JPH06330110A - Production of metal or alloy powder - Google Patents

Abstract

PURPOSE:To provide the production method of a metal or alloy powder which has a low oxygen content and is used for the powder metallurgy, injection molding, etc. CONSTITUTION:At the time of producing a metal or alloy powder by the water atomizing method, the molten metal or alloy is pulverized by allowing it to flow down from a nozzle and injecting into it high pressure atomized water contg. an oxidation inhibitor from an injection nozzle. Since the powder having a low oxygen content can be produced by using this method, the need for any special post treatment of the metal or alloy powder thus produced is eliminated and therefore the powder can be used as it is for injection molding, sintering, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a metal or alloy powder having a low oxygen content, which is mainly used for powder metallurgy, injection molding and the like.

[0002]

2. Description of the Related Art As is well known as a method for producing metal or alloy powder, a water atomizing method is a method in which molten metal or alloy is made to flow down from a container through a nozzle, and high-pressure water is sprayed from this nozzle to melt the metal. Alternatively, it is a method of pulverizing an alloy to produce a powder.

However, even if an attempt is made to produce a powder having a low oxygen content for a metal or alloy which is easily oxidized at a high temperature by this water atomizing method, when a high temperature molten metal or alloy comes into contact with water, It has been difficult to lower the oxygen level of the powder because it decomposes into oxygen and hydrogen and produces oxides that are believed to result from the reaction of this oxygen with the metal or alloy.

As an attempt to lower the oxygen level, water used in the atomizing method is bubbled with an inert gas such as argon or nitrogen as described in JP-A-2-290002, or dissolved in water by a reduced pressure treatment. There are ways to reduce oxygen, but it has not been sufficient to reduce the oxygen level in powders.

Further, since the metal or alloy powder having a high oxygen content produced by the conventional water atomizing method as described above cannot be used as it is, it must be further reduced. This reducing treatment requires reducing substances such as hydrogen and carbon monoxide, and since the powders are heated to a high temperature, the powders are in a sintered state and must be crushed. The stay is reduced. Further, as for the equipment, there is a drawback that a heating equipment, a powder moving equipment, a reducing gas treatment equipment, a crushing equipment and the like are required, and the manufacturing cost becomes high.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a powder of metal or alloy having a low oxygen content, which cannot be produced by the conventional water atomizing method.

[0007]

In order to solve the above-mentioned problems, the present invention adds an oxidation inhibitor to water used in the atomizing method, and then passes a metal or alloy obtained by melting the water from a container through a nozzle. It is characterized in that it is made to flow down and high-pressure water is jetted from this to pulverize the molten metal or alloy to produce powder.

[0008]

In other words, since the oxidation inhibitor added to the water used in the atomizing method is considered to suppress the oxidation reaction between oxygen and the metal or alloy, even if the metal or alloy is easily oxidized at high temperature, It has become possible to produce metal or alloy powders with a low oxygen content.

Here, the oxidation inhibitor in the present invention is a substance having an action of suppressing the oxidation of a metal or alloy at high temperature,
There are organic substances and inorganic substances, and as the organic substances, there are aniline, pyridine, cyclohexylamine, octadecylamine and other aliphatic amines, aromatic imidazoles, aromatic urea and other aromatic amines, and amines. There are sulfides such as amides, thiophenol and thiocresol, aldehydes and ketones, and inorganic substances include chromates, polyphosphates, silicates, molybdates and tungstates. 1 or 2
Mixtures of more than one can be used.

The amount of the oxidation inhibitor added to water is 0.1.
% To 5%. The reason for this is that if it is 0.1% or less, the effect of suppressing oxidation is small, and if 5% or more is added, the effect is saturated and the cost becomes high. The preferred range is 0.2
~ 1%.

The metal or alloy in the present invention is a metal or alloy that is easily oxidized at high temperature, such as iron or silicon steel,
Examples include iron-based alloys such as stainless steel and Mn-containing steel, chromium, chromium-based alloys, titanium, titanium-based alloys, nickel and nickel-based alloys.

The present invention has made it possible to produce a powder having a low oxidation content even in a metal or alloy which is easily oxidized at a high temperature and which cannot be produced by the conventional water atomizing method. Also, regarding the manufacturing equipment, since it is only necessary to add an oxidation inhibitor to the water used in the atomizing method, no special equipment is required at all, and there is an advantage that the manufacturing equipment of the conventional water atomizing method can be used as it is. . For example, iron powder, which is used in large quantities as an industrial material, silicon steel, which is important as a magnetic material, and manganese-containing iron alloy, cannot be used as it is because the powder is highly oxidized when manufactured by the conventional water atomization method. . However, since the powder produced according to the present invention is suppressed in oxidation and has a low oxygen content, it can be directly used for injection molding, sintering, etc. without requiring any special post-treatment.

[0013]

【Example】

 (Example 1)

[0014]

[Table 1]

Iron (500 kg) of the chemical composition shown in Table 1 was melted in a high-frequency induction furnace sealed with argon gas, and the melt was allowed to flow from a tundish through a nozzle at a temperature of 1620 ° C. to which an oxidation inhibitor (octadecylamine) was added. The water added while changing the addition amount of was sprayed at a high pressure of 1000 kg / cm ² to produce an iron powder. The atmosphere gas is Ar
It was used. In addition, as a comparative example, iron powder was produced under the same conditions as above using water without addition of an oxidation inhibitor. The average particle size of the iron powder obtained in these examples after classification was 9.3 to 9.8 μm, and the variation was extremely small.

[0016]

[Table 2]

Table 2 shows the relation between the amount of the oxidation inhibitor added to water and the oxygen content of the obtained iron powder.
FIG. 1 illustrates these relationships. As can be seen from these, when water containing no oxidation inhibitor of Comparative Example is used, the oxygen content of the iron powder is about 20,000 pp.
m is also included, but the addition amount of the oxidation inhibitor is 0.1%,
When increasing to 0.2%, 03%, and 0.5%, the oxygen content of the iron powder was 14630 ppm, 9740 ppm, and 3990, respectively, despite the small amount of the oxidation inhibitor added.
It decreases sharply to 1980 ppm.

Further, as the amount of the oxidation inhibitor added is increased, the oxygen content of the iron powder is slightly reduced, but its effect is diminished. Thus, it can be seen that the effect of suppressing the oxidation of the iron powder is extremely remarkable, even though the amount of the oxidation inhibitor added is small. Therefore, the iron powder produced by the present invention can be used as it is for various purposes as a product without any subsequent reduction treatment.

(Example 2)

[0020]

[Table 3]

500 kg of silicon steel having the chemical composition shown in Table 3 was melted in a high-frequency induction furnace sealed with argon gas in the same manner as in Example 1, and the melt was flowed from a tundish through a nozzle at a temperature of 1640 ° C. 1000 kg / cm ^{2 of} water added with an oxidation inhibitor (octadecylamine)
It was sprayed at high pressure to produce silicon steel powder. The atmosphere gas used was Ar. In addition, as a comparative example, silicon steel powder was produced under the same conditions as above using water without addition of an oxidation inhibitor. The average particle size of the silicon steel powder obtained in these examples after classification was 9.4 to 9.9 μm.

[0022]

[Table 4]

Table 4 shows the relation between the amount of the oxidation inhibitor added to water and the oxygen content in the obtained silicon steel powder, and FIG. 2 shows these relations. As can be seen from these, when water containing no oxidation inhibitor of Comparative Example is used, the oxygen content of the silicon steel powder is about 210.
Although it also contains 00 ppm, when the amount of oxidation inhibitor added increases to 0.1%, 0.2%, 0.3%: 0.5%, the amount of oxidation inhibitor added decreases to a small amount. Nevertheless, the oxygen content of the silicon steel powder is 16150 ppm and 1008, respectively.
It rapidly decreases to 0 ppm, 7630 ppm, and 2260 ppm.

Further, as the amount of the oxidation inhibitor added was increased, the oxygen content of the silicon steel powder was slightly reduced, but its effect was diminished. As described above, it can be seen that the effect of suppressing the oxidation of the silicon steel powder is extremely remarkable even though the amount of the oxidation inhibitor added is small. Therefore, the silicon steel powder produced by the present invention can be used as it is for various purposes as a product without any subsequent reduction treatment.

(Example 3)

[0026]

[Table 5]

500 kg of the chemical composition of SUS316L stainless steel (Mn-containing stainless steel) shown in Table 5 was melted in a high frequency induction furnace sealed with argon gas in the same manner as in Example 1, and this melt was heated at 1630 ° C. for tundish. From the above, and water to which an oxidation inhibitor (octadecylamine) was added was sprayed at a high pressure of 1000 kg / cm ² to produce SUS316L stainless steel powder. The atmosphere gas used was Ar. In addition, as a comparative example, SUS316L stainless steel powder was produced under the same conditions as above using water without addition of an oxidation inhibitor. The average particle size of the powders obtained in these examples after classification was 9.3 to 9.9 μm.

[0028]

[Table 6]

Table 6 shows the relationship between the amount of the oxidation inhibitor added to water and the oxygen content in the obtained SUS316L stainless steel powder, and FIG. 3 illustrates these relationships. As can be seen from these, when water containing no oxidation inhibitor of Comparative Example was used, SUS316
Oxygen content of L stainless steel powder is about 20000ppm
It also contains 0.1%, 0.2%,
When the addition amount was increased to 0.3% and 0.5%, the oxygen contents of the stainless steel powder were 15040 ppm and 11860 p, respectively, even though the addition amount of the oxidation inhibitor was small.
pm, 10030ppm, 6010ppm, and it decreases rapidly.

Further, even when the amount of the oxidation inhibitor added was increased, the oxygen content of the stainless steel powder was slightly reduced, but its effect was diminished. As described above, it can be seen that the effect of suppressing the oxidation of the stainless steel powder is extremely remarkable even though the amount of the oxidation inhibitor added is small. Therefore, the stainless steel powder produced by the present invention can be used as it is for various purposes as a product without any reduction treatment after that.

[0031]

INDUSTRIAL APPLICABILITY The present invention makes it extremely easy to prepare a metal or alloy which cannot be produced by the conventional water atomization method and which is easily oxidized at high temperature, by adding a small amount of an oxidation inhibitor to the water to be injected. It has made it possible to produce powders with a low oxygen content. For example, iron powder that is used in large quantities as an industrial material, silicon iron that is important as a magnetic material, and manganese-containing iron alloys cannot be used as they are because oxidation of the powder is severe when manufactured by the conventional water atomization method. could not. However, since the powder produced according to the present invention is suppressed in oxidation and has a low oxygen content, it can be used as it is for injection molding, sintering, etc. without requiring special post-treatment. Also, regarding the manufacturing equipment, since it is only necessary to add an oxidation inhibitor to the water used in the atomizing method, no special equipment is required at all, and there is an advantage that the manufacturing equipment of the conventional water atomizing method can be used as it is. .

[Brief description of drawings]

FIG. 1 is a diagram showing the relationship between the amount of an oxidation inhibitor added to water and the oxygen content of iron powder during iron powder production.

FIG. 2 is a diagram showing the relationship between the amount of an oxidation inhibitor added to water and the oxygen content of silicon steel during the production of silicon steel powder.

FIG. 3 is a diagram showing the relationship between the amount of an oxidation inhibitor added to water and the oxygen content of stainless steel during the production of stainless steel powder.

Claims (1)

[Claims] 1. When producing a metal or alloy powder by a water atomizing method, a molten metal or alloy is made to flow down from a nozzle, and atomized water added with an oxidation inhibitor is jetted at a high pressure from a jet nozzle. The method for producing metal or alloy powder according to claim 1, wherein the molten metal or alloy is powdered.