Forming device, manufacturing facility including such forming device, and method for manufacturing glass sheet

Abstract

A molding device for forming a glass ribbon by molding molten glass, the device comprising: a device body and a plate member which is installed in a portion of said device body where contact is made at least with glass, wherein the plate member has a thickness in the range of 0.5-100 mm, and is made of a material that is inactive to said glass.

Description

[Technical field]

[0001] The present invention relates to a forming device for a production facility for glass sheets, a production facility equipped with such a forming device, and a method for producing glass sheets. [Background technology]

[0002] Glass sheets can be manufactured continuously using processes such as, for example, the fusion process and the slit downdraw process.

[0003] For example, in the fusion method, molten glass obtained by melting glass raw materials is supplied to the top of a forming device (hereinafter referred to as a "forming device"). The forming device has a cross section that is roughly wedge-shaped with a downwardly pointed edge, and the molten glass flows down along two opposing side surfaces of the forming device. The molten glass flowing down along both side surfaces joins and is integrated at a lower end (also referred to as a "junction") of the forming device, and a glass ribbon is formed. Thereafter, the glass ribbon is pulled downward by a pulling member such as a roller while being slowly cooled, and is cut to a predetermined size (for example, Patent Document 1).

[0004] In the slit downdraw method, a forming device that contains molten glass has a slit-shaped opening at the bottom. The molten glass flows down through this opening and becomes a glass ribbon. The glass ribbon is then gradually cooled and cut to produce a glass sheet. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2016-028005 A Summary of the Invention [Problem to be solved by the invention]

[0006] In a manufacturing facility for manufacturing glass sheets by the above-mentioned method or another method, from the viewpoint of improving the manufacturing efficiency of glass sheets, it is desirable for the forming device to have a configuration that can withstand rapid temperature increase and decrease. However, in order to achieve this, it is necessary to use a material that is resistant to thermal shock for the forming device.

[0007] However, such materials having thermal shock resistance are often highly reactive with glass, and it is difficult to use them as materials for forming devices. Therefore, in conventional forming devices, the heating and cooling rates cannot be increased significantly, and therefore it is difficult to improve the production efficiency of glass sheets.

[0008] The present invention has been made in view of the above background, and has an object to provide a forming device for a glass sheet manufacturing facility that allows for quicker temperature increase and decrease than conventional methods. Another object of the present invention is to provide a glass sheet manufacturing facility that includes such a forming device. Another object of the present invention is to provide a glass sheet manufacturing method that allows for quicker temperature increase and decrease than conventional methods. [Means for solving the problem]

[0009] The present invention provides a forming apparatus for forming molten glass into a glass ribbon, comprising: The main body, A plate member disposed on at least a portion of the body that contacts the glass; having The plate member has a thickness in the range of 0.5 mm to 100 mm and is made of a material that is inactive with respect to the glass.

[0010] In addition, the present invention provides a production facility for continuously producing a glass sheet, comprising: A forming device for forming the molten glass into a glass ribbon, The molding device includes: The main body, A plate member disposed on at least a portion of the body that contacts the glass; having The plate member has a thickness in the range of 0.5 mm to 100 mm and is made of a material that is inactive with respect to the glass. A manufacturing facility is provided.

[0011] Further, the present invention provides a method for producing a glass plate, comprising the steps of: forming a glass ribbon from the molten glass using a forming device; The molding device includes: The main body, A plate member disposed on at least a portion of the body that contacts the glass; having The plate member has a thickness in the range of 0.5 mm to 100 mm, and is made of a material that is inactive with respect to the glass. Effect of the Invention

[0012] The present invention can provide a forming device for a glass sheet manufacturing facility that can increase and decrease the temperature more quickly than in the past. The present invention can also provide a glass sheet manufacturing facility that includes such a forming device. Furthermore, the present invention can provide a glass sheet manufacturing method that can increase and decrease the temperature more quickly than in the past. [Brief description of the drawings]

[0013] [Figure 1] 1 is a diagram showing a schematic configuration example of a glass sheet manufacturing facility according to an embodiment of the present invention. [Diagram 2] 2 is a cross-sectional view that typically shows a cross section taken along line AA of the glass plate manufacturing equipment shown in FIG. 1. [Diagram 3] FIG. 2 is a diagram illustrating a configuration example of a glass sheet manufacturing facility according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0015] (Glass sheet manufacturing equipment according to one embodiment of the present invention) A glass sheet manufacturing equipment according to one embodiment of the present invention will be described with reference to Figs. 1 and 2.

[0016] 1 and 2 show a schematic configuration of a glass sheet manufacturing facility (hereinafter referred to as a "first manufacturing facility") 100 according to an embodiment of the present invention. In the first manufacturing facility 100, glass sheets can be continuously manufactured by the fusion method.

[0017] FIG. 2 is a schematic cross-sectional view of the first manufacturing facility 100 taken along line AA in FIG.

[0018] 1 and 2, the first manufacturing equipment 100 includes a molding device 110, a furnace 150 that houses the molding device 110, and a plurality of rollers 160 disposed below the molding device 110. Although not shown in the drawings, the first manufacturing equipment 100 further includes a cutting member below the furnace 150.

[0019] The forming apparatus 110 has a function of forming a glass ribbon GR from the molten glass MG. The forming apparatus 110 is connected to a supply pipe 105, and the molten glass MG is supplied to the forming apparatus 110 through the supply pipe 105.

[0020] The molding device 110 has a main body 120 and a plate member 130 .

[0021] The body 120 of the molding device 110 has a generally wedge-shaped cross section as shown in Fig. 2. More specifically, the body 120 has a recess 122 provided on an upper surface 121 of the body 120, a first side surface 124a and a second side surface 124b opposed to each other, and a lower end portion 129 which is an intersection of the first side surface 124a and the second side surface 124b.

[0022] The recess 122 is formed along the longitudinal direction of the main body 120, that is, along the X direction in FIGS.

[0023] The first side 124a has a first upper side 126a and a first lower side 128a. Similarly, the second side 124b has a second upper side 126b and a second lower side 128b.

[0024] The first upper side surface 126a and the second upper side surface 126b each extend in a substantially longitudinal direction (X direction) and a substantially vertical direction (Z direction) of the main body 120, and are therefore disposed substantially parallel to the XZ plane. On the other hand, the first lower side surface 128a and the second lower side surface 128b are inclined with respect to the vertical direction (Z direction) and are disposed so as to intersect with each other at a lower end portion 129 of the main body 120.

[0025] An upper portion of the first lower side surface 128a is connected to a lower portion of the first upper side surface 126a, and an upper portion of the second lower side surface 128b is connected to a lower portion of the second upper side surface 126b.

[0026] Furthermore, plate member 130 of forming device 110 is placed at least at a portion of the exposed surface of main body 120 that comes into direct contact with the glass.

[0027] For example, in the example shown in FIG. 2, the plate member 130 is arranged to cover the upper surface 121, the recess 122, the first side surface 124a (the first upper side surface 126a and the first lower side surface 128a), and the second side surface 124b (the second upper side surface 126b and the second lower side surface 128b) of the main body 120.

[0028] The molding device 110 has a shape that is substantially conformal to the shape of the main body 120. That is, the molding device 110 has an upper surface 111, a recess 112, a first side surface 114a (first upper side surface 116a and first lower side surface 118a), a second side surface 114b (second upper side surface 116b and second lower side surface 118b), and a lower end portion 119, all of which have shapes similar to the corresponding portions of the main body 120. In addition, all of these portions are formed by the exposed surface of the plate member 130.

[0029] Each roller 160 has a role of transporting the glass ribbon GR downward while adjusting the thickness of the glass ribbon GR.

[0030] When a glass sheet is manufactured using such a first manufacturing facility 100 , first, molten glass MG is supplied to a forming device 110 via a supply pipe 105 .

[0031] The molten glass MG supplied to the forming apparatus 110 is contained in the recess 112. However, when the molten glass MG is supplied in an amount exceeding the capacity of the recess 112, the molten glass MG overflows along the first side surface 114a and the second side surface 114b of the forming apparatus 110 and flows downward.

[0032] As a result, first molten glass portion 190a is formed on first upper side surface 116a of forming apparatus 110, and second molten glass portion 190b is formed on second upper side surface 116b of forming apparatus 110.

[0033] First molten glass portion 190a then flows further downward along first lower side 118a of forming apparatus 110. Similarly, second molten glass portion 190b flows further downward along second lower side 118b of forming apparatus 110.

[0034] As a result, first molten glass portion 190a and second molten glass portion 190b reach lower end 119 of forming apparatus 110 and are integrated therein. In this way, glass ribbon GR is formed.

[0035] Thereafter, the glass ribbon GR is further pulled downward in the vertical direction by the rollers 160, and is gradually cooled in the process.

[0036] Thereafter, the glass ribbon GR that has been sufficiently cooled slowly is discharged from the furnace 150 and cut to a predetermined size by cutting means (not shown).

[0037] Through the above steps, glass sheets can be produced continuously.

[0038] Here, from the viewpoint of improving the production efficiency of glass sheets, etc., it is desirable for a forming device included in a glass sheet production facility to have a configuration capable of withstanding rapid temperature increases and decreases.

[0039] However, in conventional manufacturing equipment, the main parts of the molding equipment are often made of materials such as heat-resistant bricks, and there is a risk of the main body being damaged by thermal shock when the temperature is increased or decreased rapidly. Therefore, in conventional manufacturing equipment, there is a problem that the temperature increase and decrease rates cannot be increased very much. Here, damage caused by thermal shock includes either brittle fracture, which is caused by a temperature distribution caused in a material by a sudden temperature change, or ductile deformation, which is caused by a large temperature distribution caused in a material by a sudden temperature change, or both.

[0040] In order to deal with this problem, it is conceivable to use a material that is resistant to thermal shock as the material for the body, but in general, materials with good thermal shock resistance are highly reactive with glass, making it difficult to use them for the body of the molding device.

[0041] In contrast, in first manufacturing equipment 100, the main portion of forming device 110 has main body 120 and plate member 130 having a thickness in the range of 0.5 mm to 100 mm. Moreover, plate member 130 is made of a material inactive to molten glass MG, and is placed in a location of main body 120 where it comes into contact with molten glass MG.

[0042] In the first manufacturing equipment 100 having such characteristics, the possibility that the main body 120 of the forming device 110 comes into contact with the molten glass MG during the manufacturing of the glass plate is significantly reduced because the main body 120 is protected by the plate member 130. Therefore, a material having thermal shock resistance can be selected for the main body 120.

[0043] Furthermore, the plate member 130 of the molding device 110 has a thickness in the range of 0.5 mm to 100 mm, and is characterized in that it is difficult to crack even when subjected to thermal shock.

[0044] Furthermore, in the first manufacturing facility 100, the plate member 130 is applied onto the main body 120 as a "plate," unlike a film such as a coating film.

[0045] Generally, a coating film is installed on an object to be installed in a state of being in close contact with the object to be installed. Therefore, when a coating film is installed on the body of a molding device, when the molding device is subjected to a load of rapid temperature rise and fall, the difference in thermal expansion between the body and the coating film may cause the coating film to peel off from the body, become wrinkled, or break.

[0046] However, in the case of plate member 130 installed as a plate on main body 120, strict adhesion is not required between main body 120 and plate member 130. Therefore, when plate member 130 is used, problems caused by the difference in thermal expansion with main body 120 are unlikely to occur.

[0047] Due to the above-mentioned effects, in the first manufacturing facility 100, the temperature of the forming device 110 can be increased and decreased quickly. This also makes it possible for the first manufacturing facility 100 to manufacture glass sheets more efficiently.

[0048] Furthermore, in the forming apparatus 110, the plate member 130 can be easily removed from the main body 120. Therefore, when changing the glass plate to be produced to another glass plate having a high reactivity with the plate member 130, the forming apparatus 110 of the present invention only requires replacing the plate member 130 with a plate member 130 made of a different material. Therefore, the forming apparatus 110 can produce glass plates more efficiently.

[0049] Furthermore, in conventional forming devices, if the forming device is eroded or deteriorated during the manufacture of glass sheets, the entire forming device must be replaced, which is time-consuming and costly. However, in the forming device 110, the plate member 130 can be easily removed from the main body 120, so if the plate member 130 is eroded or deteriorated during the manufacture of glass sheets, only the plate member 130 needs to be replaced. Therefore, the forming device 110 allows efficient and low-cost maintenance of the equipment during the manufacture of glass sheets.

[0050] (Each component of the molding device) Next, each of the components constituting the molding device 110 in the first manufacturing facility 100 will be described in more detail.

[0051] (Main body 120) The body 120 is constructed from a material that is resistant to thermal shock.

[0052] Specifically, the body 120 has a thermal conductivity of κ (W / mK) at room temperature and a thermal expansion coefficient of ρ (10 -6 / K), the ratio κ / ρ is 1 or greater.

[0053] Such materials have the characteristic that they are unlikely to be damaged even when they are rapidly heated from room temperature to the glass forming temperature (for example, 500° C. to 1500° C.) or rapidly cooled from the glass forming temperature to room temperature.

[0054] Examples of materials having a ratio κ / ρ of 1 or more include carbon (C) with a ratio κ / ρ of 23.5, silicon carbide (SiC) with a ratio κ / ρ of 60.0, silica sintered body with a ratio κ / ρ of 2.7, nickel (Ni) with a ratio κ / ρ of 7.3, molybdenum (Mo) with a ratio κ / ρ of 28.8, stainless steel with a ratio κ / ρ of 1.2, alumina sintered body with a ratio κ / ρ of 4.4, and mullite sintered body with a ratio κ / ρ of 1.2. The silica sintered body may contain 0.2 to 5% by weight of a component other than normal silica based on the total amount of the sintered body. The alumina sintered body may contain 0.2 to 10% by weight of a component other than normal alumina based on the total amount of the sintered body. The mullite sintered body may contain 0.5 to 5% by weight of a component other than normal mullite based on the total amount of the sintered body.

[0055] (Plate member 130) The plate member 130 is made of a material that is inactive against the glass used. For example, the material for the plate member 130 may be metal oxides such as silicon oxide, zirconium oxide, aluminum oxide, and magnesium oxide. The plate member 130 may be made of only one of these metal oxides, or may be made of two or more of these metal oxides. The plate member 130 may also contain a composite oxide of two or more metals that constitute these metal oxides. The plate member 130 may also contain a metal such as molybdenum. Specifically, the plate member 130 may be made of one or more materials selected from the group consisting of quartz, zirconia, mullite, zircon, magnesia, alumina, and molybdenum. The material that constitutes the plate member 130 preferably contains impurities of 1% by weight or less relative to the total amount of the material.

[0056] The material that is inactive to the glass varies depending on the composition of the glass used. Therefore, as the material constituting the plate member 130, a material that is low in reactivity with the glass used, i.e., an inactive material, is appropriately selected.

[0057] As described above, the thickness of the plate member 130 is in the range of 0.5 mm to 100 mm. The thickness is preferably in the range of 0.75 mm to 50 mm, and more preferably in the range of 1 mm to 30 mm.

[0058] The plate member 130 may be formed by combining a plurality of plate-like pieces having substantially the same shape or different shapes. For example, the plate member 130 may be formed by attaching a plurality of pieces for the plate member 130 to a required surface of the main body 120. Alternatively, the plate member 130 may be formed by arranging a plurality of pieces for the plate member 130 on a required surface of the main body 120 and then joining these pieces to each other.

[0059] (Another glass sheet manufacturing equipment according to one embodiment of the present invention) Next, with reference to FIG. 3, a glass sheet manufacturing equipment according to another embodiment of the present invention will be described.

[0060] 3 is a schematic diagram showing a configuration example of a glass sheet manufacturing facility (hereinafter referred to as a "second manufacturing facility") 200 according to another embodiment of the present invention. In the second manufacturing facility 200, glass sheets can be continuously manufactured by a slit downdraw method.

[0061] 3, the second manufacturing equipment 200 includes a molding device 210, a furnace 250 that houses the molding device 210, and a plurality of rollers 260 disposed below the molding device 210. Although not shown in the figure, the second manufacturing equipment 200 further includes a cutting member below the furnace 250.

[0062] The forming device 210 has a function of forming a glass ribbon GR from the molten glass MG. The forming device 210 is connected to a supply pipe (not shown), and the molten glass MG is supplied to the forming device 210 through the supply pipe.

[0063] The molding device 210 has a main body 220 and a plate member 230 .

[0064] Body 220 of molding device 210 has a "box-like" cross-sectional shape as shown in Figure 3. More specifically, body 220 has inner side surface 221, inner bottom surface 225, outer bottom surface 227, and slit 229. Slit 229 penetrates from inner bottom surface 225 to outer bottom surface 227.

[0065] Plate member 230 of forming device 210 is placed on at least a portion of the exposed surface of main body 220 that comes into direct contact with glass.

[0066] For example, in the example shown in FIG. 3, the plate member 230 is disposed so as to cover the inner side surface 221, the inner bottom surface 225, and the slits 229 of the main body 220.

[0067] The molding device 210 has a shape that is generally conformal to the shape of the main body 220. For example, the molding device 210 has an inner side surface 211, an inner bottom surface 215, and a slit 219, all of which have similar shapes to the corresponding portions of the main body 220. In addition, all of these portions are formed by the exposed surface of the plate member 230.

[0068] Although it is not clear from Fig. 3, each member of the forming device 210 extends in a direction perpendicular to the paper surface. Therefore, the forming device 210 shown in Fig. 3 has an elongated shape along the longitudinal direction (X direction).

[0069] Each roller 260 has a role of conveying the glass ribbon GR discharged from the forming device 210 downward while adjusting the thickness of the glass ribbon GR.

[0070] When a glass sheet is manufactured using such second manufacturing equipment 200, first, molten glass MG is supplied to a forming device 210 via a supply pipe (not shown).

[0071] The molten glass MG supplied to the forming apparatus 210 is first contained in the interior defined by the inner side surface 211 and the inner bottom surface 215 .

[0072] Next, the molten glass MG flows downward through the slit 219 of the forming device 210, and is cooled along the way. As a result, a glass ribbon GR is formed.

[0073] Thereafter, the glass ribbon GR is further pulled vertically downward by the rollers 260, and is gradually cooled in the process.

[0074] Thereafter, the glass ribbon GR that has been sufficiently cooled slowly is discharged from the furnace 250 and cut to a predetermined size by cutting means (not shown).

[0075] In the second production facility 200, glass sheets can be continuously produced by the above steps.

[0076] Here, in second manufacturing facility 200, the main portion of forming device 210 has main body 220 and plate member 230 having a thickness in the range of 0.5 mm to 100 mm. Moreover, plate member 230 is made of a material inactive to molten glass MG, and is placed in a location of main body 220 where it comes into contact with the glass.

[0077] In the second manufacturing equipment 200 having such characteristics, the possibility that the body 220 of the forming device 210 comes into contact with glass during the manufacturing of a glass plate is significantly reduced because the body 220 is protected by the plate member 230. Therefore, a material having thermal shock resistance can be selected for the body 220.

[0078] Furthermore, the plate member 230 of the molding device 210 has a thickness in the range of 0.5 mm to 100 mm, and is characterized in that it is difficult to crack even when subjected to thermal shock.

[0079] Furthermore, in the second manufacturing equipment 200, the plate member 230 is applied as a "plate" onto the main body 220, unlike a film such as a coating film. Therefore, defects caused by the difference in thermal expansion between the plate member 230 and the main body 220 are unlikely to occur.

[0080] Due to the above-mentioned effects, in the second production facility 200, it is possible to rapidly increase and decrease the temperature of the forming device 210. This also makes it possible for the second production facility 200 to more efficiently produce glass sheets.

[0081] Moreover, in the forming device 210, the plate member 230 can be easily removed from the main body 220. Therefore, when changing the glass plate to be produced to another glass plate having a high reactivity with the plate member 230, the forming device 210 only needs to replace the plate member 230 with a plate member 230 made of a different material. Therefore, the forming device 210 can more efficiently produce glass plates.

[0082] Furthermore, in conventional forming devices, if the forming device is eroded or deteriorated during the manufacture of glass sheets, the entire forming device must be replaced, which is very time-consuming and costly. However, in the forming device 210, the plate member 230 can be easily removed from the main body 220, so if the plate member 230 is eroded or deteriorated during the manufacture of glass sheets, only the plate member 230 needs to be replaced. Therefore, the forming device 210 allows efficient and low-cost maintenance of the equipment during the manufacture of glass sheets.

[0083] For the main body 220 and the plate member 230 of the molding device 210, the description of the main body 120 and the plate member 130 of the molding device 110 can be referred to, respectively. Therefore, no further description will be given here.

[0084] The configuration and features according to one embodiment of the present invention have been described above with reference to the molding apparatus 110 of the first manufacturing facility 100 and the molding apparatus 210 of the second manufacturing facility 200.

[0085] However, these are merely examples, and it will be apparent to a person skilled in the art having access to the present application that the glass sheet manufacturing equipment and further the forming device according to the present invention may have other configurations.

[0086] This application claims priority based on Japanese Patent Application No. 2019-238256, filed on December 27, 2019, the entire contents of which are incorporated herein by reference. [Explanation of symbols]

[0087] 100 First manufacturing facility 105 Supply pipe 110 Molding equipment 111 Top surface of molding device 112 Recess of molding device 114a: First side of molding device 114b second side of molding device 116a: first upper surface of molding device 116b second upper surface of the molding device 118a: first lower surface of molding device 118b second lower surface of the molding device 119 Lower end of molding device 120 Body 121 Top of the main body 122 Body recess 124a First side of the body 124b Second side of the body 126a: first upper surface of the body 126b second upper surface of the body 128a: first lower surface of the body 128b second lower surface of the body 129 Lower end of the body 130 Plate members 150 furnace 160 Lola 190a first molten glass portion 190b second molten glass portion 200 Second manufacturing facility 210 Molding equipment 211 Inside side of molding device 215 Inner bottom surface of molding device 219 Slits in molding equipment 220 Main Unit 221 Inner side of the main body 225 Bottom of the inside of the main body 227 External bottom surface of the main body 229 Body slit 230 Plate members 250 furnace 260 Lola GR Glass Ribbon MG Molten Glass

Claims

1. A forming apparatus for forming molten glass into a glass ribbon, comprising: The main body, A plate member disposed on at least a portion of the body that contacts the glass; having the plate member has a thickness in the range of 0.5 mm to 100 mm and is made of a material that is inactive with respect to the glass; The plate member is made of one or more materials selected from the group consisting of quartz, zirconia, mullite, zircon, and magnesia.

2. The body has a thermal conductivity of κ (W / mK) at room temperature and a thermal expansion coefficient of ρ (10 －６ 2. The molding apparatus according to claim 1, wherein the molding apparatus is made of a material having a ratio κ / ρ of 1 or greater when κ / ρ is 1 / K.

3. 3. The molding apparatus according to claim 1 or 2, wherein the body is made of one or more materials selected from the group consisting of carbon (C), silicon carbide (SiC), sintered silica, nickel (Ni), molybdenum (Mo), and stainless steel.

4. A manufacturing facility for continuously manufacturing glass sheets, comprising: A forming device for forming the molten glass into a glass ribbon, The molding device includes: The main body, A plate member disposed on at least a portion of the body that contacts the glass; having the plate member has a thickness in the range of 0.5 mm to 100 mm and is made of a material that is inactive with respect to the glass; The manufacturing facility, wherein the plate member is made of one or more materials selected from the group consisting of quartz, zirconia, mullite, zircon, and magnesia.

5. The body has a thermal conductivity of κ (W / mK) at room temperature and a thermal expansion coefficient of ρ (10 －６ 5. The manufacturing facility according to claim 4, wherein the material is made of a material having a ratio κ / ρ of 1 or more when κ / ρ is 1 / K.

6. The manufacturing equipment according to claim 4 or 5, wherein the main body is made of one or more materials selected from the group consisting of carbon (C), silicon carbide (SiC), sintered silica, nickel (Ni), molybdenum (Mo), and stainless steel.

7. A method for producing a glass sheet, comprising the steps of: forming a glass ribbon from the molten glass using a forming device; The molding device includes: The main body, A plate member disposed on at least a portion of the body that contacts the glass; having the plate member has a thickness in the range of 0.5 mm to 100 mm and is made of a material that is inactive with respect to the glass; The manufacturing method, wherein the plate member is made of one or more materials selected from the group consisting of quartz, zirconia, mullite, zircon, and magnesia.

8. The body has a thermal conductivity of κ (W / mK) at room temperature and a thermal expansion coefficient of ρ (10 －６ 8. The method according to claim 7, wherein the material is a material having a ratio κ / ρ of 1 or more when κ / ρ is 1 / K.

9. The method according to claim 7 or 8, wherein the body is made of one or more materials selected from the group consisting of carbon (C), silicon carbide (SiC), sintered silica, nickel (Ni), molybdenum (Mo), and stainless steel.

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