Platinum-coated refractory, tube glass manufacturing apparatus, and method for manufacturing platinum-coated refractory

Abstract

To provide a platinum coating refractory capable of improving adhesion strength between a refractory base material and a platinum coating, a tube glass manufacturing device and a manufacturing method of the platinum coating refractory.SOLUTION: An upper wall 43 of a muffle furnace 40 comprises an upper wall body 431 as a refractory base material having ceramic particles as an aggregate and a platinum coating 432 which is a sprayed film covering the upper wall body 431. In lower surfaces 43a and 43b of the upper wall body 431 covered by the platinum covering, a ratio occupied by the aggregate having a particle size equal to or greater than 800 μm is equal to or less than 10% in a particle size distribution of reference area per unit area.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a platinum-coated refractory, a glass tube manufacturing apparatus, and a method for manufacturing a platinum-coated refractory. [Background technology]

[0002] Patent Document 1 describes a platinum-coated refractory used in glass product manufacturing equipment, glass melting furnaces, etc. This platinum-coated refractory includes a refractory substrate and a platinum coating formed by thermally spraying platinum onto the surface of the refractory substrate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2003-13195 A Summary of the Invention [Problem to be solved by the invention]

[0004] In such platinum-coated refractories, it is desirable to further increase the adhesive strength between the refractory substrate and the platinum coating so that the platinum coating does not peel off from the refractory substrate. [Means for solving the problem]

[0005] The means for solving the above problems and their effects will be described below. The platinum-coated refractory that solves the above-mentioned problems is a platinum-coated refractory comprising a refractory base material having ceramic particles as aggregates, and a platinum coating which is a thermal sprayed film coating the refractory base material, and when the surface of the refractory base material coated with the platinum coating is defined as a coated surface, the coated surface has an area-based particle size distribution per unit area in which the proportion of aggregates having a particle size of 800 μm or more is 10% or less.

[0006] The platinum-coated refractory having the above-mentioned configuration has a rough coated surface because aggregates with large particle diameters are unlikely to appear on the coated surface. As a result, an anchor effect between the coated surface and the platinum coating is easily obtained. Therefore, the platinum-coated refractory having the above-mentioned configuration can increase the adhesive strength between the refractory substrate and the platinum coating.

[0007] The maximum height, which is an index of the surface roughness of the coated surface, is preferably 200 μm or more and less than 400 μm. According to the above-mentioned configuration, the adhesive strength between the refractory substrate and the platinum coating can be further increased.

[0008] The adhesion strength between the refractory substrate and the platinum coating is preferably 10 MPa or more. A tubular glass manufacturing apparatus that solves the above problem includes a muffle furnace and a sleeve placed inside the muffle furnace, and produces tubular glass by drawing out molten glass supplied to the sleeve from the tip of the sleeve, and uses any of the platinum-coated refractories described above as a refractory material constituting the upper wall of the muffle furnace.

[0009] In the tube glass manufacturing apparatus, the above-mentioned function and effect of the platinum-coated refractory can be obtained. A method for producing a platinum-coated refractory that solves the above-mentioned problems is a method for producing a platinum-coated refractory comprising a refractory substrate having ceramic particles as aggregates and a platinum coating coating the refractory substrate, the method comprising: a surface treatment step of roughening a coating surface of the refractory substrate, the coating surface having a ratio of aggregates having a particle diameter of 800 μm or more in an area-based particle diameter distribution per unit area of ​​10% or less; and a coating formation step of spraying platinum or a platinum alloy onto the coating surface, the surface treatment step being a step of blasting the coating surface.

[0010] In the method for producing a platinum-coated refractory, the above-mentioned function and effect of the platinum-coated refractory can be obtained. In addition, when a coated surface having a large amount of small-particle-sized aggregate is subjected to a blasting treatment, the small-particle-sized aggregate is removed from the coated surface, and a more complex uneven shape is easily formed on the coated surface. In this way, the method for producing a platinum-coated refractory can further enhance the anchor effect between the refractory substrate and the platinum coating. Effect of the Invention

[0011] The platinum-coated refractory, the glass tube manufacturing apparatus, and the method for manufacturing the platinum-coated refractory can increase the adhesive strength between the refractory substrate and the platinum coating. [Brief description of the drawings]

[0012] [Figure 1] FIG. [Diagram 2] FIG. 2 is a cross-sectional view taken along line 2-2 in FIG. [Diagram 3] 1 is an image showing the surface of a refractory substrate according to an embodiment. [Figure 4] 1 is an image showing the surface of a refractory substrate of a comparative example. [Diagram 5] 1 is a table showing the area distribution of particle sizes in Examples and Comparative Examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of a glass tube manufacturing apparatus will be described with reference to the drawings. The glass tube manufacturing apparatus of this embodiment is a Danner type glass tube manufacturing apparatus. In the drawings, some components are omitted or exaggerated in order to facilitate understanding of the description.

[0014] <Glass tube manufacturing equipment 10> As shown in Figures 1 and 2, a tubular glass manufacturing apparatus 10 includes a supply section 20 that supplies molten glass to a sleeve 31 which is a forming body, a forming section 30 that supplies the molten glass to the sleeve 31 and forms it into tubular glass, and a muffle furnace 40 that houses the forming section 30.

[0015] The forming unit 30 has a cylindrical sleeve 31 and a support shaft 32 that supports the base end of the sleeve 31. The sleeve 31 is made of a refractory material. The tip end of the sleeve 31 has an outer diameter that decreases toward the tip. In other words, the tip end of the sleeve 31 is tapered. On the other hand, the portion of the sleeve 31 other than the tip end has an outer diameter that is approximately constant in the axial direction. The support shaft 32 supports the base end of the sleeve 31 so that the axis of the sleeve 31 is inclined relative to the horizontal direction. In detail, the support shaft 32 supports the sleeve 31 so that the tip end of the sleeve 31 is located lower than the base end of the sleeve 31. When the support shaft 32 rotates, the sleeve 31 rotates together with the support shaft 32. When forming the molten glass into a tubular glass, the forming unit 30 rotates the sleeve 31 to stretch the molten glass supplied to the sleeve 31. The molten glass stretched in the sleeve 31 is drawn out from the tip of the sleeve 31. At this time, the forming unit 30 discharges gas from the tip of the sleeve 31 to form the glass tube.

[0016] The muffle furnace 40 has a rectangular box shape. The muffle furnace 40 has a bottom wall 41 constituting the bottom, a side wall 42 extending from the bottom wall 41, an upper wall 43 constituting the upper part, a partition wall 44 that divides the inside of the muffle furnace 40, a support wall 45 that supports the partition wall 44, and a heat source 46. The muffle furnace 40 has a forming chamber 47 in which the sleeve 31 is disposed, and a heating chamber 48 in which the heat source 46 is disposed.

[0017] The walls constituting the muffle furnace 40 are made of a single refractory material. The walls constituting the muffle furnace 40 may be made by combining a plurality of refractories. Examples of the refractory material include oxide refractories such as alumina zircon refractories, mullite refractories, and alumina refractories, and non-oxide refractories such as silicon carbide refractories, aluminum nitride refractories, and silicon nitride refractories.

[0018] The side wall 42 has a first side wall 421, a second side wall 422, a third side wall 423, and a fourth side wall 424 extending upward from the bottom wall 41. The first side wall 421 and the second side wall 422 face each other, and the third side wall 423 and the fourth side wall 424 face each other.

[0019] The first side wall 421 is one of two wall portions located on an extension of the rotation axis of the sleeve 31, and is located on the base end side of the sleeve 31. The first side wall 421 has a first through hole 42a penetrating in the plate thickness direction. The support shaft 32 of the forming part 30 is inserted into the first through hole 42a. The second side wall 422 is one of two wall portions located in the extension direction of the rotation axis of the sleeve 31, and is located on the tip side of the sleeve 31. The second side wall 422 has a second through hole 42b penetrating in the plate thickness direction. The molten glass drawn from the sleeve 31 passes through the second through hole 42b.

[0020] The upper wall 43 constitutes a ceiling portion of the muffle furnace 40. The upper wall 43 has an upper wall main body 431 and a platinum coating 432 that covers the upper wall main body 431. The upper wall main body 431 has a first lower surface 43a connected to the third side wall 423, a second lower surface 43b connected to the fourth side wall 424, and a supply port 43c through which the molten glass supplied from the supply unit 20 passes.

[0021] The first lower surface 43a and the second lower surface 43b face the forming chamber 47. As shown in FIG. 2, the first lower surface 43a is inclined downward as it approaches the third side wall 423, and the second lower surface 43b is inclined downward as it approaches the fourth side wall 424. In the first lower surface 43a and the second lower surface 43b, the portion where the two are connected, in other words, the portion located above the sleeve 31, is located at the uppermost position among the first lower surface 43a and the second lower surface 43b. The supply port 43c is located above the sleeve 31. Therefore, the molten glass flowing down from the supply unit 20 is supplied onto the sleeve 31.

[0022] The platinum coating 432 is a sprayed film of platinum or a platinum alloy. As the platinum alloy, a platinum-rhodium alloy is preferable, and a platinum-10% rhodium alloy is more preferable. Although the platinum-rhodium alloy is more expensive than platinum, it has high mechanical strength at high temperatures and is therefore suitable for use when mechanical strength is required. The platinum alloy may contain gold, iridium, or other metals. The thickness of the sprayed film is, for example, 200 μm to 400 μm.

[0023] The partition wall 44 divides the inside of the muffle furnace 40 into a molding chamber 47 and a heating chamber 48. The partition wall 44 may have any shape as long as it can divide the molding chamber 47. In this embodiment, the partition wall 44 is U-shaped in the front view shown in FIG. 2 and extends in the axial direction of the sleeve 31. The upper end of the partition wall 44 is connected to the upper wall 43, and both ends in the extending direction of the partition wall 44 are connected to the first side wall 421 and the second side wall 422, respectively. The molding chamber 47 is connected to the outside via the first through hole 42a, the second through hole 42b, and the supply port 43c. On the other hand, the heating chamber 48 is a closed space that is not connected to the molding chamber 47. The heat source 46 is, for example, a burner and an electric heater.

[0024] <Production method of platinum-coated refractories> Next, a method for manufacturing the platinum-coated refractory such as the upper wall 43 will be described. The method for producing a platinum-coated refractory includes a refractory production step of producing a refractory substrate, a surface treatment step of roughening the surface of the refractory substrate, and a coating step of forming a platinum coating 432 on the surface of the refractory substrate. Here, the refractory substrate corresponds to the upper wall body 431 and the like in the tubular glass manufacturing apparatus 10.

[0025] The refractory manufacturing process is a process for manufacturing a refractory base material by so-called slip casting. More specifically, the refractory manufacturing process includes a dispersion process in which ceramic particles, which are aggregates of the refractory base material, are dispersed in a solvent to form a slurry, a molding process in which the slurry poured into a mold is solidified, and a firing process in which the solidified product obtained by the molding process is fired. The aggregate dispersed in the solvent in the dispersion process preferably has a particle diameter of less than 150 μm when the cumulative frequency is 50% in a volume-based particle diameter distribution, and preferably has a particle diameter of less than 400 μm when the cumulative frequency is 90%. According to this, in the refractory base material, the surface to be coated with the platinum coating 432 (hereinafter also referred to as the "coated surface") has a ratio of aggregates having a particle diameter of 1.1 mm or more in an area-based particle diameter distribution that is 10% or less. When the platinum-coated refractory is the upper wall 43, the coated surface corresponds to the first lower surface 43a and the second lower surface 43b. The aggregate may be of one type or of multiple types. The type of aggregate can be appropriately selected depending on the type of refractory material, so long as the particle size is within the above range.

[0026] The surface treatment step is a step of blasting ceramic particles such as alumina onto the coating surface of the refractory substrate. The diameter of the particles blasted onto the coating surface is preferably equal to the particle diameter of the aggregate of the refractory substrate. When particles of the above particle diameter are used in the surface treatment step, the aggregate present on the coating surface of the refractory substrate is more likely to fall off from the coating surface. Then, the falling off of the aggregate forms recesses, and the surface area of ​​the coating surface of the refractory substrate is increased.

[0027] After the surface treatment process is performed, aggregates with small particle diameters fall off from the coated surface of the refractory substrate, so that the particle diameter distribution on the coated surface changes. In detail, after the surface treatment process, the ratio of aggregates with particle diameters of 800 μm or more in the area-based particle diameter distribution of the coated surface of the refractory substrate becomes 10% or less. In addition, the maximum height, which is an index of the surface roughness of the coated surface, is 200 μm or more and less than 400 μm. Here, the surface roughness is the sum of the height of the highest peak and the depth of the deepest valley in the contour curve in the reference length. In addition, the developed area ratio of the interface, which is an index of the surface roughness of the coated surface, is preferably 2.0 or more and less than 6.0. Here, the developed area ratio of the interface is an index that indicates the developed area of ​​the defined region, in other words, the degree to which the surface area of ​​the defined region has increased relative to the area of ​​the defined region.

[0028] The coating forming step is a step of spraying platinum or a platinum alloy onto the surface of the refractory substrate by a thermal spraying method such as plasma spraying. <Action of this embodiment> Next, examples and comparative examples of platinum-coated refractories will be described to illustrate the operation of this embodiment.

[0029] The platinum-coated refractories according to the examples are platinum-coated refractories manufactured by the above-mentioned manufacturing method. On the other hand, the platinum-coated refractories according to the comparative examples are platinum-coated refractories manufactured by the same manufacturing method as the examples, except that the aggregates are larger than those of the examples. That is, the platinum-coated refractories of the examples and the comparative examples are manufactured under the same conditions for the surface treatment step and the coating formation step.

[0030] Fig. 3 shows the state of the coated surface of the refractory substrate according to the embodiment, and Fig. 4 shows the state of the coated surface of the refractory substrate according to the comparative example. As shown in Figs. 3 and 4, the coated surface of the embodiment and the coated surface of the comparative example have different sizes of aggregate exposed on the surface. In detail, as shown in Fig. 3, the particle diameter of the aggregate is relatively small in the coated surface of the embodiment, whereas as shown in Fig. 4, the particle diameter of the aggregate is relatively large in the coated surface of the comparative example. In Figs. 3 and 4, the continuous portion where no aggregate is present is mainly composed of particles smaller than 100 μm.

[0031] FIG. 5 is a table showing the area-based particle size distribution per unit area of ​​the coated surface in the examples and comparative examples before the surface treatment process is performed. The particle size of the aggregate in the table shown in FIG. 5 can be obtained, for example, from the images shown in FIG. 3 and FIG. 4. Specifically, the cross-sectional area of ​​the particle is obtained from the images shown in FIG. 3 and FIG. 4, and converted into the diameter of a circle having the same area as the cross-sectional area, and the particle size is obtained. As shown in FIG. 5, the coated surface of the example is occupied only by aggregates having a particle size of less than 800 μm. In detail, the coated surface of the example is occupied by aggregates having a particle size of less than 100 μm in an area of ​​70% or more, aggregates having a particle size of less than 200 μm in an area of ​​80% or more, and aggregates having a particle size of less than 400 μm in an area of ​​90% or more. On the other hand, the coated surface of the comparative example has aggregates having a particle size of less than 100 μm and aggregates having a particle size of 2000 μm or more. In the coated surface of the comparative example, the area occupied by aggregates with particle diameters of less than 100 μm is 60% or more, and the area occupied by aggregates with particle diameters of less than 600 μm is 80% or more. Furthermore, in the coated surface of the example, the area occupied by aggregates with particle diameters of 800 μm or more is 0.0%, whereas in the coated surface of the comparative example, the area occupied by aggregates with particle diameters of 800 μm or more is 12.6%.

[0032] Next, the test results of the adhesion strength of the platinum coating 432 in the example and the comparative example will be described. The adhesion strength was calculated by carrying out the following test. An end face of a platinum ingot was joined to the platinum coating 432 of the manufactured platinum-coated refractory with Pt brazing. More specifically, a circular end face of a platinum ingot with a diameter of 5 mm was joined to the platinum coating 432. Next, the platinum ingot was pulled, so that a load was applied to the platinum coating 432 to separate the platinum coating 432 from the refractory substrate. The load at which the platinum coating 432 peels off from the refractory substrate was divided by the bonding area between the platinum coating 432 and the platinum ingot to calculate the adhesion strength.

[0033] In the case of the Example, the platinum coating 432 did not peel off from the surface of the refractory substrate, and a part of the refractory substrate broke. The tensile stress when the part of the refractory substrate broke was 12.7 MPa. In other words, it can be said that the adhesion strength between the surface of the refractory substrate and the platinum coating 432 was 12.7 MPa or more. In contrast, in the case of the Comparative Example, the platinum coating 432 peeled off from the surface of the refractory substrate when a tensile stress of 2.9 MPa was generated at the interface between the surface of the refractory substrate and the platinum coating 432. In other words, the adhesion strength between the surface of the refractory substrate and the platinum coating 432 was 2.9 MPa. Thus, the adhesion strength of the Example was 10 MPa or more, and the adhesion strength of the Comparative Example was less than 10 MPa.

[0034] <Effects of this embodiment> (1) The platinum-coated refractory uses fine ceramic particles as aggregate. For this reason, aggregate with a large particle size is unlikely to appear on the coated surface, and the coated surface tends to be rough. As a result, an anchor effect between the coated surface and the platinum coating 432 is easily obtained. Therefore, the platinum-coated refractory having the above configuration can increase the adhesive strength between the refractory substrate and the platinum coating 432.

[0035] (2) The maximum height, which is an index of the surface roughness of the coated surface, is 200 μm or more and less than 400 μm. In addition, the developed area ratio of the interface, which is an index of the surface roughness of the coated surface, is 2.0 or more and less than 6.0. Therefore, the platinum-coated refractory can further enhance the anchor effect between the coated surface and the platinum coating 432.

[0036] (3) When a coating surface containing a large amount of small-particle aggregate is subjected to blasting, the small-particle aggregate present on the coating surface is removed from the coating surface, and a more complex uneven shape is easily formed on the coating surface. Thus, the manufacturing method of the platinum-coated refractory can further enhance the anchor effect between the refractory substrate and the platinum coating.

[0037] (4) In the tube glass manufacturing apparatus 10, under the condition of manufacturing the tube glass, the air in the muffle furnace 40 contains boric acid components volatilized from the molten glass. When such air is cooled by the lower surfaces 43a, 43b of the upper wall 43 of the muffle furnace 40, the lower surfaces 43a, 43b are condensed. Here, in the muffle furnace 40 of the present embodiment, the first lower surface 43a of the upper wall 43 is inclined so as to descend toward the third side wall 423, and the second lower surface 43b of the upper wall 43 is inclined so as to descend toward the fourth side wall 424. Therefore, the liquid adhering to the lower surfaces 43a, 43b flows toward the third side wall 423 and the fourth side wall 424 along the first lower surface 43a and the second lower surface 43b. Therefore, the liquid adhering to the lower surfaces 43a, 43b is less likely to drip onto the molten glass supplied to the sleeve 31.

[0038] <Example of change> This embodiment can be modified as follows: This embodiment and the following modifications can be combined with each other to the extent that there is no technical contradiction.

[0039] The platinum-coated refractory material can be used in devices other than the glass tube manufacturing device 10. For example, it can be used as the wall of a glass melting furnace. The shape of the platinum-coated refractory can be appropriately changed depending on the application of the platinum-coated refractory. In the platinum-coated refractory, the platinum coating 432 is preferably provided at a required portion.

[0040] In the muffle furnace 40, the upper wall body 431 may have only one of the first lower surface 43a and the second lower surface 43b. Moreover, it is sufficient that at least the portion of the lower surfaces 43a and 43b of the upper wall 43 located above the sleeve 31 is inclined with respect to the horizontal direction.

[0041] In the muffle furnace 40, a platinum coating 432 may be provided on the surfaces of the side wall 42 and the partition wall 44 that face the sleeve 31. [Explanation of symbols]

[0042] 10...Glass tube manufacturing equipment 31...Sleeve 40…Muffle furnace 43...Top wall (an example of platinum-coated refractory material) 43a…First lower surface (an example of a coated surface) 43b…Second lower surface (an example of a coated surface) 431...Upper wall body (an example of a refractory base material) 432…Platinum coating

Claims

1. A platinum-coated refractory comprising a refractory substrate having ceramic particles as aggregate and a platinum coating which is a thermal spray coating on the refractory substrate, When the surface of the refractory substrate to be coated with the platinum coating is defined as a coated surface, In the coated surface, the proportion of aggregates having a particle size of 800 μm or more is 10% or less in the particle size distribution based on area per unit area. Platinum coated refractories.

2. The maximum height, which is an index of the surface roughness of the coated surface, is 200 μm or more and less than 400 μm. The platinum-coated refractory material according to claim 1.

3. The adhesion strength between the refractory substrate and the platinum coating is 10 MPa or more. The platinum-coated refractory material according to claim 1 or 2.

4. A tubular glass manufacturing apparatus comprising: a muffle furnace; and a sleeve disposed inside the muffle furnace, the molten glass being supplied to the sleeve and drawn out from a tip of the sleeve, the tubular glass manufacturing apparatus comprising: The platinum-coated refractory material according to any one of claims 1 to 3 is used as the refractory material constituting the upper wall of the muffle furnace. Tube glass manufacturing equipment.

5. A method for producing a platinum-coated refractory comprising a refractory substrate having ceramic particles as aggregate and a platinum coating coating the refractory substrate, A surface treatment step of roughening the surface of the refractory substrate, the surface having a particle size distribution based on an area per unit area in which aggregates having a particle size of 800 μm or more account for 10% or less; A coating forming step of forming the platinum coating on the coating surface by thermal spraying platinum or a platinum alloy, The surface treatment step is a step of blasting the coated surface. A method for manufacturing platinum-coated refractories.

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