JPH084896B2 - Method for manufacturing ceramic-metal composite - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention mainly relates to a method for producing a cylindrical ceramic-metal composite used as a shell outer shell material of a wear-resistant roll.

(Prior Art) A composite of metal oxide particles, silicon nitride, nitride, boride, carbide particles (hereinafter referred to as ceramic particles) and metal is used as the outer shell material of the wear-resistant roll. Has been.

Conventionally, such a composite has been formed by a method in which a mixture of ceramic particles and a metal powder is directly overlaid as molten metal on a roll surface by a plasma overlaying method.

(Problems to be Solved) In manufacturing the above-mentioned build-up roll, the work must be performed by moving the plasma torch in the axial direction of the roll while rotating the roll, and the productivity is low.

In particular, low productivity is a problem when manufacturing large-diameter and long rolls.

Further, when the mixing ratio of the ceramics of the overlay metal is 10% or more, the cracking susceptibility of the overlay layer becomes high, so that a considerably high residual heat temperature is required, and heat management is difficult because it involves high heating work.

Further, since the solid base material is coated with hot metal, the relative value between the shrinkage when the molten metal is exposed to the atmosphere and rapidly cooled and the shrinkage of the base material causes the build-up layer to be pulled at room temperature, or The residual stress of compression remains, and the problem of strain generation after cooling is large.

Further, the build-up method coats the base material so that adjacent beads are slightly overlapped with each other, and there is a slight difference in the characteristics between the overlapped portion and the non-overlapped portion of the bead, so that the roll surface is made uniform. It was not possible to finish it in the characteristic.

(Means for Solving Problems) The present invention clarifies a method for producing a ceramic-metal composite by taking advantage of the fact that the centrifugal casting method has a high production method and little product distortion occurs. is there.

The method for producing the Serramix / metal composite of the present invention is to mix droplets of ceramics and metal melted by high heat of plasma arc into a metal melt which is a casting material, and solidify the mixed melt under centrifugation. Characterize.

(Operation and effect) A ceramic-metal composite can be efficiently produced by a highly productive centrifugal casting method, especially in the production of large diameter and long products.
The manufacturing efficiency is significantly improved as compared with the case where the wear resistant layer is formed by the conventional plasma overlay method.

It is considered that ceramics have substantially no melting point, and because the specific gravity is light, it is impossible to melt only ceramics by a plasma arc and mix them with the molten metal, and the ceramics are not sufficiently dispersed in the molten metal.

However, as in the present invention, it is possible to mix the ceramics well with the molten metal by injecting the droplets in which the ceramics and the metal are mixed together into the molten metal which is the centrifugal casting material.

Further, by casting under centrifugal force, the ceramics solidify in a uniform distribution in the axial direction and the circumferential direction of the roll, so that the outer circumference of the roll can be formed with uniform quality.

Since it is cast molding, there is an advantage that distortion is less likely to occur as compared with the conventional case where a solid base material is coated with high temperature molten metal.

(Embodiment) FIG. 1 shows a centrifugal casting apparatus used for carrying out the present invention, in which a centrifugal casting mold (1) is installed on a rotating roller (3) and annular molds are provided at both ends of the mold. Hot water band (2)
(2) is installed.

Injection gutter (4) through the central hole (21) of one of the water stop bands
Insert the tip of the into the mold.

The injection trough (4) has a first intake port (41) at the outer end and a second intake port (42) on the mold side from the first intake port.

A plasma arc generating torch (5) is disposed above the second inlet (42) of the injection trough (4) toward the inlet, and the torch (5) is provided with a mixture of ceramic particles and metal powder. The supply pipe (51) and the cooling water pipe (52) for cooling the torch (5) are connected.

Then, the molten metal which is the centrifugal casting material is poured from the ladle (6) into the pouring gutter (4). At the same time, the second intake (42)
From the above, a high temperature of the plasma arc generated in the torch forms a droplet in which ceramic particles and metal particles are mixed with each other, and the droplet is mixed with the molten metal at a constant ratio.

From the pouring trough (4), the molten metal is poured into the rotating mold (1) at a constant speed.

As the metal to be poured from the first intake port (41), high-grade cast iron, ductile cast iron, alloy cast iron, iron-based metals such as cast steel or non-ferrous metals such as Al and Cu and alloys thereof are appropriately selected depending on the application.

Examples of the ceramic particles include SiO ₂ , Al ₂ O ₃ and ZrO.
₂ , oxides such as BeO, carbides such as TiC and SiC, and TiN and Si ₃
Particles of 50 μm to 1 mm of nitride such as N ₄ are used.

In addition, the metals that melt together with the ceramics are iron-based alloys,
A cobalt-based alloy or the like can be selected.

As usual, the mold rotation speed is 40 to 200 in GNo. Low rotation is suitable for non-ferrous metals.

An outer layer of the product is formed by the above-mentioned process, and an inner layer is formed by superposing the molten metal of the components according to the use and economy of the product in a mold and stacking it on the first layer by centrifugal casting.

INDUSTRIAL APPLICABILITY As described above, the present invention can efficiently produce a ceramic-metal composite by a highly productive centrifugal casting method, and particularly in the production of large-diameter and long products, wear resistance by the conventional plasma overlay method. The manufacturing efficiency is significantly improved as compared with the case of forming a layer.

Since ceramics have virtually no melting point and have a low specific gravity, it is difficult to melt only ceramics by a plasma arc and inject them into the molten metal, and the ceramics are not sufficiently dispersed in the molten metal.

However, as in the present invention, by spraying droplets in which ceramics and metal are mixed together into a molten metal that is a centrifugal casting material, the ceramics are well mixed in the molten metal.

Further, by casting under a centrifugal force, the ceramic solidifies in a uniform distribution state in the axial direction and the circumferential direction of the roll, so that the outer circumference of the roll can have a uniform quality.

Since it is cast molding, distortion is less likely to occur as compared with the conventional case where a solid base material is coated with hot metal.

Next, a specific example of manufacturing the first layer (hereinafter referred to as a cylinder) of the outer shell cylindrical material for the transport roll will be described.

Shape of cylindrical object Outer diameter 100 mm, length 260 mm, wall thickness 20 mm Ratio of ceramics occupying in the cylinder 5% Metal component that melts together with ceramics by plasma arc SCH22 Mixing ratio of the above metals to ceramics 20% Melt temperature 1700 ℃ The mold is heated to 150 ℃ and the mold speed is set to 600 rpm.

As a result, a wear-resistant cylinder having ceramics uniformly dispersed in the axial direction and the circumferential direction was obtained.

The present invention is not limited to the configuration of the above embodiment,
Various modifications are possible within the scope described in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view showing the outline of a centrifugal casting apparatus used in the present invention. (1) …… Centrifugal casting mold, (4) …… Injection gutter (5) …… Plasma torch

Claims (1)

[Claims] 1. A ceramic-metal composite obtained by melting ceramics and metal by high heat of a plasma arc, mixing the droplets with a metal melt which is a centrifugal casting material, and solidifying the mixed melt under centrifugation. Production method.