JPS59164675A - Ceramic bonding method - 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] The present invention relates to bonding force V of ceramics.

In recent years, ceramic materials have come to be considered as new structural materials. 4? Research is progressing to develop materials with excellent i-impact resistance or thermal shock resistance. In terms of JL, for example, applications for automotive parts such as engine parts such as screws, valves, and cylinder lights, and rotor parts such as gas turbines and turbochargers are being considered.

The ceramics used for these parts are heat resistant.
, 1fliAlthough it exhibits excellent characteristics such as monocorrosion and wear resistance, it has the disadvantage of poor workability because the ceramic is mainly formed by sintering. Therefore, the current situation is that the scope for expanding the use of Ceramitsuge is still limited.

Therefore, various methods for joining ceramic members have been developed, such as brazing methods such as active metal method and oxide method, and high energy density heat sources such as laser beams. There are joining methods that involve direct melting.

Among these methods, in the brazing method, the shape of the joint can be changed freely.
ff JII! It has the advantage that it can be applied over a wide range of areas, but it has the disadvantage of low productivity because it requires long processing times in a vacuum or special atmosphere when soldering. .

On the other hand, joining methods that directly melt ceramics have drawbacks such as being limited in the types of ceramics that can be used and requiring welding in a furnace to prevent cracking due to localized heating.

Therefore, the present inventors reexamined the conventional joining methods, and
Various ceramic members and various metal members were joined by friction welding, and as a result of various studies, we found that joints between aluminum and its alloys and silicon nitride, zirconia, silicon carbide, and alumina were stable. It has been discovered that the bonding strength is greater than that of the material metal. It has also been found that the mr between magnesium and its alloys and silicon nitride, zirconia, and magnesia determines good bonding strength.

This friction welding method has traditionally been used to join metals together, and it is possible to work in the atmosphere, is good for work, has low equipment costs, and takes a long time to weld. It has the advantage of being short and highly efficient, and because only the joint surfaces are heated, energy efficiency is high and operating costs are low.

This invention was made based on the knowledge described in -1-, and it is possible to use a metal or an alloy thereof that fully utilizes the advantages of two frictional contacts and satisfies the predetermined conditions for ceramic members to be used as a ceramic member. The object of the present invention is to provide a method that can bond ceramics together with high joint strength by interposing them between the bonding surfaces with ceramic 7H1 (materials).

That is, when joining ceramic members (including cermet members) together by friction welding, the present invention provides a method for bonding ceramic members (including cermet members) to each other by friction welding. The feature is that aluminum or an alloy thereof, or magnesium or an alloy thereof is interposed between the metal surfaces.

It is generally known that aluminum and its alloys, magnesium and its alloys, and ceramics have very poor Ih, S resistance. for example,
This is why, when aluminum is die-cast using a die-casting machine or the like, the surface of the aluminum melt 1j is coated with vacated silicon or the like on the surface of the aluminum melt 1j.

However, this joining becomes possible if the two are slid at high speed while applying pressure using the friction welding method. The reason for this has not yet been clearly determined, but because the bonding surfaces between the two slide at high speed, surface layers such as oxides on the metal bonding surfaces and gas adsorption layers on the ceramic bonding surfaces are peeled off. It is thought that the clean surfaces are exposed and come into contact with each other, and that the metal blends well with the unevenness of the cleaned ceramic bonding surface due to the application of pressure, increasing the contact surface area between the clean surfaces. For this reason, it is thought that a reaction or diffusion phenomenon occurs between the ceramic and the metal at the contact surface, and a chemical force acts on both bonding surfaces to bond them.

-1; Pursuing the phenomenon further, for example, silicon nitride (
Siq N4 ) and aluminum (Au), the standard free energy of formation (G
Comparing c) with the standard free energy of formation (GM) for aluminum nitride formation, the absolute value of aluminum is larger, and the force of aluminum nitride is more stable than that of silicon nitride. This suggests that silicon nitride and aluminum may react.

In order to confirm the possibility of this reaction, silicon nitride powder and aluminum powder were mixed and molded and heated to 1200°C. All of the silicon nitride decomposed17 and aluminum nitride was produced instead. I confirmed that there is.

However, since the welding temperature during friction welding is below the melting point of aluminum and is a short-time heating phenomenon, it cannot be equated with the above reaction. The bonding strength has been obtained to be one level higher than the strength of the base material of aluminum. Also, magnesium reacts with certain types of ceramics in the same way as aluminum.

This development 1!11 is based on the fact that, as mentioned in -1-, aluminum or its alloys, magnesium or its alloys, and ceramics can be easily joined by friction welding and have high strength.
This method was developed by focusing on the ability to do 11 in (1), by interposing aluminum or its alloy, or magnesium or its alloy between the joining surfaces of both ceramic members, and firmly joining the ceramic members together by friction welding. It has some characteristics.

In this invention, the ceramic constituting the ceramic member is a ceramic material in which the main components are a metal element and N, C, and O elements, which are the main nonmetal elements, each in a single combination or in a combination of two or more,
Specifically, S, which is a typical structural ceramic material,
iC.

Si3N, PSZ (partially stabilized zirconia).

Au, 03. MgO, Sialon (S i3 N4-A
u203) i is used. This bonding of ceramic members can be applied not only to ceramics of the same type, but also to ceramics of different types, such as silicon nitride and alumina.

On the other hand, as a method of interposing aluminum, for example, between the joint surfaces of ceramic members, one of the ceramic members can be used in advance! ! 18! Aluminum is joined to the joint surface of the parts by friction welding, and after the end face is processed, it is friction welded to another ceramic member. Or, the joint surface of one ceramic member is melted or ion-blated. There are methods such as coating aluminum using the following methods, but the former is not very preferable because the machining surface becomes complicated, and the latter is not very economical from the viewpoint of the processing process because the processing to coat the aluminum is expensive. Not.

Therefore, as a method for frequently interposing aluminum, it is more preferable to use an aluminum foil, sandwich the aluminum foil between the joining surfaces of the ceramic members, and join them by one friction welding.

In this method, aluminum foil may be bent to match the shape of the end of one of the ceramic members and fixed by a method such as covering the joint surface in a gap shape.

This aluminum foil is sandwiched between a rotating ceramic member and a fixed ceramic member during friction welding, and as it rubs against the respective joint surfaces, it generates heat and plastic flow, and some of it is Extruded toward the outer circumference of the surface. In this process, the oxide layer on the surface of the aluminum foil and the gas adsorption layer on the surface of the ceramic are removed from the bonding surfaces, and the bonding end surfaces become clean surfaces and are brought into contact with each other to perform bonding. After this, the friction welding is completed by stopping the rotation.

In normal friction welding of metals, the metal is softened and plastically deformed due to the frictional heat generated at the joining interface during friction welding. Therefore, even if the parallelism of the pressure contact surfaces of both metal joint members is not sufficient due to factors such as processing accuracy of the metal joint members, deviation during chucking, or machine precision, the joint surfaces will undergo plastic deformation and the entire friction surface will be This results in a good bonding.

However, since ceramics hardly undergo plastic deformation, in friction welding between ceramics, as shown in Figure ff11, the bonding surfaces 3.4 of the ceramic members 1.2
The thickness of the aluminum foil interposed between the bonding surfaces is 3.4
If the gap between the ceramics and the aluminum foil is smaller than the maximum gap of 2,079,776 mm, some of the ceramic parts may be 5°6
They will be in direct contact with each other. In the ceramic portions 5 and 6, the ceramics are in the same state as repeatedly colliding with each other at high speed, so the ceramics break or crack, resulting in a significant decrease in strength.

Therefore, the thickness of the aluminum foil is at least 20797 mm
It is particularly desirable to make it larger than 76 sentences. Furthermore, in order to bond the ceramic 1.2 and the aluminum foil with sufficient strength, it is desirable to sufficiently plastically deform the aluminum foil and clean the bonding surface. Therefore, the aluminum foil must have a certain thickness for sufficient plastic deformation. The inventors investigated the bonding strength by varying this clearance Δρ and the thickness of the aluminum foil11', and found that if the thickness of the aluminum foil was made more than twice the thickness of 2079776mm, cracking would occur in the ceramic. It was confirmed that sufficient bonding strength could be achieved without causing any problems.

Examples of the present invention will be described below.

Example 1 A round bar made of commercially available pressureless sintered silicon nitride with a diameter of 30 mm and a length of 100+ nm was used as the ceramic member, and an aluminum foil of 0.25+ nm J was used as the aluminum foil interposed between the bonding surfaces of both ceramic members. I used pure aluminum foil.

When performing friction welding, a brake-type friction welding machine is used, and as shown in FIG. Aluminum foil 8
was bent to form a cap shape and fitted onto the end of the ceramic member 1. At that time, it was left covered without fixing it! It was set to 1. Also, ceramics on the other hand! 4
The J member 2 was placed on the rotating chuck 9, and friction welding was performed under the welding conditions shown in Table 1.

Table 1 Next, when we observed the cross section of the joint after pressure 1)x using an optical microscope, we found that there were some areas where there was no aluminum on the outer periphery of the joint surface, but aluminum foil remained on almost the entire surface. At the same time, it was found that the aluminum layer and the ceramic were in good contact with each other, with no voids observed at the interface. An example of photographic observation using this optical microscope is shown in FIG.

Next, in order to check the joint strength of this joint, we
j test was conducted. As a result, the average bonding strength was 7,
8 kgf/mm', and the fracture location was mainly at the joint of the aluminum foil, but also partially at the ceramic base material. Although this bonding strength did not reach the strength of the base material of ceramics, it approximated the strength of the aluminum foil base material and was comparable to the bonding strength of conventional brazing methods.

Example 2 As the ceramic member, the same commercially available pressureless sintered silicon nitride as in Example 1 was used, but as the aluminum foil,
Thickness 0, 03111m, 0, 1mm.

Four types were used: 0, 25 mm, 0, and 5 mm.

First, the ceramic members were each attached to a brake-type friction welding machine so that they could be pressed together, and then both joint surfaces were brought close to each other and brought into contact, and the clearance Δ was determined using a thickness gauge. Thereafter, aluminum foils of various thicknesses were taken in the same manner as in Example 1, and pressure welding was performed under the same pressure welding conditions. After welding, we examined the joint strength of the joint, and the results shown in Figure 4 were 1'.
I got 1. In the figure, the horizontal axis shows the clearance Δ, the vertical axis shows the thickness of the aluminum foil, and the joint quality of each combination σ is shown. ○ indicates good bonding (bonding strength ≧5 kgf/mrn'), Δ indicates a bonded portion (bonding strength ≦1 kgf/nun2), and X indicates poor bonding (ceramic cracking).

As is clear from the figure, if the thickness of the aluminum foil is made thinner than twice the clearance Δ (below line A in the figure), the ceramic will crack during bonding, or even if pressure welding is possible, problems will occur during pressure welding. Due to the cracks, the tensile strength becomes 1 kgf/mm2 or less, and the ceramic base material breaks. On the other hand, if the aluminum foil is made to have a clearance that is more than twice the clearance of Au (from line A in the figure), the tensile strength will be 5 kgf/llll112 or more, which indicates sufficient joint strength. .

In addition, although the example described in 1-1 shows the case where ceramic members made of the same material were joined together, good results were also obtained in joining different types of ceramic members. In this case, SiC, Si3 N4,
PSZ and Au203(7) can be joined by friction welding with aluminum or its alloy interposed,
Magnesil is used for joining Si3N4゜PSZ and MgO.
It was possible to perform friction welding by interposing , or an alloy thereof. Furthermore, it was possible to join MgO and AJJ, 03 even when the joining surface of MgO was covered with magnesium foil, the joining surface of A4203 was covered with aluminum foil, and both members were friction-welded.

As is clear from the explanation below, according to this invention,
When joining a ceramic member and an old ceramic part, aluminum or an alloy thereof, or magnesium or an alloy thereof is interposed between the joint surfaces of both ceramic members, and friction welding is performed to bond the ceramic members well. It is said that it is possible to make highly efficient and reliable joints.
It has a great effect.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing the clearance generated at the bonding surface between ceramics and ceramics, Fig. 2 is a schematic diagram showing an embodiment of the present invention, and Figs. 100x and 4x, respectively, showing the cross section of the joint
．． FIG. 4, which is a micrograph at a magnification of O0, is a graph showing the relationship between the clearance Δ and the thickness of the aluminum foil on the bonding strength. 1.2... Ceramic member, 8... Aluminum foil. ! 11th edition applicant 11san Jidosha Co., Ltd. agent patent attorney Ko'a! IΔβ N3 diagram (a) (b). Figure 4 Clearance Δ1 (mm)

Claims (1)

[Claims] (1) A method for joining ceramics, which comprises interposing aluminum or an alloy thereof, or magnesium or an alloy thereof between the joining surfaces of both ceramic members when joining the ceramic members by friction welding.