KR20160024401A - Metal alloy powders for 3d-printer - Google Patents

Abstract

In a stainless and titanium alloy powder manufactured by complex atomizing in accordance with the present invention, the content of oxygen in the powder is lower by 1/3 or less than that of powder manufactured by an existing water injection method; and the content of oxygen is higher, about three times, than that of powder manufactured by gas injection while the content of nitrogen is lower by 1/4 or less. Accordingly, the powder is able to be applied to special purposes of a three-dimensional printer and a mold injection molding (MIM) requiring high purity with low contents of oxygen and nitrogen. In addition, an advantage of possibly manufacturing various metal alloy powders with various shapes such as an elliptical shape, circular shape, and irregular shape by varying the ratio of gas and water at the time of complex injection is achieved, and the manufacturing costs is lower than that of using with a gas injection.

Description

METAL ALLOY POWDERS FOR 3D PRINTERS

The present invention relates to a particulate stainless steel and titanium alloy powder applicable to special applications such as a 3D printer and a MIM (mold injection molding) requiring high purity by applying a complex atomizing method of water and gas, and a method of manufacturing the same .

In general, stainless steel and titanium alloy powders are produced by a gas atomizing method and a water atomizing method. The water dispersion method has a disadvantage in that it can produce ultrafine particles according to the pressure of water and the amount of injected water at the time of taking off the water, but the shape is irregular and the oxygen content is high on the surface of the powder. The metal alloy powder produced by this method is widely applied to general automobile structural parts manufacturing, and a reduction heat treatment process is essential at the completion of manufacturing parts. Therefore, it is impossible to apply the metal alloy powder produced by the water dispersion method for special purpose such as 3D printer and MIM which require high purity. On the other hand, the metal alloy powder produced by the gas spraying method is manufactured by applying the inert gas as the pulverizing and cooling medium mainly using the inert gas as the injection material, and the oxygen content on the surface of the produced stainless steel and titanium alloy powder is It is disadvantageous in that the nitrogen content in the powder is excessively increased. In addition, as the cooling rate of the powder is slower than that of water, spherical powder is mainly produced. The disadvantage of this method is that the use of a large amount of gas at the time of manufacture leads to a higher production cost than the water-dispersion method, and the nitrogen content in the powder is so high that the mechanical and physical properties required by the final product may not be realized have.

Accordingly, it is an object of the present invention to provide fine-grained stainless steel and titanium alloy powders capable of solving the disadvantages of the above-described invention and capable of diversifying the powder shape and minimizing the oxygen content, and a method of manufacturing the same.

  In order to lower the oxygen content on the surface of the stainless steel and titanium alloy powder, a composite nozzle capable of simultaneously spraying gas and water is manufactured. By changing the content and pressure of gas and water, the oxygen content of the metal powder surface is 1,000 ppm or less , A nitrogen content of less than 1,500 ppm, and a powder shape of spherical to elliptical shape.

   By applying the manufacturing technique used in the present invention, various kinds of stainless steel and titanium powder having a low oxygen content can be produced, and the oxygen content is drastically reduced to 1/3 or less as compared with the water sand method. Also, the nitrogen content in the powder was lower than 1/3 of that of the stainless steel and titanium alloy powder of the same composition prepared by the conventional gas spraying method.

  The composite spray nozzle apparatus used in the present invention is shown in FIG. The molten metal dissolved in the atmospheric air is introduced into the tundish 1 through the nozzle having a diameter of 6-10 mm at the lower end of the tundish to the nozzle body 2 having the nozzle diameter of 50 mm , Which is sprayed with water and gas through the high-pressure water nozzle 3 and the gas nozzle 4 in the atomizer nozzle main body, respectively, so that the molten metal is pulverized and quenched into fine particles to fall inside the atomizer main body 5 , Filtered and dried to produce a fine-grained stainless steel powder. The shape of the powder is determined by the pressure and discharge ratio of water and gas. In order to produce spherical powder in elliptical shape, the ratio of water injection amount (liter / min) and gas injection amount (liter / min) 100, and the ratio of the gas pressure (kg / cm 2) to the water pressure (kg / cm 2) is preferably in the range of 1 / 2-1 / 100. When the injection ratio of water to gas is 1/20 or more, the oxygen content rapidly increases in the produced powder and the shape of the powder becomes irregular. When it is higher than 1/100, the nitrogen content in the powder is drastically increased, and the gas cost is increased in the production of the powder.

In the above production method, the pressure of water is suitably in the range of 50-300 bar, the average particle diameter of the powder is less than 100 탆 at a pressure of 50 bar or less, and when the pressure is higher than 300 bar, the influence of water is much greater than the gas, do. When the water is sprayed, the discharge amount of water is 50-500 liters / min. When it is less than 50 liter / min, the cooling rate slows down at the time of spraying, and the oxygen content rapidly increases at the surface of the powder. When it exceeds 500 liter / min, the cooling rate of the powder becomes too fast. The pressure of the gas is suitably in the range of 10 to 50 bar, and when the pressure is less than 10 bar, the influence of the gas is too small to make the powder shape irregular. When the pressure is higher than 50 bar, the cost of the high-pressure gas device sharply increases and the gas consumption becomes too large. Falls.

    By applying the combined spraying method of water and gas according to the present invention, spherical stainless steel and titanium powder can be produced which can not be produced by the conventional waterproofing method, and the oxygen content is 1/4 or more It can be applied to special applications such as 3D printer and MIM. In addition, the oxygen content is about 2.5 times higher than the gas spraying method using gas alone, but the nitrogen content is relatively lowered to 1/4 or less, so it is considered that the use of the new field can be considered. Control can be solved, and the manufacturing cost competitiveness can be enhanced as compared with the gas injection method.

The complex spraying method invented by the present invention can be applied not only to the production of stainless steel and titanium alloy powder but also to the production of other metal powders such as iron, nickel, cobalt and the like.

1 is a schematic view of a composite nozzle device
(1) Tundish, (2) Injection nozzle body, (3) Water injection nozzle, (4) Gas nozzle, (5) Atomizer main body In figure 2, Microstructural change of powder according to composition ratio
(a) 1/10, (b) 1/20, (c) 1/40, (d) 1/80

(Example 1)

Representative of Fe ₆₇ Cr ₁₇ Ni ₁₃ ST316L composition _{.5 .5 2} Mo alloy composition obtained by dissolving a 400kg by a high-frequency melting to be (% by weight), and then, the molten metal becomes ATO Mai through a tundish nozzle having a diameter of 6mm to successive upper nozzles . At this time, the composition ratio of water and nitrogen gas in the atomizer body was 1/80, respectively, and the water and gas pressures were 200 bar and 25 bar, respectively. The mixed solution, which fell into the inside of the atomizer, was filtered and dried under atmospheric conditions at 150 ° C. The properties of the powders produced are shown in Table 1, and the photographs of the tissues are shown in FIG. The average particle size of the powders prepared herein was measured by a particle size analyzer. The shape and texture of the powders were examined by scanning electron microscope (SEM), and the aspect ratio was determined by measuring the length and length of the powder The apparent density of the powders having passed through 200 mesh was measured by an apparent density meter. The oxygen and nitrogen contents in the powders were measured using an oxygen / hydrogen / nitrogen analyzer.

(Example 2)

The same procedure as in Example 1 was carried out except that the composition ratios of the amounts of water and nitrogen gas injected were 1/60, 1/40, and 1/20, respectively. The properties of the powder thus prepared are shown in Table 1, and a photograph of the structure is shown in FIG. 2.

(Example 3)

Representative Fe ₇₁ Cr ₁₉ Ni _{10 <} RTI ID = 0.0 _> Except that 400 kg was dissolved by high-frequency melting so as to have an alloy composition (wt%). Table 1 shows the properties of the powders produced.

(Example 4)

The procedure of Example 1 was repeated except that the water pressure of Example 1 was 50 and 300 bar, respectively. Table 1 shows the properties of the powders produced.

(Example 5)

The procedure of Example 1 was repeated except that the pressure of the gas of Example 1 was 10 bar. Table 1 shows the properties of the powders produced.

(Example 6)

Ti ₉₀ Al ₆ V ₄ , which is a typical composition of the titanium alloy The same procedure as in Example 1 was carried out except that 400 kg of the phosphorus composition (wt%) was dissolved by high frequency dissolution. Table 1 shows the properties of the powders produced.

(Comparative Example 1)

The procedure of Example 1 was repeated except that only water was used at the time of atomization and the water pressure at this time was 300 bar. Table 1 shows the properties of the powders produced.

(Comparative Example 2)

As a dissolving material, Ti ₉₀ Al ₆ V ₄ Alloy was used as a dissolving material. Table 1 shows the properties of the powders produced.

(Comparative Example 3)

The procedure of Example 1 was repeated except that only nitrogen gas was used for atomization and the gas pressure at this time was 30 bar. Table 1 shows the properties of the powders produced.

(Comparative Example 4)

As a dissolving material, Ti ₉₀ Al ₆ V ₄ Alloy was used as a dissolution material. Table 1 shows the properties of the powders produced.

(Comparative Example 5)

The same procedure as in Example 1 was carried out except that the injection ratio of water to gas was 1/10. Table 1 shows the properties of the powders produced.

(Comparative Example 6)

The same procedure as in Example 1 was carried out except that the gas pressure was 5 bar.

Table 1 shows the properties of the powders produced.

Condition
number Alloy system Water / gas
Injection amount ratio Injection pressure
(bar) powder
shape Aspect Ratio (%) Average particle diameter
() surface
density
(g / cm ³⁾ Oxygen and nitrogen content (ppm) water gas 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 1,250 300 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

As shown in the examples of Table 1 and FIG. 2, when the spherical powder is produced by the combined spraying method of water and gas, the composition ratio of water and gas injection amount (liter / min) is 1/40 - 80, and the composition ratio for gas and water pressure (kg / cm ² ) shall be not less than 1/2.

On the other hand, when making elliptical powder by the combined injection method of water and gas, the composition ratio of water and gas injection (liter / min) should be in the range of 1/20 - 1/40, and the pressure of gas and water (kg / cm ² ) should be at least 1/2. The oxygen content shown in the examples was remarkably lowered to 1/4 or more, and the nitrogen content was comparable to that obtained when the powders were prepared by using water alone (Comparative Example 1). Further, it can be seen that the oxygen content is about 2.5 times higher than that in the case of using the gas injection alone to prepare the powder (Comparative Example 2), but the nitrogen content is remarkably low to 1/3 or less.

ppm: the concentration of the solution in units of one millionth
bar: unit of barometric pressure

Claims (3)

A powder of stainless steel and titanium alloy powder having an average particle diameter of 100 탆 or less is produced by applying the composite spraying method of water and an inert gas in the shape of ellipse to spherical powder
The method for producing a stainless steel and titanium alloy powder according to claim 1, wherein the produced stainless steel and titanium alloy powder have an oxygen content of 1,000 ppm or less and a nitrogen content of 1,500 ppm or less
The method of claim 1, wherein the composition ratio of water / gas injection (liter / min) and pressure (kg / cm ² ) is 1/20 - 1/8 and 1 / 2-1 / 100, and the pressures of water and gas are 50-300 bar and 10-50 bar, respectively, and the production method of stainless and titanium alloy powder

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