JPH03189064A - Iron-non-ferrous metal combined body and manufacture thereof - Google Patents

Abstract

PURPOSE:To manufacture an iron - non-ferrous combined body having heat resistance and wear resistance by sintering iron powder under low oxygen atmosphere to form a porous body and filling up the non-ferrous metal having m.p. lower than m.p. of iron into pores so as not to form intermetallic com pound. CONSTITUTION:The iron powder (pure iron powder, alloy iron powder, etc., having about 1 - 100mu particle diameter) is naturally packed into a vessel for sintering and sintered under reducing atmosphere to form the porous body having about 45 - 81 vol% porosity and about 1.5 - 4.3 g/cm<3> bulk density. Successively, the non-ferrous metal (Al, Mg, Zn, etc.) having m.p. lower than m.p. of iron, is filled up into the bores in the porous body with the ordinary method so as not to form the intermetallic compound at boundary between the porous body and non-ferrous metal at this time. By this method, the com bined body having excellent characteristics of rigidity, corrosion resistance, creep resistance, etc., is obtd. and available to the field of car engine, etc.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for manufacturing a ferrous-nonferrous metal composite.

[Conventional technology]

With the need for lighter vehicles and higher engine output, aluminum alloys have been increasingly used in place of steel. However, although aluminum alloys have the advantage of being lightweight, they have problems such as a lack of heat resistance, wear resistance, and rigidity. As a means of solving these problems, ceramic fiber-impregnated aluminum pistons (Japanese Patent Application Laid-Open No. 1983-93948) and nickel porous bodies (however, chemical copper plating is applied to urethane porous bodies) are available as a means to counter the lack of wear resistance of aluminum alloy pistons. Later, a composite piston (Japanese Unexamined Patent Application Publication No. 1983-1970) was developed using a composite piston (nickel plated and then burnt out of the urethane porous material).
Publication No.-212159 and JP-A-60-118367
(Japanese Patent Application Laid-Open No. 6-2010), or an aluminum block made of cast iron fiber and aluminum to form an intermetallic compound as a substitute for the cylinder block liner (steel) (Japanese Patent Application Laid-Open No.
2-288860) and the like are known.

However, these conventional techniques have the disadvantage that the reinforcing materials shown in the example of pistons are expensive, and the generation of intermetallic compounds in the example of cylinder block liner replacement is hard and brittle, making it difficult to process. In addition to these problems, there are other problems such as the difficulty of setting conditions to form a certain thin film of intermetallic compounds.

[Problems to be Solved by the Invention] As a result of intensive research by the present inventors to solve the problems of the prior art as described above, we have found that a material with excellent physical properties such as heat resistance, abrasion resistance, and rigidity, , low manufacturing cost steel.
Discovered a non-ferrous metal composite with a melting point lower than iron and its manufacturing method.
The present invention has now been completed.

[Means for Solving the Problems] The present invention provides (1) adding a nonferrous metal having a melting point lower than that of iron to the pores of a porous body obtained by sintering iron powder in a low oxygen or reducing atmosphere; A heat-resistant and wear-resistant iron-nonferrous metal composite characterized in that the boundary between the body and the metal is filled without forming an intermetallic compound, and iron powder is sintered in a low oxygen or reducing atmosphere. A heat-resistant and wear-resistant iron-nonferrous material characterized in that the pores of the porous body obtained by the above process are filled with a nonferrous metal so that no intermetallic compound is formed at the boundary between the porous body and the nonferrous metal. The present invention relates to a method for manufacturing a metal composite.

[Function and Examples] The composite of the present invention is excellent in heat resistance and wear resistance and is economically excellent in the field of mechanical engineering, particularly in the field of automobile engines.

The composite of the present invention is made by die-casting or molten metal forging of aluminum or other non-ferrous metals with a lower melting point than iron, or their alloys, into a bar body obtained by sintering naturally filled iron powder in a low-oxygen or reducing atmosphere. The composite is impregnated by a method or the composite is first formed and cast to prevent the formation of intermetallic compounds at the interface between iron and the nonferrous metal or its alloy.

The iron powder used in the present invention is, for example, pure iron powder, alloyed iron powder, composite steel powder, etc., with a particle size of about 1 to 1000 m+, preferably 10 to 150 m+. The iron component may be pure iron, or may contain components such as chromium, nickel, and copper. Sintering is performed in a reducing atmosphere, such as a mixed gas atmosphere of carbon oxide, hydrogen, and nitrogen, or an oxygen
It is necessary to carry out the above-mentioned air flow containing less than % by volume. If the atmosphere is not reducing, the surface of the iron particles will be oxidized during sintering, and a porous sintered body will not be formed.

The porosity of this porous body is preferably about 45 to 81% (by volume, hereinafter the same), and particularly preferably about 65 to 75%. If the porosity is higher than this, characteristics such as sufficient wear resistance cannot be changed, and the bar body will buckle when molten metal is forged under pressure. If it is lower than this range, impregnation becomes difficult. The bulk density of this material is preferably about 1.5 to 4.3 g/cj
, particularly preferably about 2.5 to 3.0 g/-.

In order to obtain a porous body within this range, the various iron powders are preferably filled naturally, using a vibrator or the like as necessary, prior to sintering. At this time, special care must be taken not to perform pressure filling.

The filler metal is a non-ferrous metal with a lower melting point than iron, such as aluminum, magnesium or zinc, or an alloy thereof. In the present invention, nonferrous metals having a melting point lower than iron include alloys thereof, and these are collectively referred to as "nonferrous metals."

From the viewpoint of durability, magnesium is preferably used in environments other than corrosion-promoting environments where moisture is present in order to prevent corrosion due to the formation of local batteries with iron.

The non-ferrous metal may be filled by a conventional method, but it is important that no iron-non-ferrous metal compound is substantially generated at the interface between the iron and the non-ferrous metal. To this end, when filling a bar with molten nonferrous metal, it is sufficient to do so in as short a time as possible to minimize the contact time with oxygen in the air. No formation of intermetallic compounds is observed in die casting or molten metal forging. Furthermore, if slow filling is required for the manufacture of parts with complex shapes, filling may be carried out under reduced pressure or vacuum or under nitrogen substitution. If this condition is removed, an intermetallic compound layer may be formed in the boundary layer between iron and metal.

The composite obtained in this way has superior machinability compared to the conventional one in which intermetallic compounds are formed in the boundary layer of iron and aluminum, and it does not require manufacturing control to control the amount of intermetallic compounds formed. It is excellent in that it can be easily replaced with a composite material with excellent heat resistance and abrasion resistance without causing any damage.
Extremely useful for pistons, cylinder block liners, cylinder heads, engine mounts, etc.

The present invention will be described below with reference to Examples, but the present invention is not limited thereto.

Example 1 60 g of cast iron powder with a particle size of 10 to 150 m+ (average particle size of about 74 mm) was naturally filled into a sintering container (volume Q20 ml). This material was heated and sintered at 1150° C. for 1 hour in a flow of Rx gas (a mixed gas of carbon oxide, nitrogen, and hydrogen). The produced sintered body was a porous body with a bulk density of 3.0 g/cj and a porosity of about 62%.

This sintered body was preheated to about 100 to 400°C and set in a cast iron mold. Next, aluminum alloy [composition: JIS AC8A (8111-13% by weight, MgO, 7-1.3% by weight, N10.8-1.5
A molten metal containing aluminum containing % by weight was injected under pressure.

The injection pressure at this time was about 600 kg/c-. After cooling, it was taken out from the mold to obtain a composite of the present invention.

The cross section of the obtained iron-aluminum composite was observed using an electron microscope, and the concentrations of iron and aluminum were measured. The results are shown in Figures 1-4.

These photographs and density measurements were carried out using an X-ray microanalyzer (EPMA) (the device used was EPMA-8705 model manufactured by Shimadzu Corporation).

Figures 1 and 3 are electron micrographs of the cross section of the iron-aluminum alloy composite, with Figure 1 containing the iron concentration line and Figure 3 containing the aluminum concentration line. be. Figure 2 is an explanatory diagram of Figure 1, Figure 4 is an illustration of Figure 3.
It is an explanatory view of a figure. In Figures 1 to 4, (the field portions are iron and the mountain portions are aluminum alloy). In Figure 1.2, (1) shows the iron concentration line measured according to the scanning line (3) in the figure. In Figure 3.4, (2) shows the aluminum concentration line measured according to the scanning line (3) in the figure. Note that FIG. 5 is an electron micrograph of a cross section of an iron-aluminum alloy composite in a conventional example, and FIG. 6 is an explanatory diagram thereof. In Figure 5.6, (a), mountain),
(1), ('2J and (3) represent the same as above, and (C) represents an intermetallic compound (iron-aluminum alloy intermetallic compound) generated at the boundary of iron-aluminum alloy. Section 5.6 As is clear from the figure, in the case of conventional iron-aluminum alloy composites, a clear plateau is observed in the iron concentration line at the part corresponding to the intermetallic compound, and a clear plateau is observed in the aluminum concentration line at the part corresponding to the intermetallic compound. On the other hand, as is clear from Figures 1 to 4, in the case of the iron-aluminum composite of the present invention, the iron concentration line is sharp between iron and aluminum. Similarly, the concentration line for aluminum also changes rapidly and no plateau is observed.Therefore, it can be seen that no intermetallic compound is generated in the iron-aluminum alloy composite.

The amount of wear, heat resistance, and rigidity of the obtained composite were measured. The measurement and evaluation methods for each item are as follows.

Heat resistance/rigidity: Metal material tensile test method (JIS
z2241).

A 1OTon universal testing machine (REH-10 manufactured by Shimadzu Corporation) was used as the testing machine.

Wear resistance: Pin-disk type friction and wear tester (
The test was carried out using a TRI-8100O1 (manufactured by Takachiho Seiki).

In this evaluation, the test disk was rotated at 127 degrees r, p, m, and a chromium-plated ductile cast iron bottle was pressed against it with a friction surface pressure of 240 kg/cd for 100 hours. This is to measure the amount of wear of the test disc against the friction time. 80 for lubrication
Engine oil heated to ℃ was used.

The measured data are shown in Table 1 and FIG.

FIG. 7 is a graph showing the relationship between temperature and strength of the composite of the present invention and the aluminum alloy alone. In Figure 7, the vertical axis represents the strength kg/a+m2, and the horizontal axis represents the test temperature (
'C).

Example 2 An iron-pure aluminum composite was obtained in the same manner as in Example 1 except that pure aluminum was used instead of the aluminum alloy used in Example 1.

The measured data are shown in Table 1 and FIG.

Comparative Example 1 For comparison, aluminum alloy (AJIS AC8A
) is also measured separately in Tables 1 and 7.
As shown in the figure.

Table 1 From Table 1, it can be seen that the composites of the present invention (Examples 1 to 2) are superior in abrasion resistance and rigidity to those made of aluminum alone (Comparative Example 1). FIG. 7 also shows that the composites of the present invention (Examples 1 and 2) have higher strength than the aluminum alloy alone (Comparative Example 1) even at high temperatures.

As described above, it can be seen that the iron-aluminum alloy composite obtained by the present invention has excellent heat resistance, wear resistance, and rigidity.

[Effects of the Invention] As described above, the composite made of iron and a nonferrous metal whose melting point is lower than that of iron or an alloy thereof obtained by the method of the present invention has not only heat resistance, wear resistance, and rigidity, but also corrosion resistance, creep resistance, and resistance. It has excellent properties such as fatigue resistance and low manufacturing cost, and can be widely used in various fields including the automobile industry.

[Brief explanation of drawings]

FIG. 1 shows an electron micrograph of a cross section of the iron-aluminum alloy composite of the present invention and an iron concentration line measured along the scanning line. FIG. 2 is an explanatory diagram of FIG. 1. FIG. 3 is an electron micrograph of a cross section of the iron-aluminum alloy composite of the present invention and an aluminum concentration line measured along the scanning line. FIG. 4 is an explanatory diagram of FIG. 3. FIG. 5 shows an electron micrograph of a cross section of an iron-aluminum alloy composite in a conventional example and concentration lines of iron and aluminum measured along the scanning line. FIG. 6 is an explanatory diagram of FIG. 5. FIG. 7 is a graph showing changes in strength at various temperatures of an iron-aluminum alloy composite (Example 1), an iron-pure aluminum composite (Example 2), and an aluminum alloy (Comparative Example 1). (Main symbols in the drawing) (1): Iron concentration line (2) Nialuminum concentration line (3): Scanning line (■; Iron mountain) Nialuminum alloy (C): Iron-aluminum alloy Intermetallic compound No. 1 Figure 10 μm No. Diagram opm Diagram 2a Diagram 4 Iron Diagram 5μm Diagram 27・;Example 1 0: Example 2 Method) % formula % 2. Name of the invention Iron-non-ferrous metal composite and its manufacturing method 3. Relationship with the amended case Patent applicant address 1-1 Daihatsu-cho, Ikeda-shi, Osaka Name
(296) Daihatsu Motor Co., Ltd. Representative Osuka 2nd Department 4 Agent 540 Address 2-2-22 Tanimachi, Chuo-ku, Osaka 5 Date of amendment order March 27, 1990 (shipment date) Procedural amendment ( Voluntary) April 19, 1990 6 Subject of amendment fl) Contents of amendment in column 7 “Brief explanation of drawings” of the specification ” is corrected to ``This is an electron micrograph of a metal structure in a cross section.'' (2) On page 13, lines 11 to 12, "This is a concentration line of a cross section." is replaced with "This is an electron micrograph of a metal structure in a cross section." ” he corrected. (3) On page 13, lines 14 to 16, "This is a concentration line of a cross section." is corrected to "This is an electron micrograph of a metal structure in a cross section." 2. Name of the invention Iron-nonferrous metal composite and its manufacturing method 3. Relationship with the amended case Patent applicant address 1-1 Daihatsu-cho, Ikeda-shi, Osaka Name
(296) Daihatsu Motor Co., Ltd. Representative Osuka 2nd Department 4 Agent 540 Address 2-2-22 Tanimachi, Chuo-ku, Osaka Subject of 5 amendments tll 6 amendments in column ``Detailed Description of the Invention'' of the specification Contents (1) On page 8, line 19 and page 9, line 9 of the specification, the words "in cross section" are corrected to "metallic structure in cross section."that's all

Claims (1)

[Claims] 1. The pores of a porous body obtained by sintering iron powder in a low oxygen or reducing atmosphere are filled with a nonferrous metal whose melting point is lower than that of iron, and the porous body and the nonferrous metal are bonded together. Heat-resistant and wear-resistant iron characterized by no intermetallic compounds forming at boundaries.
Non-ferrous metal composites. 2. A nonferrous metal having a melting point lower than that of iron is added to the pores of a porous body obtained by sintering iron powder in a low oxygen or reducing atmosphere, so that no intermetallic compound is formed at the boundary between the porous body and the nonferrous metal. 1. A method for producing a heat-resistant and wear-resistant ferrous-nonferrous metal composite, which is characterized by filling the composite material in the following manner.