WO2016021998A1

WO2016021998A1 - Metal alloy powder for 3d printer

Info

Publication number: WO2016021998A1
Application number: PCT/KR2015/008320
Authority: WO
Inventors: 김규진
Original assignee: (주)티엠
Priority date: 2014-08-07
Filing date: 2015-08-07
Publication date: 2016-02-11
Also published as: KR20160024401A

Abstract

A stainless and titanium alloy powder prepared by a complex atomizing method developed in the present invention has 1/3 or less lower oxygen content in the powder compared with a powder prepared by a conventional water atomizing method and has approximately three times higher oxygen content and 1/4 or less lower nitrogen content in the powder compared with a powder prepared by a gas atomizing method, and thus can be applied to a special use such as a 3D printer and mold injection molding (MIM) requiring a high purity of low oxygen and nitrogen contents. In addition, there is an advantage of enabling the manufacture of a powder having various shapes such as irregular, oval and spherical shapes by varying the ratio of gas and water during complex atomizing, and the manufacturing cost is low compared with a gas atomizing method.

Description

Metal Alloy Powder for 3D Printer

The present invention is a fine powder of stainless and titanium alloys applicable to special applications such as 3D printers and MIM (mold injection molding) requiring high purity by applying a complex atomizing method of water and gas, and a manufacturing method thereof. It is about.

In general, stainless steel and titanium alloy powder is produced by gas atomization and water atomization. The water injection method enables the production of ultra-fine particles in accordance with the pressure and the injection amount of water in the water injection of the molten metal, but has the disadvantage of irregular shape and high oxygen content on the powder surface. Metal alloy powder produced by this method is widely applied to the production of general automotive structural parts, the reduction heat treatment process is essential when the production parts are completed.

Therefore, the metal alloy powder prepared by the water spray method is not applicable to special applications such as 3D printer and MIM that require high purity. On the other hand, the metal alloy powder prepared by the gas injection method is prepared by applying molten metal as a pulverization and cooling medium using inert nitrogen gas mainly as a spraying material, and oxygen content on the surface of the manufactured stainless steel and titanium alloy powder is large. While reduced, on the other hand, there is a disadvantage in that the nitrogen content in the powder is excessively high.

In addition, the powder shape is mainly made of a spherical powder as the cooling rate is slower than water. The disadvantage of this method is that the manufacturing cost is higher than the moisture content due to the use of a large amount of gas in the manufacturing process, and the nitrogen content in the powder is so high that the mechanical and physical properties required for the final product may not be realized. There is this.

The present invention was devised to solve the above problems, and an object of the present invention is to provide a fine powder of stainless and titanium alloy and a method for producing the same, which can vary the powder shape and lower the oxygen content as much as possible. .

By using the manufacturing technique used in the present invention, it is possible to produce various kinds of stainless steel and titanium powder with low oxygen content, and the oxygen content in the metal powder produced by the present invention was 1,000 ppm or less, which is compared with the water spray method. It is an object of the present invention to provide a stainless and titanium alloy powder and a method for producing the same, which can be significantly reduced to less than 1/3.

In addition, the nitrogen content in the powder is less than 1,500ppm, stainless and titanium alloy powder that can be reduced to 1/3 or less than the same composition of stainless and titanium alloy powder prepared by the conventional gas injection method and a method for producing the same It aims to provide.

The present invention is to produce a composite nozzle capable of simultaneously injecting gas and water in order to lower the oxygen content on the surface of stainless and titanium alloy powder, oxygen content on the surface of the metal powder less than 1,000ppm by changing the gas and water content and pressure The nitrogen content is less than 1,500ppm, while the powder shape has been invented a manufacturing technology that can change from spherical to elliptical.

The application of the composite water and gas injection method of the present invention enables the production of spherical stainless steel and titanium powder, which was not manufactured by the conventional water spraying method, and also has an oxygen content of more than 1/4 compared to the water spraying method. It can be applied to special purposes such as 3D printer and MIM.

In addition, the oxygen content is about 2.5 times higher than the gas injection method using gas alone, but the nitrogen content is lowered to less than 1/4, so it may be considered to be used in new fields. It can solve the problem, and also increase the manufacturing price competitiveness compared to the gas injection method.

This composite spray method is applicable to the production of metal powders, such as iron, nickel, cobalt, as well as the production of stainless and titanium alloy powder.

Figure 1. Schematic diagram of the composite spray nozzle device

Figure 2. Changes in the microstructure of the powder according to the composition ratio of the injection amount (liter / min) of water and gas during the composite injection

The schematic diagram of the composite injection nozzle apparatus used for this invention is shown in FIG. Briefly describing the preparation of the powder, according to the tundish 1, the molten metal dissolved in the air atmosphere is dropped into the nozzle body 2 having a nozzle diameter of 50 mm through a nozzle having a diameter of 6-10 mm at the bottom of the tundish. The water and gas are sprayed through the high pressure water nozzle 3 and the gas nozzle 4 in the atomizer nozzle body, and the molten metal is pulverized and quenched into fine particles to fall into the inside of the atomizer main body 5. After filtering, drying, fine stainless powder is produced.

The shape of the powder is determined by the pressure and the discharge rate ratio of water and gas. In order to manufacture spherical powder in the elliptical shape, the composition ratio of water injection amount (liter / min) and gas injection amount (liter / min) is 1 / 20-1. The range of / 100 is suitable, and the composition ratio of gas pressure (kg / cm 2) and water pressure (kg / cm ² ) is appropriately in the range of 1 / 2-1 / 100.

When the injection ratio of water and gas is 1/20 or more, the oxygen content in the powder is rapidly increased and the shape of the powder becomes irregular. When it is higher than 1/100, the nitrogen content in the powder is sharply increased, and the gas cost at the time of powder production is high.

In the above production method, the water pressure is 50-300bar is suitable, below 50bar, the average particle diameter of the powder is difficult to produce less than 100㎛, when it is higher than 300bar, the influence of water is too much greater than gas to produce irregular powder do. In addition, the amount of water discharged at the time of water injection is suitable at 50-500liter / min. If it is less than 50liter / min, the cooling rate is slowed at the time of injection, and the oxygen content on the surface of the powder is rapidly increased. If it is more than 500liter / min, the cooling rate of the powder is so fast that the powder detective becomes irregular.

The pressure of the gas is about 10-50bar, and under 10bar, the influence of the gas is so small that the powder becomes irregular, and when the pressure is higher than 50bar, the device cost of the high pressure gas is rapidly increased, and the gas consumption is too large, resulting in economical efficiency. Falls.

Hereinafter, embodiments of the present invention will be described in detail.

(Example 1)

After dissolving 400 kg by high frequency melting to obtain a typical Fe _67.5 Cr ₁₇ Ni _13.5 Mo ₂ alloy composition (wt%) of the ST316L composition, the molten metal was continuously dropped on the atomizer nozzle through a 6 mm diameter tundish nozzle.

At this time, the composition ratio of the injection amount of water and nitrogen gas in the atomizer main body was 1/80, respectively, and the water and gas pressure were 200 bar and 25 bar, respectively. The mixed solution which fell into the atomizer main body was filtered and dried in 150 degreeC atmosphere. Various properties of the powder prepared according to Example 1 are shown in Table 1, and the tissue photograph is shown in FIG.

The average particle diameter of the prepared powder was measured by a particle size analyzer, the shape and structure of the powder were investigated by scanning electron microscopy (SEM), the aspect ratio was the length and width of the powder shown in the SEM image The apparent density was measured by the apparent density meter for the powder passed through 200 mesh, the oxygen and nitrogen content in the powder was measured by an oxygen / hydrogen / nitrogen analyzer.

(Example 2)

It carried out similarly to Example 1 except having set the composition ratio of the injection amount of water and nitrogen gas to 1/60, 1/40, 1/20, respectively. The properties of the powder prepared according to Example 2 are shown in Table 1, and the tissue photograph is shown in FIG.

(Example 3)

The same procedure as in Example 1 was conducted except that 400 kg was dissolved by high frequency dissolution to obtain a typical Fe ₇₁ Cr ₁₉ Ni ₁₀ alloy composition (wt%) of the ST304L composition. The properties of the powder prepared according to Example 3 are shown in Table 1.

(Example 4)

It carried out similarly to Example 1 except having set the water pressure of Example 1 to 50 and 300 bar, respectively. Table 1 shows the properties of the powder prepared according to Example 4.

(Example 5)

It carried out similarly to Example 1 except having set the pressure of the gas of Example 1 to 10 bar, respectively. Table 1 shows the properties of the powder prepared according to Example 5.

(Example 6)

An ingot of Ti ₉₀ Al ₆ V ₄ alloy composition (wt%), which is a typical composition of titanium alloy, was carried out in the same manner as in Example 1 except that 400 kg was dissolved by high frequency dissolution. Table 1 shows the properties of the powder prepared according to Example 6.

(Comparative Example 1)

Only water was used for atomizing and the water pressure was 300 bar, in the same manner as in Example 1. Table 1 shows the properties of the powder prepared according to Comparative Example 1.

(Comparative Example 2)

Except that a soluble material using the alloy V ₄ Ti ₉₀ Al ₆ to re-dissolution was performed in the same manner as in Comparative Example 1. Table 1 shows the properties of the powder prepared according to Comparative Example 2.

(Comparative Example 3)

At the time of atomizing, only nitrogen gas was used, and the gas pressure was 30 bar in the same manner as in Example 1. Table 1 shows the properties of the powder prepared according to Comparative Example 3.

(Comparative Example 4)

Except that a soluble material using a Ti ₉₀ Al ₆ V ₄ as a dissolved material alloy was performed in the same manner as in Comparative Example 3. Table 1 shows the properties of the powder prepared according to Comparative Example 4.

(Comparative Example 5)

It carried out similarly to Example 1 except having set the injection ratio of water and gas to 1/10. Table 1 shows the properties of the powder prepared according to Comparative Example 5.

(Comparative Example 6)

The pressure of the gas was carried out in the same manner as in Example 1 except that the pressure was 5 bar. Table 1 shows the properties of the powder prepared according to Comparative Example 6.

In Fig. 2, (a) 1/10, (b) 1/20, (c) 1/40, (d) 1/80, respectively, are fine powders according to the composition ratio of the injection amount (liter / min) of water and gas. A diagram showing tissue change.

Table 1

Condition number	Alloy	Water / gas injection ratio	Injection pressure (bar)		Powder shape	Aspect Ratio (%)	Average particle size (㎛)	Apparent density (g / cm ³ )	Oxygen and Nitrogen Content (ppm)
Condition number	Alloy	Water / gas injection ratio	water	gas	Powder shape	Aspect Ratio (%)	Average particle size (㎛)	Apparent density (g / cm ³ )	Oxygen	nitrogen
Example 1	STS316L	1/80	200	25	rectangle	92-100	45	4.0	753	1,397
Example 2	STS316L	1/60	200	25	rectangle	82-93	39	3.9	905	1,311
		1/40	200	25	Spherical + oval	70-85	37	3.7	1107	1,248
		1/20	200	25	Oval	30-50	30	3.5	1,350	1,195
Example 3	STS304L	1/80	200	25	rectangle	94-100	38	3.9	847	1,365
Example 4	STS316L	1/80	50	25	rectangle	95-105	98	3.5	672	1,250
Example 4	STS316L	1/80	300	25	Oval + Irregular	20-30	16	3.3	648	1,105
Example 5	STS316L	1/80	200	10	Oval + Irregular	20-30	55	2.7	784	1,180
Example 6	Ti-6Al-4V	1/80	200	25	rectangle	92-100	35	2.3	654	1,235
Comparative Example 1	STS316L	100/0	300	-	irregular	-	23	2.7	3,003	1,168
Comparative Example 2	Ti-6Al-4V	100/0	300	-	irregular	-	19	1.6	2,355	1,246
Comparative Example 3	STS316L	0/100	-	30	rectangle	95-100	170	4.0	206	4,449
Comparative Example 4	Ti-6Al-4V	0/100	-	30	rectangle	95-100	165	2.4	157	3,743
Comparative Example 5	STS316L	1/10	200	25	irregular	-	74	2.8	1,453	1,225
Comparative Example 6	STS316L	1/80	200	5	irregular	-	86	2.8	1,355	1,345

Here, as shown in the embodiment of Table 1 and Figure 2, when manufacturing the spherical powder by the composite injection method of water and gas, the composition ratio of the injection amount (liter / min) of water and gas is 1/40-1/80 The composition ratio of gas and water pressure (kg / cm ² ) shall be at least 1/2.

On the other hand, in the case of elliptical powder production by the composite injection method of water and gas, the composition ratio of water and gas injection amount (liter / min) should be in the range of 1/20 to 1/40, and the pressure of gas and water (kg / The composition ratio for cm ² ) shall not be less than 1/2.

Oxygen content shown in the various examples is significantly lower than the oxygen content to 1/4 or more, compared to the powder prepared by using the water sand alone (Comparative Example 1), the nitrogen content is showing a similar level. In addition, although the oxygen content is about 2.5 times higher than that of powders prepared using gas injection alone (Comparative Example 2), it can be seen that the nitrogen content is significantly lower than 1/3.

It is possible to manufacture spherical stainless steel and titanium powder in the elliptical shape which was not manufactured by the conventional water spraying method by applying the composite spraying method of water and gas of the present invention, and the composite spraying method of the present invention is made of stainless and titanium alloy powder. It can be applied to the production of metal powders such as iron, nickel, and cobalt, as well as to the production of 3D printers and MIM (mold injection molding) requiring high purity with low oxygen and nitrogen content. It is possible.

(Explanation of reference numerals)

1. tundish, 2. spray nozzle body,

3. Water spray nozzle, 4. Gas nozzle,

5. Atomizer Body

ppm: one millionth of a solution's concentration unit

bar: unit of pressure

Claims

The powder is made from oval to spherical shape by applying the composite injection method of water and inert gas, and the powder of stainless and titanium alloys with an average particle diameter of 100㎛ or less
The method of claim 1, wherein the oxygen content in the prepared stainless and titanium alloy powder is 1,000 ppm or less, and the nitrogen content is 1,500 ppm or less.
The method according to claim 1, wherein the application conditions of the composite injection method is that the composition ratio of the injection amount (liter / min) and pressure (kg / cm 2 ) of water and gas is 1/20-1/8 and 1 / 2-1 / 100, respectively The pressure of the water and gas is 50-300bar and 10-50bar, characterized in that the production method of stainless and titanium alloy powder