Chemical strengthening method for medium-high aluminosilicate glass fiber
阅读说明：本技术 一种中高铝硅酸玻璃纤维的化学强化方法 (Chemical strengthening method for medium-high aluminosilicate glass fiber ) 是由 康俊峰 陈俊竹 吴建磊 岳云龙 屈雅 侯延升 于 2021-09-28 设计创作，主要内容包括：本发明具体涉及一种中高铝硅酸玻璃纤维的化学强化方法,属于玻璃及玻璃纤维制备领域。该方法通过以下步骤实现：将熔融的中铝或高铝玻璃液经过拉制形成中铝或高铝玻璃纤维,将玻璃纤维进行预热；将预热后的玻璃纤维浸渍在熔盐中对玻璃纤维进行化学强化,然后经过冷却、清洗、烘干,最后在玻璃纤维表面涂抹浸润剂,进行封装。通过本发明提供的化学强化的中铝、高铝硅酸盐玻璃纤维具有较高的机械性能,与现有的中高铝硅酸盐玻璃纤维相比,调整了基础玻璃的组成,进一步降低了玻璃纤维的成型条件。同时,将玻璃纤维原丝进行化学强化,在玻璃纤维表面形成压应力层,改善玻璃纤维表面质量,进而提高了玻璃纤维为强度、模量等机械性能。(The invention particularly relates to a chemical strengthening method of medium and high aluminosilicate glass fibers, belonging to the field of glass and glass fiber preparation. The method is realized by the following steps: drawing the molten medium-aluminum or high-aluminum glass liquid to form medium-aluminum or high-aluminum glass fibers, and preheating the glass fibers; and (3) dipping the preheated glass fiber in molten salt to chemically strengthen the glass fiber, then cooling, cleaning and drying, and finally smearing a wetting agent on the surface of the glass fiber for packaging. The chemically strengthened medium-aluminum and high-aluminum silicate glass fiber provided by the invention has higher mechanical properties, and compared with the existing medium-aluminum and high-aluminum silicate glass fiber, the chemically strengthened medium-aluminum and high-aluminum silicate glass fiber has the advantages that the composition of basic glass is adjusted, and the forming conditions of the glass fiber are further reduced. Meanwhile, the glass fiber protofilament is chemically strengthened, a pressure stress layer is formed on the surface of the glass fiber, the surface quality of the glass fiber is improved, and the mechanical properties of the glass fiber, such as strength, modulus and the like, are improved.)
1. A chemical strengthening method of medium and high aluminosilicate glass fibers is characterized by comprising the following steps:
(1) drawing the molten medium-aluminum or high-aluminum glass liquid to form medium-aluminum or high-aluminum glass fibers, and preheating the glass fibers;
(2) and (3) dipping the preheated glass fiber in molten salt to chemically strengthen the glass fiber, then cooling, cleaning and drying, and finally smearing a wetting agent on the surface of the glass fiber for packaging.
2. The chemical strengthening method of claim 1, wherein the high-alumina glass fiber comprises the following raw materials in percentage by mass: SiO 22：58-78%，A12O3：10-24%，K2O+Na2O+Li2O：10-21%，MgO：3-12%，P2O5: 0.1-3%, clarifying agent: 0.1-3%;
the medium aluminum glass fiber comprises the following raw materials in percentage by mass: SiO 22：63%-67%；Al2O3：8%-13%；MgO：5%-7%；Na2O：14.5%-16.5%；K2O：0.5%-2.5%；ZrO2：0.3%-0.7%。
3. The chemical strengthening method according to claim 2, wherein SiO is contained in the high-alumina glass fiber2：A12O3The mass ratio of (A) to (B) is as follows: 5.5-1.5:1, SiO2：K2O+Na2O+Li2The mass ratio of O is as follows: 5.1-1.6:1, K2O+Na2O+Li2The mass percentage of O in the raw material is 12-17%, and the A12O3The mass percentage of the raw materials is 11-23%; in the medium aluminum glass fiber, Al2O3And (K)2O+Na2O) is 0.2 to 0.5.
4. The chemical strengthening method according to claim 2 or 3, wherein the glass fiber has a diameter of 30 to 100 μm.
5. The chemical strengthening method according to claim 2 or 3, wherein in the step (1), in the glass fiber preparation process:
the high aluminosilicate glass has a viscosity of 10 pas and corresponds to a temperature of: 1681-2The temperatures at Pa · s correspond to: 1397-1423 ℃ and viscosity of 103The temperatures at Pa · s correspond to: 1197 ℃ and 1231 ℃.
The viscosity of the medium aluminosilicate glass corresponds to the temperature when the viscosity is 10Pa · s: 1601 ℃ and 1625 ℃, and the viscosity is 102The temperatures at Pa · s correspond to: 1306 ℃ and 1338 ℃ and a viscosity of 103The temperatures at Pa · s correspond to: 1119-1143 ℃.
6. The chemical strengthening method as claimed in any one of claims 1 to 4, wherein the preheating temperature in step (1) is 370 ℃ and 450 ℃ and the preheating time is 0.1 to 0.8 h.
7. The chemical strengthening method according to claim 1 or 6, wherein in the step (2), the molten salt is potassium nitrate or a mixed molten salt; what is needed isThe mixed molten salt is KNO3、Al2O3And diatomite, wherein the mixed molten salt comprises the following components in percentage by mass: KNO3 90%-99%、Al2O30.1 to 4 percent of diatomite and 0.5 to 9 percent of diatomite.
8. The chemical strengthening method according to claim 7, wherein the temperature of the chemical strengthening is 370-450 ℃ and the time is 0.1-3 h.
9. The chemical strengthening method of claim 1, wherein the composition of the impregnating compound is as follows: 6 to 12 percent of polyester resin emulsion, 3 to 10 percent of epoxy resin such as liquid, 1 to 5 percent of dialdehyde starch, 0.1 to 0.8 percent of lubricant, 0.1 to 0.5 percent of defoaming agent, 0.1 to 0.6 percent of antistatic agent, 0.1 to 0.5 percent of PH value regulator and the balance of water.
Technical Field
The invention particularly relates to a chemical strengthening method of medium and high aluminosilicate glass fibers, belonging to the field of glass and glass fiber preparation.
Background
The glass fiber is an inorganic nonmetal fiber material, has excellent mechanical property, chemical stability and insulating property, and is widely applied to the fields of cement-based composite materials, phenolic resin composite materials, polymer composite materials and the like. The high-performance glass fiber is applied to the directions of aerospace, national defense and military industry, nuclear energy development and the like. For example, in the field of wind power generation of clean energy, the fan blade prepared from the glass fiber composite material can increase the length of the blade and reduce the self weight of the blade while meeting the requirements of higher strength and toughness so as to obtain more wind energy. In the automotive industry, fiberglass composites are utilized to reduce the weight of vehicles. In the engineering field, the fence and the like can be prepared by using glass fiber composite materials. With the development of composite materials, the demand of high-performance glass fibers in various industries is increasing continuously, and higher requirements are put forward on the performance of the glass fibers.
The strength of the glass fiber can be improved by introducing an oxide, and Al is added to the glass fiber raw material2O3Can improve the strength and modulus of the glass fiber, but has excessively high Al2O3The molding temperature of the glass fiber is too high, the production difficulty is high, and the cost is high. Meanwhile, in the field of thin glass product manufacturing, chemical strengthening can effectively improve the mechanical properties of glass, especially the strength and hardness properties. Relevant researches show that ions with large radius in the molten salt are replaced by ions with small radius in the glass surface through ion exchange on the glass surface, and a pressure stress layer is formed on the surface of the glass, so that the mechanical properties of the glass, such as bending resistance, impact resistance and the like, can be effectively improved. Since the strength of the glass fiber depends on the size and the number of the microcracks on the surface, researches show that the chemical strengthening can optimize the surface quality of the glass fiber, reduce the size of the microcracks on the surface of the glass fiber, and even close the microcracks with smaller sizes. Thereby the device is provided withIt can be seen that chemical strength theoretically improves the mechanical properties of the glass fibers.
The medium and high aluminosilicate glass fiber has higher tensile strength and bending strength, and the prior art is difficult to further improve the mechanical properties of the medium and high aluminosilicate glass fiber.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a chemical strengthening method of medium and high aluminosilicate glass fibers.
The technical scheme adopted by the invention for realizing the purpose is as follows:
the invention provides a chemical strengthening method of medium and high aluminosilicate glass fibers, which comprises the following steps:
(1) drawing the molten medium-aluminum or high-aluminum glass liquid to form medium-aluminum or high-aluminum glass fibers, and preheating the glass fibers;
(2) and (3) dipping the preheated glass fiber in molten salt to chemically strengthen the glass fiber, then cooling, cleaning and drying, and finally smearing a wetting agent on the surface of the glass fiber for packaging.
When the chemical strengthening is carried out, the high-alumina glass fiber comprises the following raw materials in percentage by mass: SiO 22：58-78%，A12O3：10-24%，K2O+Na2O+Li2O：10-21%，MgO：3-12%，P2O5: 0.1-3%, clarifying agent: 0.1-3%; the medium aluminum glass fiber comprises the following raw materials in percentage by mass: SiO 22：63%-67%；Al2O3：8%-13%；MgO：5%-7%；Na2O：14.5%-16.5%；K2O：0.5%-2.5%；ZrO2：0.3%-0.7%。
Further, in the high-alumina glass fiber, SiO2：A12O3The mass ratio of (A) to (B) is as follows: 5.5-1.5:1, SiO2：K2O+Na2O+Li2The mass ratio of O is as follows: 5.1-1.6:1, K2O+Na2O+Li2The mass percentage of O in the raw material is 12-17%, and the A12O3The mass percentage of the raw materials is 11-23%; the medium aluminum glassIn the glass fiber, Al2O3And (K)2O+Na2O) is 0.2 to 0.5.
The diameter of the glass fiber is 30 to 100 μm.
Further, in the step (1), during the preparation process of the glass fiber:
the high aluminosilicate glass has a viscosity of 10 pas and corresponds to a temperature of: 1681-2The temperatures at Pa · s correspond to: 1397-1423 ℃ and viscosity of 103The temperatures at Pa · s correspond to: 1197 ℃ and 1231 ℃.
The viscosity of the medium aluminosilicate glass corresponds to the temperature when the viscosity is 10Pa · s: 1601 ℃ and 1625 ℃, and the viscosity is 102The temperatures at Pa · s correspond to: 1306 ℃ and 1338 ℃ and a viscosity of 103The temperatures at Pa · s correspond to: 1119-1143 ℃.
Further, in the step (1), the preheating temperature is 370-450 ℃, and the preheating time is 0.1-0.8 h.
Further, in the step (2), the molten salt is potassium nitrate or mixed molten salt; the mixed molten salt is made of KNO3、Al2O3And diatomite, wherein the mixed molten salt comprises the following components in percentage by mass: KNO3 90%-99%、Al2O30.1 to 4 percent of diatomite and 0.5 to 9 percent of diatomite.
Furthermore, the temperature of the chemical strengthening is 370-450 ℃, and the time is 0.1-3 h.
The impregnating compound used by the invention comprises the following components: 6 to 12 percent of polyester resin emulsion, 3 to 10 percent of epoxy resin such as liquid, 1 to 5 percent of dialdehyde starch, 0.1 to 0.8 percent of lubricant, 0.1 to 0.5 percent of defoaming agent, 0.1 to 0.6 percent of antistatic agent, 0.1 to 0.5 percent of PH value regulator and the balance of water.
A1 in the raw material composition of high-alumina glass fiber2O3The content of (b) is high, the clarification of the molten glass is difficult, and the clarifying agent is added into the raw materials to promote the discharge of bubbles in the molten glass. The clarifying agent is selected from stannous oxide, cerium dioxide, sodium sulfate, antimony oxide and calcium fluoride, preferably one or more of the stannous oxide, the cerium dioxide, the sodium sulfate, the antimony oxide and the calcium fluoride; wherein the average number of visible bubbles of the glass fiber strands with the length of 10m is not more than 2. High alumina silicate glassThe temperature corresponding to the glass viscosity at 10 pas is: 1681-2The temperatures at Pa · s correspond to: 1397-1423 ℃ and viscosity of 103The temperatures at Pa · s correspond to: 1197 ℃ and 1231 ℃. The viscosity of the medium aluminosilicate glass corresponds to the temperature when the viscosity is 10Pa · s: 1601 ℃ and 1625 ℃, and the viscosity is 102The temperatures at Pa · s correspond to: 1306 ℃ and 1338 ℃ and a viscosity of 103The temperatures at Pa · s correspond to: 1119-1143 ℃. By the characteristic temperature points, the temperature of the glass fiber in the drawing process can be determined, and the drawing speed of the glass fiber can be controlled to prepare the glass fiber with the required diameter.
The chemical strengthening molten salt used by the invention is potassium nitrate or mixed molten salt, and the ionic radius of the K is larger+Na having a relatively small ionic radius+、Li+The replacement of (2) forms a pressure stress layer on the surface of the glass fiber, so that the surface quality of the glass fiber can be optimized, the size of microcracks on the surface of the glass fiber is reduced, even the microcracks with smaller closing size are reduced, and the mechanical property of the glass fiber is further improved.
Preparing high-aluminum and medium-aluminum glass fibers into precursor fibers with the diameter of 30-100 mu m, then placing the precursor fibers in mixed molten salt at 370-450 ℃, keeping the temperature for 0.1-3 h, taking out, naturally cooling to room temperature, then cleaning and drying the surfaces of the glass fibers by using deionized water, finally coating and infiltrating the surfaces of the glass fibers, and packaging. The ion exchange depth of the chemically strengthened high-alumina glass fiber with the diameter of 30-100 mu m is as follows: 8-30 μm, and the bending strength is: 1859-: 1162 and 2181MPa, the minimum curvature radius is: 2.4-6.5 mm; compared with glass fiber strands, the bending strength is improved by 32-47%, the tensile strength is improved by 26-38%, and the minimum curvature radius is reduced by 8-30%; the ion exchange depth of the chemically strengthened medium-alumina glass fiber with the diameter of 30-100 mu m is as follows: 9-30 μm, and the bending strength is: 1930-2214MPa, tensile strength: 1379-2106MPa, the minimum curvature radius is: 3.2-5.6 mm; compared with glass fiber strands, the bending strength is improved by 30-44%, the tensile strength is improved by 22-36%, and the minimum curvature radius is reduced by 9-32%
Preparing high-aluminum and medium-aluminum glass fibers into protofilament with the diameter of 5-30 mu m, then placing the glass fiber protofilament in mixed molten salt at 370-450 ℃, keeping the temperature for 0.1-3 h, taking out, naturally cooling to room temperature, then cleaning and drying the surface of the glass fiber by using deionized water, finally coating and infiltrating the surface of the glass fiber, and packaging. The ion exchange depth of the chemically strengthened high-alumina glass fiber with the diameter of 5-30 mu m is as follows: 1-10 μm, and the bending strength is: 2502-: 1997 + 2181MPa, the minimum radius of curvature is: 0.5-2.1 mm; compared with glass fiber strands, the bending strength is improved by 29-41%, the tensile strength is improved by 29-35%, and the minimum curvature radius is reduced by 7-20%; the ion exchange depth of the chemically strengthened medium-alumina glass fiber with the diameter of 5-30 mu m is as follows: 2-10 μm, and the bending strength is: 2103 and 2301MPa, and the tensile strength is as follows: 1902-2106MPa, the minimum curvature radius is: 0.9-1.3 mm; compared with glass fiber strands, the bending strength is improved by 27-40%, the tensile strength is improved by 26-37%, and the minimum curvature radius is reduced by 8-19%.
The invention aims to prepare chemically strengthened high-aluminosilicate glass fibers, wherein ions with larger radius replace ions with smaller radius on the surfaces of the glass fibers, so that a compressive stress layer is formed on the surfaces of the glass fibers, and the mechanical properties of the glass fibers are improved. The prepared chemically-reinforced high-aluminosilicate glass fiber has higher strength and modulus than the existing glass fiber, can greatly improve the mechanical property of the glass fiber composite material, has wider market and brings greater economic benefit.
The invention has the beneficial effects that:
(1) the chemically strengthened medium-aluminum and high-aluminum silicate glass fiber provided by the invention has higher mechanical properties, and compared with the existing medium-aluminum and high-aluminum silicate glass fiber, the chemically strengthened medium-aluminum and high-aluminum silicate glass fiber has the advantages that the composition of basic glass is adjusted, and the forming conditions of the glass fiber are further reduced. Meanwhile, the glass fiber protofilament is chemically strengthened, a pressure stress layer is formed on the surface of the glass fiber, the surface quality of the glass fiber is improved, and the mechanical properties of the glass fiber, such as strength, modulus and the like, are improved.
(2) The chemically strengthened high-aluminosilicate glass fiber can be widely applied to the fields of national defense and military industry, aerospace, nuclear energy development industrial equipment and the like, such as fan blades, vehicle shells, airplane radar covers, phenolic resin composite materials, bullet-proof clothes and the like.
Detailed Description
In order to better explain the chemically strengthened glass fibers of the present invention, the present invention will be described in detail with reference to several specific examples. It is to be understood that the described embodiments of the invention are merely some of the embodiments and are not to be taken as limiting the invention.
Example 1
The high-aluminosilicate glass fiber comprises the following components in percentage by mass: SiO 22The mass of the method is as follows: 60%, A12O3The mass of the method is as follows: 15% of Na2The mass of O is: 14%, K2O+Li2The mass of O is: 3 percent, and the MgO comprises the following components in percentage by mass: 5%, P2O5The mass of the method is as follows: 1.5 percent, and the mass of SnO is as follows: 1.5 percent.
The preparation method comprises the following steps:
wherein the drawing temperature of the glass fiber is 1397 ℃, the drawing speed is 25m/min, and the glass fiber with the diameter of 100 mu m is prepared.
And (3) placing the glass fiber in the mixed molten salt for chemical strengthening, wherein the strengthening temperature is 400 ℃, and the strengthening time is 1 h.
And cleaning the surface of the strengthened glass fiber to remove the molten salt residue on the surface. And then drying the glass fiber, and coating a wetting agent on the surface.
Example 2
The high-aluminosilicate glass fiber comprises the following components in percentage by mass: SiO 22The mass of the method is as follows: 62%, A12O3The mass of the method is as follows: 18% of Na2The mass of O is: 14%, K2O+Li2The mass of O is: 1 percent, and the MgO comprises the following components in percentage by mass: 3%, P2O5The mass of the method is as follows: 1% and SnO by mass: 1 percent.
The preparation method comprises the following steps:
wherein the drawing temperature of the glass fiber is 1415 ℃, the drawing speed is 149m/min, and the glass fiber with the diameter of 50 μm is prepared.
And (3) placing the glass fiber in the mixed molten salt for chemical strengthening, wherein the strengthening temperature is 390 ℃, and the strengthening time is 0.6 h.
And cleaning the surface of the strengthened glass fiber to remove the molten salt residue on the surface. And then drying the glass fiber, and coating a wetting agent on the surface.
Example 3
The high-aluminosilicate glass fiber comprises the following components in percentage by mass: SiO 22The mass of the method is as follows: 63%, A12O3The mass of the method is as follows: 17% of Na2The mass of O is: 13%, K2O+Li2The mass of O is: 1 percent, and the MgO comprises the following components in percentage by mass: 3%, P2O5The mass of the method is as follows: 1.8 percent, and the mass of SnO is as follows: 1.2 percent.
The preparation method comprises the following steps:
wherein the drawing temperature of the glass fiber is 1411 ℃, the drawing speed is 356m/min, and the glass fiber with the diameter of 25 μm is prepared.
And (3) placing the glass fiber in the mixed molten salt for chemical strengthening, wherein the strengthening temperature is 370 ℃, and the strengthening time is 0.5 h.
And cleaning the surface of the strengthened glass fiber to remove the molten salt residue on the surface. And then drying the glass fiber, and coating a wetting agent on the surface.
Example 4
The high-aluminosilicate glass fiber comprises the following components in percentage by mass: SiO 22The mass of the method is as follows: 65%, A12O3The mass of the method is as follows: 15% of Na2The mass of O is: 13%, K2O+Li2The mass of O is: 2 percent, and the MgO comprises the following components in percentage by mass: 4%, P2O5The mass of the method is as follows: 0.8 percent, and the mass of SnO is as follows: 0.2 percent.
The preparation method comprises the following steps:
wherein the drawing temperature of the glass fiber is 1403 ℃, the drawing speed is 268m/min, and the glass fiber with the diameter of 30 μm is prepared.
And (3) placing the glass fiber in the mixed molten salt for chemical strengthening, wherein the strengthening temperature is 370 ℃, and the strengthening time is 0.5 h.
And cleaning the surface of the strengthened glass fiber to remove the molten salt residue on the surface. And then drying the glass fiber, and coating a wetting agent on the surface.
Example 5
The high-aluminosilicate glass fiber comprises the following components in percentage by mass: SiO 22The mass of the method is as follows: 64%, A12O3The mass of the method is as follows: 18% of Na2The mass of O is: 12%, K2O+Li2The mass of O is: 2 percent, and the MgO comprises the following components in percentage by mass: 3%, P2O5The mass of the method is as follows: 0.7 percent, and the mass of SnO is as follows: 0.3 percent.
The preparation method comprises the following steps:
wherein the drawing temperature of the glass fiber is 1423 ℃, the drawing speed is 36m/min, and the glass fiber with the diameter of 80 μm is prepared.
And (3) placing the glass fiber in the mixed molten salt for chemical strengthening, wherein the strengthening temperature is 390 ℃, and the strengthening time is 1 h.
And cleaning the surface of the strengthened glass fiber to remove the molten salt residue on the surface. And then drying the glass fiber, and coating a wetting agent on the surface.
The chemically strengthened high-alumina glass fibers obtained in examples 1 to 5 were subjected to performance testing by a conventional testing method in the art, and the specific results are shown in table 1.
TABLE 1
Example 6
The medium aluminosilicate glass fiber comprises the following components in percentage by mass: SiO 22：63%；Al2O3：12.5%；MgO：7%；Na2O：15.5%；K2O：1.5%；ZrO2：0.5%。。
The preparation method comprises the following steps:
wherein the drawing temperature of the glass fiber is 1338 ℃, the drawing speed is 275m/min, and the glass fiber with the diameter of 30 μm is prepared.
And (3) placing the glass fiber in the mixed molten salt for chemical strengthening, wherein the strengthening temperature is 390 ℃, and the strengthening time is 0.6 h.
And cleaning the surface of the strengthened glass fiber to remove the molten salt residue on the surface. And then drying the glass fiber, and coating a wetting agent on the surface.
Example 7
The medium aluminosilicate glass fiber comprises the following components in percentage by mass: SiO 22：66%；Al2O3：11%；MgO：6%；Na2O：14.5%；K2O：2%；ZrO2：0.5%。。
The preparation method comprises the following steps:
wherein the drawing temperature of the glass fiber is 1330 ℃, the drawing speed is 42m/min, and the glass fiber with the diameter of 80 μm is prepared.
And (3) placing the glass fiber in the mixed molten salt for chemical strengthening, wherein the strengthening temperature is 410 ℃, and the strengthening time is 1 h.
And cleaning the surface of the strengthened glass fiber to remove the molten salt residue on the surface. And then drying the glass fiber, and coating a wetting agent on the surface.
Example 8
The medium aluminosilicate glass fiber comprises the following components in percentage by mass: SiO 22：65.6%；Al2O3：10%；MgO：8%；Na2O：15%；K2O：1%；ZrO2：0.4%。
The preparation method comprises the following steps:
wherein the drawing temperature of the glass fiber is 1325 ℃, the drawing speed is 363m/min, and the glass fiber with the diameter of 25 μm is prepared.
And (3) placing the glass fiber in the mixed molten salt for chemical strengthening, wherein the strengthening temperature is 370 ℃, and the strengthening time is 0.5 h.
And cleaning the surface of the strengthened glass fiber to remove the molten salt residue on the surface. And then drying the glass fiber, and coating a wetting agent on the surface.
Example 9
The medium aluminosilicate glass fiber comprises the following components in percentage by mass: SiO 22：67%；Al2O3：8%；MgO：6.5%；Na2O：16.5%；K2O：1.4%；ZrO2：0.6%。
The preparation method comprises the following steps:
wherein the drawing temperature of the glass fiber is 1306 ℃, the drawing speed is 152m/min, and the glass fiber with the diameter of 50 μm is prepared.
And (3) placing the glass fiber in the mixed molten salt for chemical strengthening, wherein the strengthening temperature is 370 ℃, and the strengthening time is 1 h.
And cleaning the surface of the strengthened glass fiber to remove the molten salt residue on the surface. And then drying the glass fiber, and coating a wetting agent on the surface.
The performance of the chemically strengthened medium-alumina glass fibers of examples 6 to 9 was tested by a conventional testing method in the art, and the specific results are shown in table 2.
TABLE 2
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