JP2002214052A - Thermocouple for molten metal and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermocouple for a molten metal which is excellent in durability with no variation among products. SOLUTION: There are provided a sintered rod 10A of insulating ceramics where a pair of print wirings 8 and 9 comprising heterogeneous metal constituting a thermocouple are arranged in axial direction, a measuring contact point 12 where the chips of the pair of print wirings 8 and 9 are connected with a tip 13 of the sintered rod 10A, a laminated part 7 where an insulating ceramics layer 6a and an Mo-ZrB2 layer 6b are alternately combined on the outside surface of the sintered rod 10A, and a reference contact point which connects a potentiometer to the base end of the pair of print wirings 8 and 9. The laminated part 7 is sintered together with the sintered rod 10A integrally.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermocouple for molten metal having excellent durability suitable for measuring the temperature of molten metal such as cast iron molten metal and a method for producing the same.

[0002]

2. Description of the Related Art As an alternative to a consumable thermocouple conventionally used for measuring the temperature of a molten metal, the present applicant has disclosed a tungsten-rhenium inside a protective tube made of silicon nitride Si ₃ N _4. (W-5Re, W-26Re) accommodates a pair of metal strands and heat-resistant glass powder or reaction-sintered silicon nitride containing silicon nitride Si ₃ N ₄ as a main component in the space of the protection tube
A thermocouple for molten metal filled with Si ₃ N ₄ powder is proposed. This is because the product tends to vary depending on the filling amount of powder such as heat-resistant glass.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a thermocouple for molten metal which has excellent durability and has no variation in products, and a method of manufacturing the same.

[0004]

According to the present invention, there is provided a thermocouple comprising a dissimilar metal constituting a thermocouple.
A rod-shaped sintered body made of an insulating ceramic in which a pair of printed wirings in the axial direction are disposed; a measuring contact formed by connecting the tips of the pair of printed wirings at the tip of the rod-shaped sintered body; A reference contact is provided for connecting the base ends of the pair of printed wirings and the potentiometer.

Further, according to the manufacturing method of the present invention, a pair of conductive pastes containing a dissimilar metal constituting a thermocouple is printed on the surface of a rod-shaped molded body made of insulating ceramic, and the tip of the printed wiring in the axial direction is printed. Are connected at the tip of the rod-shaped molded body to form a measurement contact, and a binder is formed by laminating a multilayer sheet in which an insulating ceramic layer is superimposed on _two layers of molybdenum-zirconium boride Mo-ZrB on the rod-shaped molded body. And a step of degreasing the rod-shaped molded body around which the multilayer sheet is wound and removing the binder, and pressing the rod-shaped molded body around which the multilayer sheet is wound by a hot press method or an atmosphere firing method. The method is characterized by comprising a step of heating and sintering, and a step of connecting a pair of compensating conductors to the base ends of the pair of printed wirings.

[0006]

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermocouple W-5Re.
Outer surface of rod-shaped molded body (green body) made of insulating ceramics such as silicon nitride Si ₃ N _{4 in} which a pair of printed wirings containing dissimilar metals such as W-26Re, Pt and Pt-Rh are arranged in the axial direction Insulating ceramic layer such as silicon nitride Si ₃ N ₄ and Mo-ZrB
_A laminated portion composed of a molybdenum-based compound layer such as No. ₂ is joined, and the rod-shaped molded body and the laminated portion are sintered integrally to form a rod-shaped sintered body. The tips of the pair of printed wirings are connected at the tips of the bar-shaped molded body to form measurement contacts. The base ends of the pair of printed wirings are used as reference contacts for connecting a potentiometer.

Specifically, a multilayer sheet in which a molybdenum-based compound layer and an insulating ceramic layer are superposed is wound on the outer surface of a rod-shaped formed body made of insulating ceramic on which a pair of printed wirings are provided, while being laminated. Then, it is pressed and densified by a hot pressing method or an atmosphere firing method to be sintered while being densified to obtain a rod-shaped sintered body.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIGS. 1 to 3, a thermocouple for molten metal according to the present invention has an insulating property in which a pair of axial printed wirings 8 and 9 including dissimilar metals constituting a thermocouple are arranged on the outer surface. A rod-shaped sintered body 10A made of ceramic and a pair of printed wirings 8 and 9
A measuring contact 12 formed by connecting the tip of the rod-shaped sintered body 10A with a tip 13 of the rod-shaped sintered body 10A, and a laminate in which an insulating ceramic layer 6a and a Mo-ZrB ₂ layer 6b are alternately connected to the outer surface of the rod-shaped sintered body 10A. And a reference contact connecting the base ends of the pair of printed wirings 8 and 9 and a potentiometer.
Sintered with OA.

In order to manufacture a thermocouple for molten metal according to the present invention, silicon nitride Si ₃ N ₄ , yttria Y ₂ O ₃ and alumina
A rod-shaped compact (green body) 10 molded from a mixed powder of Al ₂ O ₃ and molybdenum-zirconium boride Mo-ZrB ₂
A ceramic layer 6a made of a mixed powder of silicon nitride Si ₃ N ₄ , yttria Y ₂ O _3, and alumina Al ₂ O ₃ is overlaid on a molybdenum-based compound layer 6 b of a thickness of 50 to 100 μm.
The multilayer sheet 6 is prepared, and as shown in FIG. 4, axial printed wirings 8 and 9 constituting a thermocouple are printed on the outer surface of the rod-shaped molded body 10 at intervals in the circumferential direction, Printed wiring 8, 9
Are superimposed on the tip 13 of the rod-shaped molded body 10 to form the measurement contact 12. For the printed wirings 8 and 9, a conductive paste obtained by mixing a binder with a different metal powder such as W-5Re and W-26Re and Pt and Pt-Rh which constitute a thermocouple is used.

As shown in FIGS. 4 and 5, a rod-shaped molded body 10 provided with printed wirings 8 and 9 is placed on a multilayer sheet 6 in which a ceramic layer 6a is laminated on a molybdenum-based compound layer 6b and rolled. While moving, the multilayer sheet 6 is wound around the outer surface of the rod-shaped molded body 10. As shown in FIG.
0A is a laminate 7 having a desired thickness with the rod-shaped molded body 10 as a core.
Is formed, and a protective layer 6c of a molybdenum-based compound is formed on the outer surface of the laminated portion 7.

Connection terminals 4 and 5 made of metal or conductive ceramics connected to the printed wirings 8 and 9 are previously connected to the base end of the rod-shaped molded body 10. Further, one edge of the multilayer sheet 6 is wound sideways longer by a length s than the tip end of the rod-shaped molded body 10 provided with the measurement contacts 12, and the extended portion indicated by the length s is rod-shaped. It is narrowed down to the axis of the body 10 so as to cover the measurement contact 12.

A molybdenum-based compound layer 6b and a ceramic layer 6a such as silicon nitride Si ₃ N ₄ are superimposed on a rod-shaped molded body 10 made of insulating ceramic such as silicon nitride Si ₃ N ₄ formed as described above. The multilayer sheet 6 wound in multiple layers is loaded into a mold and pressurized at a temperature of about 130 ° C.
By sintering at 0 to 1400 ° C. by a hot press method or an atmosphere firing method, a rod-shaped sintered body 10A is obtained.

Finally, compensation leads 2, 3 are connected to connection terminals 4, 5, respectively.
Are connected to each other, and the ends of the connecting wires 2 and 3 are used as reference contacts for connecting a potentiometer (not shown). Compensating conductors 2, 3
Is used to connect the measuring contact 12 and a reference contact (maintaining a predetermined temperature) for connecting the potentiometer. The printed wirings 8 and 9 and the compensating conductors 2 as metal wires constituting the thermocouple are connected.
The thermoelectric characteristics of No. 3 are matched.

In the thermocouple for molten metal configured as described above, printed wirings 8 and 9 connected to a rod-shaped sintered body 10A made of ceramics having heat resistance and insulating properties are measured by connecting their tips to each other. The contact sheet 12 is formed, the base ends of the printed wirings 8 and 9 are connected to the connection terminals 4 and 5, and the multilayer sheet 6 is formed by laminating the ceramic layer 6a on the molybdenum-based compound layer 6b. When the temperature is measured by immersing the thermocouple for molten metal in the molten metal, when compared with the conventional thermocouple for molten metal indicated by line 16 in FIG. The thermocouple for use has excellent responsiveness as shown by the line 15 and has high durability against thermal shock and mechanical shock received by the thermocouple for molten metal,
Even if a crack is generated on the outer surface of the thermocouple for molten metal, the internal progress of the crack is suppressed in the laminated portion 7 of the multilayer sheet 6.

The protective layer 6c made of the molybdenum-based compound layer 6b enhances the corrosion resistance to the molten metal, suppresses the adhesion of the molten metal, and renders the conventional consumable-type molten metal thermocouple unusable three times. On the other hand, the thermocouple for molten metal according to the present invention can withstand 750 repetitions.

[0016]

As described above, the present invention provides a rod-shaped sintered body made of an insulating ceramic in which a pair of axial printed wirings including dissimilar metals constituting a thermocouple are disposed. A measuring contact formed by connecting a leading end of the printed wiring at a leading end of the rod-shaped sintered body; and a reference contact connecting a base end of the pair of printed wirings and a potentiometer. Is stable without being eroded around the measurement contact, and reproducibility can be obtained even when used repeatedly.

Since a thermocouple printed wiring is applied to a rod-shaped molded product made of an insulating ceramic, a multilayer sheet containing a molybdenum-based compound Mo-ZrB ₂ is wound, and then sintered while being pressed and heated. Excellent durability with no variation in product dimensions.

[0018] Since the outer surface of the rod-shaped sintered body is covered with a protective layer of a molybdenum-based compound Mo-ZrB ₂ the multilayer sheet is excellent in corrosion resistance against molten metal.

[Brief description of the drawings]

FIG. 1 is a front sectional view of a thermocouple for molten metal according to the present invention.

FIG. 2 is a plan sectional view of a base end of the thermocouple for molten metal.

FIG. 3 is a plan sectional view of a distal end portion of the thermocouple for molten metal.

FIG. 4 is a perspective view showing a manufacturing process of the thermocouple for molten metal.

FIG. 5 is a perspective view showing a manufacturing process of the thermocouple for molten metal.

FIG. 6 is a diagram showing the results of a test on the responsiveness of the thermocouple for molten metal.

[Explanation of symbols]

2: Compensating conductor 3: Compensating conductor 4: Connection terminal 5: Connection terminal 6: Multilayer sheet 6a: Ceramic layer 6b: Molybdenum-based compound layer 6
c: protective layer 7: laminated part 8: printed wiring 9: printed wiring 10: rod-shaped molded body 10
A: Rod-shaped sintered body 12: Measurement contact 13: Tip

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 35/02 H01L 35/22 35/20 35/34 35/22 C21C 5/46 A 35/34 7 / 00 R // C21C 5/46 C04B 35/58 102Y 7/00 302Y

Claims (12)

[Claims] 1. A rod-shaped sintered body made of an insulating ceramic in which a pair of axial printed wirings including a dissimilar metal constituting a thermocouple is disposed, and the tip of the pair of printed wirings is formed by the rod-shaped firing. A thermocouple for molten metal, comprising: a measurement contact connected at a distal end portion of a unit; and a reference contact connecting a base end of the pair of printed wirings and a potentiometer. 2. The thermocouple for molten metal according to claim 1, further comprising a laminated portion in which an insulating ceramic layer and a molybdenum-based compound layer are alternately bonded on an outer surface of said rod-shaped sintered body. 3. The thermocouple for molten metal according to claim 1, wherein a protective layer of a molybdenum-based compound is formed on an outer surface of said laminated portion. 4. The thermocouple for molten metal according to claim 1, wherein said rod-shaped sintered body is made of one of silicon nitride and sialon. 5. The thermocouple for molten metal according to claim 1, wherein said pair of printed wirings is made of an alloy having different components from tungsten-rhenium W-Re. 6. A printed wiring according to claim 1, wherein said pair of printed wirings is platinum-rhodium Pt-R.
The thermocouple for molten metal according to claim 1, wherein h is made of an alloy whose components are different from each other. Wherein said protective layer is a molybdenum - boride zirconium Mo-ZrB _2, a thermocouple for molten metal according to claims 1 to 6. 8. A pair of conductive pastes containing a dissimilar metal constituting a thermocouple is printed on the surface of a rod-shaped molded body made of an insulating ceramic, and the tip of the printed wiring in the axial direction is formed on the rod-shaped molded body. Forming a measurement contact by connecting at the tip, and molybdenum-zirconium boride Mo
A step of winding and laminating a multilayer sheet obtained by laminating an insulating ceramic layer on _two layers of -ZrB via a binder, and a step of degreasing and removing the binder from the rod-shaped molded body wound with the multilayer sheet; It comprises a step of sintering the rod-shaped formed body around which the multilayer sheet is wound by applying pressure and heating by a hot press method or an atmosphere firing method, and a step of connecting a pair of compensating conductors to the base ends of the pair of printed wirings. A method for producing a thermocouple for molten metal, comprising: 9. The method according to claim 8, wherein the insulating ceramic is one of silicon nitride and sialon. 10. The method of manufacturing a molten metal thermocouple according to claim 8, wherein said pair of printed wirings are made of a tungsten-rhenium W-Re alloy having different components. 11. The method for manufacturing a thermocouple for molten metal according to claim 8, wherein said pair of printed wirings is a platinum-rhodium Pt-Rh alloy having different components. 12. An outer surface of a laminated portion formed by the multilayer sheet,
Molybdenum-zirconium boride Mo-ZrB _Two Form protective layer
The method for producing a thermocouple for molten metal according to claim 8.