JPS58130202A - Production of sintered body - Google Patents

Abstract

PURPOSE:To prevent failue of powder moldings during handling in the stage of producing sintered bodies of long-sized green compacts of W and Mo by pressurizing and extrusion molding powders of W and Mo to a continuous powder molding with a throat, and conducting electricity thereto with two pieces of electrodes thereby sintering the molding. CONSTITUTION:In the stage of producing long-sized sintered bodies of high m.p. metallic powders of W, Mo, etc., the above-mentioned metallic powders are supplied through a supply port 2 into a throat 1. The screw 4 in the throat 1 is rotated to compress the metallic powder which is then removed as a long-sized molding continuously through a delivery port 3. The preceding end part of the throat 1 is enclosed with a chamber 6, and the inside thereof is put in a reducing atmosphere of gaseous hydrogen or the like. Eelectricity is conducted to the molding with two pieces of electrodes 5, 5 disposed in the preceding end part of the throat whereby the molding is sintered and the powder sintered body 8 of W and Mo is produced in a long size state. Since there are no stages for handling the molding prior to the sintering by manual labor, the long-sized sintered body free from fracture during handling is produced easily.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a sintered body using an electric current sintering method.

[Technical background of the invention]

Tungsten hoods, commonly used for filaments, etc.
In order to produce a sintered body made of a high melting point metal such as molybdenum (Mo), gold ki4! The IJ powder is pressurized with a press to form a rod-shaped powder compact, and electrodes are connected to both ends of the powder compact and the compact is sintered by applying electricity.One method is the current sintering method. rows are displayed.

[Problems with background technology]

However, this manufacturing method has the following problems. From the point of view of production efficiency, it is preferable for the powder compact to be as long as possible, but in reality, there is a limit to the length of the powder compact to be compacted due to the production steering force of the press equipment and the scale of the equipment. It is difficult to mold long objects. if,
Pressure molding of a long powder compact requires a press apparatus of a very large scale, which is practically impossible in terms of the scale of the equipment and economic efficiency.

Similarly, when carrying out electrical sintering, there is a limit to the length of the powder compact to be sintered due to the size of the sintering apparatus, and it is impossible to conduct electrical sintering of a long powder compact.

In addition, unlike sintered bodies, powder compacts have low mechanical strength, but if they are rod-shaped, they are more likely to break due to their shape, resulting in a risk of yield loss. It takes a lot of effort to handle the compost, such as transporting it to the equipment. % high single-point metal powder compacts are hard and brittle, so they are easily damaged.

[Purpose of the invention]

The present invention provides a method for manufacturing a sintered body that is capable of producing a long powder compact and solves the difficulty of handling the powder compact.

[Disclaimer of invention]

The method for producing a sintered body of the present invention involves pressurizing the powder supplied to the throat and continuously extruding it from the throat to form a long powder compact. By sintering the powder compact by passing it through the electrodes while extruding it, the handling of the powder compact is made difficult.

[Embodiments of the invention]

The drawings show an embodiment of the manufacturing method of the present invention.

In the manufacturing method of the present invention, an apparatus shown in the drawings as an example is prepared. In the figure, 1 is a throat, at one end of which a tungsten or molybdenum powder supply port 2 is formed, and at the other end;
A powder compact delivery port 3 is provided in the form of a rectangular (or round, depending on the momme) cylindrical shape. Inside the throat 1 is an electric th! The screw 4, which is driven 10 rotations as /c, is rotated along the axial direction.

A pair of electrodes 5.5 connected to a power source (not shown) are arranged on both sides of the front end of the outlet 3 in the throat 1, and the inner surfaces of the 11 electrodes 5, 5 are tapered to match the sintering shrinkage of the powder. is doing. The outlet port 3 of the throat 1 and the electrode 5.
A chamber 6 is provided surrounding the chamber 5, and the inside S of the chamber 6 is made into a reducing atmosphere by hydrogen gas or the like.

This is to prevent oxidation, as tungsten and molybdenum, among metals, are subject to high oxidation consumption at high temperatures.

A case will be described in which the manufacturing method of the fourth brother is implemented. The gold powder 7 is supplied into the throat 1 from the supply port 2. By rotating the screw 4 with an electric motor, the powder 7 supplied into the throat 1 is moved forward toward the delivery port 2.

The powder 7 is pressurized by the screw 4 during this process. The powder 7 pressurized and sent to the delivery port 3 by the screw 4 passes through the tapered delivery port 3 and is sequentially released outward as a pressurized rod-shaped powder compact from the opening at one end of the delivery port 3. It is continuously extruded towards. Screw 4 like this
The powder 7 is pressurized by the rotation of and continuously extruded as a rod-shaped powder compact. That is, a long powder compact is pressure-molded.

Next, the powder compact extruded from the outlet 3 of the throat 1 successively passes between electrodes 5, 5 provided in front of the outlet 3.

*The power supply circuit connecting the electrodes 5 and 5 is closed, and the power flows between the d1 electrode 5 and the electrode 50 through the powder compact passing between these electrodes 5 and 5. For this reason, the powder compact is sintered by being energized when passing between the electrodes 5.5, and becomes a sintered compact 8 after passing between the electrodes 5.5. Note that this process is carried out in a reducing atmosphere in the internal VC of chamber 6 in order to prevent oxidative consumption during sintering. Immediately after being extruded, the material passes through electrodes s, si&ll sequentially and is sintered with electricity, and then a sintered body 8 is continuously formed and sent from the chamber 6. Therefore, since the powder compact can be subjected to energization sintering directly after being press-molded, the process in which workers handle the powder compact, which is easily damaged, is completely sluggish. Furthermore, since the powder compact is transferred and passed between the first poles 5, 5, a long powder compact can be electrically sintered.

The speed of extrusion of the powder compact from the throat 1, the pressure conditions for the powder 1, and the conditions for electrically sintering the powder compact 80 are determined.

The density of the sintered body 8 can be determined by the magnitude of the current flowing through the electrodes 5, 5. For example, at a current of about 420% of the melting current, the density of the sintered body is 50 to 55% of the theoretical density. Therefore, with a current of 30% density, the density is about 60. Specifically, when a current of IOV and 60 A is passed through a powder molded body made of molybdenum in the shape of a rectangular rod, a sintered density of approximately 6.597 cm'' is obtained.

The means for pressurizing and extruding the powder inside the throat 1 is not limited to the screw, and other methods such as using a press punch can be used.

〔Effect of the invention〕

The uninvented method for producing a sintered body pressurizes the powder in the throat and continuously extrudes it from the throat, making it possible to form a long powder compact and allowing it to be used from the IHL throat. Since the powder compact is continuously passed between the electrodes and sintered by energization, there is no need for workers to handle fragile powder compacts, which prevents breakage of the compact. Sintering is possible.

[Brief explanation of the drawing]

The drawing is a diagram showing an embodiment of the manufacturing method of the present invention.

Claims (3)

[Claims] (1) Supply metal powder into the throat, pressurize the metal powder, continuously extrude it through the outlet of the throat, and sinter the extruded powder compact by passing it between electrodes while applying electricity. A method for producing a sintered body, characterized by: (2) The method for producing a sintered body according to claim 1, wherein the sintering is performed in a reducing atmosphere. (3) The method for producing a sintered body according to claim 2, wherein the metal powder is tungsten or molybdenum.