阅读说明：本技术 一种低熔体表面张力的tft基板玻璃及其制备方法 (TFT substrate glass with low surface tension and preparation method thereof ) 是由 田英良 李淼 赵志永 杨国洪 王为 杨智 于 2020-12-28 设计创作，主要内容包括：本发明提供一种低熔体表面张力的TFT基板玻璃及其制备方法,所述TFT基板玻璃的组分按摩尔比计,包括58-68份的SiO-2、8-13份的B-2O-3、9-15份的Al-2O-3、6-10份的CaO和1-3份的SrO；所述的B-2O-3通过硼酸和硼矸引入,Al-2O-3通过氢氧化铝和氧化铝引入,SrO通过碳酸锶和硝酸锶引入。TFT基板玻璃在制备时,按摩尔比计,将58-68份的SiO-2、8-13份的B-2O-3、9-15份的Al-2O-3、6-10份的CaO和1-3份的SrO采用全氧燃烧方式和电助熔方式共同熔化成玻璃熔体,之后将得到的玻璃熔体用溢流法进行制备,得到低熔体表面张力的TFT基板玻璃。(The invention provides TFT substrate glass with low surface tension and a preparation method thereof, wherein the components of the TFT substrate glass comprise 58-68 parts of SiO according to molar ratio 2 8-13 parts of B 2 O 3 9-15 parts of Al 2 O 3 6-10 parts of CaO and 1-3 parts of SrO; b is 2 O 3 By introducing boric acid and boron gangue, Al 2 O 3 The SrO is introduced by strontium carbonate and strontium nitrate, by aluminum hydroxide and aluminum oxide. In the preparation of TFT substrate glass, 58-68 parts of SiO by molar ratio 2 8-13 parts of B 2 O 3 9-15 parts of Al 2 O 3 6 to 10 portions of CaO and 1 to 3 portions of SrO are jointly melted into glass melt by adopting a total oxygen combustion mode and an electric boosting mode, and then the obtained glass isThe glass melt is prepared by an overflow method, and the TFT substrate glass with low surface tension is obtained.)

1. The TFT substrate glass with low surface tension is characterized in that the components of the TFT substrate glass comprise 58-68 parts of SiO according to molar ratio₂8-13 parts of B₂O₃9-15 parts of Al₂O₃6-10 parts of CaO and 1-3 parts of SrO;

b is₂O₃By introducing boric acid and boron gangue, Al₂O₃The SrO is introduced by strontium carbonate and strontium nitrate, by aluminum hydroxide and aluminum oxide.

2. The low melt surface tension TFT substrate glass according to claim 1, wherein B is introduced with boric acid₂O₃Account for B₂O₃60-80% of the total amount, B introduced by boron gangue₂O₃Account for B₂O₃20-40% of the total amount.

3. The low melt surface tension TFT substrate glass according to claim 1, wherein aluminum hydroxide-introduced Al₂O₃Is Al₂O₃30-50% of the total amount, and Al introduced by alumina₂O₃Is Al₂O₃50-70% of the total amount.

4. The low-melting-surface-tension TFT substrate glass according to claim 1, wherein strontium carbonate-introduced SrO accounts for 0 to 40% of the total amount of SrO, and strontium nitrate-introduced SrO accounts for 60 to 100% of the total amount of SrO.

5. The low melt surface tension TFT substrate glass of claim 1, further comprising in terms of mole ratios, not more than 4 parts MgO and not more than 1 part BaO.

6. The low bulk surface tension TFT substrate glass of claim 1, further comprising not more than 0.3 parts SnO₂。

7. A preparation method of TFT substrate glass with low surface tension is characterized in that 58-68 parts of SiO is added according to molar ratio₂8-13 parts of B₂O₃9-15 parts of Al₂O₃Melting 6-10 parts of CaO and 1-3 parts of SrO into glass melt by adopting a total oxygen combustion mode and an electric boosting mode, and preparing the obtained glass melt by using an overflow method to obtain TFT substrate glass with low surface tension;

in which boric acid is incorporated B₂O₃Account for B₂O₃60-80% of the total amount, B introduced by boron gangue₂O₃Account for B₂O₃20% -40% of the total amount, B introduced by boric acid₂O₃Account for B₂O₃60-80% of the total amount, B introduced by boron gangue₂O₃Account for B₂O₃20-40% of the total amount, and Al introduced by aluminum hydroxide₂O₃Is Al₂O₃30-50% of the total amount, and Al introduced by alumina₂O₃Is Al₂O₃50-70% of the total amount.

8. The method for preparing TFT substrate glass with low surface tension according to claim 7, wherein the total oxygen combustion mode provides 20% -40% of glass melting energy, and the formed kiln flue gas pressure is 10-30 Pa.

9. The method of claim 7, wherein the tin oxide electrode is laterally disposed on the melting tank side to provide 60-80% of the glass melting energy.

10. A TFT substrate glass with low surface tension obtained by the method for producing a TFT substrate glass with low surface tension according to any one of claims 7 to 9.

Technical Field

The invention relates to the technical field of TFT substrate glass forming, in particular to TFT substrate glass with low surface tension and a preparation method thereof.

Background

Surface tension is one of the important physical parameters of liquid substances, and reflects the important interfacial properties of multiphase (i.e. solid, liquid, gas) systems. The surface tension of the glass melt has extremely important significance in the production and manufacturing process of glass products, and particularly plays a significant role in the clarification, homogenization, shaping, glass processing and other processes of the glass melt. The growth, dissolution and expulsion rates of bubbles in the molten glass (melt) are affected to some extent by the action of surface tension. The relative size of the surface tension of the main body glass and the surface tension of the stripe glass determines the diffusion and dissolution speed of the stripes and the nodules, if the surface tension of the stripe glass is greater than the surface tension of the main body glass, the stripes are required to be spherical and not easy to spread and dissolve, and if the surface tension of the stripe glass is less than the surface tension of the main body glass, the stripes are required to be spread into a film and are easy to diffuse and dissolve. The drawing of glass tubes and rods requires spontaneous development of the glass into a cylindrical shape by surface tension effects. The fire polishing of the glass also makes the surface of the glass smoother by virtue of the surface tension effect. Surface tension can also have adverse effects on the production of glass products, for example, in the production of flat glass, the surface tension of glass melt can cause shrinkage, and therefore needs to be overcome by an edge roller, and the surface tension of the glass melt plays an important role in guiding the production and manufacture of glass.

Currently, Liquid Crystal Displays (LCD) and Organic Light-Emitting displays (OLED) have become the two most important Display products. LCD has a relatively long history of development since 1883After that, twisted nematic liquid crystal display technology (abbreviated as TN-LCD) was implemented in 1968, and thereafter products were implemented in japan for calculators and watches; super-twisted liquid crystal display technology (abbreviated as STN-LCD) was realized in 1986 to 1992, and color effects began to be exhibited for game machines and notebook computers; in 1993, a thin film silicon transistor liquid crystal display product (TFT-LCD) has better display effect, realizes real color effect, starts to replace a cathode ray tube display (CRT), reaches the maximum specification of 27 inches, and the composition of substrate glass has been developed into alkali-free aluminoborosilicate (namely R-borosilicate)₂O-Al₂O₃-B₂O₃-SiO₂) A glass system. In 2004, the LCD is in a continuously prosperous and fast developing stage, the product is developed to large-scale, ultra-Thin and high-definition, and comprehensively replaces the CRT television product, the display quality is better, the maximum size of the LCD panel reaches 2940 × 3370mm (i.e. G11 generation), the Thin Film Transistor (abbreviated as TFT) driving circuit is gradually changed from amorphous silicon (i.e. a-Si) to polysilicon (i.e. p-Si), the circuit can be finer, the conductivity is better, the display aperture ratio is larger, the color is brighter, the pixel is more miniaturized, and the image is more vivid. The OLED display finds the light emitting principle from 1936 until the Duncui cloud professor and Van Slyke develop and develop a double-layer organic light emitting device in 1987, so that the development of OLED is hot worldwide, and the Qiuhong professor team in Qinghua university synchronously develops research and development and industrialization, the OLED does not need backlight, has high contrast, thin thickness, wide viewing angle and high reaction speed, can be used for rigid/flexible OLED display, is applied to small-size display products in 2003, is applied to television products in 2013, and becomes a new favorite in the industry after LCD display in recent years, and the OLED display industry is rapidly developed in China and Korea.

The TFT substrate glass is a key basic material for supporting the development of LCD and OLED display industries, and an LCD display product is formed by combining two pieces of substrate glass, is respectively used as a bearing basis of a TFT and a CF (color film), and has the functions of flatness, insulativity, heat resistance, low expansion and light transmittance, so the TFT substrate glass is called as the substrate glass. The TFT substrate glass is required for the vapor deposition of silicon forming the basis of the transistor array; the CF substrate glass is used for carrying CF materials and realizing RGB (red, green and blue) color expression, and the accurate alignment of the CF substrate glass and the TFT substrate glass is very important for the display effect of the LCD device.

The geometric requirements of the TFT substrate glass and the CF substrate glass are substantially the same, but the chemical stability requirements of the TFT substrate glass are more stringent. To date, TFT substrate glass has mainly three substance forms: a-Si, IGZO, p-Si. Most LCDs use amorphous silicon (a-Si) to fabricate TFTs. The a-Si process involves a low temperature consolidation step, typically with exposure to less than 350 ℃ for 1 hour or less; if the a-Si layer is subjected to careful thermal cycling, it will crystallize substantially into fine, sub-pixel sized crystals called polysilicon (p-Si). p-Si is widely used in OLED displays as well as in LCD displays, and low temperature poly-silicon (LTPS) process is widely used in p-Si TFTs, with peak processing temperatures typically not exceeding 600 ℃ and processing times ranging from a few minutes to an hour.

No matter LCD substrate glass or OLED substrate glass, transparent ultrathin glass materials with perfect, flat and smooth surfaces and uniform thickness are required, the thickness range of the substrate glass is 0.4-0.7 mm, the thickness range is mainly three specifications of 0.4mm, 0.55mm and 0.7mm, the thickness difference is less than 0.05mm, the waviness is less than 0.1 mu m, lambda is 0.8-8 mm, Ls is 20mm, and the internal defect is less than or equal to 100 mu m.

Currently, the best process method for producing high-precision substrate glass is the overflow method, and with the progress of the substrate glass from the G4.5 generation (730 × 920mm size specification) to the G11 generation (2940 × 3370mm size specification), it is difficult to achieve ultra-thin production, and it is important to control thickness difference.

In the glass melting process, the elimination of solid-phase particles and gaseous substances of the batch materials is satisfied, and the components of the glass are required to be uniform. The melting temperature of the substrate glass is generally higher than 1650 ℃, the substrate glass is one of the glass varieties with the greatest melting difficulty at present, in order to solve the melting difficulty of the substrate glass, a full-oxygen combustion-assisted electric melting mode is widely adopted, a gas (fuel gas) electric composite melting technology is called for short, and the energy ratio is generally gas (6-8) and electric energy (2-4).

The surface tension of the glass melt is a crucial technological parameter for ultra-thin forming of the substrate glass, the retraction effect of the melt caused by the surface tension is overcome in the ultra-thin forming process, great harm is generated to transverse widening and thinning, the larger the surface tension value of the glass melt is, the more difficult the TFT substrate glass is to be stretched and thinned, the larger the thickness difference size is, the thickness uniformity is crossed, although in engineering, the overflow method primarily realizes the transverse spreading effect by means of the edge-drawing roller effect on two sides, but the fine control of the TFT substrate glass used for the LCD or OLED display products is required to be extremely high. Therefore, it is beneficial to control the surface tension of the glass melt to be reduced for the high-precision ultra-thin forming of TFT substrate glass. How to realize the reduction of the surface tension of a glass melt on the premise of not changing the chemical composition of the substrate glass of an alkali-free aluminoborosilicate glass system and further improve the high-precision forming of the TFT substrate glass of high generation (namely G8.5 generation and above, and the specification size is more than 2200 × 2500mm) is a problem to be solved urgently.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides TFT substrate glass with low surface tension and a preparation method thereof, which are used for increasing hydroxyl (OH) in a TFT substrate glass melt under the premise of unchanging the chemical composition of a TFT substrate glass main body^-) The content of (A) was determined to obtain a TFT substrate glass having a low surface tension.

The invention is realized by the following technical scheme:

the TFT substrate glass with low surface tension comprises 58-68 parts of SiO (silicon dioxide) by molar ratio₂8-13 parts of B₂O₃9-15 parts of Al₂O₃6-10 parts of CaO and 1-3 parts of SrO;

b is₂O₃By introducing boric acid and boron gangue, Al₂O₃The SrO is introduced by strontium carbonate and strontium nitrate, by aluminum hydroxide and aluminum oxide.

Preferably, B is introduced via boric acid₂O₃Account for B₂O₃60-80% of the total amount, B introduced by boron gangue₂O₃Account for B₂O₃20-40% of the total amount.

Preferably, aluminum hydroxide-introduced Al₂O₃Is Al₂O₃30-50% of the total amount, and Al introduced by alumina₂O₃Is Al₂O₃50-70% of the total amount.

Preferably, the strontium carbonate-introduced SrO accounts for 0-40% of the total SrO, and the strontium nitrate-introduced SrO accounts for 60% -100% of the total SrO.

Preferably, the composition of the TFT substrate glass further includes not more than 4 parts of MgO and not more than 1 part of BaO in terms of molar ratio.

Preferably, the coating also comprises SnO with the weight not more than 0.3 part₂。

A TFT substrate glass with low surface tension is prepared from SiO 58-68 parts by mole ratio₂8-13 parts of B₂O₃9-15 parts of Al₂O₃Melting 6-10 parts of CaO and 1-3 parts of SrO into glass melt by adopting a total oxygen combustion mode and an electric boosting mode, and preparing the obtained glass melt by using an overflow method to obtain TFT substrate glass with low surface tension;

in which boric acid is incorporated B₂O₃Account for B₂O₃60-80% of the total amount, B introduced by boron gangue₂O₃Account for B₂O₃20% -40% of the total amount, B introduced by boric acid₂O₃Account for B₂O₃60-80% of the total amount, B introduced by boron gangue₂O₃Account for B₂O₃20-40% of the total amount, and Al introduced by aluminum hydroxide₂O₃Is Al₂O₃30-50% of the total amount, and Al introduced by alumina₂O₃Is Al₂O₃50-70% of the total amount.

Further, the total oxygen combustion mode provides 20% -40% of glass melting energy, and the formed kiln smoke pressure is 10-30 Pa.

Still further, in the electric boosting mode, tin oxide electrodes are arranged on the side of the melting tank for heating, and 60% -80% of glass melting energy is provided.

A TFT substrate glass with low surface tension obtained by the method for preparing a TFT substrate glass with low surface tension.

Compared with the prior art, the invention has the following beneficial technical effects:

according to the TFT substrate glass with low surface tension, the surface tension of the TFT substrate glass melt can be regulated and controlled by the content of hydroxyl in the glass melt, so that the hydroxyl (OH) in the TFT substrate glass melt is subjected to the condition that the chemical composition of the main body of the TFT substrate glass is not changed^-) Adjusting the content of B by introducing boric acid and boron gangue₂O₃Introduction of Al by means of aluminium hydroxide and aluminium oxide₂O₃SrO is introduced through strontium carbonate and strontium nitrate, so that hydroxyl groups are added in raw materials, and then the hydroxyl groups (OH) are finally changed by matching with a total oxygen combustion mode, an electric boosting mode and a corresponding preparation process^-) The content of (3) is such that a TFT substrate glass having a low surface tension can be obtained.

The invention relates to a preparation method of TFT substrate glass with low surface tension, which comprises the steps of firstly preparing 58-68 parts of SiO₂8-13 parts of B₂O₃9-15 parts of Al₂O₃6 to 10 portions of CaO and 1 to 3 portions of SrO are melted into glass melt by a total oxygen combustion mode and an electric boosting mode, B₂O₃By introducing boric acid and boron gangue, Al₂O₃By introducing aluminum hydroxide and aluminum oxide and introducing SrO through strontium carbonate and strontium nitrate, hydroxyl is added in the raw materials, the content of the final hydroxyl is increased through a total oxygen combustion mode and an electric boosting mode, and then the obtained glass melt is prepared by an overflow method, so that the high-precision ultrathin forming of TFT substrate glass is facilitated, and the TFT substrate glass with low melt surface tension meeting the actual requirement can be obtained.

Drawings

FIG. 1 is a representation of ellipsoidal droplets of the invention as the surface tension of a glass melt is measured.

Detailed Description

The present invention will now be described in further detail with reference to specific examples, which are intended to be illustrative, but not limiting, of the invention.

According to the TFT substrate glass with low surface tension and the preparation method thereof, disclosed by the invention, in order to reduce the surface tension of the TFT substrate glass melt, experiments show that hydroxyl (OH) in the TFT substrate glass melt at the early stage of scheme design^-) The content of (2) can regulate and control the surface tension of the TFT substrate glass melt, and under the precondition that the chemical composition of the main body of the TFT substrate glass is not changed, the change of the surface tension of the TFT substrate glass melt can be realized when the hydroxyl content in the TFT substrate glass melt is changed, and the rule of the change accords with the following relational expression:

σ_OH＝σ₀+b/(OH^-+ c) of which σ_OHThe surface tension of the TFT substrate glass melt with a certain hydroxyl concentration content is mN/m (milli-newtons per meter); sigma₀The surface tension of the TFT substrate glass melt with the concentration content of hydroxyl group of 0 is expressed in mN/m (milli-newtons per meter); OH group^-The content of hydroxyl in TFT substrate glass is ppm; b. c is a constant.

According to the invention, the content of hydroxyl in the TFT substrate glass melt is changed by adjusting the raw material source mode and the combustion mode of the glass batch, the source of hydroxyl is added in the raw material, and the final content of hydroxyl is further improved by oxy-fuel combustion.

The TFT substrate glass with low surface tension comprises SiO in mol percentage₂ 58％-68％，B₂O₃ 8％-13％，Al₂O₃ 9％-15％，CaO 6％-10％，MgO 0-4％，SrO 1％-3％，BaO 0-1％，SnO₂0-0.3%, because the invention only changes the sources of the components, and the proportion of the components is not improved, the corresponding action mechanism is not described in detail.

The invention relates to a preparation method of TFT substrate glass with low surface tension, which specifically comprises the following steps:

step 1, introducing the SiO with the dosage through quartz sand₂Boric acid and boron gangue are co-introduced into the mixture in the amount of B₂O₃Hydrogen and oxygenThe aluminum oxide and the aluminum oxide are jointly introduced into the Al with the above dosage₂O₃The amount of CaO, the amount of MgO and the amount of BaO are respectively corresponding carbonates, the amount of SrO is introduced together through strontium carbonate and strontium nitrate, the strontium nitrate and tin oxide form redox effect to further promote the clarification of the glass melt, and the amount of tin oxide is directly introduced into SnO₂。

Boric acid-introduced B₂O₃Account for B₂O₃60-80% of the total amount, B introduced by boron gangue₂O₃Account for B₂O₃20-40% of the total amount.

Aluminum hydroxide-introduced Al₂O₃Is Al₂O₃30-50% of the total amount, and Al introduced by alumina₂O₃Is Al₂O₃50-70% of the total amount.

SrO introduced by strontium carbonate accounts for 0-40% of the total amount of SrO, and SrO introduced by strontium nitrate accounts for 60-100% of the total amount of SrO.

And 2, melting the components by adopting an oxy-fuel combustion mode and an electric boosting mode, wherein the oxy-fuel combustion provides 20-40% of glass melting energy, the pressure of the flue gas of the kiln is 10-30Pa, the electric boosting provides 60-80% of the glass melting energy, tin oxide electrodes are laterally arranged on a melting tank for heating, and then the components are prepared by adopting an overflow method in steps 3-7.

And 3, completely converting the completely melted TFT substrate glass batch into a glass melt, completely eliminating solid-phase particles, eliminating most bubbles to obtain the glass melt with relatively good quality, then enabling the glass melt to enter an upward-inclined platinum channel, reducing kinetic energy and pressure of tiny bubbles in the glass melt along with the rise of fluid, further removing the bubbles, and realizing that the number of bubbles larger than 30 microns in 100kg of the glass melt is less than 2.

And 4, allowing the glass melt with the bubbles fully discharged to enter a platinum stirring bin, and homogenizing under the action of a stirring paddle.

And 5, further cooling and adjusting the temperature of the homogenized glass melt, flowing into an L-shaped platinum pipe along a platinum channel, and injecting into an overflow groove of the overflow brick.

And 6, after the overflow groove is filled with the glass melt, uniformly flowing out along two sides of the overflow groove, flowing and collecting along the wedge-shaped surface of the overflow brick to form a glass ribbon, and sequentially realizing thinning and shaping of the glass melt in a transverse edge-drawing machine and a longitudinal tractor.

And 7, annealing the shaped ultrathin glass plate with uniform thickness, and cutting the ultrathin glass plate under the action of a transverse cutting machine to form the TFT substrate glass sheet.

Hydroxyl (OH) groups in a glass-forming melt prepared by a combination of the above techniques^-) The content can reach 250ppm-350ppm, which is beneficial to the reduction of the surface tension of the glass melt. The surface tension and the hydroxyl content of the TFT substrate glass melt conform to the relational expression sigma_OH＝σ₀+b/(OH^-+ c) of which σ₀293.5mN/m, b 5681.6 and c 59.71. The surface tension of the glass melt is 307-312mN/m when the hydroxyl content is 250-350 ppm, and 383mN/m when the hydroxyl content of the substrate glass is 10ppm, and the surface tension is reduced by more than 19.8 percent relative to the initial zero hydroxyl surface tension. The thickness difference of the formed glass is less than 0.03mm, the waviness is less than 0.05 mu m (the testing parameters are that lambda is 0.8-8 mm, Ls is 20mm), and the internal defects (bubbles, stones and crystal grains) are less than or equal to 30 mu m.

The invention takes the LCD substrate glass of the amorphous silicon process technology and the OLED substrate glass of the polysilicon process technology as the implementation effect analysis.

Example 1

The invention uses the LCD substrate glass of the amorphous silicon process technology as the implementation effect analysis.

Taking the mole percentage of the chemical composition of a typical LCD substrate glass as an example, wherein: SiO 2₂ 65，B₂O₃ 11，Al₂O₃10，CaO 10，MgO 2，SrO 1，BaO 1，SnO₂ 0，

It should be noted that:

boric acid-introduced B₂O₃Account for B₂O₃60% of the total amount, B introduced by boron gangue₂O₃Account for B₂O₃40% of the total amount.

Aluminum hydroxide-introduced Al₂O₃Is Al₂O₃30% of the total amount, alumina-incorporated Al₂O₃Is Al₂O₃70% of the total amount.

The SrO introduced by strontium carbonate accounts for 40% of the total SrO, and the SrO introduced by strontium nitrate accounts for 60% of the total SrO.

And 2, during melting of the components, the total oxygen is combusted to provide 20% of glass melting energy, and the pressure of the kiln smoke is 10 Pa.

And 3, preparing the glass according to the preparation flow of the LCD substrate glass of the amorphous silicon process technology.

Examples 2 to 9

Example 2

The invention takes the OLED substrate glass of the polysilicon processing technology as the implementation effect analysis.

Since this example differs from example 1 only in parameters and examples 3 to 9 differ from example 1 only in parameters, these information and the data of hydroxyl group content and surface tension in the resulting glass melt are shown in table 1.

Table 1 glass processing and related parameters, hydroxyl content in the glass melt, surface tension data in examples 1-9

The method for measuring and characterizing the content of hydroxyl in the glass melt and the method for measuring and characterizing the surface tension of the glass melt are as follows:

the characterization method for measuring the content of hydroxyl in the glass melt adopts infrared spectroscopy. Infrared spectrum 3560cm based on hydroxyl pairs^-1～3840cm^-1Generating obvious absorption in the range, and obtaining the hydroxyl concentration C according to the Lambert beer law and the hydroxyl parameters of the ionized water_OH ^-Thickness d of glass and 3560cm^-1～3840cm^-1The transmittance is expressed by：C_OH ^-＝1000*lg[(T₃₈₄₀/T₃₅₆₀)/d]In which C is_OH ^-Hydroxyl content in ppm; d is the thickness of the glass in mm; t is₃₈₄₀Is 3840cm^-1Maximum transmittance in units of% around; t is₃₅₆₀Is 3560cm^-1The minimum transmittance in% around.

The surface tension measurement and characterization method of the glass melt adopts a sitting drop method, the applicant formulates the method into a national standard, and the method is submitted to the national standard administration committee to issue, and the basic test process is as follows:

a) before the test, 6 samples are prepared, whether the heating furnace is in an initial state or not is checked, and the power supply of the heating furnace is turned on after the initial state is confirmed;

b) opening a gas system, and introducing nitrogen into the heating furnace at a flow rate of 1-3L/min;

c) placing a graphite bearing plate on a bracket by medical forceps, placing the bracket in a heating furnace, taking 1 sample out of a dryer, placing the sample in the center of the graphite bearing plate, heating at (10 +/-5) ° C/min, observing the morphological change of the sample in the heating process, recording the temperature of the sample converted into an ellipsoid shape, and taking the temperature as a test temperature;

d) randomly taking out 1 sample from the rest samples in the dryer by using medical tweezers, and then weighing the mass of the sample by using an electronic balance, wherein the mass is recorded as m and the unit is g;

e) quickly moving the bracket out of the heating furnace, quickly replacing the graphite bearing plate and the sample, wherein the sample is positioned in the center of the graphite bearing plate, and then moving the bracket into the heating furnace to reset the bracket;

f) heating the sample at a test temperature for 30min to convert the sample into stable ellipsoidal liquid drops, adjusting a camera to enable the ellipsoidal liquid drops to be positioned at the center of a visual image as shown in figure 1, and then shooting to obtain ellipsoidal liquid drop images;

g) the surface tension calculation system analyzes the ellipsoidal droplet image to obtain the volume V of the sample in cm at the test temperature³Then according to the mass m of the sample weighed in d), calculating to obtain the density rho of the glass meltIn units of g/cm³；

h) Inputting the density rho of the glass melt into the computing system, obtaining a surface tension value sigma through surface tension computing software, and rapidly acquiring 20 surface tension data within 10 s;

i) the remaining 4 samples were performed as in d) to h).

j) And finally, eliminating the maximum value and the minimum value of the surface tension values (sigma 1, sigma 2, sigma 3, sigma 4 and sigma 5) of the five samples, calculating the arithmetic mean value of the surface tension values of the rest three samples, and keeping an integer to be recorded as sigma.