JPS61243137A - Manufacture of cobalt alloy containing boron - Google Patents

Abstract

PURPOSE:To manufacture an inexpensive cobalt alloy contg. boron and little impurities by adding boron oxide and a specified amount of calcium to molten cobalt, reducing the boron oxide, and lowering the calcium content in the molten under reduced pressure. CONSTITUTION:Boron oxide and calcium by an amount 0.9-1.5 times the amount required to reduce all of the boron oxide are added to molten cobalt or a molten cobalt alloy. The amount of calcium required to reduce boron oxide is about 3mol per 1mol B2O3. After the boron oxide is reduced, the remaining calcium in the molten metal is evaporated at >=1,368K temp. under reduced pressure to lower the calcium content.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a boron-containing cobalt alloy.

Closely related amorphous alloys and ferromagnetic alloys containing boron are being sought as raw materials for rare earth magnets.

Conventional manufacturing methods can be divided into a method in which elemental boron is added to a ferromagnetic alloy and a method in which boron oxide is reduced with At or carbon in a molten metal. Among these methods, the former method has the advantage that elemental boron is expensive but has few impurities.The latter method is cheap but contains reducing agent as an impurity.
It has the disadvantage that its uses are limited because it contains carbon and carbon.

An object of the present invention is to provide an inexpensive method for producing a boron-containing cobalt alloy with few impurities.

In the present invention, boron oxide and calcium in an amount of 0.9 to 1.5 times the amount required for reducing the total amount of boron are added to molten cobalt or cobalt alloy to reduce boron oxide. Disclosed is a method for producing a boron-containing cobalt alloy, characterized in that the amount of calcium in the molten metal is reduced by reducing the pressure and then reducing the pressure.

The present invention employs a method of reducing the pressure of the molten metal in order to reduce the amount of Ca, which is a reducing agent, remaining as an impurity in the molten metal.
B, Ca [2400K each.

By reducing the pressure at a temperature of 3100, 1250, and 1368, which is the eutectic point of Co-B,
It was discovered that Ca evaporates easily, leading to the present invention.

On the other hand, in the method using AA and C, the temperature at which the vapor pressure of At and C becomes 10 Torr K is 2100 and 3
400, which is extremely high, so it cannot be expected that impurities will be reduced by reducing the pressure.

The invention is based on the following chemical reaction.

From BzO3+ 30a → 2B + 30aO, B
Ca3m for 2O,51 mol (69,61)
ol(12OJ') is the amount required to reduce the total amount of boron. The present inventor has proposed B2O. If the entire amount is returned.

In the system resulting in 4 wt% B-Co, the amount of Ca is 0.8, 0.9, 1.0, 1.
2, 1.4.

When we conducted an experiment in which B was added 1.5 and 1.6 times and measured the yield of B, the results were 0.71, 0.83, 0.91, and 0.92, respectively.
゜0.92, 0.94, 0.93. The amount of Ca before depressurization is 0.4, 0.5, 0, respectively.
．． 7.

It became 0°9*1.8-2.8-4.8 wt*. The amount of Ca after reducing the pressure to I Torr for 1 hour is 0.01°0.02, 0.03, 0.07, 0, respectively.
．． 12, 0.22, and 0.39 wt%. Based on this experimental result, the amount of calcium required for boron reduction is 0.
．． It was determined that a calcium amount of 9 times or more and 1.5 times or less was appropriate.

The lower the pressure during decompression, the better, but industrially it is 10-! 1
Torr to about 10' Torr is desirable. Within this range, the device can be easily constructed and sufficient effects can be expected. The vacuum holding time is not critical, as long as zero image pressure is reached.

In the present invention, the term "Co alloy" refers to an alloy containing at least 50% Co by weight, with the remainder consisting of elements that are normally alloyed with Co and inevitable impurities.

Hereinafter, the present invention will be explained in detail by way of examples.

Example Cobalt 500I was melted in an aluminum crucible by high frequency heating in the atmosphere. A mixture of 2 mol of B2O3 powder and 6 mol of Ca powder was packed into a cobalt/fide having an outer diameter of 2O and an inner diameter of 10m, and stirred in the molten metal. The molten metal reacted violently and CaO floated to the surface.

At this time, in order to prevent the temperature of the molten metal from rising rapidly, the cobalt arm is made thicker than necessary. At the end of the reaction, the molten metal was preheated, regrouped and depressurized to prevent slag from entering the aluminum crucible, and heated to 10 Torr in 45 minutes.
When rK was reached, heating was stopped and solidification was continued. The yield of boron is 91%, and the amount of magnesium is 0.02%.
It was wt%.

The present invention makes it possible to produce a boron-containing cobalt alloy with few impurities, and is believed to be of great industrial benefit.

Applicant: Hitachi Metals, Ltd.

Claims (1)

[Claims] 1. Boron oxide and the amount of 0 necessary for reducing the total amount of boron
．． Boron characterized by reducing the amount of calcium in the molten metal by introducing 9 times or more and 1.5 times or less calcium into molten cobalt or cobalt alloy, reducing the boron oxide, and then reducing the pressure. A method for producing a cobalt-containing alloy. 2. The amount of Ca required for the reduction of boron is B_2O_3
The method for producing a boron-containing cobalt alloy according to claim 1, wherein the amount is about 3 mol per 1 mol. 3. The method for producing a boron-containing cobalt alloy according to claim 1, wherein the pressure reduction is performed at a temperature of 1368 K or higher.