JPS60138029A - Production of metallic powder molding - Google Patents

Abstract

PURPOSE:To enable production of a powder molding consisting of an Ni-Ti alloy having high precision in an assembly grade by adding powder of Ni or Ti at a specific value or below according to the compsn. of the Ni-Ti alloy to the powder of said alloy and molding the mixture under pressure. CONSTITUTION:Ni pellets and sponge Ti are mixed and the mixture is melted in a gaseous Ar atmosphere in a plasma melting furnace in the stage of producing an Ni-Ti shape memory alloy contg. 56% Ni and 44% Ti. The molten metal is dropped onto a disc under high-speed rotation and is thus scattered, by which the powder of the Ni-Ti alloy is produced. The compsn. of the powder alloy is analyzed and the insufficient component in the compsn. deviated from the above- mentioned compsn. is added in the form of hydride to the alloy in a <=10% range to adjust the components. The alloy is directly rolled with rolling rolls, by which the plate-shaped molding of the Ni-Ti alloy having high precision with respect to the target compsn. and having an excellent shape memory characteristic is produced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a metal powder compact with improved precision of metal composition.

For example, in shape memory alloys, the transformation temperature changes greatly depending on slight differences in the composition of the metal components constituting the alloy. In such a case, it is needless to say that it is necessary to improve the precision of the metal composition constituting the alloy. For example, many shape memory alloys have high hardness and poor cold workability and mechanical workability. The powder metallurgy method to obtain the desired shape was awarded.

Conventionally, in the powder metallurgy method, in order to obtain a molded body with a predetermined metal composition, a method is used in which a mixture of powders of individual metal components constituting the molded body in a predetermined ratio is used as a molding material, and a method is used to form the molded body. A method has been proposed in which a molding material is prepared by mixing two or more kinds of alloy powders of two or more kinds of metal components in a predetermined ratio.

However, with the former, it is difficult to obtain a product with a uniform composition because the metal powders are difficult to penetrate and diffuse into each other during sintering after forming.
Also, highly active metals such as titanium have disadvantages such as the need to sinter in an inert atmosphere, and the latter requires the creation of alloys of various compositions in order to obtain compacts of arbitrary compositions. There is a problem that requires you to do this. Furthermore, it is possible to create an alloy with a predetermined composition and powder it to use as a molding material, but when creating an alloy by the melting method, it is inevitable that there will be a minimum error of 0.1% in the composition. However, in the case of a titanium-nickel alloy, the above-mentioned error of 0.1% actually results in an error of 15° C. in the transformation temperature.

The present invention aims to improve the above-mentioned conventional drawbacks and obtain a uniform metal powder molded body with high precision of metal composition. The gist is to apply pressure to a mixture to which one or more raw materials providing the metal components constituting the one or more alloy powders are subjected to molding.

The invention will be explained in detail below.

An alloy containing one or more third components such as zirconium, cobalt, chromium, tantalum, vanadium, molybdenum, niobium, palladium, platinum, manganese, iron, etc., and a gold-cadmium alloy.

Silver-Cadmium Alloy 9-Silver-Cadmium Alloy.

It includes all types of alloys such as copper-aluminum-nickel alloy and copper-zinc alloy. The above examples are not intended to limit the invention. The alloy is used either as a single type or as a mixture of two or more types in a predetermined ratio, and is mixed so that the metal composition is as close as possible to the predetermined composition of the molded product.For example, in the case of a titanium-nickel alloy, further addition In order to obtain a product with a uniform composition, it is desirable that the amount of nickel and/or titanium raw materials added does not exceed 10% by weight as nickel μ and/or titanium.

The raw materials added to the above alloy or alloy mixture include a single metal component constituting the alloy or alloy mixture, or a compound that provides the metal component by sintering.

Such compounds include oxides, chlorides, mineral acid salts, etc. of certain metals. These compounds are reduced to their respective metals by sintering in a reducing atmosphere. More desirable compounds include metal hydrides. The metal hydride generates hydrogen during sintering, forms a reducing atmosphere, prevents undesirable metal oxidation, and participates in the reduction of the compounds mentioned above. Examples of the metal hydride include palladium hydride and titanium hydride. The above examples are not intended to limit the invention.

The molding material made of the above-mentioned alloy or alloy mixture further mixed with the above-mentioned raw materials may further contain polyvinyl alcohol μ and sodium alginate, if desired.

Poxymethylcellose, methylcellulose, ethylcellulose, methoxycellulose, ethoxycellulose, casein, gluten, gum arabic.

Starch, modified starch, acrylic μ resin, 7-tyrene resin.

Vinyl acetate resin, styrene-butadiene copolymer.

A third component such as one or more binders such as phenol resin, urea resin, melamine resin, and urethane resin, a lubricating agent such as fatty acid salt, silicone oil, and glycerin may be added. The above examples are not intended to limit the invention.

The above-mentioned molding material thus prepared is pressed into a predetermined shape by, for example, being filled into a mold and press-molded or rolled with a rolling mill μ, and if desired, subjected to grinding, etc. After undergoing post-processing, it is sintered, and then, if desired, further post-processing such as grinding is performed to produce a product.

Since the present invention has the above configuration, there is no need to create alloys with various compositions in order to obtain a molded product with a predetermined composition.
Most simply, it is possible to finely adjust the composition to a desired composition by adding the above raw materials to just one type of alloy, and in the case of titanium-nickel alloys, the powder has a nearly spherical shape. Since mutual entanglement is difficult to occur and therefore formability is low, hot pressing has been used as a forming method, but according to the present invention, a raw material that provides titanium and/or nickel is further added to the titanium-nickel alloy. As a result, in addition to fine-tuning the composition, the unexpected effect of improving moldability was obtained.

Examples for explaining the present invention in more detail will be described below.

Example 1 Weighed 11.2 kq and 8.8 kg of pellet-like nickel and sponge-like titanium, respectively, so that the nickel content was 56% by weight and the titanium content was 44% by weight, and these were put into a plasma melting furnace with a power output of 220kw/. The ingots were melted in an ATM argon gas atmosphere to obtain ingots with a diameter of 110 ar, a height of 300 ar, and a weight of 20 #. Approximately 5 kq of material was obtained by cutting the ingot, which was placed in a high-frequency induction furnace and melted in an argon gas atmosphere, and poured onto a disk rotating at high speed.
It was dispersed by centrifugal force to obtain titanium-niraglu alloy powder. As a result of analyzing the alloy powder, nickel/l156.2
It was 96.

Using this titanium-nickel alloy powder, the transformation temperature (A
f) Add and mix 1% titanium powder to make a thin plate at 50°C, →su←−=The mixture is directly charged into a rolling roll and continuously rolled to make a 0.5t x 60w plate-shaped compact. I got it. The molded product had high mechanical strength and could be held in the hand as it was, and could also be wound into a coil.

This coil was placed in a vacuum furnace and sintered at 1050°C for 4 hours, followed by cold rolling to obtain a thin plate of 90.2t x 60w.

When the transformation temperature of this thin plate was measured, Af=52° C., which was extremely close to the target value.

Patent applicant: Daido Steel Co., Ltd.

Claims (5)

[Claims] (1) A mixture in which one or two or more types of alloy powder consisting of two or more metals is further added with one or more types of raw materials that provide the metal components constituting the one or more types of alloy powder. A method for producing a metal powder compact, characterized by forming by applying pressure. (2) The method for producing a metal powder compact according to claim (J), wherein the shaping is performed by directly rolling the mixture. (3) The method for producing a metal powder compact according to claims (1) and (2), wherein the alloy is characterized by nickel and titanium. (4) The raw material provides nickel and/or titanium components, and the added amount of nickel and/or titanium does not exceed 10% by weight of the mixture as described in 1-Claim (3). Method for manufacturing a metal powder compact (5) A method for producing a metal powder compact according to claim (1), wherein part or all of the raw material is a metal hydride.