CN112676780A - Plasma electrochemical jet flow composite processing method and device - Google Patents
Plasma electrochemical jet flow composite processing method and device Download PDFInfo
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Abstract
The invention relates to the technical field of composite processing, and discloses a plasma electrochemical jet composite processing method and a plasma electrochemical jet composite processing device. The plasma electrochemical jet flow composite processing device comprises a frame, a working table, a clamp, a spraying device and a control device, wherein the frame is provided with the working table; the composite processing mode of electrolytic plasma processing and electrochemical jet processing can be realized only by clamping a workpiece to be processed on the fixture, connecting the nozzle to the negative electrode of the power supply, connecting the workpiece to the positive electrode of the power supply and spraying the electrolyte on the surface of the workpiece through the nozzle, and the composite processing mode has a simple structure and can effectively reduce the processing cost.
Description
Technical Field
The invention relates to the technical field of composite processing, in particular to a plasma electrochemical jet composite processing method and a plasma electrochemical jet composite processing device.
Background
With the continuous innovation of semiconductor technology, third generation semiconductor materials such as silicon carbide (SiC) have great potential in the aspect of manufacturing high-frequency, high-temperature and radiation-resistant high-power semiconductor devices due to the advantages of large forbidden band width, high breakdown electric field, high thermal conductivity and the like in recent years. The conventional processing methods mainly include wet etching, dry etching, electric spark, laser, chemical or electrochemical processing and the like. The chemical inert metal plays an important role in the high technical fields of aerospace, energy, medical treatment and the like due to the superior material properties of the chemical inert metal, for example, niobium (Nb) and alloy thereof can be applied to a superconducting magnet, high-temperature alloy can be applied to a rocket thruster nozzle, a gas turbine engine and a heat-resistant and burning-resistant device, and titanium (Ti) can be used for manufacturing medical instruments and is a good biocompatible material. However, chemically inert metals such as niobium and titanium, and semiconductor materials such as silicon and silicon carbide have high hardness, high brittleness and high chemical stability, and are difficult to process by conventional methods.
Specifically, the pattern cannot be precisely controlled by wet etching, and the etchant is a dangerous strong acid and strong base such as hydrofluoric acid or potassium hydroxide; the dry etching has the risk of wafer damage, and the equipment is complex and high in cost, so that the dry etching is not suitable for mass production; the electric spark and laser processing can generate a heat affected zone, a recast layer or microcracks on the surface of the material; electrochemical machining is not suitable for chemically inert materials, for example, materials such as niobium or silicon carbide and the like are combined with oxygen, an oxide film insulating layer is generated on the surface to prevent electrochemical reaction, and an acidic or alkaline electrolyte is usually adopted to remove the oxide film, so that the danger is high and the environment is not friendly, and the application of conventional electrochemical jet flow in chemically inert material machining is limited.
Disclosure of Invention
The present invention is directed to solving at least one of the problems of the prior art. Therefore, the invention provides a plasma electrochemical jet flow composite processing method which can realize the surface selective processing of a chemical inert material and provides a plasma electrochemical jet flow composite processing device.
According to a first aspect of the invention, a plasma electrochemical jet composite processing method includes: spraying electrolyte to a workpiece to be processed by a nozzle of a spraying device in an electrochemical jet mode through the spraying device, applying an electric field between the nozzle and the workpiece, and generating plasma on the surface of the workpiece to break down an oxide film generated by the electrochemical jet to remove the surface material of the workpiece under a set voltage.
The plasma electrochemical jet flow composite processing method provided by the embodiment of the invention has at least the following beneficial effects: the electrolyte forms jet flow through the jet device and is jetted on the workpiece, and plasma is generated on the surface of the workpiece by applying proper voltage, so that an oxide film generated on the surface of the workpiece due to electrochemical jet flow is broken down, the combination of electrolytic plasma processing and electrochemical jet flow processing is realized, and the processing of a chemical inert material is realized.
According to some embodiments of the invention, the electric field is applied between the nozzle and the workpiece by: the workpiece is connected to a positive power supply and the nozzle is connected to a negative power supply.
According to some embodiments of the present invention, the power supply is set to a constant voltage output mode, and the current waveform of the output of the power supply is a direct current waveform or a pulse waveform, and the voltage range is 100V to 300V.
According to some embodiments of the invention, the initial gap between the nozzle and the workpiece is 0.2mm to 0.8 mm.
According to some embodiments of the invention, the electrolyte is NaNO with a mass fraction ranging from 0.5% to 20%3The electrolyte is a neutral salt solution such as NaCl aqueous solution.
According to some embodiments of the invention, the trajectory of the nozzle relative to the surface of the workpiece is controlled to machine a desired position.
According to a second aspect of the invention, a plasma electrochemical jet composite processing apparatus includes:
the machining device comprises a rack, wherein a workbench is arranged on the rack, and a clamp for clamping a workpiece to be machined is arranged on the workbench;
the spraying device comprises a nozzle, the nozzle faces the clamp and is used for spraying electrolyte to the workpiece;
and the anode of the power supply device is connected with the workpiece, and the cathode of the power supply device is connected with the nozzle.
The plasma electrochemical jet flow composite processing device provided by the embodiment of the invention has at least the following beneficial effects: the composite processing mode of electrolytic plasma processing and electrochemical jet processing can be realized only by clamping a workpiece to be processed on the clamp, connecting the nozzle to the negative electrode of the power supply, connecting the workpiece to the negative electrode of the power supply and spraying the electrolyte on the surface of the workpiece through the nozzle. The plasma electrochemical jet flow combined machining device provided by the embodiment of the invention can be applied to the plasma electrochemical jet flow combined machining method provided by the embodiment, realizes a combined machining mode of electrolytic plasma machining and electrochemical jet flow machining, has a simple structure, and can effectively reduce the machining cost.
According to some embodiments of the present invention, the plasma electrochemical jet composite processing apparatus further comprises a driving device connected to the frame for driving the relative movement of the stage and the nozzle.
According to some embodiments of the invention, the work bench is further provided with an electrolytic bath, and the clamp is placed in the electrolytic bath, and the electrolytic bath is used for collecting and discharging the electrolyte sprayed from the nozzle.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
The invention is further described with reference to the following figures and examples, in which:
FIG. 1 is a schematic diagram of a plasma electrochemical jet hybrid processing method according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a plasma electrochemical jet hybrid processing method according to an embodiment of the present invention;
FIG. 3 is a schematic block diagram of a plasma electrochemical jet hybrid processing apparatus according to an embodiment of the present invention;
FIG. 4 is a schematic perspective view of a part of a plasma electrochemical jet hybrid processing apparatus according to an embodiment of the present invention;
FIG. 5 is a schematic illustration of the formation of an oxide film on a chemically inert semiconductor silicon carbide surface;
FIG. 6 is a schematic illustration of the material removal of FIG. 5;
FIG. 7 is a schematic view of the process of changing from the electrochemical anodization region to the plasma discharge region under different process parameters;
FIG. 8 is an example of a micro-groove pattern machined on a semiconductor silicon surface of a chemically inert material;
FIG. 9 shows an example of micro-groove pattern machined into the surface of niobium metal;
FIG. 10 is another example of a semiconductor silicon surface having a micro-trench pattern machined therein;
FIG. 11 shows another example of micro-groove pattern machined into the surface of niobium metal.
Reference numerals:
a nozzle 100, an electrolyte tank 110, a liquid sending pipeline 120, a liquid return pipeline 130, a liquid sending device 140, a filter 150 and a pressure gauge 160; workpiece 200, discharge 210, oxide film breakdown 220, oxide film 230, bubble 240; a power supply device 300, a power supply anode 310, a power supply cathode 320, an oscilloscope 330; an electrolyte 400; an initial gap 500; a worktable 600, a clamp 610, an electrolytic bath 620; a first driving part 710, a second driving part 720, a third driving part 730; curves L1, L2, L3, anodization region S1, and discharge region S2.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.
In the description of the present invention, it should be understood that the orientation or positional relationship referred to in the description of the orientation, such as the upper, lower, front, rear, left, right, etc., is based on the orientation or positional relationship shown in the drawings, and is only for convenience of description and simplification of description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.
If the first and second are described for the purpose of distinguishing technical features, they are not to be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated or implicitly indicating the precedence of the technical features indicated.
In the description of the present invention, unless otherwise explicitly limited, terms such as arrangement, installation, connection and the like should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above terms in the present invention in combination with the specific contents of the technical solutions.
In the description of the present invention, reference to the description of the terms "one embodiment," "some embodiments," "an illustrative embodiment," "an example," "a specific example," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The chemical inert metal plays an important role in the high technical fields of aerospace, energy, medical treatment and the like due to the superior material properties of the chemical inert metal, for example, niobium (Nb) and alloy thereof can be applied to a superconducting magnet, high-temperature alloy can be applied to a rocket thruster nozzle, a gas turbine engine and a heat-resistant and burning-resistant device, and titanium (Ti) can be used for manufacturing medical instruments and is a good biocompatible material. With the continuous innovation of semiconductor technology, third generation semiconductor materials such as silicon carbide (SiC) have great potential in the aspect of manufacturing high-frequency, high-temperature and radiation-resistant high-power semiconductor devices due to the advantages of large forbidden band width, high breakdown electric field, high thermal conductivity and the like in recent years. However, chemically inert metals such as niobium and titanium, and semiconductor materials such as silicon and silicon carbide have high hardness, high brittleness and high chemical stability, and are difficult to process by conventional methods.
In the semiconductor technology, etching is a technology for selectively etching or stripping a material substrate or a surface covering film according to the design requirements of a mask pattern, and is divided into wet etching and dry etching. Wherein: dry etching, which is to remove materials by physical bombardment and chemical action of plasma on the surface of the materials, can realize anisotropic etching, but has the risk of wafer damage due to ion bombardment, and has complex equipment and high cost, thus being not suitable for mass production. Compared with the dry etching, the wet etching has low cost, and because silicon carbide has excellent chemical stability, the silicon carbide can hardly be corroded by conventional acid or alkali solution, so an electric field or ultraviolet light is generally introduced to assist the wet etching, but the transverse etching rate of the wet etching is close to the longitudinal etching rate, so the silicon carbide is isotropically etched, the precision of pattern transfer of the wet etching is low, meanwhile, the etching rate of the silicon carbide wet etching is slower to tens of hundreds of nanometers per minute, and in addition, an etchant for the silicon carbide wet etching is generally high-concentration hydrofluoric acid or molten potassium hydroxide, which causes great harm to human bodies and environment.
Other machining methods such as electric spark, laser, chemical or electrochemical machining methods are widely used, and each has the advantages and disadvantages that: spark and laser machining use thermal energy to melt and evaporate material, but the surface of the material can generate heat affected zones, recast layers or microcracks. The electrochemical machining realizes the localized removal of the material by utilizing the electrochemical anode dissolution reaction of the workpiece material in the electrolyte, does not generate tool loss, has no heat affected zone and residual stress after the machining, and does not generate workpiece surface damage. During machining, the electrolyte is sprayed to the surface of a workpiece to be machined at a high speed, electrolytic punching, milling, cutting and other operations can be performed, and the method has the characteristics of simplicity, flexibility, controllable machining area and good machining flexibility. However, since the surface of an inert material such as niobium or silicon carbide is combined with oxygen to form an oxide film insulating layer to prevent the electrochemical reaction, the oxide film needs to be removed, and the oxide film is usually removed by using an acidic or alkaline electrolyte, which is highly dangerous and environmentally unfriendly, thereby limiting the application of the conventional electrochemical machining in the machining of chemically inert materials.
Compared with the conventional processing method, the plasma electrochemical jet flow composite processing method provided by the invention adopts a composite processing mode of electrolytic plasma processing and electrochemical jet flow processing. Electrolytic plasma technology, also known as plasma electrolytic oxidation, is a composite technology combining electrolysis and plasma discharge, and has been rapidly developed in recent years because it can significantly improve surface properties and realize a surface coating having high environmental compatibility. In the electrolytic plasma processing process, an electric field is applied between a tool electrode and a workpiece in an electrolyte environment, the strong ohmic heat action under the action of high voltage causes the electrolytic gas on the surface of the electrode to be separated out and the electrolyte solution to be evaporated, the surface of the electrode is discharged to generate plasma, a series of chemical, electrical and thermal reactions are generated, and further, the oxidation, coating, coloring, deposition and material removal such as surface polishing and cleaning treatment can be realized on the surface of a workpiece material. The embodiment of the invention adopts the combination of electrolytic plasma processing and electrochemical jet processing, the electrolyte forms jet flow through the jet device and is jetted on the workpiece, and plasma is generated on the surface of the workpiece by applying proper voltage, so that an oxidation film generated by the electrochemical jet flow on the surface of the workpiece is broken down, and the processing of a chemical inert material is realized.
FIG. 1 is a schematic diagram of a plasma electrochemical jet hybrid processing method according to an embodiment of the present invention, and FIG. 2 is a schematic diagram of a plasma electrochemical jet hybrid processing method according to an embodiment of the present invention, in which NO is shown3 -、Na+、H2O、H2Showing ions and molecules in the electrolyte, arrows in the drawings show the flow direction of the electrolyte, and referring to fig. 1 and 2, in the plasma electrochemical jet composite processing method of the embodiment, the electrolyte 400 is sprayed to a workpiece 200 to be processed by a nozzle 100 of a spraying device in an electrochemical jet manner through the spraying device, and an electric field is applied between the nozzle 100 and the workpiece 200, at this time, the electric field intensity acting on an oxide film 230 (shown by thick lines in the drawings) is very high, a discharge 210 is generated on the electrode surface of the workpiece 200 to generate plasma, and under a set voltage, plasma is generated on the surface of the workpiece 200The oxide film 230 produced by the electrochemical jet can be broken down, i.e., oxide film breakdown 220 can be achieved, to remove material from the workpiece 200 for selective processing of chemically inert materials.
Taking silicon carbide as an example, compared with the etching technology, the plasma electrochemical jet flow composite processing method provided by the invention has the advantages of high efficiency, low cost, environmental protection and no pollution; compared with laser and electric spark machining, the plasma electrochemical jet flow composite machining method provided by the invention does not generate a heat affected zone to reduce the surface quality, and does not have tool loss; taking niobium as an example, compared with an electrochemical jet processing method, the plasma electrochemical jet composite processing method provided by the invention can remove chemically inert materials by removing an oxidation film through combination of plasma discharge; compared with electrolytic plasma technology, the composite processing method provided by the invention has the characteristics of flexibility and convenience, and can realize selective material removal. Therefore, by compounding the electrochemical jet processing method and the electrolytic plasma technology, the embodiment of the invention plays respective advantages to realize the processing of the chemical inert material, avoids the restriction factors of complex process flow, multiple intermediate steps, easy environmental pollution, need of strict safety protection and the like of the traditional etching technology, reduces the cost and develops a new process method for related product preparation modes.
In the plasma electrochemical jet composite processing method of the above embodiment, the electric field is applied between the nozzle 100 and the workpiece 200 in such a manner that: the plasma electrochemical jet flow composite processing method of the embodiment is characterized in that an electric field is applied between the workpiece 200 to be processed at the anode and the cathode metal nozzle 100, an oxide film 230 is generated on the surface of the anode workpiece 200 in the processing area due to electrochemical redox reaction, meanwhile, oxygen bubbles 240 are generated to form a gas film by the contact interface of the oxide film 230 and the electrolyte 400 to generate gas, and when the applied voltage exceeds a critical value, plasma discharge is generated in the spraying area to destroy the oxide film 230 by destroying the oxide film 230 and the electrolyte film formed on the surface of the workpiece 200, so that the electrochemical erosion of the material at high temperature is realized. In this embodiment, the power supply is set to be in a constant voltage output mode, the voltage range is 100V to 300V, and the specific value can be reasonably configured according to the actual processing material and the processing requirement. In addition, the current waveform output by the power supply is a direct current waveform or a pulse waveform, and an oscilloscope probe can be used for detecting voltage and current signals during processing so as to monitor the current during processing.
In the plasma electrochemical jet flow compound processing method of the embodiment, the electrolyte 400 is a neutral salt solution, which avoids strong acid and strong alkali solutions such as hydrofluoric acid or potassium hydroxide and the like which are commonly used for processing chemical inert materials, and is environment-friendly, safe and reliable. Specifically, the electrolyte 400 may use NaNO in a mass fraction range of 0.5% to 20%3Aqueous solution, or aqueous NaCl solution.
In the plasma electrochemical jet composite processing method of the above embodiment, the position of the nozzle 100 is adjusted before processing so that the nozzle 100 and the workpiece 200 maintain the initial gap 500. In this embodiment, the initial gap 500 may be 0.2mm to 0.8mm, and may be configured accordingly according to different materials.
In the plasma electrochemical jet flow composite processing method of the above embodiment, the nozzle 100 having an inner diameter of 0.1mm to 2mm may be selected, and the stainless steel 304 material nozzle 100 may be selected. The nozzle 100 is connected to the electrolyte tank 110 through a pipe to continuously supply the electrolyte 400. The electrolyte 400 may be pumped to the nozzle 100 by an electrolyte pump. The piping may be provided with a pressure gauge to measure the pressure in real time, and the pressure of the electrolyte 400 may be adjusted to make the flow rate of the electrolyte 400 reach a set value, for example, the flow rate of the electrolyte 400 may be 3.8 m/s.
In the plasma electrochemical jet flow combined machining method according to the above embodiment, the electrolyte 400 injected from the nozzle 100 may be collected by the electrolytic cell, and the electrolytic cell may be communicated with the electrolyte tank 110, so that the electrolyte 400 in the electrolytic cell may be discharged into the electrolyte tank 110. An electrolyte 400 circulating device can be also arranged to realize the circulation of the electrolyte 400. Specifically, the jig may be placed in an electrolytic bath, so that when the workpiece 200 is clamped on the jig and machined, the electrolytic bath may be used to collect and discharge the electrolyte 400 sprayed from the nozzle 100, and the electrolyte 400 circulation device includes an electrolyte tank 110, a liquid feeding line, a liquid returning line, and a liquid feeding device, the nozzle 100 is communicated with the electrolyte tank 110 through the liquid feeding line, the liquid feeding device is disposed in the liquid feeding line, the liquid returning line is communicated with the electrolytic bath to discharge the electrolyte 400 in the electrolytic bath into the electrolyte tank 110, and the electrolyte 400 may be fed again to the nozzle 100 through the liquid feeding line, thereby realizing circulation of the electrolyte 400. The return line may be provided with a filter to separate the process waste from the electrolyte tank 110. An electrolyte pump can be connected to the liquid sending pipeline to pump the electrolyte to the nozzle 100, and the liquid sending pipeline can be further provided with a pressure gauge for monitoring the pressure in the liquid sending pipeline in real time so as to serve as a reference for adjusting the injection flow rate of the electrolyte 400.
In the plasma electrochemical jet combined machining method according to the above embodiment, the critical value of the voltage for generating the plasma discharge to break down the oxide film 230 is determined by factors such as the gap between the nozzle 100 and the workpiece 200 (gap between electrodes), the concentration of the electrolyte 400, and the material properties of the workpiece 200, and the specific value can be reasonably configured according to the actual machining material and the machining requirement. For example, for different chemically inert materials such as niobium, silicon, and silicon carbide, by changing the process parameters such as voltage, initial gap 500, and electrolyte 400 concentration, the plasma generation can be controlled to further remove the oxide film 230, and the method is suitable for processing various materials, and has the characteristics of flexibility and convenience in realizing selective removal of materials.
In the plasma electrochemical jet flow composite processing method of the above embodiment, by controlling the relative motion between the nozzle 100 and the workpiece 200 to be processed, a micro-groove structure can be conveniently processed on the surface of the material, and the surface patterning processing can be realized by further changing the motion trajectory.
In the plasma electrochemical jet flow composite processing method of the above embodiment, the workpiece 200 to be processed may be held by a jig, and the relative movement between the nozzle 100 and the workpiece 200 may be achieved by adjusting the relative movement between the nozzle 100 and the jig. During specific implementation, the movable workbench can be arranged, the clamp is arranged on the movable workbench, and the workpiece 200 can be moved through the position movement of the workbench, so that the mechanical adjustment of the position of the workpiece 200 is facilitated. The nozzle 100 can also be arranged on a driving mechanism, and the position of the nozzle 100 relative to the workpiece 200 can be adjusted by the driving of the driving mechanism, so that various processing motion tracks can be realized.
The following is a processing flow of a specific embodiment of the plasma electrochemical jet flow composite processing method, which substantially comprises the following steps:
s100: sequentially carrying out ultrasonic degreasing treatment on a workpiece to be processed in acetone and ethanol, then cleaning the workpiece with deionized water, drying the workpiece with compressed air, and clamping and accurately positioning the workpiece to be processed with a clamp;
s200: connecting a nozzle with an electrolyte pipeline, and adjusting the position of the nozzle to ensure that the initial gap between the nozzle and a workpiece to be processed is kept between 0.2mm and 0.8 mm;
s300: connecting a workpiece to be processed to the positive pole of a power supply, connecting a nozzle to the negative pole of the power supply, setting a constant voltage output mode of the power supply, wherein the voltage range is 100V-300V, the current waveform is direct current or pulse, and detecting a voltage and current signal in processing by adopting an oscilloscope probe;
s400: starting an electrolyte pump to spray electrolyte onto the surface of a workpiece to be processed through a nozzle, and adjusting the pressure of the electrolyte to enable the flow rate of the electrolyte to be 3.8 m/s;
s500: starting a power supply, controlling a processing motion track, and generating plasma discharge on the surface of a workpiece to break down an oxide film for material processing;
s600: and after the machining is finished, the power supply is turned off, the electrolyte pump is turned off, and the workpiece is taken out.
An embodiment of the present invention further provides a plasma electrochemical jet hybrid processing apparatus, fig. 3 is a schematic block diagram of the plasma electrochemical jet hybrid processing apparatus according to the embodiment of the present invention, fig. 4 is a schematic three-dimensional structure diagram of the plasma electrochemical jet hybrid processing apparatus according to the embodiment of the present invention, and referring to fig. 3 and fig. 4 in combination with fig. 2, the plasma electrochemical jet hybrid processing apparatus according to the embodiment of the present invention includes a rack and a spraying device, the rack is provided with a worktable 600, the worktable 600 is provided with a clamp 610 for clamping a workpiece 200 to be processed, and the clamp 610 may be a conventional three-jaw or four-jaw clamp 610. The spray device includes a nozzle 100, the nozzle 100 facing the jig 610, for spraying the electrolyte 400 toward the workpiece 200. The workpiece 200 to be processed is clamped on the clamp 610, the nozzle 100 is connected to the negative electrode 320 of the power supply, the workpiece 200 is connected to the positive electrode 310 of the power supply, the electrolyte 400 is sprayed on the surface of the workpiece 200 through the nozzle 100, and an electric field is applied between the nozzle 100 and the workpiece 200 through the power supply, so that the composite processing mode of electrolytic plasma processing and electrochemical jet processing is realized.
When the power is switched on, an oxide film is generated on the surface of the anode workpiece 200 in the processing area due to electrochemical oxidation-reduction reaction, so that the electrochemical reaction is prevented from continuing, meanwhile, oxygen is generated on the interface where the oxide film is contacted with the electrolyte 400, and when the electric potential between the two electrodes reaches a critical value, dielectrics such as the oxide film, the gas film and the like on the interface are broken down to form a discharge channel, so that the surface of the workpiece 200 is locally and instantaneously high in temperature and generates complex physical and chemical reactions, and further the selective processing of the surface is realized.
The plasma electrochemical jet flow composite processing device can be applied to the plasma electrochemical jet flow composite processing method of the embodiment, realizes a composite processing mode of electrolytic plasma processing and electrochemical jet flow processing, has a simple structure, is flexible and convenient to operate, and can effectively reduce the processing cost.
The plasma electrochemical jet flow combined processing device may further include a power supply device 300, wherein the positive electrode of the power supply device 300 is connected to the workpiece 200, and the negative electrode of the power supply device 300 is connected to the nozzle 100. The power supply device 300 outputs high voltage direct current, and the nozzle 100 is made of conductive material (e.g., metal nozzle 100). The power supply device 300 may be a device that takes power from the power grid, converts the power to one or more loads, or a battery-powered device that is onboard the processing device. In this embodiment, the power supply is set to be in a constant voltage output mode, the voltage range is 100V to 300V, and the specific value can be reasonably configured according to the actual processing material and the processing requirement. The waveform of the current outputted from the power supply is a dc waveform or a pulse waveform, and the power supply 300 is connected to a probe of the oscilloscope 330, and detects voltage and current signals during machining to monitor the current during machining.
The plasma electrochemical jet composite processing device of the above embodiment may further include a driving device, the driving device is connected to the frame, and is used for driving the workbench 600 and the nozzle 100 to move relatively, so as to realize the relative movement between the workpiece 200 to be processed and the nozzle 100, adjust the gap between the nozzle 100 and the workpiece 200 before processing, and adjust the processing track during processing, so as to realize patterned scanning processing such as micro-grooves.
Specifically, the driving device may perform motion control of X, Y, Z axes in three directions (illustrated in the figure by a conventional X, Y, Z rectangular spatial coordinate system), for example, the driving device may include a first driving part 710, a second driving part 720 and a third driving part 730, wherein the first driving part 710 is connected to the injection device and is used for driving the injection device to move along the Z-axis, so as to realize the motion of the nozzle 100 along the Z-axis; the second driving part 720 is connected to the first driving part 710 and is used for driving the first driving part 710 and the injection device to move along the X-axis, so as to realize the movement of the nozzle 100 along the X-axis; the third driving part 730 is connected to the table 600 and serves to drive the table 600 to move along the Y-axis, thereby achieving movement of the workpiece 200 to be processed along the Y-axis. Thus, the relative motion between the nozzle 100 and the workpiece 200 can be adjusted in three directions about the X, Y, Z axis. The first driving unit 710, the second driving unit 720 and the third driving unit 730 may be a linear motor, a cylinder, or other conventional power elements.
In other embodiments, the motion adjustment in the X, Y axis direction may be configured on the table 600, and the spraying device only performs the motion control in the Z axis direction, specifically, the table 600 may be configured as a X, Y axis motion platform, the spraying device is connected to a Z axis motion mechanism, that is, a driving mechanism is configured to drive the table 600 to move along the X, Y axis, and another driving mechanism is configured to drive the spraying device to move along the Z axis, so that the motion of the workpiece 200 to be processed in the X, Y axis direction and the motion of the nozzle 100 in the Z axis direction can be achieved, and the adjustment of the relative motion between the nozzle 100 and the workpiece 200 in the X, Y, Z axis three directions can also be performed.
In other embodiments, a three axis robot may be used to manipulate the nozzle 100 to make X, Y, Z axis three direction adjustments, while the stage is stationary relative to the gantry, and three axis X, Y, Z axis three direction adjustments of relative motion between the nozzle 100 and the workpiece 200 may be achieved.
In the plasma electrochemical jet combined processing device of the above embodiment, the worktable 600 may further be provided with an electrolytic cell 620, the clamp 610 is disposed in the electrolytic cell 620, the electrolyte 400 sprayed by the nozzle 100 may be collected by the electrolytic cell 620, and the electrolytic cell 620 is communicated with the electrolyte tank 110, so that the electrolyte 400 in the electrolytic cell 620 is discharged to the electrolyte tank 110. An electrolyte 400 circulating device can be also arranged to realize the circulation of the electrolyte 400.
Specifically, the jig 610 may be placed in the electrolytic bath 620, and when the workpiece 200 is clamped on the jig 610 for machining, the electrolytic bath 620 may be configured to collect and discharge the electrolyte 400 sprayed from the nozzle 100, the electrolyte 400 circulating device may include the electrolyte tank 110, the liquid sending pipe 120, the liquid return pipe 130, and the liquid sending device 140, the nozzle 100 may be connected to the electrolyte tank 110 through the liquid sending pipe 120, and the liquid sending device 140 may be an electrolyte pump configured to pump the electrolyte. The wall or bottom of the electrolytic cell 620 may be provided with a liquid outlet, and the liquid return pipeline 130 is connected to the liquid outlet of the electrolytic cell 620, and is used for discharging the electrolyte 400 in the electrolytic cell 620 into the electrolyte tank 110, and can be sent to the nozzle 100 again through the liquid sending pipeline 120, so as to realize circulation of the electrolyte 400. A filter 150 may be disposed on the return line 130 to separate process waste from the electrolyte tank 110. An electrolyte pump may be connected to the liquid feeding line 120 to pump the electrolyte to the nozzle 100, and the liquid feeding line 120 may further be provided with a pressure gauge 160 for monitoring the pressure in the liquid feeding line 120 in real time, so as to serve as a reference for adjusting the injection flow rate of the electrolyte 400.
In the above embodiment, the nozzle 100 may be a metal nozzle 100 with an inner diameter of 0.1mm to 2mm, the nozzle 100 may be made of stainless steel 304, and the electrolyte 400 may be NaNO with a mass fraction of 0.5% to 20%3Aqueous solution, or other neutral salt solution such as aqueous NaCl solution. The flow rate of the electrolyte 400 may be set such that the flow rate of the electrolyte 400 is 3.8m/s, and the initial gap 500 between the adjusting nozzle 100 and the workpiece 200 to be processed may be 0.2mm to 0.8mm before processing.
The plasma electrochemical jet flow composite processing device can also comprise a Controller which is electrically connected with the composite processing device, particularly, the Controller is used for controlling the operation of an electric device in the composite processing device, can be a Programmable Logic Controller (PLC), a single chip microcomputer, a time control switch, a micro processing terminal and the like, and can realize the driving of a nozzle and/or a workbench, the on-off of a power supply, the on-off of a liquid feeding device and the like through a preset scheme so as to realize the ordered operation of the electric device. Meanwhile, the controller can collect and process data (such as pressure gauge and oscilloscope data) of the sensor and the instrument in the system, and the data are used for feeding back the running state of the system and providing basis for system regulation and control. The process and method for controlling the controller can be easily implemented by those skilled in the art, for example, a PLC uses a programmable memory, stores therein instructions for performing operations such as logic operation, sequence control, timing, counting, and arithmetic operation, and controls various types of mechanical devices or manufacturing processes through digital or analog input/output. Belongs to the prior art and is not the essential point of the invention, and the description is not repeated herein.
The plasma electrochemical jet flow composite processing device comprises the following steps of:
firstly, placing a workpiece to be processed in an electrolytic bath of a machine tool, clamping the workpiece by using a clamp and accurately positioning the workpiece, wherein the workpiece to be processed can be pretreated firstly: sequentially carrying out ultrasonic degreasing treatment in acetone and ethanol, then cleaning with deionized water and drying with compressed air;
secondly, mounting a metal nozzle on a main shaft of the machining device, connecting the nozzle with an electrolyte pipeline, and adjusting the position of the nozzle to keep an initial gap between the nozzle and a workpiece to be machined;
connecting the workpiece to be processed to the anode of a power supply device, connecting a nozzle to the cathode of the power supply device, setting a constant voltage output mode of the power supply device, wherein the voltage range is 100V-300V, the current waveform is direct current or pulse, and detecting a voltage and current signal in processing by adopting an oscilloscope probe;
fourthly, starting an electrolyte pump to spray electrolyte onto the surface of the workpiece to be processed through a nozzle, and adjusting the pressure of the electrolyte to enable the flow rate of the electrolyte to be 3.8 m/s;
fifthly, starting a power supply of the driving device, controlling the relative motion of the workpiece and the nozzle to adjust the processing motion track, and generating plasma discharge on the surface of the workpiece to break down the oxide film for material processing;
and sixthly, turning off the power supply of the driving device after the machining is finished, turning off the electrolyte pump, and taking out the workpiece.
Two specific application examples of the plasma electrochemical jet flow compound processing method and the plasma electrochemical jet flow compound processing device provided by the embodiment of the invention are as follows:
taking a chemically inert semiconductor material of silicon carbide as an example, fig. 5 is a schematic diagram of oxide film formation on the surface of the chemically inert semiconductor silicon carbide, fig. 6 is a schematic diagram of material removal in fig. 5, 1 μm marked at the lower left corner in fig. 5 and 200 μm marked at the lower left corner in fig. 6 are scales, fig. 7 is a schematic diagram of a change process from an anodic oxidation area to a plasma discharge area under different process parameters, and the ordinate represents current density (a/cm)2) The abscissa represents voltage (V), curve L1 represents Si (0.001-0.01. omega. cm), and curve L2 represents Nb (1.25X 10)-9Ω · cm), and curve L3 represents SiC (0.015 to 0.028 Ω · cm). Referring to fig. 5 to 7, the workpiece to be processed in the specific processing is an n-type 4H-SiC (0001) sample, the size is 10 × 10mm, the thickness is 350 μm, the resistivity is 0.015 to 0.028 Ω · cm, and the surface is subjected to chemical mechanical polishing treatment. Prior to the experiment, the samples were sequentially treated by ultrasonic degreasing in acetone and ethanol, then washed with deionized water and dried using compressed air. The cathode is a stainless steel 304 nozzle with an inner diameter of 0.31mm, and the electrolyte is NaNO with a certain mass fraction3The mass fraction range of the aqueous solution is 0.5-20%, the flow rate of the electrolyte is 3.8m/s, the initial gap of the electrode is 0.2-0.8 mm, the power supply adopts a constant voltage output mode, the voltage range is 200-300V, the current waveform is direct current or pulse, and an oscilloscope probe is adopted to obtain a voltage current signal. As can be seen from the comparison between FIG. 5 and FIG. 6, at 200V, the electrochemical anodic oxidation process occurs on the surface, when the voltage is continuously increased to reach the critical value, the plasma discharge can be generated to break down the oxide film, and the micro-processing of the chemically inert material can be realized under the thermal action mechanism. As shown in FIG. 6, under the condition of 220V voltage and 14s processing time, plasma discharge is generated to break down the oxide film to remove the material, so as to leave a radial crater, the diameter of the crater and the affected area thereof is 633 μm and is about 2 times of the diameter of the nozzle, and the dotted line in the figure represents the affected area of the crater. As can be seen from fig. 7, the electrolyte mass fraction was 20 wt.%, the initial machining gap was 200 μm, and the current density linearly increased with an increase in voltage in the anodic oxidation zone S1. Above a certain voltage threshold, a plasma discharge occurs and the current density rises at a higher rate, as shown by the curved plasma discharge region S2. Depending on the electrolyte concentration, the respective threshold voltages separating the two regions lie in the range 200V to 260V and a higher electrolyte concentration corresponds to a lower threshold voltage.
Taking chemically inert semiconductor silicon and metallic niobium as an example, fig. 8 to 11 are some examples of micro-groove patterns machined on the surfaces of chemically inert semiconductor silicon and metallic niobium, wherein 200 μm and 400 μm marked at the lower left corner are scales; during specific processing, a micro-groove pattern structure is processed on the surface of a material by controlling the relative motion between the metal nozzle and a workpiece to be processed. The anode workpiece is a p-type Si (100) sample during processing, the size is 10 multiplied by 10mm, the thickness is 460 mu m, the resistivity is 0.001-0.01 omega-cm, and the surface is subjected to chemical mechanical polishing treatment; the niobium specimen had a size of 10X 10mm, a thickness of 400 μm and a resistivity of 1.25X 10-9Omega cm. Prior to the experiment, the samples were sequentially treated by ultrasonic degreasing in acetone and ethanol, then washed with deionized water and dried using compressed air. The cathode is a stainless steel 304 nozzle with an inner diameter of 0.31mm, and the electrolyte is NaNO with a mass fraction of 20%3The flow rate of the electrolyte in the water solution is 3.8m/s, the initial gap of the electrode is 200 μm, the power supply adopts a constant voltage output mode, the voltage is 160V, and the relative movement speed between the metal nozzle and the workpiece to be processed is 0.3 mm/s. Fig. 8 and 10 show that micro-grooves with better dimensional accuracy are obtained on the silicon surface by using the method, and fig. 9 and 11 show that micro-grooves are obtained on the niobium surface by using the method.
According to the plasma electrochemical jet flow combined machining method and the plasma electrochemical jet flow combined machining device, continuous discharge of plasma is generated on the surface of a workpiece electrode through voltage induction, and newly generated oxide films are continuously removed through charged particles in the plasma, so that the localized and efficient removal of chemical inert materials is realized, and the plasma electrochemical jet flow combined machining method and the plasma electrochemical jet flow combined machining device have good application prospects and advantages. The plasma electrochemical jet flow compound processing method and the device can be applied to compound electrolytic machining machines, superconducting magnetic suspension equipment, gas turbine engines, surgical operation equipment, power semiconductor devices and the like.
The embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the gist of the present invention. Furthermore, the embodiments of the present invention and the features of the embodiments may be combined with each other without conflict.
Claims (10)
1. The plasma electrochemical jet flow composite processing method is characterized by comprising the following steps: spraying electrolyte to a workpiece to be processed by a nozzle of a spraying device in an electrochemical jet mode through the spraying device, applying an electric field between the nozzle and the workpiece, and generating plasma on the surface of the workpiece at a set voltage to break down an oxide film generated by the electrochemical jet so as to remove the surface material of the workpiece.
2. A plasma electrochemical jet combined machining method as claimed in claim 1, wherein the electric field is applied between the nozzle and the workpiece by: the workpiece is connected to a positive power supply and the nozzle is connected to a negative power supply.
3. A plasma electrochemical jet flow compound processing method as claimed in claim 2, characterized in that the power supply is set to a constant voltage output mode, the output current waveform is a direct current waveform or a pulse waveform, and the voltage range is 100V to 300V.
4. A plasma electrochemical jet combined machining method according to claim 1, characterized in that the initial gap between the nozzle and the workpiece is 0.2mm to 0.8 mm.
5. A plasma electrochemical jet recombination processing method as claimed in claim 1, wherein the electrolyte is a neutral salt solution.
6. A plasma electrochemical jet combined processing method as claimed in claim 5, wherein the electrolyte is NaNO with a mass fraction ranging from 0.5% to 20%3The electrolyte is an aqueous solution of NaCl.
7. A plasma electrochemical jet machining method as claimed in any one of claims 1 to 6, characterized in that the trajectory of the nozzle relative to the surface of the workpiece is controlled to machine a desired position for localized material removal.
8. Plasma electrochemical jet flow combined machining device is characterized by comprising:
the machining device comprises a rack, wherein a workbench is arranged on the rack, and a clamp for clamping a workpiece to be machined is arranged on the workbench;
the spraying device comprises a nozzle, the nozzle faces the clamp and is used for spraying electrolyte to the workpiece;
and the anode of the power supply device is connected with the workpiece, and the cathode of the power supply device is connected with the nozzle.
9. A plasma electrochemical jet composite processing apparatus as claimed in claim 8, further comprising a drive device connected to said frame for driving relative movement of said stage and said nozzle.
10. A plasma electrochemical jet combined machining apparatus according to claim 8 or 9, wherein an electrolytic bath is further provided on the table, the jig being placed in the electrolytic bath, the electrolytic bath being configured to collect and discharge the electrolyte ejected from the nozzle.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115036216A (en) * | 2022-05-19 | 2022-09-09 | 南方科技大学 | Silicon carbide nano-porous etching method and etching device |
| CN115625627A (en) * | 2022-11-09 | 2023-01-20 | 大连理工大学 | SiC wafer photoelectrochemical mechanical polishing device and method based on vacuum conductive sucker |
| CN117265628A (en) * | 2023-09-18 | 2023-12-22 | 广州航海学院 | High-voltage jet electrolytic machining device and method based on plasma discharge |
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2020
- 2020-12-22 CN CN202011525978.1A patent/CN112676780A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115036216A (en) * | 2022-05-19 | 2022-09-09 | 南方科技大学 | Silicon carbide nano-porous etching method and etching device |
| CN115625627A (en) * | 2022-11-09 | 2023-01-20 | 大连理工大学 | SiC wafer photoelectrochemical mechanical polishing device and method based on vacuum conductive sucker |
| CN117265628A (en) * | 2023-09-18 | 2023-12-22 | 广州航海学院 | High-voltage jet electrolytic machining device and method based on plasma discharge |
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