JPS6289872A - Formation of solid film by deposition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention uses the so-called chemical vapor deposition method (CVD) in which a solid film is deposited and formed on the surface of a substrate by heating and activating a reactive gas with a thermionic emission member. ).

[Conventional technology]

Conventional 1 For example, in manufacturing carbide tools such as cutting tools and wear-resistant tools, artificial diamond, titanium carbide-nitride titanium, carbonitride titanium, titanium carbonate, and acid hyaluminum are used on the substrate surface. The above-mentioned chemical vapor deposition method is used to precipitate hard coatings such as - For example, to explain the deposition formation of an artificial diamond coating, as shown in the schematic cross-sectional view in FIG. A reactive gas mainly composed of carbon (arsenic and hydrogen) flows into the quartz reaction vessel 1 from a reactive gas introduction pipe 2 opened at the upper part of the reaction vessel 1, and is passed through a filament 3 made of, for example, metal tungsten as a thermionic emitting member. The filament 3 is caused to flow downward through the periphery of the substrate 5 supported on the white root 4, while maintaining the atmospheric pressure in the reaction vessel 1 at 01 to 3 Q Q torr, and using the electric power supplied from the AC power supply section 6 to Heat to 1500-2500°C,
300 to 13 on the substrate surface arranged at a predetermined distance from the filament 3.
The substrate is heated to a temperature within the range of 00° C., and in this state, a desired diamond coating reaction is caused to occur for a predetermined period of time, thereby depositing and forming a diamond coating on the surface of the substrate 5.

[Problem that the invention seeks to solve]

In this method of forming a solid film, the crystallinity of the deposited film is poor, and the crystallinity easily fluctuates and lacks reproducibility.
In a cutting tool coated with a hard coating as described above, if this coating has poor crystallinity, the coating is likely to peel off or the workpiece material will be welded during cutting, making it difficult to stably produce a product with the desired quality. The problem was that I couldn't get it.

[Findings based on research]

Therefore, the inventors of the present invention have conducted various studies to solve such problems.

(1) The reason why the crystallinity of the precipitated film (hereinafter also referred to as the vapor deposited film) is not constant is due to the fact that the emission state of thermionic electrons emitted from the thermionic electron emitting member is not stable. As shown in FIG. 6 above, this thermionic emission state occurs because the thermionic radiation member is directly connected to the AC power source and is therefore directly influenced by the AC power source. For example, when the voltage applied to both ends of the thermionic emission member changes due to this electric part, the emission state of thermionic electrons changes accordingly.

(2) In the method for depositing a vapor deposited film as described above, p? ! When the thermionic electrons ejected from the electron emitting member arrive at the base (2), a current flows between the thermionic emitting member and the base, and this state corresponds to a state in which a DC bias voltage is applied to the P electron emitting member. Such an apparent voltage varies depending on the AC voltage applied to the thermionic emission member and influences the above-mentioned thermionic emission state, but if the thermionic emission member and the AC power supply are connected through one transformer, , and if a tap is taken on the winding on the thermionic emission member side of this transformer and this tap is grounded, the above-mentioned pass-as voltage is stabilized, and as a result, the thermionic emission state is stabilized.

[Means for solving problems]

This invention was invented based on the above-mentioned knowledge, and in the process of emitting thermionic electrons from the thermionic emitting member toward the substrate using the electric power supplied from the AC power source, deposits are deposited on the surface of the substrate. In order to stably maintain the crystallinity of the solid film formed in a good state, a thermionic emission member provided in a reaction vessel into which a reactive gas flows is connected to this thermionic emission member. heating with electric power supplied from an alternating current power supply unit, heating and activating the reactive gas, and heating a substrate placed in the reaction vessel at a predetermined distance from the thermionic emission member. In the method for depositing a solid film, which comprises depositing and adhering a solid material generated based on the reaction of the reactive gas on the surface of the substrate, the thermionic emitting member and the AC power source are , and is characterized in that it is connected via a transformer, and a tap provided on the winding of the thermionic radiation member side circuit of this transformer is grounded.

[Detailed description of the invention]

The method of this invention is as shown in FIG.

A transformer 7 is installed between the AC power source 6 and the thermionic radiation member 3.
11) is characterized in that the tap 8 drawn out from the winding 7a is grounded, and by such means the apparent bias voltage applied to the thermionic emission member 3 is stabilized.
At this time, when a tap 8 is attached to one end of the winding 7a to lower one end of the thermionic emission member 3 to ground potential, as shown by 8' in the figure, an applied voltage is applied to the other end, and the thermionic emission is emitted. Whereas there is no potential difference between the ground portion of the member 3 and the base 5, which is originally kept at ground potential.

The alternating current voltage applied between the other end of the thermionic emission member 3 and the base 5 is the same.However, the non-uniformity of the alternating current voltage applied to the thermionic emission member becomes noticeable, whereas at 8" in the figure As shown, when the tap 8 is placed in the center of the transformer winding 7a and grounded, the center of the thermionic emission member becomes at ground potential, and the applied voltage is applied to both ends of the thermionic emission member 3. The above-mentioned situation in which half the voltage is applied alternately in the positive and negative directions and the voltage is biased and applied to the thermionic emission member 3 is avoided, and the potential difference between the thermionic emission member 3 and the base 5 is relatively Since the tap 8 is evenly leveled, it is preferable that the tap 8 be attached as close to the center of the winding 7a as possible, and the center is most preferable.

[Examples and effects based on the examples]

Next, the present invention will be explained using the formation of a diamond coating as an example and comparing it with a comparative example.

In the apparatus shown in Fig. 1, 1 reaction vessel 1: outer diameter 50
Quartz reaction vessel with throat, thermionic emission member 3: Metallic tungsten filament-substrate 5: 10 mm x 10
Metal tungsten plate with dimensions mm x 10, distance between filament 3 and surface of substrate 5: 30 m, transformer 7:
- Capacity where the voltage ratio between the next side and the secondary side is 1:1 @ 10
KVA transformer, the tap position is at the center of the secondary winding, and the reaction conditions are set as shown in Table 1.
An artificial die coating was deposited on the surface of the tungsten plate 5 by chemical vapor deposition, and for comparison, the transformer 7 was not operated, that is, the transformer 7 was bypassed to allow current to flow. A diamond deposited film of the present invention and a conventional diamond deposited film were respectively formed by coating a diamond deposited film on a tungsten plate using the same method and conditions as described above.

Next, in order to investigate the crystalline state of these diamond deposited films, we used a scanning electron microscope, a microscope, and a photograph of each film part magnified 5000 times, and also obtained the Raman spectra of each film sample using Raman analysis. Ta.

When comparing FIG. 2, which shows the crystalline state of the diamond coating of the present invention with the above-mentioned photograph, and FIG. 3, which shows the crystalline state of the conventional diamond coating with the above-mentioned photograph, FIG. 2 clearly shows the crystal planes unique to diamond. On the other hand, no such crystal planes are seen in Figure 3, and Figure 4, which shows the Raman spectrum of the diamond coating sample of the present invention, shows a sharp peak near 1330ci-1, which is characteristic of diamond crystals. On the other hand, such a peak is not seen in Figure 5, which shows the Raman spectrum of the conventional diamond coating sample, indicating that the diamond coating of the present invention has better crystallinity than the conventional diamond coating. It can be seen that it contains a large amount of crystals with improved crystallinity.

〔Effect of the invention〕

As is clear from the above explanation, according to the present invention, a deposited film with excellent crystallinity can be deposited and formed on a substrate in a stable state by stabilizing the emission state of thermionic electrons, thereby improving quality. It is possible to provide various parts 1, such as indexable tips, miniature drills, end mills, etc., coated with excellent solid coatings with good reproducibility, and it has an industrially useful effect of improving the quality and performance of these parts. can get.

[Brief explanation of drawings]

Figure 1 is a schematic diagram for explaining the invention in detail;
3 and 3 are scanning micrographs of the diamond deposited film, FIGS. 4 and 5 are Raman spectra, and FIG. 6 is a schematic diagram for explaining the conventional method. In the figure, 1...reaction container, 2...reactive gas introduction tube. 3... Thermionic emission member, 4... Base plate. 5...Base body, 6...AC power supply section. 7...Transformer, 8...Tap.

Claims (1)

[Claims] (1) A thermionic emission member provided in the reaction vessel into which the reactive gas flows is heated by electric power supplied from an AC power supply unit connected to the thermionic emission member, and the reactive gas is heated. At the same time as being activated by heating, by heating the substrate placed in the reaction vessel at a predetermined distance from the thermionic emission member, the surface of the substrate is heated to generate a chemical reaction based on the reaction of the reactive gas. In a method for forming a solid film by depositing a generated solid material, the thermionic emission member and the AC power source are connected via a transformer, and the thermionic emission of the transformer is The method for depositing and forming a solid film as described above, characterized in that a tap provided on the winding of the circuit on the member side is grounded.