JPH02115555A - Friction welded body of ceramics-metal and ceramics-inserted piston made thereof - Google Patents

Abstract

PURPOSE:To heighten the bonding power and aim at lowering the cost by providing a cutout part at the peripheral part of the face to be bonded of a ceramics- made member and bonding a metal made member to this cutout part by friction welding. CONSTITUTION:A piston for an internal combustion engine is integrally bonded by inserting a ceramics-made member 1 and a metal-made member 3. A cutout part 2 is provided at the peripheral part of the face of the ceramics-made member 1 facing the metal-made member 3. The metal-made annular member 3 is bonded to this cutout part 2 by friction welding. The metal made annular member 3 softened by frictional heat plastically flows into a gap A and restrains the projecting part 4 of the ceramics-made member 1 by the action of shrinkage fit and press fitting. The bonding power is thus heightened and the decrease in the cost is promoted.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a friction welded body made of a ceramic member and a metal member, and a ceramic cast piston made of the same, and is used as a heat-resistant and wear-resistant part of an engine, etc. It has high utility value in the fields of industrial machinery and other fields.

[Prior Art] In recent years, pistons for internal combustion engines, for example, have been made by integrally joining ceramics and metals by casting, in order to improve heat resistance and wear resistance, along with the demand for lighter engine bodies. It has been proposed and is being put into practical use.

Ceramic-bonded pistons in which a ceramic member and a metal member are integrally joined by casting are disclosed in, for example, Japanese Patent Application Laid-open No. 59-101566 and Utility Model Application No. 62-200.
The one described in Publication No. 147 is known.

The ceramic bonded piston described in JP-A-59-101566 includes a ceramic member and a metal member, a metallized layer adhered to the surface of the ceramic member, and a buffer metal body bonded to the metallized layer. This is a one-piece cast-instrumented joint.

Furthermore, the ceramic bonded piston described in Japanese Utility Model Application Publication No. 62-200147 has a groove formed on the outer periphery of the ceramic provided in the piston cavity, or the outer periphery is tapered so as to widen from the top end surface of the piston toward the bottom. This is an attempt to prevent the ceramic from falling off. It has also been shown that metallization treatment is applied to the outer periphery of the ceramic in order to achieve stronger bonding with the aluminum alloy.

[Problems to be Solved by the Invention] However, the ceramic bonded piston described in JP-A-59-101566 is intended to bond the piston body and ceramics using the bonding force of the metallized layer. In order to withstand stress caused by inertia of the piston, thermal deformation, etc., a metallized layer is formed over a wide area of the contact surface between the piston body and the ceramic. However, it is not preferable to uniformly metalize a wide area because it is technically difficult and increases the manufacturing cost. In addition, since the metallized layer alone receives stress due to inertial force, thermal deformation, etc., it lacks reliability in terms of strength, and when the piston is operated, the joint surface will peel off and combustion gas will flow in from the peeled part. In addition to lowering the combustion efficiency of the engine and worsening fuel efficiency, there are disadvantages such as damage to the piston base material and accumulation of carbon.

On the other hand, the ceramic bonded piston described in Japanese Utility Model Application No. 62-200147 prevents the ceramic from falling off by forming a groove on the outer periphery of the ceramic or by forming the outer periphery in a tapered shape. However, no measures have been taken from the viewpoint of sealing to prevent combustion gas from flowing in from the joint surface. This means that in the example shown in FIG. 5 of this publication, This is clear from the fact that no treatment has been applied to the outer peripheral side of the piston, which is the joint surface between the top surface of the piston and the ceramic.

[Means for Solving the Problems] Therefore, the inventors of the present invention have conducted various studies in view of the above-mentioned conventional problems, and as a result, have arrived at the present invention.

That is, according to one aspect of the present invention, there is provided a friction welded body consisting of a ceramic member and a metal member, wherein a notch is provided on the outer periphery of the joining surface of the ceramic member, and the metal member is placed in the notch. A ceramic-metal friction welded body characterized by being joined by friction welding is provided.

According to one aspect of the present invention, in a ceramic cast piston in which the top plate made of a ceramic member is cast in an aluminum alloy forming the piston body,
A ceramic cast piston is provided, characterized in that a notch is provided on the outer periphery of the surface of the top plate that contacts the piston body, and a metal annular member is frictionally welded to the notch.

The friction welded body of the present invention is particularly suitable when using a metal member that is difficult to join with ceramics by direct friction welding.

In addition, if aluminum is interposed between a ceramic member and a metal member that is difficult to join directly to the ceramic, the ceramic member will be more strongly joined.
A metal friction welding body can be provided.

As described above, the ceramic-metal friction welded body according to the present invention can be applied to a ceramic-cast piston, as well as an engine valve made of a metal 20 and a ceramic 21 (see FIGS. 8(a) and 8(b)). In addition, ceramics 21 are friction-welded to the sliding parts of the rocker arm 24, bushing rod 25, and tappet 26 that transmit the power to titi@ the engine valve [Fig. 8 (
c)] and corrosion-resistant/heat-resistant equipment in the industrial machinery field, such as ceramic spindles and ceramic rotors for acid-resistant pumps.

Here, friction welding refers to bringing the materials to be joined into contact with each other, moving the joining surfaces relative to each other under a constant pressure, and raising the temperature of the joining surfaces with the frictional heat generated within the plane. It uses pressure to plastically flow metal materials to join them together, and although there are restrictions such as the shape and size of the parts to be joined, it has features that other joining methods do not have, and is particularly effective for joining dissimilar materials. This is a unique joining method.

In the present invention, the material of the ceramic member is as follows:
Ceramics with excellent heat resistance, thermal shock resistance, heat insulation properties, and weight reduction are preferred, and are preferably composed of one selected from the group consisting of silicon nitride, silicon carbide, sialon, zirconia, mullite, and alumina.

In the present invention, the metal member used for friction welding with the ceramic member is effective if it is a metal that cannot be directly friction welded with ceramics, such as Ag, C
U, Ti, Nb, Mo, WNi, Fe, Inconel, Incoloy, etc. can be used, but it is also possible to use other materials that can be directly friction welded with ceramics such as AJ1, and in this case, the bonding will be better. A friction welding body with reliable force can be obtained.

In addition, as for the shape of the notch provided on the outer peripheral part of the ceramic member, the thickness in the circumferential direction is preferably 20% or less of the diameter of the ceramic member, more preferably 10% or less,
Furthermore, it is slightly smaller than the inner diameter of the metal annular member, for example, 1
It is preferable to make the notch smaller than %.Also, it is necessary to determine the distance on the side surface of the notch part of the ceramic member (see Figure 1), taking into account the stress required on the joint surface, but it is necessary to For parts that are affected by heat, it is preferable that t=3 to 11011.

In addition, when a metal member is used as an annular member of a ceramic member, its circumferential thickness (l/2 of the difference between the inner and outer diameters)
) is not particularly limited, but 2 of the diameter of the ceramic member
It is preferably 0% or less, more preferably 10% or less. This can reduce the temperature distribution that occurs on the friction welding surface, so
This is because the occurrence of thermal stress is also reduced.

Note that the surface roughness of the ceramic member is 0.05 to 1. O
ILmRa is preferable, and the fired surface can be used as is if the flatness of the pressure contact surface can be controlled.

[Examples] Hereinafter, the present invention will be described in more detail based on illustrated examples, but the present invention is not limited to these examples.

FIG. 1 is a schematic sectional view showing an embodiment of the ceramic-metal friction welding body of the present invention.

A ceramic member 1 made of silicon nitride or the like.

A notch 2 is provided on the outer periphery of the surface facing the metal member 3 such as Ti, and the metal annular member 3 is joined to the notch 2 by friction welding. In the above joining, by providing a gap A between the ceramic member 1 and the metal annular member 3, the metal annular member 3, which has been softened by frictional heat, plastically flows into the gap A, and is burnt out and enlarged due to the The convex portion 4 of the ceramic member l is restrained. At this time, the value of the gap A between the convex portion 4 of the ceramic member 1 and the metal annular member 3 is calculated by converting the softening amount of the metal annular member 3 during friction welding into volume, and calculating the value by 173 of the volume. If the amount is estimated to be the amount that flows into the inside of the gap A between the convex part 4 of the ceramic member 1 and the metal annular member 3, and the value of the gap A is set as 1, for example, the gap A is preferably 0.2 to 11! Particularly good results are obtained when Il is used.

FIG. 2 is a schematic sectional view showing another embodiment of the ceramic-metal friction welded body of the present invention. The root portion of 4 is constricted inward with a curvature R=1.5. In this case, since the metal softened by friction welding plastically flows into the constricted portion, it is expected that a higher performance in preventing removal than in the case of FIG. 1 can be expected.

In the above ceramic-metal friction welded body, r,
: 20mmφ, r*: 14mmφ, t: Friction welded with Ti metal using ceramics processed to 5mm.
When a tensile test (room temperature) of the friction welded body was performed, the first
In the case shown in the figure, the joint came off at a load of 1,700 kg, and in the case of FIG. 2, at a load of 2,300 kg.

From the above, compared to the conventional example shown in FIG.
With metal joining structures, it has been impossible to join dissimilar metals other than aluminum, but by creating a ceramic member with a notch structure as in the present invention, friction welding of dissimilar metals other than aluminum and ceramics is possible. becomes.

Note that it is preferable that the friction welded body is annealed in the operating temperature range.

Furthermore, it is preferable to perform friction welding in an inert gas or vacuum environment because oxidation is not promoted and the brittleness and destruction of the material can be reduced.

Next, a specific example will be described in which the friction welding body of the present invention is applied to a ceramic cast piston for an internal combustion engine.

(Example 1) As shown in FIG. 3(a), the piston body 5 (FIG. 3(a)
d) Width 3mm and depth 3111 on the outer periphery of the surface opposite to
A crown 7 made of silicon nitride and having an outer diameter of 90 mm and a notch 6 was fabricated.

Next, as shown in FIG. 3(b), a titanium ring 8 with an inner diameter of 80mm, an outer diameter of 90mm, and a length of 50+*m is made, and the crown 7 is fixed thereon. The ring 8 is rotated at 800 rpm relative to the crown 7, and the pressure is gradually increased to press the ring 8 against the crown 7 at a maximum pressure of 3 kg/g+n'' for friction welding, thereby forming a ceramic-metal composite. Obtained.

Furthermore, the outer periphery of the titanium ring 8 was processed to create a titanium annular member 9 having a piston axial length of 4+sm as shown in FIG. 3(C), and the B side of the annular member 9 was subjected to Alfin treatment After that (alumel treatment may be used), the silicon nitride crown 7 provided with the annular member 9 is placed in a sand mold, and aluminum alloy hot water at about 700°C is poured into the mold to obtain a ceramic cast body. Ta. This was annealed at a temperature close to the piston operating temperature, and finishing processes such as outer periphery machining, ring groove machining, and piston pin hole machining were performed to produce a ceramic cast piston sealed with a titanium annular member. (See Figure 3(d)) In this example, the material of the metal member used for friction welding with silicon nitride was made of titanium, but cast iron, which has a lower material cost, can also be used to obtain similar performance and effects. Is possible.

(Example 2) The process was carried out under the same conditions as in Example 1 except that the notch 6 of the silicon nitride crown 7 was shaped with a slope 706 as shown in FIG. 4(a). b) A ceramic six cast piston sealed by a titanium annular member 9 as shown in the figure was produced. Next, laser beam welding or electron beam welding was performed on the joint surface lO between the titanium annular member 9 and the aluminum alloy piston body 5 of the piston.

In this embodiment, the notch 6 of the silicon nitride crown 7 is sloped to connect with a radius, and titanium softened by friction welding flows into this radius, thereby increasing the effect of preventing removal. Further, as described above, by laser beam welding or electron beam welding the joint surface 10, the joint between the titanium annular member 9 and the piston body 5 is strengthened, and a high-performance ceramic cast piston can be manufactured. Alternatively, the surface of the titanium annular member 9 in contact with the aluminum alloy may be subjected to Alfin and Alumel treatment to be bonded to the aluminum alloy hot water.

(Example 3) In the same manner as in Example 1 except that the surface or the firing surface was used, the fifth
A silicon nitride crown 7 provided with a notch as shown in Figure (a) was manufactured.

In addition, as shown in FIG. 5(b), in order to relieve the stress caused by joining the aluminum alloy piston body 5 and the silicon nitride crown 7, a deep hole is formed in the center of the piston body 5.
The central deep hole 11 of the aluminum alloy piston body 5 was machined to be 7 to 10 mm deeper than the convex portion G of the silicon nitride crown 7 so as not to connect with the bottom surface C of the crown.

Next, a titanium annular member 9 was frictionally welded to the piston body 5. Thereafter, the protruding length of the titanium annular member 9 of the aluminum alloy piston body 5 is processed to be the same as the outer peripheral notch dimension F of the silicon nitride crown 7, and the aluminum alloy piston is in contact with the side surface of the silicon nitride crown 7. The contact surface of the main body 5 was machined to have a gap E of 0.2 to [l].Then, as shown in FIG. 5(c), the crown 7 and the titanium annular member 9 were integrated. The piston body 5 was frictionally welded to the piston body 5. In this case, the 0 part of the crown 7 is prevented from being pulled out by the burn-off press-fitting effect of the aluminum alloy of the piston body 5, and the silicon nitride and aluminum alloy are friction welded at the H part, and the titanium annular member 9 is attached to the crown 7. It softens due to the frictional heat and bites into the notch 6 of the crown 7, and the sealing performance of the C portion is improved by the burn-off press-fitting effect.

This was then machined to produce a ceramic piston sealed by a titanium annular member 9 as shown in FIG. 5(c).

(Example 4) Same as Example 1 except that the titanium annular member 9 was replaced with an annular member 13 consisting of an aluminum annular member 12 and a titanium annular member 9, and the aluminum annular member 12 was positioned on the crown 7 side. By the method described above, a ceramic cast piston shown in FIG. 6 was obtained. This piston has an aluminum annular member 12 between the ceramic crown 7 and the titanium annular member 9, but since the bondability between ceramic and aluminum is high, a ceramic piston with better bondability can be manufactured. Ta. Note that the material of the aluminum annular member 12 is preferably a material with high aluminum purity, and in this embodiment, AfL purity is 9.
9.5% A1050 was used. Although the annular member 9 is made of titanium in this embodiment, it may also be made of cast iron, and Niresist cast iron used as a piston ring carrier material is particularly preferred.

(Example 5) As shown in FIG. 7, an annular member 13 having a shape in which an aluminum annular member 12 is positioned on the inner peripheral side of a titanium annular member 9.
A ceramic piston similar to that in Example 4 was produced except that . This piston, compared to Example 4,
Aluminum is not exposed in the parts exposed to engine combustion gas and is covered with titanium, so it has good corrosion resistance, and since aluminum is interposed between titanium and ceramics, it has high bonding properties, making it possible to use high-performance ceramic pistons. I was able to create one.

[Effects of the Invention] As is clear from the above, the present invention provides the following effects.

In the friction welded body according to claim 1, in joining a ceramic member and a metal member, the notch portion is provided in the ceramic member and the side surface of the joined body has properties of burning and press-fitting by friction welding. It is something that The restraining force due to the firing and press-fitting action is determined by the coefficient of thermal expansion of the metal that has been softened by frictional heat and hardened. Therefore, it becomes a strong binding force and a high bonding force can be obtained.

Therefore, compared to conventional burning and press-fitting techniques, there is no need to increase the processing precision of parts to be joined, and compared to metallized joining, there is no need for complicated work, making it possible to reduce costs and mass production. suitable for

According to the friction welded body according to the second aspect of the present invention, it is possible to provide a strong friction welded body even with metal members that are difficult to join with ceramics by direct friction welding.

According to the friction welded body according to the third aspect, it is possible to provide a friction welded body that is more firmly joined.

According to the ceramic cast piston according to the fourth aspect, a highly reliable connection can be obtained due to the firing and press-fitting action on the side surface of the joint portion. In addition, there is no need to increase the processing accuracy of the joining parts, and there is no need for complicated work such as metallization, so costs can be reduced and it is suitable for mass production.

[Brief explanation of drawings]

1 and 2 are schematic cross-sectional views showing examples of the ceramic-metal friction welding body of the present invention, and FIG. 3 (a
) (b) (c) (d) and Figure 4 (a) (b)
5(a) and 5(b) are schematic sectional views showing an example in which the friction welding body of the present invention is applied to a ceramic piston.
(C), FIGS. 6 and 7 are schematic sectional views showing other embodiments in which the present invention is applied to a ceramic piston,
Fig. 8 is a schematic diagram of an application example of the present invention, (a) and (b) are an explanatory diagram showing an engine valve, (C) is an explanatory diagram showing a rocker arm, and Fig. 9 is an explanatory diagram showing a conventional friction welding structure. It is.

Claims (4)

[Claims] (1) A friction welded body consisting of a ceramic member and a metal member, wherein a notch is provided on the outer periphery of the joining surface of the ceramic member, and the metal member is joined to the notch by friction welding. A ceramic-metal friction welding body characterized by: (2) The ceramic-metal friction welded body according to claim 1, wherein the metal member is a member that is difficult to join with the ceramic by direct friction welding. (3) The ceramic-metal friction welded body according to claim 1 or 2, wherein aluminum is interposed between the ceramic member and the metal member. (4) In a ceramic cast piston, which is made by casting a top plate made of a ceramic member with an aluminum alloy that forms the piston body, a notch is provided on the outer periphery of the surface of the top plate that comes into contact with the piston body; A ceramic cast piston characterized by being made by friction welding a metal annular member.