JPS6092461A - Power metallurgical method of metallic compound - Google Patents

Abstract

PURPOSE:To form a metallic compd. material which is densely and finely crystallized by converting metallic powder together with a reactive gas to plasma by plasma spraying method and spraying thermally and depositing the metallic powder on a substrate then heating the substrate to melt and metallic powder by laser light and cooling quickly the molten powder. CONSTITUTION:Metallic powder (for example, titanium) is supplied through a powder supply port 2 and a reactive gas (for example, gaseous nitrogen) which combines with a metal is supplied through a carrier gas feed path 3 then a high voltage is impressed between a cathode 4a and an anode 4b to convert the carrier gas to plasma by arc discharge with a plasma spraying device 1. The metallic powder is then heated to melt and is sprayed and deposited on a substrate 5. High-output laser light 8 is focused by a lens 9 and is irradiated to the deposited metallic part to melt thoroughly the metallic powder by which the combination with the reactive gas is accelerated. The thermally sprayed part of the substrate 5 is cooled from the rear by the cooling water supplied to the jacket 10.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to powder metallurgy of metal compounds.

In the conventionally known plasma spraying method, metal powder is turned into plasma by arc discharge together with a carrier gas, and then sprayed and deposited on the substrate. The central part of the metal is deposited by thermal spraying while remaining unmolten, and the thermally sprayed film therefore contains metal powder with a large particle size and has many pores.

The present invention provides a powder metallurgy method in which a desired metal compound material is produced by further accelerating the melting of the metal powder by laser heating and at the same time bringing the molten metal into contact with reactive scum activated by arc discharge. This is what we are trying to provide.

In order to achieve this object, the powder metallurgy method of the present invention combines the carrier residue with the metal to be sprayed in a plasma spraying method in which metal powder is turned into plasma by arc discharge together with a carrier gas, and then sprayed and deposited on a substrate. The deposited part of the metal powder is irradiated with a high-power laser beam to rapidly heat and melt the sprayed film, and is combined with the reactive gas to form a metal compound material. The part is rapidly cooled to produce a dense, finely crystallized metal compound material.

The method of unreleased 1jl will be further explained below with reference to the drawings.

The powder metallurgy method of the present invention utilizes a conventionally known plasma spraying technique, uses a reactive gas as a carrier gas, and irradiates the deposited area of metal powder with a high-power laser beam. A known plasma spraying apparatus 1 as shown in FIG. 1 can be used as is.

The plasma spraying apparatus 1 supplies metal powder to be sprayed from a metal powder supply port 2, and also applies a high voltage between a cathode 4a and an anode 4b while supplying a reactive gas to a carrier gas supply path 3. The carrier scum is turned into plasma by arc discharge, thereby heating and melting the metal powder, which is sprayed and deposited on the substrate 5. Conventionally, in such a plasma spraying apparatus, a carrier gas that does not react with the metal powder is generally used, but in the present invention, a reactive gas that actively reacts with the metal is used as the carrier gas. Use 1 For example, when titanium is used as the metal powder.

Using nitrogen gas as a reactive gas, a sprayed titanium nitride lI8 is generated on the substrate 5.

Note that it is necessary to place the metal powder in a molten state in the above-mentioned reactive gas atmosphere. For this reason, it is desirable to place the entire apparatus in a pressure-adjustable container 11 so that the pressure of one reaction gas can be adjusted.

In the case of thermal spraying using the above-mentioned thermal spray film @l, the central part of the metal powder is deposited by thermal spraying while remaining unmelted. Therefore,
A high-power laser beam 8 from a laser light source (not shown) is focused and irradiated with a lens 8 onto the portion where the metal powder is deposited, thereby completely melting the metal powder.

When the metal powder is completely melted in this manner, its combination with the reactive gas is promoted, and a sprayed film 6 of the metal compound material is formed on the substrate 5.

If the thermal sprayed coating 8 of the metal compound material is allowed to cool as it is, crystals will grow, but by rapidly cooling it, the amorphous or crystal grains will condense in a fine state. A film is produced. Therefore, the thermal sprayed film 8 is immediately cooled, and the first stage of cooling may include cooling the thermally sprayed portion of the substrate 5 with cooling water supplied from behind to the water cooling jacket 1O, as shown in the figure, or blowing cold air. The following method can be used.

Further, as shown in Fig. wS2, when a sprayed film is to be formed on a tubular substrate 15, cooling water can also be made to flow within the tubular substrate 15.

According to the method of the present invention, the metal powder sprayed by the plasma spraying method is irradiated with a high-power laser beam to completely melt the metal powder to the center, which is different from the conventional plasma spraying method. It does not contain many pores like sprayed coatings do, and the powder metal melts sufficiently to easily react with reactive gases.
Both reactions are sufficiently promoted. Furthermore, by rapidly cooling the deposited sprayed film of the metal compound material, the crystals of the metal compound are made fine or amorphous, and a sprayed film of the metal compound material with excellent mechanical properties can be obtained.

Furthermore, since the powder metal has already been melted to some extent by arc discharge, there is no need to make the laser beam's powder density particularly high (I/%).

According to the method of the present invention, materials such as titanium nitride, which conventionally could only be formed as a very thin film by vapor deposition, can be obtained as a relatively thick thermal sprayed film.

[Brief explanation of the drawing]

FIGS. 1 and 2 are explanatory diagrams showing different implementation states of the present invention. 5. Substrate, 6. Sprayed film, 8. High output laser beam.

Claims (1)

[Claims] 1. In a plasma melting method in which metal powder is turned into plasma by arc discharge together with a carrier gas, and sprayed and deposited on a substrate, the carrier gas is used as a reactive gas that combines with the metal to be sprayed to produce a metal compound material, 2. High-power laser light is irradiated onto the deposited area of the metal powder to rapidly heat and melt the sprayed film, which is then combined with the above-mentioned reactive gas, and then the area is rapidly cooled to form a dense, finely crystallized metal. A powder metallurgy method for metal compounds characterized by producing a compound material.