JPH0442885A - Crucible for preparing ferrite single crystal - Google Patents

Abstract

PURPOSE:To reduce elution of platinum and platinum particles from mixing into crystals by lining a crucible body composed of platinum (alloy) with a platinum (alloy) reinforced with an oxide dispersed therein. CONSTITUTION:The inside of a crucible body 7 composed of platinum (alloy) 8 prepared by joining a cylindrical part 1' to a conical part 3' through a weld 4 is lined with a liner 9 of platinum (alloy) reinforced with an oxide dispersed therein.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The disclosed technology belongs to the technical field of the structure of a crucible for growing ferrite single crystals for dissolving oxides such as Fe203 powder.

<Summary of the gist> This invention relates to a crucible for producing a ferrite single crystal in which oxide powder such as Fe2O3 is charged and melted by heating at a predetermined high temperature for a long time. Alternatively, the invention relates to a crucible for producing a ferrite single crystal that has a double structure in which the inside of the crucible body made of a platinum alloy is lined with oxide dispersion strengthened platinum or an oxide dispersion strengthened platinum alloy, such as a cladding.

<Prior Art> As is well known, ferrite used in heads of tape recorders, video decks, etc. requires a ferrite single crystal, which is obtained by melting ferrite oxide powder in a suspended crucible. Conventionally, materials for single crystal growth crucibles for dissolving oxides such as ferrite have been made of platinum or platinum-rhodium alloys, which are chemically stable and resistant to acids and alkalis. In order to obtain the desired single crystal, it is necessary to put oxide powder such as ferrite into a nuclide crucible and heat it for several days at a temperature close to the melting point of platinum or platinum alloys, that is, at a high temperature of 1600°C or higher. be.

<Problem to be solved by the invention> If platinum or platinum-rhodium is used as the material for the crucible that is heated to such high temperatures for a long period of time, volatilization of platinum is unavoidable, and the platinum or platinum alloy in the crucible is eluted into the ferrite melt. Therefore, in order to improve the magnetic properties of the ferrite single crystal, it is preferable that the number of mixed platinum particles per unit area be as low as possible, but
Practically speaking, there is a problem in that it is difficult to obtain a high-quality single crystal containing less platinum, which is desirable to have 10 or less crystals.

Also, although platinum and platinum alloys are resistant to acids and alkalis, silver, sulfur, iron, and gold are highly reactive to platinum.

Silver has the disadvantage of being easily contaminated and corroded.

To deal with this, not only is there less volatilization of platinum, but also
Practical use of crucibles for producing ferrite single crystals made of oxide dispersion-strengthened platinum or oxide dispersion-strengthened platinum alloys have the advantages of high resistance to contamination and corrosion, and the ease with which ferrite solidified after melting peels off from the crucible. desired.

As shown in FIG. 2, the crucible for producing a ferrite single crystal has a shape in which a cylindrical part 1 is formed of a plate material, an edge 2 of the plate is welded, and the cylindrical part 1 is integrally formed with the crucible. Welding 4, 4, etc. of the conical part 3 of the joint is required.

However, since oxides are uniformly dispersed in the platinum or platinum alloy in the crucible 5 for producing ferrite single crystals, the oxides dispersed during the melting of the material during the welding necessary for making the crucible are There is an inconvenience that the sludge oxides float out and cause pinholes and other so-called "sakae" to occur due to entrainment, and it is also necessary to visually inspect the molten surface during welding with an oxygen burner, etc. However, the oxide film covering the molten surface makes it difficult to visually inspect the melted surface, resulting in lower workability, and also has the disadvantage of increasing costs due to deterioration of manufacturing conditions.

Furthermore, crucibles made from oxide dispersion strengthened platinum or oxide dispersion strengthened platinum alloys tend to be molded with their inner surfaces rough due to their material nature, so melting under harsh conditions at high temperatures and long periods of time can cause platinum and platinum to melt. There was a negative point that alloy particles were more likely to be mixed into the ferrite from the crucible.

Furthermore, there was also the problem that ferrite leaked out from between the platinum particles.

<Object of the Invention> The object of the invention is to solve the problem of a crucible for producing a ferrite single crystal made of platinum or platinum-rhodium alloy, an alternative oxide dispersion strengthened platinum, or an oxide dispersion strengthened platinum alloy based on the above-mentioned prior art. This is a technical problem to be solved, and while making full use of the advantages of the oxide dispersion strengthened platinum or oxide dispersion strengthened platinum alloy, we will remove the conditions that inhibit it, and improve the elution of platinum particles from the crucible. It prevents contamination into the inside and produces high quality ferrite single crystals, and
Provides an excellent crucible for producing ferrite single crystals that benefits the field of metallurgy technology application in the metal industry by making it possible to manufacture crucibles that have good welding operability and workability, are strong at low cost, and can prevent leakage. This is what I am trying to do.

<Means/effects for solving the problem> In order to solve the above-mentioned object, the structure of the present invention, which is summarized in the above-mentioned claims, is to solve the above-mentioned problem by using platinum or a platinum alloy as a crucible body, The inner surface of the main body is lined with a 10 micron thin film of oxide dispersion strengthened platinum or oxide dispersion strengthened platinum alloy with cladding, etc. to reduce costs, and the cylindrical part and improves the weldability of the conical part etc. that is integrally connected to the cylindrical part, eliminates the occurrence of "crows" such as pinholes, has little platinum elution, does not cause contamination or corrosion, and is made of ferrite particles made of platinum particles. Technical measures have been taken to obtain high-quality ferrite single crystals without infiltration into the crystal or leakage through platinum particles.

<Example> Next, an example of the present invention will be described below with reference to the drawing of FIG.

In the embodiment shown in FIG. 2, 5' is a crucible for producing a ferrite single crystal, which constitutes the gist of the present invention, and a conical part 3' is integrally connected to the lower side of the cylindrical part 1' via a weld 4. .

Of course, the cylindrical part 1' is made by forming a plate material and welding the edges.

The crucible body 7 of the cylindrical part 1'2 and the conical part 3' is made of platinum or a platinum alloy 8, and the inside of the crucible body 7 is made of oxide dispersion-strengthened platinum or oxide dispersion-strengthened platinum with a cladding. It is lined with an alloy liner 9.

Specific aspects of the crucible 5' are shown in Table 1 below.

The liner material 9 of the present invention has an inner surface lined with oxide dispersion strengthened platinum, and the outer side of the liner 9 is the platinum or platinum alloy of the crucible body 8. For this reason, the cylindrical portion 1',
The welding process for the conical part 3' that is integrally connected to this can be performed in the same way as conventional welding for platinum or platinum alloys, and the molten surface can be easily observed when welding using an oxygen burner or the like. Workability and operability are good.

The crucible 5' used for growing ferrite single crystals must be adaptable to harsh conditions such as being hung on a hanger for a long time at high temperatures.

Therefore, the crucible of the present invention has a so-called double structure of a crucible body 8 made of platinum or a platinum alloy and a lining liner 9 made of oxide dispersion strengthened platinum or an oxide dispersion strengthened platinum alloy. Not only does it strengthen itself, but it also helps prevent leakage between platinum particles such as molten ferrite.

Next, evaluation of the crucible of the present invention according to the above-mentioned Examples will be explained as follows.

1) Cut the central part of the platinum-containing inspection ferrite ingot into approximately 10,11111 pieces, mirror-wrap the inspection surface, and use a metallurgical microscope x 100.
Scanning was performed a total of five times in the X-axis and Y-axis directions at magnification, and the total amount of platinum within the field of view was counted and converted to number/d.

2) Comparison test of welding operability The cylindrical part 1' of the crucible 5' of this invention (peripheral welding)
, and as a result of overlapping and welding the cylindrical portion 1' and the conical portion 3', the operability of welding work etc. is improved compared to conventional platinum and,
It was on the same level as a platinum alloy crucible.

Therefore, the conventional platinum or platinum alloy crucible,
Comparison data with a crucible lined with oxide dispersion strengthened platinum or oxide dispersion strengthened platinum alloy material of the present invention and a reliner are shown in Table 2 below.

As shown in Table 2 in the margin above, the number of platinum particles is extremely small and is sufficient for practical use.

<Effects of the Invention> As described above, according to the present invention, platinum or a platinum alloy is used as the crucible body, and oxide dispersion-strengthened platinum or
By using a crucible for producing ferrite single crystals lined with an oxide dispersion-strengthened platinum alloy, there is less platinum eluting from the crucible under the same conditions as conventional crucibles, less platinum particles are mixed into the crystal, and there is less contamination and corrosion. However, the excellent effect of obtaining a high quality ferrite single crystal can be achieved.

Furthermore, the crucible according to the present invention eliminates welding operability, which was a conventional weakness of oxide dispersion strengthened materials, compared to conventional platinum or
It has the same effect as a crucible made of platinum alloy material, and in addition, the double structure increases the strength of the crucible, and it also has the effects of a composite material, such as preventing leakage of ferrite from between platinum particles. It was noticeably recognized.

The material of the crucible of the present invention is such that even if the crucible is exposed to high temperatures for a long time, the crucible is lined with oxide dispersion-strengthened platinum or oxide dispersion-strengthened platinum alloy.
There is little change in the inner surface properties and it can be made as smooth as possible, which has the effect of reducing the mixing of particles of platinum or platinum alloy, which is the material of the crucible, into the ferrite.

In order to form a film-like lining of, for example, 10 microns, with oxide dispersion strengthened platinum or oxide dispersion strengthened platinum alloy, oxide dispersion strengthened platinum is originally used for conventional platinum,
Alternatively, compared to platinum alloys, oxide dispersion strengthened platinum, which is more expensive due to different manufacturing conditions,
Alternatively, by lining it with a thin layer of oxide dispersion-strengthened platinum alloy, there is an advantage in that it is possible to suppress the increase in cost as much as possible.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an embodiment of a crucible according to the invention, and FIG. 2 is a perspective view of a crucible according to the prior art. 8... Crucible body 5'... Crucible 9...
Inner liner Figure 2 8... Crucible body 9... Inner liner 5'... Crucible

Claims (1)

[Claims] A crucible for producing a ferrite single crystal, in which a crucible body made of platinum or a platinum alloy is lined with oxide dispersion-strengthened platinum or an oxide dispersion-strengthened platinum alloy.