JPS60255678A - Method of bonding ceramic rotator and metal rotating axis - 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] [Field of Application of the Invention] The present invention relates to a method of joining a ceramic rotating body and a metal rotating shaft, particularly when high strength is required at the joint between the rotating body and the rotating shaft. The present invention relates to a method of joining a ceramic rotating body and a metal rotating shaft, which is suitable for application to.

[Background of the Invention] There are various methods for joining ceramics and metals, but other than mechanical fastening methods and adhesive methods (using inorganic or organic adhesives), bonding methods bond ceramics and metals at high temperatures. At room temperature, thermal stress remains in the joint due to the difference in thermal expansion between the ceramic and metal. Therefore, the strength of the joint is low. On the other hand, with mechanical fastening methods and adhesive methods, no thermal stress remains in the joint, but the strength of the joint decreases at high temperatures. Further, as an example of a mechanical fastening method, as disclosed in Japanese Patent Application Laid-Open No. 55-140771.

There is a method of joining a ceramic rotating body and a metal rotating shaft by shrink fitting based on the difference in thermal expansion between the two.

However, even with this bonding method, the bonding strength is low and it is difficult to use it at high temperatures.

[Purpose of the invention]

An object of the present invention is to provide a method for joining a ceramic rotating body and a metal rotating shaft, which provides high bonding strength even at room temperature and high temperature.

[Summary of the invention]

The present invention heats a ceramic rotating body having a protruding boss concentric with the rotational axis and a metal rotating shaft having a fitting hole having a diameter smaller than the diameter of the boss in a non-oxidizing atmosphere. ,
The boss portion is inserted into the fitting hole, and then the end surface of the boss portion and the bottom surface of the fitting hole are brought into contact and held under isothermal pressure to perform solid phase bonding. That is, at room temperature, since the ceramic rotating body and the metal rotating shaft are shrink-fitted, compressive stress is mechanically applied to the ceramic side. On the other hand, at high temperatures, the mechanical fastening force due to shrink fit is lost, but the end surface of the boss portion is metallurgically joined to the bottom surface of the fitting hole (in-phase joining), and the joining strength is higher than at room temperature.

That is, at room temperature, the bonding strength decreases due to thermal stress, but as the bonding temperature approaches, the residual stress (thermal stress) in the bonding portion decreases, and as a result, the bonding strength improves. Based on the above principle, the bonding method of the present invention can provide high bonding strength in a wide temperature range from room temperature to high temperature.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described with reference to Figure 1.

A rotary impeller 1 made of Si3N and having a protruding boss (diameter 10 m) 2 concentric with the rotation axis, and Cr-Mo
A rotary shaft 3 made of steel and having a fitting hole 4 that is 20 μm smaller in diameter than the boss 2 is heated to 1050° C. in a vacuum atmosphere of 10 → Torr, and Si3N and Cr-M
o Insert the boss 2 into the fitting hole 4 using the difference in thermal expansion with copper. After that, 2 kg per 1mo” of joint area from the axial direction
b/m'' pressure for 4 hours, the end face 2 of boss 2
a and the bottom surface 4a of the fitting hole 4 are solid phase joined. After joining, 1
When cooled from 050°C to room temperature, the fitting hole 4 of the Si3N, Cr-Mo copper rotary shaft 3, which has a larger coefficient of thermal expansion, shrinks, that is, the rotary impeller 1 and the rotary shaft 3 are shrink-fitted. Ru. At this time, thermal stress remains at the joint between the boss end surface 2a and the fitting hole bottom surface 4a.

In this embodiment, at room temperature, when the boss 2 of the rotary impeller 1 is mechanically fastened to the rotating shaft 3, the joint strength is close to that of the Si3N4 base material.

Furthermore, when heated to a high temperature, the fitting hole 4 becomes larger due to thermal expansion and the mechanical fastening force is lost, but the thermal stress remaining at the joint between the boss end surface 2a and the fitting hole bottom surface 4a is small. Become. As a result, the strength of the joint is improved.

In addition, in the present invention, as shown in FIG.
There is a low thermal expansion material Wc between a and the bottom surface 4a of the fitting hole.
Inserting the -6% Go alloy plate 5 further improves the strength of the joint at room temperature. In this example,
A stainless steel plate (0.3 mm thick) 6 is placed between the Wc-6%Go alloy plate 5 and the boss end surface 2a, and a Kovar plate (0.3 mm thick) is placed between the plate 5 and the bottom surface 4a of the fitting hole. 5
mm) 7 are inserted respectively. This is Si3N,
and Wc-6%Go alloy and Wc-6%Go alloy and Cr
- It was inserted for joining Mo steel.

〔Effect of the invention〕

As explained above, according to the present invention, the following effects can be obtained.

(1) It is possible to provide a ceramic rotating body with a metal rotating shaft that has high bonding strength from room temperature to high temperature.

(2) Since the ceramic boss is fitted into the metal fitting hole, machining of grooves for bearings and oil rings becomes easy.

[Brief explanation of drawings]

FIG. 1 shows an embodiment of the bonding method of the present invention, in which 'Si3
FIG. 2 is a sectional view of the joint between the N4 rotary impeller and the Cr-Mo steel rotary shaft, showing another embodiment of the present invention;
FIG. 2 is a sectional view of a joint between a rotary impeller made of i3N and a rotating shaft made of Cr-Mo steel. 1...Rotor wheel made of Si3N, 2...Boss, 2a
...Boss end face, 3...Cr-Mo steel rotating shaft, 4.
... Fitting hole, 4a... Bottom of fitting hole, 5... We-6
Figure ¥3Z diagram

Claims (1)

[Claims] 1. A ceramic rotating body with a protruding boss concentric with the rotational axis and a metal rotating shaft having a fitting hole with a diameter smaller than the diameter of the boss in a non-oxidizing atmosphere. A ceramic rotating body and a metal rotating body characterized by heating the boss part, inserting the boss part into the fitting hole, and then bringing the end face of the boss part and the bottom face of the fitting hole into contact and holding them under isothermal pressure for solid phase bonding. Connection method with rotating shaft. 2. A method of joining a ceramic rotating body and a metal rotating shaft according to claim 1, characterized in that a low thermal expansion material is inserted between the end face of the boss portion and the bottom face of the fitting hole.