阅读说明：本技术 一种用于金属管内壁改性的装置及方法 (Device and method for modifying inner wall of metal pipe ) 是由 黄绍服 曾祥领 李君� 于 2021-07-01 设计创作，主要内容包括：本发明提出了一种用于小直径大深径比的金属管内壁改性的装置及方法,装置包括：反应腔室,待改性金属管设置在反应腔室中；反应腔室包括第一开口和第二开口,第一开口连通供气管路,第二开口连接真空泵；供气单元,用于向反应腔室内通入反应气流,供气单元通过供气管路与反应腔室连通；等离子体发生单元,位于供气单元与反应腔室之间,用于在供气管路内产生等离子体,等离子体随反应气流由供气管路进入反应腔室内；加热单元,用于对待改性金属管加热；电磁单元,产生电场和磁场,用于约束和控制进入反应腔室的等离子体束流,使等离子体在加热后的待改性金属管的内壁沉积。本发明的装置适用于低温、高长径比金属管内壁的改性。(The invention provides a device and a method for modifying the inner wall of a metal tube with small diameter and large depth-diameter ratio, wherein the device comprises the following steps: the reaction chamber is provided with a metal pipe to be modified; the reaction chamber comprises a first opening and a second opening, the first opening is communicated with the gas supply pipeline, and the second opening is connected with the vacuum pump; the gas supply unit is used for introducing reaction gas flow into the reaction chamber and is communicated with the reaction chamber through a gas supply pipeline; the plasma generating unit is positioned between the gas supply unit and the reaction chamber and used for generating plasma in the gas supply pipeline, and the plasma enters the reaction chamber along with reaction gas flow from the gas supply pipeline; the heating unit is used for heating the metal pipe to be modified; and the electromagnetic unit is used for generating an electric field and a magnetic field and is used for restraining and controlling the plasma beam current entering the reaction chamber so as to enable the plasma to be deposited on the inner wall of the heated metal tube to be modified. The device is suitable for modifying the inner wall of the metal pipe with low temperature and high length-diameter ratio.)

1. An apparatus for modifying the inner wall of a metal tube, comprising:

a reaction chamber in which a metal tube to be modified is disposed; the reaction chamber comprises a first opening and a second opening, the first opening is communicated with the gas supply pipeline, and the second opening is connected with the vacuum pump;

the gas supply unit is used for introducing reaction gas flow into the reaction chamber and is communicated with the reaction chamber through the gas supply pipeline;

the plasma generating unit is positioned between the gas supply unit and the reaction chamber and used for generating plasma in the gas supply pipeline, and the plasma enters the reaction chamber along with reaction gas flow from the gas supply pipeline;

the heating unit is used for heating the metal pipe to be modified;

and the electromagnetic unit is used for generating an electric field and a magnetic field and is used for restraining and controlling the plasma beam current entering the reaction chamber so as to deposit the plasma on the surface of the inner wall of the heated metal tube to be modified.

2. The apparatus as claimed in claim 1, wherein a pipe member is inserted into the reaction chamber, and the metal pipe to be modified is placed in the pipe member;

the first end of the pipe fitting extends out of the reaction chamber from the first opening to be connected with a gas supply pipeline, and the second end of the pipe fitting extends out of the reaction chamber from the second opening to be connected with the vacuum pump;

the gas supply unit is used for supplying reaction gas flow to the gas supply pipeline, and the plasma generated in the gas supply pipeline by the plasma generation unit enters the pipe fitting along with the reaction gas flow.

3. The apparatus as claimed in claim 2, wherein the tube is a quartz tube.

4. The apparatus as claimed in claim 1, wherein the gas supply unit is configured to supply at least three reactant gas flows into the gas supply pipeline;

preferably, the reaction gas flow input into the gas supply pipeline by the gas supply unit is nitrogen, hydrogen and argon.

5. The apparatus as claimed in claim 4, wherein the gas inlet end of the gas supply line is provided with a plurality of gas inlets, different reactant gas flows are supplied to the gas supply line through the respective gas inlets, and a flow meter is provided at each gas inlet for controlling the flow rate of the reactant gas flow supplied to the gas inlet.

6. The apparatus of claim 2, wherein the plasma generating unit comprises an inductive coil and a radio frequency generator, the inductive coil is electrically connected to the radio frequency transmitter, the inductive coil is disposed outside the gas supply pipeline and spaced from the gas supply pipeline, the radio frequency current emitted from the radio frequency transmitter generates plasma in the gas supply pipeline through the inductive coil, and the plasma enters the pipe member along with the reaction gas flow.

7. The apparatus as claimed in claim 2, wherein the heating unit comprises a high frequency power source and a high frequency coil electrically connected to the high frequency power source, the high frequency coil being provided around the inner wall of the pipe member, and the metal pipe to be modified is placed in an area surrounded by the high frequency coil.

8. The apparatus as claimed in claim 7, wherein the electromagnetic unit comprises an electromagnetic coil, a first electrode and a second electrode, wherein

The electromagnetic coil ring is arranged on the outer wall of the pipe fitting, and the high-frequency coil is positioned in an area surrounded by the electromagnetic coil;

the first electrode and the second electrode are positioned in the reaction chamber and are oppositely arranged on two sides of the pipe wall of the pipe fitting, and the first electrode and the second electrode are respectively arranged with the electromagnetic coil in a clearance mode.

9. The apparatus as claimed in claim 8, further comprising a base, wherein the plasma generating unit and the reaction chamber are disposed on the base;

the base is further provided with a movable guide rail, the reaction chamber is arranged on the guide rail, and the guide rail moves to drive the reaction chamber to move towards the direction close to or far away from the plasma generating unit within the length range of the pipe fitting.

10. A method for modifying an inner wall of a metal pipe, which comprises the step of using the apparatus for modifying an inner wall of a metal pipe according to claim 9, comprising:

placing a metal tube to be modified in a reaction chamber;

respectively starting the gas supply unit, the vacuum pump, the plasma generation unit and the heating unit;

controlling the reaction chamber to move at a certain speed in a direction away from the plasma generating unit;

and when the set modification time is reached, finishing the modification.

Technical Field

The invention belongs to the field of material surface modification, and particularly relates to a device and a method for modifying the inner wall of a metal pipe.

Background

The metal pipe fitting with small diameter and large depth-diameter ratio has wide application in various fields, for example, the metal pipe fitting is a candidate of an advanced nuclear reactor structural material in the nuclear power field, such as a cladding pipe of a sodium-cooled reactor fuel cladding system, a tritium-involved and helium-involved pipeline in a fusion reactor device, and the like, and in the national defense field, a body pipe of a tank, a cannon and a firearm, an engine pipeline, a radar waveguide pipe, a bearing and a piston sleeve of a armed war chariot, and the like; in biomedical applications, many artificial organs have a tubular shape, such as slender tubes, which are the most basic components for the preparation of artificial blood vessels. In practical applications, the inner surface of metal pipe often suffers severe damage due to corrosion, high temperature oxidation and diffusion, and frictional wear, resulting in a large economic loss. Therefore, it is very important to properly treat the inner surface of the metal pipe to make the metal pipe have higher hardness, better frictional wear resistance, high temperature resistance, high pressure resistance, corrosion resistance and the like.

At present, techniques for modifying the inner wall of the metal pipe include carburizing, nitriding, shot blasting, ion implantation, chemical vapor deposition, physical vapor deposition, and the like. The modification treatment of the inner wall of the metal tube with small diameter and large depth-diameter ratio has more challenges than the modification treatment of the outer surface of the metal tube, and the modification treatment of the inner wall of the metal tube mainly has the following technical problems: one is the size limitation, and some processes are difficult to implement, especially for elongated metal tubes. Secondly, the size is limited, the treatment medium is difficult to enter the metal tube, and even if the treatment medium enters the metal tube, the uniformity of the modified layer is difficult to ensure, thirdly, the reaction temperature is too high, and the deformation of the metal tube is inevitably influenced.

The Plasma Enhanced Chemical Vapor Deposition (PECVD) solves the technical problem of modification treatment of the inner wall of the tube to a certain extent, so that the modification quality is greatly improved. When the inner diameter of the tube becomes smaller or the length becomes larger, the reaction temperature becomes too high, which inevitably affects the metal pipe. Therefore, the need to find equipment suitable for the deposition of the inner wall of the metal tube with low temperature and high length-diameter ratio is a problem to be solved urgently.

The present invention has been made in view of this situation.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a device and a method for modifying the inner wall of a metal pipe with low temperature and high length-diameter ratio.

In order to solve the above technical problem, the present invention provides a device for modifying the inner wall of a metal tube, comprising:

a reaction chamber in which a metal tube to be modified is disposed; the reaction chamber comprises a first opening and a second opening, the first opening is communicated with the gas supply pipeline, and the second opening is connected with the vacuum pump;

the gas supply unit is used for introducing reaction gas flow into the reaction chamber and is communicated with the reaction chamber through the gas supply pipeline;

the plasma generating unit is positioned between the gas supply unit and the reaction chamber and used for generating plasma in the gas supply pipeline, and the plasma enters the reaction chamber along with reaction gas flow from the gas supply pipeline;

the heating unit is used for heating the metal pipe to be modified;

and the electromagnetic unit is used for generating an electric field and a magnetic field and is used for restraining and controlling the plasma beam current entering the reaction chamber so as to enable the plasma to be deposited on the inner wall of the heated metal tube to be modified.

Further optionally, a pipe fitting is inserted into the reaction chamber, and the metal pipe to be modified is placed in the pipe fitting;

the first end of the pipe fitting extends out of the reaction chamber from the first opening to be connected with a gas supply pipeline, and the second end of the pipe fitting extends out of the reaction chamber from the second opening to be connected with the vacuum pump;

the gas supply unit is used for supplying reaction gas flow to the gas supply pipeline, and the plasma generated in the gas supply pipeline by the plasma generation unit enters the pipe fitting along with the reaction gas flow.

Further optionally, the tube is a quartz tube.

Further optionally, the gas supply unit is configured to input at least three reactant gas flows into the gas supply line;

preferably, the reaction gas flow input into the gas supply pipeline by the gas supply unit is nitrogen, hydrogen and argon.

Further optionally, the gas inlet end of the gas supply pipeline is provided with a plurality of gas inlets, different reaction gas flows are input into the gas supply pipeline through the separate gas inlets, each gas inlet is provided with a flow meter, and the flow meter is used for controlling the flow rate of the reaction gas flow input by the corresponding gas inlet.

Further optionally, the plasma generating unit includes inductance coil and radio frequency generator, inductance coil with the radio frequency emitter electricity is connected, inductance coil cover is established the outside of air supply line and with air supply line clearance sets up, the radio frequency electric current of radio frequency emitter transmission passes through inductance coil is in produce plasma in the air supply line, plasma enters along with the reaction air current in the pipe fitting.

Further alternatively, the heating unit may include a high-frequency power source and a high-frequency coil electrically connected to the high-frequency power source, the high-frequency coil being provided around an inner wall of the pipe member, and the metal pipe to be modified being placed in an area surrounded by the high-frequency coil.

Further optionally, the electromagnetic unit comprises an electromagnetic coil, a first electrode and a second electrode, wherein

The electromagnetic coil ring is arranged on the outer wall of the pipe fitting, and the high-frequency coil is positioned in an area surrounded by the electromagnetic coil;

the first electrode and the second electrode are positioned in the reaction chamber and are oppositely arranged on two sides of the pipe wall of the pipe fitting, and the first electrode and the second electrode are respectively arranged with the electromagnetic coil in a clearance mode.

Further optionally, the plasma processing apparatus further comprises a base, wherein the plasma generation unit and the reaction chamber are arranged on the base;

the base is further provided with a movable guide rail, the reaction chamber is arranged on the guide rail, and the guide rail moves to drive the reaction chamber to move towards the direction close to or far away from the plasma generating unit within the length range of the pipe fitting.

The second objective of the present invention also provides a method for modifying the inner wall of a metal pipe, which uses the above device for modifying the inner wall of a metal pipe, and comprises:

placing a metal tube to be modified in a reaction chamber;

respectively starting the gas supply unit, the vacuum pump, the plasma generation unit and the heating unit;

controlling the reaction chamber to move at a certain speed in a direction away from the plasma generating unit;

and when the set modification time is reached, finishing the modification.

After adopting the technical scheme, compared with the prior art, the invention has the following beneficial effects:

the device and the method for modifying the inner wall of the metal pipe fitting utilize the electric field and the magnetic field generated by the electromagnetic unit to restrain and control the plasma beam, can effectively reduce the influence of the film preparation temperature on the metal pipe, realize the uniform deposition of the plasma on the inner wall of the heated metal pipe, and are particularly suitable for modifying the inner wall of the metal pipe with low temperature and high length-diameter ratio.

The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention, are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention without limiting the invention to the right. It is obvious that the drawings in the following description are only some embodiments, and that for a person skilled in the art, other drawings can be derived from them without inventive effort. In the drawings:

FIG. 1: the device for modifying the inner wall of the metal tube is disclosed by the embodiment of the invention.

Wherein: 1-a plasma generating unit; 2-a reaction chamber; 3-a heating unit; 4-a vacuum pump; 5-a gas supply line; 7-a metal tube to be modified; 8-a scaffold; 9-a pipe fitting; 10-a flange connector; 11-an inductor coil; 31-a high-frequency coil; 41-vacuum gauge; 51-an air inlet; 52-a flow meter; 61-an electromagnetic coil; 62-a first electrode; 63-a second electrode; 100-a base; 110-guide rail.

It should be noted that the drawings and the description are not intended to limit the scope of the inventive concept in any way, but to illustrate it by a person skilled in the art with reference to specific embodiments.

Detailed Description

In the description of the present invention, it should be noted that the terms "inside", "outside", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, which are only for convenience in describing the present invention and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and operate, and thus, should not be construed as limiting the present invention.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," "contacting," and "communicating" are to be construed broadly, e.g., as meaning fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; may be directly connected or indirectly connected through an intermediate. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

The present embodiment proposes an apparatus for modifying the inner wall of a metal tube, as shown in fig. 1, comprising: a reaction chamber 2, a gas supply unit, a plasma generation unit 1, a heating unit 3, and an electromagnetic unit. The metal pipe 7 to be modified is arranged in the reaction chamber 2; as shown in fig. 1, a support 8 is disposed in the sensing chamber, the metal tube 7 to be modified is disposed on the support 8, and a plurality of metal tubes can be disposed on the support 8, and the reaction chamber 2 of this embodiment can modify the inner walls of the plurality of metal tubes at the same time. The reaction chamber 2 comprises a first opening and a second opening, the first opening is communicated with the gas supply pipeline 5, and the second opening is connected with the vacuum pump 4; the gas supply unit is used for introducing reaction gas flow into the reaction chamber 2 and is communicated with the reaction chamber 2 through a gas supply pipeline 5; the plasma generating unit 1 is positioned between the gas supply unit and the reaction chamber 2 and is used for generating plasma in the gas supply pipeline 5, and the plasma enters the reaction chamber 2 along with the reaction gas flow through the gas supply pipeline 5; the heating unit 3 is used for heating the metal pipe 7 to be modified; the electromagnetic unit generates an electric field and a magnetic field for restraining and controlling the plasma beam current entering the reaction chamber 2, so that the plasma is deposited on the inner wall of the heated metal tube 7 to be modified.

The inner wall modification device for the metal pipe fitting 9 utilizes the electric field and the magnetic field generated by the electromagnetic unit to restrain and control the plasma beam flow, realizes the uniform deposition of the plasma on the inner wall of the heated metal pipe, and is particularly suitable for modifying the inner wall of the metal pipe with low temperature and high length-diameter ratio.

Further optionally, a pipe fitting 9 is inserted into the reaction chamber 2, the metal pipe 7 to be modified is placed in the pipe fitting 9, the pipe fitting 9 is optionally a quartz pipe fitting 9 made of high-purity quartz, a vacuum atmosphere chamber is formed in the pipe fitting 9 through a vacuum pump 4, the length of the quartz pipe is 300mm-500mm, and the pipe diameter of the quartz pipe fitting 9 is 1.5 inches-2 inches; a first end of the pipe 9 extends out of the reaction chamber 2 from the first opening to be connected with the gas supply pipeline 5, and optionally, the first end of the pipe 9 is connected with a gas outlet end of the gas supply pipeline 5 through a flange connector 10. The flange connector 10 is arranged to facilitate the installation and the disassembly of the workpiece, and simultaneously, the plasma in the gas supply pipeline 5 can directly enter the metal pipe.

The second end of the pipe 9 extends out of the reaction chamber 2 from the second opening and is connected with the vacuum pump 4; the vacuum pump 4 vacuumizes the pipe fitting 9 to form a vacuum atmosphere chamber; alternatively, the pumping speed of the vacuum pump 4 is 1L/s-2L/s, and the ultimate vacuum is 1X 10^-1Pa. A vacuum gauge 41 is further provided at the second end of the pipe member 9 for measuring the degree of vacuum in the pipe member 9, the measuring range of the vacuum gauge 41 being 1 x 10^-2Pa～1×10⁵Pa, the computer can collect the vacuum value in real time. The reaction gas flow provided by the gas supply unit enters the gas supply pipeline 5, and the plasma generated in the gas supply pipeline 5 by the plasma generation unit 1 enters the pipe 9 along with the reaction gas flow. Optionally, the pipe wall of the first end of the pipe 9 is spaced from the first opening, and the pipe wall of the second end of the pipe 9 is spaced from the second opening.

Further optionally, the gas supply unit inputs at least three reaction gas flows into the gas supply line 5; and the reaction gas flow is a high-purity gas source. As shown in fig. 1, the gas supply unit supplies A, B, C three kinds of high purity gas sources, which are mixed and then introduced into the gas supply line 5, and plasma is generated by the plasma generation unit. Preferably, the reaction gas flows input into the gas supply line 5 by the gas supply unit are nitrogen, hydrogen and argon.

Further alternatively, the gas inlet end of the gas supply line 5 is provided with a plurality of gas inlets 51, different reactant gas flows are input into the gas supply line 5 through the individual gas inlets 51, each gas inlet 51 is provided with a flow meter 52, and the flow meter 52 is used for controlling the flow rate of the reactant gas flow input corresponding to the gas inlet 51. Controlling the air inlet flow rate within a set flow rate range can enable the plasma to be uniformly deposited on the inner wall surface of the metal tube, and the excessive or insufficient air inlet flow rate can cause uneven thickness of a deposited film or prevent the deposited film from being deposited in the metal tube.

The mass flow meter 52 of the MFC is selected as the flow meter 52, the measuring range is 10 sccm-1000 sccm, the control precision is +/-1.0 percent F.S, and the response time is 1s, and can be controlled by a computer.

Further optionally, the plasma generating unit 1 includes an inductance coil 11 and a radio frequency generator, the inductance coil 11 is electrically connected to the radio frequency transmitter, the inductance coil 11 is sleeved outside the air supply pipeline 5 and is arranged in a gap with the air supply pipeline 5, the radio frequency current transmitted by the radio frequency transmitter generates plasma in the air supply pipeline through the inductance coil 11, and the plasma enters the pipe 9 along with the reaction air flow.

Specifically, as shown in fig. 1, the plasma generation unit 1 is located outside the gas supply pipeline 5, the gas supply pipeline 5 is a vacuum pipeline, and the gas supply pipeline 5 is made of a quartz tube. The plasma generating unit 1 comprises an inductance coil 11, a power-adjustable radio frequency generator and an impedance matching circuit thereof, wherein the inductance coil 11 is sleeved outside the air supply pipeline 5 and is arranged in a clearance with the air supply pipeline 5, namely the inner diameter of the inductance coil 11 is processed according to the outer diameter of the air supply pipeline 5, so that the inductance coil can be compactly sleeved outside the air supply pipeline 5 and is just not contacted with the outer wall of the air supply pipeline 5, and therefore, on one hand, the radio frequency power can be concentrated on the reaction gas near the inner bottom of the air supply pipeline 5 so as to generate high-density plasma; on the other hand, the inductance coil 11 is just not contacted with the outer wall of the air supply pipeline 5, so that local overheating of the air supply pipeline 5 is avoided. The optimum spacing between the inductor winding 11 and the air supply line 5 is in the range 1mm-2 mm. The gas supply unit inputs at least three kinds of reaction gas flows into the gas supply pipeline 5, the reaction gases enter the gas supply pipeline 5 after being mixed, an inductance coil 11 in the plasma generation unit is communicated with the radio frequency generator, the mixed gas in the gas supply pipeline 5 generates plasma, the mixed gas with the plasma enters the reaction chamber 2 from the gas supply pipeline 5, and the plasma is deposited on the inner wall of a metal pipe fitting arranged in the reaction chamber 2.

Further alternatively, the heating unit 3 comprises a high-frequency power supply and a high-frequency coil 31 electrically connected to the high-frequency power supply, the high-frequency coil 31 being disposed around the inner wall of the pipe member 9, optionally against the inner wall of the pipe body, and the metal pipe 7 to be modified being placed in the area surrounded by the high-frequency coil 31.

Specifically, the heating unit 3 is a high-frequency heater, and includes a high-frequency power supply and a transformer thereof, a high-frequency coil 31, and a cooling system. Induction heating is induced by the induced current (eddy current loss) generated by a conductor under the action of a high-frequency magnetic field and the action of a magnetic field in the conductor (hysteresis loss). When the metal conductor is in a high-frequency alternating electric field, induced electromotive force is generated in the metal conductor according to the Faraday's law of electromagnetic induction, and strong induced current is generated due to the small resistance of the conductor. According to Joule-Lenz law, the alternating magnetic field enables current in the conductor to flow towards the surface of the conductor to cause a skin effect, the density of the current is in direct proportion to the frequency, the higher the frequency is, the induced current density is concentrated on the surface of the conductor, namely the skin effect is more serious, the effective conducting area is reduced, the resistance is increased, and therefore the temperature of the conductor is rapidly increased. When a current flows through the conductor, a magnetic field is simultaneously generated around the conductor, and a high-frequency current flows to an induction coil 11 (usually made of copper tube) wound in a ring shape or other shapes. Thus, a strong magnetic beam whose polarity is instantaneously changed is generated in the coil, and the metal material to be heated is placed in the induction coil, so that the magnetic beam penetrates the entire material to be heated, a large eddy current is generated in the material to be heated in a direction opposite to the heating current, joule heat is generated by the resistance of the metal material to be heated, and the temperature of the metal material itself is rapidly increased, thereby completing the heating of the metal workpiece.

Further alternatively, the electromagnetic unit comprises an electromagnetic coil 61, a first electrode 62 and a second electrode 63, wherein the electromagnetic coil 61 is annularly arranged on the outer wall of the pipe member 9, and the high-frequency coil 31 is positioned in the area surrounded by the electromagnetic coil 61; the first electrode 62 and the second electrode 63 are located in the reaction chamber 2 and oppositely arranged on two sides of the pipe wall of the pipe 9, and the first electrode 62 and the second electrode 63 are respectively arranged with a gap from the electromagnetic coil 61.

The electromagnetic coil 61 generates a magnetic field and the first electrode 62 and the second electrode 63 generate an electric field, the gap between the first electrode 62, the second electrode 63 and the electromagnetic coil 61 being optionally 5 mm. The electromagnetic unit generates a magnetic field through the electromagnetic coil 61 to restrain and control the plasma beam current, and plasma is deposited on the inner wall of the tube. The first electrode 62 and the second electrode 63 are connected with a power supply, and the generated electric field restrains plasma.

Further optionally, the plasma processing device further comprises a base 100, wherein the plasma generating unit and the reaction chamber 2 are arranged on the base 100; the base 100 is further provided with a movable guide rail 110, the reaction chamber 2 is disposed on the guide rail 110, and the guide rail 110 moves to drive the reaction chamber 2 to move toward or away from the plasma generating unit 1 within the length range of the pipe 9. In the embodiment, the reaction chamber 2 moves at a certain speed in the process of modifying the inner wall of the metal pipe, so that the plasma is uniformly distributed on the inner wall of the metal pipe 9, the deposition quality and efficiency are improved, a uniform film is obtained, and the modification effect is improved. The guide rail 110 is self-locking, and is opened when the workpiece is mounted, so that the reaction chamber 2 is moved close to the plasma generation unit 1, and the reaction chamber 2 is fixed when the workpiece reaches a set position.

The embodiment further provides a method for modifying the inner wall of the metal pipe 9, which adopts the device for modifying the inner wall of the metal pipe 9, and the method comprises the following steps:

placing a metal tube 7 to be modified in the reaction chamber 2;

respectively starting the gas supply unit, the vacuum pump 4, the plasma generation unit 1 and the heating unit 3; controlling the vacuum degree in the tube body to be 150pa-200 pa;

controlling the reaction chamber 2 to move at a certain speed in a direction away from the plasma generating unit;

and when the set modification time is reached, finishing the modification.

Although the present invention has been described with reference to a preferred embodiment, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.