JPH01287209A - Manufacture of amorphous alloy powder for corrosion resistant coating - Google Patents

Abstract

PURPOSE:To industrially manufacture amorphous alloy powder for corrosion resistant coating at high yield by atomizing gas against molten metal flow of alloy, which is capable to form the amorphous phase, developing drip, collapsing this on surface of an umbrella type rotary cooling body and rapidly cooling to solidify. CONSTITUTION:The molten metal 1 of the alloy, which is capable to form the amorphous phase, is flowed out from a nozzle 2. As the above alloy, mate rial, etc., composing of 5-12 atom % Ni, 5-25% Cr, 0,3-5.0% Mo, 8-13% P, 7-15% C and the balance Fe or 5-40% Cr, 15-25% P and the balance Ni or 40-60% (Nb, Ta) and the balance Ni, is used. By atomizing the gas against this molten metal flow from the atomizing nozzle 3, the drip 5 of the molten metal 1 is developed. This drip 5 is collapsed on the surface of the umbrella type or horn type rotary cooling body 4 until this is solidified, and rapidly cooled and solidi fied, and flasky alloy powder 6 is formed to obtain the amorphous alloy powder for the corrosion resistant coating. Further, it is desirable to use by selecting the powder having 0.5-5mum thickness, 5-500mum short diameter and long diameter and 1-10 the ratio thereof, and >=5 aspect ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial Field of Application" The present invention C" relates to a method for producing an amorphous alloy powder used as a pigment for corrosion-resistant paints.

"Prior Art" Conventionally, paints containing stainless steel powder have been commercially available as paints that require corrosion resistance. This stainless steel powder has a flake shape with a width of 11111 m, a length of H] gm, and a thickness of 0.3 trm, and when this powder is mixed with resin and applied with a brush or spray, the stainless steel powder The surface tension generated when the resin hardens causes the materials to be layered parallel to the coated surface, forming a continuous stainless steel film that insulates the material from the outside air and provides corrosion resistance.

However, stainless steel has stress corrosion cracking, pitting corrosion,
Due to drawbacks such as crevice corrosion and hydrogen embrittlement, paints containing the stainless steel powder may not provide sufficient corrosion resistance.

In recent years, alloys such as amorphous alloys that have better corrosion resistance than stainless steel have been developed, and by powdering these alloys and mixing them into paints, even better corrosion resistance can be obtained. Be expected. Examples of such attempts include JP-A No. 60-252668 and JP-A No. 6
In No. 0-252669, the length or width is vi, 1
It has been proposed to use scale-like amorphous alloy powder with a size of 0 to several 100 μm and a thickness of 5 μm or less.

As shown in the above-mentioned conventional examples, the powder used for the corrosion-resistant paint needs to be in the form of flakes so that when applied, the powder is layered parallel to the coating surface. However, it is actually quite difficult to produce flaky powder using an amorphous alloy.

A method for producing flaky powder using an amorphous alloy is to make a ribbon or strip produced by the conventional single roll method or cavitation method absorb hydrogen to make it embrittle.
A method of pulverizing with a stamp mill or a ball mill, and a method of atomizing /8 hot water on the roll surface in a single roll method to obtain irregularly shaped powder are known. However, the thickness of the powder obtained by these methods is usually 5 to 20
Since the particle size is about .mu.m, when the obtained powder is mixed with a resin and used as a paint, cracks may occur in the coating film, making it unsuitable as a powder for corrosion-resistant paints.

In addition, in the above-mentioned JP-A-60-252668 and JP-A-60-252669, powder alloyed in advance by a method such as atomization is dropped from above the twin rolls, and as the powder falls, a concentric shape is formed. The powder is melted by a heat source such as an acetylene flame, an oxygen-hydrogen flame, or an oxygen-propane flame, which is ejected from a nozzle placed in the A method of obtaining a powder is disclosed. However, in this method, the powder is melted while it is falling, so it is not possible to increase the amount of powder supplied, and it is not possible to industrially produce flaky powder in large quantities.

``Problems to be Solved by the Invention'' The present invention has been made in view of the problems of the prior art described in 2.The purpose of the present invention is to provide a flake-like amorphous alloy suitable for mixing in corrosion-resistant paints. An object of the present invention is to provide a method for producing an amorphous alloy powder for corrosion-resistant paint, which enables the powder to be produced industrially and at a high yield.

"Another means to solve the problem" The method for producing amorphous alloy powder for corrosion-resistant paint according to the present invention is as follows:
A molten metal of an alloy capable of forming an amorphous phase flows out from a nozzle, and a gas is sprayed onto the molten metal to generate droplets of the molten metal, and an umbrella-shaped or horn-shaped rotating object is placed in the direction of the droplet flow. The method is characterized in that the droplets are caused to collide with the surface of the cooling body before they solidify, thereby rapidly cooling and solidifying them.

In a preferred embodiment of the present invention, the coagulated powder has a thickness of 05 to 5 μm, a short axis and a long axis of 5 to 500 μm.
m, an aspect ratio (ratio of major axis to thickness) of 5 or more, and a ratio of minor axis to major axis of 1 to IO are fractionated.

Furthermore, in a preferred embodiment of the present invention, an alloy having the following composition is used as the alloy.

■5 to 12% Ni at atomic%. 5-25% Cr, 0.
3-50% Mo, 8-13% P, 7-15% C1
The balance consists of Fe and unavoidable impurities.

■ Consisting of 5 to 40% Cr, 15 to 25% P, balance Ni and unavoidable impurities in atomic percent ■ 40 to 611% atomic percent (Nb, Tal, balance N
In order to obtain a flake-like amorphous alloy powder suitable for corrosion-resistant paint, the present inventors formed droplets by spraying a gas onto a molten alloy. An experiment was conducted in which droplets collided with a rotating cooling body and were rapidly solidified. the result,
Even if the droplets are collided with a cylindrical rotating cooling body using the conventional single roll method, a lot of powder with uneven thickness and irregular shape is formed, which is difficult to achieve the desired purpose. It was not possible to efficiently obtain flaky powder. However, the 7 nights of Nyong Yi? It has been found that when the powder is impinged on an umbrella- or horn-shaped rotary cooling body, thin, leaf-shaped, flaky amorphous powder can be obtained at an extremely high yield.

The reason for this is not well understood, but by using an umbrella-shaped or horn-shaped rotating body, the surface of the rotating body is arranged at an angle with respect to the droplet flow direction. When it collides with the body surface, it spreads in the rotational direction of the body and also spreads along the inclined surface, and as a result, it is thought that the droplet spreads out more and becomes a thin leaf-shaped flake-like powder.

By mixing the flaky amorphous alloy powder thus obtained into a paint, a corrosion-resistant paint with excellent properties can be obtained. That is, since it is in the form of thin flakes, it is easily arranged in a flat manner during drying of the coating film, and the surface to be coated is well covered with the flaky powder of the amorphous alloy. As a result, a coating film is formed that can sufficiently withstand even harsh corrosive environments. In addition, since the thickness of the flaky powder is thin, a coating film that does not easily crack due to stress such as surface distortion is formed.

In addition, from the coagulated powder, we can separate powders with a thickness of 05 to 5 g m, a short axis and a long axis of 5 to 500 μm, an aspect ratio (ratio of the long axis to the thickness) of 5 or more, and a ratio of the short axis to the long axis of 1 to 10. (By applying v), it is possible to obtain a flake-like powder that is more suitable for i6J erodible paint. If the width exceeds li, m, the smoothness of the coating will deteriorate. If the minor axis is 5 μm, the powders will overlap unevenly, and if the major axis exceeds 500 μm, the strength of the coating will decrease. If the aspect ratio is 5 μm, the strength of the coating will decrease. If the ratio of the short axis to the long axis is less than 10 or exceeds 10, leaf ink is less likely to occur.Also, if the ratio of the short axis to the long axis exceeds 10, the flaky powders will not overlap each other sufficiently, resulting in a decrease in corrosion resistance. There is a 1tfi direction.The ratio of the short axis to the long axis is
] to 5 is more preferable.

Furthermore, by using the alloy composition described above, it is easy to form an amorphous phase when rapidly solidified, and it has excellent corrosion resistance that can withstand harsh corrosive environments.
It can be done in January.

Embodiment J FIG. 1 shows an example of an apparatus for carrying out the present invention. That is, a nozzle 2 is installed to flow out a molten alloy 1 melted in a crucible (not shown). , an atomizing nozzle 3 is installed that blows high-pressure jet gas (-1) against the falling molten metal 1.The atomizing nozzle 3 is
For example, it is a circular member surrounding the nozzle 2, and has a structure in which high-speed gas is ejected in the direction of the flow of the molten metal 1 from a large number of ejection ports. Below the nozzle 2, an umbrella-shaped rotary cooling body 4 is arranged with its rotational axis slightly shifted laterally from directly below the nozzle 2.

Therefore, high-pressure jet gas is blown from the atomizing nozzle 3 against the flow of the molten metal 1 flowing out from the nozzle 2 and falling, thereby forming droplets 5 of the molten metal I. The droplet 5 flies off while spreading downward, collides with the conical surface of the rotary cooling body 4, and cools and solidifies, forming a flattened flake-shaped alloy powder 6. In this embodiment, an umbrella-shaped cooling body 4 as shown in FIG. 2(fa) is used as the one-rotation cooling body 4;
) or a second horn type as shown in
(not shown in Figure fc); the inner periphery of the eel may be umbrella-shaped.

The injection gas pressure from the atomization nozzle 3 is preferably 40 kg/cm21u. In addition, as the injection gas, various gases such as argon, helium, nitrogen, air, or mixed gases can be used.1 Furthermore, the rotary cooling body 4 is cooled to at least 50°C or less by means such as water cooling. and the rotation speed is 1000~2
0000 rpm is preferable.

Test Example (Evaluation of Corrosion Resistance of Amorphous Alloys) After vacuum melting various alloys whose compositions are shown in Table 1, argon gas is ejected from a quartz nozzle with a hole diameter of 0.4 mm at a pressure of 1.0 kg/cm2, and the molten metal is heated at a circumferential speed. A thin ribbon was obtained by colliding with a single roll rotating at 30 m/sec. The obtained thin strip has a width of about 1 m.
m, and a thickness of approximately 30 μm, and as a result of X-ray diffraction, it was confirmed that both were amorphous single phase.

Regarding the obtained various ribbons, 30
After 24 h immersion at °C, after 24 h immersion at 30 °C in lN-H2SO4, and after 24 h immersion in lOmol-FeCl,
A corrosion test was conducted after immersion at 0°C for 1 hour.

The evaluation was based on the following criteria: ×: severe corrosion; Δ: pits observed; ○: no change observed on the surface. In addition, the toughness of the obtained various ribbons was evaluated based on whether they could be bent closely at 180°. The overall evaluation was based on the above corrosion resistance and toughness evaluation results: 0: Suitable as an alloy powder for corrosion-resistant paints, ×: Unsatisfactory as an alloy powder for corrosion-resistant paints.

1] For comparison, in addition to the amorphous alloy ribbon mentioned above, commercially available austenitic stainless steel 5US304.
A similar test evaluation was conducted for 5US316L. These results are shown in Table 1 (described below).

From Table 1, ■ Atomic % is 5-12% Ni, 5-25%
Cr, 0.3-5.0% MO18-13% P, 7
~15% C1 balance Fe and unavoidable impurities, ■ atomic %
5-40% Cr, 15-25% P, balance Ni and unavoidable impurities, ■ 40-60% (Nb, atomic%)
Samples Nos. 9, 10, 16 to 21, and 24 to 28 with compositions in the range of Tal, balance Ni, and unavoidable impurities are:
It can be seen that the alloy powder has properties suitable for use as an alloy powder for corrosion-resistant paints.

Example (1) Preparation of alloy powder Using the apparatus shown in Fig. 1, sample No. in Table 1,
9.10.17. +9.2], 24.25.26 were put into a crucible and heated at 1200°.
It was melted with C to obtain molten metal 1.

This molten metal 1 is dripped from a nozzle 2, and 100k of argon gas is applied to the dripping molten metal 1 from an atomizing nozzle 3.
A droplet 5 was formed by spraying at a pressure of g/cm2. This droplet 5 was placed on a roll with a diameter of 200 mmφ and a cone angle of 90°.
The powder was collided with a rotary cooling body having a rotational speed of 720 rpm to obtain a leaf-shaped flaky alloy powder.

FIG. 3 shows a 100x scanning electron micrograph of the alloy powder obtained by the above method using alloy sample No. 9.

The alloy powders of each composition obtained by the above method were classified, and those having the shape characteristics shown in Table 2 were separated. Note that the thickness is 05 to 5μ, which is a preferred embodiment of the present invention.
m, minor axis and major axis 5 to 500 μm, aspect ratio (ratio of major axis to thickness) 5 or more, ratio of minor axis to major axis 1 to 10
The yield of powders exceeded 70% in all cases.

In addition, the powder obtained using sample No. 9 alloy has a thickness of 1 to 4 μm, an aspect ratio (ratio of major axis to thickness) of 10 to 100, a ratio of minor axis to major axis of 1 to 5, and a minor axis of and one with a long diameter of lO ~ 400 μm (sample *4 No. 9-1
1, with a thickness of less than 0.5 μm, an aspect ratio (ratio of major axis to thickness) of 5 or more, a ratio of minor axis to major axis of 1 to 5, and a minor axis and major axis of lO to 400 um (sample No. 9-
2) and those with a thickness of 1 to 4 μm, an aspect ratio (ratio of major axis to thickness) of less than 5, a ratio of minor axis to major axis of 1 to IO1, and a major axis of 5 to 36 μm (sample No. 9-31 and 1 Spherical powder (sample No. 9-41 and thickness l −
4B m, an aspect ratio (ratio of major axis to thickness) of 5 or more, a ratio of minor axis to major axis of 1 to 5, and a major axis of over 500 gm (sample N6.9-51) were prepared.

Furthermore, for comparison, powder of stainless steel 5US304, which is used in commercially available corrosion-resistant paints, was prepared (sample No.
．． 13+. This powder has a thickness less than 05, an aspect ratio (
Ratio of major axis to thickness) 5 or more, ratio of minor axis to major axis l~l
The O1 short axis and long axis are less than 36 μm.

(2) Preparation of paint Polyvinyl acetate resin 85Vo1% as resin binder
A paint was prepared by mixing 15Vo1% of each of the metal powders obtained above.

(3) Evaluation of paint film performance SS4 steel plate with thickness 3 mm, width 20 mm, and length 50 mm was prepared, and after sandblasting, it was ultrasonically cleaned in L. The coating was applied with a brush so that the thickness of the coating film was approximately 100 gm. After drying, the state of the coating film was observed and a corrosion resistance test was conducted. Corrosion resistance test 1 was conducted by immersing the sample in 20°C aqua regia and measuring the time it took for the base metal to dissolve. The results are shown in Table 2 (described later).

From Table 2, sample No. 9-1.9-2.9-3.9- containing amorphous alloy powder obtained by the manufacturing method of the present invention
5.10.17.19.2], 24.25.26 is
Sample N containing conventional Sudenless 5US304 powder
It can be seen that superior corrosion resistance can be obtained compared to No. 0 and No. 13. However, when evaluating the coating film condition and corrosion resistance comprehensively,
Thickness 0.5 to 5 gm, short axis, 1-5. J: length 5~5
Sample No. 00 μm, an aspect ratio (ratio of major axis to thickness) of 5 or more, and a ratio of minor axis to major axis in the range of 1 to 10! i-1, 10, 17, 19, 21, 2
It can be seen that 4, 25, and 26 are particularly preferred.

(Hereinafter, blank space) "Effects of the Invention" As explained above, according to the present invention, a molten metal of an alloy capable of forming an amorphous phase is flowed out from a nozzle, and a gas is sprayed onto the molten metal. By generating droplets and colliding them with the surface of an umbrella-shaped or horn-shaped rotating cooling body disposed in the direction of the droplet flow, the droplets are rapidly cooled and solidified before they solidify, thereby forming pigments for corrosion-resistant paint. An amorphous alloy powder having a shape suitable for this purpose can be produced industrially and in high yield.

[Brief explanation of the drawing]

Fig. 1 is a schematic sectional view showing an example of an apparatus for carrying out the present invention, and Fig. 2 (fat, fb) and fcl show different examples of rotary cooling bodies used in the apparatus for carrying out the present invention. 3 are 100x scanning electron micrographs showing the particle structure of the amorphous alloy powder obtained in the example of the present invention. In the figure, 1 is a molten metal, 2 is a nozzle, 3 is an atomizing nozzle, 4 is a rotary cooling body, 5 is a droplet, and 6 is a flaky alloy powder. (”) (b)

Claims (5)

[Claims] (1) A molten metal of an alloy capable of forming an amorphous phase flows out from a nozzle, and a gas is sprayed onto the molten metal to generate droplets of the molten metal, and an umbrella-shaped or horn is placed in the direction of the flow of the droplets. 1. A method for producing an amorphous alloy powder for corrosion-resistant paint, which comprises colliding the droplets with the surface of a rotary cooling body of a mold to rapidly solidify them before they solidify. (2) From the above coagulated powder, separate powders with a thickness of 0.5 to 5 μm, a short axis and a long axis of 5 to 500 μm, an aspect ratio (ratio of major axis to thickness) of 5 or more, and a ratio of short axis to major axis of 1 to 10. 2. A method for producing an amorphous alloy powder for corrosion-resistant paint according to claim 1. (3) As the alloy, 5 to 12% Ni in atomic %, 5
~25% Cr, 0.3-5.0% Mo, 8-13%
3. The method for producing an amorphous alloy powder for corrosion-resistant paint according to claim 1, wherein the powder comprises P, 7 to 15% of C, the balance being Fe and inevitable impurities. (4) As the alloy, 5 to 40% Cr in atomic %, 1
3. The method for producing an amorphous alloy powder for corrosion-resistant paint according to claim 1, wherein the amorphous alloy powder is comprised of 5 to 25% P, the balance Ni and unavoidable impurities. (5) As the alloy, 40 to 60% (Nb
, Ta), the balance being Ni and unavoidable impurities.