a stepwise production method of a foamed glass according to an embodiment of the present invention. Hereinafter, a method for producing a foamed glass according to an embodiment of the present invention will be described with reference to FIG.

Referring to FIG. 1, a sodium-silicate or boroalumino-silicate composition waste glass is prepared as a foamed glass raw material (S1). When such sodium-silicate or boroaluminosilicate composition waste glass is used as a raw material for the foamed glass, it is possible to manufacture the foamed glass without addition of an additional foaming agent.

Next, the prepared waste glass is pulverized to produce a raw material powder for foaming (S2). The prepared waste glass is pulverized by a wet grinding process using a grinding apparatus such as a disk mill or a ball mill. At this time, at least one solvent selected from the group consisting of water, ethyl alcohol, methyl alcohol and acetone can be used as the solvent.

The pulverization of the waste glass for efficient pulverization can be carried out through a plurality of steps. For example, the waste glass can be subjected to primary coarse grinding using a dry method and then finely pulverized with a finer powder by a wet grinding process.

The particle size of the pulverized powder is preferably as small as possible, but the size of the powder may be adjusted to be in the range of 1 to 10 탆 in consideration of the economical cost of the powder.

Thereafter, waste glass powder is immersed in a molding mold without adding a foaming agent, and is formed into a molded body by uniaxial and isostatic pressing (S3). The molded article is formed into a foamed glass through sintering and foaming step (S4) at 600 to 1000 ° C (S5).

In the present invention, the generation mechanism of the foamed glass will be described with reference to Equation 1 below.

Equation 1)

As shown in Equation 1, when M in the formula 1 is Na, such as a raw glass having a specific composition, for example, sodium-silicate, when water is added, H ⁺ ions in the water and Na ⁺ ions Are exchanged with each other to form a NaOH alkali solution (1 step). Next, the OH ^- ions of the NaOH alkali solution penetrate the glass and destroy the SiO ₂ grazing structure (2Step). As a result of the hydrolysis, the glassy water or OH ^- component contained in the glass is decomposed to form air bubbles inside the softened or melted glass particles, and the glass particles trapped in the glass particles Bubbles are formed in the resultant glass to form a foamed glass.

The foamed glass produced by the manufacturing process according to the embodiment of the present invention has a uniform micropore structure and can have excellent aesthetics as well as excellent mechanical properties. As an example, the physical properties of the foamed glass produced by the above process can exhibit a density value of 287 kg / m 3, a porosity of 88%, a compressive strength of 1.4 MPa and a thermal conductivity of 0.070 kcal / mh ° C at 25 ° C .

As another embodiment of the present invention, a method of manufacturing color foamed glass having various colors can be provided. The color foamed glass can be realized by adding a metal oxide as a coloring agent to the waste glass powder. The metal oxide used as the coloring agent may be, for example, cobalt oxide (Co ₃ O ₄ ) or manganese oxide (MnO ₃ ). When the waste glass powder to which such a metal oxide is added is fired and foamed, colored foamed glass colored with a specific color can be produced.

The metal oxide, which is a coloring agent, can be added to the process of pulverizing waste glass. For example, waste glass powder can be prepared by adding the metal oxide to the waste glass powder prepared by first pulverizing the prepared waste glass by a dry grinding process, followed by secondary pulverization by a wet grinding process. Alternatively, the metal oxide may be added to the powder which has been subjected to the second pulverization, and then the subsequent steps may be carried out. In addition to this, before the pulverization of the prepared waste glass, the pulverization process is carried out after adding the metal oxide, or the pulverized waste glass is pulverized to prepare the final waste glass powder, and then the metal oxide is added before the molding. Any way you can do is okay.

The manufacturing of the foamed glass according to the embodiment of the present invention basically involves a step of foaming in the process of raising the temperature of the unexpanded precursor. Here, the unfoamed precursor refers to a glass which is in a state where no foaming has occurred yet, or in which the foaming can take place as it is heated. At this time, the unfoamed precursor may be a glass powder or a bulk form having a certain shape (including a molded body formed by pressing a glass powder). By precisely predicting the foaming period of the unexpanded precursor, it becomes possible to control the manufacturing process of the foamed glass more precisely.

Conventionally, in order to predict the section of the foamed glass, a high-temperature microscope was used from a macroscopic point of view. However, according to the method of predicting the glass transition temperature of the glass of the present invention, the length change or the volume change of the molded body caused by foaming under various conditions without using the high temperature microscope can be measured by using the expansion coefficient measuring apparatus, It is possible to predict the foam generation region and behavior of the satisfying glass. As described above, according to the method of predicting the glass transition temperature of the glass according to the present invention, since the thermal behavior of the glass is observed by using the curve for shrinkage or expansion caused by the expansion coefficient measurement device, Temperature range setting is enabled.

The shrinkage and expansion behavior of the glass can be calculated by the following Equation 2 and Equation 3. Based on the equations 2 and 3, it is possible to derive the glass length change or the volume change according to the temperature change.

Equation 2)

Here, α is referred to as a coefficient of liner expansion, which is expressed as a ratio of a rate of change in length to a temperature change.

Equation 3)

The coefficient of volume expansion β is defined as the ratio of the volume change to the minute change with temperature under a constant pressure.

As a technique for obtaining the length change or the volume change necessary for this equation, a thermal analysis technique for measuring a change in length (ΔL) according to temperature and time function under a constant load applied to the sample is a TMA method It can be divided into dilatometry.

TMA is a method of measuring the change in length depending on temperature and function under a constant load, and the Dilato method is a method of measuring a change in length according to temperature and function in a state in which the load is not applied. However, in the ASTM standard and actual measurement, it is common to measure tens of cN of force in TMA, and since the dilatometer method also imposes tens of cN loads, the distinction between the two measurement methods is not significant.

In general, Dilatometer uses a displacement measurement sensor called LVDT (Linear Variable Differential Transformer) to measure the change in length, and consists of a heating furnace for temperature control and a holder for sample fixing.

The expansion coefficient measurement apparatus can be divided into a horizontal type as shown in FIG. 9A and a vertical type as shown in FIG. 9B. The horizontal type is to load the specimen holder 90a containing the specimen 91a horizontally into the heating furnace 92a while vertically placing the specimen holder 90b containing the specimen 91b perpendicularly to the heating furnace 92b Charge. Thermocouples 94a and 94b for measuring the temperatures of the test pieces 91a and 91b both in the horizontal and vertical types can be provided. A predetermined load can be applied to the test pieces 91a and 91b through push rods 93a and 93b. For example, in the case of a horizontal expansion coefficient measuring device, measurement can be performed under the condition that the pushing force of the push rod 93a is less than 200 cN. In the case of the vertical expansion coefficient measuring device, . ≪ / RTI > In the case of the vertical expansion coefficient measurement device, it is also possible to measure by applying only the vertical load corresponding to the self-load of the push rod 93b.

It is possible to measure the temperature under the pushing force condition using the horizontal expansion coefficient measuring instrument and the measurement under the vertical load condition using the vertical expansion coefficient measuring instrument so that it is possible to set the optimum temperature condition for the formation of the foamed glass .

The use of such an expansion coefficient measuring device can grasp the shrinkage and expansion behavior of the unfoamed precursor to understand the transition process to the foamed glass in real time. Further, the change of the heating rate, the holding time and the cooling rate change The foam generation behavior can be observed and analyzed from the macroscopic and microscopic viewpoints.

For example, while changing the heating zone in the range of room temperature to 1400 占 폚, the heating rate in the range of 0.1 占 폚 to 50 占 폚 per minute, the temperature holding time in the range of 0 to 24 hours, and the cooling rate in the range of 0.1 占 폚 to 20 占 폚, It is possible to observe the foaming behavior due to shrinkage and expansion in real time.

Hereinafter, a method of predicting the foaming interval of glass will be described in detail with reference to the drawings.

FIG. 5 shows a curve (referred to as a shape change curve) showing an example of the shrinkage and expansion behavior of sodium-silicate glass obtained using a horizontal expansion coefficient measuring apparatus. Specifically, the shape change curve was obtained by charging a molded product of sodium-silicate glass powder into an expansion coefficient measuring apparatus, raising the temperature from room temperature to 700 ° C at a heating rate of 5 ° C / min under a load of 25 cN, maintaining the temperature at 700 ° C for 120 minutes, Such as glass length or volume, generated during the cooling time to room temperature at a cooling rate of < RTI ID = 0.0 > C / min. ≪ / RTI >

In FIG. 5, the x-axis represents time, the y-axis on the left represents linear shrinkage (ΔL / L,%), and the y-axis on the right represents temperature. Fig. 5 (a) shows a change in temperature with time, and Fig. 5 (b) shows a shape change curve showing shrinkage and expansion behavior of sodium-silicate glass corresponding to this temperature change.

Referring to the shape change curve shown in FIG. 5, as the temperature increases, the shrinkage of the glass linearly occurs until the foaming point. However, as the holding time increases from the foaming point at about 600 ° C, As the foaming of the foaming precursor occurs, a section in which the volume linearly increases in the same manner as in the interval 2 is generated. Section 3 shows the volume change of the glass as the temperature decreases. It can be observed in real time that the shrinkage of the foamed glass with the decrease of the cooling temperature and the occurrence of the crack occurred during the cooling.

As described above, according to the foam zone measuring method according to the embodiment of the present invention, it is possible to measure the foaming zone of the glass in real time by measuring the shape change such as the length change or the volume change during the foaming process of the glass. Therefore, when the foaming section measuring method is used, it is possible to know the foaming characteristics according to various foaming conditions, for example, the temperature condition, the temperature raising condition and the holding time condition. Therefore, based on the data on the foaming characteristics, It becomes possible to perform optimization of various conditions suitable for the production of glass.

Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited to the following examples.

Example  1 ~ 4: Manufacture of foam glass using waste glass

Sodium-silicate composition Waste glass was first pulverized using a disk mill. The pulverization conditions were pulverized by the recycling method up to three times. The first pulverized powder (average 120 탆) was subjected to secondary wet pulverization (average 2 탆) using distilled water as a solvent at a speed of 100 to 400 rpm for 1 to 72 hours using a planetary mill.

The second pulverized powder was dried in an oven at 60 DEG C for 24 hours. The dried powder was sieved using a 200 mesh sieve. The unfired precursor was produced by putting a sintered powder as a non-foam precursor into a molding mold and molding it by a press-press method. The unfoamed precursor was heated at a rate of 1, 5, 10 and 20 ° C / min from room temperature to 700 ° C using an electric furnace, and then heated and fired for 2 hours to prepare a foamed glass (Example 1 to 4). Table 1 shows specific conditions of Examples 1 to 4.

FIGS. 2A to 2D show the results of observing the microstructure of the foamed glass produced according to Examples 1 to 4 of the present invention by an electron microscope. Referring to FIGS. 2A to 2D, it can be seen that uniformly formed pores are distributed in the manufactured foamed glass, and it can be seen that the average size of the pores increases with an increase in the heating rate. In addition, the appearance of the foamed glass of Example 2 was observed, and as a result, the appearance of the foamed glass of Example 2 was observed as an example.

Example  5 ~ 8: Manufacture of Foamed Glass with Aesthetic Property Using Waste Glass

Examples 5 to 8 relate to color foamed glass colored with a predetermined hue on the foamed glass of Examples 1 to 4. Specifically, in the same manner as in Examples 1 to 4, sodium-silicate waste glass was firstly pulverized using a disk mill. 1 or 2 wt% of cobalt oxide (Co ₃ O ₄ ) or manganese oxide (MnO ₃ ) was added as a coloring agent to the primary pulverized powder (average 120 μm), and distilled water was used as a solvent. (Average 2 [mu] m) for a period of time.

The second pulverized powder was dried in an oven at 60 DEG C for 24 hours. The dried powder was sieved using a 200 mesh sieve. The sieved powder was placed in a molding mold and molded by a press-press method to prepare an unfoamed precursor. The above unfoamed precursor was subjected to a firing and foaming process at 700 ° C for 2 hours under a condition of 5 ° C per minute at a heating rate using an electric furnace to prepare foamed glass having various colors. Table 2 shows the specific conditions of Examples 5 to 8 and the hue of the foamed glass.

FIG. 4 shows the results of observing the hue of the foamed glass produced according to Examples 5 to 8 of the present invention in the order of upper left, upper right, lower left and lower right.

Referring to the upper left and upper right portions of FIG. 4, when 1 wt% of cobalt oxide (Co ₃ O ₄ ) was added, the density was 297 kg / m 3 and gray. However, as the content of cobalt oxide increased to 2 wt% The color of the glass showed a very good aesthetic bright blue system and the density increased to 476 kg / ㎥. This is probably due to the difference in the foaming properties of the glass depending on the amount of cobalt oxide (Co ₃ O ₄ ) added.

On the other hand, referring to the lower left and lower right of FIG. 4, When 1 wt% of manganese oxide (MnO ₃ ) was added, the density was 202 kg / m ₃ , and the density was 306 kg / m 3 when 2 wt% was added.

From this, it can be understood that the foamed glass having desired color and density can be manufactured by appropriately controlling the addition amount of the colorant considering both the color and the density of the foamed glass.

Example  9 ~ 12: Prediction of glass foaming zone using expansion coefficient measurement equipment

Unfoamed precursors were prepared by sieving of powders and molding using a molding mold to predict the foamed glass section using sodium-silicate glass. The prepared unfoamed precursor was loaded into the expansion coefficient measuring device and the behavior of the foamed glass was observed in real time while changing the heating rate at 1, 5, 10, and 20 ° C / minute as shown in Table 3 while applying a load of 25 cN (Examples 9 to 12).

FIG. 6 shows a shape change curve showing the shrinkage and expansion behavior of the unexpanded precursor when the temperature raising rate is changed to 1, 5, 10, or 20 ° C per minute. Referring to FIG. 6, when the temperature is increased, the unexpanded precursor shrinks linearly, but the volume is linearly expanded due to the bubbles formed by foaming from a certain temperature, that is, the foaming initiation temperature. At this time, it can be confirmed that the foaming initiation temperature of the unexpanded precursor tends to increase as the heating rate increases.

FIG. 7 is a graph showing a shape change curve according to temperature when the temperature raising rate is 5 ° C / min, and it is shown that the foaming start temperature is 693 ° C.

8A, 8B and 8C show the microstructure of the foamed glass at 673 DEG C, 693 DEG C and 713 DEG C shown in Fig.

Pores are not observed at the temperature lower than the foaming initiation temperature (Fig. 8A), but pores are observed at the foaming initiation temperature (Fig. 8B) and relatively coarse at a temperature higher than the foaming initiation temperature It can be seen that the generated pores are observed.

From these results, it can be confirmed that foamed glass having optimal physical properties can be manufactured by controlling and setting the foaming conditions using the foam behavior curve in the production of foamed glass.

The foregoing description of specific embodiments of the invention has been presented for purposes of illustration and description. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention as defined by the appended claims. Do.

Claims (14)

Pressurizing the waste glass powder of sodium-silicate or boroalumino-silicate composition in a molding mold without adding a foam former to produce a molded article; And
And firing and firing the molded body at a temperature range of 600 to 1000 ° C,
The method for producing waste glass powder includes:
Sodium silicate or boroalumino-silicate composition comprising a step of grinding waste glass by a wet grinding process. The method for producing a foamed glass according to claim 1, wherein at least one solvent selected from the group consisting of water, ethyl alcohol, methyl alcohol and acetone is used as the solvent in the wet pulverizing step. The method of claim 1, further comprising dry-milling the sodium-silicate or boroaluminosilicate composition waste glass prior to grinding in the wet grinding process. The method of claim 1, wherein the size of the waste glass powder is in the range of 1 to 10 mu m. The method for producing a foamed glass according to claim 1, wherein the waste glass powder has a metal oxide added as a colorant. The method for producing a foamed glass according to claim 5, wherein the metal oxide is at least one of cobalt oxide (Co ₃ O ₄ ) and manganese oxide (MnO ₃ ). 7. The method of claim 6, wherein the metal oxide is added to the waste glass powder prior to the firing and foaming steps. 8. The method of claim 7, wherein the metal oxide is added prior to grinding in the wet grinding process. A method for predicting the foaming interval of a glass, wherein the foaming interval of the unfoamed precursor is predicted using a shape change curve according to the temperature of the unfoamed precursor measured by a coefficient of expansion measuring equipment. The method according to claim 9, wherein the shape change curve according to the temperature
Charging the unexpanded precursor into the expansion coefficient measurement equipment; And
Measuring the change in length or volume of the unexpanded precursor while raising the temperature of the unexpanded precursor to a temperature at or above the foaming initiation temperature of the unexpanded precursor;
Wherein the predicted foaming interval of the glass is obtained. 10. The method according to claim 9, wherein the shape change curve is obtained under a condition that a vertical load or a pushing force is 200 cN or less. The method according to claim 9, wherein the shape change curve is obtained while changing at least one of a measured temperature range, a heating rate, a cooling rate, and a temperature holding time. The method according to claim 11, wherein the measured temperature range is from room temperature to 1400 占 폚, the heating rate is from 0.1 to 50 占 폚 / min, the cooling rate is from 0.1 to 50 占 폚 / min, , A method for predicting the foaming interval of glass. The method of claim 9, wherein the unfoamed precursor is in the form of a powder or a bulk having a uniform shape.

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