JPH08158002A - Silicon nitride ceramic-metal composite material and parts for molten aluminum - Google Patents

Abstract

PURPOSE: To obtain a composite material maintaining required wear resistance and excellent in corrosion and damage resistances to a molten metal such as a molten Al alloy. CONSTITUTION: Silicon nitride ceramic particles are dispersed by 30-80vol.% in 20-70vol.% Fe-Ni alloy matrix to obtain the objective silicon nitride ceramic- metal composite material. The silicon nitride ceramic particles are preferably spherical particles of <=1,000μm particle size.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a jig for casting a heater tube, a stalk, a thermocouple protection tube, a degassing rotor, a mold, a weir, etc., which is used in contact with a molten metal such as an aluminum alloy. Also, it relates to the most suitable material for molten aluminum parts such as die casting sleeves and plunger chips, which maintains the required wear resistance and has excellent corrosion resistance and damage resistance especially for high temperature molten metal. Regarding composite materials.

[0002]

2. Description of the Related Art Cast iron and hot die steel have been widely used conventionally as constituent members such as heater tubes, molds and weir nests used in the melting and casting process of aluminum alloys. Recently, instead of these iron-based metal members, Ni, M
Engineering such as a hard alloy in which Ni, Mo, W-based compound boride is dispersed in a binder phase composed of o (see, for example, JP-A-2-19441 and JP-A-5-104231) and silicon nitride. It has been proposed to apply materials such as ceramics (for example, JP-A-63-288).
983, Japanese Patent Laid-Open No. 5-77022).

[0003]

The conventional iron-based metal members such as cast iron and hot die steel are easily wet with the molten aluminum alloy melted at about 700 to 800 ° C. and are melted to contaminate the aluminum molten bath. There was a problem of doing. That is, not only is the service life of the member shortened due to melting damage, the replacement frequency is increased and the productivity is reduced, but it is also difficult to ensure the quality of the cast product due to contamination.

On the other hand, ceramic materials are generally hard to wet with molten aluminum, and particularly silicon nitride (Si ₃ N ₄ ) and sialon (Si-Al-O-N ceramics) are
It has the property of being hard to get wet with molten aluminum and less likely to melt. However, since silicon nitride and sialon (hereinafter collectively referred to as silicon nitride ceramics) have lower toughness than iron-based metal materials, there is a problem that they are easily damaged by mechanical impact during use.

Therefore, an object of the present invention is to provide a material which maintains the required wear resistance and is excellent in corrosion resistance and breakage resistance against a molten metal such as an aluminum alloy.

[0006]

The present invention is characterized in that 30 to 80% by volume of silicon nitride ceramic particles are dispersed in a matrix of 20 to 70% by volume of an Fe-Ni-based alloy. And a metal composite material.

In the present invention, the particle size of the silicon nitride ceramic particles is preferably 1000 μm or less, more preferably 300 μm or less. Further, it is desirable that the silicon nitride ceramic particles have a spherical shape. 4a of the periodic table on silicon nitride ceramic particles
A non-oxide conductive material composed of a carbide, boride or nitride of a group 5a group or a group 6a element may be contained in an amount of 30 to 70% by volume. Further, Ti and / or Al are replaced with Fe-Ni.
0.5 to 10% by weight in a Fe-based alloy, Fe-Ni
It is desirable to provide an oxide film on the surface of the system alloy.

The following invention is a composite member in which the composite material of the present invention is joined to another metal body, and the next invention is a part for molten aluminum formed by using the composite material of the present invention.

[0009]

The present inventors pay attention to the property that silicon nitride ceramics are difficult to wet with molten aluminum, and by combining the particles of the ceramics with a metal, it is difficult to wet the molten aluminum and the damage during use is prevented. We considered the development of a fearless material. We made experimental materials by changing the particle size and addition rate of silicon nitride ceramics, and the kind of alloys experimentally and immersing them in a molten aluminum alloy bath to perform corrosion resistance (melting resistance) and damage resistance. We have found a composite material with excellent properties.

First, regarding the alloy serving as the base, Fe-
By using the Ni-based alloy, it is possible to chemically bond with the silicon nitride ceramic particles. The term "chemical bond" as used herein means various atomic bonds other than mechanical bond due to reaction phase formation and the like. The Fe-Ni based alloy is effective for chemical bonding with silicon nitride ceramic particles, and Ni is added to
It is desirable that the content is ˜95% by weight.

In this Fe-Ni alloy, when the Ni content is less than 5% by weight or more than 95% by weight,
The silicon nitride ceramic particles are mechanically bonded and integrated so as to be surrounded by the base alloy, and the silicon nitride ceramic particles do not fall off. In this case, the strength is smaller than that in the case of chemical bonding,
It can be sufficiently applied to members that do not require high strength.

[0012] In addition, Fe, Ni-based alloy, Cr, Mo,
Ordinary Fe or Ni such as Co, C, Si and impurity elements
The alloying element added to or contained in can be contained.

Further, Ti and / or Al may be added to the Fe-Ni type alloy, and it is more preferable to add them. The content of Ti and / or Al is preferably 0.5 to 10% by weight of the Fe-Ni alloy, and can strengthen the bond between the silicon nitride ceramic particles and the matrix metal. If the amount of Ti and / or Al added is less than 0.5% by weight, the effect is small, and even if it is added in excess of 10% by weight, the effect does not increase further.

The amount of silicon nitride ceramic particles dispersed in the Fe-Ni-based alloy serving as a base is preferably 30% by volume or more. If it is less than 30% by volume, it is easily wet with the aluminum alloy and melts easily. The larger the amount of silicon nitride ceramic particles added, the better the erosion resistance, but it is difficult to add more than 80% by volume, and even if it is obtained, it becomes brittle and the damage resistance is considered to be reduced. .

The size of the silicon nitride ceramic particles is 1
It is preferably 000 μm or less. When particles containing more than 1000 μm are contained, due to the difference in coefficient of thermal expansion from the base metal,
Cracks are easily generated in the silicon nitride ceramic particles during the sintering process during manufacturing. Further, 90% or more of the silicon nitride ceramic particles have a size of 10 to 300 μm.
Is more preferably within the range. The strength is higher due to the small number of particles exceeding the size of 300 μm,
By reducing the number of particles of less than m, it is possible to enhance the melt damage resistance to the molten aluminum alloy.

The shape of the silicon nitride ceramic particles is
Although the shape may be angular, if spherical particles are used, the notch effect in strength is reduced and higher strength can be obtained.

By making the silicon nitride ceramic particles contain a non-oxide type conductive material composed of a carbide, boride or nitride of an element of the 4a group, 5a group or 6a group of the periodic table, the electric discharge machining is facilitated. become able to. If the content of the non-oxide conductive material is less than 30% by volume, the electric discharge machinability is not sufficient, and if it exceeds 70% by volume, the original properties of the silicon nitride ceramics are lost.

The composite material of the silicon nitride ceramics and metal of the present invention can completely remove the metal portion from the surface of the member by oxidizing the surface to form an oxide film on the surface of the base Fe-Ni alloy. Therefore, it is possible to impart more excellent erosion resistance to the molten aluminum alloy. If the silicon nitride ceramics is also oxidized under such conditions, the entire surface can be covered with an oxide film. In this case, more excellent melting resistance can be imparted.

In the composite material of silicon nitride ceramics and metal of the present invention, since the matrix is a metal, the metal portion serves as a bonding surface and can be easily bonded to another metal member. As a joining method, a brazing method, a diffusion joining method, an integral sintering method using a hot press or a hot isostatic press (HIP), etc. can be applied.

[0020]

【Example】

Example 1 Sialon and Si ₃ N ₄ were prepared as silicon nitride ceramic particles. Spherical particles were obtained by producing granules by a spray dry method and sintering the granules in nitrogen gas. In addition to this, for Sialon, crushed sintered blocks were also used to create angular particles. These silicon nitride ceramic particles are passed through a sieve to
5 μm or less and partly 1000 μm or less, 1200 μm
Adjusted below. On the other hand, spherical particles having an average particle diameter of 30 μm and having 7 different compositions were prepared as Fe—Ni based alloys. These silicon nitride ceramic particles and Fe-N
i-based alloy and silicon nitride ceramic particles 20 to 8
0% by volume, and 80 to 2% Fe-Ni based alloy correspondingly
Mixed at a ratio of 0% by volume. The obtained mixed powder was filled in a cylindrical container made of mild steel, deaerated under vacuum, and then 1200 ° C, 1
HIP treatment was performed under the conditions of 00 MPa and 4 hours. After cooling, each sample was cut and the cross section was observed with an optical microscope. As a result, there was no gap at the interface between the silicon nitride ceramic particles and the Fe—Ni alloy, and a dense sintered body was obtained.

10 × 10 × 70 mm from these sintered bodies
JIS A that was cut out from the test piece and heated and melted at 800 ° C
After soaking in a DC12 aluminum alloy bath for 24 hours,
I pulled it up from the bath. After the aluminum alloy attached to the test piece was dissolved and removed with an acid, the dimensions of the test piece were measured to measure the melt loss thickness. Also, 15 x 15 x 5 m thick from the sintered body
A test piece of m was cut out, the test piece was placed on a steel plate, and a steel ball having a diameter of 20 mm was naturally dropped from a height of 3 m to collide with the steel ball, and the presence or absence of cracks was investigated. Furthermore, from the sintered body 3
A 4 × 40 mm test piece was cut out and the 4-point bending strength was measured according to the JIS method.

In addition to the above, conventional materials such as cast iron (flake graphite cast iron), hot die steel (SKD61) and sialon were prepared and the same test was conducted for comparison.

Tables 1 and 2 show the conditions for producing the test pieces described above. Tables 3 and 4 show the test results of the test pieces. The contents will be described below. No. 1
Examples 3 to 3 contain 30, 55 and 80% by volume of spherical sialon particles having a particle size of 295 μm or less, in contrast to F
53% Fe-with an average particle size of 30 μm as an e-Ni alloy
It is a material obtained by adding and mixing 30% Ni-17% Co alloys at 70, 45 and 20% by volume, and HIP sintering. Among these materials, the larger the amount of sialon added, the smaller the melt loss thickness and the better. Compared with cast iron and hot die steel, which are comparative materials of Nos. 17 and 18, the melt loss thickness was about 35% or less, and excellent melt loss resistance was obtained.

No. 4-5 examples have a particle size of 100
The spherical sialon particles of 0 m or less were added in an amount of 30% by volume, and Fe-Ni alloys were each 95% Fe-5% N.
i is a material obtained by adding and mixing 70% by volume of 5% Fe-95% Ni alloy and HIP sintering. No. Examples 6-9 are:
The amount of spherical sialon particles having a particle size of 295 μm or less was fixed at 55% by volume, and Fe—Ni-based alloy was used as Fe—
Ni-Cr, Fe-Ni-Ti, Fe-Ni-Co-T
It is a material obtained by adding and mixing 45% by volume of each alloy of i and Fe-Ni-Co-Ti-Al and HIP sintering. All of these materials have a small melt loss thickness and are good. 1
Compared to the cast iron and hot die steel Nos. 7 and 18, the melt loss thickness was about 17% or less, and excellent melt loss resistance was obtained.

No. 10 examples have a particle size of 295μ
The amount of square sialon particles having a particle size of m or less is set to 55% by volume, and as an Fe-Ni alloy, 53% Fe-30% Ni-
It is a material obtained by adding and mixing 45% by volume of 17% Co alloy and HIP sintering. This material is a comparative material No. 17, 18
In comparison with the cast iron and hot die steel, the erosion resistance was about 14%, and excellent erosion resistance was obtained.

No. Eleven examples have a particle size of 295μ
The amount of spherical Si ₃ N ₄ particles of m or less is set to 55% by volume,
53% Fe-30% Ni-17 as Fe-Ni alloy
% Co alloy is added and mixed in an amount of 45% by volume and HIP sintered. This material is a comparative material No. Compared with the cast iron and hot die steel Nos. 17 and 18, the melt loss thickness was about 12%, and excellent melt loss resistance was obtained.

No. The examples of Nos. 12, 13 and 14 are Nos. After HIP treatment in the same manner as in Examples 1, 2, and 3, the cut test piece was heated in the atmosphere at 900 ° C. for 1 hour to oxidize the surface. No melt damage was observed in these materials, and high melt damage resistance was exhibited. In FIG. 3, N
o. The schematic cross section which provided the oxide film on the surface of the 12 test piece is shown. In FIG. 3, oxide film 4 formed on surface 3
Is wedge-shaped between the matrix 5 (Fe-Ni alloy) and the sialon particles 6, and is unlikely to peel off from the surface 3.

As described above, No. In each of Examples 1 to 14, the No. 1 has no melt-thickness and a good melt-loss resistance, and cracks did not occur even in the steel ball drop test. 1
Sialon of Comparative Material No. 9 was good in comparison with cracking. No. The bending strengths of the materials in Examples 1 to 14 were 190 MPa or more. This is a comparative example No. The strength was equal to or higher than that of the cast iron No. 17, and practically sufficient strength was obtained. The bending strength showed a higher value as the material containing less silicon nitride ceramic particles was added. Further, higher bending strength was obtained with a material in which Ti or Al was added to the Fe-Ni based alloy.

No. In Comparative Example No. 15, since the size of the sialon particles contained large particles up to 1200 μm, cracks occurred in the sialon particles and the Fe—Ni-based alloy in the sintered body, so that the bending strength was as low as 108 MPa. There wasn't.

No. In the comparative example of No. 16, the addition amount of sialon particles was as small as 20% by volume, and therefore the melt loss thickness was as large as 1.2 mm. Only the same erosion resistance as that of cast iron 17 or 18 or hot die steel was obtained.

[0031]

[Table 1]

[0032]

[Table 2]

[0033]

[Table 3]

[0034]

[Table 4]

(Embodiment 2) Next, an embodiment in which the above-mentioned composite material of silicon nitride ceramics and metal is joined to another metal body will be described. FIG. 1 shows a hollow cylindrical composite member as an example. In this hollow cylinder, the inner material 1 is the composite material of the silicon nitride ceramics of the present invention and a metal, and the outer material 2
Is formed of steel or the like, and the interface between the two is chemically bonded.
This composite is characterized in that it can be applied to a wider range of jigs, parts, and devices because the inner material 1 having a cylindrical surface has excellent erosion resistance and the outer material 2 has higher strength and toughness. .

This hollow cylindrical composite member was produced by the following method. That is, JIS STKM (0.25% of outer material 2
(C carbon steel) A cylindrical container made of JIS SUS304 stainless steel, the surface of which was coated with a release agent, was set in the center of the cylindrical container, and the space between them was filled with Example No. 1 in Table 1. 55% by volume of spherical sialon particles having a particle size of 295 μm or less shown in 2
And a mixed powder of the inner material 1 consisting of 45% by volume of metal particles having a composition of 53% Fe-30% Ni-17% Co alloy and having an average particle diameter of 10 μm, and the airtight sealing after vacuum deaeration of the cylindrical container. Then, HIP was performed under the conditions of 1150 ° C., 100 MPa, and 2 hours. After cooling, both ends of the cylindrical body were cut, and the stainless steel round bar set at the center was pulled out. As a result, a composite member including the inner member 1 and the outer member 2 shown in FIG. 1 could be manufactured. FIG. 2 shows a photograph of the metallographic structure of the joint interface between the inner member 1 and the outer member 2 of this composite member.

(Embodiment 3) FIG. 4 is a vertical cross-sectional view of a casting weir insert made of a composite material of silicon nitride ceramics and a metal, which is an embodiment of the present invention. Ti with sialon
50% by volume of spherical conductive sialon particles having a particle size of 295 μm or less containing 40% by volume of N and having an average particle size of 30
A material obtained by adding and mixing 50% by volume of 74% Fe-8% Ni-18% Cr alloy of μm was HIP sintered. By subjecting this sintered body to electric discharge machining, the outer diameter A is 65 mm, as shown in FIG.
Height B is 50 mm, hollow inner diameters C and D are 45 each
It processed into the shape of the weir insert 7 of 37 mm and 37 mm. Then, this sintered body was heated in the atmosphere at 900 ° C. for 1 hour to oxidize the surface.

Further, as a casting weir of another embodiment of the present invention, a structure in which a composite material of silicon nitride ceramics and a metal is joined to another metal body may be used as described in the second embodiment. That is, as shown in FIG. 5, the inner material 8 that directly contacts the molten metal may be formed of a composite material of the silicon nitride ceramics of the present invention and a metal, and the outer material 9 may be formed of crude steel or the like.

When the weir insert 7 constructed as described above was fitted in a mold (not shown) and low pressure casting was carried out with a molten aluminum alloy, it was 200 in the case of a conventional hot die steel weir insert. The weir insert of the present invention is 500 times as compared with the case where replacement is required due to melting damage after using ~ 300 shots.
It was possible to continuously use 0 shots or more, and it was possible to confirm about 20 times or more melting resistance.

(Embodiment 4) FIG. 6 is a vertical cross-sectional view of a die casting sleeve made of a composite material of silicon nitride ceramics and a metal, which is an embodiment of the present invention. In FIG. 6, a die casting sleeve 10 is provided in a metal outer cylinder 11 (outer diameter 130 mm, inner diameter 90 mm, length 400 mm).
An inner cylinder 12 (outer diameter 90 mm, inner diameter 60 mm, length 400 mm) made of the composite material of the present invention was shrink-fitted and fixed at a temperature of 550 to 600 ° C. 13 is die casting sleeve 1
It is a molten metal injection port opened near the end of No. 0. Inner cylinder 12
Is 50 volume% of conductive sialon particles having a particle size of 295 μm or less obtained by adding 40 volume% of TiN to sialon.
And 53% Fe-30% Ni-17 having an average particle size of 10 μm
A material obtained by adding and mixing 50% by volume of a% Co alloy was HIP-sintered and then subjected to finishing processing. Further, as described in the second embodiment, the die-casting sleeve of the present invention includes the inner cylinder 12 made of the composite material of the present invention and the outer cylinder 11 made of metal or the like,
They may be integrally joined by IP sintering.

The die-casting sleeve configured as described above was mounted on an injection device of a horizontal die-casting machine having a mold clamping force of 350 ton and used for die-casting of aluminum alloy. As a result, compared with the conventional die-casting sleeve made of hot die steel, it was necessary to replace the die-casting sleeve of the present invention due to melting damage at injection of about 10,000 shots.
Stable injection of 0000 shots or more was able to be performed, and about 10 times or more of melt damage resistance could be confirmed.

[0042]

As described above in detail, according to the present invention, it is possible to greatly improve the erosion resistance and the breakage resistance of the materials which have hitherto been insufficient. Therefore, various materials used in contact with a molten aluminum alloy are used. The life and reliability of parts can be significantly increased.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a hollow cylindrical composite member according to an embodiment of the present invention.

FIG. 2 is a photograph of the metallographic structure of the joint interface of the hollow cylindrical composite member of the example of the present invention.

FIG. 3 is a schematic cross-sectional view in which an oxide film is provided on the surface of the composite material of the present invention.

FIG. 4 is a vertical cross-sectional view of a casting dam according to an embodiment of the present invention.

FIG. 5 is a vertical sectional view of a casting dam according to another embodiment of the present invention.

FIG. 6 is a vertical sectional view of a die casting sleeve according to an embodiment of the present invention.

[Explanation of symbols]

1 inner material, 2 outer material, 3 surface, 4 oxide film, 5 base, 6 sialon particles, 7 weir nest, 8 inner material, 9 outer material, 10 die casting sleeve, 11 outer cylinder, 12 inner cylinder, 13 molten metal injection port

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Shigeyuki Hamayoshi 1-9-1 Kitahama, Wakamatsu-ku, Kitakyushu City Hitachi Metals Co., Ltd. Wakamatsu Factory (72) Inventor Toshio Okitsu 1-9-1, Kitahama, Wakamatsu-ku, Kitakyushu Hitachi Metals Co., Ltd. Wakamatsu Factory

Claims (10)

[Claims] 1. Silicon nitride ceramic particles 30 to 8
A composite material of silicon nitride ceramics and a metal, characterized in that 0% by volume is dispersed in a matrix of an Fe-Ni alloy of 20 to 70% by volume. 2. The composite material of silicon nitride ceramics and a metal according to claim 1, wherein the silicon nitride ceramic particles have a particle size of 1000 μm or less. 3. The composite material of silicon nitride ceramics and a metal according to claim 1, wherein the silicon nitride ceramic particles have a particle size of 300 μm or less. 4. The composite material of silicon nitride ceramics and metal according to claim 1, wherein the silicon nitride ceramic particles are spherical. 5. A non-oxide conductive material made of a carbide, boride or nitride of an element of 4a group, 5a group or 6a group of the periodic table in silicon nitride ceramic particles. Item 7. A composite material of the silicon nitride ceramics and a metal according to any one of Items 1 to 4. 6. The silicon nitride ceramic and the metal according to claim 1, wherein the silicon nitride ceramic particles contain a non-oxide conductive material in an amount of 30 to 70% by volume. Composite material. 7. The silicon nitride ceramics and metal according to any one of claims 1 to 6, characterized in that Ti and / or Al is contained in an Fe-Ni based alloy in an amount of 0.5 to 10% by weight. Composite material. 8. The composite material of silicon nitride ceramics and a metal according to claim 1, wherein an oxide film is provided on the surface of the Fe—Ni alloy. 9. A composite member, characterized in that the composite material according to any one of claims 1 to 8 is bonded to another metal body. 10. A component for molten aluminum, comprising the composite material according to any one of claims 1 to 9 as a constituent member.