JPS60166156A - Production of ceramic-metal composite material - Google Patents

Abstract

PURPOSE:To apply adequate compressive force to ceramics and to prevent generation of cracking and crazing by disposing a ceramic molding provided with a heat insulating layer on the surface into a metallic mold, preheating the same to the temp. determined by the thickness and porosity of the heat insulating layer and casting a molten metal into the mold. CONSTITUTION:A thermosetting resin such as phenolic resin is coated on the surface of a ceramic molding (having 0.1-2mm. thickness and about 2-85% porosity) to form a heat insulating layer and such molding is disposed in a metallic mold. The molding is preheated to the assigned temp. below the molten metal temp. determined by the thickness and porosity of the heat insulating layer and a molten metal is cast into the mold. The ceramics is free from cracking and crazing in this case and a suitable back pressure is applied to the ceramics by the metallic outside cylinder by which the ceramics is made tough.

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a method for manufacturing a ceramic-metal composite that can be used as a structural part of, for example, automobiles, industrial machines, double-barreled construction machines, etc. It is related to.

(Prior art) Conventionally, as a method for manufacturing this type of ceramic-metal composite by metal casting, a ceramic molded body produced by molding ceramic powder into a predetermined shape and then sintering it is placed in a predetermined position in a mold. There is a method in which the ceramic molded body is surrounded by metal by casting molten metal into the mold after the ceramic mold is set in position.

However, in this manufacturing method, when the molten metal is poured, the high-temperature molten metal comes into direct contact with the ceramic molded body, which may cause a fairly large thermal shock to be applied to the ceramic molded body, causing cracks. There have been problems in that the strength of the ceramic-metal composite may be significantly reduced, and in some cases, the ceramic molded body may be missing.

(Purpose of the Invention) The present invention has been made by focusing on the above-mentioned conventional problems, and has been made to provide a ceramic-metal composite that has excellent mechanical properties without cracking or chipping, especially in the ceramic part. It is an object of the present invention to provide a manufacturing method capable of obtaining a ceramic-metal composite.

(Structure of the Invention) The method for manufacturing a ceramic-metal composite according to the present invention includes: providing a heat insulating layer on the surface of a ceramic molded body;
The present invention is characterized in that the ceramic molded body is set in a mold, and then molten metal is poured into the mold.

In this invention, the ceramic forming the ceramic molded body may be a non-oxide type ceramic such as 5i3N4 (silicon nitride) or silicon carbide (SiC), or alumina (
AfLz 03 ), beryllia (Bed), calcia (Cab), -F gnesia (MgO), silicate (
Si02), ) rear (T h 02), titania (
T t 02 ) + oxide-based materials such as urania (UO2) and zirconia (Z r02 ), as well as mullite (3A cross 203/2S102), spinel (MgOe
Ami 203).

forsterite (2MgO・5i02), zircon (
Zr025si02), Sialon (Si3N4 ・A
There are composite ceramics such as n203), and there are also cermets containing an appropriate amount of metal, and powders appropriately selected from these are used together with binders as necessary to form predetermined shapes such as engines, pumps, injection molding machines, etc. A ceramic molded body is used, which is formed into the shape of a cylinder or cylinder litchi, engine cylinder head port liner, piston head, engine sub-combustion chamber, exhaust manifold liner, etc., and then sintered by firing at a predetermined temperature. .

Further, various metals such as iron or iron alloy, aluminum or aluminum alloy, copper or copper alloy, magnesium or magnesium alloy can be used as the metal in the ceramic-metal composite, and specifically, carbon steel, low alloy steel, manganese steel, nickel steel, cast iron,
Stainless steel, heat-resistant steel, duralumin, sirumin, brass, bronze, Inconel, Nimonik, /＼Stelloy, Stellite, Zircaloy, etc. are used.
Materials with increased wear resistance, heat resistance, etc. (FRM, etc.) are also used.

Furthermore, the heat insulating layer provided on the surface of the ceramic molded body may be a ceramic material constituting the ceramic molded body, a metal material to be cast, or a mixture of these ceramic materials and metal materials. used. In this case, the heat insulating layer should have a low thermal conductivity, and if the porosity is selected appropriately, the thermal conductivity should be low, and the difference in thermal expansion coefficient between it and the ceramic molded body should be small. It is more preferable.

This is preferable in order to prevent the heat insulating layer from cracking or peeling off due to a difference in thermal expansion coefficient when the ceramic molded body is preheated after providing the heat insulating layer on the ceramic molded body.

When providing a heat insulating layer on the surface of a ceramic molded body, there are methods in which the heat insulating layer forming material is thermally sprayed onto the surface of the ceramic molded body using heat such as a plasma arc or an oxygen-acetylene flame, or a method in which the heat insulating layer forming material is coated with phenol resin. A method of immersing a ceramic molded body in a mixed liquid containing a thermosetting resin such as, colloidal silica, lithium silicate, an inorganic binder such as water glass, or applying the mixed liquid to the surface of the ceramic molded body by brushing, spraying, etc. It is possible to adopt methods such as

Further, in some cases, appropriate masking may be applied in order to form a heat insulating layer only on a part of the surface of the ceramic molded body.

The heat insulating layer can be made of ceramics, metal, or cermet as described above, but in the cross-sectional direction of the heat insulating layer, for example, the ceramic molded body side has a large proportion of ceramics (for example, 100%), and the middle part is made of ceramics/cermet. It is a cermet with a varying metal ratio, and the metal side can be a layer with a large metal ratio (for example, 100%).

The thickness of the heat insulating layer described above varies depending on the ceramic molded body, the material of the metal, the casting temperature, the material of the heat insulating layer, the porosity, etc., but is, for example, 0.1 mn+ or more, more preferably 0.2 mn+.
It is more desirable to set it to 55+ma+ or more and 2 fights or less.

The reason for this is that if the thickness of the heat insulating layer is too small, the thermal shock applied to the ceramic molded body during casting of molten metal will be too large, leading to the risk of cracking or chipping of the ceramic molded body.

On the other hand, if the thickness of the heat insulating layer is too large, a thick brittle layer will be formed at the interface of the ceramic-metal composite, which is not desirable.

In addition, the porosity of the heat insulating layer varies depending on the thickness of the heat insulating layer, the material of the ceramic molded body or metal, the casting temperature, etc.
Usually, a range of about 2 to 85% is desirable, and a range of 8% or more is more desirable.

The reason why the porosity of the heat insulating layer is preferably 2% or more, and more preferably 8% or more is because the heat conductivity is lower due to the porous nature of the heat insulating layer. This is because it becomes possible to reduce the heat flux transmitted from the molten metal to the ceramic molded body, and it becomes possible to prevent cracking and chipping of the ceramic molded body. This is because the microcracks generated in the porous structure absorb the sudden thermal stress in the heat insulating layer, thereby preventing the heat insulating layer from peeling off. However, if the porosity becomes excessive, for example greater than 85%, the mechanical strength of the heat insulating layer will decrease, and the strength of the composite, especially the bonding strength and vibration resistance, will decrease. The porous heat insulating layer is easily destroyed by the cooling shrinkage force of the metal after casting, and the metal compression force is not transmitted to the ceramic molded body through the heat insulating layer, so the gap between the ceramic molded body part and the metal part is This is because a strong bond cannot be obtained.

Next, after providing a heat insulating layer on the surface of the ceramic molded body as described above, the ceramic molded body is placed in a mold with Cera I-L, and then the metal selected from among the metals is melted in the mold. A ceramic-metal composite of a predetermined shape is formed by casting molten metal and dismantling the mold after solidification, such as injection molding for engines where the inner circumferential side is made of ceramic material and the outer circumferential side is made of metallic material. Pistons for engines, mud pumps, etc. whose cylinder bodies or piston heads are made of ceramic materials and whose screw parts are made of metal materials, and engine cylinders whose auxiliary combustion chambers are made of ceramics. To obtain a cylinder made of a quality material and a cylinder body of which is made of a metal material, an exhaust manifold lined with a ceramic material, a pipe for transporting a corrosive liquid or mud slurry, etc.

Molds used for casting the above-mentioned metals include gravity casting molds, pressure casting molds (including die casting and molten metal forging),
The mold is appropriately selected from among various molds such as centrifugal casting molds.

When manufacturing the above composite, it is also desirable to preheat the ceramic molded body and the heat insulating layer before casting the molten metal. In this case, there are two methods: preheating the ceramic molded body with a heat insulating layer before setting it in the mold, preheating it together with the mold after setting it, or providing a runner for molten metal near the position where the ceramic molded body is set. It is also possible to adopt a method of preheating using molten metal.

When this preheating was investigated in detail, various experiments revealed that it is more desirable to preheat within the range shown in FIG. 1 (a range above the line corresponding to the porosity of the heat insulating layer). In other words, the larger the thickness of the heat insulating layer and the higher the porosity of the heat insulating layer, the smaller the effect of thermal shock caused by molten metal on the ceramic molded body.
The preheating temperature can be lower than the casting temperature.

By performing preheating within the range shown in Figure 1, damage to the ceramic molded body can be prevented if the heat flow from the molten metal through the heat insulating layer is too large for the ceramic molded body. Become. On this occasion,
The compressive force applied from the metal to the ceramic molded body changes depending on the preheating temperature, which prevents damage to the ceramic molded body.

It is desirable to fully consider the preheating temperature in order to prevent damage or sag of the cast metal. If the preheating temperature is low, the amount of thermal expansion of the ceramic molded body is small, so the portion corresponding to the so-called shrink fit allowance becomes large, and the compressive force on the ceramic molded body becomes excessive when the metal contracts. If the strength of the ceramic is low, it will break, and if the strength of the metal is low, the metal will undergo permanent deformation, making it impossible to obtain the desired composite.

By the way, it has already been known that when casting a ceramic molded body with metal, it is desirable to preheat the ceramic molded body to some extent. However, when a heat insulating layer is provided on a ceramic molded body, the preheating temperature of the ceramic molded body provided with this heat insulating layer (or the preheating temperature of the mold when the ceramic or wood molded body is preheated together with the mold) and the casting temperature of the molten metal. There has been no investigation into the relationship between heat and heat, and if the preheating temperature is too low relative to the thickness of the heat insulating layer, the thermal shock applied to the ceramic molded body will become large and the ceramic molded body will crack. As a result of intensive research, we obtained the relationship shown in Figure 1.

Thus, by preheating the ceramic molded body at a preheating temperature higher than the line shown in FIG. It is possible to prevent the occurrence of cracks and cracks, and at the same time, it is possible to obtain a ceramic-metal composite in which an appropriate compressive force is applied by the metal to the ceramic molded body after solidification of the metal.

(Example 1) As shown in FIG. 2, outer diameter = 30 + lll11. Inner diameter =
The outer circumferential surface of a cylindrical ceramic molded body 1 made of alumina (AuzO3) with a diameter of 25 mm and a length of 30 mm is coated with alumina (Al2O2) powder by plasma melting to have a thickness of 0', 2, 0.4, 0.6
, a heat insulating layer 2 of 0.8 mm was formed. Note that the porosity of the heat insulating layer 2 at this time was in the range of 10 to 15%.

Next, after setting the cylindrical ceramic molded body 1 with the heat insulation layer 2 formed thereon and the cylindrical ceramic molded body 1 without the heat insulation layer 2 formed thereon for comparison into the mold,
Similarly, the ceramic molded body 1 and the mold are preheated to the temperature shown in Table 1, and then molten metal made of 5C313 is cast at a casting temperature of 1600°C, and after solidifying to form the cylindrical metal 3, the ceramic body 1 is poured from the mold. The metal composite 4 was taken out.

Next, the presence or absence of cracks on the ceramic molded body 1 side of the composite body 4 was examined, and the results were also shown in Table 1.

As shown in Table 1, when the heat insulating layer 2 is provided, the ceramic molded body 1 is less likely to crack even when the preheating temperature is lower than when the heat insulating layer 2 is not provided, and the heat insulating layer 2 is made thicker. It became clear that even when the preheating temperature was lowered, cracks could be prevented from occurring in the ceramic molded body 1, and it was found that the results were in good agreement with the results shown in FIG.

(Example 2) As shown in Fig. 2, outer diameter: 30 mm, inner diameter = 25+a
m, length: 30111 m zircon (Zr02-5 i
02) On the outer peripheral surface of the cylindrical ceramic molded body 1,
Similarly, Zirco y (Zr02-5io2) powder (average 1
A 1:1 mixture of 00 mesh) and phenolic resin was applied with a brush and dried at 130°C for 1 hour to form the respective thicknesses of 0.2, 0.4, and 0.0 as shown in Table 2.
．． A heat insulating layer 2 of 6.0.8 mm was formed.

Next, the cylindrical ceramic molded body 1 with the above-mentioned heat insulating layer 2 formed thereon, and the cylindrical ceramic molded body 1 without the heat insulating layer 2 formed thereon for comparison, were each placed in a mold, and then the molded bodies 1 and 2 were placed in the mold, respectively, and the molded bodies 1 and 2 were placed in the mold. The ceramic molded body 1
was preheated together with a mold, and then a molten metal made of 5C3I was cast at a casting temperature of 1600°C, and after solidifying to form a cylindrical metal 3, a ceramic-metal composite 4 was taken out from the mold.

Next, we examined the presence or absence of cracks on the ceramic molded body 1 side of the composite 4, and found that the heat insulating layer 2 was provided as shown in Table 2. In this case, cracks are less likely to occur in the ceramic molded body 1 even when the preheating temperature is lower than when the heat insulation layer 2 is not provided, and the thicker the heat insulation layer 2 is, the more the ceramic molded body 1 is difficult to crack even when the preheating temperature is lowered. It became clear that the occurrence of cracks could be prevented, and it became clear that the results were in good agreement with the results shown in FIG.

(Effects of the Invention) As described above, according to the present invention, after providing a heat insulating layer on the surface of a ceramic molded body, the ceramic molded body is set in a mold, and then molten metal is poured into the mold. By casting, it is possible to prevent problems such as cracks and chips from occurring in the ceramic part of the ceramic-metal composite, and the preheating temperature can be controlled even when preheating the ceramic molded body. It has an extremely excellent effect of improving productivity and quality, and it takes advantage of the characteristics of ceramics, which have excellent heat resistance, corrosion resistance, and abrasion resistance. Composite parts that take advantage of the characteristics of metals, such as excellent mechanical strength and formability, such as cylinders and cylinder litchi for engines, pumps, injection molding machines, engine cylinder head boat liners, sub-combustion chambers, exhaust manifolds, etc.
It has an extremely excellent effect in that piston heads, pipes for transporting corrosive liquids, etc. can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between the thickness of the sprayed layer and the preheating temperature, and FIG. 2 is a perspective view of a composite body manufactured in an example of the present invention. DESCRIPTION OF SYMBOLS 1... Ceramic molded body, 2... Heat insulating layer, 3... Metal, 4... Ceramic-metal system composite. Patent Applicant Daido Steel Co., Ltd. Representative Patent Attorney IM Fung

Claims (5)

[Claims] (1) Production of a ceramic-metal composite, characterized in that after providing a heat insulating layer on the surface of the ceramic molded body, the ceramic molded body is set in a mold, and then molten metal is poured into the mold. Method. (2) The method for manufacturing a ceramic-metal composite according to claim (1), wherein the thickness of the heat insulating layer is 0.1 to 2 mm. (3) The method for producing a ceramic-metal composite according to claim (1) or (2), wherein the heat insulating layer has a porosity of 2 to 85%. (4) Claim (1) in which molten metal is cast after preheating the ceramic molded body and the heat insulating layer.
(2) or (3). (5) The method for manufacturing a ceramic-metal composite according to claim (4), wherein the preheating temperature is in the range of not less than the line shown in FIG. 1 and not more than the casting temperature.