JPH01100071A - Joining of ceramic shaft and metallic part - Google Patents

Abstract

PURPOSE:To prevent the displacement and escape of a joint part of a ceramic shaft and a metallic part caused by rotation, by forming a recess on the outer circumference of a joint end on a ceramic shaft, pouring molten metal into a gap between the outer circumference and an inner circumference of the shaft hole and solidifying the metal. CONSTITUTION:The fitting surface of a joint part of a ceramic shaft 1 is provided with two recesses 3 symmetrically in axial direction to prevent the escape and rotation of a metallic part. The recess is formed by grinding with a diamond grinding wheel dressed to a radius R of about 3.5mm while feeding the wheel in a direction perpendicular to the axis. The recess 3 has a cross-section consisting of a circular spherical groove. A ring 6 made of a low-thermal expansion metal consisting of an Ni-based alloy is inserted and fitted to the shaft 1. A molten metal 5 consisting of a silver solder is heated at about 750 deg.C, filled into the space of the fitted face and solidified by cooling. The ring 6 is welded to a metallic shaft 4 at the joint face 7 by electron beam welding.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of joining a ceramic shaft and a metal member.

[Prior Art] Conventionally, when joining ceramics and metal members, a method has often been adopted in which the ceramics are first plated with metal or metallized, and then the ceramics and the metal members are joined by brazing. There is. In particular, when coupling ceramics and metal members, coaxiality between the ceramics and metal members is often strictly required. If the part where the ceramic and metal parts are to be joined remains on the firing surface, it is difficult to ensure coaxiality between the two, so it is recommended that the parts where the ceramics and the metal parts are joined be polished with a diamond grindstone. He is a connoisseur. On the other hand, when the ceramic surface is polished and metal plated, the adhesion strength between the ceramic and the metal decreases. In order to improve this point, Japanese Patent Application Laid-Open No. 60-155578 provides a groove with a fired surface that has not been polished, forms a metal layer on the joint including the groove, and fits a metal member. There is a disclosure that a ceramic and a metal member are joined by fitting and then brazing the fitting portion.

Further, Japanese Utility Model Application Publication No. 61-57101 discloses that a recess is formed on the outer circumferential surface of the coupling shaft, and a chip made of a material having a higher coefficient of thermal expansion than the metal rotating ring is welded and inserted into the recess.

[Problems to be Solved by the Invention] In conventional bonding methods, when the temperature of the bonded portion becomes high, the bonding force decreases significantly. Furthermore, there is residual stress in the bonded portion, which reduces the bonding force. Another problem is that the strength of the joint is low.

The present invention has been made in view of these conventional problems, and an object of the present invention is to improve the prevention of slippage and pull-out due to rotational force at the joint between ceramic and metal members.

[Means for Solving the Problems] The method of joining a ceramic shaft and a metal member of the present invention provides a method for joining a ceramic shaft with a ceramic shaft having a small number of recesses (one in each case) on the outer circumferential surface of the annular joint end. It is inserted into a metal member having a shaft hole to be fitted, and the outer peripheral surface of the upper end of the shaft is fitted into the shaft hole, and the outer peripheral surface of the joint part of the ceramic shaft and the inner periphery of the shaft hole of the metal member are inserted. The ceramic shaft and the metal member are joined by injecting and solidifying molten metal into the gap formed between the ceramic shaft and the metal member.

The recess may be a spherical recess groove having an arcuate cross-section. Further, the recessed portion may be a groove having an arc-shaped cross section parallel to the axis of the axial joint end. This concave portion has a shape that can be processed in one pass using a grindstone which has a disk shape in both the radial and axial directions of the shaft axis and whose grinding surface is dressed with a flat surface or a curvature. By injecting molten metal into this recess and solidifying it, the shape is such that the shaft can be prevented from being pulled out and prevented from relative rotation at the same time.

In this case, the molten metal to be injected is preferably one that does not adhere to ceramics and has a high adhesive strength to metal members. As the molten metal to be injected, silver solder, copper-zinc alloy, etc. can be used. It is preferable that the metal member into which the ceramic shaft is inserted has a small coefficient of thermal expansion so that the adhesive force with the molten metal does not decrease at high temperatures. On the other hand, if the injected molten metal has a large coefficient of thermal expansion, the metal member can be fitted and maintained even if its coefficient of thermal expansion is large. A 5Cr40 alloy can be used as the metal member.

The gap formed between the outer peripheral surface of the joint part of the ceramic shaft and the inner peripheral surface of the shaft hole of the metal member is the part where molten metal is injected to adjust the misalignment and inclination of the shaft center, and the gap is 300 μm.
It is preferable that it is below m.

[Effects and Operations of the Invention] With the above-described structure, the present invention prevents handling and relative rotation at the joint between the ceramic shaft and the metal member, and fills the gap between the ceramic shaft and the metal member. There is little residual stress because it is not bonded to the metal. Therefore, the bonding force is large and there is little decrease in the bonding force even at high temperatures.

Furthermore, since this bonding method does not require adhesion between ceramics and metal, metallization treatment on the bonding surfaces of ceramics is not necessary. Therefore, since it is only a simple grinding process, it is an inexpensive joining method.

[Example] The present invention will be explained below based on Examples.

(Example 1) FIG. 1 is a sectional view illustrating a joint between a ceramic shaft and a metal member in this example.

The joint between the ceramic shaft and the metal member is created by injecting molten metal 5 into the gap between the metal member 2 and the recess 3 formed on the outer peripheral surface of the ceramic shaft 1 made of silicon nitride. It's joined. The metal member 2 is made up of a heat-resistant ring 6 fitted to the outer peripheral surface of the ceramic shaft 1 and a heat-resistant metal shaft 4, which are integrated by welding. Figure 2 shows 8-8 in Figure 1.
AIli! A cross-sectional view of the figure is shown.

On the fitting surface of the joint portion of the ceramic shaft 1, two recesses 3 are formed symmetrically in the axial direction to prevent handling and to prevent rotation. This recess 3 is formed by grinding. It was ground using a diamond grindstone which had been dressed in advance with a radius of R3,5IIIll and was fed in a direction perpendicular to the axis. This recess 3 is
As shown in the sectional view of FIG. 2, the cross-sectional shape is a spherical four-part groove with an arcuate shape. This ceramic shaft 1 has Ni
A ring 6 made of a base alloy low thermal expansion metal (Incoloy 903) was inserted and fitted, and the molten metal 5, which was a silver brazing filler metal, was heated to 750° C. and injected into the gap of the fitting surface to fill it, and then cooled and solidified. After that, the ring 6 is attached to the metal shaft 4 (the material is 5C).
r40) at joint surface 7 by electron beam welding.

In the above joining method, the ceramic shaft 1 and the silver brazing material of the molten metal 5 are not bonded together, and the molten metal 5 is only bonded to the metal member 2. Therefore, to prevent disconnection between the metal member 2 and the ceramic shaft 1 and to prevent relative rotation between the ceramic shaft 1 and the metal member 2, it is possible to This is done by filling and holding silver brazing material.

The thus joined bodies were placed in a furnace kept at 400°C and tensile tests and rotational forces were measured therein.

As a result, it had a tensile strength of 5 kQf and a rotational torque of 4 kQ-m or more, which was at a level that caused no practical problems.

(Example 2) This example is an example in which the shape of the recess formed in the joint surface of the molten metal and the ceramic shaft and the material of the metal member in Example 1 are changed.

FIG. 3 shows the shape of the book and the embodiment on a cross section taken along the line A--A in FIG.

The joint between the ceramic shaft 1 and the metal member 2 is formed by injecting a copper-zinc alloy of molten metal 9 into a recess 8 formed on the outer peripheral surface of the ceramic shaft 1 made of silicon nitride and a gap between the metal member 2 and the metal member 2. 2 is fitted with a heat-resistant metal ring 6 made of 5Cr40.
A metal shaft 4 made of heat-resistant metal 5Cr40 is welded to the shaft.

On the joint surface of the ceramic shaft 1, two recesses 8 are formed axially symmetrically and semicircularly with vertical surfaces in the radial direction and serve to prevent the shaft from slipping out and rotating. This recess 8 is formed by grinding a grindstone by only feeding it in the radial direction.

5Cr40 in this ceramic shaft 1! The metal ring 6 of the FJ was inserted, and the gap between the fitting parts was filled with molten metal 9 of a copper-zinc alloy heated to 900° C. and cooled. Next, the metal ring 6 was joined to the metal shaft 2 made of 5Cr401i by electron beam welding.

Also in this case, the ceramic 1 and the copper-zinc alloy of the molten gold 19 are not bonded to each other. Ceramic shaft 1
The processed shape of the four parts 8 and the molten metal 9 prevent the metal shaft 4 and the ceramic shaft 1 from being pulled out and prevent relative rotation between the metal shaft 4 and the ceramic shaft 1.

As in Example 1, the tensile strength (prevention of loss) and rotational torque were measured at 400°C. The tensile strength was 5 kgf or more, and the rotational torque was 4 kQ-m or more, which were at a level that caused no practical problems.

[Brief explanation of the drawing]

Fig. 1 is an explanatory longitudinal cross-sectional view of the joint of Example 1, Fig. 2 is a cross-sectional view taken along A-A of the joint of Example 1, and Fig. 3 is a cross-sectional view taken along A-A of Example 2. It is a front view. 1... Ceramic shaft 2... Metal member 3.8... Recessed portion 4... Shaft of metal member 5.9... Molten metal 6... Ring of metal member 7... Joint surface patent Applicant Toyota Motor Corporation

Claims (3)

[Claims] (1) A ceramic shaft having at least one recess on the outer circumferential surface of the axial joint end is inserted into a metal member having a shaft hole into which the ceramic shaft is fitted, and the outer circumferential surface of the axial joint end is A method for joining a ceramic shaft and a metal member, characterized in that the ceramic shaft and the metal member are joined by injecting and solidifying molten metal into the gap formed by the shaft hole and the inner peripheral surface of the shaft hole. (2) The method of joining a ceramic shaft and a metal member according to claim 1, wherein the recess is a spherical recess with an arcuate cross-section. (3) The method of joining a ceramic shaft and a metal member according to claim 1, wherein the recess is a groove having an arc-shaped cross section parallel to the axis of the axial joining end.