JPH01319606A - Production of alloy powder for paint - Google Patents

Abstract

PURPOSE:To industrially produce Al alloy powder for paint at a high yield by ejecting a molten Al alloy from a nozzle ejecting gases thereto to form liquid drops, and bringing the liquid drops into collision against a circular coni cal rotating body to rapidly cool and solidify the liquid drops, thereby forming amorphous alloy powder. CONSTITUTION:The melt 1 of the Al alloy is ejected from the nozzle 2 and the high-velocity gases are ejected from the many ejection ports of the atomizing nozzle 3 toward the falling melt 1 to put the melt 1 into the liquid drops 5. The liquid drops 5 collide against the surface of the circular conical (or horn- shaped) rotary cooling body 4. The alloy powder 6 consisting of the flattened- flake shape amorphous or amorphous and fine crystalline materials is thereby formed. The powder having 0.1-5mu thickness, 5-500mu minor axis and major axis and >=5 aspect ratio is fraction-collected from the solidified alloy powder 5 and is used as the powder for paint. The Al alloy powder 6 having the shape adequate as the pigment for paint is industrially obtd. at the high yield in this way.

Description

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

``Conventional technology'' Conventionally, A] Kakushu is used as a pigment in paints for purposes such as anticorrosion, aesthetics, and reflection of heat rays, and these paints are used as coatings for automobiles, tanks, steel frames, roofs, etc. . The shape of this A1 dressing powder is a flake shape with a width of 10 u, m, a length of 30 μm, and a thickness of 0.3 IJm. When this powder is mixed with resin and applied by brushing, spraying, etc., the A1 dressing powder becomes a resin. Due to the surface tension generated during curing, the material is laminated parallel to the coated surface (leaf ink phenomenon), forming a continuous film, which insulates the material from the outside air and provides corrosion resistance.

However, paints containing A1 powder may not have sufficient corrosion resistance against acids and alkalis.

Recently, A]-based amorphous alloys have been developed, and several alloys with better corrosion resistance than pure A1 have been developed. Therefore, it is expected that by pulverizing these alloys and mixing them into a paint film, even better corrosion resistance than the above-mentioned paints can be obtained.

As shown in Conventional Example 1, the powder shape of the alloy used in the paint must be in the form of flakes so that the powder is layered parallel to the coating surface when applied. However, it is actually quite difficult to produce flake-like powder of amorphous alloys.

The method for manufacturing flake powder of amorphous alloy is as follows:
A method is known in which a ribbon produced by the conventional single roll method or cavitation method is pulverized using a stamp mill or a ball mill, and a method in which a molten metal is atomized on the roll surface in the single roll method to obtain irregular Q11-shaped powder. However, the thickness of the powder obtained by these methods is usually about 5 to 30 μm, so when the powder obtained is mixed with resin and used as a paint, cracks may occur in the paint film, It could not be said that it was suitable as a powder for use.

Also, JP-A-60=252668 and JP-A-60-
No. 252669 discloses that powder alloyed in advance by a method such as atomization is dropped from above twin rolls, and as the powder falls, acetylene flame, oxygen hydrogen flame, and oxygen flame are ejected from concentrically arranged nozzles. - A method is disclosed in which a powder in the form of flakes is obtained by melting the powder using a heat source such as a propane flame, and simultaneously rolling and quenching the droplets using twin rolls. However, with this method, it was not possible to increase the amount of powder supplied, and it was not possible to industrially produce large quantities of flourwork-like powder.

``Problems to be Solved by the Invention'' The present invention has been made in view of the above-mentioned problems of the prior art. It is an object of the present invention to provide a method for manufacturing an alloy powder for paints, which allows aluminum alloy powder consisting of crystalline and fine crystalline materials to be manufactured industrially and at a high yield.

"Means for Solving the Problems" The method for producing an alloy powder for paint according to the present invention involves causing a molten aluminum alloy to flow out of a nozzle, spraying a gas onto the molten metal to generate droplets of the molten metal, and producing droplets of the molten metal. The droplets collide with the surface of an umbrella-shaped or horn-shaped rotating cooling body arranged in the direction of the droplet flow, and are rapidly solidified by colliding with the surface of an umbrella-shaped or horn-shaped rotating cooling body arranged in the direction of the droplet flow, thereby converting the amorphous or amorphous and microcrystalline materials into solids. It is characterized by obtaining an alloy powder.

In a preferred embodiment of the present invention, the coagulated powder has a thickness of 01 to 5 μm, a short axis and a long axis of 5 to 500 L.
Lm, aspect ratio (ratio of major axis to thickness) of 5 or more is separated.

Furthermore, in a preferred embodiment of the present invention A3, the aluminum alloy has the general formula A], a M b X c
(However, M is V, Cr, Mn, Fe, C:o,
N1, Cu, Zr, Ti, Mo, W, Ca, Li
, Mg, and one or more metal elements selected from Si, X is Y, La, Ce, Sm, Nd, tl
f, Nb, Ta, Mm represents one or more elements selected from [Mitsushmetal], a, one,
C is atomic% 50≦a≦95.05≦b≦35.05≦
C≦25. ) is used.

"Function" In order to obtain flaky amorphous or aluminum alloy powder consisting of amorphous and microcrystalline materials suitable for paint pigments, the present inventors sprayed a gas onto a molten alloy to form droplets. An experiment was conducted in which the droplets were collided with various rotary cooling bodies to rapidly solidify them. As a result, even when droplets are collided with the cylindrical rotating cooling body used in the conventional single-roll method, many powders with irregular thickness and irregular shapes are formed. As a result, the desired flaky powder could not be efficiently obtained. However, it has been found that when droplets of molten metal are made to collide with an umbrella- or horn-shaped rotating cooling body, thin leaf-shaped flakes of powder can be obtained with extremely high yield.

In the present invention, by using an umbrella-shaped or horn-shaped rotating cooling body, the surface of the cooling body is arranged at an angle with respect to the droplet flow direction, and when droplets collide with the inclined cooling body surface, It is thought that the droplet spreads in the direction of rotation of the cooling body and also spreads along the inclined surface, and as a result, the droplet becomes thicker (spread out and becomes a thin leaf-shaped flake-like powder).

By mixing the thus obtained flaky amorphous or aluminum alloy powder consisting of amorphous and fine crystals into a paint, a paint having excellent properties such as corrosion resistance can be obtained. That is, since it is in the form of thin flakes, the leaf ink is easily arranged in a flat manner during the drying of the coating film, and the surface to be coated is well covered with the flaky powder. As a result, a coating film is formed that can sufficiently withstand even harsh corrosive environments. Furthermore, since the flaky powder is thin, a coating film is formed that is less prone to cracking due to stress such as surface distortion.

In addition, by separating the coagulated powder into a powder with a thickness of 0.1 to 5 LLm, a short axis and a long axis of 5 to 500 μm, and an aspect ratio (ratio of major axis to thickness) of 5 or more, it is possible to make it more suitable for paint pigments. A flaky powder can be obtained.

In this case, the thickness is 0. ] If the thickness is less than um or d4, there is a problem in maintaining corrosion resistance over a long period of time, and if the thickness exceeds 5u or 5m, the smoothness of the coating film will deteriorate. If the short axis is less than 5 ILm, the powders overlap each other non-uniformly, and if the long axis exceeds 500 gm, the strength of the coating film will decrease. Leaf ink tends to occur when the aspect ratio becomes less than 5.

Furthermore, by using the aluminum alloy composition described in 1.1 above, it becomes easier to form an amorphous phase or a mixed phase of an amorphous phase and a microcrystalline phase when rapidly solidified. It can withstand many environments and has excellent corrosion resistance.

Embodiment FIG. 1 shows an example of an apparatus for carrying out the present invention. That is, a nozzle 2 is installed to flow out the molten metal 1 of the alloy melted in a crucible (not shown), and an atomization nozzle 3 is installed to blow high-pressure jet gas onto the falling molten metal 1. . The atomizing nozzle 3 is arranged, for example, in a circle so as to surround the nozzle 2, and jets high-speed gas 111 toward the flow of the molten metal 1 from a large number of jetting ports.
It is ￥ Ii. Below the nozzle 2, an umbrella-shaped rotary cooling body 4 is arranged with its axis of rotation slightly shifted in the direction of the oak from directly below the nozzle 2.

Therefore, high-pressure 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 1. The droplet 5 scatters while spreading downward,
It collides with the conical surface of the rotary cooling body 4 and is rapidly solidified, forming flattened flake-shaped alloy powder 6. In this embodiment, an umbrella-shaped rotary cooling body 4 as shown in FIG. 2 fa) is used;
It may also be a horn type as shown in the figure.

Incidentally, the pressure of the ejected dregs from the atomization nozzle 3 is preferably 40 kg/cm2 or more. Moreover, various gases such as argon, helium, nitrogen, air, or a mixed gas can be used as the injection gas. Further, the rotary cooling body 4 is cooled to at least 50° C. or lower by means such as water cooling, and has a rotational speed of 1,000 to 20,000.
It is preferable that r p m be used.

Test Example (Evaluation of Corrosion Resistance of Aluminum Alloys) The compositions are shown in Table 1.J- After vacuum melting various aluminum alloys, the pore size was 0.
Argon gas injection pressure 1.0k from 4mm quartz nozzle
g/cm", and the molten metal was made to collide with a roller rotating at a circumferential speed of 30 m/sec to obtain a thin strip. The obtained thin strip had a width of approximately 1 mm and a thickness of approximately 30 μm, and as a result of X-ray diffraction and TEM observation, it was confirmed that both were amorphous or a mixture of amorphous and fine crystals.

Regarding the obtained various ribbons, 3
After 3 hours of immersion at 0°C and 3 hours of immersion in IN-N a OH at 30°C, an 8G corrosion test 1- was performed. evaluation! ", × means Ichikawa's test, ΔC" means a change was observed on the surface, ■: no change was observed on the surface. In addition, the toughness of the obtained Meishin ribbon was evaluated based on whether or not 180" adhesive cracks were formed.The overall evaluation was based on the above corrosion resistance and toughness evaluation results: O... Corrosion resistance = r' L: Suitable as an alloy powder for coating, ×: Unsatisfactory as an alloy powder for corrosion-resistant paint.

In addition, for comparison, in addition to the thin strip mentioned in 1., commercially available AI
[4N), 2024 alloy, and Al-3i alloy were also subjected to similar test evaluations. These results are shown in Table 1.

From Table 1, it can be seen that aluminum alloy compositions No, ] to NO, ]6, which are preferred aluminum alloy compositions in the present invention, can provide sufficient corrosion resistance even when used as powder for paint.

Example (1) Preparation of alloy powder Using the apparatus shown in Figure 1, sample No. 2.5.6.9, Il, 14.1 shown in Table 1 (described later) was prepared.
Put the aluminum alloys of composition 5 into a crucible,
The mixture was melted at 0°C (each volume was 1 volume).

This molten metal 1 is dripped from the nozzle 2, and 100 kg of argon gas is applied to the dripping molten metal 1 from the spray nozzle 3.
g/cm2 pressure to form droplets 5, and before the droplets 5 solidify in the air, the roll diameter is about 200 m.
It was made to collide with a rotating f-reflection body having mφ, an angle of 90°, and a rotational speed of 720 rpm to obtain a leaf-shaped flaky alloy powder.

FIG. 3 shows a scanning electron micrograph of 90 pieces of alloy powder obtained by the above method using alloy sample No. 5.

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 01 to 5 g, which is a preferred embodiment of the present invention.
The yield of powders with a short axis of 5 m, a long axis of 5 to 500+1 m, and an aspect ratio (ratio of major axis to thickness) of 5 or more exceeded 70%.

In addition, the powder obtained using the alloy of sample No. 5 had a thickness of 0.5 to 411 m, an aspect ratio (ratio of the major axis to the thickness) of 10 to 100, and a minor axis and a major axis of 110.
-400tv (Sample No. 5-1) and one with a thickness (], less than I11 m, an aspect ratio (ratio of major axis to thickness) of 5 or more, and a minor axis and major axis 10 to 400 μm (sample No. 5) -2) and thickness 0.5~4gm,
Aspect ratio (ratio of major axis to thickness) less than 5, minor axis and major axis 5 to 18 ILm (Sample No. 9-3)
, spherical powder (sample No. 5-4), and 0 thickness
5 to 4 μm, aspect ratio (ratio of major axis to thickness) 5
Above, those whose major axis exceeds 500 μm (sample No. 5-
51 were prepared respectively.

Furthermore, for comparison, AI used in commercially available paints
, , f4N) was prepared (Sample No. 0.19+). This powder has a thickness of 0.31 r, m, an aspect ratio (ratio of major axis to thickness) of 5 or more, and a minor axis and a major axis of less than 50 μm.

(2) Preparation of paint Polyvinyl chloride resin 85Vo1% as resin binder
A paint was prepared by mixing 15V (]1% of each of the metal powders obtained above.

(3) Evaluation of paint film performance Prepare an SS41 steel plate with a thickness of 3 mm, width of 20 mm, and length of 50 mm. The film was painted by brushing so that the thickness of the film was around 11004z. After drying, the state of the coating film was observed and a corrosion resistance test was conducted. The corrosion resistance test was conducted by immersing the sample in 25° C. aqua regia and measuring the time taken for the base material to dissolve. The results are shown in Table 2 (described later).

From Table 2, sample No. 2.5-1゜5-2.5-3 containing aluminum alloy powder consisting of amorphous or mixed phase of amorphous and fine crystals obtained by the production method of the present invention.
．． 5-5.6.9.11.14.15 is the conventional A1 (
It can be seen that superior corrosion resistance can be obtained compared to sample No. 4N019 containing powder. However, when evaluating the coating state and corrosion resistance, it was found that the thickness was 0.1 to 5 um, the short axis and long axis were 5.
Sample No. 2 containing powder with a range of ~500LLm and an aspect ratio (ratio of major axis to thickness) of 5 or more
．． 5-], 6.9.11.14.15 are found to be particularly preferred.

(Hereinafter, blank space) "Effects of the Invention" As explained above, according to the present invention, molten aluminum alloy is caused to flow out from a nozzle, and droplets of the molten metal are generated by spraying gas onto the molten metal. By colliding the droplets before solidification with the surface of an umbrella-shaped or horn-shaped rotating cooling body installed in the direction of the droplet flow, the droplets are rapidly cooled and solidified, thereby producing an amorphous material having a shape suitable as a pigment for paint. Aluminum alloy powder consisting of a mixed phase of crystalline or amorphous and fine crystals 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 (ta) and (bl) show different examples of rotary cooling bodies used in the apparatus for carrying out the present invention. Figure 1 is a 90x scanning electron micrograph showing the particle structure of the amorphous alloy powder obtained in the example of the present invention. 3 is an atomization nozzle, 4
5 is a rotary cooling body, 5 is a droplet, and 6 is a flaky alloy powder.

Claims (3)

[Claims] (1) Flowing the molten aluminum alloy from the nozzle,
Droplets of the molten metal are generated by spraying gas onto the molten metal, and the droplets are made to collide with the surface of an umbrella-shaped or horn-shaped rotating cooling body arranged in the direction of the droplet flow before they solidify. A method for producing an alloy powder for paints, which comprises obtaining an amorphous or an alloy powder consisting of an amorphous and fine crystalline material by rapid solidification. (2) An alloy for coating according to claim 1, wherein from the solidified powder, an alloy having a thickness of 0.1 to 5 μm, a minor axis and a major axis of 5 to 500 μm, and an aspect ratio (ratio of major axis to thickness) of 5 or more is fractionated. Powder manufacturing method. (3) As the aluminum alloy, general formula AlaMb
Xc (where M is V, Cr, Mn, Fe, Co, Ni
, Cu, Zr, Ti, Mo, W, Ca, Li, Mg, S
one or more metal elements selected from i, X is Y
, La, Ce, Sm, Nd, Hf, Nb, Ta, Mm[
50≦a≦95, 0 in atomic%
．． 5≦b≦35, 0.5≦C≦25. 3. The method for producing an alloy powder for paint according to claim 1 or 2, using a powder having the composition shown in (1).