JP2015105196A - Manufacturing method for glass substrate and manufacturing apparatus for glass substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for a glass substrate and a manufacturing apparatus for a glass substrate that prevent a flange from being broken owing to platinum vaporization.SOLUTION: There is provided a manufacturing method for a glass substrate that includes a process of molding a glass substrate out of molten glass. The manufacturing method includes: a transport pipe 10 which transports molten glass; a pair of platinum-based flanges 11 which are provided for the transport pipe 10, and formed of platinum or platinum alloy for heating the transport pipe 10; and electrodes 12 which are provided for the platinum-based flanges 11, and heat the platinum-based flanges 11 by electrification. At least parts of the platinum-based flanges 11 are coated with refractory ceramic by spraying so as to form spray coating films 14. The refractory ceramic has a higher fusion point than the platinum or platinum alloy. The spray coating films may be formed of a material selected from the group of Al, Be, Cr, Co, Cu, Au, Mo, Ni, Nb, Pd, Ag, Ti, Zr, or alloy thereof instead of the refractory ceramic.

Description

  The present invention relates to a glass substrate manufacturing method and a glass substrate manufacturing apparatus.

  Conventionally, a glass substrate is manufactured by transferring molten glass obtained by melting glass raw materials to a forming furnace. The transfer tube for transferring the molten glass needs to heat the molten glass in the tube to a predetermined temperature, and in order to efficiently perform this heating, a heating device is provided in the transfer tube. Patent Document 1 discloses a molten glass heating device that uses a transfer tube made of platinum or a platinum alloy, and that is provided with a platinum flange electrode for energization, and that energizes and heats the transfer tube. When the temperature of the molten glass is raised to, for example, several thousand hundred degrees, the platinum flange electrode is also heated, and the platinum flange electrode volatilizes, whereby the platinum flange electrode may be damaged.

JP-A-11-349334

  Then, an object of this invention is to provide the manufacturing method of the glass substrate which prevents the damage of the flange by platinum volatilization, and the manufacturing apparatus of a glass substrate.

One aspect of the present invention is a method for producing a glass substrate including a step of forming a glass substrate from molten glass,
A transfer pipe for transferring the molten glass;
At least a pair of platinum-based flanges provided in the transfer pipe and formed of platinum or a platinum alloy for heating the transfer pipe;
An electrode that is provided on the platinum-based flange and that electrically heats the platinum-based flange;
A refractory ceramic is sprayed on at least a part of the platinum-based flange to form a sprayed film.
It is characterized by that.

  The melting point of the refractory ceramic is preferably higher than that of platinum or a platinum alloy.

  The sprayed film is formed from the group consisting of aluminum, beryllium, chromium, cobalt, copper, gold, molybdenum, nickel, niobium, palladium, silver, titanium, zirconium, and alloys thereof instead of the refractory ceramic. May be.

The transfer tube is formed of platinum or a platinum alloy, heated to a temperature at which the molten glass is clarified, and thermally expanded.
The platinum-based flange is pressed into contact with the platinum-based flange of another transfer pipe by the stress due to the thermal expansion,
The sprayed film may be formed at a position where it is pressed against a platinum-based flange included in the other transfer pipe.

One embodiment of the present invention is a glass substrate manufacturing apparatus for manufacturing a glass substrate from molten glass,
A transfer pipe for transferring the molten glass;
At least a pair of platinum-based flanges provided in the transfer pipe and formed of platinum or a platinum alloy for heating the transfer pipe;
An electrode that is provided on the platinum-based flange and that electrically heats the platinum-based flange;
A refractory ceramic is sprayed on at least a part of the platinum-based flange to form a sprayed film.
It is characterized by that.

  According to the said aspect, the failure | damage of the flange by platinum volatilization can be prevented.

It is a figure which shows typically an example of the apparatus used for the manufacturing method of the glass substrate concerning this embodiment. It is a figure which shows the transfer pipe which concerns on this embodiment. (A) is a front view of a transfer pipe, (b) is sectional drawing of the AA line of (a).

(Embodiment 1)
Hereinafter, with reference to drawings, the manufacturing method of the glass substrate concerning this embodiment is explained.
The manufacturing method of a glass plate mainly has a melting process, a clarification process, a homogenization process, a supply process, a shaping | molding process, a slow cooling process, and a cutting process. FIG. 1 is a diagram schematically showing an apparatus for performing a melting process to a cutting process. The apparatus mainly includes a melting apparatus 100, a forming apparatus 200, and a cutting apparatus 300, as shown in FIG. The melting apparatus 100 includes a melting tank 101, a clarification tank 102, a stirring tank 103, and glass supply pipes 104, 105, and 106.

In the melting step, molten glass is obtained by heating and melting the glass raw material supplied into the melting tank 101 with a flame and an electric heater (not shown).
The clarification step is mainly performed in the clarification tank 102 and the glass supply pipe 105 including the glass supply pipe 104, the glass supply pipe having a pair of platinum-based flanges and electrodes, and by heating the molten glass MG in the clarification tank 102. , Bubbles such as O ₂ contained in the molten glass MG grow by the oxidation-reduction reaction of the clarifying agent and float on the liquid surface, or the gas components in the bubbles are absorbed into the molten glass, Bubbles disappear.
In the homogenization step, the glass components are homogenized by stirring the molten glass MG in the stirring tank 103 supplied through the glass supply pipe 105 using a stirrer.
In the supply step, molten glass MG is supplied to the forming apparatus 200 through the glass supply pipe 106.

In the molding apparatus 200, a molding process and a slow cooling process are performed. In the forming step, the molten glass MG is formed into a sheet glass G, and a flow of the sheet glass G is created. In the slow cooling process, the sheet-like glass G that is molded and flows is cooled to have a desired thickness and no internal distortion occurs.
In the cutting step, the cutting device 300 cuts the sheet glass G supplied from the forming device 200 into a predetermined length, thereby obtaining a plate-like glass plate. The cut glass plate is further cut into a predetermined size to produce a target size glass plate. After this, the glass end surface is ground, polished, and the glass main surface is cleaned, and after checking for abnormal defects such as bubbles and striae, the glass plate that has passed the inspection is packed as the final product. The

As a transfer pipe for transferring the molten glass used in the method for manufacturing a glass substrate according to this embodiment, there are a glass supply pipe 104, 105, 106, and a clarification tank 102 provided with the glass supply pipe. Below, the glass supply pipe | tube with which the clarification tank 102 is provided is demonstrated as the transfer pipe | tube 10. FIG. In the transfer tube 10, the molten glass flowing in the transfer tube 10 is, for example, 1600 ° C. in order to grow bubbles such as O ₂ contained in the molten glass MG by the oxidation-reduction reaction of the clarifying agent and to float on the liquid surface. It is necessary to heat to about ~ 1700 ° C. Since the flange 11 (described later) included in the transfer pipe 10 may be damaged due to platinum volatilization due to heating, it is necessary to prevent platinum volatilization of the flange 11.

  FIG. 2 is a view showing a transfer pipe according to the present embodiment. 3A is a front view of the transfer tube 10, and FIG. 3B is a cross-sectional view taken along line AA in FIG. The clarification tank 102 is for transferring the molten glass while heating, from a transfer pipe 10 through which the molten glass flows, a pair of flanges 11 provided at both ends of the transfer pipe 10, and the flange 11. A pair of electrodes 12 drawn in the same direction, a flange 11 and a cooling pipe 13 for cooling the electrode 12 are provided.

  The transfer tube 10 is made of platinum or a platinum alloy and has a substantially cylindrical shape. When a voltage is applied between the electrodes 12 to be described later, the transfer tube 10 is energized and heated by causing a current to flow through the transfer tube 10 and the flange 11 between the electrodes 12. By this energization heating, the molten glass flowing through the transfer tube 10 is heated to about 1600 ° C. to 1700 ° C., for example.

  The flange 11 is made of platinum or a platinum alloy, has a flange shape that is welded to the outer peripheral surfaces at both ends of the transfer tube 10, and supplies current to the transfer tube 10 to heat the transfer tube 10 by energization. As a result, the molten glass is heated to perform defoaming treatment for releasing bubbles into the gas phase space, and the temperature of the molten glass is maintained at a clear and appropriate temperature. Further, the transfer pipe 10 is fixed by contacting the flange 11 with another adjacent transfer pipe made of platinum or a platinum alloy. If the flange 11 composed of fixed platinum or a platinum alloy keeps in contact with the pressure applied at a high temperature, the flange 11 may cause diffusion bonding. Below, in order to make description easy, the case where the other transfer pipe 10 which has the same structure as the transfer pipe 10 and the transfer pipe 10 contact | abut is demonstrated. In addition, the pipe | tube contact | abutted to the transfer pipe 10 is not limited to the same transfer pipe as the transfer pipe 10, The glass supply pipes 104, 105, 106 comprised with platinum or a platinum alloy, The melting tank 101 which melt | dissolves a glass raw material The stirring tank 103 for stirring the molten glass, the forming apparatus 200 for forming the sheet glass, and the like are optional.

  The electrode 12 is welded and extended to the flange 11 and is connected to a power supply device (not shown). The electrode 12 causes the current flowing from the power supply device to flow through the flange 11 and causes the flange 11 and the transfer tube 10 to generate heat. In order to clarify the molten glass, the transfer tube 10 through which the molten glass flows is heated, and the heated transfer tube 10 expands in the flow direction of the molten glass. Since the transfer pipe 10 is fixed between the other transfer pipes 10, the transfer pipe 10 receives a compressive stress from the other transfer pipes 10. The tube 10 is distorted, bent and causes damage.

  The cooling pipe 13 is formed in a tubular shape and is provided so as to contact the periphery of the flange 11 and the electrode 12. The cooling pipe 13 has an inlet for receiving a refrigerant (for example, a liquid such as water) supplied from a refrigerant supply device (not shown), and an outlet for discharging the supplied refrigerant to the refrigerant supply device. And by letting a refrigerant pass, overheating of flange 11 and electrode 12 is controlled, and breakage of flange 11 and electrode 12 is prevented.

The sprayed film 14 is a film formed by spraying at least a part of the flange 11 with a material belonging to the group consisting of refractory ceramics, that is, glass, semi-crystallized glass, and crystalline ceramic. The refractory ceramic has a high refractory property due to a melting point exceeding 1800 ° C., for example. Since the melting point of platinum is 1768 ° C., it is possible to prevent volatilization of the flange 11 made of platinum by spraying a refractory ceramic having a melting point higher than this melting point on the flange 11.
The sprayed film 14 may be a film formed by spraying a metal material that suppresses diffusion bonding with platinum, that is, a metal material other than platinum or a platinum alloy, instead of the refractory ceramic. In order to suppress diffusion bonding, the sprayed film 14 is formed on the flange 11 of the transfer pipe 10 that abuts (opposes) the flange 11 of another transfer pipe 10. Specifically, the sprayed film 14 is made of a material made of a group consisting of aluminum, beryllium, chromium, cobalt, copper, gold, molybdenum, nickel, niobium, palladium, silver, titanium, zirconium, ceramic, and alloys thereof. Formed by thermal spraying. Since these substances are substances having a high melting point, heat resistance, erosion resistance, high strength, and no carbon atoms, they are suitable for protecting platinum for a long period of time at a high temperature at which molten glass is clarified. More preferably, the substance consisting of these groups is a substance having low thermal conductivity, low electrical conductivity, and insulation, such as zirconium, zirconium alloy, zirconia (zirconium dioxide), stabilized zirconia (CaO stabilized zirconia, Y _2). O ₃ stabilized zirconia) and / or ceramic materials (including Al ₂ O ₃ , ZrO ₂ , Cr ₂ O ₃ , TiO ₂ , MgO). Since a current flows through the flange 11, by spraying an insulating material, leakage current leaking from the flange 11 can be suppressed, and the refractory support that supports the transfer pipe 10 from the outer periphery can be protected.

  Examples of the thermal spraying method include gas spraying (for example, flame spraying) and electric spraying (for example, atmospheric plasma spraying, reduced pressure plasma spraying). In the thermal spraying, since the deposition rate of the sprayed film 14 is high, and there are many kinds of materials that can be sprayed, substances of the above-described group can be used. Further, after a masking tape or the like is previously attached to a portion where the sprayed film 14 is not formed (for example, inside the transfer tube 10 through which the molten glass flows), it can be sprayed onto the contact surface of the flange 11. Further, by masking an arbitrary position on the contact surface of the flange 11, a part of the flange 11 can be sprayed. Further, thermal spraying can be performed on a surface facing the contact surface of the flange 11. The thickness of the sprayed film 14 is, for example, 0.1 mm to 5 mm, and can be appropriately changed depending on the material to be sprayed.

  Here, the diffusion bonding of platinum will be described. First, diffusion bonding is a method in which a base material is brought into close contact, and pressure is applied to the extent that plastic deformation does not occur as much as possible under a temperature condition equal to or lower than the melting point of the base material. Say. Even if it is metal materials, if it is made to contact and heats, metals will mix and will be joined. The movement of atoms occurring between the bonding surfaces varies depending on the crystal structure, but diffusion becomes easier as the temperature increases. Diffusion bonding has high bonding strength compared to bonding such as welding because metal atoms are closely bonded in atomic order. In addition, the same metals have the same atomic arrangement and are easy to approach in an atomic order, so that diffusion bonding is easy. For this reason, it is difficult to separate the diffusion bonded metals.

  The transfer tube 10 made of platinum or a platinum alloy is heated to a temperature (for example, about 1600 ° C. to 1700 ° C.) at which the molten glass containing tin oxide as a clarifier is clarified. Although the heated transfer pipe 10 expands in the longitudinal direction of the pipe due to thermal expansion, the flange 11 of the transfer pipe 10 is fixed to another transfer pipe 10 because it is sandwiched and fixed between other transfer pipes 10 adjacent to each other. Compressive stress is received from the flange 11. When the state in which the flange 11 of the transfer pipe 10 and the flange 11 of the other transfer pipe 10 are in pressure contact continues for a long time under a high temperature condition of platinum melting point of 1768 ° C. or less, platinum atoms move on the pressure contact surface of the flange 11 and platinum They are mixed and diffusion bonded. Since a stronger force is needed to peel off the diffusion bonded flange 11 having a high bonding strength, it takes time and labor to replace the transfer pipe 10. Since the sheet glass and the glass substrate cannot be manufactured while the transfer tube 10 is exchanged, the yield deteriorates. For this reason, a transfer tube that does not undergo diffusion bonding and can be easily replaced is required.

  In the flange 11 in which the sprayed film 14 is sprayed on the contact surface, the sprayed film 14 functions as a protective film, and the flanges 11 made of platinum or a platinum alloy do not contact each other. The sprayed film 14 is formed of a material having an atomic arrangement different from that of platinum, and since the atomic arrangement at the bonding interface does not match each other, atoms are difficult to approach and diffusion bonding is suppressed. The bonding strength between the two is lower than the bonding strength between platinum. For this reason, it becomes easy to peel off the flange 11, and the time for exchanging the transfer pipe 10 can be shortened. In addition, since the sprayed film 14 formed by spraying a material having a high melting point on the flange 11 made of platinum or a platinum alloy prevents volatilization of platinum, the transfer tube 10 can be used for a long period of time.

  If it is the transfer pipe 10 demonstrated above, since volatilization of platinum can be prevented, damage to the flange 11 can be suppressed over a long period of time, and the transfer pipe 10 can be used for a long period of time. Further, since the transfer tube 10 can suppress and prevent diffusion bonding, the transfer tube 10 can be easily replaced in a short time even when the transfer tube 10 is damaged.

(Embodiment 2)
Next, the case where the flange 11 contains a metal substance other than platinum or a platinum alloy will be described. In addition, description is abbreviate | omitted about the structure which is common in the above-mentioned embodiment.

  When the flange 11 is configured to include a metal material other than platinum or a platinum alloy, for example, palladium, silver, or copper, the sprayed film 14 is a material excluding the material that configures the flange 11 (here, platinum, palladium, Substances other than silver and copper) are formed by thermal spraying. When the same material is pressed together under high temperature conditions, diffusion bonding is facilitated. Therefore, by spraying a material excluding the material constituting the flange 11 to form the sprayed film 14, diffusion bonding is suppressed and prevented and transferred. Even if the tube 10 is damaged, the transfer tube 10 can be easily replaced in a short time. Further, since the sprayed film 14 formed of a material having a high melting point, excluding the material constituting the flange 11, can prevent the material constituting the flange 11 from volatilizing, the flange 11 is damaged. Can be suppressed over a long period of time, and the transfer tube 10 can be used for a long period of time.

10 Transfer pipe 11 Flange 12 Electrode 13 Cooling pipe 14 Sprayed film

Claims (5)

A method for producing a glass substrate comprising a step of forming a glass substrate from molten glass,
A transfer pipe for transferring the molten glass;
At least a pair of platinum-based flanges provided in the transfer pipe and formed of platinum or a platinum alloy for heating the transfer pipe;
An electrode that is provided on the platinum-based flange and that electrically heats the platinum-based flange;
A refractory ceramic is sprayed on at least a part of the platinum-based flange to form a sprayed film.
A method for producing a glass substrate, comprising: The melting point of the refractory ceramic is higher than the melting point of platinum or platinum alloy,
The method for producing a glass substrate according to claim 1. The sprayed film is formed from the group consisting of aluminum, beryllium, chromium, cobalt, copper, gold, molybdenum, nickel, niobium, palladium, silver, titanium, zirconium, and alloys thereof instead of the refractory ceramic. The
The manufacturing method of the glass substrate of Claim 1 or 2 characterized by the above-mentioned. The transfer tube is formed of platinum or a platinum alloy, heated to a temperature at which the molten glass is clarified, and thermally expanded.
The platinum-based flange is pressed into contact with the platinum-based flange of another transfer pipe by the stress due to the thermal expansion,
The sprayed film is formed at a position pressed against a platinum-based flange of the other transfer pipe.
The manufacturing method of the glass substrate of Claim 3 characterized by the above-mentioned. A glass substrate manufacturing apparatus for manufacturing a glass substrate from molten glass,
A transfer pipe for transferring the molten glass;
At least a pair of platinum-based flanges provided in the transfer pipe and formed of platinum or a platinum alloy for heating the transfer pipe;
An electrode that is provided on the platinum-based flange and that electrically heats the platinum-based flange;
A refractory ceramic is sprayed on at least a part of the platinum-based flange to form a sprayed film.
An apparatus for producing a glass substrate.

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