JPS58140381A - Metallization of silicon nitride sintered body surface - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] Silicon nitride sintered bodies can be used as high-temperature mechanical parts, due to their excellent heat resistance, thermal shock strength, mechanical strength at high temperatures, and abrasion resistance.
In particular, it has attracted attention as a component of internal combustion engines, and for example, it has the high strength required when firmly joining dissimilar materials such as metal by brazing as a chip for the sliding part of a rocker arm. There was a production of metallized boxes with Kli.

This is because the silicon nitride sintered body has an extremely low coefficient of thermal expansion of 12 x 104, which greatly contributes to the heat resistance such as the thermal shock strength.
x 10 and loud noise (there is also a large difference between high aluminum (7 j Furthermore, when used at high temperatures, a large difference in thermal expansion occurs in the case of a round shape, which reduces the bonding strength with different materials.

The present invention has succeeded in establishing a metallization method for the surface of a silicon nitride sintered body that exhibits a bonding strength of 1% between dissimilar materials, and the surface of the silicon nitride sintered body has wrinkles. The mold is made by forming one layer of a reaction layer made of a metal highly reactive with silicon and a buffer layer made of a highly malleable metal by a material vapor deposition method.

Therefore, the reaction layer formed on the surface of the electrified bare hook body 0 of the base is made of a metal that is reactive with silicon nitride, such as Tj # Cre Mo # Zr @ Hf a
W and alloys containing these, such as Ni r Cr, are selected, but the film thickness is due to the rigidity of these metals, and the reason why the thermal coefficient is significantly higher than that of the base electrified silicon sintered body. It is desirable to make it as thin as possible in order to shorten the time required for vapor deposition, but if it is too thin, the entire layer will react, making it impossible to obtain the necessary bonding strength between one stroke of the buffer layer, resulting in rounding, and less Common tooiviut is necessary,
Beyond that, the bonding strength increases roughly according to the film thickness.
It slows down from around oX, and excessive film thickness not only deteriorates durability due to the reasons mentioned above, but also requires a long time for vapor deposition, so the maximum thickness is about 10,000i.
A range of 000X is preferred.

Next, the buffer layer formed on the surface of the reaction layer is to prevent brazing with different materials and to collect the difference in thermal flux between the bonding layers, so it is necessary to use a metal with high malleability, such as a metal with high malleability. Cu HAl tmu+Ag and alloys that combine these are used, and Ni, which has a slightly inferior malleability but has high wettability with brazing material, can also be used, and from the viewpoint of price, Cu * Nl *
AI is most suitable for practical use, and for the reasons mentioned above, it is desirable that the 7O film be thicker than the reaction layer, but if it is lost too much, the thermal expansion of this buffer layer itself will degrade the bonding strength, and it will also cause problems with vapor deposition. If it takes a long time and the testability decreases, but if it is too thin, the buffer layer and the reaction layer may be overlaid on the lower reaction layer using the method. and the combination K of those metals.

In addition, the reason why we have decided on the physical vapor deposition method KIfIi as a means for forming the reaction layer and the buffer layer in this work is that the material and film thickness of these inner layers can be freely determined, and this method The reaction layer and the buffer layer are formed using a physical vapor deposition method. Therefore, a metallization paste, which has conventionally been used as a means of forming a metallized surface of seeds, is screen printed on the surface of the substrate and then non-oxidized. The disadvantage of the metallization (thick film) method, which involves heating in a static atmosphere, is that the metallized surface formed on the substrate is made of a rigid refractory metal mainly composed of tungsten or W, and the film thickness is also 10%.
Because of the thickness of the film, it is possible to solve at once the problem of low reliability fk, which makes it impossible to compensate for differences in heat and heat of different materials.

As a physical deposition method, there are vacuum deposition, ion beam deposition, and sputtering, and any of them can be used.

Example 1 Average grain*/p of 81sNa l) *F' Part by weight and average grain size ajμ of the total cost! The mixed powder consisting of JOxlOXjmO and JOxlOXjmO is formed into a plate shape, kept at ty'zoc in a nitrogen atmosphere for a period of time, and then sintered under pressure to obtain a J( After polishing one main surface made of Itlo- to a surface roughness of a/7 to a#tμ&, cleaning (neutral detergent and running water) - water replacement with acetone - cleaning (/, / , "' / ') dichlorethane and acetone) - with the addition of a drying cleaning process, and this is then processed using a vacuum evaporation machine (Japan Vacuum Technology @ EB
TI was selected from the metal shown above, which was heated to 100° C. and subjected to the above polishing process, in a vacuum chamber of V-40H). Regarding a sample in which Cu was selected from a metal with high malleability while maintaining a vacuum degree of , it was similarly melted by electron beam heating, and a buffer layer with a thickness of l# was formed on the reaction layer made of T. Silicon nitride base
In order to examine the bonding strength of the metallized surface consisting of the reaction layer and the buffer layer to the thin body, the metallization direction was formed into a 111 m circular pattern by photoetching, and the end surface was polished to a flat surface. The results of a tensile test in one perpendicular direction are shown in the first table.
′ shown in the table.

However, the metallized surface consisting of the above reaction layer and buffer layer is
The reaction layer due to T1 is O film thickness K1 shown in Table 1.
After each deposition, a Cu buffer layer was deposited to a thickness of lμ to form a circle.

fA/* From Table 2, if the reaction layer on the metallized surface is Ti with the thickness of each layer and the buffer layer is Cu with a fixed thickness of lμ, then the reaction layer thickness is jOλ (too'). (hereinafter 0Illll thickness is estimated by rounding deposition time), the bonding strength with the substrate expressed by the tensile strength is so low that it is not practical, and it increases sharply from iooλ as the film thickness increases. It was shown that the strength of the shelf that peels off from the bonded part is suitable for the bonding strength of 10001, but it has been shown that the thickness of the film is preferably 10,000 mm, taking into consideration the reasons mentioned above.

EXAMPLE The reaction layer in the metallization was identified at T1 with a film thickness of JoooA, and the buffer layer was made of a malleable metal of Cu and G. Table 1 shows the results of the tests. However, when the buffer layer was made of AI, a solder for aluminum manufactured by Nippon Superior Co., Ltd. called Altsul 41LjI (trade name) was used as the brazing material.

7/' // ,, /”' JI J From both tables, the buffer layer o*thickness is Cu, N1, A
I (D) In both cases, the effect is expressed from ajμ, and the bonding strength is approximately proportional to the film thickness, but there is a tendency to saturate from the degree of control.

夷-Example J In addition to T1, silicon nitride and reactive O
Zr * Cr * i, which is known as a hard metal, and alloys containing them are represented by Ni and Cr; on the other hand, Cu *, which has great malleability as a mild layer and has good wettability with Ushida wood, Using inexpensive Cu and N1 from NieAu, AgO metals or alloys containing them, the former reaction layer is made into a thinner layer.
The results are shown in Table 3.

// From Table 3, Zr s Cr * Mo e Ti l
The metallized surface formed by the reaction layer consisting of Nl.Cr and the 1ikIII layer consisting of sCu t Ni exhibits satisfactory tensile strength in both combinations, with Ti a Zr as the reaction layer and Cu as the buffer layer. It was confirmed that particularly excellent effects were exhibited when Qin was used.

As described above, a reaction layer made of a metal or alloy highly reactive with silicon nitride and a buffer layer made of a highly malleable metal or alloy are formed on the surface of a silicon nitride sintered body by physical vapor deposition. tCharacteristicsThe method for metallizing the surface of a silicon nitride sintered body of the present invention allows the material and film thickness of the reaction layer and buffer layer to be freely determined according to the purpose, so that The heat between the extremely thin reactive layer bonded to the solid material and other materials that are highly malleable and bonded.
It consists of a buffer layer with a film thickness sufficient to absorb one expansion difference, and is firmly bonded to other O metals by brazing, making it possible to obtain a highly durable metallized surface.

Note that the material that can be joined by sealing is not limited to metals, but may be other ceramic sintered bodies such as oxides or carbides with a metallized surface provided on the surface. Although it is difficult to divide the core body into more parts and join the composite sintered bodies together, it is effective for combining different materials with different thermal coefficients.

Claims (1)

[Claims] A reaction layer made of a metal or alloy highly reactive with the electrified silicon and a buffer layer made of a highly malleable metal or alloy are formed on the surface of the silicon nitride sintered body by a blanket vapor deposition method. A method for metallizing the surface of a silicon nitride sintered body.