JPH063171B2 - Ceramic-Metal Friction Welding Body and Ceramic Casting Piston Composed of It - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a ceramics-metal friction welding body and a ceramic cast-in piston formed of the friction welding body, and is in the field of heat-resistant and wear-resistant parts such as engines and industrial machines. It has high utility value in.

[Prior Art] In recent years, for example, in pistons for internal combustion engines, in order to improve heat resistance and wear resistance, a piston in which ceramics and metal are integrally joined by a cast case is demanded in order to improve the heat resistance and wear resistance. Proposed and being implemented.

As for a ceramics-bonded piston in which a ceramics member and a metal member are integrally cast and joined, for example, JP-A-59-101566 and JP-A-62-200.
The one described in Japanese Patent No. 147 is known.

The ceramics-bonded piston described in Japanese Patent Laid-Open No. 59-101566 has a ceramic member and a metal member, a metallized layer adhered to the surface of the ceramic member, and a buffer metal member bonded to the metallized layer. It is the one that is integrally cast and joined through the via.

Further, the ceramic-bonded piston described in Japanese Utility Model Laid-Open No. 62-200147 has a groove formed on the outer circumference of the ceramic provided in the piston cavity, or the outer circumference is tapered so as to spread from the upper end surface side of the piston toward the bottom. It was formed to prevent the ceramics from falling off. It is also shown that a metallization treatment is applied to the outer circumference of the ceramic in order to achieve stronger bonding with the aluminum alloy.

[Problems to be Solved by the Invention] However, the ceramics-bonded piston described in JP-A-59-101566 is intended to bond the piston body and the ceramics with the bonding force of the metallized layer. In order to withstand the inertial force of the piston and the stress caused by thermal deformation, a metallized layer is formed on a wide area of the surface where the piston body and ceramics contact. However, uniform metallization over a wide range is not preferable because it is technically difficult and the manufacturing cost becomes high.
In addition, since the metallized layer alone bears the stress due to inertial force, thermal deformation, etc., it lacks reliability in terms of strength, and the joint surface peels off during piston operation, and combustion gas will flow in from the peeled portion. There are inconveniences that the fuel efficiency is lowered and the fuel efficiency is deteriorated, and the piston base material is damaged and carbon is accumulated.

On the other hand, in the ceramics-bonded piston described in Japanese Utility Model Laid-Open No. 62-200147, as described above, the groove is formed on the outer circumference of the ceramic, or the outer circumference is formed in a tapered shape to prevent the ceramic from falling off. However, no measures have been taken from the viewpoint of sealing, which prevents the combustion gas from flowing in from the joint surface. This is apparent from the fact that in the embodiment of FIG. 5 of this publication, no treatment is applied to the piston outer peripheral side of the joint surface between the piston top surface and the ceramics.

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

That is, according to the present invention, there is provided a friction pressure welding body constituted by interposing an aluminum member between a ceramic member and a metal member, wherein a notch portion is provided on an outer peripheral portion of the ceramic member joining surface. There is provided a ceramics-metal friction welding body characterized by joining the metal member and the aluminum member to the notch portion by friction welding.

Further, according to the present invention, in a ceramic cast-in piston which is formed by casting a top plate made of a ceramic member with an aluminum alloy forming a piston body,
There is provided a ceramic cast-in piston which is characterized in that a notch is provided in an outer peripheral portion of a surface of the top plate which is in contact with a piston body, and a metal annular member and an aluminum annular member are frictionally pressure-welded to the notch. It

The friction welding body of the present invention can be said to be particularly suitable when a metal member which is difficult to be joined to ceramics by direct friction welding is used.

According to the present invention, since the aluminum member is interposed between the ceramic member and the metal member that is difficult to be directly bonded to the ceramic, a ceramic-metal friction welding body that is more firmly bonded is provided. can do.

INDUSTRIAL APPLICABILITY The ceramic-metal friction welding body according to the present invention can be applied to a ceramic cast-gear piston as described above, and an engine valve including a metal 20 and a ceramic 21 [see FIGS. 8 (a) and 8 (b)]. Also, the ceramics 21 is friction-welded to the sliding portions of the rocker arm 24, the push rod 25, and the tappet 26 for transmitting the power for operating the engine valve [see FIG. 8 (c)], and the industrial machinery field. It can be used for the corrosion-resistant and heat-resistant equipment, such as ceramic spindles and ceramic rotors of acid-resistant pumps.

Friction welding here means that the materials to be joined are brought into contact with each other, the joining surfaces are moved relative to each other under a constant pressure, and the friction heat generated in the surfaces raises the joining surfaces to a high temperature. It is a method of plastically flowing a metal material to join them by pressure, and although there are restrictions on the shape and size of the joined parts, there are features that other joining methods do not have, especially effective for joining dissimilar materials. It is a simple joining method.

In the present invention, as the material of the ceramic member,
Ceramics excellent in heat resistance, thermal shock resistance, heat insulation, and weight reduction are preferable, and it is preferable that they are 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 the ceramic member. For example, Ag, C
u, Ti, Nb, Mo, W, Ni, Fe, Inconel,
Incoloy or the like can be used, but it is of course possible to use it even if it can be directly friction-welded with ceramics such as Al. In this case, a friction-welded body can be obtained in which the joining force is more reliable. it can.

As for the shape of the cutout portion provided on the outer peripheral portion of the ceramic member, the circumferential thickness is preferably 20% or less of the diameter of the ceramic member, and more preferably 10% or less,
Further, it is slightly smaller than the inner diameter of the metal annular member, for example, 1
It is preferable to make a notch smaller than%. Also, the distance t (see FIG. 1) on the side surface of the notch portion of the ceramic member needs to be determined in consideration of the stress required for the joint surface, but in the case of a component such as a ceramic piston which is affected by heat, It is preferable that t = 3 to 10 mm.

When the metal member is used as the annular member of the ceramic member, the thickness in the circumferential direction (1 / the difference between the inner diameter and the outer diameter) is used.
Although 2) is not particularly limited, 20% or less of the diameter of the ceramic member is preferable, and 10% or less is more preferable. This is because the temperature distribution generated on the friction welding surface can be made small, so that the generation of thermal stress also becomes small.

The surface roughness of the ceramic member is 0.05 to 1.0.
μmRa is preferable, and if the flatness of the press contact surface can be controlled, it can be used as it is as the baked surface.

Next, for convenience of description, a reference example that is not an example will be described. This will make the embodiments of the present invention described later clearer.

FIG. 1 is a schematic sectional view showing an example of a ceramic-metal friction welding body.

The ceramic member 1 made of silicon nitride or the like is provided with a notch 2 on the outer peripheral surface of the surface facing the metal member 3 such as Ti, and the metallic annular member 3 is joined to the notch 2 by friction welding. . In the above joining, the ceramic member 1
By providing the gap A between the metal annular member 3 and the metal annular member 3, the metal annular member 3 softened by frictional heat can form the gap A.
The plastic flow occurs and the projection 4 of the ceramic member 1 is constrained by the shrink fitting / press-fitting action. 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 converted into a volume of the softening amount of the metal annular member 3 at the time of friction welding, and is ⅓ of the volume amount. The amount of the convex portion 4 of the ceramic member 1
It is preferable that the value of the gap A is estimated by inferring the amount of metal that flows into the gap A of the metal annular member 3 and, for example, if the gap A is 0.2 to 1 mm, particularly good results are obtained.

FIG. 2 is a schematic cross-sectional view showing another example of the ceramic-metal friction welding body. The convex portion 4 of the ceramic member 1 shown in FIG. Is a constriction with a curvature R = 1.5 inward. In this case, since the metal softened by friction welding plastically flows into the constricted portion, a higher-performance detachment prevention effect than that in the case of FIG. 1 can be expected.

In the above ceramic-metal friction welding body,
When friction welding was performed with ceramic Ti metal processed to r ₁ : 20 mmφ, r ₂ : 14 mmφ, t: 5 mm, and a tensile test (room temperature) of the friction welding body was performed, in the case of FIG. 1, the load was 1700 kg. In the case of FIG. 2, the joint part came off under a load of 2800 kg.

From the above, as compared with the example shown in FIG. 9, in the ceramic-metal joining structure in which the ceramic member does not have the notch, joining with a dissimilar metal other than aluminum was not possible. By making the member made into a notch structure, friction welding of a different metal other than aluminum and ceramics becomes possible.

In addition, it is preferable to anneal the friction-welded body in a use temperature range.

Further, when friction welding is performed in an inert gas or vacuum, oxidation is not promoted, and thus brittle fracture of the material can be reduced, which is preferable.

Next, a description will be given of a reference example in the case where the friction welding body is applied to a cast ceramics piston for an internal combustion engine.

Reference Example 1 As shown in FIG. 3 (a), a notch 6 having a width of 3 mm and an additional 3 mm is provided on the outer peripheral portion of the surface corresponding to the piston body 5 (FIG. 3 (d)). A silicon nitride crown 7 having an outer diameter of 90 mmφ was produced.

Next, as shown in FIG. 3 (b), a titanium annular ring 8 having an inner diameter of 80 mmφ, an outer diameter of 90 mmφ and a length of 50 mm is formed, and then the crown 7 is fixed to attach the titanium annular ring 8 to the crown. 7 was rotated at 800 rpm, the pressure was gradually increased, and the crown 7 was pressed at a pressure of 3 kg / mm ² at maximum and frictionally welded to obtain a ceramic-metal bonded body.

Further, the outer circumference of the titanium ring 8 is processed to form a titanium ring member 9 having a piston axial length of 4 mm as shown in FIG. 3 (c).
Then, after subjecting the B side of the annular member 9 to an alfine treatment (Almelt treatment may be used), the silicon nitride crown 7 provided with the annular member 9 is placed in a sand mold and the temperature is about 700 ° C. A cast aluminum body was obtained by pouring aluminum alloy hot water into the mold. This was annealed at a temperature near the piston use temperature, and finish processing such as outer peripheral processing, ring groove processing, piston pin hole processing, etc. was performed to produce a ceramics cast gurney piston sealed by a titanium annular member. (See FIG. 3 (d)) In this reference example, the material of the metal member used for friction welding with silicon nitride is titanium, but the same performance and effect can be obtained even with cast iron having a low material cost. It is possible.

Reference Example 2 The same procedure as in Reference Example 1 was carried out except that the notched portion 6 of the silicon nitride crown 7 was formed into a shape with a slope of 70 ° as shown in FIG. 4 (a). (B) A ceramic cast-in piston that was sealed by the 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 10 between the titanium annular member 9 of the piston and the aluminum alloy piston body 5.

In the present reference example, the notch 6 of the silicon nitride crown 7 is provided with a gradient that is connected to the radius, and titanium softened by friction welding flows into this radius portion, so that the removal prevention effect is enhanced. Further, as described above, by joining the joining surface 10 by laser beam welding or electron beam welding, the joining between the titanium annular member 9 and the piston body 5 was strengthened, and a high-performance ceramic cast-in piston was manufactured. Further, the surface of the titanium annular member 9 that contacts the aluminum alloy may be subjected to alfin and almelt treatment to bond it to the aluminum alloy hot water.

Reference Example 3 The same method as in Reference Example 1 except that the surface is a fired surface
A silicon nitride crown 7 having a cutout portion as shown in FIG.

Further, as shown in FIG. 5 (b), in order to relieve the stress due to the joining between the aluminum alloy piston body 5 and the silicon nitride crown 7, a deep hole 1 is formed at the center of the piston body 5.
1 was opened, and the central deep hole 11 of the aluminum alloy piston main body 5 was machined 7 to 10 mm deeper than the dimension of the convex portion G of the silicon nitride crown 7 so as not to be joined to the crown bottom surface C.

Next, the titanium annular member 9 was frictionally pressure-welded to the piston body 5. After that, the protrusion length of the titanium annular member 9 of the aluminum alloy piston body 5 is processed to be the same as the cutout dimension F of the outer peripheral portion of the silicon nitride crown 7, and the aluminum alloy piston that is in contact with the side surface of the silicon nitride crown 7 is processed. The contact surface of the main body 5 was processed so as to have a gap E of 0.2 to 1 mm. Then, as shown in FIG. 5 (c), the crown 7
And the piston body 5 integrated with the titanium annular member 9 were friction-welded. In this case, the C portion of the crown 7 is retained by the shrink fitting press-fitting effect of the aluminum alloy of the piston body 5, the silicon nitride and the aluminum alloy are frictionally welded to each other at the H portion, and the titanium annular member 9 is connected to the crown 7 with the crown 7. Of the crown 7 is softened by the frictional heat of the above and bites into the notch 6 of the crown 7, and the sealing property of the C portion is improved by the shrink fitting press-fitting effect.

Then, this was machined to produce a ceramics piston sealed by a titanium annular member 9 as shown in FIG. 5 (c).

[Examples] Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1 Similar to Reference Example 1 except that the titanium annular member 9 was replaced with the annular member 13 including the aluminum annular member 12 and the titanium annular member 9, and the aluminum annular member 12 was positioned on the crown 7 side. By the method described above, a ceramics cast stuff piston shown in FIG. 6 was obtained. In this piston, the aluminum annular member 12 is present between the ceramic crown 7 and the titanium annular member 9, but since the ceramic and aluminum are highly bondable, a ceramic piston having better bondability can be manufactured. It was As the material of the aluminum annular member 12, a material having high aluminum purity is preferable, and in the present embodiment, Al purity is 9
9.5% A1050 was used. Although titanium is used as the annular member 9 in this embodiment, it may be made of cast iron, and niresist cast iron used as a piston ring carrier material is particularly preferable.

(Example 2) As shown in FIG. 7, an annular member 13 having a shape in which the aluminum annular member 12 is located on the inner peripheral side of the titanium annular member 9.
A ceramic piston similar to that in Example 1 was manufactured except that Compared to the first embodiment, this piston is
Aluminum is not exposed where it is exposed to the fuel gas of the engine, and it is covered with titanium, so corrosion resistance is good, and because aluminum is interposed between titanium and ceramics, the jointability is also high and a high-performance ceramic piston is used. It was possible to make.

[Effects of the Invention] As is apparent from the above, according to the present invention, the following effects can be obtained.

The friction pressure welding body according to claim 1, wherein when the ceramic member is joined to the metal member and the aluminum member, a notch portion is provided in the ceramic member to perform friction welding.
The side surface of the joined body is provided with the characteristics of shrink fitting and press fitting. The restraining force due to the shrink fitting / press-fitting action is determined by the coefficient of thermal expansion when the metal softened by frictional heat is hardened. Therefore, a strong binding force is obtained and a high binding force is obtained. Further, since the aluminum member is interposed between the ceramic member and the metal member, it is possible to provide a more firmly joined friction welding body.

Therefore, it is not necessary to improve the processing accuracy of the joining parts as compared with the conventional shrink fitting / press-fitting technology, and the complicated work is not required as compared with the metallized joining, so that the cost can be reduced, and mass production is possible. Suitable for conversion.

According to the cast ceramic piston according to the second aspect of the present invention, a highly reliable bond can be obtained because of the shrink fitting / press-fitting action on the side surface of the joint and the high bondability between the ceramic and aluminum. In addition, since it is not necessary to improve the processing accuracy of the joining component and complicated work such as metallization is not required, the cost can be reduced, which is suitable for mass production.

[Brief description of drawings]

1 and 2 are schematic sectional views showing a reference example of a ceramic-metal friction welding body, and FIGS. 3 (a) (b) (c).
(d), FIG. 4 (a) (b) and FIG. 5 (a) (b) (c) are schematic cross-sectional views showing a reference example when a friction welding body is applied to a ceramic piston, FIG. 6 and FIG. 7 is a schematic sectional view showing an embodiment when the present invention is applied to a ceramic piston,
FIG. 8 is a schematic view of an application example of the present invention, (a) and (b) are engine valves, (c) is an explanatory view showing a rocker arm, and FIG. 9 is an explanation showing a conventional friction welding structure. It is a figure. DESCRIPTION OF SYMBOLS 1 ... Ceramic member, 2 ... Notch part, 3 ... Annular member, 4 ... Convex part, 5 ... Piston body, 6 ... Notch part, 7 ...
Crown made of silicon nitride, 9 ... Titanium ring member, 12 ... Aluminum ring member, 13 ... Ring member, 27 ... Metal member,
28 ... Friction pressure contact surface.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display area F02F 3/00 302 A 8503-3G

Claims (2)

[Claims] Claims: 1. A friction pressure welding body constructed by interposing an aluminum member between a ceramic member and a metal member, wherein a cutout portion is provided on the outer peripheral portion of the joining surface of the ceramic member. A ceramic-metal friction welding body, characterized in that the metal member and the aluminum member are joined to the notch by friction welding. 2. A ceramic cast-rough piston formed by casting a top plate made of a ceramic member with an aluminum alloy forming a piston body, wherein a notch is provided in an outer peripheral portion of a surface of the top plate in contact with the piston body. A ceramic cast-in piston which is characterized in that a metal annular member and an aluminum annular member are friction-welded to the notch.