JPH0339991B2 - - Google Patents

Description

[Detailed description of the invention]

"Industrial Application Field" The present invention is suitably used in the field of firmly bonding ceramics and metals. ``Prior art'' Ceramics and metals are usually joined by brazing, but since ceramics and metals have significantly different coefficients of thermal expansion, this large expansion difference causes considerable strain in the vicinity of the joint. It will remain. This distortion causes destruction of the fragile ceramics. To prevent this, low expansion metals such as W and Mo, whose coefficient of thermal expansion is close to that of ceramics, are interposed as a buffer layer between the ceramics and metals to be bonded, or these low expansion metals are bonded.
A method of bonding by interposing a cladding material made of Cu as a buffer layer has been proposed (proposed in Utility Model Application Publication No. 160533/1983, ``Ceramic-metal bonding structure''). "Problems to be Solved by the Invention" However, in the former of the above conventional techniques, Ni plating is applied to the joint surface to improve the wettability of the silver solder used as a joint material, but the plating adhesive part There is a risk of peeling due to deterioration, and there is an inherent quality instability factor. Furthermore, the latter has the disadvantage that not only the combinations of metals that can form the cladding material are limited, but also the usage conditions of the bonded structure are limited due to the lack of bonding strength of the cladding material itself. "Means for Solving the Problems" The present invention solves the problems of the above-mentioned prior art, and its means include forming a buffer layer between one or more low expansion metals and one or more low Young's modulus metals between the ceramic and the metal. This is a bonding structure between ceramics and metal, in which the buffer layer has a thickness of 0.04 to 0.4 times the longest width of the bonding surface, and the bonding means is brazing. Low expansion metals include W-Ni alloy, W-Cu alloy, W-Cu-Ni alloy, W-Ni-Fe alloy,
A metal containing W as a main component, such as a W-Fe-Ni-Cr alloy, or a metal containing Mo as a main component is suitable. Cu, Ag, Ni, Fe-Ni42 as low Young's modulus materials
% alloy, KOVAR, SUS403, etc. are good. The buffer layer is a composite layer consisting of two or more layers of one or more low expansion metals and one or more low Young's modulus metals.
If the thickness of the entire layer is less than 0.04 times the longest width of the bonding surface, the bonding strength will be poor, and if it exceeds 0.4 times, no improvement in effectiveness can be expected, and there is a high possibility that the buffer layer will be deformed by impact during use. Become. The coefficient of thermal expansion of a low expansion metal is that of the ceramics to be joined.
It is desirable that it be 1.7 times or less. In the present invention, ceramics, the above-mentioned buffer layer, and metal are all brazed and joined at the same time. "Function" Two or more types of buffer layers consisting of one or more low expansion metals and one or more low Young's modulus metals alleviate the strain at the joint, and the thickness of the buffer layer is limited to the above range when brazing and joining. This results in high bonding strength. "Example" Prepare the ceramics shown in Table 1, the buffer materials shown in Table 2, the brazing filler metals shown in Table 3, and the precipitation hardening stainless steel of JIS standard SUS630.
The combinations shown in the table were arranged as shown in FIG. In the figure, 1 to 5 are cushioning materials, 6 to 11 are brazing materials,
Reference numeral 12 indicates ceramics, and reference numeral 13 indicates precipitation hardening stainless steel, both of which have a disk or cylinder shape with a diameter of 15 mm. After the ^above arrangement, the I-
The results of measuring the ZOD impact value are also listed in Table 4.
The I-ZOD impact value is as shown in Figure 2.
The precipitation hardening type stainless steel 13 was fixed, and a point P 10 [mm] from the bonding surface of the ceramics 12 was set as the point P.

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[Table] As can be seen from Table 4, the joint structures 1 to 14 of the present invention
and Nos. 21 to 26 all had an impact value of 8 [Kg cm] or more, but the joint structures Nos. 15, 16, and 19 were outside the scope of the present invention.
and 20 had a low impact value of less than 8 [Kg·cm], and in joint structures 17 and 18, which were also outside the range, the cushioning material was deformed when the impact value was measured. "Effects of the Invention" According to the present invention, a bonded structure with extremely high bonding strength can be obtained, and can be applied to various engine parts such as intake and exhaust valves of internal combustion engines.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a bonding structure between ceramics and metal according to an embodiment of the present invention. Figure 2 is I
- It is a side view for explaining the ZOD impact value measuring method. 1-5...buffer layer, 6-11...brazing material, 12
...Ceramics, 13...Precipitation hardening stainless steel.

Claims (1)

[Claims] 1 In the case where ceramics and metal are bonded by interposing one or more low expansion metals and one or more low Young's modulus metals as a buffer layer, the buffer layer has a thickness of 0.04 to 0.4 times the longest width of the bonding surface. , a bonding structure between ceramics and metal, characterized in that the bonding method is brazing.