JP6384666B2 - Heating element and manufacturing method thereof - Google Patents

Description

  The present invention relates to a heating element used as a heater in a manufacturing process of a glass article, for example, and an improved technique of the manufacturing method.

For example, as heating element for use as a heater in the manufacturing process of glass articles is known as a main component MoSi _2.

This heating element can be used stably in a high temperature region of 1000 ° C. or higher because Si of MoSi ₂ is selectively oxidized and a dense SiO ₂ Rich oxide protective film is formed on the surface.

However, in a low temperature range of 400 to 600 ° C., Mo and Si are oxidized simultaneously, and oxidation called “pesting” in which a porous layer composed of MoO ₃ and SiO ₂ is formed continuously proceeds. When this pasting progresses, the plastered part becomes fragile and may break at that part.

A heating element mainly composed of MoSi ₂ generally has a heating part and a terminal part. Since the temperature of the terminal portion is lower than that of the heat generating portion, there is a high possibility that the plastering proceeds. For this reason, in this type of heating element, there are many cases in which the lifetime of the terminal portion determines the life rather than the heating portion. Therefore, this type of heating element is particularly required to prevent the terminal portion from being plague.

  As a method for preventing such plastering, for example, Patent Document 1 proposes forming a metal layer selected from Cr, Ni, Rh, Ir, Pt and Au on a heating element. In other words, the formation of this metal layer prevents the metal layer from contacting the heating element and oxygen, thereby preventing plastering. And in patent document 1, thermal spraying, plating, ion plating etc. are mentioned as a formation method of this metal layer.

JP-A-8-81785

  However, thermal spraying, plating, ion plating, and the like require a predetermined facility and a predetermined operation, resulting in an increase in manufacturing cost.

  In view of the above circumstances, an object of the present invention is to prevent plastering while suppressing the manufacturing cost of a heating element.

The heating element according to the present invention, which was created to solve the above problems, has a heating part and a terminal part, is formed on the surface of the terminal part and includes a base material containing 70 wt% or more of MoSi ₂ and includes crystals. And an oxide layer.

  In this configuration, since the oxide layer containing crystals is formed on the surface of the terminal portion, the oxide layer containing crystals prevents oxygen from coming into contact with the surface of the terminal portion (base material). Therefore, it is possible to suppress the plastering of the terminal portion where plastering is likely to be a problem. And the oxide layer containing a crystal | crystallization can be formed by apply | coating the raw material to the surface of a terminal part. For example, brush coating or spraying can be used as the raw material coating method, and expensive equipment and complicated operations can be eliminated in order to form the oxide layer. Therefore, in the heating element according to the present invention, the manufacturing cost can be suppressed.

In the above configuration, the oxide layer, the _{SiO 2 40~60wt%, Al 2 O} 3 and 15 to 40 wt%, preferably contains 5-30 wt% of alkali metal oxides in total.

With this configuration, SiO _2, Al ₂ O _3, or the, there is heat resistance, can improve the heat resistance of the oxide layer. In addition, the alkali metal oxide constitutes a glass portion that bonds the SiO ₂ and Al ₂ O ₃ crystals in the oxide layer, thereby improving the sinterability of the oxide layer and increasing the strength of the oxide layer. Can be improved.

  Said structure WHEREIN: It is preferable that the glass layer is formed between the said base material and the said oxide layer.

  If it is this structure, since a glass layer has an effect which adhere | attaches an oxide layer and a base material, an oxide layer can be firmly attached to a base material.

  Said structure WHEREIN: It is preferable that the thickness of the said oxide layer is thicker than the thickness of the said glass layer.

  With this configuration, since the oxide layer that is less likely to transmit oxygen than the glass layer is thicker, the effect of preventing plastering can be obtained more reliably. Moreover, since the glass layer with a larger thermal expansion coefficient difference with a base material than an oxide layer is thin, it becomes difficult to break a glass layer, As a result, it can suppress that an oxide layer peels.

A method of manufacturing a heating element according to the present invention was invented in order to solve the above problems, has a heat generating portion and the terminal portion, the base material containing MoSi ₂ or 70 wt%, the surface of the terminal portion Further, it is characterized by applying a material for forming an oxide layer containing crystals by heating.

  In this configuration, the heating element having the opening configuration can be manufactured, and as a result, substantially the same effect as that of the heating element having the opening configuration can be obtained.

  Said structure WHEREIN: It is preferable that the said material contains 35-15 wt% of aluminosilicate salt, and 1-15 wt% of alkali metal hydroxide in total.

  Moreover, in the manufacturing method of a glass article, it is preferable to provide the process of heating molten glass using the heat generating body of said structure.

  As described above, according to the present invention, plastering can be prevented while suppressing the manufacturing cost of the heating element.

It is a schematic front view which shows the heat generating body which concerns on embodiment of this invention. It is a schematic sectional drawing of the surface vicinity in the terminal part of a heat generating body.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic front view showing a heating element 1 according to an embodiment of the present invention. In the present embodiment, the heating element 1 is used as a heater for heating the molten glass flowing through the feeder in the glass article manufacturing process. For example, the heating element 1 is used as a heater for melting the glass raw material. It may be a thing.

The heating element 1 includes a rod-like base material 2, and the base material 2 includes a heat generating part 3 and a terminal part 4 having a diameter larger than that of the heat generating part 3 provided at both ends of the heat generating part 3. In this embodiment, although the heat generating part 3 is U-shaped, it is not limited to this, A linear shape, a waveform shape, etc. may be sufficient. The base material 2 contains 70 wt% or more of MoSi ₂ . Examples of the remaining components of the substrate 2 include glass and ceramics.

  And the heat generating body 1 is provided in the surface of the terminal part 4, and is provided with the oxide layer 5 containing a crystal | crystallization. In the terminal portion 4, an aluminum layer 6 is formed on the end side opposite to the heat generating portion 3 in order to improve electrical contact, and a predetermined region on the heat generating portion 3 side from the aluminum layer 6 is formed. An oxide layer 5 is formed. In the illustrated example, the region where the oxide layer 5 is formed is a partial region of the terminal part 4 closer to the heat generating part 3 than the aluminum layer 6, but the entire part of the terminal part 4 closer to the heat generating part 3 than the aluminum layer 6. It may be a region.

The oxide layer 5 has a structure in which crystals such as SiO ₂ and Al ₂ O ₃ are bonded by a glass component. About the oxide layer 5, it is preferable that the difference of a thermal expansion coefficient with the base material 2 is less than ^5x10 < ^-6 > / ^degreeC . When the difference in thermal expansion coefficient between the oxide layer 5 and the substrate 2 exceeds 5 × 10 ⁻⁶ / ° C., the oxide layer 5 is cracked or peeled off due to the difference in thermal expansion from the substrate 2 during use. There is a possibility. From this viewpoint, the difference in coefficient of thermal expansion between the oxide layer 5 and the substrate 2 is more preferably within 3 × 10 ⁻⁶ / ° C., and most preferably within 1 × 10 ⁻⁶ / ° C. The thermal expansion coefficient of the base material 2 is 7 × 10 ⁻⁶ / ° C. to 8 × 10 ⁻⁶ / ° C.

  As shown in FIG. 2, a glass layer 7 is formed between the terminal portion 4 (base material 2) and the oxide layer 5. The oxide layer 5 is bonded to the substrate 2 by the glass layer 7. The thickness Ta of the oxide layer 5 is thicker than the thickness Tb of the glass layer 7.

  The thickness Ta of the oxide layer 5 is preferably 40 μm to 300 μm. When the thickness Ta is less than 40 μm, there is a possibility that the effect of preventing plastering cannot be obtained sufficiently. When the thickness Ta exceeds 300 μm, the thickness unevenness of the oxide layer 5 and the glass layer 7 may increase. From these viewpoints, the thickness Ta is more preferably 70 μm to 240 μm, and most preferably 80 μm to 180 μm.

  The thickness Tb of the glass layer 7 is preferably 0.5 μm to 20 μm. When thickness Tb is less than 0.5 micrometer, the effect which adhere | attaches the oxide layer 5 and the base material 2 is not fully acquired, and the oxide layer 5 may peel off. When thickness Tb exceeds 20 micrometers, the glass layer with a large thermal expansion coefficient difference with a base material tends to be broken, and oxide layer 5 may peel off. From these viewpoints, the thickness Tb is more preferably 1 μm to 15 μm, and most preferably 3 μm to 10 μm.

The oxide layer 5 preferably contains 40 to 60 wt% of SiO ₂ , 15 to 40 wt% of Al ₂ O _3, and 5 to 30 wt% of the total amount of alkali metal oxide. In the present embodiment, the content of the alkali metal oxide is the total amount of Na ₂ O and K ₂ O. However, the content of alkali metal oxide is the total amount of Na ₂ O and K ₂ O plus another alkali metal oxide, or the total amount of alkali metal oxides other than Na ₂ O and K ₂ O. Also good.

When the content of SiO ₂ is less than 40 wt%, the heat resistance of the oxide layer 5 may be reduced. When the content of SiO ₂ exceeds 60 wt%, the sinterability may be reduced. When the content of Al ₂ O ₃ is less than 15 wt%, the heat resistance of the oxide layer 5 may be reduced. When the content of Al ₂ O ₃ exceeds 40 wt%, the sinterability may be reduced. When the content (total amount) of the alkali metal oxide is less than 5 wt%, a portion for bonding the crystals is not sufficiently formed, the sinterability of the oxide layer 5 is lowered, and the strength of the oxide layer 5 is increased. May be reduced. When the content (total amount) of the alkali metal oxide exceeds 30 wt%, the heat resistance may be lowered.

From these viewpoints, the oxide layer 5, a _{SiO 2 42~58wt%, Al 2 O} 3 the 20～38Wt%, more preferably contains 7～25Wt% alkali metal oxides in total. Then, the oxide layer 5, a _{SiO 2 45~55wt%, Al 2 O} 3 the 25～35Wt%, and most preferably containing 10-20 wt% in total of alkali metal oxides.

The glass layer 7 preferably contains 65 to 75 wt% of SiO _{2, 1} to 10 wt% of Al ₂ O _3, and a total amount of alkali metal oxide of 20 to 35 wt%. In the present embodiment, the content of the alkali metal oxide is the total amount of Na ₂ O and K ₂ O. However, the content of alkali metal oxide is the total amount of Na ₂ O and K ₂ O plus another alkali metal oxide, or the total amount of alkali metal oxides other than Na ₂ O and K ₂ O. Also good.

When the content of SiO ₂ is less than 65 wt%, the heat resistance of the glass layer 7 may be lowered. When the content of SiO ₂ exceeds 75 wt%, the glass layer 7 may not be sufficiently formed. When the content of Al ₂ O ₃ is less than 1 wt%, the heat resistance of the glass layer 7 may be lowered. When the content of Al ₂ O ₃ exceeds 10 wt%, the glass layer 7 may not be sufficiently formed. When the content (total amount) of the alkali metal oxide is less than 20 wt%, the glass layer 7 is not sufficiently formed, and the oxide layer 5 may be peeled off. When content (total amount) of an alkali metal oxide exceeds 35 wt%, the heat resistance of the glass layer 7 may fall.

From these viewpoints, the glass layer 7 more preferably contains 67 to 73 wt% of SiO ₂ , ₃ to 8 wt% of Al ₂ O _3, and a total amount of alkali metal oxide of 22 to 33 wt%. The glass layer 7 most preferably contains 68 to 71 wt% of SiO _{2, 4} to 6 wt% of Al ₂ O _3, and a total amount of alkali metal oxide of 24 to 26 wt%.

  Next, a method for manufacturing the heating element 1 will be described. Since the base material 2 and the aluminum layer 6 can be manufactured by a well-known technique, description is abbreviate | omitted and the formation method of the oxide layer 5 and the glass layer 7 is demonstrated here.

  First, a material for forming an oxide layer containing crystals by heating (hereinafter referred to as an oxide layer raw material) is applied to the surface of the terminal portion 4 of the substrate 2. The application method is, for example, brushing or spraying.

  Next, a drying process is performed on the base material 2 coated with the oxide layer raw material. The drying treatment is performed at room temperature to 100 ° C. for 0.5 to 4 hours, for example.

  Thereafter, the base material 2 coated with the oxide layer raw material is subjected to heat treatment. The heat treatment is performed at 300 to 400 ° C. for 0.5 to 2 hours, for example. This completes the formation of the oxide layer 5 and the glass layer 7. In the present embodiment, the glass layer 7 is formed by integrating the component derived from the oxide layer raw material and the glass component derived from the substrate 2.

  The thickness of the oxide layer raw material layer immediately after coating is preferably 50 μm to 300 μm. When the thickness of the oxide layer raw material is less than 50 μm, the oxide layer 5 and the glass layer 7 to be formed may not be sufficiently formed. When the thickness of the oxide layer raw material layer exceeds 300 μm, the thicknesses of the formed oxide layer 5 and glass layer 7 may be uneven. From these viewpoints, the thickness of the oxide layer raw material is more preferably 80 μm to 250 μm, and most preferably 100 μm to 200 μm.

The oxide layer raw material preferably contains 35 to 50 wt% of an aluminosilicate salt and 1 to 15 wt% of the total amount of alkali metal hydroxide. Examples of the aluminosilicate salt include an alkali metal salt of aluminosilicate, and examples of the alkali metal include Na and K. In this case, the alkali metal salt of aluminosilicate may contain H ₂ O in the composition.

  In the present embodiment, the content of the alkali metal hydroxide is the total amount of NaOH and KOH. However, the content of the alkali metal hydroxide may be a total amount obtained by adding another alkali metal hydroxide to NaOH and KOH, or a total amount of alkali metal hydroxides other than NaOH and KOH.

  When the content of the aluminosilicate salt is less than 35 wt%, the heat resistance of the oxide layer 5 to be formed may be lowered. If the content of the aluminosilicate salt exceeds 50 wt%, the sinterability may be reduced. When the content (total amount) of the alkali metal hydroxide is less than 1 wt%, the glass portion for bonding the crystals of the oxide layer 5 is not sufficiently formed, and the sinterability of the formed oxide layer 5 is The strength of the oxide layer 5 to be formed may be lowered. Further, the glass layer 7 is not sufficiently formed, and the oxide layer 5 may be peeled off. When the content (total amount) of the alkali metal hydroxide exceeds 15 wt%, the heat resistance may be lowered.

  From these viewpoints, the oxide layer raw material more preferably contains 37 to 44 wt% of the aluminosilicate salt and 4 to 14 wt% of the total amount of the alkali metal hydroxide. The oxide layer raw material most preferably contains 40 to 43 wt% of the aluminosilicate salt and 6 to 13 wt% of the total amount of alkali metal hydroxide.

The oxide layer material, in addition to the components described above, the Al ₂ O ₃ preferably comprises 1~8wt%. When the content of Al ₂ O ₃ is less than 1 wt%, the heat resistance of the formed oxide layer 5 may be lowered. When the content of Al ₂ O ₃ exceeds 8 wt%, the sinterability may be reduced. From these viewpoints, the oxide layer raw material more preferably contains ₂ to 7 wt% of Al ₂ O ₃ in addition to the above components. The oxide layer raw material most preferably contains ₃ to 5 wt% of Al ₂ O ₃ in addition to the above components.

  Moreover, it is preferable that an oxide layer raw material contains 1-8 wt% of amorphous silica in addition to the above-mentioned component. When the content of the amorphous silica is less than 1 wt%, the glass portion for bonding the crystals of the oxide layer 5 is not sufficiently formed, and the sinterability of the formed oxide layer 5 is reduced and formed. There is a possibility that the strength of the oxide layer 5 is reduced. Further, the glass layer 7 is not sufficiently formed, and the oxide layer 5 may be peeled off. When the content of amorphous silica exceeds 8 wt%, the heat resistance may be reduced. From these viewpoints, the oxide layer raw material more preferably contains 2 to 7 wt% of amorphous silica in addition to the above-described components. The oxide layer raw material most preferably contains 3 to 5 wt% of amorphous silica in addition to the above components.

  Moreover, it is preferable that an oxide layer raw material contains 35-40 wt% of water in addition to the above-mentioned component. When the water content is less than 35 wt%, the dispersibility of the oxide raw material deteriorates. Further, depending on the coating method, water may be added to lower the viscosity.

  Moreover, it is preferable that an oxide layer raw material contains 1-8 wt% of adhesives, such as an acrylic resin, in addition to the above-mentioned component. When the content of the adhesive is less than 1 wt%, the raw material may peel off from the base material 2 during drying. When the content of the adhesive exceeds 8 wt%, the adhesive may remain in the oxide layer 5 during heating. From these viewpoints, the oxide layer raw material more preferably contains 2 to 7 wt% of the adhesive in addition to the above components. The oxide layer raw material most preferably contains 3 to 5 wt% of the adhesive in addition to the above components.

  Further, the oxide layer raw material may contain, for example, 1 to 5 wt% of cobalt oxide as an additive in addition to the above-described components. The oxide layer raw material may contain, for example, 1 to 5 wt% of a pigment such as an antimony compound or a trivalent chromium compound as an additive in addition to the above-described components.

  The heating element 1 configured as described above can enjoy the following effects.

  In the heating element 1, since the oxide layer 5 containing crystals is formed on the surface of the terminal portion 4, the oxide layer 5 prevents oxygen from coming into contact with the surface of the terminal portion 4 (base material 2). As a result, it is possible to suppress the plastering of the terminal portion 4 where the plastering tends to be a problem. The oxide layer 5 can be formed by applying an oxide layer raw material to the surface of the terminal portion 4. For example, brush coating or spraying can be used as the method for applying the oxide layer raw material, and it is possible to eliminate the need for expensive equipment and complicated operations in order to form the oxide layer 5. . Therefore, in the heating element 1 according to the present embodiment, it is possible to reduce the manufacturing cost.

  The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the technical idea. For example, in the said embodiment, although the heat generating body 1 was used as a heater in the manufacturing process of a glass article, you may be used in places other than the manufacturing process of a glass article.

DESCRIPTION OF SYMBOLS 1 Heat generating body 2 Base material 3 Heat generating part 4 Terminal part 5 Oxide layer 6 Aluminum layer 7 Glass layer Ta Thickness of oxide layer Tb Thickness of glass layer

Claims (5)

A base material having a heating part and a terminal part and containing 70 wt% or more of MoSi ₂ ;
An oxide layer formed on a surface of the terminal portion and including a crystal ;
A heating element, wherein a glass layer is formed between the substrate and the oxide layer . _2. The heating element according to claim 1, wherein the oxide layer contains 40 to 60 wt% of SiO ₂ , 15 to 40 wt% of Al ₂ O _3, and a total amount of alkali metal oxide of 5 to 30 wt%. . The heating element according to claim 1 or 2 , wherein a thickness of the oxide layer is larger than a thickness of the glass layer. For a base material having a heating part and a terminal part and containing 70 wt% or more of MoSi ₂ ,
Applying a material for forming an oxide layer containing crystals on the surface of the terminal portion by heating ,
The method for producing a heating element, wherein the material contains 35 to 50 wt% of an aluminosilicate salt and 1 to 15 wt% of a total amount of alkali metal hydroxide . The manufacturing method of the glass article characterized by including the process of heating a molten glass using the heat generating body of any one of Claims 1-3 .

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