JPH0421769A - Sublimable metallic material for vapor deposition - Google Patents

Abstract

PURPOSE:To stabilize the vaporization rate and to carry out stable vapor deposition by using the powdery or lumpy material having a specified grain diameter to be heated by an electron beam. CONSTITUTION:Cr as the sublimable metallic material 8 is placed in a raw material vessel 7 of a vapor-deposition chamber 1, heated by an electron beam 5 from an electron gun 4 and vaporized, and Cr vapor is continuously deposited on a continuous steel strip 2 traveling continuously above the vessel. The vaporization behavior is changed by the size of the material 8, and the vaporization amt. is not stabilized when the relatively large material 8 is used. Accordingly, the granular or lumpy material 8 having 3-50mm average grain diameter is used. Consequently, the effective electron beam energy irradiating the surface of the material 8 is determined, and the vaporization amt. is stabilized. The material is blown up at <3mm average grain diameter, and the vaporization amt. is not stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to sublimable metal materials such as Cr, Mn, Co, and Mg. The present invention relates to a sublimable metal material that can be used in vapor deposition plating and allows for stable operation.

[Prior Art] When performing vacuum evaporation plating, the metal material to be evaporated is heated and evaporated using an appropriate heating means, and the generated metal vapor is deposited on the substrate to form a evaporation film. are doing. Various heating methods are used as the heating means, such as electron beam heating, laser beam heating, resistance heating, and high-frequency induction heating. Heating by an electron beam with high power and high energy density is often used because it has certain advantages.

By the way, when a metal material is heated and evaporated by the above-mentioned heating means in a vacuum, the melting point of a normal metal material is considerably lower than the temperature at which the vapor pressure is sufficiently increased, so the usual procedure is to use a crucible, etc. The metal material is first melted in the raw material bath, and the temperature is further increased to evaporate metal atoms from the surface of the molten metal bath. Therefore, the effective area for evaporation is determined by the surface area of the molten metal bath, and the amount of evaporation under high vacuum can be controlled primarily by thermal energy.

However, sublimable metals such as Cr and Mg exhibit high vapor pressure under high vacuum conditions even at temperatures below the metal's melting point. Evaporation from the At this time, the entire surface of the metal material becomes the effective area for evaporation, and not only does the effective area for evaporation vary significantly depending on the specific surface area of the metal material, but as the metal material becomes smaller as evaporation progresses, the effective area for evaporation decreases. Change over time. Therefore, even if the applied thermal energy is kept constant, the amount of input energy per unit area, that is, the power density changes, so it is difficult to maintain the total amount of evaporation from the total surface area of the metal material constant.

On the other hand, considering the continuous supply of raw metal materials,
Ideally, the shape of the raw material is wire or sheet, but sublimable metals such as Cr and Mg are suitable for Fe, AI, Zr,
Unlike Cu, Ti, etc., it cannot be plastically worked, and is inevitably limited to shapes such as blocks, briquettes, flakes, powders, and ingots.

[Problem to be solved by the invention] For these reasons, when using a sublimable metal material, the sublimable metal material is powdered and filled into a raw material tank, with special consideration given to the stability of evaporation. The most ideal method was to heat and evaporate it. However, such means have the following major problems. In other words, when the surface of a sublimable metal powder is irradiated with an electron beam, the powder raw material is scattered, causing dust to fly inside the deposition chamber, or some of the scattered powder entering the electron gun and causing failure of the electron beam. There were problems such as the occurrence of a continuity phenomenon (arcing phenomenon), the shortening of the life of the cathode of the electron gun, and the need for maintenance to remove powder in the electron gun.

In particular, when Cr is used as a sublimable metal material, Cr
Since Cr is a magnetic material, if a large amount of Cr is scattered, the magnetic field required to introduce the electron beam into the raw material tank will be disturbed, making it difficult to control the electron beam irradiation into the raw material tank.

When these phenomena occur, the operation itself becomes unstable as a matter of course, making it impossible to stably manufacture vapor-deposited plating products, which is extremely disadvantageous for continuous industrial production.

The present invention has been made in view of the above-mentioned circumstances, and its purpose is to provide a sublimable metal material that can stabilize the evaporation rate and realize stable vapor deposition plating operations.

[Means for Solving the Problems] The present invention, which has solved the above problems, is a sublimable metal material used when carrying out vapor deposition plating using an electron beam heating method, and which has an average particle size of 3 to 50 mm. It is a sublimable metal material for vapor deposition which is in the form of particles or lumps.

[Function] Hereinafter, the function and effect of the present invention will be described in detail along the course of the experiment.

The present inventors used Cr as a representative example of a sublimable metal material, and used the vacuum evaporation plating equipment shown in FIG. 1 to particularly investigate the influence of the size of the sublimable metal material on its evaporation behavior. That is, in FIG. 1, 1 is a vapor deposition chamber, 2 is a continuous steel strip, 3 is a support roll, 4 is an electron gun for heating Cr, and 5 is an electron beam.

6 is an exhaust port, 7 is a raw material tank, 8 is a sublimable metal material (raw material)
The sublimable metal material 8 charged into the raw material tank 7 of the vapor deposition chamber 1 kept in a high vacuum is heated and evaporated by the electron beam 5, and the surface of the continuous steel strip 2 running continuously above it is heated and evaporated by the electron beam 5. Cr vapor was continuously deposited. Incidentally, this irradiation with the electron beam 5 is performed on the sublimable metal material 8 as shown in FIG.
I did this while scanning in a zigzag pattern upwards.

As a result, it was confirmed that the evaporation behavior varied significantly depending on the size of the sublimable metal material 8.

First, it has been found that when the sublimable metal material 8 is made relatively large, the stability of the amount of evaporation becomes poor. This can be considered as follows. That is, it is difficult to charge large-sized sublimable metal materials 8 into the raw material tank 7 without gaps, and gaps inevitably occur between the metal materials 8. When an electron beam is irradiated in such a state, it is not possible to irradiate only the surface of the sublimable metal material 8 on the upper layer, and the sublimable metal material 8 on the lower layer side may be irradiated by the electron beam passing through the gap between them. In some cases, the bottom surface of the raw material tank 7 is also irradiated, so that the sublimable metal material 8 that occupies the top layer
It is thought that the effective electron beam energy irradiated onto the surface of the surface becomes uncertain, and this appears as instability in the amount of evaporation. Furthermore, when the sublimable metal material 8 is large, the effective area for evaporation tends to fluctuate as described above, and this was also thought to be a reason for impairing the stability of the amount of evaporation. However, the inventors have confirmed through experiments that if the average particle size of the sublimable metal material 8 is set to 50 mm or less, the above-mentioned disadvantages can be substantially avoided and a stable amount of evaporation can be achieved. That's what I found out. The sublimable metal material 8 in the present invention is not limited to a spherical shape, but also includes a lump-like shape. Moreover, the above-mentioned average particle size means the average of the maximum particle size in the case of a lump. Further, a more preferable average particle size is 30 mm or less, and if such a sublimable metal material is used, the above-mentioned disadvantages can be avoided most effectively.

Next, the present inventors investigated the case where the sublimable metal material 8 is very small, and found that if the particle size is less than 3 mm, the scattering phenomenon of the raw material occurs and the stability of the evaporation amount is poor. Do you get it. Especially 60 mesh under (
For particles (with a particle size of 0.4 mm or less), even if the electron beam is irradiated with a small amount of power, the raw material near the surface will scatter and spill outside the raw material tank, or in some cases, a type of material may be formed above the raw material tank. This caused the inconvenience that a "sandstorm"-like phenomenon occurred, making it impossible to carry out vapor deposition plating. Furthermore, the arcing phenomenon described above becomes noticeable.

The frequency of these phenomena can definitely be reduced by increasing the particle size, but considering the stability of evaporation amount and quality stability of vapor-deposited plating products, sublimation with a particle size of less than 3 mm It has been found that metallic materials are difficult to use.

For particles with an average diameter of about 3 to 5 mm, some scattering phenomenon may occur, but this is an unavoidable phenomenon to some extent when performing vacuum plating on sublimable metal materials by electron beam heating. However, this level of scattering phenomenon does not substantially have a particularly negative effect on the stability of the evaporation amount or the distribution of the amount of coating on the surface of the applied product. From the viewpoint of avoiding the above-mentioned scattering as much as possible, the particle size of the sublimable metal material is preferably 5111 m or more.

For the above reasons, the present inventors set the average particle size of the sublimable metal material to 3 to 50 mm, preferably 5 to 3
They found that it is sufficient to set the wavelength to 0+nm, and completed the present invention.

Hereinafter, the present invention will be explained in more detail with reference to examples, but the following examples are not intended to limit the present invention.
Any design changes for the purposes described below are included within the technical scope of the present invention.

[Example] Using vacuum evaporation plating equipment having the configuration shown in FIG. 1, continuous Cr evaporation plating treatment was performed on a strip steel plate under the following conditions using Cr in various shapes as an evaporation raw material.

Raw material shape of Cr: Various sizes of Cr were used, ranging from those with an average particle diameter of less than 0.4 ma+ to those in the form of blocks with an average length of 100 mm in the longest axis direction (Cr purity, 99.4% or more).

Raw material tank: Alumina-silica crucible Steel plate to be plated: Cold-rolled steel plate (ultra-low carbon T1 quilt steel) Pretreatment of steel plate to be plated: Off-line alkaline electrolytic degreasing, preheating by electron beam irradiation in vacuum (300°C), and surface activation treatment by Ar ion bombardment Deposition chamber Vacuum degree: 8 x 10-'TorrCr heating source, electron beam heating (electron gun power density on the raw material surface: 0.1 to 1.0 W/cm2) Line speed + 20 m/min Plating deposition amount: 3 μm (mesh W4) The results are shown in Table 1.

As is clear from Table 1, if a sublimable metal material that satisfies the requirements stipulated by the present invention is used, the material will not be scattered and will be stable regardless of the power density of the electron beam irradiated onto the surface of the evaporated material. A high evaporation amount was obtained, and a vapor-deposited Cr-plated steel sheet of excellent quality was obtained.

[Effects of the Invention] The present invention is constructed as described above, and a sublimable metal material that can stabilize the evaporation rate and realize stable vapor deposition plating operations has been obtained.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram illustrating a vacuum evaporation plating method using a sublimable metal material, and FIG. 2 is a schematic explanatory diagram showing an electron beam irradiation state.

Claims (1)

[Claims] A sublimable metal material used when performing vapor deposition plating using an electron beam heating method, with an average particle size of 3 to 50 m.
A sublimable metal material for vapor deposition, characterized in that it is in the form of particles or lumps of m.