JPS5867805A - Preparation of powder - Google Patents

Abstract

PURPOSE:To simply obtain a metal powder suitable for powder metallurgy, by a method wherein a liquid cooling medium is flowed on the surface of a rotor and a molten metal is atomized while being flowed onto the cooling medium to prevent the deposition of the metal to the surface of the rotor. CONSTITUTION:The interior of a container is held under a non-oxidative atmosphere or a reductive atmosphere and a rotor 5 is rotated at a high speed. A liquid cooling medium 8 is flowed on the rotor 5 from a cooling medium supply pipe 7 and a slide nozzle 4 is opened to flow the molten metal 3 in a crucible on the cooling medium. This molten metal 3 is flowed on the rotor 5 along the liquid cooling medium while exerted by the centrifugal force by the rotor 5 and scattered and atomized by impact force to the rotor 5, the centrifugal force received from the rotor 5 and intumescent force of the cooling medium. At the same time, atomized particles are rapidly solidified from the surfaces thereof by the evaporation heat of the cooling medium 8 and solidified while an irregular shape during scattering remains to fall into a powder container 9.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method for producing powder by pouring molten metal onto the surface of a rotating body and atomizing it.

Centrifugal spraying is one of the methods for producing metal powder. This centrifugal I! The Jm method differs from the conventionally widely used molten metal atomization method in which a high-speed fluid is used to atomize the molten metal in a bath.The Jm method uses molten metal to flow onto the surface of a rotating body and atomizes the molten metal by mechanical impact force, centrifugal force, etc. This is a method of scattering and atomizing molten metal, and its mechanism is disclosed in, for example, Japanese Patent Publication No. 35-6527 and Japanese Patent Publication No. 51-47564. Due to its mechanism, this centrifugal atomization method has the advantage that it is easy to avoid contamination of the powder produced, is relatively simple in terms of packaging, and requires relatively little atomization energy. On the other hand, since the molten metal comes into direct contact with the rotating body, there is a problem that the metal may adhere to the rotating body surface or damage the rotating body surface. For this reason,
The reality is that it is particularly difficult to apply to the spraying of high melting point metals. Furthermore, since the cooling rate is limited, the resulting powder has a nearly spherical shape, which is not necessarily sufficient for use in powder metallurgy.

This invention was made in order to solve the above-mentioned conventional problems, and when molten metal is poured onto the surface of the rotating body and atomized, it prevents gold drop from adhering to the surface of the rotating body, and speeds up the cooling rate. It is an object of the present invention to provide a powder manufacturing method that allows adjustment of , and obtains a metal powder suitable for powder metallurgy.

That is, the present invention relates to a method for atomizing powder by pouring molten metal onto the surface of a rotating body and atomizing the molten metal by impact force, centrifugal force, etc. generated at that time. A liquid cooling medium is flowed on the surface of the rotating body, and molten metal is poured onto the liquid cooling medium flowing on the surface of the rotating body to atomize it, thereby producing powder metal.

Below, the secrets of this invention will be further explained based on the drawings.
This will be explained in ii11.

, a'y 1 iJ is a structure of the powder manufacturing apparatus et according to this invention↓tall',s: , In the folded explanatory diagram schematically shown, 1 is a container, and 2 is a VC installed in the container 1. 6 is a melting metal housed in the crucible 2; 4 is a slide nozzle for opening and closing the bottom opening 3a of the crucible 2; 5 is a melting metal; 1rtt is installed below, / is a rotating body, 6 is rotation + Il + 6a'
! A motor for rotating the rotary body 5 through il; 7 a cooling medium supply pipe for supplying a liquid cooling medium 8 to the rotary body 5;
9 is powder storage W +i', y. ``Also, Crucible 2
The positional relationship between the rotating body 5, the cooling medium 1d, and the supply pipe 7 is as follows:
As shown in the figure, the center M of the liquid cooling medium 8 supplied from the cooling medium supply bone 7 is located at a position slightly apart from the rotation center C of the rotating body 5, and the melting medium supplied from the crucible 2 is The center N of the metal 6 is positioned above the liquid cooling medium 8 flowing through the rotor table 1 button.

Therefore, when producing powder using such an apparatus, for example, the inside of the container 1 is replaced with an inert gas or a reducing gas to create a non-oxidizing or reducing atmosphere inside the crucible 2, and the inside of the crucible 2 is made into a non-oxidizing or reducing atmosphere. is operated to rotate the rotating body 5 at high speed. Next, liquid cooling medium 8 is flowed onto rotating body 5 from cooling medium supply pipe 7 . Then, this liquid cooling medium 8 flows on the surface of the rotating body, drawing a trajectory as shown in FIG. 2 due to centrifugal force. In this state, when the slide nozzle 4 is opened and the molten metal 6 flows, the molten metal 6 flows down onto the liquid cooling medium a flowing on the surface of the rotating body, and the molten metal 6 is subjected to centrifugal force by the rotating body 5. The liquid coolant 8 flows over the rotating body 5 along with the liquid cooling medium 8, drawing a trajectory as shown in FIG.
During this time, the molten metal 6 is dispersed and magnetized by the impact force on the rotating body 5, the centrifugal force received from the rotating body 5, and the bubble boiling force of the liquid cooling medium 8, and at the same time, it becomes foggy due to the large heat of vaporization of the liquid cooling medium 8. The particles rapidly solidify from the surface, solidify with the irregular shape left during flight, and fall into the valley 9 where no powder is stored.

The material of the rotating body 5 is preferably one with high heat resistance, but if the amount of molten metal 6 flowing down is large, it may be made of a metal material in consideration of impact resistance and thermal shock resistance. Further, as shown in FIG. 3, the rotating body 5 is divided into a molten metal receiving part 51 and a rotating shaft mounting part 52, and these parts are connected to each other by a stopper 5 at a predetermined interval.
5, and a heat insulating material 54 is arranged between them,
It is also possible to adopt a structure in which the heat in the melting area 3 is not directly transmitted to the rotating shaft 6a.

Furthermore, the shape of the rotating body 5 is not limited to a conical shape as shown in the illustrated example, but may be a flat plate shape. In addition, as the liquid cooling medium, liquefied Ar, H.

An inert or non-oxidizing material such as N2 can be used.

When the metal powder is manufactured in this way, (1) a gas film is formed on the surface of the rotating body 50 through which the liquid cooling medium 8 flows, so that the rotating body 5 is cooled well, and the thickness of the gas film is reduced; By adjusting tX, it is possible to further prevent the molten metal 3 from adhering to the rotating body 5 and damaging and breaking the rotating body 5.

■ Due to the impact force on the molten metal 60 rotating body 5, the centrifugal force from the rotating body 5, and the bubbling force of the liquid cooling medium 8, etc.
The molten metal 6 is atomized more strongly and effectively,
50 molten metal without excessively increasing the rotation speed of the rotating body
i3 can be atomized well.

■ Due to large heat absorption due to vaporization of liquid cooling medium 8,
Since the molten metal 6 collides with the rotating body 5 and is atomized by centrifugal force and immediately solidifies, the irregular shape of the powder is maintained and a powder particularly suitable for powder metallurgy is obtained.

Rapid solidification of the surface can minimize contamination even in the case of active metals or alloys containing active metals.

■ Lower part 1a of the liquid cooling medium 8 flowing onto the surface of the rotating body 50
Even when the liquid cooling medium 8 is shifted from the center of rotation of the rotating body 5 so that the trajectory of the liquid cooling medium 8 is formed in a part of the rotating body 5, the molten metal 6 can be atomized well.
The amount of liquid cooling medium 8 used can be significantly reduced.

■ By flowing the liquid cooling medium 8 toward the surface of the rotating body 50, the adhesion of the cooling medium 8 to the surface of the rotating body can be made good, and the molten metal 6 can be stably atomized. become able to.

It has advantages such as:

Next, an example will be described.

Example 1 In the apparatus shown in Fig. 1, after replacing the inside of the container 1 with argon gas, the IN melted by plasma arc melting
100 equivalent material (0.06 inch C1 sail 10 inch Si, 0.06 inch C1 sail 10 inch Si, 0.
02 To Mn, 0.003% P, 0.
002*S.

3, l-Mo, 5.5chi AZ-18-I To
Cot 4-0 Chi Tl.

0.7% V, balance Ni) molten metal 3'1150
Pour hot water into crucible 2 at 0℃. Further, a conical rotating body 5 (apex angle of 120°) with a radius of 10 cIn was rotated at high speed.

At this time, the rotational speed of the rotating body 50 can be increased from 1000 to 15000 by adjusting the amount of air to the air motor 6.
Make sure to change the rpm range. Next, at a position 1.7 crs in the radial direction from the center of rotation of the rotating body 50, liquefied argon 8 having a diameter of 3 mm was allowed to flow down from the cooling medium supply pipe 7 at a rate of 1@/l@a. Next, on the trajectory of the liquefied argon 8,
The molten metal 6 in the crucible 2 was allowed to fall naturally from a height of 10 mm. The flow rate at this time is approximately 4 kg/
spraying was performed for about 1 minute. Thereafter, the obtained powder was examined and the results shown in Table 1 were obtained.

As shown in Table 1, when liquefied argon was allowed to flow down and molten metal 3 was flowed on the trajectory of the flow, an amorphous powder was obtained. However, when liquefied argon is not used, the resulting powder contains a large amount of I-shaped particles,
Furthermore, it was found that the molten gold @6 had condensed onto the rotating body 5, and the surface was severely damaged.

Actual example 2 The material of the rotating body 5 is stainless steel, carbon 10,
Made of silicon nitride and alumina, diameter 101M.

The apex angle was 120°, and liquid nitrogen was used as the liquid cooling medium 8. Also, [rotational speed ti of IJ1 rolling element 5
The other conditions were the same as in Example 1. As the results are shown in Table 2, when a liquid cooling medium (liquefied nitrogen) is not used, the heat am to the rotating body is large, so the rotating body made from silicon nitride and alumina is sprayed. The project broke down immediately after starting and was unable to continue. Furthermore, gold WtO adhesion occurred in rotating bodies made of stainless steel and carbon, even though no damage occurred. Also,
Rotating bodies made from carbon overcome more carbon trapping phenomena than VC without the use of liquefied nitrogen, resulting in powder contamination. Separately, when liquefied four elements were used, good results were obtained for all rotating bodies,
The appearance was also high in the northeast.

Hereinafter, 1: As explained above, according to the present invention, in the method for producing powder by pouring molten metal onto the surface of the rotating body and causing it to become quaternized, a liquid cooling medium is poured over the surface of the rotating body. At the same time, since the molten gold is atomized by flowing onto the liquid cooling medium flowing on the surface of the rotating body,
It is possible to produce extremely good powder especially suitable for powder metallurgy without causing damage to the rotating body or gold plate adhering to the rotating body, and it is already known and fully utilized. This method has the great effect of making it possible to easily produce powder by centrifugal spraying, which has not been done previously.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional explanatory diagram schematically showing an example of the structure of an apparatus used for producing powder according to the present invention, and Fig. 2 is an explanatory diagram showing the trajectory of the flow of the liquid cooling medium and molten metal on the surface of the rotating body. 3 are cross-sectional explanatory views showing other structural examples of the rotating body. 1... Container, 2... Crucible, 6... Molten metal, 5
...Rotating body, 6...Motor, 7...Cooling medium, supply pipe, 8...Liquid cooling medium. Patent Applicant Daido Steel Co., Ltd. Representative Patent Attorney Yutaka Oshio Figure 2 Figure 3

Claims (1)

[Claims] (1) In a method of producing powder by pouring molten metal onto the surface of a rotating body and atomizing it, a liquid cooling medium is flowed on the surface of the front dr2 rotor, and at the same time a liquid cooling medium is flowed on the surface of the front dr2 rotor. A method for producing powder, characterized by flowing molten gold m into a powder and atomizing it.