JPS6112854A - Rapidly cooled and solidified thin strip of permanent magnet and its manufacture - Google Patents

Abstract

PURPOSE:To manufacture easily and with low cost an extremely thin strip of Fe-Cr-Co permanent magnet superior in magnetic property, by allowing molten metal of Fe-Cr-Co alloy to flow down on cooling body revolving at high speed to cool ultrarapidly said bath. CONSTITUTION:The molten metal 3 of alloy steel contg. 10-35% Cr, 5-35% Co, or further 0.01-5.0% at least one kind selected from B, C, Si, Al, P, Mo, W, Mn, Ti, V, Nb, Zr, Sn, Zn is allowed to flow down on a single roll 1 revolving at high speed or cooling body consisting of twin rolls 2, 2, cooled ultrarapidly at >=10<3> deg.C/sec rate to solidify it in a strip shape 4 of <=0.5mm. thickness. This is age treated in magnetic field under impressed magnetic field of 1-30Ko3 condition. The pemanent magnet sheet superior in magnetic property is manufactured with low cost and extremely simply compared with conventional method.

Description

Detailed Description of the Invention (Technical Field) The technical content described in this specification regarding a permanent magnet rapidly solidified ribbon and its manufacturing method is directed to permanent magnets, especially Fe-
By applying the liquid quenching direct plate manufacturing method to the production of Or-00 series permanent magnets, it is possible to easily obtain an extremely thin rapidly solidified ribbon with excellent magnetic properties at a low cost.

(Technical background) Fe-Or-Co magnets have the great advantage of being superior in plastic workability and machinability compared to At-Ni-Co magnets. However, since this magnet is a spinodal decomposition type magnet, the process is quite complicated. That is, after pouring molten steel prepared to a predetermined composition,
The steel structure is subjected to solution treatment with C to make the steel structure into an α single phase, then water-cooled, and then subjected to aging treatment in a magnetic field. Spinodal decomposition occurs in this aging treatment process in a magnetic field, resulting in α resistance,
It becomes a two-phase separated structure of +α2 and exhibits ferromagnetism. Note that after this, if necessary, cold working and aging treatment may be performed, or hot or cold working may be performed before performing aging treatment in a magnetic field.

As mentioned above, Fe-ar-co magnets require high-temperature and long-term processes such as solution treatment and magnetic field aging treatment in the manufacturing process. Improvement was desired.

Recently, there has been a particularly high demand for ultra-thin permanent magnets in components such as flat step motors for floppy disk drives and thin speakers. However, even though Fe-ar-co thread magnets are highly workable, many rolling processes are required to make them into thin strips with a thickness of about 0.5 J or less, which leaves problems with workability and costs. There was also the disadvantage of being high.

This invention advantageously solves the above-mentioned problems, and uses Fe-Or-Co based magnets that are extremely thin and have excellent magnetic properties.
The purpose is to propose this along with a simple manufacturing method.

(Effect of the invention) In other words, this invention is Or? 10 to 35% by weight (hereinafter simply expressed as %) and Co: 5 to 35%,
Sometimes additionally B, O, Si, At, , P
, Mo.

W t Mnt Ti t V , Nb , Zr
, Sn and zn in a range of 0.01 to 5.0%, and the remainder has a composition of substantially F'e, the ribbon comprising: A permanent magnet rapidly solidified ribbon characterized in that it is obtained by forcing the rapid solidification of molten steel having the above composition by receiving a falling flow of molten steel having the above composition on a cooling body whose cooling surface is updated and moved at high speed.

This invention also provides cr: io~35% and Co
: Molten steel with a composition containing 5 to 35% is continuously supplied onto a cooling body whose cooling surface is updated at high speed, and the temperature is increased to 108°C/
After rapidly solidifying into a thin ribbon at a cooling rate of S or higher, the temperature is 8300-800℃ and the applied magnetic field is 1-80K.
This is a method for producing a permanent magnet rapidly solidified ribbon, which comprises subjecting it to aging treatment in a magnetic field under OE conditions.

This invention will be specifically explained below.

First, in this basic explanation, the reason why the component composition is limited as described above is as follows.

Or: 10-35% Or is a useful component that forms a magnetically expelling matrix, but if its content is less than 10%, satisfactory solutionization cannot be achieved even by rapid solidification; %, the residual magnetic flux density decreases and the performance as a magnet deteriorates, so the Or content was limited to a range of 10 to 35%.

Co: 5-35% Co is added as a ferromagnetic component along with Fe, but if the amount added is less than 5%, spinodal decomposition, which is a characteristic of the magnet of this invention, will occur. On the other hand, if the Co content exceeds 35%, sufficient solutionization cannot be expected, so the Co content was set in the range of 5 to 35%.

The basic components have been explained above, but this other side component
A small amount of one or more selected from Nb, Ti, Zr, Mn, Sn, and Zn can also be added. All of these elements effectively contribute to enhancing the anisotropic decomposition in the <100> direction during aging treatment in a magnetic field, but if the amount added is less than 0.01%, the effect of addition is poor; %, the residual magnetic flux density decreases, so the amount added should be 0.00000000 for both single addition and combined addition. It is necessary to set the range of O1 to 5.0%.

Next, the manufacturing method of this invention will be explained.

Now, the molten steel prepared to have the preferred composition as described above is
First, a cooling body whose cooling surface moves at high speed, for example, the first
Single roll 1 and twin rolls 2 and 2 shown in Figures and Figure 2
It is supplied from a nozzle 8 onto the roll surface of /, and is rapidly solidified into a ribbon 4.

At this time, the cooling rate must be set to No. This is because oxidation is so severe that it is difficult to obtain a healthy product.

In addition, in forming the ribbon, the thickness of the ribbon can be adjusted by changing the diameter and material of the roll, the number of rotations, the temperature of the molten steel, the nozzle diameter, etc. If the plate thickness exceeds 0.5 mm, the cooling rate will be slow and it will be difficult to form a thin strip, while if the thickness is less than 0.6 mm, the continuous thin strip will become slant-like. Plate thickness is 0.0
It is preferable to set it as 2-Q, jam degree/degree.

By applying the liquid quenching method in this way, it is possible to directly obtain a ribbon, which makes it possible to omit not only the casting and rolling processes but also the high-temperature solution treatment process that was previously considered indispensable. It has become.

The obtained rapidly solidified ribbon is then subjected to an aging treatment in a magnetic field to cause spinodal decomposition and increase the coercive force. The treatment temperature for this aging treatment in a magnetic field is set in the temperature range of 300 to 800°C, at which spinodal decomposition occurs, but even in this temperature range, spinodal decomposition does not occur if the magnitude of the applied magnetic field is less than 1 koe. On the other hand, the applied magnetic field was limited to a range of 1 to 130 koe, since the effect reaches saturation even if the magnetic field is applied in excess of 80 koe, and the cost increases, which is disadvantageous for production on an industrial scale.

In order to further improve the properties, it is desirable to continue the aging with multi-stage heat treatment after the aging treatment in a magnetic field.

Since the ribbon thus obtained is obtained by rapid solidification, it has extremely few inclusions and precipitates, and therefore the aging time can be shortened.

(Example) Example 1 Molten steel having the composition shown in Table 1 was rapidly solidified by a single roll method at a cooling rate of 10"C/S to obtain a thickness of 0.
It was made into a thin strip with Q5ms and width: 2omm. Next, such a ribbon was subjected to an aging treatment in a magnetic field at 680''C for 80 minutes while applying a magnetic field of 2.5 kOe in the longitudinal direction.

Table 1 shows the results of investigating the magnetic properties of each product ribbon thus obtained.

For comparison, Table 1 also shows the results of an investigation on conventional materials of the same shape obtained by casting, rolling, and solution treatment according to conventional methods.

Table 1 [ [ As is clear from the results in Star Table 1, the ribbon according to the present invention is generally superior in residual value-east density and coercive force compared to conventional materials. Note that some component compositions may have inferior residual magnetic flux density, but in this case, coercive force is significantly superior.

Example 2 Molten steel having the composition shown in Table 2 was rapidly solidified by the twin roll method at a cooling rate of lθ °C/S to obtain a thickness of 0.
It was made into a thin strip of 15 mm and width: 3Qmtn. Then, such a thin plate was subjected to an aging treatment in a magnetic field at 680°C for 80 minutes while applying a magnetic field of 3.0 koe in the longitudinal direction. Thereafter, it was further aged at 500'C for 10 hours.

Table 2 shows the results of investigating the magnetic properties of each product ribbon thus obtained.

For comparison, a similar investigation was conducted on conventional materials of the same shape obtained by casting, rolling, and solution treatment according to conventional methods, and the obtained results are also listed in Table 2.

Table 2 - (Effects of the Invention) Thus, according to the present invention, the magnetic properties of the Fe-Qr-Q□-based permanent magnet ribbon can be significantly improved compared to the conventional method, and moreover, the manufacturing process is , it is possible to realize a significant omission of processes, and it is also effective in reducing costs.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the manufacturing procedure of a rapidly solidified ribbon by a single roll method, and FIG. 2 is an explanatory diagram of the manufacturing procedure of a rapidly solidified ribbon by a twin roll method.

Claims (1)

[Claims] 1. A ribbon containing 10 to 35% by weight of Cr and 5 to 35% by weight of Co, with the remainder being substantially Fe, the ribbon having a cooling surface. 1. A permanent magnet rapidly solidified ribbon, characterized in that it is obtained by receiving a falling flow of molten steel having the above composition on a cooling body that renews at high speed, and forcing the molten steel to rapidly solidify. 2. Contains Cr: 10-35% by weight and Co: 5-35% by weight, and contains B, C, Si, Al, P, Mo, W, Mn, Ti, V,
Containing at least one selected from Nb, Zr, Sn and Zn in a range of 0.01 to 5.0% by weight,
The remaining part is a ribbon having a composition of substantially Fe, and the ribbon receives a falling flow of molten steel having the composition on a cooling body whose cooling surface renews and moves at high speed, forcing it to rapidly solidify. A permanent magnet rapidly solidified ribbon characterized by being a permanent magnetic rapidly solidified ribbon. 3. Continuously supply molten steel with a composition containing Cr: 10 to 35% by weight and Co: 5 to 35% by weight onto a cooling body whose cooling surface renews and moves at high speed, and cools the steel to a temperature of 10^3°C/S or more. After rapidly solidifying into a thin ribbon at a cooling rate of
1. A method for producing a rapidly solidified permanent magnet ribbon, which comprises performing an aging treatment in a magnetic field at a temperature of 00 to 800° C. and an applied magnetic field of 1 to 30 KOe.