JP2858583B2 - Joining method of zirconium oxide ceramic and metal - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for joining a zirconium oxide-based ceramic and a metal, for example, a steam electrolysis cell used in a steam electrolysis plant, a high temperature sensor, a solid oxide fuel cell. The present invention relates to the above-mentioned joining method applied when manufacturing a device or the like.

[Conventional technology]

Conventionally, ceramic and metal have been joined by mechanical methods such as fitting and shrink fitting, methods using organic / inorganic adhesives, and metallizing methods (metals with good wettability with the brazing material on the ceramic surface). A method of brazing after providing a thin layer), an active metal method (a method of adding an active metal to a brazing material in advance), a frit method (a method of using a glass containing a large amount of PbO as a brazing material), and solid-phase welding Various methods are known, such as the legal method (a method in which base materials are pressed against each other in a solid phase at a high temperature) ("Takayoshi Iseki,""CeramicResearch", Vol. 39, No. 39, pp. 29-34, "Mechanical Research"). Joining technology ").

[Problems to be solved by the invention]

When a zirconium oxide ceramic is attached to a metal part and used as a steam electrolysis cell, high-temperature sensor, solid oxide fuel cell, etc., the joint with the metal part is a reliable product with airtightness and heat resistance. For this purpose, a large bonding strength is required.

However, as shown in Table 1, each of the conventional joining methods has advantages and disadvantages, and none of them satisfy airtightness, heat resistance, and joining strength.

In Table 1, the mating materials for mechanical joining, adhesive joining, and brazing are low alloy copper, stainless steel, Ni or Ni-based alloys, etc. The mating materials for solid-phase joining are Au, Pt, soft Al, Cu, Ni in the metal method, and Al / Kovar / W in the cemented carbide method.

Also, in the case of brazing in Table 1, special care is required because zirconium oxide-based ceramics have poor wettability.

In view of the above, an object of the present invention is to propose a joining method of a zirconium oxide-based ceramic and a metal that satisfies all of hermeticity, heat resistance, and joining strength.

[Means for solving the problem]

In order to solve the above-mentioned object, the present invention provides: (1) When bonding a zirconium oxide-based ceramic to a metal, the ceramic surface on the side to be bonded to the metal is coated with an Al ₂ O ₃ or Cr ₂ O ₃ thin film; Thickness from thin film side 1
5 μm Ti, 50-150 μm thick silver braze, 0.2-2.0 m thick
m of nickel, a silver braze having a thickness of 20 to 30 μm, and a metal to be joined are laminated thereon, and heated to a temperature equal to or higher than the melting point of the silver braze in a vacuum furnace or an inert gas atmosphere. A method of joining a zirconium oxide-based ceramic and a metal.

(2) Instead of coating the Al ₂ O ₃ or Cr ₂ O ₃ thin film in the above method, coat the ceramic joint surface with Al or Cr,
A method for bonding a zirconium oxide-based ceramic and a metal, which oxidizes the coating to form an Al ₂ O ₃ or Cr ₂ O ₃ thin film.

(3) When joining the zirconium oxide-based ceramic and the metal, the composition of the zirconium oxide-based ceramic near the joint is made of a mixture with Al ₂ O _3, and the joint surface is made 100% of Al ₂ O ₃ and the joint surface is made. Ti with thickness of 1-5μm from side, thickness
A 50-150 μm silver braze, a 0.2-2.0 mm thick nickel, and a 20-30 μm thick silver braze are laminated, and the metal to be joined is laminated thereon, in a vacuum furnace or in an inert gas atmosphere. And heating the zirconium oxide-based ceramic to a metal by heating to a temperature equal to or higher than the melting point of the silver braze.

[Action]

In the electrolysis of water vapor by a zirconium oxide-based ceramic solid electrolyte, a voltage is applied to electrodes (for example, platinum paste coating) attached to both sides of the electrolyte to cause a current to flow, so that water (H ₂ O) on one electrode side is converted to hydrogen ( H)
And oxygen (O), and the heat resistance of the joint is 700 ° C. or more by brazing the joint portion with silver according to the present invention.

In addition, the bonding strength of zirconium oxide ceramic
Compared to those directly joined (about 7 kg / mm ² ) without coating the ₂ O ₃ and Cr ₂ O ₃ thin films, or setting the composition of the zirconium oxide-based ceramic joint to the gradient composition with Al ₂ O ₃ As a result, the weight reached 15 kg / mm ^{2, which} was more than doubled, and was broken at a zirconium oxide-based ceramic portion remote from the joint.

In addition, Al ₂ O ₃ , Cr ₂
As shown in FIG. 4, the direct bonding without coating the O ₃ thin film or the composition of the bonding portion of the zirconium oxide ceramic with the gradient composition with Al ₂ O ₃ has a high bonding strength in a high temperature atmosphere as shown in FIG. Compared with the remarkable decrease, it was confirmed that the one joined by the method of the present invention hardly reduced the strength.

Fig. 5 summarizes the effect of Ti, brazing material (between ceramic and Ni insert) and the thickness of Ni insert on the joining strength (breaking strength), where Ti is 1-5 µm and brazing material is 50- It is understood that the preferred range for the strength of a 150 μm Ni insert is 0.5 to 2.0 mm, and those outside these ranges significantly reduce the strength.

Note that the bonding strength referred to in FIGS. 4 and 5 indicates a breaking strength obtained by a four-point bending test (JIS method).

In addition, the method of forming the Al ₂ O ₃ , Cr ₂ O ₃ (or Al, Cr) thin film should be performed by sputtering or ion plating, since the coating film must be non-porous and must not mix impurities. Coating methods such as CVD are unsuitable. In general, the thickness of these thin films is
The range is preferably 0.1 to 5 μm, and particularly preferably about 1 μm.

Examples of the metal to be bonded to the zirconium oxide-based ceramic include Kovar and an Fe-Cr alloy having a similar thermal expansion coefficient to Kovar (for example, SHOMAC RIVER 26), and Cr and W having a smaller thermal expansion coefficient than the zirconium oxide-based ceramic. Can be used.

An embodiment according to the present invention will be described in detail with reference to FIGS.

Example 1 As shown in FIG. 1, yttria-stabilized zirconia coated with Al ₂ O ₃ by sputtering (hereinafter referred to as YSZ).
And joining of a Kovar alloy (Fe-Ni-Co alloy) will be described.

A with a thickness of 0.5 μm by sputtering on the bonding surface of YSZ1
After l ₂ O ₃ 3a is deposited, 3 μm thick Ti 4a, 100 μm thick silver brazing (BAg-8) 5a, 1.0 mm thick Ni 6a, 30 μm thick silver brazing from the bonding surface side of YSZ1 (BAg-8) 5b and Kovar alloy 2 were installed and heated to 850-860 ° C in a vacuum furnace.
After cooling to near room temperature, take out from the furnace.

Cr ₂ O ₃ may be sputtered instead of Al ₂ O _{3 in} the first embodiment.

Example 2 With reference to FIG. ₂ , a description will be given of the bonding of YSZ and Kovar alloy in which Al is ion-plated and then oxidized to form an Al ₂ O ₃ thin film on the bonding surface.

1μ of Al 3b for ion plating on the bonding surface of YSZ1
After coating with a thickness of m, a heat treatment was performed in the air at 900 ° C. for 1 hour. Next, Ti with a thickness of 1.5 μm from the joint surface of YSZ1
4b, 100 µm thick silver brazing (BAg-8) 5a, 0.5 mm thick N
i6b, silver brazing (BAg-8) 5b having a thickness of 30 μm, and Kovar alloy 2 are installed, heated to 850 to 860 ° C. in a vacuum furnace, cooled to near room temperature, and then taken out of the furnace.

As described above, Cr may be ion-plated instead of Al in the second embodiment.

Example 3 a by Figure 3, the composition of the YSZ near the junction and a mixture of Al ₂ O _3, gradually Al ₂ O ₃ in accordance toward the joint direction
The case where the ratio of Al ₂ O ₃ is increased to 100% at the joint surface and the joint of the Kovar alloy are described.

First, YSZ and Al ₂ O ₃ are used as raw materials, and those having a single composition and a mixture ratio of YSZ / Al ₂ O ₃ of 7/3, 5/5, 3/7 are prepared.
YSZ / Al ₂ O ₃ ratio 10/0, 7 / to 10φ × 50lmm rubber press type
3, 5/5, 3/7, and 0/10 were injected in 10 mm increments, and calcined at about 1800 ° C. after calcination to produce a gradient composition YSZ / Al ₂ O ₃ .

Next, with the Al ₂ O ₃ side of the gradient composition YSZ / Al ₂ O ₃ 1 as the bonding surface, Ti3 having a thickness of 5 μm from the bonding surface side, silver brazing (BAg-8) 4a having a thickness of 100 μm, and a 1.0 mm thickness Ni 5, silver solder (BAg-8) 4b having a thickness of 30 μm and Kovar alloy 2 to be joined are installed.
After heating to 850 to 860 ° C in a vacuum furnace, it is cooled and then taken out of the furnace.

In the above embodiment, only the special embodiment of the present invention has been described, but the joining metal is a Kovar alloy (Fe-Ni-
(Cr alloy), it is also possible to use Fe-25Cr alloy (SHOMAC RIVER 26), chromium, W, etc. Also, brazing can be performed using an inert gas atmosphere furnace such as argon gas instead of a vacuum furnace. Good.

〔The invention's effect〕

According to the present invention, when a zirconium oxide-based ceramic is joined to a metal, the bending strength of the joint is, for example, 15 kg / mm, which is more than double that of direct joining of YSZ and a Kovar alloy (about 7 kg / mm ² ).
mm ² , and fractured at the YSZ portion away from the joint. (YS
Z flexural strength is about 10-15 kg / mm ^2. Further, as shown in FIG. 4, even when used in a high-temperature atmosphere, a decrease in bonding strength was hardly observed, and excellent heat resistance and durability were exhibited.

As a result of further the airtightness of the joint portion was measured by He leakage test, the leakage rate or without heating, ^10-9
It had sufficient airtightness at ACC / sec or less.

[Brief description of the drawings]

1 to 3 are explanatory views of first to third embodiments of the present invention,
FIG. 4 shows a comparison between the bonding strength of a zirconium oxide-based ceramic (YSZ) and a metal (Kovar) in a high-temperature atmosphere obtained by the method of the present invention, and the same bonding strength by direct brazing of YSZ and Kovar by a conventional method. FIG. 5 is a chart showing the effect of the thickness of the Ti, brazing material and Ni insert material used in the present invention on the bonding strength.

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Shoji Nakamori 2-1-1 Shinama, Arai-machi, Takasago City, Hyogo Prefecture Inside the Takasago Research Laboratory, Mitsubishi Heavy Industries, Ltd. (72) Inventor Shoji Hirai 2-1-1 Shinama, Arai-machi, Takasago City, Hyogo Prefecture No. 1 In the Takasago Research Laboratory, Mitsubishi Heavy Industries, Ltd. (72) Atsushi Nagato, 1-1 1-1 Wadazakicho, Hyogo-ku, Kobe, Hyogo Prefecture Inside the Kobe Shipyard, Mitsubishi Heavy Industries, Ltd. 1-1-1, Wadazakicho, Hyogo-ku, Mitsubishi Heavy Industries, Ltd.Kobe Shipyard (72) Inventor Kazuaki Nemoto 1-1-1, Wadasakicho, Hyogo-ku, Kobe, Hyogo, Japan Inventor Hiroyuki Sato 1-1-1, Wadazaki-cho, Hyogo-ku, Kobe-shi, Hyogo Prefecture Inside Mitsubishi Heavy Industries, Ltd.Kobe Shipyard (56) Reference Document JP-A-2-188476 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C04B 37/02

Claims (3)

(57) [Claims] When bonding a zirconium oxide-based ceramic to a metal, the ceramic surface on the side to be bonded to the metal has Al
₂ O ₃ or Cr ₂ O ₃ thin film is coated, and from the thin film side, Ti having a thickness of 1 to 5 μm, silver brazing having a thickness of 50 to 150 μm, and a thickness of 0.2 to
2.0mm nickel, 20 ~ 30μm thick silver braze laminated,
A method for bonding a zirconium oxide-based ceramic and a metal, comprising laminating a metal to be bonded thereon and heating the metal in a vacuum furnace or an inert gas atmosphere to a temperature equal to or higher than the melting point of the silver solder. 2. The ceramic bonding surface is coated with Al or Cr instead of the coating of the Al ₂ O ₃ or Cr ₂ O ₃ thin film according to claim 1, and the coating is oxidized to Al ₂ O ₃ or Cr ₂ A method for bonding a zirconium oxide-based ceramic and a metal, comprising forming an O ₃ thin film. Upon wherein joining zirconium oxide-based ceramics and metal, the composition of the zirconium oxide-based ceramics in the vicinity of the joint as a mixture of Al ₂ O _3, of gradual Al ₂ O ₃ in accordance toward the joint direction Increase the ratio, A
l ₂ O ₃ 100% and a thickness of 1 to 5
μm Ti, 50-150 μm thick silver braze, 0.2-2.0 mm thick
Of nickel, a silver braze having a thickness of 20 to 30 μm, and a metal to be joined thereon are laminated, and heated in a vacuum furnace or an inert gas atmosphere to a temperature equal to or higher than the melting point of the silver braze. Characteristic method of joining zirconium oxide ceramic and metal.