JPS6025217B2 - Method for manufacturing ultra-quenched metal ribbon - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for rapidly cooling a molten metal alloy to directly produce a tape-shaped continuous solidified body (hereinafter referred to as a ribbon) in a stable manner.

In recent years, a method of manufacturing a ribbon-shaped or linear continuous body by rapidly solidifying a metal alloy from a molten state on a rotating cooling substrate has been actively researched, and some have already been put into practical use.

The feature of this method is that the manufacturing method is extremely simple and energy-saving. Furthermore, since the cooling rate is extremely fast, if the composition of the alloy is appropriately selected, the atomic arrangement will have a long-period structure similar to that of a liquid. A so-called amorphous body that does not have
amorphous). This amorphous material has a number of unique properties that are not found in crystalline materials, and is therefore attracting attention for its applications. In addition, materials that are not amorphous, but whose use was previously impossible or limited due to their poor workability, such as high popsicles and raw steel, can be directly manufactured into thin strips, making it a new method for manufacturing crystalline materials. is also attracting attention. Among these, amorphous alloys have begun to be put into practical use due to their excellent functional properties, but they also have problems.

Unlike crystalline alloys, the structure of amorphous alloys is a non-equilibrium phase, so the properties depend on the history of the material. In other words, it is easily influenced by manufacturing conditions. Among these, the cooling rate is an important factor that affects the properties of amorphous materials. In general, alloys have a cooling rate (critical cooling rate) required to become amorphous depending on their composition, and in order to become completely amorphous, each part of the material must be cooled at a rate that exceeds the critical cooling rate. It needs to be cooled down. A portion cooled at a rate lower than the critical cooling rate crystallizes, causing deterioration of properties. Therefore, if a molten alloy is cooled at a rate close to the critical cooling rate of the alloy, the characteristics of the obtained ribbon will vary greatly due to variations in the cooling rate. For example, it is known that variations in magnetic properties correspond well to variations in cooling rate. For this reason, in order to produce a ribbon with uniform properties, it is necessary to have little variation in the cooling rate in both the longitudinal and middle directions of the ribbon, and to maintain the critical cooling rate in all parts. It must be cooled at a cooling rate that exceeds

Today, the industrially mainstream method for manufacturing ribbons by cooling molten metal on a cooling substrate is the single roll method, but in this method the molten metal is cooled from only one side, so the principle is The disadvantage of this method is that its cooling capacity is inferior to that of the twin roll method.

In other words, since the cooling rate on the free side of the ribbon (the side opposite to the side in contact with the roll) is slow, when the temperature of the roll rises and the cooling capacity decreases, the free side first falls below the critical cooling rate. Crystallization occurs. A similar phenomenon also occurs when there is a locally thick portion. Furthermore, when the cooling rate decreases on the free surface side, not only crystallization is likely to occur, but also surface oxidation may occur, resulting in deterioration of properties. For example, in the case of Fe-based magnetic alloy Fe-(Si, B, C), if easily oxidized AI or other impurities are mixed into the raw material, an oxidized layer will form on the free surface and deteriorate the magnetic properties. It is said. Several proposals have been made in the past to compensate for the lack of free surface cooling associated with the single roll process.

For example, the method of bringing an auxiliary roll into contact with the free surface of the ribbon as shown in Tokusekki Sho 55-3 Ima No. 16, or the method disclosed in Tokukai Sho 54-
A typical method is to press a metal belt against the free surface as shown in Japanese Patent No. 147105.
However, since the contact time of the secondary roll with the ribbon is short, the belt method does not actually contribute much to improving the cooling chamber, and the belt method involves running a metal belt at high speed in synchronization with the main roll. Both have drawbacks, such as being technically difficult. The present invention is simple.

This is an attempt to solve the problem of insufficient cooling of the free surface, which accompanies the roll method, by means completely different from conventional methods. That is, the present invention presses dry ice onto the free surface of the thin strip while it is being cooled, before it peels off from the cooling body.
By increasing the cooling effect and preventing oxidation at the same time, it is possible to produce stable materials with excellent properties such as surface texture and magnetism.

The advantage of the present invention over the previously described secondary method (method of pressing an auxiliary roll or belt) is that the heat removal effect of the cooling medium is large.

Although it is solid, the contact surface can be easily shaped to match the curvature of the ribbon that is in close contact with the roll surface, so the contact surface can be made large. In addition, dry ice has practical advantages in that it has an appropriate hardness and is smooth, so it does not stain the ribbon and does not react with alloys. Next, the method of the present invention will be specifically explained using figures.

FIG. 1 shows a conceptual diagram of the ribbon manufacturing apparatus of the present invention. Although the apparatus of the present invention is based on a single roll method, it can also be applied to a centrifugal quenching method. First, the spouted molten alloy is solidified by a cooling roll 1 and drawn out as a ribbon. When the inside of the ribbon becomes wider, the ribbon generally has a forehead that sticks to the surface of the roll. For this reason, a peeling device 2 is installed at a position as shown in the figure to collect the ribbon. The position to press the dry ice 3 is of course the position 4 where the molten metal is spouted.
and the position where the thin strip peels off, but the optimal position should be changed by using a roll, etc. inside the thin strip. The reason for this is that if you get too close to the ejection part, it will have a negative effect on the shape and surface quality of the ribbon, and if you are too far away, the cooling effect will be reduced and the adhesion between the roll and the ribbon will deteriorate, so the pressing part This is because it becomes thicker as it passes through. It is effective to specifically position the dry ice pressing part between 1 and 20 cm as measured from the position directly below the nozzle.
In order to make it easier to dissipate the CO2 gas vaporized by the heat taken from the ribbon and to improve thermal contact between the ribbon and dry ice,
The effect was further improved when the dry ice 3 was provided with ventilation holes 5 as shown in FIG.

By employing the method of the present invention, the cooling capacity has been improved, and it has become possible to manufacture a thin strip that is thicker than before.

Thick materials have enormous practical advantages, such as increasing the iron core's accounting ratio and shortening the assembly process time. The following will be explained based on examples.

The cooling roll of the example is made of Cu-Be alloy and has a diameter of 60Q and a medium diameter of 70mm.
There are cold rolls of skin.

The structure is such that the cooling water flows inside the 2w ribs from the outer peripheral surface of the roll. The dry ice is shaped in advance so that the surface that will come into contact with the ribbon matches the curvature of the roll surface. In this example, three pieces of dry ice with a rectangular shape of 5 sides on each side to be brought into contact with the ribbon are prepared, and the dry ice is placed at a position of 3 to 2 inches around the roll in all directions, measured from directly below the nozzle. arranged side by side.
The dry ice is controlled so that it is brought into contact with the surface of the ribbon one second after the molten metal is spouted and pressed under a constant pressure. The master alloy Fe 5Si6.5B, 2C, (at %) whose composition had been adjusted in advance was cast into a 5-board ribbon using this apparatus.

For comparison, we also performed casting without cooling with dry ice. Thickness and magnetic properties of ribbon (W, .3/5o
: Magnetic flux density is 1 at 50Hz. (iron loss in esla)
Figure 3 shows the relationship between According to the method of the present invention, the thickness of the plate can be reduced to 45r. 3/5. is 0.15wa ratio/kg
It shows the following excellent properties. On the other hand, when strip cooling with dry ice is not used, as shown in the comparative example in FIG. 3, it is seen that when the plate thickness exceeds 30 mm, the iron loss increases significantly. This shows that the method of the present invention is an extremely effective method for increasing the thickness of a ribbon obtained in an amorphous state.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram showing an example of the present invention, Figure 2 is an explanatory diagram showing an example of dry ice used in the present invention, and Figure 3 is a diagram showing the relationship between plate thickness and iron loss of the present invention and a comparative example. It is a diagram. Figure 2 Figure 3

Claims (1)

[Claims] 1. In a method of continuously manufacturing a thin strip by jetting molten metal alloy onto the outer circumferential surface of a rotating cooling body and rapidly cooling it, the free flow of the thin ribbon during cooling is removed before the thin ribbon peels off from the cooling body. A method for producing ultra-quenched metal ribbon of excellent quality and stability, characterized by pressing dry ice on the surface (the surface opposite to the surface in contact with the cooling body) to improve the cooling effect and prevent oxidation.