JPS6114064A - Production of ceramic-metal composite body - Google Patents

Abstract

PURPOSE:To improve the wear resistance and heat resistance of a composite body by mounting a cylindrical ceramic molding having specific porosity into a die and rotating the die at a required rotating speed then pouring a molten metal to the inside surface thereof. CONSTITUTION:A ceramic molding 2 having about 2-30mm. wall thickness in mounted via a heat insulating material 6 in the die 5 for centrifugal casting. The molding 2 is formed to 15-50% porosity and the top end thereof is fixed by a band 7 to the die 5. The die 5 is fixed to a turntable 9 and is then rotated at a high speed in such a manner that the G.No. given by D.N<2>/179,000 attains >=200. The molten metal for forming an inside layer 5 is thereafter poured through a spout 8 into the molding 2. The molten metal receives large centrifugal force in the molding 2 and the composite body contg. ceramics at >=50% volumetric ratio is obtd. The wear resistance and heat resistance thereof are thus improved.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for manufacturing a ceramic-metal composite in which a desired metal is completely infiltrated into the pores of a porous ceramic molded body.

<Prior Art> Particles of metal oxides, silicides, nitrides, metal carbides, borides, etc. (hereinafter referred to as ``ceramic particles'') are used as body shell materials for wear-resistant rollers and heat-insulating rollers.

) and metal, and its production methods include placing ceramic particles into molten metal and stirring to ensure uniform dispersion, followed by molding and solidification, and methods that include placing the powder in a container. Examples include a method of filling the container and press-fitting molten metal into the container.

However, not only is it not suitable for industrially producing large products or cylindrical composites, but it also has the drawbacks of low compactness of the ceramic particles and poor abrasion resistance and heat insulation properties.

<Means for Solving the Problems> The present invention was made in view of the above points, and its purpose is to improve the ceramic-metal composite used as the body shell material of wear-resistant rollers and lfT heat rollers. The objective is to provide a method for producing composite bodies with high industrial productivity and a high filling rate of ceramic particles and excellent wear resistance and heat insulation.The technical means for this purpose is centrifugal casting A porous cylindrical ceramic molded body with a porosity of 15 to 50% is placed in a mold, and after rotating the molded body at G No. 200 or more, molten metal is poured into the inner surface of the molded body. The molten metal is allowed to completely penetrate into the pores of the molded body.

Effect> According to the above means, even if the molded body is a low-porosity ceramic molded body having a porosity of 15 to 50%, the molded body can be G N
Since the desired metal is centrifugally cast by centrifugally casting the desired metal by rotating the molded body at a speed of 200° or more, the molten metal can easily and completely penetrate into the pores of the molded body, and it has excellent wear resistance, heat resistance, and A ceramic-metal composite with excellent strength can be easily obtained. Further, by simply increasing the amount of molten metal to be poured as appropriate, it is possible to easily form an inner layer made of cast metal on the inner surface of the permeation layer in which metal has penetrated into the pores of the molded body.

<Example> Next, embodiments of the present invention will be described in detail with reference to the drawings.

First, the ceramic-metal composite which is the object of manufacturing the present invention will be explained.

In FIG. 1, the ceramic-metal composite 1 is composed of a permeation N3 in which a desired metal permeates into a porous cylindrical ceramic molded body 2, and an inner N4 formed on the inner surface of the permeation layer 3. . The cast metal of the inner layer 4 is metallurgically integrally cast with the permeated metal of the permeated layer 3, and the inner layer 4 may not be formed in some cases.

The ceramic molded body 2 is formed by firing ceramic particles, and its materials include Al2O2, ZrO2, Be0
Oxides such as 1Tics SiC, TirCSi3N4, silicides, nitrides, metal carbides, and borides are used. In addition, these ceramic materials have the desired wear resistance, heat insulation (thermal conductivity), wettability with metal, coefficient of thermal expansion,
Selection is made taking into consideration strength, etc.

The porosity of the ceramic molded body 2 is 15 to 50%. As for the porosity, the closer it is to 0%, the better it is without losing the wear resistance and heat insulation properties inherent to ceramics.
In order to form a ceramic-metal composite, it is necessary to have a minimum porosity in order to allow the metal to penetrate into the pores of the ceramic. When the porosity is less than 15%, it is necessary to make the ceramic particles smaller, which inevitably makes the pores smaller, making it difficult for molten metal to penetrate sufficiently, and creating closed pores into which metal cannot penetrate. Therefore, such a part becomes brittle and becomes a quality defect. On the other hand, if it exceeds 50%, the ceramic particle area will be small and the original wear resistance and heat insulation properties will be significantly reduced.

Further, the wall thickness of the ceramic molded body 2 is preferably about 2 mm to 30 fi, although it depends on the diameter of the product. If it is less than 2, the heat insulating effect will be low and the strength will be insufficient, making it difficult to handle. On the other hand, if it exceeds 30, it will be difficult for the molten metal to penetrate throughout the entire range.

The molding method for such a porous ceramic molded body 2 includes a method of mixing 504 to 1.5 W (D ceramic particles with a thermoplastic binder, molding and firing, or a method of mixing 504 to 1.5 W ceramic particles with a thermoplastic binder, or a method of mixing 504 to 1.5 W ceramic particles with a thermoplastic binder, molding and firing, or a method of molding urethane molded into a desired shape). There is a method in which mud-like ceramic fine particles are adsorbed onto a foam, and the ceramic particles are fired and the foam disappears.

The metal material that penetrates the ceramic molded body 2 and forms the inner layer 4 is selected depending on the application, but generally includes high-grade cast iron, Dactino J cast iron, cast steel, other alloy casting materials, and non-ferrous metal casting materials. .

Among these, high-grade cast iron has good penetration into ceramic molded bodies.

Next, a method for producing the above ceramic-metal composite will be described in detail.

As shown in FIG. 2, a ceramic molded body 2 is placed in a vertical centrifugal casting mold 5 via a heat insulating material 6 such as asbestos, and its upper end is fixed with a band 7. Under rotation, the molten metal to be permeated into the pores of the molded body 2 and to form the inner layer 4 is poured into the mold through the pouring gutter 8. During turning, numeral 9 is a turntable, and numeral 10 is a sand mold bottom surface of the mold.

Although FIG. 2 shows an example of vertical centrifugal force casting as the centrifugal force casting means, it is not limited to the vertical type, but can be freely applied to horizontal types, inclined types, etc. Of course, in order to completely infiltrate the molten metal into the ceramic molded body 2 with low porosity, it is necessary to apply a large centrifugal force as described later, but safety is sufficiently ensured and high-speed rotation is easily obtained. From an economic point of view, vertical centrifugal casting is preferred.

When attaching the ceramic molded body 2 to the mold 5, it is preferable to use a heat insulating material 6 such as asbestos. In this way,
This is because the looseness between the ceramic molded body 2 and the mold 5 is eliminated and there is air circulation, so that the molten metal injected into the inner surface of the ceramic easily penetrates into the outer surface.

The ceramic molded body 2 mounted on the mold 5 via the heat insulating material 6 is rotated by 20θ or more at GNO.

G No. is generally expressed as: N: rotational speed (rpm) D: outer diameter of the molded body (shape) The larger the G No., the greater the centrifugal force that acts. When G No. is less than 200 and the porosity of the molded body 2 becomes 50% or less, it becomes difficult for the molten metal to completely penetrate the entire molded body 2, and a large number of independent pores exist. , the strength of that part will be inferior.

When pouring molten metal into the ceramic molded body 2 which is rotated at high speed like a ridge, the molded body 2 must be heated to a temperature of 400 to
It is desirable to preheat to 1200°C.

Such preheating facilitates penetration of the molten metal, prevents cracks in the molded body 2 due to thermal shock caused by casting, and is also effective in preventing cracks due to the difference in shrinkage between the two after casting.

Next, a desired metal melt or hot water is poured into the preheated ceramic molded body 2, and the ceramic-metal composite 1 is obtained.
The thickness can be freely adjusted. That is, if enough molten metal is poured to penetrate into the molded body 2, the inner layer 4 will not be formed, and if more molten metal is poured, the inner layer 4 of the desired thickness will be formed.

The inner layer 4 is suitable for application to rollers, as a highly accurate shaft hole can be easily formed by machining.

Next, specific manufacturing examples will be listed and explained.

Manufacturing example of an outer shell for a heat-insulating and wear-resistant roller with an outer diameter of φ250 x inner diameter of φ200 and a length of 200 uB.

(11 outer diameter φ250 x inner diameter φ200, length 200fi
A molded Al203 ceramic body with a porosity shown in Table 1 was set concentrically in a vertical centrifugal casting mold as shown in Figure 2.At this time, the mold had an inner diameter of φ2
The mold size was 80 mm x length 200 mm, and asbestos was filled between the inner surface of the mold and the outer surface of the molded body.

(2) Place this in the vertical centrifugal force casting 1, and
The ceramic molded body was rotated at the G No. shown in the table, and the ceramic molded body was preheated to a red-hot state with a gas burner before pouring.

Table 1 (3) High grade cast iron 30i+g was poured at a temperature of 1500°C, and after completion of solidification, the mold was balanced at a high temperature and slowly cooled in a heat treatment furnace.

(4) As a result, in both Examples 1 and 2, a high-grade cast iron layer was formed up to the outer surface of the ceramic molded body, and the molten metal penetrated into the entire ceramic molded body, making it completely Al120.
3-A composite of high grade cast iron was obtained.

Note that the cast iron layer formed on the outer surface of the molded body was removed by machining.

A metallographic micrograph (X50) of a cross section of Example 2 is shown in FIG. The microstructure photograph confirms that the cast iron metal completely fills the pores of the ceramic anti-molded body.

<Effects of the Invention> As described above, according to the present invention, the porosity is 15 to 5.
Using a 0% ceramic molded body, a desired molten metal is centrifugally cast into the molded body at a GNo of 200 or more, so the ceramic content exceeds 50% by volume, resulting in excellent wear resistance and heat resistance. It is possible to easily and industrially obtain a high quality ceramic-metal composite having excellent properties and having no unpermeated areas of cast metal. As described above, the present invention has great industrial value as a method for producing a ceramic-metal composite.

[Brief explanation of the drawing]

FIG. 1 shows the ceramics intended for the production method of the present invention.
A vertical cross-sectional view of a metal composite and a ceramic molded body showing the state of the composite before metal infiltration, FIG. 2 is a vertical centrifugal casting machine in the process of manufacturing a ceramic-metal composite by the vertical centrifugal casting method. FIG. 3 shows a metallographic micrograph (50 times magnification) of a ceramic-metal composite of an example of the present invention. DESCRIPTION OF SYMBOLS 1... Ceramic-metal composite, 2... Ceramic molded body, 3... Penetration layer, 4... Inner layer, 5...
Mold for centrifugal force casting, 7... band, 8... pouring gutter. Figure 7 Figure 3

Claims (1)

[Claims] 1. A porous cylindrical ceramic molded body with a porosity of 15 to 50% is placed in a centrifugal casting mold, and the molded body is placed in a G
_N_O_. 2. A method for producing a ceramic-metal composite, which comprises: rotating the molded body at 200 degrees or more, and then pouring molten metal onto the inner surface of the molded body to completely infiltrate the molten metal into the pores of the molded body.