KR20080099526A - The manufacturing method of a tungsten heavy alloy - Google Patents

Abstract

A manufacturing method of a tungsten heavy alloy tube is provided to apply even in case the tungsten content is low, no loss of material and organization and density are uniform. A manufacturing method of a tungsten heavy alloy tube including the step following: a step for mixing the powder selected between the iron(Fe), the nickel(Ni), and the copper(Cu) powder in the tungsten powder more than the first class; a step for molding powder molded body of the tube-like having the same inside diameter as the product inside diameter which is finally accomplished by using the pulverulent compound mixed in the process; a step inserting the core having the same diameter as the inside diameter of the powder molded body into the powder molded body; a step for in the sintering furnace which maintaining, the powder molded body in which core is inserted is made with liquid sintering method the temperature condition more than the eutectic point of mixture; and a step for removing core from the tungsten heavy alloy sintered on liquid phase.

Description

The manufacturing method of a Tungsten Heavy Alloy}

1 to 3 is a schematic view showing a variety of manufacturing process of the conventional tungsten alloy gold tube.

Figure 4 is a block diagram schematically showing a series of manufacturing process as a manufacturing process chart of a tungsten polymer alloy tube according to the present invention.

Figure 5 is a schematic diagram showing a manufacturing process of the work force as a manufacturing process chart of the tungsten polymer alloy tube according to the present invention.

Figure 6 is a photograph of the powder compact for the production of tungsten polymer gold tube according to the present invention.

7 is a photograph of a tungsten polymer gold tube prepared according to an embodiment of the present invention.

8 is a photograph showing a comparative example with respect to FIG.

The present invention relates to a method for producing tungsten polymerized gold, and more particularly, to a method for producing a tungsten polymerized gold tube having a uniform structure and density without loss of material using cores.

In general, tungsten polymerized gold is a kind of composite material containing tungsten (W) as a main raw material and containing nickel (Ni) and iron (Fe) or nickel and copper (Cu). Tungsten polymerized gold has high density and excellent tensile strength, and thus is widely used as a radiation shielding material, a cell penetrator, and a penetrator material for kinetic energy bombs for armored vehicles.

Tungsten polymerized gold is mainly produced through liquid phase sintering. This is usually produced by mixing a tungsten, nickel and iron powder as a powder in a predetermined ratio to produce a powder molded body and then sintering at a high temperature through a sintering furnace to maintain the temperature conditions above the process point of nickel and iron, which is included in the powder molded body Nickel and iron form a liquid phase during the sintering process to form a tungsten polymer alloy material in which two different phases, tungsten and liquid phase, are formed.

Therefore, the amount of liquid is changed according to the amount of nickel and iron contained in the tungsten polymerized gold, and when such a liquid phase is generated, the strength of the powder compact is weakened, causing a severe deflection phenomenon under the influence of gravity during sintering. In particular, when the content of tungsten in the tungsten polymer alloy is low or the size of the product is large, such a sagging phenomenon is aggravated.

In the case of tungsten polymerized gold, the content of tungsten is usually 90 to 98% by weight. In this case, the liquid phase inside the powder compact during sintering is less than 20% of the total volume by volume, so that the above-mentioned sagging phenomenon is not large during sintering. However, in the case of tungsten polymerized gold having a content of tungsten of 80 wt% or less, the liquid phase inside the powder compact during sintering is about 40% of the total volume on the basis of the volume, and very severe deflection occurs during sintering.

This problem will be described in connection with a method of manufacturing a tube using a conventional tungsten polymer alloy.

1 to 3 are schematic views illustrating various processes of manufacturing a tube using a conventional tungsten polymer alloy. In manufacturing a tube using a conventional tungsten polymer alloy, three methods shown in the drawing are used. Looking at it by the manufacturing method as follows.

Manufacturing Method 1

Method 1 shown in Figure 1, by mixing the tungsten, nickel and iron powder to form a powder compact in a cylindrical shape, and then sintering the powder compact through a sintering furnace maintained at a high temperature temperature, and the sintered product It is a method to finish the product in the desired tube shape through machining.

However, in the case of Method 1 as described above, the larger the product and the larger the amount of liquid, the greater the deflection during liquid phase sintering, and the corresponding material is lost during the inner diameter of the tube, so the loss of the material is very large, the machining time is long, and the tool consumption is increased. .

In addition, when the size of the molded body is large, the liquid phase is generated from the surface of the molded body due to the temperature difference between the inside and the outside of the molded body during sintering, so that the tungsten particles are driven to the outside close to the surface and sink down under the influence of gravity, resulting in uneven structure and density. there is a problem.

Manufacturing Method 2

Method 2 shown in Figure 2, by mixing the tungsten, nickel and iron powder to form a molded body in a cylindrical shape, and then liquid phase sintering the powder compact through a sintering furnace maintained at a high temperature temperature, the tube shape by hot forging After machining, the desired tube shape is machined.

According to this method, since the size of the initial molded product is smaller than the production method 1, the input weight of the initial material is small, but the loss of the material is generated similarly to the production method 1 described above, and the production cost due to the addition of the hot forging process There is a disadvantage that increases.

In addition, there is a difference in degree because the size of the initial molded body is smaller than that of the manufacturing method 1, but this method also has a large surface of the tungsten particles because the liquid phase is generated from the surface of the molded body due to the temperature difference between the inside and the outside of the molded body during sintering. There is a problem of unevenness of tissue and density due to the influence of gravity sinks down toward the outside.

Manufacturing Method 3

Method 3 shown in Figure 3, using a powder mixture of tungsten, nickel and iron powder to form a powder compact in the form of a tube from the beginning, and then the powder compact through a sintering furnace to maintain high temperature conditions Sintering, and finally machining to form the desired shape.

In the case of this method, since the amount of processing is smaller than the above-described methods 1 and 2, the loss and cost of the material is low, and the thickness of the initial molded body is thinner than the manufacturing methods 1 and 2, so that the temperature difference between the inside and the outside of the molded body during sintering is relatively As it occurs less, it has the advantage of uniform density and density during sintering. However, when the sintering is worse than the manufacturing method 1 or 2, the deflection phenomenon is severe, so it is difficult to apply when the tungsten content in the tungsten alloy gold is low.

The present invention is to provide a method for producing a tungsten polymer alloy tube that can be applied even when there is no loss of material, uniform structure and density, and low tungsten content in order to solve the above conventional problems.

In order to achieve the above object, the present invention is a tube-like powder having the same inner diameter as the product inner diameter to be finished by mixing at least one powder selected from iron (Fe), nickel (Ni), copper (Cu) powder with tungsten powder After molding the molded body, the powder compact with the core inserted therein is liquid-sintered in a sintering furnace in which a core having the same diameter as the inner diameter of the powder compact is inserted into the powder compact and maintaining a temperature condition above the process point of the mixture. Provided is a method for producing a tungsten polymer gold tube in which a core is removed from a liquid-sintered tungsten polymer gold to produce a tube-shaped tungsten polymer gold.

Here, the powder compact may be a mixture of at least one powder selected from iron (Fe), nickel (Ni) and copper (Cu) powder in 70 to 98% by weight of tungsten powder, the remaining weight percent of The core is preferably made of a ceramic material.

Hereinafter, a series of manufacturing methods for producing a tungsten polymer gold tube according to the present invention will be described in detail.

The core of manufacturing the tungsten polymer alloy tube applied to the present invention is to produce a tungsten polymer alloy tube by liquid-sintering a powder compact including tungsten powder, and to prevent sagging of tungsten particles during the sintering process. The point is to sinter by inserting a core into the core.

As such, when the core is inserted in the sintering process, a compressive force for compressing the core is generated in the process of shrinking the powder compact during liquid phase sintering, and thus the core and the powder when the molded body is sagging due to the formation of a liquid phase in the powder compact. Due to the friction force generated between the molded bodies, sagging as in the prior art does not occur.

With reference to the accompanying drawings will be described in detail a manufacturing method according to the present invention.

4 to 5 shows a manufacturing process diagram of the tungsten polymer alloy tube according to the present invention, Figure 4 is a block diagram according to the manufacturing process, Figure 5 is a schematic schematic diagram of the manufacturing process.

Referring to the drawings, tungsten powder is used as a main component, and at least one powder selected from iron (Fe), nickel (Ni), and copper (Cu) powder is mixed. Preferably, 2 to 30% of the at least one powder selected from iron (Fe), nickel (Ni), and copper (Cu) powder is mixed with 70 to 98% by weight of the tungsten powder based on 100% by weight.

Next, the powder compact is molded using the mixed mixture, and the powder compact is molded into a hollow tube shape having the same inner diameter as the inner diameter of the finished product. Powder compacts may be molded through ordinary cold isostatic pressing (CIP).

Subsequently, a core having the same diameter as the inner diameter of the powder compact is inserted into the powder compact and then liquid phase sintered in a sintering furnace maintaining a temperature condition of a predetermined temperature or more. The core is a core made of ceramic having excellent heat resistance, and in the sintering furnace, the temperature at which each component of the eutectic mixture precipitates as a crystal when considering the melting point of the mixture (Fe, Ni, Cu) mixed as a sintering material The phosphorus process point is maintained at a temperature above (1300 ° C. to 1550 ° C.) and in a reducing atmosphere. In some cases, a core made of a material selected from graphite, tungsten, and molybdenum may be used, and solid state sintering may be preceded to achieve a density of approximately 95% of the powder compact before liquid phase sintering.

According to a series of manufacturing procedures for the production of tungsten polymer alloy tube as described above, before sintering the powder compact, liquid sintering is carried out with a core having the same diameter as the inner diameter of the powder compact inserted into the powder compact. .

When the core is inserted before sintering, a compressive force for compressing the core is generated in the process of shrinking the powder compact during liquid phase sintering. Accordingly, when the molded body is to be sag due to the formation of a liquid phase inside the powdered body, the sag is not caused by the friction force generated between the core and the powdered body.

Hereinafter, the present invention will be described in more detail with reference to preferred embodiments.

(Example)

The weight ratio of nickel (Ni) and iron (Fe) to 82% by weight of the tungsten powder was mixed with 13% by weight and 5% by weight, respectively, to form a tube-shaped powder molded article having an inner diameter equal to the inner diameter of the finished product (see FIG. 6). ).

A ceramic core having the same diameter as the inner diameter of the molded powder compact was inserted in the center of the powder compact, and then liquid-phase sintered in a sintering furnace maintained at a temperature above the process point of nickel and iron (approximately 1460 ° C).

The final tungsten polymer alloy tube is shown in Figure 7 through this embodiment.

(Comparative Example)

The weight ratio of nickel (Ni) and iron (Fe) to 82% by weight of the tungsten powder was mixed with 13% by weight and 5% by weight, respectively, to form a tube-shaped powder molded article having an inner diameter equal to the inner diameter of the finished product (see FIG. 6). ).

The molded powder compacts were liquid-phase sintered in a sintering furnace maintained at a temperature above the process point of nickel and iron (approximately 1400 ° C.).

The final tungsten polymer alloy tube is shown in FIG. 8 through the comparative example.

When comparing the final molded product picture with reference to Figure 7 to 8 attached, in the case of the tungsten polymer alloy tube according to the embodiment as shown in Figure 7 in addition to the original powder compact shape as shown in Figure 7 It can be seen that there is no change in shape or sag on either side. This results in a compressive force compressing the core in the process of shrinking the powder compact during sintering, and thus a frictional force against deflection between the core and the powder compact by the compressive force when the compact is about to sag due to the formation of a liquid phase in the powder compact. This is because it occurred.

On the other hand, in the case of the comparative example without using the core it can be seen that the final molded product shape is severely distorted as shown in FIG. This is because, due to the temperature difference between the inside and the outside of the molded body during sintering, since the liquid phase is generated from the molded body surface, the tungsten particles are driven to the outside close to the surface, and the structure and the density become uneven while sinking downward under the influence of gravity.

As such, when the tungsten polymer alloy tube is manufactured through the manufacturing method according to the embodiment of the present invention, no tangle of tungsten particles due to gravity is generated during the sintering process, thereby making it possible to manufacture high quality tungsten polymer tube with high reliability.

The present invention has been shown and described with reference to certain preferred embodiments, but the present invention is not limited to the above-described embodiments and has ordinary skill in the art to which the present invention pertains without departing from the concept of the present invention. Various changes and modifications are possible by the user.

According to the present invention as described above, the pulling of the tungsten particles by gravity does not occur at all during the sintering process. Therefore, a separate machining is not required for forming a left product as in the prior art, and thus machining can be omitted, thereby minimizing material loss.

In addition, since the tungsten particles do not occur, the structure and density of the final product is very uniform, so that the reliability of the product can be further improved, and even when the tungsten content is low, there is a general advantage.

Claims (3)

Mixing at least one powder selected from iron (Fe), nickel (Ni), and copper (Cu) powder with tungsten powder; Molding a tube-shaped powder compact having an inner diameter equal to that of the final finished product using the powder mixture mixed in the process; Inserting a core having the same diameter as the inner diameter of the powder compact into the powder compact; Liquid-phase sintering of powder-inserted bodies into which cores are inserted in a sintering furnace to maintain a temperature above a process point of the mixture; And Removing core from the liquid sintered tungsten polymer gold; Method of manufacturing a tungsten polymer gold tube comprising a. The method of claim 1, Powder moldings, Method for producing a tungsten polymer alloy tube, characterized in that at least one powder selected from iron (Fe), nickel (Ni), copper (Cu) powder is mixed within 70% to 98% by weight of tungsten powder . The method of claim 1, A core is a method for producing a tungsten polymer alloy tube, characterized in that the ceramic material.

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