JPH0580434B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a composite member made by bonding ceramics and cemented carbide.

<Conventional technology and its problems> When ceramics such as Si ₃ N ₄ and SiC are used as automobile parts, wear-resistant parts, or cutting tools, it is essential to bond them to metal.

However, ceramics such as Si ₃ N ₄ and SiC are difficult to wet with metals, so after metalizing the surface of the Si ₃ N ₄ or SiC or modifying the surface layer by oxidation treatment, etc., under pressure, Bonding was performed in a non-oxidizing atmosphere.

Bonding technology between ceramics such as Si ₃ N ₄ and SiC and metals has been studied on a laboratory scale, but studies on production scale and actual products are still insufficient, and stable and high strength is not yet possible. A viable bond has not been obtained. This is especially difficult for complex shapes because they are easily affected by bulk and shape.

<Means for Solving the Problems> In view of the above-mentioned current situation, the present invention was developed as a result of studies on Si ₃ N ₄ or SiC ceramic composite members that can realize a stable bonding state in any environment and in any shape. This is the culmination of this invention.

That is, the present invention is characterized in that a thin cemented carbide is bonded to one end surface of the Si ₃ N ₄ or SiC ceramic member to aid in bonding to a metal member.

In addition, the cemented carbide in this invention includes WC and TiC.
Co which combines this with hard carbide main components such as
It is a cermet material made of metals such as.

The structure of this invention is to bond ceramics such as Si ₃ N ₄ and SiC with a thin cemented carbide intervening layer.
This is a Si ₃ N ₄ or SiC ceramic composite member, and this composite material facilitates brazing and soldering of the ceramic and metal through the cemented carbide part of the composite member. be.

In addition, this invention uses Si ₃ N ₄ and SiC, which have a low coefficient of thermal expansion.
It is characterized by a combination of cermets and a super hard alloy with the lowest coefficient of thermal expansion among cermets.

By making such a combination, heat is applied during joining such as brazing or Al casting at the site where the composite member of the present invention and the metal member are joined, but at this time, in the case of the composite member of the present invention, Since the difference in thermal expansion between the two composite materials is small, stress generated in the bonding layer between Si ₃ N ₄ and cemented carbide can be reduced.

That is, even if the Si ₃ N ₄ or SiC ceramic is reheated after bonding, there is very little risk of it coming off.

Figure 1 shows Si ₃ N ₄ ceramics 1 as an example of the Si ₃ N ₄ or SiC ceramic composite member A of the present invention.
FIG. 2 shows a state in which the ceramic composite member A of the present invention is brazed and joined to the rocker arm member 3 on-site as an applied example.

In a first embodiment of the present invention, Si ₃ N ₄ or SiC is used to help bond Si ₃ N ₄ or SiC to cemented carbide.
The feature is that an intervening layer of soft metal is provided on the joint surface of SiC and cemented carbide plate to perform the joint.

As a result, the thermal stress caused by the difference in thermal expansion coefficient between the ceramic Si ₃ N ₄ , SiC part, and the cemented carbide part is absorbed by the plastic deformation of the soft metal, thus preventing the occurrence of defects due to thermal stress in the ceramic part. A strong bonding layer is obtained.

Figure 3 shows Si ₃ N ₄ 1 and cemented carbide plate 2 in intervening layer 4.
This figure shows an example of a ceramic composite member B in which the following are bonded together.

In this case, the intervening layers include Al, Cu,
The material should be selected from soft metals such as Ni, Al-Si, Ti, and Nb.

Furthermore, as another more preferable embodiment of the present invention in which cemented carbide and Si ₃ N ₄ or SiC are bonded, Si ₃
Or after sputtering the surface of SiC, Ti,
This is a method of coating with an active metal such as Nb or Zr, and then layering the soft metal such as Al.

The reason why the active metal is coated on the Si ₃ N ₄ and SiC surfaces in advance is to further ensure the bonding with the cemented carbide since the bonding interface between these ceramics has poor reactivity with metals.

Both of the above two embodiments can be joined by heating under pressure or with no load.

<Example> This invention will be explained below with reference to Examples.

Example 1 After polishing the end face of Si ₃ N ₄ with an outer diameter of 30 mm and a thickness of 10 mm using a #200 diamond grindstone, it was heated in a furnace under vacuum.
The furnace was evacuated at 10 ^-6 Torr, and then Ar gas was introduced so that the pressure inside the furnace was 10 ^-3 Torr, and sputtering was performed.

Furthermore, the Si ₃ N ₄ surface was coated with Ti to a thickness of 0.5 μm.

Next, this Ti-coated Si ₃ N ₄ and an outer diameter of 30
Cemented carbide plates with a thickness of 2 mm and a thickness of 2 mm were put together, and an Al plate with a thickness of 0.5 mm was inserted between them as an intervening layer.

In this state, heating was performed under no pressure at 660 to 700°C in an Ar flow, resulting in a strong bonded body with a bonding shear strength of 15 Kg/mm ² .

Thereafter, the joined body was cut into a 20 mm square shape and brazed to a rocker arm using Ag solder. No cracking occurred in the joint due to thermal stress.

The Si ₃ N ₄ composite exhibited high performance as an automobile part.

Example 2 The Si ₃ N ₄ composite member obtained by the method shown in Example 1 was used as a tapepet and brazed to a steel part. In this case as well, no cracks were observed at the joint.

This Si ₃ N ₄ tappet has excellent wear resistance and has a lifespan more than 10 times that of conventional steel tappets.

Example 3 SiC with an outer diameter of 30 mm and a thickness of 20 mm, an outer diameter of 30 mm and a thickness of 5
Cemented carbide having a diameter of 1 mm was bonded using the method of Example 1 with the addition of a pressure of 100 Kg/cm ² .

When the SiC composite member was Cu-brazed to the piston head, no thermal stress damage was observed in the joint due to brazing. When this jointed part was attached to an automobile engine testing device as an engine piston head and operated continuously, it was found that it could be used without fear of damage.

Example 4 The end face of Si ₃ N ₄ with an outer diameter of 30 mm and a thickness of 20 mm was polished with a #200 diamond grindstone, a Ni plate with a thickness of 0.5 mm was interposed, and a cemented carbide alloy with a thickness of 1 mm was combined, giving a yield of 100 Kg/cm ² A composite member was obtained by heating at 900°C for 30 minutes under pressure. The atmosphere at this time was a vacuum of 1×10 ^-5 Torr.
When this composite member was brazed with a heat-resistant alloy (Ni-based) using silver solder, a joined body with no cracks in the composite part was obtained. When a test piece with an outer diameter of 10 mm was cut out from the joined body and its tensile strength was measured, both the composite part and the brazed part with the heat-resistant alloy showed a high strength of 10 Kg/mm ² or more.

<Effects of the Invention> As detailed above, the ceramic composite member of the present invention can be easily bonded to metal members through the cemented carbide layer, so it can be used as automobile engines, wear-resistant parts, or cutting tools. In this case, it became possible to take advantage of the excellent properties of ceramics, and as a result, it became possible to use them for a long time.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing an example of the ceramic composite member of the present invention, Fig. 2 is an explanatory diagram showing the state in which the composite member of the present invention is brazed to a rocker arm, and Fig. 3 is an explanatory diagram showing an example of the ceramic composite member of the present invention with an intervening layer. FIG. 2 is an explanatory diagram showing a composite member of the present invention in which hard metals are joined. 1...Ceramics, 2...Cemented carbide, 4...
Intervening layer.

Claims (1)

[Claims] 1. A composite member in which a ceramic member made of Si ₃ N ₄ or SiC and a cemented carbide plate are bonded, and a bonding layer between the two is Al, Cu, Ni, Al-Si, or Ti. ,
A ceramic composite member characterized by interposing a soft metal plate of Nb. 2. In the composite member according to claim 1, a sputtered active metal layer of any one of Ti, Nb, and Zr is provided on the surface of the ceramic member in advance, and then the soft metal plate is interposed. Characteristic ceramic composite parts.