JPH03211202A - Powder for compact using gas atomized metal powder - Google Patents

Abstract

PURPOSE:To obtain a sintered body improved in compressibility and having high density and good mechanical property by blending fine powder, organic binder and liquid lubricant into gas atomized metal powder having large diameter and sticking the fine powder to the powder having large diameter. CONSTITUTION:Par 100 wt parts of the gas atomized metal powder equivalent to stainless steel, etc., composed of relatively large diameter powder, <=3 wt parts ratio in total of the organic binder, such as ethyl cellulose and the liquid lubricant, such as terpinolene, is added. Successively, to this, <= 50 wt parts ratio the fine powder having the average particle diameter of <= 1/2 the large diameter powder is added to form the metal powder for compact. When the fine powder is stuck at comparatively large quantity on the surface of the particle having large diameter powder, fine powders are difficult to aggregate. By improving the fluidity of mixed powder of large diameter powder and fine diameter powder, it can be promoted that both powders are mutually and uniformly diffused at the time of sintering.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a gas atomized powder for compression molding used in powder metallurgy.

(Prior Art) Metal powders such as steel powders have conventionally been produced from molten metals such as molten steel by water spraying methods, gas spraying methods, etc., and used for various purposes. For example, water-sprayed powder used in a powder molding press is filled into a mold space, compressed into a predetermined shape, and molded into a green compact for sintering.

In such a powder compacting press, when compressing water-sprayed powder in a die, a lubricant such as zinc stearate may be added to reduce friction between the powder and the die wall and between the powder particles. is commonly done. As the conventional metal powder for compression molding, water spray powder has usually been used.

(Problem to be solved by the invention) However, since water spray powder is produced by rapid solidification, the powder shape is irregular and non-spherical compared to gas spray powder, and it has good moldability as a powder compact. However, there is a problem that the compressibility is relatively poor.

On the other hand, gas atomized powder has a relatively regular spherical shape that is atomized and solidified in an inert gas, and although it has good compressibility as a powder compact, it has the problem of poor formability. be. Therefore, gas atomized powder is not actually used as metal powder for compression molding.

The problem to be solved by the present invention is to use a gas atomized powder with good compressibility as a metal powder for compression molding, improve the moldability of the gas atomized powder, and further improve the compressibility by adding fine powder. The object of the present invention is to provide a metal raw material powder for compression molding, which allows obtaining a sintered body with good sintered density, mechanical properties, etc.

(Means for Solving the Problems) For this purpose, the metal powder for compression molding using the gas atomized metal powder of the present invention includes 100 parts by weight of the gas atomized metal powder consisting of large-diameter powder having a relatively large particle size, and Powder for compression molding consisting of 50 parts by weight or less of fine powder with an average particle size of 1/2 or less of the average particle size of the large-diameter powder, and 3 parts by weight or less of an organic binder and a liquid lubricant. The method is characterized in that the fine powder is attached to the surface of the large-diameter powder.

The method for producing a powder for compression molding using a gas atomized metal powder of the present invention involves adding 100 parts by weight of a gas atomized metal powder consisting of a large-diameter powder having a relatively large particle size, and 2 parts by weight of a gas-atomized metal powder consisting of a relatively large particle size,
Using a compression molding powder consisting of 50 parts by weight or less of fine powder having an average particle size of 1/2 or less, and a total of 3 parts by weight or less of an organic binder and a liquid lubricant, The method is characterized in that the fine powder is added after the binder and the liquid lubricant are added.

The gas atomized metal powder is used because it can improve the compressibility of the powder compact and increase the mechanical strength of the sintered body obtained by sintering.

As the organic binder, ethyl cellulose, polyvinyl alcohol, etc. are used, but the organic binder of the present invention is not limited to these. By adding an organic binder, the moldability of the gas atomized powder is improved, and the metal The moldability of the powder is improved.

As the liquid lubricant, terpineol, oleic acid, etc. are used, but the liquid lubricant of the present invention is not limited to these lubricants.

Both the organic binder and the liquid lubricant are essential additives, and the reason why the total amount of the organic binder and liquid lubricant is 3 parts by weight or less for 100 parts by weight of the gas atomized metal powder is because it exceeds 3 parts by weight. This is because compressibility is excessively reduced.

The reason for adding fine powder with an average particle size of less than half is to insert fine powder with substantially the same composition into the gaps between large particles of gas atomized metal powder, and to ensure uniform diffusion during sintering. This is to improve compressibility.

In addition, in the compression molding powder of the present invention, when fine powder is added after adding an organic binder and a liquid lubricant to a large-diameter powder of gas atomized metal powder, a relatively large amount of fine powder is deposited on the particle surface of the large-diameter powder. can be attached to. This is achieved by wetting the particle surface of the large-diameter powder with an organic binder and liquid lubricant, and attaching as much fine powder as possible around the large-diameter powder particles to make it difficult for the fine powder to aggregate. This is to improve the fluidity of the mixed powder of the large-diameter powder and the fine powder, and to promote uniform diffusion of the large-diameter powder and the fine powder into each other during sintering.

(Example) Examples of the present invention will be described below.

1" mouth.

The composition is Coo, 012wt% (hereinafter simply referred to as 1%), Si: 0.85%, Mn: 0°14%, P
: 0.005%, S: 0.001%, Ni: 0.05%
, Cr: 12.5%, balance Fe stainless steel (
A gas atomized powder was obtained from a molten metal (equivalent to SUS430L) by a gas atomization method.

After classifying this gas atomized powder into 160 meshes, 0.5 parts by weight of ethyl cellulose as an organic binder and terpineol as a liquid lubricant were added to 100 parts by weight of the gas atomized powder. After that, -350
Carbon classified into mesh particles with an average particle size of 5.7 μm (
1 part by weight of fine powder of natural graphite was added. In this case, fine powder made of carbon adhered to the surface of the large diameter particles of the stainless steel powder. This mixed powder is referred to as Example 1.

In addition, a mixed powder of Comparative Example 1 was prepared using a water spray powder having the same composition as the gas spray powder in place of the gas spray powder. Ethyl cellulose, terpineol, and carbon were added in the same amounts as in Example 1. Table 1 shows the results of compression molding these powders with a pressure cuff of t/cm''.

(hereinafter referred to as margin) As shown in Table 1, Example 1 has a higher green density (and a relatively smaller Rattler value) than Comparative Example 1. Compared to Comparative Example 1, the sintered density was higher (and the structure was more uniform, indicating that the attached fine powder was relatively homogeneously diffused into the large diameter powder. From this, when gas atomized powder was used, It was found that compression molding with the same composition and under the same conditions had better compressibility and moldability than when water spray powder was used.

The composition of Fuse is C: 0.013%, Si: 0.77%, Mn:
0.13%, P: 0.004%, S: 0°001%, N
i: 13.42%, Cr: 17.12%, Mo: 1.
A gas atomized powder was obtained from a molten metal of 94% stainless steel (SUS316L) by a gas atomization method.

After classifying this gas atomized powder into 160 meshes, methylcellulose as an organic binder and ethylene glycol as a liquid lubricant were added, and then fine powder of Fe-4B, which was classified into -400 meshes, was added to 100 parts by weight of the gas atomized powder. Part by weight was added.

This mixed powder was used as Example 2, and was molded into a pressure cuff t/c.
Compression molding was performed at

In addition, a mixed powder of Comparative Example 2 was prepared using a water spray powder having the same composition as the gas spray powder in place of the gas spray powder. This mixed powder was classified into 1100 meshes and compression molded using the usual process of mixing a solid lubricant. This result is the second
Shown in the table.

As shown in Table 2, it can be seen that the compact of Example 2 has a higher green density and a relatively smaller Rattler value than Comparative Example 2. This shows that the use of an organic binder and a liquid lubricant improves the moldability and compressibility of the gas atomized powder.

Mitate ■1 Composition is C: 0.012wt%, Si: 0.80%, M
n: 0.02%, P: 0.05%, S: 0.01%, N
i: Permalloy (F) consisting of 47.00%, balance Fe
A gas atomized powder was obtained from a molten metal of e-Ni alloy) by a gas atomization method.

After classifying this gas atomized powder into 160 meshes, 0.5 parts by weight of ethyl cellulose as an organic binder and terpineol as a liquid lubricant were mixed with 100 parts by weight of the gas atomized powder, and 10% of permalloy fine powder was added to this.
Parts by weight were added and mixed. The obtained powder was designated as Example 3.

Regarding the powder of Example 3, Japanese Industrial Standards (JIS-2)
2502) was conducted.

The results are shown in Table 3.

In addition, the value shown in the (φ5) column of flow rate is JIS-225
The results obtained by changing the funnel diameter to φ5 in the test method No. 02 are shown below.

(Hereinafter referred to as margins) In Table 3, Comparative Example 3 shows the fluidity of a case in which fine powder was added to a large-diameter gas atomized powder, but no organic binder or liquid lubricant was added.

Comparative Example 4 uses water atomized powder instead of gas atomized powder.
After classifying into 0 mesh, add 1 part of zinc stearate to it.
The fluidity of the mixed powder added in parts by weight is shown.

In the powder of Example 3, fine powder was observed to adhere to the surface of the large diameter gas atomized powder, whereas in Comparative Example 3, no fine powder was observed to adhere. Furthermore, in Example 3, the fluidity was that of Comparative Example 3.
And it was better than Comparative Example 4. Example 3 here
As shown in Figure 1, 10 parts by weight of fine powder was used for 90 parts by weight of large-diameter gas atomized powder. This is because the green powder density takes a maximum value of about 7.50 g/cm'', and as the proportion of fine powder increases, the green powder density gradually decreases.

Here, the large-diameter gas atomized powder and the fine powder are each used at a ratio of 50 parts by weight, resulting in a compacted powder density approximately equivalent to that of the water atomized powder.

(Effects of the Invention) As explained above, according to the compression molding powder using the gas atomized metal powder of the present invention, a predetermined amount of an organic binder and a liquid lubricant are added to the large diameter gas atomized metal powder. In addition, by adhering the fine powder to the surface of the large-diameter powder, there is an effect that a metal powder with good fluidity, moldability, and compressibility can be obtained. Therefore, by compression molding the metal powder for compression molding of the present invention and sintering the obtained molded body,
By taking advantage of the characteristics of the gas atomized powder, a sintered body with excellent mechanical strength etc. can be obtained.

[Brief explanation of drawings]

FIG. 1 is a characteristic diagram showing the relationship between the addition ratio of large diameter powder and fine powder and green powder density in gas atomized powder according to an example of the present invention.

Claims (2)

[Claims] (1) 100 parts by weight of gas atomized metal powder consisting of large-diameter powder with a relatively large particle size, and 50 parts by weight or less of fine particles having an average particle size of one-half or less of the average particle size of the large-diameter powder. powder and
A compression molding powder comprising an organic binder and a liquid lubricant in a total amount of 3 parts by weight or less, wherein the fine powder is attached to the surface of the large diameter powder. Powder for compression molding used. (2) 100 parts by weight of gas atomized metal powder consisting of large-diameter powder with a relatively large particle size, and 50 parts by weight or less of fine particles having an average particle size of one-half or less of the average particle size of the large-diameter powder; powder and
Using a compression molding powder consisting of a total amount of an organic binder and a liquid lubricant of 3 parts by weight or less, adding the organic binder and the liquid lubricant to the large-diameter powder, and then adding the fine powder. A method for producing powder for compression molding using gas atomized metal powder, characterized by: