JPS6119703A - Preparation of copper infiltrated ferrous sintered body - Google Patents

Abstract

PURPOSE:To obtain a sintered body having stable quality by preventing the shift of a matrix and an infiltration material, by integrally molding a molded body of a copper powder on a molded body constituted of a ferrous metal powder and simultaneously applying sintering and infiltration to the resulting composite molded body at a specific temp. CONSTITUTION:A ferrous sintering powder (for example, a powder prepared by adding a predetermined amount of a copper powder and a graphite powder to an iron powder) being a matrix is moled in a mold to form a ferrous molded body 11. Subsequently, a copper powder molded body 12 comprising copper or a copper alloy (for example, an alloy prepared by adding a Mn powder and an iron powder to a copper powder) being an infiltration material is molded on the ferrous molded body by using a mold under pressure lower than that at the molding time of the ferrous molded body. To this composite molded body 10, sintering and infiltration are simultaneously applied at 1,000-1,250 deg.C. By this method, a copper infiltrated ferrous sintered body having stable quality is prepared inexpensively.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing an iron-based sintered body infiltrated with copper or a copper alloy.

[Conventional technology]

Sliding members such as valve seats of internal combustion engines are required to have wear resistance and high strength, and generally, iron-based sintered bodies infiltrated with copper or the like are used.

Conventionally, an iron-based sintered body infiltrated with copper or a copper alloy is made of a base material, an iron-based sintered body or powder compact 21, and an infiltration material, copper or copper alloy ( The powder compacts 22 (hereinafter referred to as steel) are separately molded, and a copper powder compact 2 as an infiltration material is placed on top of the iron-based sintered compact or powder compact 21 to be infiltrated.
2 and heat it to perform infiltration or sintering/infiltration. - [Problems to be solved by the invention] In the above manufacturing method, the copper powder compact 22 as the infiltrant is not sufficiently fixed on the iron-based sintered body or the powder compact 21 as the base material. Therefore, when infiltrating or sintering without moving in a continuous sintering furnace, the base material and the infiltrant material may become misaligned, resulting in poor infiltration. Further, since the strength of the copper powder molded body 22, which is an infiltration material, is low, it is difficult to automate the process of placing the copper powder molded body 22 on the three base materials. Furthermore, in the case of irregularly shaped parts.

There were cases in which it was impossible to mold the copper powder compact 22, or even if it could be molded, it could not be placed on the base material.

An object of the present invention is to provide a method for manufacturing a copper-infiltrated iron-based sintered body, which allows simultaneous sintering and infiltration without causing the base material and the infiltrant to shift. be.

[Means for solving problems]

As a means for solving the problem described in -I-, the present invention provides a first layer in which iron-based metal powder constituting an iron-based sintered body as a base material is molded in a mold, and then this first layer On top of this, a second layer made of copper or copper alloy as an infiltrant is integrally molded with a mold at a pressure lower than the pressure during molding of the first layer to form a composite molded body, and this composite molded body is It is characterized by simultaneous sintering and infiltration at a temperature of 100 to 1,250 °C.

Powders for iron-based sintered bodies, which are lumber materials, are those normally used for this type of sintered bodies, such as iron powder with 2% copper powder and 0.8% graphite powder. Mixed flour made by adding
A mixed powder made by adding 3% copper powder, 2% nickel powder, and 0.8% graphite powder to iron powder can be used. (
In the present invention, % represents weight % unless otherwise specified.

) Copper or copper alloy powder can be used as the infiltrant,
As the copper alloy powder, for example, a copper alloy powder consisting of 4% Mn, 4% Fe, and the balance Cu, a copper alloy powder consisting of C00.5%, 4% Fe, and the balance Gu, etc. can be used.

Copper-infiltrated iron-based sintering can be achieved by changing the ratio of iron-based sintered body powder, which is the base material, and copper powder, which is the infiltration material, and by appropriately adjusting the porosity and infiltration amount of the sintered body. The properties of the aggregate can be easily changed.

The pressure when stacking the copper powder, which is the infiltration material of the second layer, on the iron-based molded body, which is the base material of the first layer, and molding it integrally is
The reason why the pressure is lower than the pressure at which the iron-based sintered body powder of the layer is molded is to prevent the iron-based molded body of the first layer from being deformed when molding the second layer.

The temperature for simultaneous sintering and infiltration can be selected from a range of 1,100 to 1,250°C.

1. If the temperature is below +00°C, the sintering of the iron-based powder compact will be insufficient, and some copper alloys will not be infiltrated. ,2
If it exceeds 50°C, there is a problem of contamination of the furnace due to copper vapor, so the temperature needs to be below 1.250°C.

[Effect]

As the first layer, powder for an iron-based sintered body, which is an ST material, is molded, and on top of that, copper powder, which is an infiltration material, is layered and molded as a second layer to form a composite molded body 10. It has become
There is no misalignment between the iron-based compact 11, which is the base material, and the copper powder compact 12, which is the infiltration material. In addition, since the copper powder is layered and molded using the same mold, molding can be performed without being affected by the complicated shape of the top surface of the iron-based molded body 11 of the first layer, and the molding pressure at that time can be reduced. Since the pressure is lower than that used when molding the iron-based molded body 11, the shape of the first layer of iron-based molded body +1 does not collapse.

[,’JL k example] This will be explained in detail below using examples.

2% electrolytic copper powder (-
100 mesh) and 0.8% natural graphite (average particle size lOt) were added and mixed for 30 minutes using a V-type mixer to obtain a powder for iron-based sintered bodies.

Next, a mold having a molding cavity with an outer diameter of 3 [f] and an inner diameter of 30 mm is filled with the powder for the iron-based sintered body, and the pressurizing surface of the upper mold punch forms the iron-based molded body 11 as shown in FIG. Using a mold with a stepped top surface, 6
Pressure molding was performed at a molding pressure of ton/cm' to a height of 61!1 m. Then, the first
Cu-45M is applied as an infiltrant on the iron-based molded body 11 of the layer.
Atomized copper alloy powder (-100m) consisting of n-4% Fe.

Filled with X5 parts by weight per 100 parts by weight of powder for iron-based sintered bodies, and pressed together using the above-mentioned upper die punch at a molding pressure of 4 ton/cm'. A second layer of copper powder molded body 12 was formed by pressure molding, and an integrated composite molded body consisting of iron-based molded body 11 and copper powder molded body 12 as shown in FIG. 1 was obtained.

This composite molded body 10 was sintered and infiltrated at 150° C. for 30 minutes in an ammonium decomposition gas atmosphere to obtain a copper-infiltrated iron-based sintered body.

〔Effect of the invention〕

As described above, the manufacturing method of the present invention is to form the powder for iron-based sintered body as the base material as the first layer, and overlay and shape the copper powder as the infiltration material as the second layer. Since the composite molded body is made, there is no possibility that the iron-based molded body that is the base material and the copper powder molded body that is the infiltrant material are misaligned, and it is possible to obtain a copper-infiltrated iron-based sintered body of stable quality. Furthermore, the process of stacking the copper powder molded body as an infiltration material on the iron-based sintered body or molded body as the base material is no longer necessary, and even for irregularly shaped parts, it is possible to mold the copper powder molded body or not. , the problem of sometimes not being able to be placed has been resolved. Furthermore, sintering and infiltration can be performed simultaneously, simplifying the process. ” Manufacturing costs can be reduced for these reasons mentioned above.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of a composite molded body showing an embodiment of the present invention, and Fig. 2 is an example in which a copper powder molded body as an infiltration material is placed on a conventional sintered body or molded body of steel. FIG. In the figure, 10... Composite molded body 11... Iron-based molded body 12.
・・Copper powder compact

Claims (1)

[Claims] As the first layer, iron-based metal powder constituting the iron-based sintered body, which is the base material, is molded, and then a second layer made of copper or copper alloy powder, which is the infiltration material, is formed on top of this first layer. A composite molded body is formed by integral molding at a pressure lower than the pressure during molding of the first layer, and this composite molded body is simultaneously sintered and infiltrated at a temperature of 1,100 to 1,250°C. A method for producing a copper-infiltrated iron-based sintered body, characterized by: