JPS6228067A - Joining method for ceramics - Google Patents

Abstract

PURPOSE:To surely join ceramics and member to be joined even in an oxidative atmosphere by using a brazing filler metal contg. >=80wt% mixed compsn. having silver, tin and copper for joining the ceramics and the member to be joined. CONSTITUTION:The brazing filler metal forms a metallized layer (metallic coating layer) and the brazing filler metal itself acts as a joining material in joining of the ceramics to each other. The compounding ratios of the three components; silver, tin and copper are preferably selected within the range of 1-25wt% tin and 1-20wt% copper with respect to 95-70wt% silver which is the essential component. The satisfactory joining of the ceramics, more particularly oxide ceramics is attained and the good metallized layer is obtd. on the joint surface of the ceramics when copper is added to the brazing filler metal in the above-mentioned manner. The ceramics coated by the metallized layer are heated and calcined in an oxidative atmosphere or inert atmosphere.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for joining ceramics, and particularly to a method for joining ceramics together and ceramics and metals in an oxidizing atmosphere.

[Conventional technology]

Conventionally, the Telefunken method, active metal method, and hydride compound method have been used as bonding methods for oxide ceramics.

Copper oxide method (US Pat. No. 3,180,758) and the like are known.

[Problems with conventional technology]

However, these methods involve complicated processes and often do not have sufficient bonding strength or thermal shock resistance.For example, in the Telefunken method, 13
It requires complex work processes such as high-temperature baking at 00 to 1,700 degrees Celsius, metal plating, stabilization treatment, and brazing process, and has the disadvantage that it is also affected by the components in the parts to be joined (Haruo Takashio: Ceramics Association Journal, 79 (
9) 1!1171) Also, the active metal method requires a vacuum or an inert atmosphere, and T
It has the disadvantage that i and Zr tend to lose their activity depending on the amount of oxygen in the furnace. Furthermore, when zirconia ceramics are bonded at high temperatures in such an inert atmosphere or vacuum, oxygen defects are likely to be introduced, which significantly impairs the appearance. In addition, if the bonding layer is thin, the bonding layer cannot alleviate the residual stress caused by the difference between the ceramic and the metal, and the ceramic may crack or peel, causing the ceramic and the parts to be bonded to be separated. Another drawback was that it was not possible to join reliably.

Therefore, the present invention provides a joining method that allows joining even in an oxidizing atmosphere.

[Technical means and effects of the present invention]

In the present invention, ceramics and members to be joined are joined using a brazing material containing 80% by weight or more of a mixed composition containing silver, tin, and copper.

The brazing material in the present invention forms a metallizing layer (metal coating layer), and acts as a bonding material itself when bonding ceramics together. the above,
The blending ratio of the three components of silver, tin, and copper is 95% to 95% silver, which is the main component.
With respect to 70% by weight, a range of 1 to 25% by weight of tin and 1 to 20% by weight of copper is suitable. Three or all parts of tin and copper may be replaced by metal oxides, and part of silver may be replaced with metal oxides.

Titanium (T
i) Metals with high reactivity with oxide ceramics, such as chromium (Or), zirconium (Zr), and nickel (Ni), or their oxides, alone or in combination, for a total of 20
It can be contained within a range of % by weight or less. Further, when the three components mentioned above are metals, each may be a metal powder, a foil or powder of an alloy consisting of the three components, or a combination of individual metal foils. Further, of the three components, some powder and some foil may be used.

The present invention is based on the knowledge that good bonding with ceramics, especially oxide ceramics, can be obtained by adding copper to the brazing material (UK Patent No. 781).
045), a good metallized layer cannot be obtained with only silver and copper and segregation is observed, and a good metallized layer cannot be obtained with only copper and tin.

However, it has been found that by using three components of silver, tin, and copper, wettability is improved and a good metallized layer can be obtained on the bonding surface of ceramics. By adding tin, as described above, it is possible to achieve good wettability, lower the melting point of the brazing material, and suppress brewing. Furthermore, as shown in FIG. 1, in joining the metal 1 and the ceramic 2, tin is diffused and segregated from the BAG silver solder 3 onto the surface of the metal 1 to enhance the adhesion effect. The strength of the metallized layer 4 on the ceramic 2 is most strongly related to copper oxide, and tin oxide and silver oxide are also slightly related.

The metallized layer 4 has a thickness of about 20 to 40 pm,
Tin oxide and copper oxide are in a mixed state with metallic silver, and as shown in FIG. Ru. With this form, the tin oxide and the copper oxide 5 produce a strong bonding force, and the malleability of the silver 6 itself makes it possible to alleviate the residual stress caused by the difference in thermal expansion between the ceramic and the metal. Therefore, there is no need for a separate intermediate layer for stress relaxation.

In the method for joining ceramics according to the present invention, when applying a coating layer (metallized layer), silver, copper, or tin may be used as a powder and sprinkled, but usually a suitable binder and its solvent are used. For example, use an appropriate amount of printing ink such as screen oil, balsam, etc., and apply it in the form of a paste. When coating or distributing a powder or paste coating layer on a ceramic surface, the coating amount is determined as appropriate depending on the purpose.

Next, the ceramic coated with the metallized layer is heated and baked in an oxidizing atmosphere or an inert atmosphere.In the present invention, the oxidizing atmosphere is used under special conditions such as controlling the oxygen partial pressure. Although an inert atmosphere and a pressurized atmosphere are also permissible, an oxidizing atmosphere is preferable in order to join metal oxide ceramics containing Zr, Ti, etc. in a manner that does not impair their appearance quality during heating.

The heating conditions in this case vary somewhat depending on the shape, size, and coating amount of the ceramic, but heat at a temperature increase rate of 10°C/win or higher for about 1 to 30 minutes at a temperature of 950 to 1300°C, and then heat to 15°C/win for about 1 to 30 minutes. Cooling at a speed higher than win. Preferably, at a heating rate of 30°C/min or more,
It is heated at 150°C for 10 minutes and cooled at about 30°C/sin. The baked coating layer can be joined by soldering, brazing material, etc. without providing a plating layer.

According to the method for bonding ceramics according to the present invention, it is effective for bonding oxide ceramics and can have a bonding layer as thin as 40 pm. Moreover, especially in zirconia, it is possible to bond with a good bonding state and good appearance without producing oxygen defects.

Ceramics that can be used in the bonding method of the present invention include alumina, zirconia, magnesia, spinels, forsterites, and other metal oxide ceramics.

The metal to be joined is copper iron or special steel such as SS, SC, SK, SUS, Ni-0r, Fe-Xl, Fe.
-Xl-Go and other alloys can be broadly targeted. Also,
By providing a reprinted cemented carbide brazing material layer in contact with the brazing material layer of the present invention, bonding with cemented carbide tool materials such as WC is also possible.

Note that in joining ceramics together, it is not necessary to use a brazing material equivalent to silver solder in combination, and it is possible to use the brazing material according to the present invention for joining.

〔Example〕

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.

<First Example> Metal powders of silver, tin, and copper were weighed out in a predetermined mixing ratio and mixed thoroughly. Then, 10 parts by weight of screen oil was mixed with 100 parts by weight of the mixed powder to form a paste. This was coated to a thickness of 60 pm on the surface of a 30 x 15 x 5 mm alumina sintered body 7 (surface roughness 1 to 24 Ra) to form a metallized layer 8. Next, using an electric furnace, it was heated in the atmosphere. The metallized layer 8 was formed by firing at 1100° C. for 10 minutes. A silver solder layer 9 was formed on this sample using silver solder (BAg-1), and was heated in vacuum at 800° C. for 10 minutes to braze the metal 10. The state of the bond at that time is shown in Figure 2, and the results of EPMA of the cross section and surface of the test piece are shown in Figure 1.The shear tensile strength was measured at a loading rate of 0.5 am/sin using a tensile tester. did. As a result, as shown in Table 1, a bonding strength exceeding that of the conventional method was obtained without providing an intermediate layer between the ceramic and the metal. The comparative example is based on the conventional high-melting point metal method, and uses alumina ceramics and is bonded to SS material.

In addition, Table 2 shows the results of a thermal cycle test of test pieces bonded with a brazing material composition of 80% by weight of silver, 10% by weight of tin, and 10% by weight of copper. After heating the test piece at 500°C for 10 minutes,
After repeating the cooling operation for 20 minutes 10 times, the strength at room temperature was measured. Even without the special provision of a stress buffer layer, the strength before thermal cycling shows a small decrease even after cycling.

(Second Example) Metal powders of silver, tin, and copper were mixed in a predetermined ratio, and zirconia ceramics and metal (545C) were joined by the same operation as in the first example, and the strength was measured. In this case as well, as shown in Table 3, high bonding strength was obtained without providing a special intermediate layer between the ceramic and the metal.

Furthermore, similar to the first example, the results of the thermal cycle test were
The brazing material composition shown in the table is 80 parts by weight of silver, 10 parts by weight of tin,
10 parts by weight of silver. From this result, the strength reduction rate before and after thermal cycling in the present invention was smaller than that in the conventional method, and the appearance was also good.

The comparative example is based on the conventional high melting point metal method, and is an example in which alumina ceramics and SS material are bonded.

As can be seen from the above experimental results, in the method for joining ceramics according to the present invention, it is possible to reliably join ceramics and metals even in an oxidizing atmosphere. Further, the metallized layer can be easily formed, the plating process that was conventionally required can be omitted, and the efficiency of the bonding work can be improved. Furthermore, in the present invention, when joining ceramics and metal, there is no need to provide a stress buffer layer between the metallized layer and the metal, and the joining operation can be easily performed. Furthermore, it is possible to bond at a relatively lower temperature than in the past.

〔Effect of the invention〕

Since the present invention has the above configuration, ceramics or ceramics and metal can be reliably joined even in an oxidizing atmosphere.

Table 1 Akira 2 table Akira 4 table

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of a test piece in which metal and ceramics are bonded using the ceramic bonding method according to the present invention;
The figure shows a state in which ceramics and metal are bonded using the ceramic bonding method according to the present invention. l... Parts to be joined (metals to be joined) 2... Ceramics 4... Brazing metal (metallized layer) 5... Tin, copper 6... Silver drawing 8 (no change in content) No. 1 figure 112i! I Procedural entry (method) % expression % 1. Indication of case 1985 Patent application No. 16672
No. 4, No. 2, Title of the invention Ceramics joining method 3, Relationship with the case of the person making the amendment Patent applicant address 1, Kanda Mitoyo-cho, Chiyoda-ku, Tokyo Name Sumitomo Cement Co., Ltd. Representative: Mr. Hikoji 4, Agent address: 1-17-3-5 Toranomon, Minato-ku, Tokyo 105, Date of amendment order: November 26, 1985 (shipment date) 6, ``Drawings'' in the specification subject to amendment "Brief explanation" column and Drawing 7, contents of the amendment As shown in the attached document, contents of the amendment 1) In the fourth line of page 12 of the specification, the phrase "cross-sectional view of," has been replaced with "an electron micrograph showing the metal structure of," ” he corrected. 2) Correct the attached drawings, Figures 1 and 2, according to the attached drawings. Procedural amendment

Claims (1)

[Scope of Claims] 1) A method for joining ceramics, which comprises joining ceramics and members to be joined using a brazing material containing 80% by weight or more of a mixed composition containing silver, tin, and copper. 2) The weight composition range of each component of silver, tin and copper in the brazing material is 70 to 95% by weight of silver, 1 to 25% by weight of tin,
The method of joining ceramics according to claim 1, characterized in that the copper content is 1 to 20% by weight. 3) A method for joining ceramics according to claim 1, wherein a part or all of tin and copper contained in the mixed composition contained in the brazing material are replaced by a metal oxide. .