JP2002205158A - Cast joined body and its producing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cast joined body and its producing method with which wear resistance, heat resistance, rigidity and also, corrosion resistance can be improved while utilizing the light-weight of a Mg alloy. SOLUTION: The cast joined body is composed by joining a member to be cast composed of a Fe alloy, a Ni alloy or a Cu alloy and a cast member composed of a Mg alloy by interposing an electrical insulating layer on the interface between the both members. This producing method is performed as the followings. (1) After forming a film composed of material forming the electrical insulating layer on a part of or on the whole surface of the member to be cast by reacting with molten Mg alloy, the member to be cast, this is cast with the Mg alloy. (2) After forming the electrical insulting layer composed of an oxide on the surface by heating the member to be cast, the member to be cast, is cast with the Mg alloy. As the other embodiment, in the method for cast the member to be cast, which is composed of an Al alloy or an Al base composite material with the cast member composed of the Mg alloy, after forming the film composed of material reacting with the molten Mg alloy on a part of or on the whole surface of the member to be cast, the member to be cast, this is cast with the Mg alloy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a Mg alloy member,
F with better heat resistance, wear resistance, rigidity and corrosion resistance than Mg
The present invention relates to a cast-in joined body in which an e-alloy, a Ni alloy, a Cu alloy, an Al alloy or an Al-based composite material is joined by cast-in and integrated, and a method for producing the same.

[0002]

2. Description of the Related Art Mg alloys are being studied for application to automobile parts by taking advantage of their light weight. However, for example, the Mg alloy is not sufficient for application to a part requiring heat resistance, wear resistance, rigidity, and corrosion resistance at high temperatures, such as a cylinder part of an engine block.

[0003] Therefore, development of a metal matrix composite material in which an Mg alloy matrix is reinforced with ceramic particles or fibers has been promoted. However, although the heat resistance, abrasion resistance, and rigidity are improved by using a composite material, the corrosion resistance cannot be improved. For example, in the case of an engine block made of an Mg alloy, it is conceivable that a cylinder liner is made of cast iron, an Al alloy, or an Al-based composite material, and the Mg alloy is cast in order to increase the corrosion resistance of the cylinder portion. However, in this case, electric corrosion occurs due to the contact between the cast iron and the Mg alloy, thereby deteriorating the corrosion resistance, or a brittle Al-Mg intermetallic compound (Al ₁₂ Mg) is formed on the joint surface between the Mg alloy and the Al alloy. ₁₇ , Al ₃ Mg ₂ ) is generated, and there is a problem in that the joint strength is reduced due to the occurrence of cracks at the joint surface.

[0004] Alternatively, after machining the inner surface of the Mg alloy cylinder, a liner of cast iron, an Al alloy or an Al-based composite material may be driven. However, since the inner surface of the cylinder portion and the liner are merely in close mechanical contact with each other, there is a problem that heat conduction for cooling becomes insufficient.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a cast-in joint capable of improving the wear resistance, heat resistance, rigidity and corrosion resistance while utilizing the lightness of an Mg alloy, and a method for producing the same. With the goal.

[0006]

According to a first aspect of the present invention, there is provided a cast-in member made of an Fe alloy, a Ni alloy or a Cu alloy, and a cast-in member made of a Mg alloy. However, there is provided a cast-in joined body characterized in that it is joined to both interfaces with an electric insulating layer interposed therebetween.

Typically, the above-mentioned electric insulating layer is made of ceramics. As this ceramic, Al ₂ O ₃ ,
SiO ₂ , ZnO, 2MgO · SiO ₂ , MgO · SiO
₂ , ZrO ₂ · SiO ₂ , 2MgO · 2Al ₂ O ₃ · 5Si
_{O 2, 3Al 2 O 3 ·} 2SiO 2, TiO 2, Si 3 N consists of _four may be used one or more selected from the group.

In a first method for producing a cast-in joined body according to the first invention, the electric insulating layer is formed on a part or all of the surface of the cast-in member by reacting with the molten Mg alloy. It is characterized in that after forming a film made of a substance, it is cast-in with the above Mg alloy. When the above reaction is an exothermic reaction, it becomes easy to maintain the molten Mg alloy at a high temperature on the surface of the cast-in member, which is advantageous in increasing the bonding strength.

The above-mentioned film can be formed by plating or thermal spraying. The material of this film is Al
₂ O ₃ , SiO ₂ , ZnO, 2MgO.SiO ₂ , MgO.
_{SiO 2, ZrO 2 · SiO 2} , 2MgO · 2Al 2 O 3 ·
_{5SiO 2, 3Al 2 O 3 ·} 2SiO 2, TiO 2, Si 3 N
One or more selected from the group consisting of ₄ can be used.

[0010] A second method of manufacturing a cast-in joined body according to the first invention is to form the electric insulating layer made of oxide on the surface of the cast-in member by heating the member. It is characterized by being cast in an alloy. Furthermore,
In order to achieve the object of the present invention, according to the second invention, A
a cast-in member made of an alloy or an Al-based composite material,
A method of casting with a cast-in member made of a Mg alloy, and after forming a film made of a material that reacts with a molten metal of the Mg alloy on a part or all of the surface of the cast-in member,
A method for producing a cast-in joined body, characterized by being cast-in with the Mg alloy, is provided.

In the method according to the second aspect of the present invention, if the reaction is an exothermic reaction, it becomes easy to maintain the molten Mg alloy at a high temperature on the surface of the cast-in member, which is advantageous in increasing the bonding strength. is there. Further, the above-mentioned film can be formed by plating or thermal spraying. As the substance forming the above-mentioned film, Si, Ni, Cu, Zn, Sr, Tl,
A substance selected from the group consisting of Sb or SiO ₂ ,
A substance selected from the group consisting of Al ₂ O ₃ and Fe ₂ O ₃ can be used.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the first invention, an electric insulating layer is interposed at an interface between an Fe alloy, a Ni alloy or a Cu alloy, which is a cast-in member, and an Mg alloy, which is a cast-in member. While preventing the occurrence of electrolytic corrosion due to contact with
The high heat resistance, abrasion resistance, rigidity, and corrosion resistance of Fe alloy, Ni alloy, and Cu alloy can be imparted to the required portions of the Mg alloy member.

In the second aspect of the present invention, since a film of a material that reacts with the molten Mg alloy is provided on the surface of Al or an Al-based composite material, which is a cast-in member, the molten Mg alloy and the material of the film are mixed during casting. Reacts with each other to suppress generation of a brittle Al-Mg intermetallic compound due to the reaction between the molten Mg alloy and Al, and can provide high corrosion resistance due to Al while securing high bonding strength.

The electric insulating layer according to the first invention can be generally formed of ceramics. However, some ceramics are not suitable as an electrical insulating layer.
For _{example, FeO, Fe 3 O 4,} Cu 2 O, Ti 2 O 5, Si
C or the like does not become an electric insulating layer, and the effect of preventing electrolytic corrosion cannot be obtained. In connection with the second invention, Japanese Patent Application Laid-Open No. 1-289560 discloses that a cast-in member made of an Al alloy or an Al-based composite material is adhered to the surface of a cast-in member when casting with a molten Mg alloy. A method is disclosed in which after an oxide film on the surface is removed with potassium zirconium fluoride or potassium aluminum fluoride, the film is brought into contact with a molten Sn alloy to form a Sn alloy coating, and then cast with a molten Mg alloy. In this method, the Sn alloy film merely melts and diffuses in the molten Mg alloy, and does not react with the molten Mg alloy unlike the second invention of the present application. The formation reaction of the compound cannot be prevented, and the above-mentioned effects according to the second invention of the present application cannot be obtained.

In the present invention, the Mg alloy used for cast-in may be any Mg alloy commonly used for casting. Representatively, a large number are specified in ASTM standards, JIS standards, and the like, and Mg-Al-Mn alloys (ASTM A
M100A), Mg-Al-Zn-Mn alloy (A
Z63A, etc.), Mg-Al-Si-Mn alloys (AS
41A etc.), Mg-Al-RE-Mn alloys (AE4
2), Mg-Zn-Zr alloy (ZK51A etc.),
Mg-RE-Zn-Zr alloy (e.g., EZ33A), M
g-Ag-RE-Zr alloy (QE22A etc.), Mg
-Zn-Cu-Mn alloy (ZC63A etc.), Mg-
Y-RE-Zr alloys (WE54E etc.) are included.

[0016]

[Embodiment 1] An engine block made of an Mg alloy in which the first invention was applied to a cylinder portion was manufactured. FIG. 1 schematically shows a part of the cross section. The engine block main body 1 is made of an Mg alloy in order to reduce the weight as a whole, and the cylinder portion 2 which needs to be improved in heat resistance, wear resistance, rigidity and corrosion resistance is made of cast iron. An electrical insulating layer 3 is interposed at the joint interface between the two, preventing electrical contact between the two and preventing electrolytic corrosion.

The procedure for manufacturing the engine block of FIG. 1 is as follows. First, the cylinder part 2 is cast with cast iron (JIS FC250). Next, only the portion that becomes the joining interface of the cylinder portion 2 is sprayed with alumina (Al
₂ O ₃ ) A film (0.5 mm thick) of particles is formed. next,
The cylinder part 2 on which the above-mentioned film is formed is placed in a mold, and M
The molten metal of the g alloy (AS41A) is cast into a mold by pouring. Fig. 1
Engine block is obtained.

[Embodiment 2] An engine block made of an Mg alloy in which the first invention was applied to a cylinder portion was manufactured. FIG. 2 schematically shows a part of the cross section. In Example 1, the entire cylinder portion 2 was made of cast iron. In Example 2, however, only the liner portion 2a of the cylinder portion 2 was made of cast iron. An electrical insulating layer 3 is interposed at the joint interface between the engine block main body 1 and the cylinder liner portion 2a to prevent electrical contact between the two and prevent electrolytic corrosion.

The procedure for manufacturing the engine block of FIG. 2 is as follows. First, a cylindrical cylinder liner member 2a is cast from cast iron (FC250). Next, only the outer peripheral surface of the cylinder liner member 2a is sprayed with a mullite (3Al ₂ O ₃ .2SiO ₂ ) particle coating (0.5 m thick).
m). Next, the cylinder liner member 2a on which the film is formed is placed in a mold, and a Mg alloy (AZ91
The molten metal of D) is cast into a mold by pouring into the mold. The engine block shown in FIG. 2 is obtained by removing from the mold after solidification.

[Embodiment 3] An engine block made of a Mg alloy in which the second invention was applied to a cylinder portion was manufactured. FIG. 3 schematically shows a part of the cross section. The engine block body 1 is made of an Mg alloy and the cylinder body 2 is made of an Al alloy in order to reduce the overall weight. The cylinder liner portion 2a that needs to be improved in heat resistance, wear resistance, rigidity, and corrosion resistance is It is made of an Al-based composite material. No crack is observed at the joint interface between the engine block main body 1 and the cylinder part main body 2, and good joining is performed via the reaction layer 4 with the coating layer.

The procedure for manufacturing the engine block of FIG. 3 is as follows. Crystalline alumina having an average diameter of 25 μm
Silica short fibers _{(48% Al 2 O 3 -52} % SiO 2, trade name Alsilon) 5% and, mullite particles having an average particle diameter of _{12μm (3Al 2 O 3 · 2SiO} 2) outer diameter 86 mm × inner diameter 76mm made of 10% × After preheating a cylindrical forming body having a height of 85 mm, the inside of the formed body is impregnated with a molten aluminum alloy (ADC12 according to JIS) by high-pressure casting, and a cylinder part 2 having an Al-based composite material liner part (cylinder part 2a) on the inner surface is formed. obtain. The resulting cylinder surface is coated with a mixture of SiO ₂ particles and Ni particles by 0.5 mm by thermal spraying. After the members are preheated, they are placed in an engine block mold, and are cast-in while producing a reaction layer 4 between a molten Mg alloy (ASTM standard AS41A) and a coating layer by die casting to produce an engine block.

[0022]

According to the present invention, there is provided a cast-in joint which can improve the corrosion resistance as well as the wear resistance, heat resistance and rigidity while utilizing the lightness of the Mg alloy, and a method for producing the same.

[Brief description of the drawings]

FIG. 1 is a partial sectional view showing an example of an engine block according to a first invention.

FIG. 2 is a partial cross-sectional view showing another example of the engine block according to the first invention.

FIG. 3 is a partial sectional view showing an example of an engine block according to a second invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Engine block main body 2 ... Cylinder part 2a ... Liner part of a cylinder part 3 ... Electrical insulation layer 4 ... Reaction layer

Claims (13)

[Claims] 1. A cast-in member made of an Fe alloy, a Ni alloy or a Cu alloy, and a cast-in member made of a Mg alloy, which are joined to each other with an electric insulating layer interposed therebetween. Cast-in joint. 2. The cast-in joined body according to claim 1, wherein the electric insulating layer is made of ceramics. 3. The method according to claim ₂ , wherein the ceramic is Al ₂ O ₃ , SiO _{2
2, ZnO, 2MgO · SiO 2} , MgO · SiO 2, Z
_{rO 2 · SiO 2, 2MgO ·} 2Al 2 O 3 · 5SiO 2,
_{3Al 2 O 3 · 2SiO 2,} TiO 2, Si 3 N 4 to consist of one or more selected from the group consisting of and wherein claim 2 cast assembly according. 4. The method for manufacturing a cast-in joined body according to claim 1, wherein a part or all of the surface of the cast-in member reacts with the molten metal of the Mg alloy to form the electrical insulating layer. A method for producing a cast-in joint, comprising: forming a film made of a substance to be formed; 5. The method according to claim 4, wherein the reaction is an exothermic reaction. 6. The method according to claim 4, wherein the coating is formed by plating or thermal spraying. 7. The method of claim 4, wherein the coating
Substance is Al_TwoO_Three, SiO_Two, ZnO, 2MgO.Si
O_Two, MgO / SiO_Two, ZrO_Two・ SiO_Two, 2MgO ・
2Al_TwoO_Three・ 5SiO_Two, 3Al_TwoO_Three・ 2SiO_Two, Ti
O_Two, Si_ThreeN _FourFrom one or more selected from the group consisting of
A method for producing a cast-in joined body, characterized by comprising: 8. The method for manufacturing a cast-in joined body according to claim 1, wherein the electrically insulating layer made of an oxide is formed on a surface of the cast-in member by heating the member. A method for producing a cast-in joined body, characterized by casting with the Mg alloy. 9. A method for casting a cast-in member made of an Al alloy or an Al-based composite material with a cast-in member made of an Mg alloy, wherein a part or the whole of the surface of the cast-in member is provided with A method for manufacturing a cast-in joined body, comprising: forming a film made of a substance that reacts with a molten Mg alloy; 10. The method according to claim 9, wherein the reaction is an exothermic reaction. 11. The method according to claim 9, wherein the coating is formed by plating or thermal spraying. 12. The method according to claim 9, wherein the substance forming the film is Si, Ni, Cu, Zn, Sr,
A method for manufacturing a cast-in bonded body, wherein the method is selected from the group consisting of Tl and Sb. 13. The method of claim 9, wherein the material forming the film is selected from the group consisting of SiO ₂ , Al ₂ O ₃ , and Fe ₂ O ₃ . Production method.