JPH03249169A - Formation of hard film - Google Patents

Abstract

PURPOSE:To form a hard film having a good adhesive property over a long period of time by cleaning a substrate surface by a glow discharge in a vacuum vessel and then irradiating a ceramics target with a laser beam to evaporate the target and to deposit the film by evaporation on the substrate surface. CONSTITUTION:A working gas, such as Ar, is introduced into the vacuum vessel 1 and the vessel, is evacuated by suction farce from a discharge port 2. While a substrate holder 4 mounted with the substrate 6 is rotated by a motor 5, a negative bias voltage is impressed to the substrate 6. The surface of the above-mentioned substrate 6 is cleaned by generating the glow discharge in this way. The vacuum degree in the vacuum vessel 1 is then increased and the target 8 consisting of a ceramics sintered body disposed therein is irradiated with the laser beam 9 via reflecting mirrors 11, 13. The evaporating particles of the above-mentioned ceramics are excited by the high-frequency discharge of a high-frequency coil 15 and are accelerated toward the substrate 6 so as to be deposited by evaporation on the substrate 6 surface. The hard film consisting of the ceramics which can maintain the adhesive property over a long period of time is formed at a high film forming speed to a prescribed thickness on the substrate 6 surface in this way.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Field of Application) The present invention relates to a method for forming a hard film, and in particular, irradiates a ceramic sintered body with a laser beam and ionizes the ionized ceramic evaporated particles onto a metal member. The present invention relates to a method for forming a hard film by vapor depositing it on a surface to form a film.

(Prior art) Conventionally, in order to improve the wear resistance, heat resistance, or corrosion resistance of rotating shafts made of steel or non-ferrous metal materials, it has been known to cover the sliding parts with a hard coating such as ceramics. It is being

Typical methods include ceramic spraying using a plasma heat source, physical vapor deposition (PVD), and chemical vapor deposition (CVD). The ceramic spraying method is a method in which ceramic grains are melted and the molten ceramic is deposited by colliding with a metal surface using a heat flow such as a high-temperature gas as a medium. This method allows relatively thick layers to be formed. Additionally, in the PVD method, evaporated metal atoms collide with a substrate in an accelerated state to form a thin film, while in the CVD method, a thin film is formed through a chemical reaction with a working gas filled in a container. It is. The coatings formed by these methods form dense layers and are often applied to places where wear resistance is required, such as sliding parts of tools and mechanical parts.

However, although the ceramic spraying method described above allows the layer thickness to be increased, it is difficult to form a dense coating layer, and it is not possible to ensure sufficient adhesion strength to the substrate. Therefore, there is a problem that peeling between the substrate and the coating tends to occur.

On the other hand, the PVD method and the CVD method have problems in the manufacturing process such that the film formation rate is slow, a thin film cannot be formed, and if the film layer is made thick, there is a risk that peeling may occur within the layer. Furthermore, depending on the operating conditions of the sputtering device, columnar crystals are likely to occur, which poses a problem in corrosion resistance.

In order to solve these problems, we irradiate the metal surface to be processed with laser light to form an alloy layer, supply a boriding agent to the surface, and then irradiate it with laser light again to form a hardened layer on the metal surface. A physical vapor deposition method using laser light has been proposed (
(See Japanese Patent Application Laid-Open No. 110851/1983). This physical vapor deposition method using laser light allows the film formed to have a dense structure without pores.

(Problem to be solved by the invention) However, the adhesion strength between the coating layer formed by the above method and the substrate is hardly improved, and wear resistance is required for a long period of time, such as mechanical parts used in power generation plants. There is a problem that it cannot be applied sufficiently to areas where

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the problems of the above-mentioned conventional techniques, to form a ceramic coating layer on a metal surface to a predetermined thickness, and to maintain adhesion to a substrate for a long period of time. It is an object of the present invention to provide a method for forming a hard film by which a film can be formed.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the present invention introduces a working gas into a vacuum container to form a vacuum state, and applies a negative bias voltage to a substrate mounted in the vacuum container. is applied to generate a glow discharge, and the surface of the substrate is cleaned by this glow discharge, and the degree of vacuum in the vacuum container is increased, and a laser beam is applied to a ceramic target provided in the vacuum container. This method is characterized by comprising a film forming step of irradiating the substrate to generate evaporated particles of the ceramic, and depositing the evaporated ceramic particles on the surface of the substrate to form a hard film.

Further, the method is characterized in that the evaporated particles of the ceramic are deposited on the surface of the substrate while being excited by a high frequency discharge means provided in the vacuum container.

(Function) According to the present invention, a working gas is introduced into a vacuum container to form a vacuum state, and a negative bias voltage is applied to a substrate mounted in the vacuum container to generate a glow discharge. The surface of the substrate is cleaned by this glow discharge, and then the degree of vacuum in the vacuum container is increased, and a laser beam is irradiated onto a ceramic target provided in the vacuum container to generate evaporated particles of the ceramic. The evaporated particles of the ceramic are then deposited on the surface of the substrate to form a hard coating, which not only ensures sufficient adhesion strength between the substrate and the coating, but also forms a dense and thick hard coating. be able to.

Further, by depositing the evaporated particles of the ceramic on the substrate surface while being excited by the high-frequency discharge means provided in the vacuum container, the ionization of the evaporated particles can be promoted and the rate of formation of the hard coating can be increased. be able to.

(Example) An example of the hard film forming method according to the present invention will be described below with reference to FIG.

FIG. 1 shows an embodiment of a vacuum evaporation apparatus using laser light for realizing the hard film forming method according to the present invention. Reference numeral 1 in the figure indicates a vacuum vessel for vacuum evaporation, and a working gas such as argon or nitrogen gas can be introduced into the vacuum vessel 1 from a gas inlet (not shown). Further, an exhaust port 2 is formed at the end of the vacuum container 1, and the exhaust port 2 is connected to an exhaust pipe so that the vacuum container 1 can communicate with a vacuum pump (not shown) via the exhaust pipe. It has become.

On the other hand, a rotary shaft 3 is fitted into the center of the vacuum container 1 in a sealed state. A substrate holder 4 is fixed to an end of the rotating shaft 3 inside the container 1, and a motor 5 is installed outside the container 1 at the other end. The motor 5 can rotate the substrate holder 4 at a predetermined speed.

A negative DC high voltage is applied to this substrate holder 4, and a substrate 6 made of aluminum alloy or the like is mounted on the surface thereof. A coil-shaped heater 7 is placed around the substrate 6, and is capable of heating the substrate 6 to a predetermined temperature. Further, a target 8 is mounted at a position facing the substrate 6. This target 8 is designed to be irradiated with a laser beam 9 guided from the outside of the vacuum vessel 1, and is made of a sintered ceramic body and has a cylindrical shape rotatable around a rotation axis 10.

Here, the path through which the laser beam 9 reaches the target 8 will be explained.

First, a laser beam 9 outputted from a laser oscillator (not shown) is reflected by a first reflecting mirror 11 outside the vacuum vessel 1, and then enters a second reflecting mirror 13 inside the vacuum vessel 1 through an aperture 12. The reflected light from the second reflecting mirror 13 can irradiate the surface of the target 8 in the tangential direction.

The aperture 12 is a window that can maintain the vacuum of the container 1 and does not impair the orthogonality of the laser beam 9, and is made of Zn5e or KCl. Further, the second reflecting mirror 13 is mounted so as to be movable in the direction of the arrow as shown in FIG. 1 so that the incident angle of the laser beam 9 always coincides with the tangential direction of the target 8. In this embodiment, the second reflecting mirror 13 is movable on a rail 14. By making the incident angle of the laser beam 9 equal to the tangential direction of the target 8 in this way, the evaporated particles of the ceramic caused by the irradiation of the laser beam 9 can always be reflected and diffused in the normal direction of the target 8. The substrate 6 is mounted in the direction of diffusion of the evaporated particles. Further, a high frequency coil 15 is arranged between the target 8 and the substrate 6. This high frequency coil 1
5 is used for cleaning the substrate surface and promoting ionization of evaporated particles from the target 8, and is connected to a high frequency generation source 16 located outside the vacuum chamber 1.

In order to prevent the vacuum vessel 1 from being affected by the irradiation of the laser beam 9, a heat shield plate 17 is provided on the side surface of the vacuum vessel 1, and a reflection protection plate 18 is provided behind the second reflecting mirror 13. .

Next, a process of forming a hard coating on an alloy substrate using the vacuum evaporation apparatus configured as described above will be described.

First, an aluminum alloy is mounted on the substrate 6 in the vacuum vessel 1, and an alumina sintered body that will become the target 8 is rotatably mounted at a predetermined position.

Thereafter, the vacuum vessel 1 is heated by a heating means (not shown) and the pressure is reduced to 10 -4 to 10' Torr via an exhaust port by a vacuum pump (not shown). Then, a working gas such as argon or nitrogen gas is introduced from a gas inlet (not shown) to bring the pressure inside the container to 10 to 10' Torr.

In this state, glow discharge is generated in the vacuum container 1 by applying the direct current power source and the high frequency generation source (3) above. Due to this glow discharge, the argon or nitrogen atoms in the working gas are ionized and Ar
Ions and the like are attracted to and collide with the substrate 6 to which a negative bias voltage is applied, thereby cleaning the substrate surface (this cleaning action is called bombardment). In this example, the bombardment process is performed for about 20 minutes.

Next, the vacuum container is further evacuated from the above-mentioned state, and the pressure inside the container is set to 10' to 10-5 Torr.

In this state, the target 8 in the vacuum vessel 1 is irradiated with a CO2 continuous wave laser. The laser beam 9 reaches the surface of the ceramic target 8 through the above-described path. At this time, the target 8 is preheated by a heater (not shown) in order to prevent a rapid temperature rise due to the irradiation of the laser beam 9, and is rotated so that only the - point does not melt.

Moreover, the evaporated particles passing through the high-frequency coil 15 are excited by the action of the high-frequency coil 15, and ionization of the evaporated particles can be promoted.

In this embodiment, the output of the laser beam 9 is soow,
Irradiation was performed for about 20 minutes. Further, the rotation speed of the target 8 is set to 50 rpm, and the moving speed of the second reflecting mirror 13 is set to 2 mm/min.

Note that as a pretreatment step for the cleaning and film-forming steps described above, the surface of the substrate 6 may be plated with a metal that has an affinity for the vapor-deposited ceramics to improve the adhesion between the vapor-deposited film and the substrate.

Furthermore, the substrate metal used in the above-mentioned embodiments is not limited to aluminum alloy, but can also be applied to various ferrous and non-ferrous metals.In addition to alumina, the ceramic material used as the coating may include mullite, silicon nitride, Boron nitride or the like can be used.

Next, the strength properties of the hard coating formed on the substrate surface according to the present invention will be explained.

FIG. 2 schematically shows a cross section of a substrate on which a hard coating is formed according to this example. This board 6 has a diameter of 80 mm,
It is a disc-shaped aluminum alloy with a thickness of 10 mm, and an alumina vapor-deposited film 19 with a film thickness Δt is formed on its surface. This coating has a maximum roughness Rm as shown in Figure 3.
It is formed on a smooth coating surface with ax-1.6μ■ and average roughness Ra=0.12μ■, and the coating structure is densely structured.

According to the results of X-ray diffraction, this coating structure exhibits a wide spectrum, indicating that amorphous alumina is formed. In addition, the surface hardness of this coating is Vickers hardness Hv140.
0 to 1600 can be obtained, and the adhesion strength between the aluminum substrate and the coating can be secured to be about 5 to 6 kg/s.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, a negative bias voltage is applied to a substrate in a vacuum chamber filled with a working gas to generate glow discharge to clean the substrate surface, and then, By increasing the degree of vacuum in the vacuum chamber and irradiating the ceramic target with laser light to generate evaporated particles, a hard film is formed on the surface of the substrate, ensuring sufficient adhesion strength between the substrate and the film. At the same time, it is possible to form a dense and thick hard film, which has the effect of improving the abrasion resistance and heat resistance of metal parts, and also to excite the evaporated particles using high frequency discharge means. Since it is vapor-deposited on the surface, effects such as increasing the deposition rate of the hard coating and improving the productivity of products on which the hard coating is formed can be expected.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of the vacuum evaporation apparatus used in the present invention, FIG. 2 is a schematic cross-sectional view of a substrate on which a hard coating is formed according to the present invention, and FIG. FIG. 3 is a diagram showing the measurement results of the surface roughness of the formed hard coating. 1... Vacuum container, 2... Exhaust port, 3... Rotating shaft,
4... Board holder, 5... Motor, 6... Board,
7... Heater, 8... Target, 9... Laser light, 11... First reflecting mirror, 12... Aperture,
13... Second reflecting mirror, 15... High frequency coil.

Claims (2)

[Claims] 1. A working gas is introduced into the vacuum container to create a vacuum state, a negative bias voltage is applied to the substrate mounted in the vacuum container to generate glow discharge, and the glow discharge cleans the surface of the substrate. The degree of vacuum in the vacuum container is increased, and a laser beam is irradiated to a ceramic target provided in the vacuum container to generate evaporated particles of the ceramic, and the evaporated particles of the ceramic are A method for forming a hard film, comprising a film forming step of forming a hard film by vapor deposition on the surface of a substrate. 2. 2. The hard film forming method according to claim 1, wherein the evaporated particles of the ceramic are deposited on the surface of the substrate while being excited by a high frequency discharge means provided in the vacuum container.