KR20000060942A - Device for the Inner Surface Treatment of a Cylinder by Dynamic Plasma Diffusion - Google Patents

Abstract

PURPOSE: A device of treating the surface of an inner wall of pipe by the diffusion of a dynamic plasma is provided to treat uniformly the surface of an inner wall of a cylinder shaped pipe and to control the degree of surface treatment by using the dynamic characteristic of a plasma. CONSTITUTION: A device of treating the surface of an inner wall of pipe by the diffusion of a dynamic plasma comprises : a central electrode(c) of the same axle ; a current introduction electrode(a) to form a circular plate shaped tip ; a circular plate shaped pipe(s) to be contacted with a circular plate shaped current introduction electrode(a) and to form a vacuum tool and a part of an electrode ; an electrode for revolving current(b) to be contacted with one side of a circular plate shaped pipe(s) and to be connected with a central electrode(c).

Description

Device for the Inner Surface Treatment of a Cylinder by Dynamic Plasma Diffusion}

The present invention relates to a surface treatment apparatus of a cylindrical inner wall, and more particularly, a thin film using plasma to the inner wall of a cylindrical tube such as a barrel, barrel, and a launch tube in a cylindrical pipe or a military equipment for a mechanical element or a launcher of a nuclear power system and a general industry. The degree of surface treatment can be adjusted during surface treatment such as molding, and it is possible to perform homogeneous surface treatment and high speed thin film molding in cylindrical tube with longer length than inner diameter. Inner wall surface treatment by the diffusion of dynamic plasma which enables high quality surface treatment to be realized with excellent processability and productivity by allowing simultaneous adjustment of the diffusion rate, phase change and compound layer composition of the surface layer. Relates to a device.

In general, in the case of a neutral gas, plasma, which is in an ionized gas state, is influenced by a long ranged coluomb force even in distant particles, unlike a neutral gas, which is influenced by each other. (collective behavior), the positive and negative charge is balanced to about the same density, the overall quasi-neutral properties. Since plasma arc discharge was first attempted, such plasma has been widely used in applications such as light sources and display devices, fabrication of ultra-high integration electronic devices, synthesis of new materials, and production of functional thin films.

On the other hand, there is an apparatus for surface treatment of the inner wall of the cylindrical tube using a glow discharge plasma as shown in FIG. .

The apparatus for treating the surface of the inner wall of the cylindrical tube is arranged concentrically the tube (s) and the center electrode (c) in the vacuum vessel (v) and apply direct current or high frequency power to the tube (s) and the center electrode (c). Although PECVD or sputtering is used, the longer the length of the tube, the more difficult the uniform discharge is, and the lower the pressure, the lower the surface treatment rate is not satisfactory.

In order to overcome this disadvantage, an apparatus for surface treatment of inner walls by injecting plasma into a cylindrical tube (s) to be surface treated with a coaxial plasma gun (g) as shown in FIG. 2 has been developed. It is useful to apply to non-conducting tubes with very small apertures, but at the exit velocity of the coaxial plasma gun g, the plasma incident in the tube s is attenuated as it travels along the longitudinal axis of the tube s. The degree of surface treatment at the end and the end is different, but the longer the length of the tube (s), the more severe the deviation, moreover, if the material of the tube is difficult to apply. In addition, since the plasma generating unit and the surface treatment area are separated and they are housed in a separate vacuum vessel (V), the structure is complicated and the productivity is lowered.

An object of the present invention for solving the above problems is useful for obtaining a homogeneous surface treatment effect in a cylindrical tube with a length longer than the inner diameter, and adjusting the degree of surface treatment in the longitudinal direction is also applied to the strength of the magnetic field from the outside It is possible by modulating the discharge pulse power together with the / direction / spatial distribution, and the desired surface by controlling the rotational speed of the plasma by the intensity of the magnetic field external to the special structure such as the inner wall of the tube having the spiral structure like the barrel wire. It can be treated and the desired surface treatment to complex elements such as nitriding, carbonization, aC or T _i N, T _i AlN, T _i C, magnetite (Fe ₃ O ₄ ), Ni-W, Ni-B, CrN Depending on the layer, it is possible to select a suitable material for the working gas or the center electrode, and to achieve a high surface treatment speed due to the high density of the dynamic plasma, and the surface mouth to act for a very short time Surface layer heating without deformation of the base material by controlling the energy density allows the diffusion rate, phase shifts such as phases, and compound layer composition to be simultaneously processed to ensure good surface treatment with excellent processability and productivity. An inner wall surface treatment apparatus by diffusion of a dynamic plasma is provided.

1 is a cross-sectional view showing a schematic structure of an apparatus for surface treatment of a cylindrical tube inner wall using a conventional glow discharge plasma.

2 is a cross-sectional view showing a schematic structure of an apparatus for surface treatment of an inner wall by injecting plasma into a cylindrical tube to be surface treated with a conventional coaxial plasma gun.

3 is a cross-sectional view showing a schematic structure of an apparatus used when surface treatment of an inner wall of a conductive cylindrical metal tube using diffusion of dynamic plasma according to an embodiment of the present invention.

4 is a cross-sectional view showing a schematic structure of an apparatus used when surface treatment of an inner wall of a non-conductive cylindrical tube using diffusion of dynamic plasma according to another embodiment of the present invention.

FIG. 5 is a cross-sectional view illustrating a schematic structure of a device in which the device of FIG. 3 is modified to reciprocate a dynamic plasma layer in both directions. FIG.

6 is an output timing diagram of the DC pulse modulation power supply of FIG. 5;

<Description of the code | symbol about the principal part of drawing>

a: current introduction electrode b: current return electrode

c: center electrode d: insulator

e: working gas injection nozzle g: coaxial plasma gun

m: cylindrical mesh electrode p: plasma

s: cylindrical tube for surface treatment

V: vacuum vessel u1, u2: plasma position probe

D: inner diameter of cylindrical tube to be surface treated

L: length of cylindrical tube to be surface treated

i: discharge current v: plasma disk moving speed

B _s : magnetic field caused by discharge current B _e : axial magnetic field caused by external electromagnet

According to the present invention for achieving the above object, "inner wall surface treatment apparatus of cylindrical tube (s) by diffusion of dynamic plasma" is a coaxial center electrode (c) for plasma generation, around the center electrode (c) An end portion is formed in a disk shape and the current introduction electrode (a) having a cylindrical shape that continues to the disk shape, and a cylindrical tube (s) formed as part of the vacuum vessel and the electrode by one side in close contact with the cylindrical shape of the current introduction electrode (a) ) And a current return electrode (b) integrally in contact with the other side of the cylindrical tube (s) and insulated and connected to the coaxial central electrode (c) in the cylindrical tube (s).

In addition, a coaxial center electrode (c), a first current induction electrode (a) having a cylindrical shape with a distal end formed in a disc shape around the center electrode (c) and continuing in the disc shape, and one side of the current induction electrode The cylindrical tube s formed as part of the vacuum container and the electrode in hermetically contacting the cylindrical shape of (a) and the second current introduction electrode a in hermetically contacting the other side of the cylindrical tube s are integrally formed. And surface treating the inner wall of the cylindrical tube s while bidirectionally reciprocating the dynamic plasma layer p generated by selectively switching the electric fields of the first and second current introduction electrodes a. The tube is to be used as a vacuum container / electrode, and the device is simplified by not using a separate vacuum container, and even if the tube to be treated is a conductor such as a steel pipe in addition to an insulator such as glass or plastic. It is excellent in performance, and by integrating the plasma generating unit and the plasma surface treatment unit without separation, the device and the process are simple and realize the continuous high density plasma energy supply to increase the surface treatment speed and accuracy. Depending on the type, the material of the center electrode can be selected, and the pulse power can be modulated together with the strength / direction / distribution of the axial external magnetic field to be applied to the specific inner wall structure, and the degree of surface treatment in the longitudinal direction can be adjusted.

The above objects and various advantages of the present invention will become more apparent from the preferred embodiments of the invention described below with reference to the accompanying drawings by those skilled in the art.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is a cross-sectional view illustrating a schematic structure of an apparatus used when surface treating an inner wall of a conductive cylindrical metal tube using diffusion of dynamic plasma according to an embodiment of the present invention.

As shown in the figure, the cylindrical center electrode c and the cylindrical tube s for surface treatment are arranged concentrically. One end (left end) of this cylindrical structure is also positioned concentrically with the insulating layer d between the disc and the cylindrical introduction electrode a. The central electrode c of this part has a nozzle e for injecting the working gas. This nozzle (e) may be located in the disk structure of the introduction electrode (a) in some cases.

In addition, a window for irradiating a trigger electrode or a laser beam for inducing a discharge is provided here. Since the current flowing through the introduction electrode (a) contributes to the acceleration of the initial plasma, according to the embodiment, the degree of contribution may be reduced by the deformation of the electrode structure. The other end (right end) of the cylindrical structure is finished with a current return disk electrode (b), and the current return disk electrode (b) is insulated with the center electrode (c) and the insulator (d). The insulating layer such as the insulator (d) may be located between the disc electrode (b) for current return and the cylindrical tube (s) to be subjected to the inner wall surface treatment or the disc electrode (b) itself. The structure of the insulating layer is made of a structure and a material that does not cause breakdown or leakage even after several discharges.

The joint portion between the introduction electrode (a) and the cylindrical tube (s) for current surface treatment and the original electrode (b) for current return is electrically sealed while being vacuum sealed. In order to achieve both vacuum sealing and electrical continuity, a suitable method is used according to a specific cylindrical tube. For example, a gasket made of copper is satisfied in most cases. In the radially outer periphery of the cylindrical structure consisting of the introduction electrode (a), the cylindrical tube (s) and the current return disk electrode (b), a solenoid type magnet (Magnet) is installed concentrically to form an axial magnetic field (B _e ) It is provided in the tube (s).

Since the inside of the cylindrical tube (s) to be treated with the inner wall surface must be maintained in vacuum, the overall structure or assembly of the device is configured in a vacuum sealing method suitable for a specific cylindrical tube.

4 is a cross-sectional view illustrating a schematic structure of an apparatus used when surface treating an inner wall of a non-conductive cylindrical tube using diffusion of dynamic plasma according to another embodiment of the present invention.

In the figure, when the cylindrical tube (s) to be subjected to the inner wall surface treatment is an insulator such as plastic, a conductive cylindrical mesh (m) is inserted between the central electrode (c) and the cylindrical tube (s) to discharge electrode and plasma. Use as ion extraction electrode.

The above device includes a DC pulse modulation power supply, a high speed power transmission line, a magnet power supply, a piezo valve and an operating gas to generate plasma by a series of pulse discharges. The working gas injection system, which is composed of a working gas tank, and a vacuum pump are attached as shown in FIG. 4 as well as FIG. 3. Several exhaust ports are arranged radially at the center of the longitudinal axis of the original electrode for current return, and the exhaust ports are connected to a vacuum pump for evacuation. In the case of multi-element surface treatment, the working gas injection system is configured to supply several kinds of working gases at a certain fraction.

FIG. 5 is a cross-sectional view showing a schematic structure of a device in which the apparatus of FIG. 3 is modified to reciprocate the dynamic plasma layer p in both directions. FIG. It is also provided on the right end of the cylindrical structure, and each end is connected to each of the DC pulse modulation power supply (P1, P2) for generating a plasma by a series of pulse discharge. The vacuum exhaust and the operating gas injection are provided at both ends of the operating gas injection system and the vacuum exhaust system as in the case of Figure 3 or Figure 4 to have a corresponding role and function.

Next, the operation of the inner wall surface treatment apparatus by the diffusion of the dynamic plasma according to the present invention having the above-described configuration will be described in detail.

First, the operating gas is injected into the piezo valve (Valve) in a vacuum state and a high voltage pulse is applied to the pulse modulation power supply to start discharging from the left end of FIG. 3 or 4. At this time, the gas injection is synchronized with the high voltage pulse.

At the start of discharge, a trigger such as a trigger electrode or a laser can be used to assist. Depending on the process, the working gas can be discharged in a constant pressure state. When the discharge is started, the center electrode (c), the disk plasma layer (p), the inner surface of the cylindrical tube (s) to be treated, or in the case of Figure 4 consists of a cylindrical mesh (m), the current-carrying electrode (a) A discharge current (i) circuit is constructed such that a circumferential magnetic field B _s is generated between the central electrode c and the cylindrical structure.

This magnetic field causes the disk-shaped plasma layer p to be accelerated to perform the axial motion v. Circular plate at the same time as the external magnetic field (B _e) to be supplied from the electric magnet (Magnet) plasma layer (p) is rotated around the center electrode (c).

As a result, the plasma undergoes a helical motion inside the cylindrical tube s to be subjected to the inner wall surface treatment, and this dynamic plasma provides a uniform plasma diffusion distribution in the circumferential direction on the inner wall of the cylindrical tube s. In particular, by modulating and supplying current and energy to the plasma continuously during the movement of the dynamic plasma layer (p) in the axial direction, it is possible to provide a surface treatment having a uniform or uniform distribution in the axial direction on the inner wall of the cylindrical tube (s). . The disk-like plasma layer p surface-treats the entire inner wall while crossing the cylindrical tube s, and then disappears by reaching the current return electrode b. The series of discharges is repeated until the desired surface treatment results are obtained.

On the other hand, according to the specific cylindrical tube (s) to be subjected to the surface treatment and the required surface treatment layer, the outer diameter, material, length and type of working gas, gas injection amount and pulse shape of the injection gas, discharge voltage and current Device variables and process variables such as pulse shape, electrode polarity, plasma generation start position, intensity and direction of axial external magnetic field and space distribution, discharge cycle, frequency of discharge and series of discharge power modulation are adjusted. Likewise, in the case of surface treatment of the inner wall of the non-conductive cylindrical tube s, the material and the net size of the cylindrical net body m become important.

In addition, the apparatus of FIGS. 3 and 4 can be modified as shown in FIG. 5 as an example to increase the surface treatment speed, homogeneity and energy efficiency by reciprocating the dynamic plasma layer p in both directions. As shown in the output timing diagram of the DC pulse modulation power supply, this is done by alternately applying DC pulse power at both ends. Each DC pulse modulation power supply is operated with the feedback of the position signal of the dynamic plasma layer p measured by the electrostatic probe u1.u2 at each position when the dynamic plasma layer p reaches both ends. That is, when the dynamic plasma layer p reaches the left end, the signal output from the signal processor of u1 indicates the interruption of the output of P2 and the start of the output of P1. When the signal reaches the right end, the signal of u2 is reached. The signal output from the processor indicates the blocking of the P1 output and the start of the P2 output. The reciprocation of the series of dynamic plasma layers p is repeated until the desired surface treatment results are obtained.

As described above, in the present invention, the cylindrical tube to be surface treated also serves as a vacuum vessel and an electrode, and the center electrode has the same length as that of the cylindrical tube and is integrated without separating the plasma generating unit and the plasma surface treating unit. .

In this way, since a separate vacuum vessel is not used, the device and the process are simple and continuously supply energy to the high density plasma, so that even if the length / diameter ratio of the tube is large, the homogeneity of the surface treatment and the film forming speed are high. When adjusting the degree of surface treatment such as thin film thickness along the length direction, or when the inner wall of the tube is surface treated with a spiral inner structure such as a barrel wire, the strength and spatial distribution of the axial magnetic field applied from outside A series of discharge pulse power is modulated and surface treated.

The process desired surface to complex elements such as the structural nature of nitride, carbide of the device, aC, or T _i N, T _i AlN, T _i C, the magnetite _{(Fe 3 O 4), Ni} -W, Ni-B, CrN Depending on the type of layer, the appropriate type of operating gas and the center electrode are selected. Plasma acts only for a very short time on the surface to be treated and the energy and current density irradiated to the surface can be controlled, so if necessary, surface layer heating without deformation of the base material, such as diffusion rate, phase transition such as ?? phase, compound layer composition, etc. Adjustments are made simultaneously with thin film molding.

Thus, the present invention is a device for surface treatment of the inner walls of various cylindrical pipes and mechanical elements at high speed by using the dynamic plasma diffusion method, which can be put to practical use in the general industry and the military industry including nuclear power. .

As described above, according to the present invention, a device for surface treatment of various cylindrical mechanical elements by using the dynamic plasma diffusion method, which is useful for obtaining a homogeneous surface treatment effect in a cylindrical tube having a length longer than the inner diameter, It is also possible to adjust the degree of surface treatment along the longitudinal direction by modulating the discharge pulse power together with the intensity / spatial distribution of the magnetic field applied from the outside, and the specific structure such that the inner wall of the tube has a spiral structure such as the barrel wire. By controlling the rotational speed of the plasma by the intensity of the external magnetic field, the desired surface treatment can be achieved. Nitriding, carbonization, aC or T _i N, T _i AlN, T _i C, magnetite (Fe ₃ O ₄ ), Ni- According to the desired surface treatment layer ranging from composite elements such as W, Ni-B, CrN, etc., it is possible to select a suitable working gas or material of the center electrode. Fast surface treatment by high-density dynamic plasma and surface layer heating without deformation of base material by control of surface incident energy density acting for a very short time allows simultaneous adjustment of particle diffusion rate, phase change and compound layer composition Due to the fairness and productivity can be a good surface treatment, there is an effect that can be widely applied in the general industrial sector and the military industry.

Claims (3)

In the apparatus for injecting gas for plasma generation in a vacuum state and surface treatment of the inner wall of the cylindrical tube (s) based on the plasma diffusion based on the electric field and magnetic field, Coaxial center electrode (c) for the generation of plasma, a current-carrying electrode (a) having a cylindrical shape that is formed in a disc shape and has a disc shape around the center electrode (c), and one side of the current induction electrode ( The cylindrical tube (s) formed in part of the vacuum vessel and the electrode in hermetic contact with the cylindrical shape of a), and the coaxial central electrode (c) in the cylindrical tube (s) in hermetic contact with the other side of the cylindrical tube (s). And a current return electrode (b) which is insulated and connected to each other. According to claim 1, wherein when the cylindrical tube (s) is a non-conductive conductive connection between the current induction electrode (a) and the current return electrode (b), between the central electrode (c) and the cylindrical tube (s) An inner wall surface treatment apparatus for diffusing a dynamic plasma, further comprising a conductive cylindrical mesh (m) positioned at a portion thereof to serve as a discharge electrode and a plasma / ion extracting electrode. In the apparatus for injecting gas for plasma generation in a vacuum state and surface treatment of the inner wall of the cylindrical tube (s) based on the plasma diffusion based on the electric field and magnetic field, Coaxial center electrode (c), the first current-carrying electrode (a) having a cylindrical shape that is formed in a disk-shaped end portion around the center electrode (c) and continues to the disk shape, and one side of the current induction electrode (a) The cylindrical tube (s) formed as part of the vacuum container and the electrode in hermetic contact with the cylindrical shape of the diaphragm), and the second current induction electrode (a) in hermetic contact with the other side of the cylindrical tube (s). The dynamic plasma layer p generated by injecting gas for plasma generation in the vicinity of the first and second current induction electrodes a and selectively switching the electric fields of the first and second current induction electrodes a respectively. An inner wall surface treatment apparatus by diffusion of a dynamic plasma, characterized in that the inner wall of the cylindrical tube (s) is surface treated while reciprocating in both directions.