JPH02308953A - Machine element made of fiber-reinforced metal - Google Patents

Abstract

PURPOSE:To maintain the abrasion resistance of a machine element made of a fiber-reinforced metal by etching the surface of the machine element made of a fiber-reinforced metal, exposing part of reinforcing fibers, and forming a plated layer on its surface. CONSTITUTION:Reinforcing fibers 2 are combined with a light metal base material 1, and a circular reinforcing body 5 to form the top land 4 of a piston 3 is constituted. The top ring groove 6 of the piston 3 is etched after melt- forging, and reinforcing fibers 2 are exposed on the surface of the top ring groove 6. Electroless hard plating is applied to the top ring groove 6. A hard plated layer 8 using reinforcing fibers 2 as a base material is integrally formed on the surface of the top ring groove 6. The peeling strength of the hard plated layer is improved, and the abrasion resistance of the piston 3 can be maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a mechanical element made of fiber-reinforced metal, which is a composite of a metal such as aluminum having a large coefficient of thermal expansion and reinforcing fibers such as ceramic.

[Prior Art] In recent years, light alloys such as aluminum have been adopted as metal materials for forming machine elements in an effort to reduce the weight of machine elements.

By the way, when aluminum is used for mechanical elements that require wear resistance, such as the piston of an internal combustion engine, the degree of wear is high, so countermeasures such as applying surface treatment to the surface of the aluminum are required.

As a countermeasure for pistons, there is a method in which links made of Ni-Resist cast iron, which have high wear resistance, are cast into the piston, and screw grooves are formed in the rings.Ni, Ni-3iC (or S ,j s
Attempts have been made to form a hard plating layer of N4, etc.).

[Problems to be Solved by the Invention] However, when using light metals such as aluminum that have a high coefficient of thermal expansion, there is a problem that peeling occurs at the boundary between the light metal and the above-mentioned ring or a hard plating layer peels off from the light metal due to thermal cycling. There is.

As a related technology, we have developed a ``fiber-reinforced metal composite material member and its manufacturing method'' (Special Features), which prepares various reinforcing fibers with different lengths relative to the diameter of the reinforcing fibers and adjusts the internal and external strength and abrasion resistance of mechanical elements. Although there is a proposal (Japanese Patent Publication No. 5L74247), it does not attempt to improve the peel strength against thermal cycles.

An object of the present invention is to form a hard plating layer with high peel strength on the surface of fiber-reinforced metal to compensate for the wear resistance of mechanical elements made of fiber-reinforced metal.

[Means for Solving the Problems] In order to achieve the above object, the present invention etches the surface of a fiber-reinforced metal machine element formed by combining metal and reinforcing fibers to remove some of the reinforcing fibers. A mechanical element made of fiber-reinforced metal is constructed by exposing the metal and forming a plating layer on its surface.

[Function] Since the reinforcing fibers prevent the thermal expansion of the metal and the fiber-reinforced metal mechanical element, the fiber-reinforced metal mechanical element can maintain a certain level of performance. Then, by etching an exposed surface of reinforcing fibers on the surface of this fiber-reinforced metal mechanical element, and applying hard plating to this exposed surface,
The exposed portion of the reinforcing fibers serves as a base material for the hard plating layer and prevents the hard plating layer from peeling off due to thermal expansion.

Therefore, it is possible to provide a fiber-reinforced metal mechanical element in which the peel strength of the hard plating layer itself is improved while suppressing thermal expansion in the fiber-reinforced metal mechanical element itself.

[Example 1] A piston for an internal combustion engine equipped with a fiber-reinforced metal mechanical element as a reinforcing member will be described below with reference to the accompanying drawings.

The part of the internal combustion engine that undergoes the largest heat cycle is the top side of the piston, and the part that generates the screw slap sound is the piston top ring that is integrally fitted to the screw brand of the screw. Therefore, in the example, the one-height brand of screws is reinforced along the circumferential direction with a fiber-reinforced metal reinforcement to cope with thermal expansion, and this reinforcement is used for wear resistance. A hard plating layer is formed on the surface of the screw 1 hent spring groove to be formed.

Specifically, as shown in Figure 1, aluminum (JIS
-A, C8A), etc., and a composite material (for example, SiC).

An annular reinforcing body 5 for forming the top land 4 of the screws 1 to 3 shown in FIG. 2 is constructed by compositing reinforcing fibers 2 of ceramic such as Si3N4.

That is, in the second embodiment, the volume ratio of the composite material 2 to the light metal base material 1 is about 15% Vf, and the reinforcement body 5 is made of fiber reinforced metal (FRM). The reinforcement body 5 is formed, for example, by a molten metal forging method in which the light metal base material 1 is solidified while being pressurized at a constant pressure (500 to looObg/aa),
A top ring groove 6 is formed on the outer circumferential surface of the reinforcing body 5 at the same time as or after the reinforcing body 5 is molded.

Such a reinforcement body 5 is installed in a molten metal mold (not shown) that forms the outer shell of the piston 3, and is integrated with the piston 3 by solidification of the light metal molten metal poured into the molten metal forging mold.

Now, in this example, one of the pistons 3 after molten metal forging
- The tubing groove 6 is etched (as shown in FIG. 3).
The reinforcing fibers 2 are etched with a solution 7 (for example, a 10% NaOH aqueous solution) to expose the reinforcing fibers 2 on the surface of the top ring groove 6, as shown in FIG.

Perform electroless hard plating treatment such as Ni-8iC (or 5i3N4). In other words, on the surface of the top ring groove 6,
A hard plating layer 8 using the reinforced edge [2 as a base material] is integrally formed.

As described above, the reinforcing body 5 is formed of m-fiber-reinforced metal to suppress the thermal expansion of the piston 3, and the hard mesh layer 8 is formed on the surface of the twining grooves 1 to 6 using the reinforcing fiber 2 as a base material. Then, the reinforcing fibers 2 prevent the thermal expansion of the light metal base material 1 and minimize the thermal expansion of the screws 1 to 3. The reinforcing fibers 2 exposed by etching serve as a base material for preventing thermal expansion of the hard plating layer 8, thereby preventing the hard plating layer 8 from peeling off.

Therefore, it is possible to maintain high peel strength and stable wear resistance against thermal cycles.

The explanation above has been made in which a part of the piston 3 is made of fiber-reinforced metal and the hard metal fittings 118 are formed thereon. Of course, it is also possible to form the y'r layer 8, or to form the piston pin from a fiber-reinforced metal and form the hard plating layer 8 on its outer peripheral surface. In addition, the reinforcing fibers 2 can be short or long fibers or oval in the form of whiskers 1, and can be etched to expose the reinforcing fibers 2 as a base material to increase the metallic bonding strength with the hard plating N8. is preferable in terms of peel strength. Note that the type and concentration of the etching solution are naturally determined by the material of the light metal base material 1 and the degree of exposure of the reinforcing fibers 2 to be exposed.

[Effects of the Invention] As is clear from the above explanation, according to the present invention, the surface of a fiber-reinforced metal mechanical element formed by combining six metals and reinforcing fibers exhibits the following excellent effects. The reinforcing fibers are etched to expose them, and a plating layer based on the exposed reinforcing fibers is formed on the surface, minimizing the thermal expansion of the fiber-reinforced metal mechanical elements while improving the peel strength of the hard plating layer. and can maintain its wear resistance.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a preferred embodiment of the present invention, and FIG.
The figure is a detailed view of the main part of FIG. 1, and FIG. 3 is a schematic diagram showing the etching process. In the figure, 5 is a reinforcing body as a fiber-reinforced metal mechanical element, 8
is a hard plating layer. Patent applicant: Patent attorney representing Izuda Motors Co., Ltd.
Kinutani Shin Yujoe INc.

Claims (1)

[Claims] 1. Fiber reinforcement characterized by etching the surface of a fiber-reinforced metal machine element formed by combining metal and reinforcing fibers to expose a part of the reinforcing fibers, and forming a plating layer on the surface. Metal mechanical elements.