KR20170048438A - Metal Powder for Modeling - Google Patents

Abstract

A metal powder for molding having a total content of Ni, Fe and Co of at least 50% by mass, wherein the particles contain at least one of Ni, Fe and Co, and the number of particles having a circularity of less than 0.80 Of the total number of particles is 10% or less and the ratio P3 of the number of particles having a circularity of 0.95 or more to the total number of particles is 50% or more. These molding metal powders are excellent in various performances.

Description

{METAL POWDER FOR MODELING}

TECHNICAL FIELD The present invention relates to a molding metal powder used for a three-dimensional laminate molding method, a laser coating method, a spraying method, a deposition method and the like.

3D printers are used to produce sculptures made of metal. In this 3D printer, a molding is produced by a laminate molding method. In the multilayer forming method, the spread metal powder is irradiated with a laser beam or an electron beam. By irradiation, the metal is melted. The metal is then solidified. By such melting and solidification, the particles in the powder are bonded to each other. The irradiation is selectively performed on a part of the metal powder. The unexposed portion of the powder is not melted. The bonding layer is formed only at the portion where irradiation is performed. A beam may be irradiated to the metal powder that is sprayed from the nozzle and proceeds to obtain a bonding layer.

On the bonding layer, the metal powder is further spread. This metal powder is irradiated with a laser beam or an electron beam. By irradiation, the metal is melted. The metal is then solidified. By such melting and solidification, the particles in the powder are bonded to each other to form a new bonding layer. The new bonding layer also bonds with the existing bonding layer.

By repeating the bonding by irradiation, the aggregate of the bonding layer gradually grows. By this growth, a sculpture having a three-dimensional shape is obtained. By using the lamination molding method, a molding of a complex shape can be easily obtained.

A laser coating method is used to form the metal coating layer. In the laser coating method, a laser beam is irradiated to a metal powder spread on the base. The metal is melted by irradiation. The metal is then solidified. By such melting and solidification, the particles in the powder are bonded to each other. Particles also bind to the lower limb. Coating is formed by bonding. A beam may be irradiated to the metal powder that is sprayed from the nozzle and proceeds. A metal coating layer may be formed by a spraying method or a spraying method.

The metal powder used for the lamination molding method, the laser coating method, the spraying method, the growing method and the like is produced by the water atomization method, the gas atomization method and the like. The property of such a metal powder affects the handling property. The properties of the metal powder further affect the physical properties of the three-dimensional molding and the coating layer.

Japanese Patent Application Laid-Open No. 2001-152204 discloses a metal product in which a metal having a melting point lower than the melting point of the molding is impregnated into a molding obtained by a laminate molding method. Impregnation increases the density of metal products.

Japanese Patent Application Laid-Open No. 2006-321711 discloses a metal powder having an arithmetic average circularity of 0.7 or more. In such a powder, the surface of the particle is covered with the anti-aggregation particles. In such a powder, aggregation hardly occurs. These powders are excellent in handleability. The density of the molding obtained from such powder is large. These sculptures have excellent strength.

Japanese Patent Application Laid-Open No. 2011-21218 discloses a powder containing a laser absorbent. The sculptures obtained from these powders are excellent in strength.

Patent Document 1: JP-A-2001-152204 Patent Document 2: JP-A 2006-321711 Patent Document 3: JP-A No. 2011-21218

In recent years, the three-dimensional lamination shaping method and the laser coating method are rapidly spreading, and the required performance for powder is increasing. It is an object of the present invention to provide metal powders for molding which are excellent in performance.

According to one embodiment of the present invention, there is provided a metal powder for molding, comprising a plurality of particles, wherein the particles contain at least one of Ni, Fe and Co, and the total content of Ni, Fe and Co is 50 mass% ,

The ratio P1 of the number of particles having a circularity of less than 0.80 to the total number of particles is not more than 10%

There is provided a molding metal powder having a ratio P3 of the number of particles having a circularity of 0.95 or more to the total number of particles of 50% or more.

Such molding metal powder contains many particles having a high degree of circularity. These powders are excellent in handleability. The sculptures obtained from these powders are high strength. The coating layer obtained from such a powder is excellent in abrasion resistance.

The metal powder for molding according to the present invention is a collection of a plurality of particles. From these powders, a molding can be obtained by a laminate molding method. From these powders, a coating layer can be obtained by a laser coating method. These powders are also suitable for spraying and growing.

Each particle contains at least one of Ni, Fe and Co. The particles may contain only one of Ni, Fe and Co. The particles may contain Ni and Fe. The particles may contain Fe and Co. The particles may include Co and Ni. The particles may include Ni, Fe and Co. As the preferable material of the particles, an Fe alloy (SUS316, SUS630, etc.), a Ni alloy (ALLOYC276 equivalent, ALLOY718 equivalent or the like), a Co alloy (Stellite No.6 equivalent, Stellite No.20 equivalent or the like) is exemplified.

The total content of Ni, Fe and Co in these particles is 50 mass% or more. These powders are suitable for applications requiring high strength, high abrasion resistance or corrosion resistance. The total content rate may be 100% by mass.

The particles may contain other elements. As the other elements, at least one element selected from the group consisting of S, Mg, Al, Ti, V, Cr, Mn, Si, Cu, Zn, Ga, Ge, Zr, Nb, Mo, Hf, Ta, W, In, Sn, Pr, Nb, Gd, Tb, Dy, Yb, Y, B, P, Bi, N and C are exemplified.

In the present invention, the ratios P1, P2 and P3 are defined as follows.

P1: the ratio of the number of particles having a circularity of less than 0.80 to the total number of particles

P2: ratio of the number of particles having a circularity of 0.80 or more and less than 0.95 to the total number of particles

P3: the ratio of the number of particles having a circularity of 0.95 or more to the total number of particles

The circularity Ro is expressed by the following equation:

Ro = 4? S / L ²

. In this equation, S is the projection plane of the particle or its section, and L is the contour length of the projection. For the measurement of the projection area S and the contour length L, for example, an image analyzing apparatus is used.

In the powder according to the present invention, the ratio P1 is 10% or less. In other words, the sum of the ratio P2 and the ratio P3 exceeds 90%. Moreover, in these powders, the ratio P3 is 50% or more. The fluidity and filling properties of such powders are high. When such a powder is used in a laminate molding method or a laser coating method, it can be spread smoothly and densely. These powders are excellent in handleability. Since the powder is densely spread, the molding and the coating layer obtained from such a powder are excellent in strength.

From the viewpoints of handleability and strength, the ratio P1 is more preferably 7% or less, and particularly preferably 4% or less. Ideally, the ratio P1 is zero.

From the viewpoints of handleability and strength, the ratio P3 is more preferably 70% or more, and particularly preferably 80% or more. Ideally, the ratio P3 is 100%.

Since such a powder is densely spread, impregnation of a low melting point metal with respect to the sculpture disclosed in Japanese Patent Application Laid-Open No. 2001-152204 is unnecessary. Melting of the low melting point metal does not occur even if the molding obtained from such a powder is used under a high temperature environment. Such a molding is suitable for use in a high temperature environment. Of course, the molding material may be impregnated with a low melting point metal.

Such powder is excellent in fluidity, so that the anti-aggregation particles disclosed in JP-A-2006-321711 are unnecessary. In the powder not containing the anti-aggregation particles, such anti-aggregation particles do not inhibit binding of the particles to each other. Therefore, the molding and the coating layer obtained from such a powder are excellent in strength. Of course, such powder may contain anti-aggregation particles.

Since the molding and the coating layer obtained from these powders are excellent in strength, mixing of such a laser absorbing agent disclosed in JP-A No. 2011-21218 is unnecessary. Therefore, defects due to the laser absorbent do not occur. Of course, such a powder may be mixed with a laser absorbent.

As described above, these powders are excellent in fluidity and filling property. Such powder can be densely packed in a container or the like. Preferably, the ratio (d1 / d2) of the bulk density d1 and filling density d2 of such a powder is 0.80 or more. Such a powder has a small volume shrinkage upon melting. In the molding obtained from these powders, there are few vacancies. From these powders, a molding and a coating layer excellent in strength can be obtained. From this viewpoint, the ratio (d1 / d2) is more preferably 0.85 or more, and particularly preferably 0.90 or more. Ideally, the ratio (d1 / d2) is 1.00. By adjusting the circularity and adjusting the particle size distribution, a powder having a large ratio (d1 / d2) can be obtained.

The bulk density d1 is measured in accordance with the provisions of 'JIS Z 2504'. The filling density d2 is measured in accordance with the provisions of 'JIS Z 2512'.

Preferably, in such a powder, the following formula:

Y = (D10 x D90) / D50 ²

(D10 is cumulative 10 volume% particle diameter, D50 is cumulative 50 volume% particle diameter, and D90 is cumulative 90 volume% particle diameter).

Is not less than 0.80 and not more than 1.20.

In the measurement of the particle diameters D10, D50 and D90, the total volume of the powder becomes 100%, and the cumulative curve is obtained. The particle diameter at the point where the cumulative volume on this curve is 10% is D10. The particle diameter at the point where the cumulative volume on this curve is 50% is D50. The particle diameter at the point where the cumulative volume on this curve is 90% is D90. The particle diameters D10, D50 and D90 are measured by a laser diffraction scattering method. As a device suitable for such a measurement, a laser diffraction / scattering type particle diameter distribution measuring apparatus "Microtrack MT3000" manufactured by Nikkiso Co., Ltd. can be mentioned. In the cell of such an apparatus, the powder flows together with pure water, and the particle diameter is detected based on light scattering information of the particles. Ten measurements are made, and an average value is calculated.

Powders having a value Y of 0.80 or more and 1.20 or less have a particle size distribution close to a lognormal distribution. These powders are excellent in fluidity and filling property. Such a powder has a small volume shrinkage upon melting. In the molding obtained from such a powder, the porosity is low. From these powders, a molding and a coating layer excellent in strength can be obtained. From the viewpoint of strength, the value Y is more preferably 0.85 or more, and particularly preferably 0.90 or more. From the viewpoint of strength, the value Y is more preferably 1.15 or less, and particularly preferably 1.10 or less.

From the viewpoint that the particles are difficult to become satellites, the particle diameter D10 is preferably 1 mu m or more, more preferably 5 mu m or more, and particularly preferably 10 mu m or more.

The particle diameter D50 is preferably from 15 탆 to 50 탆, particularly preferably from 20 탆 to 30 탆 from the viewpoint of versatility as a molding and a coating layer.

Such powders can be prepared by various methods. Specific examples of the production method include a water atomization method, a gas atomization method, a plasma atomization method, a rotating electrode method, a disk atomization method, a melt spinning method, a mechanical grinding method, and a chemical reduction method. A plurality of manufacturing methods may be combined. For example, the particles obtained by the water atomization method may be mechanically pulverized. As a preferable production method, a water atomization method and a gas atomization method are exemplified.

In the water atomization method, for example, raw materials are injected into a crucible having pores at the bottom. This raw material is heated and melted in a high-frequency induction furnace in an atmosphere of air, argon gas or nitrogen gas. Water is injected into the raw material flowing out of the pores. The raw material is quenched and solidified to obtain a powder.

In the gas atomization method, for example, raw materials are injected into a crucible having pores at the bottom. This raw material is heated and melted in a high-frequency induction furnace in an atmosphere of air, argon gas or nitrogen gas. Helium gas, argon gas or nitrogen gas is injected into the raw material flowing out of the pores. The raw material is quenched and solidified to obtain a powder.

By adjusting the conditions of the atomization, a powder containing a large amount of particles with high circularity is obtained. Particles with high circularity may be selected from powders obtained by atomization. One example of the selection method is to filter by a mesh. As another means of selection, an image analysis method can be mentioned. In the image analysis method, the circularity of the particle is measured by the analyzer. Particles whose circularity falls within a predetermined range are automatically selected.

Example

Hereinafter, the effects of the present invention will be clarified by examples. However, the present invention is not limitedly interpreted based on the description of these examples.

[Preparation of alloy]

An alloy having the components shown in the following Table 1 was prepared. On the other hand, in Table 1, Bal. Means the rest.

[Experiment I Three-Dimensional Lamination Forming Method]

[Production of sculpture]

The metal powders for molding of Examples 1 to 35 and Comparative Examples 1 to 10 shown in Tables 2 and 3 were obtained from the alloys shown in Table 1. Each powder was obtained by subjecting a plurality of particles to sieving. These powders were obtained by the water atomization method, the gas atomization method or the disk atomization method.

The powder was spread and irradiated with a laser beam. By irradiation, the particles were bonded to each other to form a bonding layer. The powder was spread on the bonding layer and irradiated with a laser beam. Such spreading and irradiation were repeated to obtain a shaped product having a predetermined shape.

[Spreadability]

During the fabrication of the molding, the state of the spread powder was visually observed. The spreadability was rated according to the following criteria.

S: Very good

A: Good

B: Normal

F: Poor

The results are shown in Tables 2 and 3 below.

[Relative density]

The density of the sculpture was measured. The ratio of these densities to the true density was calculated. The results are shown in Tables 2 and 3 below.

[The tensile strength]

The tensile strength of the sculpture was measured in accordance with 'JIS Z 2550'. The ratio of the tensile strength to the tensile strength of the solvent was calculated. The results are shown in Tables 2 and 3 below.

[Overall evaluation]

The spreadability, the relative density and the tensile strength were evaluated according to the following criteria.

S: Very good

A: Good

B: Normal

F: Poor

The results are shown in Tables 2 and 3 below.

As shown in Tables 2 and 3, the powder of each example is excellent in comprehensive evaluation. From this result, the superiority of the present invention is clear.

[Experiment II Laser coating method]

[Production of coating layer]

The metal powders for molding of Examples 36 to 70 and Comparative Examples 11 to 20 shown in Tables 4 and 5 were obtained from the alloys shown in Table 1. Each powder was obtained by subjecting a plurality of particles to classification by sieving. These particles were obtained by a water atomization method, a gas atomization method or a plasma atomization method.

The powder was spread on a plate made of pure Fe and irradiated with a laser beam. By irradiation, the particles were bonded to each other to form a coating layer.

[Spreadability]

Spreadability was rated in the same manner as in Experiment I. The results are shown in Tables 4 and 5 below.

[Abrasion resistance]

The amount of wear of the cover layer was measured by an oscillation test. And the ratio of wear amount of the pure Fe-based solvent to the wear amount was calculated. The results are shown in Tables 4 and 5 below.

[Overall evaluation]

Spreadability and abrasion resistance were evaluated according to the following criteria.

S: Very good

A: Good

B: Normal

F: Poor

The results are shown in Tables 4 and 5 below.

As shown in Tables 4 and 5, the powder of each example is excellent in comprehensive evaluation. From this result, the superiority of the present invention is clear.

The powder according to the present invention is also suitable for a 3D printer of a type in which powder is ejected from a nozzle. Such a powder is also suitable for a laser coating method of a type in which powder is sprayed from a nozzle.

Claims (5)

A metal powder for molding, comprising a plurality of particles and containing at least one of Ni, Fe and Co, and a total content of Ni, Fe and Co of not less than 50 mass%
The ratio P1 of the number of particles having a circularity of less than 0.80 to the total number of particles is not more than 10%
A metal powder for molding, wherein the ratio P3 of the number of particles having a circularity of 0.95 or more to the total number of particles is 50% or more. The method according to claim 1,
Wherein the ratio P3 is 80% or more. 3. The method according to claim 1 or 2,
And a ratio (d1 / d2) of a bulk density d1 to a filling density d2 of 0.80 or more. 4. The method according to any one of claims 1 to 3,
The following formula:
Y = (D10 x D90) / D50 ²
(In the above formula, D10 is cumulative 10 volume% particle diameter, D50 is cumulative 50 volume% particle diameter, and D90 is cumulative 90 volume% particle diameter).
Is not less than 0.80 and not more than 1.20. 5. The method of claim 4,
Wherein the D10 is 1 占 퐉 or more.