JPH03189063A - Ferrous porous reinforced material and combined body of this and non-ferrous metal - Google Patents

Abstract

PURPOSE:To manufacture a combined body having excellent corrosion resistance, wear resistance, heat resistance, etc., by filling up non-ferrous metal having m.p. lower than m.p. of iron, into a porous reinforced material coating fine hole surface layer part of a ferrous porous body with iron oxide, etc. CONSTITUTION:Iron powder or powder containing iron as essential component and material except iron is sintered at about 800 - 1,300 deg.C for about 1 hr to manufacture the porous body having about 45 - 81 vol% porosity. This porous body is held under oxidizing atmosphere at about 100 - 500 deg.C for about 2 hr or humidified and heated with a humidifying-heater and the fine hole surface layer part in the porous body is coated with oxide or hydroxide film having about 0.01 - 10mu to form the ferrous porous reinforced material. Successively, the non-ferrous metal (Mg, Al, etc.) having m.p. lower than m.p. of iron, is filled up into this porous reinforced material to form the combined body. By this method, the combined body having excellent fatigue resistance and creep resistance, etc., is obtd. and available to cylinder block, piston, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a ferrous porous reinforcing material and a composite of the same with a non-ferrous metal.

[Prior Art] Conventionally, for example, cylinder blocks for vehicle engines have been manufactured using alloys such as aluminum by die casting or sand mold casting. but,
Aluminum alloy has poor wear resistance, so an iron liner was inserted inside the cylinder. However, this method has problems such as high cost, increased weight, and problems due to the difference in coefficient of thermal expansion between the liner and the aluminum alloy.

In order to improve this drawback, a composite strengthening method was developed in which porous cast iron containing graphite is impregnated with aluminum to form an iron-aluminum intermetallic compound at the boundary between iron and aluminum (Japanese Patent Laid-Open No. 62-286680). Public bulletin)
Iron-aluminum intermetallic compounds have high hardness and are difficult to process, such as cutting, and also become brittle, resulting in a problem in that their reliability as structural members is impaired.

Aluminum alloys have long been used in pistons to reduce weight, but pistons for engines with a high heat load such as diesel engines have a wear-resistant ring made of Niresist cast iron cast in the first ring groove. However, this wear ring has problems such as high cost and increased piston weight.

Therefore, Japanese Patent Application Publication No. 59-212159 and Japanese Patent Application Publication No. 6
Publication No. 0-11111367 also describes a method in which a metal porous material such as nickel (urethane is plated with metal and then the urethane is removed by heating) is composited into the first ring groove with the aim of improving heat resistance and wear resistance. Japanese Patent Publication No. 58-9394
Although Japanese Patent No. 8 and other publications propose a method of combining a preform made of ceramic fibers into the first ring groove, all methods are expensive.

In addition, magnesium alloy is even lighter than aluminum 273, so it is especially useful for reducing the weight of movable parts.
Although it is desired to be used in terms of output, it has lower heat resistance and wear resistance than aluminum, and has the disadvantage of forming local batteries and corroding when it comes into contact with dissimilar metals, so it has poor durability and reliability. There was a problem that it could not be used for pistons in engines installed in commercially available cars.

[Problems to be Solved by the Invention] The present invention has been made as a result of intensive research to solve these problems.
This led to the discovery and completion of an iron-based porous reinforcing material with excellent wear resistance and corrosion resistance, and a composite using it and non-ferrous metals.

[Means for Solving the Problems] The present invention provides (1) an iron-based porous reinforcing material in which the surface layer of the pores of a porous body made of iron is coated with iron oxide or iron hydroxide; Iron-based porous reinforcement characterized in that the surface of the pores is coated with one or more selected from the group consisting of iron sesquioxide, triiron tetroxide, ferrous hydroxide, and ferric hydroxide. (3) an iron-based porous reinforcing material in which the porous body contains one or more selected from the group consisting of metals other than iron, graphite, silicon, particulate or fibrous ceramic; ) The present invention relates to a composite in which the iron-based porous reinforcing material is filled with a non-ferrous metal having a melting point lower than that of iron.

[Example] The iron-based porous reinforcing material of the present invention is one in which the surface layer of the pores of a porous body is coated with iron oxide or iron hydroxide, and by applying such measures, electrical insulation properties can be improved. Then,
Since there is no direct contact with non-ferrous metals, there is no chance of local batteries forming. In addition, wear resistance can be ensured by the internal barred hole.

The iron-based porous reinforcing material of the present invention is obtained by sintering pure iron or powder containing one or more substances such as silicon, metals other than iron, graphite, or particulate or fibrous ceramics. It is.

When the raw material iron powder is not pure iron, the total content of materials other than iron is preferably about 50% or less of the total weight. Further, other metals such as cobalt, nickel, chromium, molybdenum, tungsten, and manganese may be alloyed with iron or in a mixture.

This iron-based porous reinforcing material is produced by sintering the iron powder and/or a powder mainly composed of iron containing substances other than iron. The sintering temperature is about 800-1300°C, preferably 1
It is preferable that the temperature is 100 to 1200°C and the sintering time is about 1 hour.

If the sintering temperature is too high, the porosity will be small and the matrix metal will not be impregnated. If the sintering temperature is too low, the sintering temperature will not be changed sufficiently, and the porous body, which is the reinforcing material, will be destroyed during impregnation. The porosity of this sintered body is about 45 to 81% (by volume).

Porous bodies as metal filters with a porosity of about 50% have been known for a long time, but the present invention differs from the conventional ones in that it creates a porosity higher than that.

In order to coat the surface layer of the pores with a film of iron oxide or hydroxide, the iron-based porous reinforcing material is heated in an oxidizing atmosphere to
Either by holding the temperature at 500°C, preferably 400°C for about 2 hours, or by applying humidity and temperature using a humidifier.

The thickness of this film is on average 0.01 to 10, preferably 0.
．． It is 5 to 2ρ. If the film is too thick, the composite interface after metal pressing and casting will become brittle, and if it is too thin, the desired effect will not be achieved.

The composite is obtained by filling the iron-based porous reinforcing material with a non-ferrous metal having a lower melting point than iron. In the present invention, non-ferrous metals include non-ferrous metals with melting points lower than iron and their alloys. There are no particular limitations on the type of nonferrous metals, but among them, magnesium, magnesium alloys, aluminum, and aluminum alloys are particularly practical. The aluminum alloy may contain silicon.

Since the properties of the nonferrous metal to be filled differ depending on its components, the type of alloy is selected depending on the purpose.

The iron-based porous reinforcing material has a film of iron oxide or iron hydroxide on the surface layer of its pores, but when it is filled with non-ferrous metal, it remains as iron oxide. However, iron hydroxide is 100-400
It becomes iron oxide at about 0.degree. C., but since water is generated at this time, if heat treatment such as sufficient preheating cannot be performed, it is preferable to use an iron-based porous reinforcing material having an iron oxide film. Since these membranes are electrically insulating layers, they cannot be filled with magnesium or the like to form local batteries, thus making it possible to use magnesium and magnesium alloys as filler metals.

The composite of the present invention has excellent wear resistance and corrosion resistance, and can be used as a low-cost composite for cylinder blocks, pistons, cylinder heads, engine mounts, etc.

EXAMPLES Specific examples of the present invention will be described below with reference to Examples, but the present invention is not limited only to these Examples.

Examples and Comparative Examples Pure iron powder 6 with a particle size of 10 to 150 m+ (average particle size of about 74 mm)
0 g was filled into a sintering container (volume ff 120 m1) by natural filling. This material was heated and sintered at 1150° C. for 1 hour in a flow of Rx gas (Co, N2, H2 mixed gas).

The produced sintered body has a bulk density of 3.0 g/cj and a porosity of approximately 6.
It was a porous body of 2% (by volume).

Next, this porous body was held at 400° C. for 2 hours in an oxidizing atmosphere to form an oxide film. At this time, the thickness of the oxide film is approximately 0. It was Bρ.

This sintered body and a sintered body not subjected to oxide film forming treatment (comparative example) were preheated in advance at 300° C. for 30 minutes, and each was set in a casting mold.

Then, inject molten magnesium (700℃) and
Pressure casting was performed at 0 kg/c.

After cooling, a micrograph of the obtained composite according to the present invention was observed. The photographs are shown in Figs. 1 and 3. These photos were taken using an X-ray microanalyzer (EPMA) (
The photograph was taken using a device used (model EPMA-8705 manufactured by Shimadzu Corporation).

FIGS. 1 and 3 are micrographs of a cross section of the iron-magnesium composite. FIG. 3 is a partially enlarged photograph of FIG. 1. 2 is an explanatory diagram of FIG. 1, and FIG. 4 is an explanatory diagram of FIG. 3. In Figures 1 to 4, the part marked (A) is iron, the part marked (C) is magnesium, and the part (C) is iron oxide.

It can be seen from Figure 1.3 that a layer of iron oxide surrounds the surface of the iron particles with a thickness of about 0.6 mm.

The properties of the composites obtained according to the present invention and comparative examples were investigated. Each measurement method is as follows.

Thickness of Iron Oxide Layer The thickness of the oxide film was measured using EPMA (Model EPMA-8705, manufactured by Shimadzu Corporation).

Corrosion resistance (weight loss) A sample was inserted into a spray of an aqueous solution with a salt concentration of 5±1% (weight ff1) at 35° C. according to the salt spray test method according to JIS Z 2371, and the weight loss was evaluated after 24 hours.

Wear-resistant pin-disk type friction/wear tester (TRl-81
00O, manufactured by Takachiho Seiki ■) was used. In this evaluation, the test disk was rotated at 1270 r, p, m, and a chrome-plated pin was pressed onto the ductile cast iron so that the friction surface pressure was 240) cg/c-. This measures the amount of wear on the test disk over time.

Table 1 shows the measurement results in Examples and Comparative Examples.

From the Examples and Comparative Examples shown in Table 1, it can be seen that the composite using the iron-based porous reinforcing material of the present invention has excellent corrosion resistance, wear resistance, heat resistance, fatigue resistance, creep resistance, etc. .

[Effect of the invention] The composite obtained by the method of manufacturing a composite using an iron-based porous reinforcing material in which the surface layer of the pores is coated with iron oxide or iron hydroxide has corrosion resistance, wear resistance, and heat resistance. It has excellent properties such as fatigue resistance and creep resistance, making it extremely useful as a material for cylinder blocks, pistons, cylinder heads, engine mounts, cylinder heads, etc.

[Brief explanation of drawings]

FIG. 1 is a micrograph of a cross section of an iron and magnesium composite coated with iron oxide. FIG. 2 is an explanatory diagram of FIG. 1. FIG. 3 is a photomicrograph of a cross section of the composite body taken at different magnifications. FIG. 4 is an explanatory diagram of FIG. 3. (Main symbols in the drawings) (a): Iron (b): Magnesium (C): Iron oxide Figure 0pm Figure 2 Figure 1μm

Claims (1)

[Scope of Claims] 1. An iron-based porous reinforcing material in which the surface layer of the pores of a porous body made of iron is coated with iron oxide or iron hydroxide. 2 The surface of the pores is composed of iron sesquioxide, triiron tetroxide, and hydroxide.
The iron-based porous reinforcing material according to claim 1, characterized in that it is coated with one or more selected from the group consisting of iron and ferric hydroxide. 3. The iron-based porous reinforcing material according to claim 1, wherein the porous body contains one or more selected from the group consisting of metals other than iron, graphite, silicon, and particulate or fibrous ceramics. 4. A composite comprising an iron-based porous reinforcing material in which the surface layer of the pores of a porous body made of iron is coated with iron oxide or iron hydroxide, and filled with a non-ferrous metal having a melting point lower than that of iron.