JP6630015B2 - Surface treatment method and surface treatment device - Google Patents

Description

  The present invention relates to a surface treatment method and a surface treatment apparatus for performing a surface treatment on an object to be treated. More specifically, a surface treatment method and a surface treatment apparatus for forming an oxide film on a treatment surface of a treatment object made of a valve metal such as aluminum, tantalum, niobium, titanium, hafnium, zirconium, zinc, tungsten, bismuth, and antimony About. The valve metal is also called a valve metal or a valve metal.

  As shown in FIG. 7, a surface treatment method for forming an oxide film on the surface of the object to be processed by performing an anodic oxidation process including a micro-arc oxidation process on the object to be processed 111 having a small area is known. In FIG. 7, reference numeral 121 denotes an electrolytic solution tank, and reference numeral 122 denotes an electrolytic solution. When the processing target 111 has a small area, an oxide film may be formed by immersing the entire processing target 111 in the electrolyte solution 122. However, as the object to be processed 111 becomes larger in area, in the method shown in FIG. 7, that is, in the anodic oxidation treatment including the micro-arc oxidation treatment requiring a high voltage and a high current density, facilities such as a power supply and a chiller And it becomes difficult to process a large-sized object to be processed.

  In order to solve this problem, an oxide film is formed on the entire surface of the object to be processed by dividing the surface of the object to be processed having a large area and performing anodic oxidation including micro-arc oxidation in a plurality of times. The present inventor has previously proposed a surface treatment method to be performed (Patent Document 1). Here, the micro-arc oxidation treatment (anodic oxidation treatment involving spark discharge) is a kind of anodic oxidation treatment and means a surface treatment method capable of forming an excellent oxide film. However, the method disclosed in Patent Literature 1 has a problem in that work efficiency is poor because there is a step of removing a mask material by lifting an object to be processed from an electrolytic solution.

  In order to solve the problem in the method of Patent Document 1, the present inventors have further proposed a method of performing a surface treatment without using a mask (Patent Document 2). Thereby, the step of removing the mask material is not required, and the working efficiency is improved. However, in the method disclosed in Patent Literature 2, a stripe pattern remains on the processing surface of the object to be processed, and improvement in the appearance of the processing surface has been demanded.

Therefore, the present inventor studied a method of performing micro-arc oxidation treatment on an object to be processed of several m ² without dividing the surface of the object to be processed having a large area. In the case of the micro-arc oxidation treatment (anodic oxidation treatment with spark discharge), the treatment is performed at a higher current density and a higher voltage than in the normal anodic oxidation treatment without spark discharge. For this reason, when an oxide film is formed on an object to be processed having a large processing area by the micro-arc oxidation process, a large-scale power supply facility, a large-sized electrolyte cooling mechanism, and the like are required, and the facility is costly. There was a problem.

Japanese Patent No. 4836921 Japanese Patent No. 5770575

  The present invention has been made in view of the above circumstances, and even with a small-current power supply device and a simple electrolyte cooling mechanism, a large area can be covered by anodic oxidation treatment including micro-arc oxidation treatment. An object of the present invention is to provide a surface treatment method and a surface treatment apparatus capable of forming an oxide film intermittently on a treated body.

In order to solve the above problems, the present invention has provided the following surface treatment method and surface treatment apparatus. That is,
A surface treatment apparatus for performing an anodic oxidation process including a micro-arc oxidation process by immersing an object to be processed made of a valve metal in an electrolytic solution to form an oxide film on the object to be processed,
Anode means for forming the oxide film by the anodic oxidation treatment on the surface of the object to be processed,
An electrolyte bath containing the electrolyte, and having an opening that allows the anode means to be immersed in the electrolyte,
Cathode means arranged opposite to the anode means in the electrolytic solution,
In the state where the anode means and the cathode means are immersed in the electrolytic solution, a predetermined voltage is applied to generate a current I between the anode means and the cathode means to perform the anodic oxidation treatment. Power supply means,
The object to be processed is moved in the depth direction of the electrolytic solution in order to immerse the processing object in the electrolytic solution up to a specific processing section, and the specific processing section is immersed in the electrolytic solution. The object to be processed is provided with a function of stopping the object to be immersed at the position where the object is immersed. Movement in the depth direction of the electrolytic solution, moving means of the object to be processed,
A control device for controlling the power supply means and the moving means,
Including
The moving means applies a predetermined voltage over the entire area of the object to be processed, and every time a series of anodic oxidation processes is completed, from the electrolytic solution to a position where the entire area of the object to be processed is exposed. Is configured to move the anode means in a direction to pull up the object to be processed from the electrolytic solution ,
The control unit repeats performing an anodic oxidation process over the entire area of the object to be processed (M-th step) ;
It is characterized by the following.
In the present invention, the control device includes:
While repeating the M-th step which is an anodic oxidation treatment over the entire area of the object,
Each time the first M step is anodized a predetermined voltage is applied to V _M is finished, in the next M th step, a function of applying a predetermined voltage higher than the voltage V _M to the workpiece Prepare,
It is characterized by the following.
In the present invention, the controller compares the current value I and the predetermined current value I ₁ at the time of the anodic oxidation treatment,
When the relationship between the current value I during the anodic oxidation treatment and the predetermined current I ₁ satisfies “I ₁ ≧ I”, the object is moved in the depth direction of the electrolytic solution,
Current value I during the anodic oxidation treatment, if it exceeds the predetermined current value I ₁ is a function to quiesce the object to be processed,
It is characterized by the following.

The present invention sets a plurality of processing sections on a processing surface of a processing target made of a valve metal, performs anodic oxidation processing including micro-arc oxidation processing by immersing each processing section intermittently in an electrolytic solution, A surface treatment method for forming an oxide film on the surface to be treated,
The anodic oxidation treatment includes an M step including a plurality of steps of moving the object to be processed in each of the processing sections having a width in a depth direction of the electrolytic solution,
The M-th step is:
Said only the first processing compartment is immersed in the electrolytic solution of the object to be processed, held to a low voltage V _M than the maximum voltage V _max of the anodic oxidation treatment, so as to have a predetermined current I _1, the Continuing with the step of forming the desired oxide layer in the first processing zone,
The workpiece having been subjected to the immediately preceding step, it was immersed in the electrolyte to the processing compartment adjacent to said processing compartment have been processed, between the first and last in the previous step and the same voltage V _M Conditions Repeating the step of forming a desired oxide film on the processing section,
Until the end of the treatment compartment is immersed in the electrolyte, by performing the step of forming the desired oxide film on the end of the processing compartment with the same voltage V _M conditions the previous step, and held in the voltage V _M An oxide film is formed over the entire surface to be processed,
Further, the M-th step is a step that is repeatedly performed a plurality of times,
The first of the M step of performing a voltage of the anodic oxidation treatment at a voltage V _M, between a voltage of the anodic oxidation treatment to the end of the M step carried out at the maximum voltage V _max, the voltage of the anodic oxidation treatment the from the voltage V _M to be stepwise increased until the maximum voltage V _max, to form the oxide film in which the total film thickness over the entire treated surface is made of a desired thickness,
be able to.

In the present invention, in the above, the repetition of the M-th step may be 2 or more.
The present invention, in the above, the value of the predetermined current at the time of repeatedly performing the first M step is the same as the current I _1, it is possible.
In the present invention, in the above, when the plurality of processing sections in the object to be processed are sequentially immersed in the electrolytic solution, the object proceeds or stops in a depth direction of the electrolytic solution. In addition, the position of the object to be processed with respect to the level of the electrolytic solution can be controlled.
The present invention continues from the above-mentioned last M-th step,
The final low voltage V to _M- than the M step the voltage V _M made, continuously or intermittently lowers the voltage at a predetermined time, a step P of performing the anodic oxidation treatment,
A step Q of performing a constant voltage process at the voltage _VM− may be further provided in order.
The present invention is a surface treatment apparatus for performing an anodic oxidation treatment by the surface treatment method described above, and forming an oxide film on the object to be treated,
Anode means for forming the oxide film by the anodic oxidation treatment on the surface of the object to be processed,
An electrolyte bath containing the electrolyte, and having an opening that allows the anode means to be immersed in the electrolyte,
Cathode means arranged opposite to the anode means in the electrolytic solution,
In a state in which the anode means and said cathode means is immersed in the electrolyte, the by generating a current I ₁ between the anode means and said cathode means, and power supply means for performing the anodic oxidation treatment,
The object to be processed is moved in the depth direction of the electrolytic solution in order to immerse the processing object in the processing section up to a specific processing section in the electrolytic solution, and the processing section is up to the specific processing section. A moving means of the object to be processed having a function of stopping the object to be processed at a position immersed in the electrolytic solution,
The moving means moves the object from the electrolytic solution to a position where the entire area of the object is exposed from the electrolytic solution every time the M-th step over the entire area of the object is completed. It can be configured to move the anode means in the lifting direction.
The present invention is a surface treatment apparatus for performing an anodic oxidation treatment by the surface treatment method described above, and forming an oxide film on the object to be treated,
Anode means for forming the oxide film by the anodic oxidation treatment on the surface of the object to be processed,
An electrolyte bath containing the electrolyte, and having an opening that allows the anode means to be immersed in the electrolyte,
Cathode means arranged opposite to the anode means in the electrolytic solution,
In the state where the anode means and the cathode means are immersed in the electrolytic solution, a current is generated between the anode means and the cathode means, and a power supply means for performing the anodic oxidation treatment,
The object to be processed is moved in the depth direction of the electrolytic solution in order to immerse the object up to a specific processing section in the electrolytic solution, and the predetermined current value I ₁ and the processing current comparing a value, wherein the moving means of the object to be processed having a function to quiesce the workpiece when it exceeds the predetermined current value I _1,
The moving means moves the object from the electrolytic solution to a position where the entire area of the object is exposed from the electrolytic solution every time the M-th step over the entire area of the object is completed. It is configured to move the anode means in the pulling-up direction, and in the Mth step next to the Mth step, a voltage higher than the predetermined voltage is applied to the object as a predetermined voltage, be able to.

In the present invention, a plurality of processing sections are set on a processing surface of a processing object made of a valve metal, and anodizing treatment is performed by intermittently immersing the processing section in an electrolytic solution for each processing section. A surface treatment method for forming an oxide film,
The anodic oxidation treatment includes an M-th (M is an integer of 2 or more) step,
The M-th step is:
Said only the first processing compartment of the object to be processed is immersed in the electrolyte solution, and held at the maximum voltage V _max voltage lower than V _M of the anode oxidation process comprising micro-arc oxidation process, a predetermined current I ₁ A Ma step of forming a desired oxide film on the first processing section of the object to be processed;
The object to be processed after the Ma step is immersed in the electrolytic solution up to the second processing section adjacent to the first processing section, and a desired oxide film is formed on the second processing section under the same conditions as in the Ma step. Forming an Mb step;
The object to be processed after the Mb step is immersed in the electrolytic solution up to the n-th processing section to form a desired oxide film on the n-processing section under the same conditions as in the Ma step. Mn-th step (n is an integer of 1 or more) of forming an oxide film over the entire area,
Said voltage V _M is increased in order in the direction of the highest voltage V _max is a predetermined number, by repeating the first M step to form the oxide film total thickness is composed of a desired thickness, it Can be.
In the above, according to the present invention, in the anodic oxidation treatment, the n is 1, and the Mth step, the Mth step,... The body can be immersed in the electrolyte continuously or intermittently.
The present invention, in the above, the second Mb step, the value of the predetermined current in ... the first Mn step may be the same as the predetermined current I ₁ in the first Ma step.
In the above, when the first processing section, the second processing section, and the n-th section in the object to be processed are sequentially immersed in the electrolytic solution, the present invention may be applied in a depth direction of the electrolytic solution. The position of the target object with respect to the level of the electrolytic solution can be controlled so that the target object advances or stops.
The present invention, in the above, in order to control the position of the object to be processed with respect to the liquid level of the electrolytic solution, fixing the height position of the liquid level of the electrolytic solution, the liquid level of the electrolytic solution The height position of the object to be processed can be adjusted.
The present invention, in the above, in order to control the position of the object to be processed with respect to the liquid surface of the electrolytic solution, fixing the height position of the object to be processed, the height position of the object to be processed The height of the electrolyte surface can be adjusted.
The present invention is, following the end of the M step in the said last low voltage V to _M- than the M step the voltage V _M performed, continuously or intermittently voltage at a predetermined time The method may further include, in order, a step P of lowering the anodic oxidation treatment and a step Q of performing a constant voltage treatment at the voltage _VM− .

The present invention is a surface treatment apparatus for performing an anodic oxidation treatment by immersing an object to be processed made of a valve metal in an electrolytic solution to form an oxide film on the object to be processed,
Anode means for forming the oxide film by anodic oxidation treatment on the surface of the object to be processed,
An electrolyte bath containing the electrolyte, and having an opening that allows the anode means to be immersed in the electrolyte,
Cathode means arranged opposite to the anode means in the electrolytic solution,
In the state where the anode means and the cathode means are immersed in the electrolytic solution, a current is generated between the anode means and the cathode means, and a power supply means for performing the anodic oxidation treatment,
The object to be processed is moved in the depth direction of the electrolytic solution in order to immerse the processing object in the electrolytic solution up to a specific processing section, and the specific processing section is immersed in the electrolytic solution. Means for moving the object to be processed having a function of resting the object at the immersed position,
The moving means applies a predetermined voltage over the entire area of the object to be processed, and every time a series of anodic oxidation processes is completed, from the electrolytic solution to a position where the entire area of the object to be processed is exposed. The anode means may be configured to be moved in a direction in which the object to be processed is pulled up from the electrolytic solution.

According to the surface treatment method according to the present invention, the treated surface of the object to be processed is, intermittent oxidation (maintained at a low voltage V _M than the maximum voltage V _max of the micro-arc oxidation process, a predetermined current I ₁ The above-described M-th step (the M-th step is repeated two or more times) is performed so as to be covered with the oxide film. Further, said voltage V _M is increased in order in the direction of the highest voltage V _max is a predetermined numerical V _{M + n,} by repeating the first M step, the oxidation final thickness consists of desired thickness Form a coating. As a result, the present invention can intermittently apply to a large-area workpiece by anodic oxidation including micro-arc oxidation even with a power supply device having a small current density and a simple electrolyte cooling mechanism. This contributes to the provision of a surface treatment method capable of forming an oxide film.
Moreover, the treated surface of the object to be processed by the surface treatment method of the present invention, by holding to a low voltage V _M than the maximum voltage V _max during formation of the oxide film, and a predetermined current I _1, intermittently Even if the processing is performed, a color pattern does not remain on the processing surface. For this reason, it becomes possible to obtain an oxide film excellent in uniformity of the appearance of the treated surface.
In the surface treatment method of the present invention, in the anodic oxidation treatment, the repetition of the M-th step is two or more, and the step of configuring the M-th step includes continuously or intermittently treating the object to be treated. It can also be immersed in an electrolytic solution. At that time, the value of the predetermined current at the first M step is the same value at a predetermined current I _1.
In the surface treatment method of the present invention, in the anodic oxidation treatment, the n is 1, and the Mth step, the Mth step, the Mb step,... The object may be continuously or intermittently immersed in the electrolytic solution. At that time, the second Mb step, the value of the predetermined current in ... the first Mn step is the same value as the predetermined current I ₁ in the first Ma step.

The surface treatment apparatus according to the present invention moves the object to be processed in the depth direction of the electrolytic solution in order to immerse the object to be processed to a specific treatment section in the electrolytic solution, and performs the specific treatment. There is provided a moving means of the object having a function of stopping the object at a position where the section is immersed in the electrolytic solution. Then, the moving unit applies a predetermined voltage over the entire area of the object to be processed, and every time a series of anodic oxidation processes is completed, the entire area of the object to be processed is exposed from the electrolytic solution. The anode means is configured to be moved to a position where the object is pulled up from the electrolyte. Thus, according to the present invention, since it is possible to retain the current at the anode oxidation process comprising micro-arc oxidation process in a predetermined current I ₁ or less, large-capacity power supply is not required. Furthermore, since the heat generation during the formation process of all oxide films can be positively reduced, the size of the system for cooling the processing system can be reduced as compared with the related art.
Therefore, the present invention is to form an oxide film intermittently on an object to be processed having a large area by micro-arc oxidation, even with a power supply device having a small current density and a simple electrolyte cooling mechanism. To provide a possible surface treatment device.
Further, since the surface treatment apparatus of the present invention is provided with the above-described anode means, an oxide film having a desired film thickness is formed on a large-sized workpiece so as to automatically cover the workpiece. it can.

FIG. 1 is a block diagram showing a surface treatment apparatus according to the present invention. 5 is a flowchart illustrating a surface treatment method according to the present invention. Explanatory drawing which shows the surface treatment method concerning this invention. 5 is a graph showing a relationship between voltage and current and processing time, and is a voltage-current curve when the processing is performed by the method of the present invention. 4 is a graph showing a relationship between a voltage and a current and a processing time, and is a voltage-current curve when the processing is performed collectively. The batch processing is a method in which the entire surface (the entire surface) of the object to be processed is simultaneously immersed in the electrolytic solution to perform the processing. 5 is a graph illustrating a relationship between a position of a processing target in a immersion direction and a processing time. Explanatory drawing which shows the conventional surface treatment method.

  Hereinafter, best modes of a surface treatment apparatus and a surface treatment method according to the present invention will be described with reference to the drawings. The embodiment is specifically described for better understanding of the spirit of the invention, and does not limit the invention unless otherwise specified.

FIG. 1 is a block diagram showing a surface treatment apparatus according to the present invention.
As shown in FIG. 1, the surface treatment apparatus of the present invention performs a anodic oxidation treatment by immersing a treatment target 11 made of aluminum or an aluminum alloy in an electrolytic solution 22 to form an oxide film on the treatment target. Processing device.
In this surface treatment apparatus, the object to be treated 11 on which an oxide film is formed by anodic oxidation functions as anode means.

In this surface treatment apparatus, the electrolytic solution tank 21 for storing the electrolytic solution 22 is provided with an opening that allows the anode means (the object to be processed 11) to be immersed in the electrolytic solution.
In the electrolytic solution 22, the cathode means 17 is disposed at a position facing the immersed anode means (the object to be processed 11).
The surface treatment apparatus of the present invention includes a power supply means 30 for performing the anodic oxidation treatment. The power supply means 30 generates a current between the anode means (the object 11) and the cathode means 17 in a state where the anode means (the object 11) and the cathode means 17 are immersed in the electrolytic solution 22. And the anodic oxidation treatment is performed.

  The surface treatment apparatus of the present invention includes a moving unit (for example, an actuator) 40 for moving the object to be treated 11. The moving unit 40 holds the object 11 via the first support 41 and the second support 42. The moving means 40 has a function of moving the processing target 11 in the depth direction (Z direction) of the electrolyte 22 in order to immerse the processing target 11 up to a specific processing section in the electrolyte 22. A function of stopping the object to be processed 11 at a position where a part up to a specific processing section is immersed in the electrolytic solution 22.

  In other words, the moving means 40 connects the first support portion 41 which can be moved up and down, the other end of the first support portion 41 and the upper end of the processing target 11, and sets the processing target 11 in a state where the processing target 11 is suspended. A second support portion 42 is provided for keeping. As a result, the object 11 is subjected to a series of anodic oxidation treatments by applying a predetermined voltage over the entire area thereof (all areas in the direction (Z direction) in which the object 11 is immersed in the electrolytic solution 22). It can be performed. In addition, every time the series of anodic oxidation treatments is completed, the moving unit 40 pulls the object 11 up from the electrolyte 22 to a position where the entire area of the object 11 is exposed from the electrolyte 22. The anode means (the object to be processed 11) is configured to move.

  The vertical movement of the moving means 40 is controlled by the information processing device 60 via the sequencer 50. The information processing device 60 controls information (voltage and current) applied from the power supply unit 30 to the anode unit (the object to be processed 11) and the cathode unit 17 through a communication line. FIG. 1 shows a configuration example in which the sequencer 50 and the information processing device 60 are divided and arranged, but a control device integrating these components may be used (not shown). It is preferable that the control unit of the control device includes a comparison unit having a function of comparing the above-described predetermined current value with the processing current value.

FIG. 2 is a flowchart showing the surface treatment method according to the present invention. FIG. 3 is an explanatory diagram showing a surface treatment method according to the present invention. In the description based on FIG. 3 below, in the anodic oxidation process, the number of the steps is “3 or more”, and the MA step (the M-step is repeated 2 or more) constitutes the MA step ( Step),... The case where the MN step (step) immerses the object to be processed “intermittently” in the electrolytic solution will be described in detail.
In the surface treatment method according to the present invention, a plurality of treatment sections A, B, C,... N are set on the treatment surface of the treatment object 11 made of aluminum or an aluminum alloy (FIG. 3A). Anodizing is performed by intermittently immersing in an electrolytic solution for each processing section to form an oxide film on the surface to be processed. Here, “intermittently” means that first the processing section A, then the processing section B, then the processing section C, and finally the processing section N (that is, the processing target 11). Of the surface to be treated) is sequentially immersed in the electrolytic solution to perform the anodic oxidation treatment.
In FIG. 3A, x1 represents the width of the processing target 11, x2 represents the height of the processing target 11, and x3 represents the thickness of the processing target 11, respectively.

The anodic oxidation treatment in the surface treatment method of the present invention includes an M-th step (M is an integer of 2 or more) described later. That is,
The M-th step (M is an integer of 2 or more) includes an MA-th step (step), an MB-th step (step), an MC-th step (step),... Is done.

In the MA-th step (step), the processing target 11 is moved in the Z direction by a distance Δa. Thus, only the first processing section A of the processing target 11 is immersed in the electrolytic solution 22. While maintaining this immersed state, as held in the maximum voltage V _max low voltage V _M than the anodic oxidation process including micro-arc oxidation process, a predetermined current I _1, a first processing of the object 11 A desired oxide film is formed in section A [FIG. 3 (b) → FIG. 3 (c): MA-th step (step)]. 3 (b) and 3 (c), the symbol Δa is the width of the first processing section A in the Z direction. In FIG. 3C, reference numeral 15a1 denotes an oxide film formed in the first processing section A. Here, the predetermined current is that the operator inputs this current value. The surface treatment apparatus of the present invention (FIG. 1) also includes an input section for a predetermined current value.

Next, the object 11 after the MA-th step (step) is moved in the Z direction by a distance Δb. Thus, the object 11 is immersed in the electrolytic solution 22 up to the first processing section A and the second processing section B adjacent to the first processing section A. While maintaining this immersed state, a desired oxide film is formed in the second processing section B under the same conditions as the MA step (step) [FIG. 3D: MB step (step)].
At this time, an oxide film is hardly formed on the first processing section A. In FIG. 3D, the symbol Δb is the width of the second processing section B in the Z direction. In FIG. 3D, reference numeral 15b1 denotes an oxide film formed in the second processing section B.

  Next, the object 11 having undergone the MB step (step) is moved in the Z direction by a distance Δc. Thus, the object 11 is immersed in the electrolytic solution 22 up to the third processing section C adjacent to the second processing section B together with the first processing section A and the second processing section B. While maintaining this immersion state, a desired oxide film is formed in the third processing section C under the same conditions as in the MA step (step) [FIG. 3 (e): MC step (step)]. At that time, almost no oxide film is formed in the first processing section A and the second processing section B. In FIG. 3E, the symbol Δc is the width of the third processing section C in the Z direction. In FIG. 3E, reference numeral 15c1 denotes an oxide film formed in the third processing section C.

Similarly, after the third processing section C, the object to be processed 11 is moved by a predetermined distance in the Z direction, and is immersed in the electrolytic solution 22 up to the adjacent processing sections in order. While maintaining this immersion state, a desired oxide film is formed in the adjacent processing section under the same conditions as in the MA step (step).
In this manner, the steps (steps) similar to the MB step (step) and the MC step (step) are sequentially repeated until the last processing section N of the processing target 11 (that is, all the processing surfaces of the processing target 11). Is immersed in the electrolytic solution 22. While maintaining this immersed state, a desired oxide film is formed on the last processing section (the n-th processing section) N under the same conditions as the MA step (step) [FIG. 3 (f): MN step (step)] ]. At this time, almost no oxide film is formed in the processing section immediately before the first processing section A to the last processing section N. As a result, a state in which an oxide film is formed over the entire surface of the processing target surface of the processing target 11 is obtained. In FIG. 3F, the symbol Δn is the width of the last processing section N in the Z direction. In FIG. 3E, reference numeral 15n1 denotes an oxide film formed in the last processing section N.

Through the above first M step (a MA step (step) to the MN step (step)), a series of steps of forming an oxide film and held to a predetermined voltage V _M is completed. Thereafter, the processing target 11 on which the oxide film is formed is pulled up (moved in the −Z direction) from a state of being immersed in the electrolytic solution 22, so that the processing target 11 is exposed from the electrolytic solution 22.

Then, a higher than the predetermined voltage _{V M} the previously set voltage, holds the micro arc voltage lower than the maximum voltage _{V max} of oxidation _{V M + 1 (V M <} V M + 1 <V max), a predetermined current while managing so that I _1, to form the desired oxide film on the first processing compartment a of the object to be processed 11. Hereinafter, as in the case of the voltage VM described above, a series of steps (the MAth step (step) to the MNth step (step)) are performed. Thus, over the entire surface to be processed of the workpiece 11, obtained on the oxide film formed at a predetermined voltage V _M, the state in which the oxide film formed at a predetermined voltage V _{M + 1} is formed Can be

Said voltage _{V M} is increased in order in the direction of the highest voltage _{V max} is a predetermined numerical _{(V M <V M + 1} <V M + 2 <V M + 3 <·· <V M + n <V max), wherein the M step (a By repeatedly performing the MA process (step) to the MN-th process (step)), the oxide film having a desired total thickness is formed over the entire surface of the processing target surface of the processing target 11. Can be.

That is, the surface treatment method according to the present invention, the treated surface of the object to be processed is intermittent oxidation (maintained at a low voltage V _M than the maximum voltage V _max of the micro-arc oxidation process, a predetermined current I ₁ The above-mentioned M-th step is performed so as to be covered with the oxide film. Further, said voltage V _M is increased in order in the direction of the highest voltage V _max is a predetermined number, by repeating the first M step to form the oxide film total thickness is composed of desired thickness .

As described above, based on FIG. 3, in the anodic oxidation process, the number of the steps is “3 or more”, and the MA-th step (step), the MB-th step (step),. -Although the case where the above-mentioned MN process (step) immerses the object to be processed intermittently in the above-mentioned electrolytic solution was explained, the present invention is not limited to this.
The number of steps may be “1 or 2”. Further, the MA-th step (step), the MB-th step (step),..., The MN-th step (step) constituting the M-th step “intermittently” perform the electrolysis of the object to be processed. Instead of immersion in the solution, a method of immersing the object to be processed in the electrolyte solution “continuously” may be adopted.
That is, in the anodic oxidation process, the number of the steps is “1”, and the Mth step (step), the MBth step (step),... Step) may immerse the object to be processed “continuously” or “intermittently” in the electrolytic solution. At that time, the first MB step (step), the value of the predetermined current in ... the first MN step (step), are the same numerical value as the predetermined current I ₁ in the first MA step (step) Is preferred.

Hereinafter, when a control unit included in the integrated control device is employed, the MA step (step) of the M-th step (M is an integer of 2 or more), the MB step (step),. In the process (step), a typical correspondence of “target value, current value, operation amount, and movement amount” used to control “intermittently” when the object to be processed is immersed in the electrolyte solution State.
The target value is a predetermined current value input by the operator.
The current value is the processing current (current during anodic oxidation processing).
The manipulated variable is the speed at which the object is immersed. The immersion speed is typically a fixed speed input by the operator, but may be a speed obtained by multiplying the difference between the target value and the current value by a proportional constant. In the latter case, the surface treatment can be performed in a shorter time.

The moving amount is the moving distance of the object in the Z direction. The movement amount is taken into the control unit by a sensor (not shown) or the like. At this time, immersion to a certain processing section is synonymous with moving in the Z direction from the initial position until the movement amount corresponding to the next processing section is matched.
Alternatively, a value obtained by time-integrating the operation amount may be used as the movement amount, and the sensor may not be used, and the movement may be performed in the Z direction until the movement amount corresponds to the next processing section. Here, the definition of the movement amount corresponding to the processing section is an arbitrary value input by the operator, but it is desirable to set a value corresponding to the control cycle time of the control unit. This is because a minimum processing section can be realized by performing this setting.

The control unit detects that the immersion to a certain processing section is completed by comparing the “movement amount” with the “movement amount corresponding to the processing section”, and then detects the “target value” and the “current value”. Is compared. As a result of the comparison, if the current value is equal to or less than the predetermined current value, there is no need to stop, and the movement corresponding to the next processing section is permitted.
If the current value exceeds a predetermined value, the process of stopping the immersion, that is, the operation amount is set to zero. However, a slight movement of the workpiece in the reverse direction is acceptable within the adjustment range of the actual machine.
As described above, in the present invention, the control unit repeatedly executes this series of processes a plurality of times, so that the MA-th step (step), the MB-th step (step), ..., the MN-th step ( Step) is performed. In other words, depending on the result of comparing the target value with the current value, there may be cases where “intermittent processing”, “partial continuous processing”, or “all continuous processing” is performed. is there.

FIG. 2A is a flowchart illustrating the above-described surface treatment method according to the present invention, and illustrates that the M-th step (the MA-th step (step) to the MN-th step (step)) is repeatedly performed. FIG. 2B is a diagram schematically illustrating the positional relationship between the object 11 and the electrolytic solution 22 corresponding to FIGS. 3B and 3F.
That is, FIG. 2 (a), the relationship between the current value I and the predetermined current I ₁ during anodic oxidation treatment, if they meet the 'I ₁ ≧ I "represents that the process proceeds in the direction of YES.
Note that, even when “I ₁ ≧ I” is satisfied, the actuator position may be set to Z ₁ <Z. When this condition is satisfied, the “MAth process (step) to the MNth process (step)” constituting the Mth process are regarded as one continuous process without being classified. Here, Z ₁ is the front side surface position of the rear surface of the substrate in a state in contact with the liquid surface (height) of the substrate, Z is the position of the rear surface of the substrate during the anodization (height), represent each a [FIG. 2 (b)].

  Therefore, the present invention is to form an oxide film intermittently on an object to be processed having a large area by micro-arc oxidation, even with a power supply device having a small current density and a simple electrolyte cooling mechanism. To provide a possible surface treatment method.

Further, the surface to be treated of the object to be treated by the surface treatment method of the present invention is covered with a multilayer structure of an oxide film formed by intermittent oxidation treatment. Maintained at a low voltage V _M than the maximum voltage V _max during formation of the oxide film, by which a predetermined current I _1, even if the intermittent processing, it is never remain chromatic patterns on treated surface . Therefore, the present invention contributes to providing an oxide film having excellent uniformity of the appearance of the treated surface.

FIG. 4 is a graph showing the relationship between the voltage and current applied during the formation of the oxide film and the processing time, and is a voltage-current curve in the case of processing by the method of the present invention. In FIG. 4, the solid line represents the voltage, and the dotted line represents the current.
FIG. 4 shows that in the surface treatment method of the present invention, when the oxide film is formed, the voltage V _M is controlled to maintain a predetermined current I ₁ when the voltage V _M is lower than the maximum voltage V _max. . In the present invention also as shown in FIG. 4, said voltage _{V M} is increased in order in the direction of the highest voltage _{V max} predetermined value _{(V M <V M + 1} <V M + 2 <V M + 3 <·· <V M + n <and V _max), even when subjected to the first M step (a MA step (step) to the MN step (step)), and is controlled so as to maintain a predetermined current _{I 1.}

Furthermore, as shown in FIG. 4, following the end of the M step (a MA step (step) to the MN step (step)), than the last of the voltage V _M to the M step is performed A step P of performing the anodic oxidation process by continuously or intermittently dropping the voltage for a predetermined time to a low voltage _VM- , and a step Q of performing a constant voltage process at the voltage _VM- in order. It may be further provided.
Thus, without the latter voltage (V _M-) In breakdown, as higher the former voltage (V _M) in breakdown than the latter voltage (V _M-), fully repair the weak It is possible to obtain an oxide film having higher withstand voltage and corrosion resistance.
Such, by repeating several times the voltage variation between the former voltage (V _M) and the latter voltage (V _M-), it is preferable to carry out the repair of the membrane more securely.

FIG. 5 is a graph showing the relationship between the voltage and current applied during the formation of the oxide film and the processing time, and is a voltage-current curve in the case where the processing is performed collectively. In FIG. 5, a solid line represents a voltage, and a dotted line represents a current.
By comparing FIG. 4 and FIG. 5, when the batch processing is performed, the processing time is 1/3 of the processing time by the method of the present invention, but the processing current is three times that of the processing by the method of the present invention. It turns out that it is necessary. From this, it has been clarified that the continuous processing according to the present invention can suppress the processing current and can process a large-sized object with small equipment.

FIG. 6 is a graph showing the relationship between the position of the object to be processed in the immersion direction and the processing time.
FIG. 6 shows that when the processing voltage is low, the entire sample is immersed and the time until the processing at that voltage is completed is short. On the other hand, when the processing voltage is high, it can be seen that the entire sample is immersed and the time until the processing at that voltage is completed is long.

In the surface treatment method of the present invention, when the first treatment section, the second treatment section, and the n-th section in the object to be treated are sequentially immersed in the electrolytic solution, the depth of the electrolytic solution is Preferably, the position of the object with respect to the level of the electrolytic solution is controlled so that the object proceeds or stops in the direction.
Accordingly, it is possible to prevent an operation in which a region of the processing target surface of the processing target 11 where a film has not yet been formed enters or exits the liquid surface of the electrolytic solution 22. Therefore, it is possible to stably form the oxide film in a state where the phenomenon of dielectric breakdown hardly occurs.

As described above, as a method of controlling the position of the processing target 11 with respect to the liquid surface of the electrolytic solution 22, there are two methods described below.
A first method is a method of fixing the height position of the liquid surface of the electrolytic solution and adjusting the height position of the object to be processed with respect to the liquid surface of the electrolytic solution.
A second method is a method of fixing the height position of the object to be processed and adjusting the height of the liquid surface of the electrolytic solution with respect to the height position of the object to be processed.
In any of the methods, the position of the target object 11 with respect to the level of the electrolytic solution 22 can be controlled. When the object 11 is small (the processing area is small), any method may be selected. However, when the object to be processed 11 is large (the processing area is large), the electrolytic tank 21 for storing the electrolytic solution 22 also has a large capacity, so the first method is suitable.

As the surface treatment apparatus of the present invention, there is a surface treatment apparatus as shown in FIG. That is,
The surface treatment apparatus according to the present invention moves the object to be processed in the depth direction of the electrolytic solution in order to immerse the object to be processed to a specific treatment section in the electrolytic solution, and performs the specific treatment. There is provided a moving means of the object having a function of stopping the object at a position where the section is immersed in the electrolytic solution. Then, the moving unit applies a predetermined voltage over the entire area of the object to be processed, and every time a series of anodic oxidation processes is completed, the entire area of the object to be processed is exposed from the electrolytic solution. The anode means is configured to be moved to a position where the object is pulled up from the electrolyte.

Thus, according to the present invention, since it is possible to retain the current at the anode oxidation process comprising micro-arc oxidation process in a predetermined current I ₁ or less, large-capacity power supply is not required.
Furthermore, since the heat generation during the formation process of all oxide films can be positively reduced, the size of the system for cooling the processing system can be reduced as compared with the related art.
Therefore, the present invention provides an oxide film intermittently for an object to be processed having a large area by an anodic oxidation process including a micro-arc oxidation process, even with a small-current power supply device and a simple electrolytic solution cooling mechanism. To provide a surface treatment apparatus capable of forming a surface treatment device.
Further, since the surface treatment apparatus of the present invention is provided with the above-described anode means, an oxide film having a desired film thickness is formed on a large-sized workpiece so as to automatically cover the workpiece. it can.

The "current density" focused on in the present invention refers to the length around the surface of the object specified by the liquid level of the electrolytic solution in a state where the specific processing section of the object to be processed is immersed in the electrolytic solution. This is a numerical value obtained by dividing the current value by (perimeter), and is a so-called “line current density”.
In FIG. 3A, when the size of the object is x1 = 2500 mm, x2 = 3000 mm, and x3 = 50 mm, the length around the surface of the object (perimeter) is “2500 × 2 + 50 × 2”. ". When the (maximum) voltage applied from the (DC) power supply device is 50 V and the (maximum) current is 50 A, the “linear current density” is calculated as 0.0098 A / mm (≒ 50/5100). That is, only a very weak current acts on the periphery (peripheral portion) of the surface of the object to which the liquid surface of the electrolyte contacts. Therefore, according to the present invention, it is possible to stably form an oxide film in a state where the phenomenon of dielectric breakdown hardly occurs in a region other than the growth region of the oxide film.

According to the present invention, an oxide film can be formed only by such an extremely weak current. Therefore, according to the present invention, a power supply device for supplying a large current is not required, and a power supply device with a small current density can sufficiently form an oxide film. Therefore, the present invention provides a surface capable of forming an oxide film intermittently on an object to be processed having a large area by an anodic oxidation process including a micro-arc oxidation process, even with a simple electrolytic solution cooling mechanism. Bring processing equipment.
Further, since the surface treatment apparatus of the present invention includes the above-described anode means, it is possible to stabilize an oxide film having a desired film thickness so as to automatically cover a large-area object to be processed. To achieve the desired formation.

  INDUSTRIAL APPLICATION This invention is widely applicable to the surface treatment method of the to-be-processed object which consists of valve metals. INDUSTRIAL APPLICABILITY The present invention is suitably used as a surface treatment method for an article used in an internal space of a vacuum device, for example, a heater panel, a shower plate, and an inner wall material of a chamber.

11 Object to be processed, 21 Electrolyte tank, 22 Electrolyte, 22a Liquid level, 15a1, 15b1
, 15c1,... 15n1 (15) oxide film, A, B, C,.

Claims (3)

A surface treatment apparatus for performing an anodic oxidation process including a micro-arc oxidation process by immersing an object to be processed made of a valve metal in an electrolytic solution to form an oxide film on the object to be processed,
Anode means for forming the oxide film by the anodic oxidation treatment on the surface of the object to be processed,
An electrolyte bath containing the electrolyte, and having an opening that allows the anode means to be immersed in the electrolyte,
Cathode means arranged opposite to the anode means in the electrolytic solution,
In the state where the anode means and the cathode means are immersed in the electrolytic solution, a predetermined voltage is applied to generate a current I between the anode means and the cathode means to perform the anodic oxidation treatment. Power supply means,
The object to be processed is moved in the depth direction of the electrolytic solution in order to immerse the processing object in the electrolytic solution up to a specific processing section, and the specific processing section is immersed in the electrolytic solution. The object to be processed is provided with a function of stopping the object to be immersed at the position where the object is immersed. Movement in the depth direction of the electrolytic solution, moving means of the object to be processed,
A control device for controlling the power supply means and the moving means,
Including
The moving means applies a predetermined voltage over the entire area of the object to be processed, and every time a series of anodic oxidation processes is completed, from the electrolytic solution to a position where the entire area of the object to be processed is exposed. Is configured to move the anode means in a direction to pull up the object to be processed from the electrolytic solution ,
The control unit repeats performing an anodic oxidation process over the entire area of the object to be processed (M-th step) ;
A surface treatment apparatus characterized by the above-mentioned. The control device repeats an M-th process that is an anodic oxidation process over the entire area of the object to be processed,
Each time the first M step is anodized a predetermined voltage is applied to V _M is finished, in the next M th step, a function of applying a predetermined voltage higher than the voltage V _M to the workpiece Prepare,
The surface treatment apparatus according to claim 1, wherein: The controller compares the current value I and the predetermined current value I ₁ at the time of the anodic oxidation treatment,
When the relationship between the current value I during the anodic oxidation treatment and the predetermined current I ₁ satisfies “I ₁ ≧ I”, the object is moved in the depth direction of the electrolytic solution,
Current value I during the anodic oxidation treatment, if it exceeds the predetermined current value I ₁ is a function to quiesce the object to be processed,
The surface treatment apparatus according to claim 1 or 2, wherein:

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