JP2003027113A - Metal powder with regulated oxygen concentration - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide metal powder having regulated oxygen concentration for controlling the surface wettability of the metal powder, the viscosity in melting the metal powder, the sinterability of the metal powder particles, etc., owing to the increased oxygen concentration of the metal powder. SOLUTION: In the metal powder with regulated oxygen concentration, oxygen is forcedly supplied to an atomization medium when manufacturing the metal powder by gas atomization to regulate oxygen content in the gas-atomized metal powder to 300-3,000 ppm. Further, in the metal powder with regulated oxygen concentration, heat treatment is applied to the above metal powder to regulate oxygen content in the metal powder to 3,000-10,000 ppm.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to the wettability of the surface of metal powder obtained by the high oxygen concentration of the metal powder,
The present invention also relates to a metal powder in which the oxygen concentration is adjusted to control the viscosity when the metal powder is dissolved, the sinterability between the metal powders, and the like.

[0002]

2. Description of the Related Art Conventionally, when atomizing a metal powder, it is usual to make oxygen as low as possible. On the other hand, the technique of adding oxygen to the metal powder is generally performed by heat-treating an inert gas atomized metal powder in the air, or by using water atomization to add oxygen to the surface of the metal powder. .

[0003]

As described above, when oxygen is added to the surface of a metal powder for use, the wettability of the powder surface is utilized by adding oxygen, and the metal having an increased wettability is used. When powder and resin are mixed and used,
Further, when controlling the viscosity of the molten metal when melting the metal powder as a raw material, welding, control of the molten metal flow during spraying,
Controlling the sinterability when sintering metal powders is used, but for powders that have undergone heat treatment in the air or water atomization, it is not possible to supply metal powders that contain an oxygen content suitable for each application. There is a problem that it is difficult.

[0004]

[Means for Solving the Problems] As a result of intensive development by the inventors in order to solve the above-mentioned problems, as a result, a metal powder containing the optimum oxygen concentration for each use is prepared by adjusting the oxygen concentration. To provide powder. The gist of the invention is as follows: (1) When producing a metal powder by a gas atomizing method, oxygen is forcibly added to an atomizing medium so that the oxygen content of the gas atomized metal powder is 500 to 3000.
A metal powder having an adjusted oxygen concentration, which is characterized in ppm. (2) By heat-treating the metal powder described in (1) above, the oxygen content of the metal powder is 3000 to 10,000 p.
pm is a metal powder having an adjusted oxygen concentration.

The present invention will be described in detail below. Originally, when the metal powder was gas-atomized, the amount of oxygen in the metal powder was 100 to 500 ppm, depending on the particle size of the metal powder. This is the oxygen dissolved when the metal powder is dissolved, the oxygen content inevitably contained in the atomized gas,
Further, it is composed of oxygen absorbed and adsorbed during cooling and handling of the metal powder. In general, it is said that the metal powder is better for a product using the metal powder by lowering the oxygen content contained in the metal powder and increasing the cleanliness.

However, when the metal powder is kneaded for a specific purpose, for example, after the metal powder and the resin are wetted to improve the wettability, the metal powder is re-dissolved and the viscosity of the molten metal is adjusted. When using molten metal for welding, controlling the flow of molten metal during welding and spraying, controlling workability of welding and spraying, controlling the sintering rate when sintering and solidifying metal powder, etc. Can control the sintering rate (porosity) by arbitrarily adjusting the oxygen content of the metal powder itself.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION When a metal powder is produced by a gas atomizing method, oxygen is forcibly added to an atomizing medium so that the gas atomized metal powder has an oxygen content of 500 to 3000 ppm, or By heat-treating the powder, the oxygen concentration is adjusted so that the oxygen content of the metal powder is 3000 to 10000 ppm. The metal powder in this case is not particularly limited, but in the present invention, Fe
It is effective for base and Ni base alloys.

[0008]

Example 1 When producing metal powder from a stainless steel having the composition shown in Table 1 by the gas atomizing method, oxygen was forcibly added to the atomizing medium to change the oxygen content of the gas atomized metal powder. 500-3000
It was defined as ppm. The results are shown in Table 1. As shown in Table 1, No. 1-No. No. 4 is a comparative example. 5-N
o. 7 is an example of the present invention. As can be seen from this, No.
1-No. In the comparative example of No. 4, the oxygen concentration is less than 500 ppm and the state of the metal powder has a large number of pores. 5 to No. No. 7 changed the oxygen concentration, and when the oxygen concentration was 500 ppm or more, the wettability between the metal surface and the resin increased, and the resin spread all over the metal, so there was no pore after degreasing and sintering, A true density compact was obtained.

[0009]

[Table 1]

(Example 2) When producing a metal powder from a stainless steel having the composition shown in Table 2 by the gas atomization method, oxygen was forcibly added to the atomizing medium to change the oxygen content of the gas atomized metal powder. Let When a clad tube was produced using this metal powder by a centrifugal casting method, the heated metal powder was directly put into a rotating body and melted while rotating to form a clad. That is, the stainless steel shown in Table 2 was heated on the inner surface of the SS tube to form a clad by centrifugal casting.
A stainless steel having the composition shown in Table 1 was used as a raw material.
No. 1-No. No. 3 is a comparative example. 4 to No.
8 is an example of the present invention. In each of the comparative examples, the oxygen concentration is 50.
It was less than 0 ppm, and pores were observed in the steel made of the metal powder on the inner surface of the clad tube.
o. 4 to No. When 500 ppm or more of the metal powder was used in each of Nos. 8 and 8, the oxide covered the surface and a sound surface having no pore was formed.

[0011]

[Table 2]

(Example 3) In producing a metal powder of a steel having the composition shown in Table 3 by a gas atomizing method, oxygen is forcibly added to an atomizing medium to change the oxygen content of the gas atomized metal powder. It was When this metal powder was used as a thermal spraying (frame) material, the oxygen concentration of the Ni-based self-fluxing alloy most commonly used for flame spraying was changed to perform fusing after flame spraying. As shown in Table 3, No. 1-No.
No. 3 is a comparative example, and in all cases, the oxygen concentration was less than 500 ppm, the flow of the molten metal during fusing was too good, and the sprayed coating dripped, and fusing itself was not possible. On the other hand, No. 4 to No. In each of the examples of the present invention of No. 8, the content was 500 ppm or more, and the flow of the molten metal became poor, and the fusing was possible without the coating dropping.

[0013]

[Table 3]

(Example 4) In producing a metal powder of a steel having the composition shown in Table 4 by a gas atomizing method, oxygen is forcibly added to an atomizing medium to change the oxygen content of the gas atomized metal powder. It was When manufacturing a metal filter using this metal powder, it is necessary to control the density of the metal filter. A sintering experiment was conducted using the metal powders shown in Table 4 and changing the oxygen concentration in order to obtain a filter density of 70% after sintering. No. 1-No. Four
Is a comparative example, in which the oxygen concentration was less than 3000 ppm, the sintering proceeded too much, the density became higher than a predetermined density, and the resistance of the filter was too large. On the other hand, N
o. 5 to No. In each of the nine examples of the present invention, the oxygen concentration was 30.
This is the case where it is at least 00 ppm, and it can be seen that a substantially predetermined sintering density can be obtained.

[0015]

[Table 4]

[0016]

As described above, according to the present invention, it is possible to provide a manufacturing method which is extremely advantageous industrially because it is possible to control the flow of molten metal and sintering, which has not been possible conventionally.

Continued front page    (72) Inventor Kenichi Nakatsuka             No. 3007 Nakajima-Character Nakashima, Himeji City, Hyogo Prefecture               Sanyo Special Steel Co., Ltd. F-term (reference) 4K017 AA03 BA03 BA06 EB01 EK01                       EK08 FA17 FA29                 4K018 BA04 BA13 BC01 BC09 BC10

Claims (2)

[Claims] 1. When producing a metal powder by a gas atomizing method, oxygen is forcibly added to an atomizing medium,
The oxygen content of the gas atomized metal powder is 500-
A metal powder having an adjusted oxygen concentration, which is 3,000 ppm. 2. The heat treatment of the metal powder according to claim 1, whereby the oxygen content of the metal powder is 3000 to 100.
A metal powder having an adjusted oxygen concentration, characterized in that the content is 00 ppm.