JPS6196045A - Manufacture of calcia porous body and high-purity alloy by use thereof - Google Patents

Abstract

PURPOSE:To attain the improvement of the filtration capacity, especially the molten alloy-filtering capacity, by incorporating a specified amount or more of CaO to the surface layer part of a skeletal structure, composed of calcia, of a porous body having three-dimensional network structure. CONSTITUTION:>=40% CaO is incorporated to the surface layer of a a skeletal structure of a porous body having three-dimensional network structure, or further MgO, CaF2, and Al2O3 may be incorporated by 0-60%, 0-40%, and 0-60%, respectively. When a molten alloy, e.g. that of Fe, Co, or Ni base, is brought into contact with this porous body, a high-purity molten alloy can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a calcia porous material and a method for producing a high purity alloy using the same.

C Conventional technology 1 In the production of various metal or alloy products such as aluminum, fj], zinc, etc., if high purity is required for the product, 9
Usually, during the melting stage of these metals or alloys, the molten metal is filtered to remove impurities.

Even in the casting of superalloys such as Ni-based superalloys, acetate-based inclusions, slag compositions, etc. generated during melting are removed by filtering during pouring.

Conventionally, ceramic foam filter materials have been known as filter materials for molten metal, and filter materials made of materials such as alumina, mullite, spinel, zircon, and zirconia have been widely used, and are currently being further researched and developed. be.

Ceramic foam filter material is a porous body having uniform continuous pores, for example, foamed polyurethane filter material-1,
'(Manufactured by impregnating ceramic slurry, drying, and firing (T industry materials vol. 1.31. No.
, 8. P, 54).

However, ceramic foam filter material -f) The filtration capacity per IJ filtration area is large, therefore.

The filtration cost per weight of filtered substance can be significantly reduced.

2) Because of the uniform skeletal structure, there is little variation in the S vortex effect.

・3) Since the amount of filtration per filter is large, it can be replaced less frequently.

・4) The amount of train is small, making it easy to handle alloy changes.

・Since the heat capacity of the filter is small and the preheating time is short, less energy is required for preheating, enabling energy savings and lower operating costs.

It has the following characteristics and is attracting attention in various fields.

[Problems to be Solved by the Invention] Such conventional ceramic foam filter materials remove nonmetallic inclusions in molten metal simply by mechanical filtration or physical adsorption. However, in cases where it is required to obtain a molten metal of extremely high purity, such as in the production of Ni-based super superalloys, such mechanical filtration alone is insufficient, and a filter with better filtration ability is required. material is desired.

[Means for Solving the Problems] In the first invention, in order to significantly improve the filtration ability of a ceramic porous body, in addition to mechanical filtration and physical adsorption, the porous body is provided with chemical filtration and physical adsorption. At least the surface layer of the skeleton has a calcia composition in order to impart the effect of adsorption and absorption.

A calcia-based porous gas characterized in that, in a porous body having a three-dimensional network structure, at least the surface layer of the network skeleton contains 40% or more of CaO.

This is a summary of the following.

In a second aspect of the invention, a molten alloy is brought into contact with the porous body according to the first aspect III.

A porous body having a three-dimensional network structure and at least the surface layer portion of the network skeleton containing 40% or more of CaO,
The gist of the present invention is a method for producing a high-purity alloy, which includes a step of bringing molten alloy into contact.

The present invention will now be described in detail.

The porous body of the present invention has a three-dimensional network structure.

There are no particular restrictions on its shape.

In addition, for filtration of molten metals or alloys,
It is preferable to have heat resistance that can withstand the temperature of the molten alloy, and strength that can withstand the pressure of the molten metal applied during filtration.

In the present invention, the porosity of the porous body is preferably about 50 to 90%. If the porosity is high, a! Although the overperformance is high, the strength of the porous body is reduced. On the other hand, when the porosity is low, the 1 strength increases, but the S overpass capacity decreases. Particularly preferred pores (l is 70 to 90% 4° I').

The Calcia porous body of the present invention is three-dimensional,
At least the surface layer of the skeleton of the I structure contains 40% CaO.
% or more.

The surface layer of this skeleton may be calcia containing 40% or more of CaO, and may also contain MgO.

CaF, AM, 03, etc., respectively, Q-8o%, 0~
The composition of the skeletal surface layer, which may be contained in the range of 40% and 0 to 60%, is, for example, Ca0-AQ OCa
0-CaF CaO-CaF2-23゛2゜AfL OCaO-Al2O2-5in, etc. are listed 2
3' I can get it.

In this way, the skeletal surface layer of a calcium porous material containing 40% or more of CaO easily reacts with oxides such as AiO and SiO2, and therefore absorbs oxides in the molten metal, greatly reducing the amount of oxides present. can be reduced to Further, when CaO is contained in an amount of 40% or more, the stability against C, Ti, and Zr9 is high, so that high-temperature melting of one alloy becomes possible.

The calcia porous material of the present invention only needs to have at least the surface layer of the skeleton made of calcia, and as shown in the cross sections of the skeleton in FIGS.
An aggregate 2 such as mullite is coated with a calcia-containing substance 1 (Fig. 1(a)).

・? ) An aggregate 3 made of metal or the like is coated with a calcia-containing substance 1 (Fig. 1(b)).

(1) An aggregate 4 made of a metal 4a coated with a strong ceramic 4b such as alumina is coated with a calcia-containing substance 1 (Fig. 1 CC,)).

etc. can be adopted.

In order to produce such a calcia% porous body of the present invention, the following steps are carried out in the same manner as the conventional ceramic foam filter material:
A method in which a foamed polyurethane filter material from which the bubble film has been removed is impregnated with a slurry of a calcia-containing substance, and then dried and fired. , ・Φ) A method of applying a calcia-containing substance to the skeleton surface of ceramic, metal, or ceramic-coated metal aggregate (strength member) and baking it can be adopted. In addition, as a method for depositing and baking the calcia-containing substance, a method of applying the calcia-containing substance in the form of a slurry, a method of spraying the calcia-containing substance as a powder, etc. can be adopted.

In the second invention, a molten alloy is brought into contact with a calcia porous body on paper. As a mode of this contact, the porous body may be immersed in the molten metal (or the porous body may be used as a filter medium and the molten alloy may be passed through it; If used as a material, the molten metal will come into good contact with the surface of the porous body skeleton, so the efficiency of removing impurities will be increased.

In the second invention, the molten alloy 1 includes Fe-based,
Those having a Co group or an N1 group can be applied. Among these, it is suitable for application to the case of removing impurities from a Ni-based super-superalloy melt.

In addition, in the invention of gS2, AM may be added to the molten alloy before contacting the molten alloy with the calcia porous body. Reacts with CaO on the surface of the porous body skeleton3
Since calcium aluminate having the desulfurization ability of 'Ca OΦA 203' is produced, it is possible to achieve high purity of the molten metal, particularly a reduction in the oxygen and sulfur contents.

[Function] CaO is Sr generated during melting of Ni-based superalloy.
02, Au2 o3. Oxide inclusions such as HfO2 and the following formula.

S + 02 + Ca O → Ca S r 03 An
203+CaO-CaAu204 Hf O2+ Ca O→Ca Hf O3 A reaction occurs, and these inclusions are chemically adsorbed and removed from the molten metal.

Therefore, if molten alloy is filtered using the porous body of the present invention, it can be filtered by the synergistic action of mechanical and physical filtration action and chemical adsorption and absorption action, and the filtration ability increases. Significantly improved.

The porous body of the present invention can be used not only for filtering molten alloy 1, but also for removing acidic components from gas.

[Examples] The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded.

Example 1, Comparative Example 1 A commercially available spinel ceramic foam filter material (Comparative Example 1), and Ca04 on the skeleton surface of this filter material.
Using a filter material (Example 1) consisting of a porous body of the present invention coated with a calcia-containing substance of 0% or more and baked,
The molten N1 superalloy was filtered.

That is, a molten metal containing 1.0% Hf and 3.0% A was added to a molten Ni-30Cr alloy melted at 1500°C.
, When pouring into a mold, each of the above two types of filter materials is used to filter the molten metal. When the particle size and distribution number of the amount of oxides in the molten metal after the lapse of 30 minutes were investigated, the results were as shown in FIG.

From FIG. 2, it is clear that according to the calcia-based porous material of the present invention, the amount of oxides present in the molten metal obtained by passing through the molten metal is significantly reduced, and the filtration ability is dramatically improved.

In addition, the ceramic foam filter material used (Comparative Example 1
) are as follows.

Material MgOφ A9.203 System Pore size 20 pores/inch Porosity 90% The calcia-containing substance used for adhesion was 1 lime milk slurry (e
5%), this slurry was applied to the porous body at 10%.
The slurry was passed through the porous body at a ratio of 1 cm slurry/1 crn'', dried at 150°C for 2 hours, and calcined at 400°C for XLhr and 900°C for 1hr.

Sintering was performed at 1200°C for 1 hour.

The physical properties of the filter material of the present invention (Example 1) obtained as a result were as follows.

Pore size: 20 pores/inch Porosity: 70% [Effect] As detailed above, the calcia porous material of the present invention has 3
In a porous body having a dimensional network structure, at least the surface layer of the 1st network skeleton contains 40% or more of CaO, and CaO is mixed with oxide inclusions such as An O and HfO. These inclusions can be chemically reacted and adsorbed, and can be efficiently removed from the molten metal.

Therefore, filtration can be performed by the synergistic effect of mechanical and physical filtration effects and chemical adsorption effects, and the filtration ability is greatly improved.

Moreover, since the surface layer of Calusia molluscum has high stability against C, Ti, Zr, etc., the porous body of the present invention can filter even extremely high temperature molten metal.

Furthermore, the calcia-based porous material of the present invention can be easily manufactured by subjecting a conventional filter material to homogeneous adhesion containing cal-6, and is extremely industrially advantageous.

Further, as in the second invention, by bringing one molten alloy into contact with such a calcia porous body, an extremely highly pure alloy can be produced.

[Brief explanation of the drawing]

FIGS. 1(a) to (C) are cross-sectional views of the skeleton to explain the calcia porous material of the present invention, and FIG. 2 is a graph showing the results of filtration experiments according to Example 1 and Comparative Example 1. . 1... Calcia-containing substance, 2.3.4... Aggregate. Agent Patent Attorney Shigeno Warizutsu 1wJ (a) (b) (c) 1: Cal-6-containing homogeneous Figure 2

Claims (4)

[Claims] (1) A calcia-based porous body having a three-dimensional network structure, wherein at least the surface layer of the network skeleton contains 40% or more of CaO. (2) A high-purity alloy comprising a step of bringing a molten alloy into contact with a porous body having a three-dimensional network structure and in which at least the surface layer of the network skeleton contains 40% or more of CaO. Production method. (3) The manufacturing method according to claim 2, wherein the alloy is an Fe-based, Co-based, or Ni-based alloy. (4) Claim 3 or 4, characterized in that Al is added to the molten alloy and then brought into contact with the porous body.
The manufacturing method described in section.