JPS62116733A - Refining method for yttrium containing alloy - Google Patents

Abstract

PURPOSE:To stably refine highly clean alloy contg. Y, by holding molten Y- contg. alloy in nonoxidizing atmosphere while using vessel whose inner surface is composed of CaO quality refractory contg. a specified ratio of CaO. CONSTITUTION:At refining Y contg. alloy, vessel whose inner surface is composed of CaO quality refractory of >=90wt%, favorably >=95wt% CaO content ratio is used, and molten Y contg. alloy is held under nonoxidizing atmosphere (Ar, He, etc.). As Y contg. alloy, alloy with element having lower affinity with oxygen than Y, contg. >=about 0.5% Y, and Co-22Cr-11Al-0.8Y, etc., are exemplified. To CaO quality refractory contg. >=90% CaO, calcia, CaO enriched dolomite, etc., are used. In this way, high purity Y contg. alloy can be reined without contamination by impurity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention relates to a method for producing an alloy containing yttrium (Y), and more particularly, relates to a method for producing a Y-containing alloy that can obtain a highly pure alloy. .

[Prior art] Y can improve the heat resistance and high-temperature characteristics by incorporating it into various alloys, so in recent years Y has been widely used.
Containing alloys are used in various fields.

For example, research has been conducted to improve the high-temperature properties of superalloys such as Ni-Cr alloys and Fe-Cr alloys by adding Y, and it has also been used to improve the properties of various metal materials for thermal spraying. Y is added (for example, NI
-Cr-An-Y alloy, Co-Cr-An-Y alloy).

[Problems to be Solved by the Invention] Conventionally, it has been believed that such Y-containing alloys can be melted in a crucible, but due to the high activity of Y, alloy contamination by refractory furnace materials that come into contact with the molten metal may occur. Generation of Y2O3-based oxide, Y
Problems such as a decrease in content have occurred, and it has been difficult to obtain products of stable quality.

For example, magnesia and graphite refractory materials are generally used as high-frequency furnace materials for melting.

This causes an increase in the concentration of oxygen and carbon in the molten metal as described below.

MgO (furnace material) → Mg (gas) + 0 (in molten metal) C (furnace material) → C (in molten metal) In addition, MgO reacts with Y in the molten metal as shown below, reducing the Y content and reducing the molten metal. cause pollution.

3 M g O+ 2 Y → 3 M g + Y 20
3. The molten metal is similarly contaminated with other high-resistance materials such as alumina and zirconia containing silica.

Asu203+2Y→2 A fL+ Y 2033 Z
r O2+ 4 Y + 3 Z r + 2 Y
2033Si02+4Y→3 S i + 2 Y 2
03 For this reason, for example, N
When an i-Cr-An-Y alloy is used as a thermal spray powder, there is a problem in that a coating having desired corrosion resistance and heat resistance cannot be formed due to impurities mixed into the alloy.

[Means for Solving the Problems] In view of the above-mentioned conventional circumstances, the present invention provides an industrially extremely advantageous melting method for Y-containing alloys, which includes: The inner surface is CaO
A method for melting a yttrium-containing alloy, which comprises holding a molten yttrium-containing alloy in a non-oxidizing atmosphere using a container made of a CaO refractory having a content of 90% by weight or more.

The main points are as follows.

The present invention will be explained in detail below.

In addition, in this specification, "%" represents "weight %".

In the present invention, Y-containing alloys include, for example, A-cross, Cr,
Fe, Mn, Ni, Cu, V.

Co, Ti, Ta, W, Sn, Zr, Mo, Nb
, 1 of elements with lower oxygen affinity than Y such as Si and Bi
An alloy of a species or two or more species and Y, the Y content being 0.
5% or more.

Among Y-containing alloys, the following examples are known as Y-containing alloys for thermal spray materials.

Co-22Cr-11A1. -0.5YCo-19Cr
-6AJl-0,8Y Ni-19Cr-6Al-0,5Y Ni-22Cr-LOAM-1,0Y Ni-23Co-18Cr -13A-0.6Y Other high conductivity, heat-resistant alloys such as Cu-0,1~ 0.2
A Sn-0,5Y alloy has been developed.

In the present invention, the inner surface of such a Y-containing alloy is C.
Using a container made of CaO refractory with an aO content of 90% or more, melt by heating in a non-oxidizing atmosphere (e.g. argon, helium, etc.) using a conventional method such as high frequency or low frequency induction heating. Let it melt.

In the present invention, examples of the CaO refractory material having a CaO content of 90% or more and constituting the inner surface of the container used for melting the Y-containing alloy include calcia (Cab) and CaO-enriched dolomite.

As CaO, fused calcia is preferable because it is dense. Also suitable is calcia (Cab) obtained by burning quicklime, limestone, or slaked lime.

The higher the CaO content in such CaO refractory materials,
In the present invention, it is preferable to use a container made of a CaO-based refractory material with a CaO content of 95% or more, since impurity generation is small and contamination of the molten metal is more reliably prevented.

[Action] CaO has extremely high stability against Y, and CaO+2Y
Since the reaction +3Ca+Y20a is extremely difficult to proceed, MgO1AJ12
0y, Z ros+, there is almost no reaction with Y to produce Y oxides, and therefore there is little chance of reducing Y in the Y-containing molten alloy or contaminating the molten metal with impurities. When Ca is reduced by Y and a small amount of Ca is produced, it combines with nonmetallic elements such as 0 in the molten metal and brings about a refining effect in which it is removed from the molten metal.

In addition, CaO-based refractories tend to react with oxides on the furnace wall, and can absorb oxides in the Y-containing alloy molten metal, greatly reducing the amount of oxides present. It becomes possible to obtain an alloy.

Therefore, by using a container whose inner surface is made of such a furnace material with a high CaO content, it is possible to successfully melt and produce a Y-containing alloy.

[Examples] The present invention will be explained in more detail with reference to Examples and Comparative Examples. ).

Example 1. Comparative example l Ni-19wt%Cr-6wt%A1-0.8wt%Y
L kg of alloy is placed in a CaO crucible (Ca099% electric fusion product), A
They were placed in a 1203 quality crucible and an MgO crucible, and placed in an internally heated high-frequency induction furnace with an output of 10 kW and a frequency of 50 kHz, and melted in an argon atmosphere. After 10 minutes, 0, S, Y, AM, Mg, Ca, Si and inclusion contents were analyzed by chemical analysis and fluorescent X-rays. The results are shown in Table 1.

Table 1: For 0, S, Mg, and Ca, ppm and others are weight %. B: For inclusion content, the purity level (%) according to JIS G0555 is shown.

From Table 1, according to the CaO crucible, the content of 0, S, Si which is an impurity metal component, and other inclusions is small, and the content of Y
It is clear that a Y-containing alloy with a high yield and high purity can be obtained.

[Effects of the Invention] As detailed above, the method for producing a Y-containing alloy of the present invention is as follows:
The inner surface of the molten Y-containing alloy has a CaO content of % or more.
It is kept in a non-oxidizing atmosphere in a container made of high quality refractory material, and it is possible to obtain a highly clean Y-containing alloy in an extremely stable manner.

According to the method of the present invention, (1) it is possible to easily obtain a Y-containing alloy that is low in oxygen, low in sulfur, and has a small amount of inclusions;

(2) Therefore, the resulting alloy has extremely high properties and can exhibit excellent corrosion resistance and heat resistance as a thermal spray material.

■ An alloy with extremely homogeneous composition can be obtained.

■ Easily re-melt and cast Y-containing alloys.

Various effects such as these are achieved, and it is extremely advantageous industrially.

The present invention can also be successfully applied to melting return material containing Y.

Claims (1)

[Claims] (1) When melting the yttrium-containing alloy, the molten yttrium-containing alloy is held in a non-oxidizing atmosphere using a container whose inner surface is made of a CaO refractory with a CaO content of 90% by weight or more. A method for producing a yttrium-containing alloy.