JPS62185881A - Ion surface treatment - Google Patents

Abstract

PURPOSE:To uniformly and efficiently form a surface treatment layer on an article to be treated by uniformly diffusing and supplying a gaseous material between the article to be treated and auxiliary electrodes so that the gaseous material is immediately brought into reaction in a glow discharge area of a high electrolytic dissociation density. CONSTITUTION:The treating gas contributing to the reaction is ejected to the article 2 to be treated while gas supply pipes 17 having gas ejection ports 22 are moved by a motor 21 in the space between the article 2 as a cathode and the auxiliary electrodes 5a, 5b connected thereto. The article 2 is subjected to the treatment while the article 2 or the article and the auxiliary electrodes 5a, 5b are rotated in the direction opposite from the supply pipes 17 or moved back and forth by which the treatment layer is made uniform. The supply pipes 17 have perferably plural pieces of the gas ejection ports 22 having the bores larger nearer the top end or the supply pipes 17 have preferably plural pieces of the ejection ports 22 having the spacings smaller nearer the top end.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a method of surface treatment of a member by glow discharge.
The present invention relates to an ion surface treatment method that can uniformly distribute a reactive gas on the surface of a workpiece to obtain a treated layer with less unevenness.

[Background of the invention]

2. Description of the Related Art A surface treatment method using glow discharge, which is a type of surface treatment technique for parts, such as metal parts, has recently been in the spotlight. A typical example is ion nitriding (Masanobu Fukazawa: Metal materials; vol-15, A7, p4
3-46).

As shown in Fig. 2, the ion nitriding method uses at least 1
A workpiece 2 to be processed is held by a hanging tool 3 in a sealed container 1 whose pressure is reduced to 0 Torr or less, and a DC power source 4 is connected with the sealed container 1 as an anode (the container may be used as a cathode) and the workpiece 2 as a cathode. The surface of the member to be processed 2 is hardened by applying a voltage thereto to generate a glow discharge while introducing a gas substance necessary for processing into the sealed container 1 from the supply port 19. Such a sealed container 1 has a water-cooled structure to prevent various devices and parts from being overheated due to heating by glow discharge.

When performing the ion nitriding process, the vacuum pump 6 is operated to reduce the pressure inside the sealed container 1 to at least 10-' Torr, while hydrogen and nitrogen gas, or ammonia gas (
NH, ), etc. are introduced into the sealed container 1 through the gas supply port 19 and maintained at a pressure of 0.1 to 10 Torr, and a voltage of 300 to 1500 V is applied from the DC power supply 4 to the anode terminal 7 and the cathode terminal 8. Glow emission t is generated by applying the voltage between the two.

In addition, in Figure 2, 12 is gas? 10 is an optical pyrometer, and 11 is a vacuum gauge.

On the other hand, recently, CVD has been used as surface treatment using glow discharge.
The law is being actively developed. This CVT) method is -
For example, it is used to coat metal surfaces with TIC. In this TIC coating, the workpiece to be treated is held in a sealed container l, the pressure is reduced to IQ Torr, and then TiC
The processing gases of l4 and C2H2 are combined with carrier gas (Ar+5
%H2) into a sealed container to coat the surface of the member to be treated with TIC.

FIG. 3 is an explanatory diagram showing an example of a conventional CVD apparatus, in which a member to be processed 2 is held in a sealed container 1, the member to be processed 2 is used as a cathode, and the sealed container 1 itself is used as an anode. Then, the pressure inside the sealed container 1 is reduced via a vacuum pump (not shown), and the carrier gas 12 & (Ar + H2) is
TiCA 4 is passed through the container 14 containing the TiCA 4 and vaporized, and introduced into the sealed container 1 together with the Ar + H 2 gas 12b. On the other hand, C2H2 is introduced into the sealed container 1 from the C2H2 source 126, and υ voltage is applied to the power source 4 to generate a discharge, thereby coating the surface of the member 2 to be treated with TIC.

At this time, the member 2 to be processed is heated by the glow discharge energy generated on the surface, so no external heat source is required. Therefore, the temperature of the member to be processed changes by degrees Celsius depending on the ratio of the surface area to the volume of the member to be processed. On the other hand, in order to form a uniform coating layer, it is necessary to make the glow discharge generated on the surface of the object to be treated uniform. However, in the conventional CVD method, the shape of the object to be treated is relatively simple. Although it is possible to generate a uniform glow discharge in some cases,
In the case of a workpiece having a complicated shape, the ion bombardment energy and the ionization density of the processing gas change in the surface portions having different relative distances from the anode, making it impossible to uniformly treat the surface. This is due to variations in the concentration of atoms trapped on the surface of the workpiece, which results in different coating speeds. Therefore, it is almost impossible to form a film on the concave surface of a workpiece with large irregularities.In particular, glow discharge surface treatment, such as carburizing, boring, etc., or CVD method, which requires a high temperature range of 700 to 1200°C, can hardly form a film. There is a problem in that the voltage is high, and as a result, the discharge becomes non-uniform, resulting in a temperature difference, which increases the tendency that uniform surface treatment cannot be performed on the object to be treated. As a solution, there are, for example, a method of performing ion treatment in a conventional vacuum heat treatment furnace, or a method of performing ion treatment while applying high frequency heating from the outside. However, in the former case, the object to be processed is heated using a heater such as carbon fiber, so the heating power source requires high output, and the amount of heating by ions is reduced, so conventional processing using only ions is not possible. In comparison, the amount of ions reaching the surface of the object to be treated is also small. Therefore, the structure of the device is complicated, the control is complicated, the overall energy consumption is large, and the concentration of atoms involved in the cleaning action of ions and the processing of atoms trapped on the surface is also reduced.

In the latter case, heating is performed by induced current caused by high frequency, so if many parts are installed in the furnace, the temperature heated between individual parts will differ depending on the distance from the high frequency coil, and as in the former case, the temperature at which the individual parts are heated will differ depending on the distance from the high frequency coil. Controlling the output becomes complicated. In addition, a large amount of energy is required for the treatment, and there are drawbacks in terms of ion cleaning effect and control of surface ion concentration.

On the other hand, by providing an auxiliary electrode near the workpiece in addition to the cathode, which is the workpiece, and using this auxiliary electrode as the cathode and the workpiece as the anode, the surface of the workpiece near the auxiliary electrode can be Processing methods that control temperature are also used. However, these methods require a heating power source in addition to a glow discharge power source, resulting in complicated devices. First of all, the inventor of the present invention installed a plurality of cathodes at a constant interval apart from the cathode, which is the object to be processed, on the outer periphery of the object to be processed and inside a vacuum container. Place and gas pressure during ion treatment,
By controlling the spacing, power output, etc., glow discharge is also generated on this cathode, creating a hollow cathode discharge with high ionization density, thereby heating or holding the surface of the workpiece at a high temperature. We made it clear that we can do it (
Patent No. 1.254,821). This process can be carried out by installing a hollow cathode jig 5 for forming a hollow cathode discharge in the conventional apparatus shown in FIG. 2, as shown in FIG. 4, according to the purpose.

In all of these treatments, it is important to control the plasma gas pressure of glow discharge. Gas pressure control in the conventional ion nitriding apparatus shown in FIGS. 2 and 4 is as follows:
This was done by adjusting the barrier pull leak pulp or by measuring the gas pressure with a vacuum gauge and opening and closing electromagnetic pulp, etc. In addition, since the gas outlet was fixedly installed in a part of the upper part of the furnace body, there was no major problem with nitriding treatment due to the diffusion of nitrogen, etc., but when performing carburizing etc. at a high treatment temperature, , non-uniformity of the hardened layer was observed depending on the location. This is due to the fact that the gas concentration is non-uniform depending on the location. Traditionally, stirring fans have been used as a means to obtain uniform distribution of processing gas.
Since the processing pressure is 0.1 to 10 Torr, it is very difficult to move the gas by rotating a fan.

Therefore, the inventor first attempted to solve the above problem by intermittently or continuously changing the position of the gas outlet above the reduced pressure vessel when introducing the processing gas (Unexamined Japanese Patent Publication No. (1974-9974).

As a result, the effect was remarkable in carburizing treatment, etc., in which elements are diffused from the surface of the treated product. However, in CVD, which forms a film on the surface to be treated, it is difficult to efficiently supply the introduced treatment gas, such as S and % log gas, into the hollow cathode discharge area, and unreacted treatment gas flows into the furnace body. When the furnace body is opened, these substances adhere to the walls and come into contact with the air and absorb moisture. These substances release gas during the next process, creating a gas atmosphere that is harmful to the process and preventing uniform processing. The problem was that I couldn't do it.

[Purpose of the invention]

An object of the present invention is to provide an ionic surface suitable for surface treatment of objects to be treated, particularly for CVD film formation and carburizing treatment that require high temperatures, and capable of uniformly and efficiently forming one or more surface treatment layers. To provide a processing method.

[Summary of the invention]

In the present invention, an article to be treated is used as a cathode in a reduced pressure atmosphere containing a gaseous substance, an auxiliary electrode connected to the cathode is disposed opposite to and near the article to be treated, and the surface is treated by glow discharge. In the ion surface treatment method, while moving a gas supply pipe having a gas jet port in a space between the workpiece and the auxiliary electrode between the workpiece and the auxiliary electrode or between opposing auxiliary electrodes, By supplying the gaseous substance into the space from the outlet, the gaseous substance is uniformly and efficiently supplied into the high ionization density discharge chamber, thereby effectively performing glow discharge treatment.

[Embodiments of the invention]

The ionic surface treatment method using glow discharge, which is the premise of the present invention, imparts functions such as surface hardening, lubricating action, corrosion resistance, or fatigue resistance to the surface of the workpiece by diffusing or precipitating a processing gas onto the workpiece surface. It is something to have. K provides these functions without adversely affecting the mechanical, chemical properties, etc. of the material to be processed.
It is important to appropriately control the amount, depth, thickness, etc. of atoms to be precipitated. Factors that control these include treatment temperature and time during reaction and surface concentration. These controlling factors are the main ones that affect the rate of atomic diffusion, the critical solid solution cap, the crystal structure of precipitates, and the rate of formation.

First, the treatment temperature is generally in the range of 400 to 700°C when surface hardening steel with nitrogen, 700 to 1100°C in case of surface hardening by carburizing, and 800 to 1100°C in case of surface hardening by carburizing. -1200°C, in the case of sulfurization treatment to obtain surface lubrication using sulfur, it is 150-600°C, while in the case of film formation by CVD, it is generally 500-1200°C, although it varies depending on the atoms to be coated on the surface. There are many ranges. Atoms to be diffused or precipitated as described above,
It is necessary to select an appropriate temperature depending on the type of product to be processed.

In the ion surface treatment method, a method using an external heat source can also be used to efficiently raise the surface temperature of the object to be treated or to partially heat it to an appropriate temperature. In the method of the present invention, an auxiliary electrode having almost the same potential as the material to be treated, which serves as a cathode, is placed at a predetermined distance from the surface of the material to be treated and connected to the cathode, and the auxiliary electrode is connected to the material to be treated during ion treatment. Processing is performed by high ionization density discharge by controlling the gas pressure introduced into the space formed by the electrodes.

Here, heat collection from the processed product is achieved through heat exchange of glow discharge energy and radiant heat from the processed product and auxiliary electrodes, while heat loss due to heat release is achieved through radiant heat, convection of processing gas, and heat from the electrodes. These include conduction (flow from the electrode cooling water).

Among these factors, radiant heat between the auxiliary cathode and the workpiece can be used to heat the required part of the workpiece to a predetermined temperature. This makes the cathode spacing constant,
By setting the introduced gas pressure to a predetermined value and causing interaction between the two negative glows, a high ionization density discharge is caused in one negative glow discharge section to heat and keep warm. It is something.

Note that, in the high ionization density discharge, when two negative glow discharges are brought close to each other at a certain distance, interaction occurs between the negative glows, and the ionization density of other glow discharge parts also becomes high. In this region of interaction, the discharge current becomes high. in this case.

The ion density of the gas in the space between the workpiece and the auxiliary electrode is also increased. Therefore, on the surface of the object to be treated, the diffusion or precipitation of carbon, which also has active surface reactions with active atoms, is promoted. In order to make this diffusion and precipitation phenomenon more effective, the distance from the surface of the workpiece to the auxiliary electrode, the gap between the auxiliary cathodes, the material, shape, area, gas pressure, and method of introducing the processing gas must be adjusted appropriately. It is very important to control it.

First, the distance from the surface of the workpiece to the auxiliary electrode or the spacing within the auxiliary cathode varies depending on the gas pressure, but the negative glow generated between the workpiece and the auxiliary electrode may interact in some way to cause high ionization density discharge. If it does not occur, the desired effect will not occur.

The width of the negative glow varies depending on the gas composition and gas pressure.
This is because this strongly influences high ionization density discharge. Furthermore, the auxiliary electrode and negative glow discharge area, which are closely related to these, must also be considered. Therefore, in general ionic surface treatment, if this distance is less than 0.5 m, the reaction of the processing gas to the object to be treated tends to be inhibited, while if the distance is more than 50 u+, the interaction between the glows will be inhibited. The heating effect of the radiant heat from the auxiliary electrode, which has a weak influence, on the workpiece is reduced, and there is also heat loss to the auxiliary electrode, resulting in a loss of energy.

Next, the gas pressure naturally has an appropriate value once the gas composition and the purpose of surface treatment are determined. For example, if the gas composition and the distance between the workpiece and the auxiliary electrode are kept constant, changing the gas pressure will cause a high ionization density discharge within a certain range.
As the current density of the discharge increases, the temperature of the object to be processed also increases, reaching its maximum temperature. If the gas pressure is not appropriate, it tends to lower the temperature of the processed product.

Processing temperature is thus influenced by gas pressure and gas composition. The appropriate gas pressure is 0.0 in absolute vacuum.
A range of 1 to 1 Q Torr is preferred.

Next, the surface concentration, which is one of the important factors in the surface treatment reaction, depends on the gas pressure, gas composition, and gas distribution of the treatment gas introduced. In order to form a surface treatment layer using high ionization density discharge, it is necessary to consider the method of introducing the treatment gas.

The processing gas introduced into the sealed container is sucked by a vacuum pump,
It is diffused by convection of the temperature inside the furnace, gravity, etc. In the conventional ion nitriding treatment equipment shown in FIG. The partial pressure of certain gases fluctuates. In particular, fluctuations in the gas partial pressure of substances involved in the reaction greatly affect the formation of the surface treatment layer.

This will be explained by taking the case of CVD of Tic coating as an example. CVD involves reacting a gaseous substance of a metal compound with a gaseous substance (reactive gas) that reacts with the gaseous substance to form a reactant, and coating the surface of the object to be treated with the reaction product. This reactant is supplied from the atmospheric gas. For example, in TIC coating, TlC14 as a gaseous substance of a metal compound is dispersed in H2 as a carrier gas, and CH4 is used as a gaseous substance (reactive gas) that reacts with the gaseous substance of the metal compound to form a reactant. , when TIC is formed by changing the partial pressure (composition) of TiC2 and CH4, depending on the ratio of partial pressures (composition), TIC
+Tl *T1xC1, -x, a film of TIC 10 is formed. Therefore, to form a TXC film with a stoichiometry in which X of TlxCl-〇 is 0.5, T i C1
It is necessary to accurately control the partial pressure (composition) of CH4 and CH4. This partial pressure is controlled by controlling the vaporization temperature and pressure of TiCH4, the flow rate of H2 as a carrier gas, and the flow rate of CH4 as a reaction gas. This flow rate can be easily controlled by using a mass flow meter or the like. However, even if the flow rates are maintained accurately and the partial pressures are controlled in this way, the partial pressures (compositions) of the 'rtcz4 and CH4 processing gases will vary depending on the position of the workpiece when introduced into the furnace. There is.

This tends to cause fluctuations due to the flow caused by the diffusion of the processing gas, the suction of the vacuum evacuation device, and the flow caused by the convection of the temperature inside the furnace. Furthermore, TiC, which is a gaseous substance of a metal compound,
H4 is consumed by thermal decomposition or adsorption to the cooled furnace wall, resulting in a change in the supplied partial pressure. As a result, either no TiC is formed on the surface of the workpiece, or even if TiC is formed, it is difficult to uniformly form TiC with the desired stoichiometry on multiple workpieces at different positions. For this reason, it is necessary to control the gas partial pressure to reduce fluctuations.In other words, the partial pressure of the gaseous substance of the metal compound is extremely low, in other words, an extremely small amount of gas is supplied. It is necessary to pass this very small amount of gas through the gap between the auxiliary electrode and the workpiece to uniformly distribute the new gas substance on the surface of the workpiece.In addition, gaseous substances or reactants must be introduced into this gap. It is necessary to immediately adhere to the surface of the product to be treated without stagnation.

Therefore, in order to uniformly form a film with the target composition, a reactive gas adjusted to an appropriate equivalence ratio is supplied through a gas supply pipe to the object to be treated and the auxiliary electrode, or to the space between the auxiliary electrodes. It is necessary to cause the reactive gas to react by generating a glow discharge with a high electric density, and to distribute the reactive gas uniformly so that the composition of the film is homogeneous and uniform.

For this purpose, the reactive gas supply pipes and/or the article to be treated are moved. For example, the reactive gas supply pipe is rotated or reciprocated to change its position intermittently or continuously. Similarly, when moving both the article to be treated and the reaction gas supply pipe, the article to be treated is also moved relatively.

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows an example of a surface treatment apparatus used to carry out the present invention. In the figure, 1 is a furnace body, and an upper cover and a lower cover are inserted into the upper and lower openings of the hollow cylindrical body. It is fixed and sealed through the. Reference numeral 2 denotes an article to be processed which becomes a cathode, and is held by a rotating holding member 3 connected to a rotating cathode terminal 8. The other end of this rotating cathode terminal 8 is connected to the cathode of the power source 4 via a rotating power supply mechanism 9. Further, the rotation holding member 3 is designed to be rotated many times by the rotary electric motor 21. Near the workpiece 2 are inner and outer cylindrical auxiliary electrodes 5m.

5b, one end of which is connected to the cathode side. On the other hand, one end of the furnace body 1 is connected to an anode 7 of a power source 4.

The reactive gas supply means has the following configuration.

The flow rate of the carrier gas 12m is controlled by the flow rate control system 13, and the T I CH4 is passed through the container 15 containing the T I CH4.
While CH4 is vaporized, the flow rate of the reaction gas 12b is controlled by the flow rate control system 13, and both of these gases are fed from the cathode and anode through a gas rotating supply machine $416 insulated by the insulator 18. The gas is introduced into the gas supply pipe 17 inside the furnace body l.゛The gas supply pipe 17 connects the product to be treated 2 and the auxiliary electrode 5m.
, 5b. This gas supply pipe 1
7 is rotating gas supply ml! 16 receives rotational motion from the rotary conductive machine 21 and rotates.

Item to be processed 2. Examples of detailed configurations of the auxiliary electrodes 5m, 5b and the gas supply pipe 17 are shown in FIGS. 5, 6, and 7.

Figure 5 shows cylindrical auxiliary electrodes 5 m, 5
A perspective view showing an example in which the gas supply pipe 17 is located on the circumferential orbit between the object to be processed 2 and the auxiliary electrodes 5m and 5b. It is a diagram. In the figure, in the cylindrical auxiliary electrodes 5m and 5b, the inner circumferential surface of the auxiliary electrode 5a and the outer circumferential surface of the auxiliary electrode 5b face each other in a concentric circle, and a pin-shaped workpiece 2 is placed on the concentric circle between them. Further, a plurality of branched gas supply pipes 17 are disposed on a concentric circle between the inner circumferential surface of the auxiliary electrode 5a and the article 2 to be treated, and between the outer circumferential surface of the auxiliary electrode 5b and the article 2 to be treated. Workpiece 2 and auxiliary electrode 5m.

One end of 5b is connected to the cathode of the power source. Processing gas is supplied to the gas supply pipe 17 by the mechanism shown in FIG. Processing gas is ejected.

Figure 6 shows an electrode structure in which disc-shaped auxiliary electrodes 5m and 5b are opposed to each other, a workpiece to be processed is connected to the auxiliary electrodes, and a gas supply pipe 17 is arranged between the disc-shaped auxiliary electrodes. This is an example of a supply structure. In the figure, two disc-shaped auxiliary electrodes 5
a and 5b are installed in parallel and facing each other with a constant gap maintained. The workpiece 2 is placed on one or both surfaces of the opposing planes of these auxiliary electrodes. A gas supply pipe 17 branched radially into a plurality of radially arranged gas supply pipes 17 is arranged in the space between the article 2 to be processed and the auxiliary electrodes 5m and 5b arranged in this way. rotating feeder sll
? : Rotate around. This plurality of branched gas supply pipes 17
A plurality of gas jet ports 22 are provided. Note that when the article 2 to be treated is placed on the auxiliary electrode, it is connected to the cathode of the stain source.

In addition, one end of the plurality of auxiliary electrodes 5m and 5b is connected to the cathode of the power source, and in some cases, the plurality of auxiliary electrodes 5m and 5b are connected to the cathode of the power source.
Either electrodes m and 5b rotate relative to each other, or one of the plurality of auxiliary electrodes 5m and 5b rotates, or moreover, the plurality of auxiliary electrodes 5m and 5b rotate simultaneously.

FIG. 7 shows flat plate-shaped auxiliary electrodes 5m and 5b facing each other,
FIG. 2 is a perspective view showing an example in which the article to be processed 2 is installed on the auxiliary electrode and the gas supply pipe 17 is arranged in the space between the flat plate-shaped auxiliary electrodes sa and sb. In the figure, a flat object 2 to be treated is connected to the cathode of the stain source by being placed on one or both opposing sides of flat auxiliary electrodes 5m and 5b. The gas supply pipe 17 reciprocates over a range larger than the processing range of the workpiece 2 installed on the flat plate-shaped auxiliary electrode, and ejects reactive gas from a plurality of gas ejection ports 22 provided therein. On the other hand, the flat plate-shaped auxiliary electrodes 5m and 5b also reciprocate relative to each other, singly, or simultaneously, as described above.

In this way, while moving the gas supply pipe 17, the processing gas is ejected from the gas outlet 22 onto the workpiece 2, and more preferably the workpiece 2, or the auxiliary electrode 5 on which the workpiece 2 is installed, When K is processed by rotating or reciprocating the opposing auxiliary electrodes 5, the K-treated layer can be made uniform. In addition, because the reactive gas is supplied only between the auxiliary electrodes or between the auxiliary electrode and the workpiece, the supplied reactive gas reacts quickly in this space and forms a treatment layer on the surface of the workpiece. do. Therefore, efficient processing is possible, and there is also the advantage that there is less diffusion of unreacted gas into the furnace.

Here, in order to make the thickness of the film formed on the object to be processed uniform, it is preferable to control the distribution state of the reaction gas. The distribution state of the reaction gas changes depending on the size and distribution of a plurality of gas jet ports provided in the single or plural branched gas supply pipe 17.

Control of the distribution state of the reactant gas will be explained by taking as an example a configuration in which the object to be processed and the gas supply pipe are arranged between the disc-shaped auxiliary electrodes as shown in FIG.

FIG. 8 shows the distribution range of the reaction gas obtained in each of the four gas supply pipes 17 when a plurality of gas jet ports having the same diameter are arranged at the same intervals in each of the four gas supply pipes. FIG. 9 shows the relationship between the position in the longitudinal direction of the gas supply pipe in FIG. 8, the amount of reactant gas, and the thickness of the coating. As shown in FIGS. 8 and 9, when the spacing and size of the gas jet ports are the same, when the reaction gas is supplied from the center, the position of the center is higher than that of the tip of the gas supply pipe. The distribution is such that a larger amount of reactant gas is supplied at the position.

As a result, the thickness of the formed coating on the processed object is thin at the tip of the gas supply pipe and thick at the center, making it difficult to obtain a uniform distribution over a wide range within the auxiliary electrode. Have difficulty. Therefore, in order to obtain a uniform distribution of coating thickness, it is necessary to have the distribution range of the reactive gas as shown in Figure 10 using the same electrode structure and gas supply system as in Figure 8. . FIG. 11 shows the relationship between the longitudinal position of the gas supply pipe, the amount of reactant gas, and the thickness of the coating in FIG. 1O. As shown in Figures 10 and 11, the amount of reactive gas should be larger at the tip than at the center of the gas supply pipe.1) The distribution range of the reactive gas should be wider at the tip. It is. As a result, the thickness of the formed coating on the processed object is uniform both at the tip and center of the gas supply pipe, and it is possible to obtain a uniform distribution over a wide range within the auxiliary electrode. It becomes possible.

In this way, the amount of reaction gas is increased at the tip of the gas supply pipe.
In order to reduce the amount of gas in the center, it is preferable to control the distribution state and/or the size of a plurality of gas jet ports.

For example, in FIG. 12 (,), the size of the plurality of gas jet ports 22 is kept constant, and the distribution state is controlled by changing the interval between each gas jet port. As the distance increases, the spacing between the gas ejection ports becomes closer, and the distribution becomes more sparse as it gets closer to the center. In addition, in FIG. 13(a), the intervals between the plurality of gas jet ports 220 are constant, and the diameter of each gas jet port is changed. , becoming smaller towards the center. By configuring the gas outlet as described above, the first
As shown in Figure 3 (b), the amount of reactant gas supplied increases as it approaches the tip of the y-s supply pipe, and the thickness of the coating on the processed product also increases on the inner and outer circumferential sides of the auxiliary electrode. Uniform processing becomes possible. The explanation regarding zero or more gas jet ports 22, which can obtain the same effect even if the size and interval of the gas jet ports are changed, is as shown in FIG. use.

Gas is supplied by gas supply pipes installed radially from the center, but in the case of other auxiliary electrode structures, such as the cylindrical or parallel plate shapes shown in Fig. 5 or 7, each auxiliary electrode upon.

By arranging the gas outlet so that the same reaction gas distribution range as above is achieved at the lower position, it is possible to perform treatment with a uniform coating thickness.

Hereinafter, specific examples of the present invention will be described.

<Example 1> Carburization and subsequent TiC coating were performed using the processing apparatus shown in Fig. 1 and the configuration of the auxiliary electrode and gas supply means shown in Fig. 5.
An IS standard 8KD61 hot die copper 61 type aluminum die casting mold bottle (diameter 12 mm, stepped, height 120 m) was used. The auxiliary electrodes 5a and 5b in Fig. 5 have a height of 150 m.
The inner diameter of the auxiliary electrode 5a is 340 m, and the inner diameter of the auxiliary electrode 5b is 340 m.
Both had an outer diameter of 250tI and were made of mild steel with a thickness of 5H. The inner diameter of this auxiliary electrode 5a and the auxiliary electrode 5b
The workpiece 2 is placed at a position with a diameter of 295mm, which is the middle of the outer diameter of the workpiece 2.
25 pins were installed at 24m intervals.

Two gas supply pipes 17 are provided at angles dividing the space between the auxiliary electrodes 5m and 5b and the pins of the workpiece 2 into six equal parts.

A total of 12 were installed. This gas supply pipe has a large number of gas jet ports 22 each having a diameter of 1.0 m in the range of the end portion 130 of the sieve.

The vacuum pump 6 vacuums the inside of the furnace body 1 by 5 x 10-''
Reduce the pressure to below i'orr, and in that state H,,l! A DC voltage of 400 to 900 V was applied to generate a discharge with high ionization density between the workpiece 2 and the auxiliary electrodes 5m and 5b, and after holding the temperature at 1020°C, CH4 gas was introduced. Introduced and held at 2.5 Torr, this allows fi Tie
Carburizing was performed for 5 hours as a pretreatment before coating.

After carburizing, the gas in the container 15 is then
ct4 was vaporized with H2 of the carrier gas 12a, mixed and supplied, and a 50-TIC coating process was performed at 1020°C. In addition, when supplying the processing gas, the gas supply pipe 17 was continuously rotated at a rotation speed of 17 rap-m. Further, the product to be processed 2 and the auxiliary electrodes 5m and 5b are also treated in 5.
The treatment was performed by rotating it in a direction relative to the gas supply pipe 17 using Orap*m.

The treatment was also carried out by the conventional method shown in FIG. 4 using the same steps as above.

As a result, according to the embodiment of the present invention, the Tic coating was formed uniformly in the range of 10 to 12 μm.
The chemical composition ratio of 1 and C was close to 1. Therefore, the process gas is uniformly distributed, and the partial pressure of each gas is also uniform.

On the other hand, in the conventional method, a uniform TiC film was not formed, and the film that was formed was a black soot-like soft layer containing a lot of C. Therefore, either the processing gas effective for forming the TIC film was not supplied to the surface to be processed, or even if it was supplied, the distribution of each gas changed and the TIC film of the desired composition was
It can be seen that no was formed. In addition, unreacted TIC10 and reaction products adhere to the entire surface of the furnace wall, and react with moisture in the air, turning the furnace wall into a sticky hygroscopic substance, and in the next pressure reduction step, the temperature drops to 5 X 10 Torr. The time required to exhaust the air has become extremely long. On the other hand, there are fewer deposits on the furnace wall after treatment according to the embodiment of the present invention, unlike in the conventional method.
Therefore, the effect of efficient film formation within the high ionization density discharge region was clearly confirmed.

<Example 2> Carburizing treatment was performed using the processing apparatus shown in FIG. 1 and the configuration of the auxiliary electrode and gas supply means shown in FIG. 6. (CVD is not performed.) JIS
Standard S CM415 chromium molybdenum steel 20X20
A friend using plate-shaped parts processed to x5mm. As the disk-shaped auxiliary electrode shown in FIG. 6, a disk made of heat-resistant steel with an outer diameter of 360 ism, an inner diameter of 180 m, and a plate thickness of 5 mW was used. Fifty pieces of the workpieces 2 were dispersed on the disk-shaped auxiliary electrode located on the lower side, and were set at a distance of 1711 points from the upper disk-shaped auxiliary electrode. The processing gas supply pipes 17 are adjusted to have a height K midway between the upper disc-shaped auxiliary electrode and the workpiece 2, and are arranged in four radial directions.
It is rotated many times like C. The gas supply pipe 17 has a gas outlet 22.
A plurality of electrodes each having a diameter of 1.5 mm are provided in a 60 area area excluding 15 areas inside and outside the disc-shaped auxiliary electrode.

During the treatment, the inside of the furnace body 1 is heated by the vacuum pump 6.
Exhaust to below X 10-2 Torr, and in that state H2
A gas is introduced and a DC voltage of 400 to 900 V is applied to generate a glow discharge with a high density between the workpiece 2 including the lower auxiliary electrode and the upper disk-shaped auxiliary electrode, 10
Soaking was carried out at 40°C for 5 hours, followed by CH4 gas being introduced and maintained at 4 Torr, followed by 15-carburizing at 1040°C. After carburizing, only H2 gas is heated to 1040℃
The sample was heated and maintained at 170° C. to perform a 170-diffusion treatment. The treated product 2 thus treated was rapidly cooled and hardness H7) was measured to measure the hardening depth. Based on the results, we observed the carbon diffusion situation. The effective hardening depth was defined as Hv550 or more.

FIG. 14 is a diagram showing the effective hardening depth after carburizing. The length of the vertical line indicates the range of variation. As is clear from the figure, in the present invention, the error is 0.5B for the target effective hardening depth of 1.5B in 5-carburizing and 170-diffusion treatments.
It is around 1 m. On the other hand, with the conventional method, if a carburized layer is not formed, or even if it is formed, a carburized layer with a surface carbon concentration above a certain value indicating the effective hardening depth is not formed, or if the carburized layer is not formed with a surface carbon concentration of 1 or 5 which is the target value. A carburized layer may be formed, and the range of variation tends to be very wide. However, with the method of the present invention, a nearly uniform carburized layer can be obtained over the entire product being treated, whereas with the conventional method, there is a lot of unevenness between the products being treated, making it difficult to obtain a stable and uniform carburized layer. I found out something.

When the processing time is constant, the factors that affect the above-mentioned variations in the depth of thermal hardening include the processing temperature and the carbon concentration on the surface of the workpiece. Although it is possible to maintain the processing temperature almost uniformly, the surface carbon concentration is affected by the position of the product to be processed, or the auxiliary electrode and the processed material, since the introduced CH4 gas is distributed throughout the furnace body. Since the amount of CH4 gas supplied between the products is smaller than the amount of consumption that diffuses inside, the actual amount of CH4 gas inside the product can be reduced regardless of location.
If the partial pressure of the four gases is low, the effective curing depth will vary. In contrast, according to the method of the present invention, the processing gas is uniformly supplied to the discharge region at high density and with little variation in gas partial pressure, so the gas partial pressure and gas density at the surface of the workpiece are improved. Processing can be performed uniformly and with little variation over the entire product to be processed.

〔Effect of the invention〕

In the conventional method, gaseous substances that contribute to the reaction are diffused throughout the reduced pressure container, and the treatment is performed by glow discharge on the surface of the processed object while causing fluctuations in the partial pressure of the processing gas. Since the gaseous substances that contribute to the reaction are uniformly distributed and supplied to the space between the auxiliary electrode and the auxiliary electrode, the gaseous substances are immediately reacted in the high ionization density 40-discharge chamber, and can be uniformly and efficiently applied to the object to be processed. In addition, it is possible to perform surface treatment such that unreacted gas is less likely to diffuse into the container, and it is possible to prevent unreacted gas from adhering to the container wall. The present invention can be effectively used for surface treatment in which one or more surface treatment layers, such as a surface diffusion layer or a surface coating layer, are formed on the whole or part of the surface of an article to be treated, and particularly for surface treatment in a high temperature range. Effective.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an example of a surface treatment apparatus used to carry out the present invention, FIG. 2 is an explanatory diagram showing an example of an apparatus used in the conventional ion nitriding process, and FIG. 3 is an explanatory diagram showing an example of the apparatus used in the conventional ion nitriding process.
FIG. 4 is an explanatory diagram showing an example of a conventional conductive member processing device; FIGS. 5, 6, and 7 are illustrations of the electrode structure and gas used in the method of the present invention. Perspective views showing three examples of supply means, Figure 8 is a diagram showing the gas distribution range when the size and interval of the gas jet ports are uniform, and Figure 9 is a diagram showing the gas amount and coating in the case of Figure 8. Figure 10 shows the thickness, and Figure 11 shows the preferred gas distribution range.
The figure shows the gas amount and film thickness in the case of Fig. 10, and Fig. 12 (a) t<b> shows the gas supply pipe with the gap between the gas jet ports changed, and the gas amount and film thickness in that case. Figures 13(a)-(b) are diagrams showing the gas supply pipes with different gas outlet sizes, and the gas amounts and coating thicknesses in those cases. Figure 14 is the diagram showing the carburizing process. It is a figure showing effective hardening depth. 1...Furnace body 2...Workpiece 4...
DC power supply 5m, 5b...Auxiliary electrode 6...
- Vacuum exhaust system 7...Anode terminal 8...Rotating cathode terminal 11...Vacuum measuring probe 12m, 12. b・
...Carrier and reaction gas 13...Gas flow control system 15...Metal halide storage container 16...Gas rotation supply mechanism 17...Gas supply pipe 2
1...Electric motor 22...Gas outlet Fig. 3 Fig. 8 Fig. 9 and above Gas lees pipe's first rising summer Cage No. 14 Fig. Law law

Claims (1)

[Claims] 1. An article to be treated is set as a cathode in a reduced pressure container, an auxiliary electrode connected to the cathode is arranged opposite to and near the article to be treated, and a gas substance is supplied into the container. In an ion surface treatment method in which a treated layer is formed on the surface of a workpiece under glow discharge with high ionization density, a gas supply pipe having a gas outlet located in a space between the workpiece and an auxiliary electrode is covered. An ion surface treatment method characterized by supplying a gaseous substance into the space from a gas outlet of a gas supply pipe while moving it relative to the treated product and the auxiliary electrode. 2. The ion surface treatment method according to claim 1, wherein the gas supply pipe has a plurality of gas jet ports, the diameter of which increases as it approaches the tip. 3. The ion surface treatment method according to claim 1, wherein the gas supply pipe has a plurality of gas jet ports whose intervals are narrower toward the tip.