JP2019039030A - Surface treatment method and surface treatment apparatus - Google Patents

Abstract

To provide a surface treatment method that can form an oxide film on a large-area to-be-treated object by an anode oxidation treatment including a micro-arc oxidation treatment even when a power supply with small current density and a simple cooling mechanism with electrolyte are used.SOLUTION: A plurality of processing sections A, B, C,...N are set in accordance with the processing frequency when the to-be-treated surface of a to-be-treated object 11 is processed by an oxidation treatment continuously or intermittently. In a Mth process (M is an integer of 2 or greater), a voltage Vis held lower than the maximum voltage Vprovided in an anode oxidation treatment including a micro-arc oxidation treatment so that an electric current is a predetermined current I, and the anode oxidation treatment is performed to the plurality of processing sections A, B, C,...N in order. The Mth process is repeatedly performed in such a manner that the voltage Vis increased toward the maximum voltage Vso as to be a predetermined value. As a result, the oxide film with a desired thickness in total is formed by a surface treatment method of the present invention.SELECTED DRAWING: Figure 3

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 surface to be processed 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 is known in which an oxide film is formed on the surface of a target object by performing an anodic oxidation process including a micro-arc oxidation process on a target object 111 having a small area. In FIG. 7, reference numeral 121 represents an electrolytic solution tank, and reference numeral 122 represents an electrolytic solution. When the object to be processed 111 has a small area, an oxide film may be formed by immersing the entire object to be processed 111 in the electrolytic solution 122. However, as the object to be processed 111 becomes a large area, in the method shown in FIG. 7, that is, in the anodic oxidation process including the micro arc oxidation process that requires high voltage and high current density, facilities such as a power source and a chiller are provided. Becomes large, and it becomes difficult to process a large-scale object to be processed.

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

  In order to solve the problem in the method of Patent Document 1, the present inventor has further proposed a method of performing surface treatment without using a mask (Patent Document 2). Thereby, the process of removing the mask material becomes unnecessary, and the work efficiency is improved. However, in the method disclosed in Patent Document 2, a striped pattern remains on the processing surface of the object to be processed, and an improvement in the appearance of the processing surface has been demanded.

In view of this, the present inventor has studied a method of performing micro-arc oxidation treatment on a workpiece of several m ² without dividing the surface of the workpiece having a large area. In the case of micro-arc oxidation treatment (anodic oxidation treatment with spark discharge), the treatment is performed at a higher current density and high voltage as compared with 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 micro arc oxidation treatment, a large-scale power supply facility, a large-scale electrolyte cooling mechanism, etc. are required, which is expensive in terms of facilities. 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 low-current power supply device and a simple electrolyte cooling mechanism, a large area is covered by anodic oxidation treatment including micro-arc oxidation treatment. It is an object to provide a surface treatment method and a surface treatment apparatus capable of intermittently forming an oxide film on a treatment body.

In order to solve the above problems, the present invention provides the following surface treatment method and surface treatment apparatus. That is,
The invention according to claim 1 sets a plurality of processing sections on the processing surface of the target object made of a valve metal, performs an anodic oxidation treatment by intermittently immersing each processing section in an electrolytic solution, A surface treatment method for forming an oxide film on the surface to be treated,
The anodizing treatment is composed of an Mth step (M is an integer of 2 or more),
The Mth step includes
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 that has finished the Ma process is immersed in the electrolytic solution up to a second process section adjacent to the first process section, and a desired oxide film is applied to the two process sections under the same conditions as in the Ma process. Forming the Mb step;
The object to be processed that has finished the Mb step is immersed in the electrolytic solution up to the nth processing section, and a desired oxide film is formed on the n processing section under the same conditions as in the Ma process. A Mn-th step (n is an integer of 1 or more) for forming an oxide film over the entire area,
The voltage of V _M 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 is characterized by that.

According to a second aspect of the present invention, in the first aspect, the anodic oxidation treatment is such that the n is 1, and the Mth step, the Ma step, the Mb step,. The Mn process is characterized in that the object to be treated is immersed in the electrolytic solution continuously or intermittently.
Invention according to claim 3, in claim 2, wherein said Mb step, the value of the predetermined current in ... the first Mn step, that is the same as the predetermined current I ₁ in the first Ma step Features.
According to a fourth aspect of the present invention, in the first aspect, when the first processing section, the second processing section, and the nth section of the object to be processed are sequentially immersed in the electrolytic solution, The position of the object to be processed with respect to the liquid surface of the electrolyte is controlled so that the object to be processed advances or stops in the depth direction of the electrolyte.
According to a fifth aspect of the present invention, in the fourth aspect, in order to control the position of the object to be processed with respect to the liquid surface of the electrolytic solution, a height position of the liquid surface of the electrolytic solution is fixed, and the electrolytic solution The height position of the object to be processed is adjusted with respect to the liquid level.
In order to control the position of the object to be processed with respect to the liquid surface of the electrolytic solution, the height of the object to be processed is fixed, and the invention described in claim 6 fixes the height of the object to be processed. The height of the electrolyte surface is adjusted with respect to the height position.
The invention according to claim 7, continuous claims following the end of the M step in claim 1, wherein the final low voltage V to _M- than the M step the voltage V _M made a predetermined time The method further includes a step P for performing the anodic oxidation treatment by dropping the voltage periodically or intermittently, and a step Q for performing the constant voltage treatment at the voltage _VM− .

The invention according to claim 8 is a surface treatment apparatus for performing an anodic oxidation treatment by immersing a workpiece made of a valve metal in an electrolytic solution, and forming an oxide film on the workpiece.
An anode means for forming the oxide film by anodic oxidation on the surface to be processed of the object to be processed;
An electrolytic bath containing the electrolytic solution and having an opening that allows the anode means to be immersed in the electrolytic solution;
Cathode means disposed opposite to the anode means in the electrolyte solution;
In the state where the anode means and the cathode means are immersed in the electrolytic solution, a power supply means for generating an electric current between the anode means and the cathode means to perform the anodization treatment;
In order to immerse the object to be treated up to a specific processing section in the electrolytic solution, the object to be processed is moved in the depth direction of the electrolytic solution, and up to the specific processing section is in the electrolytic solution. A moving means of the object to be processed having a function of stopping the object to be processed in an immersed position,
The moving means applies a predetermined voltage over the entire area of the object to be processed, and each time a series of anodic oxidation processes is completed, from the electrolyte solution to a position where the entire area of the object to be exposed is exposed. The anode means is configured to move 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 Mth step (M is an integer of 2 or more) 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, the oxide film final thickness consists of desired thickness Form. As a result, the present invention provides a power supply device with a small current density and a simple electrolytic solution 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 colored pattern does not remain on the processing surface. For this reason, it becomes possible to obtain an oxide film excellent in the homogeneity of the appearance of the treated surface.
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 Mn step, the Mth step, The object to be treated may be immersed in the electrolytic solution continuously or intermittently. 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 treated in the depth direction of the electrolytic solution in order to immerse the object to be treated up to a specific treatment section in the electrolytic solution. An object to be processed is provided with a function of stopping the object to be processed at a position where the section is immersed in the electrolytic solution. The moving means applies a predetermined voltage over the entire area of the object to be processed and exposes the entire area of the object to be processed from the electrolytic solution every time a series of anodic oxidation processes are completed. The anode means is moved to a position in a direction to pull up the object to be processed from the electrolytic solution. 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 actively reduced, the system for cooling the processing system can be made smaller than the conventional system.
Therefore, the present invention can form an oxide film intermittently on an object to be processed having a large area by micro arc oxidation treatment even with a power supply device with a small current density and a simple electrolyte cooling mechanism. Resulting in a surface treatment device capable of
In addition, since the surface treatment apparatus of the present invention includes the above-described anode means, an oxide film having a desired film thickness is formed on a large-area workpiece to automatically cover the workpiece. it can.

The block diagram which shows the surface treatment apparatus which concerns on this invention. The flowchart which shows the surface treatment method which concerns on this invention. Explanatory drawing which shows the surface treatment method which concerns on this invention. It is a graph which shows the relationship between voltage and electric current, and processing time, and is the voltage-current curve at the time of processing by the method of this invention. It is a graph which shows the relationship between a voltage and an electric current, and processing time, and is a voltage-current curve at the time of processing collectively. The batch treatment is a method in which the entire surface of the object to be treated (whole) is immersed in an electrolytic solution at the same time. The graph which shows the relationship between the position of to-be-processed object in the direction to immerse, and processing time. Explanatory drawing which shows the conventional surface treatment method.

  Hereinafter, the best mode of a surface treatment apparatus and a surface treatment method according to the present invention will be described with reference to the drawings. The present embodiment is specifically described for better understanding of the gist of the invention, and does not limit the present 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 is a surface on which an object to be treated 11 made of aluminum or an aluminum alloy is immersed in an electrolytic solution 22 for anodic oxidation to form an oxide film on the object to be treated. It is a processing device.
In this surface treatment apparatus, the object 11 on which an oxide film is formed by anodic oxidation functions as an anodic means.

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

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

  That is, the moving means 40 connects the first support part 41 that can be moved up and down, the other end of the first support part 41 and the upper end of the object to be processed 11, and hangs the object 11 to be processed. The 2nd support part 42 to keep is provided. As a result, the object 11 is subjected to a series of anodizing treatments by applying a predetermined voltage over the entire region (all areas in the direction (Z direction) in which the object 11 is immersed in the electrolytic solution 22). It can be performed. Further, each time the series of anodic oxidation processes is completed, the moving means 40 moves the object to be processed 11 from the electrolyte 22 to a position where the entire area of the object 11 is exposed from the electrolyte 22. The anode means (object 11) is configured to move.

  The vertical movement of the moving means 40 is controlled from the information processing device 60 via the sequencer 50. The information processing device 60 controls information (voltage, current) applied from the power supply means 30 to the anode means (object 11) and the cathode means 17 through the communication line. Although FIG. 1 shows a configuration example in which the sequencer 50 and the information processing device 60 are divided and arranged, a control device that integrates them may be used (not shown). The control unit included in the control device preferably includes a comparison unit having a function of comparing the predetermined current value and the processing current value.

FIG. 2 is a flowchart showing the surface treatment method according to the present invention. FIG. 3 is an explanatory view showing a surface treatment method according to the present invention. In the description based on FIG. 3 below, in the anodizing treatment, the nth is “3 or more” and the Mth step (M is an integer of 2 or more) constitutes the Mth step, the Mbth step. Steps: The case where the Mn 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 surface to be treated 11 of aluminum or an aluminum alloy [FIG. Anodizing treatment is performed by intermittently immersing in the electrolytic solution for each processing section, and an oxide film is formed on the surface to be processed. Here, “intermittent” means that the processing section A is first, then the processing section B, then the processing section C, and finally the processing section N (that is, the object 11 to be processed). The entire surface to be treated) is immersed in an electrolyte solution in order, and the anodic oxidation treatment is performed.
In FIG. 3A, x1 represents the width of the object 11 to be processed, x2 represents the height of the object 11 to be processed, and x3 represents the thickness of the object 11 to be processed.

The anodic oxidation treatment in the surface treatment method of the present invention comprises the Mth step (M is an integer of 2 or more) described later. That is,
The M-th (M is an integer of 2 or more) process includes a Ma process, an Mb process, an Mc process,.

In the Ma step, the workpiece 11 is moved in the Z direction by a distance Δa. Thereby, only the 1st process division A among the to-be-processed bodies 11 is made into the state immersed in the electrolyte solution 22. As shown in FIG. 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 the section A [FIG. 3 (b) → FIG. 3 (c): Step Ma]. In FIG. 3B and FIG. 3C, 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 one in which the operator inputs this current value. The surface treatment apparatus (FIG. 1) of the present invention also includes an input unit for a predetermined current value.

  Next, the workpiece 11 that has finished the Ma process is moved by a distance Δb in the Z direction. Thereby, let the to-be-processed object 11 be the state immersed in the electrolyte solution 22 to the 2nd process area B adjacent to this 1st process area A with the 1st process area A. While maintaining this immersed state, a desired oxide film is formed in the second processing section B under the same conditions as in the Ma process [FIG. 3 (d): Mb process]. At that time, almost no oxide film is formed in 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 is an oxide film formed in the second processing section B.

  Next, the workpiece 11 that has completed the Mb step is moved by a distance Δc in the Z direction. Thereby, let the to-be-processed object 11 be the state immersed in the electrolyte solution 22 to the 3rd process area C adjacent to this 2nd process area B with the 1st process area A and the 2nd process area B. While maintaining this immersed state, a desired oxide film is formed in the third treatment section C under the same conditions as in the Ma process [FIG. 3 (e): Mc process]. 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. 3 (e), reference numeral 15 c 1 is an oxide film formed in the third processing section C.

Similarly, after the third processing section C, the workpiece 11 is moved by a predetermined distance in the Z direction, and is sequentially immersed in the electrolytic solution 22 to the adjacent processing sections. While maintaining this immersed state, a desired oxide film is formed in the adjacent processing section under the same conditions as in the Ma step.
Thus, the process similar to Mb process and Mc process is repeated in order, and the state which was immersed in the electrolyte solution 22 (namely, all the to-be-processed surfaces of the to-be-processed object 11) was immersed to the last process division N of the to-be-processed object 11. And While maintaining this soaked state, a desired oxide film is formed in the last processing section N under the same conditions as in the Ma process [FIG. 3 (f): Mn process]. At that time, almost no oxide film is formed in the processing section immediately before the first processing section A to the last processing section N. Thereby, the state by which the oxide film was formed over the whole to-be-processed surface of the to-be-processed object 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, second Mn step), a series of steps of forming an oxide film and held to a predetermined voltage V _M is completed. Thereafter, the object 11 on which the oxide film is formed is pulled up (moved in the −Z direction) from the state where it is immersed in the electrolyte 22, and the object 11 is exposed from the electrolyte 22.

Then, it is maintained at a voltage V _{M + 1} (V _M <V _{M + 1} <V _max ) that is higher than the predetermined voltage V _M set earlier and lower than the maximum voltage V _max of the micro arc oxidation treatment, and 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, similarly to the case of the voltage V _M as described above, a series of steps (a Ma step, second Mn step). 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 It is done.

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 to Mn-th process), the oxide film having a desired total thickness can be formed over the entire surface of the object 11 to be processed.

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-described Mth 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 n is “3 or more”, and the M-th process, the M-th process, the M-b process,. Although the case where the object to be processed is “intermittently” immersed in the electrolytic solution has been described, the present invention is not limited to this.
The n may be “1 or 2”. In addition, the Ma process, the Mb process,... The Mn process, which constitute the M process, are not intermittently immersed in the electrolytic solution. You may employ | adopt the method of immersing a process body in the said electrolyte solution "continuously".
That is, in the anodic oxidation process, the n is “1”, and the Mth process, the Mb process,... The Mn process constitute the Mth process. It is also possible to immerse in the electrolyte solution in a “target” or “intermittent” manner. At that time, the second Mb step, the value of the predetermined current in ... the first Mn step is preferably set to the same numerical value as the predetermined current I ₁ in the first Ma step.

Hereinafter, in the case where the control unit included in the integrated control device is employed, in the Mth step (M is an integer of 2 or more), the Mth step, the Mb step,. A typical correspondence of “target value, current value, operation amount, movement amount” used for “intermittent” control when the body is immersed in the electrolytic solution will be described.
The target value is a predetermined current value input by the operator.
The current value is the processing current (current during anodic oxidation).
The operation amount is the speed at which the workpiece is immersed. This 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 movement amount is the movement distance of the workpiece in the Z direction. The movement amount is taken into the control unit by a sensor or the like (not shown). At this time, the 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 reached.
Alternatively, a value obtained by integrating the operation amount over time may be used as the movement amount, and the sensor may not be necessary, and the movement amount may be moved in the Z direction until it matches the movement amount corresponding 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 the 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 “target value” and “current value”. Make a comparison. As a result of this comparison, if it is equal to or less than a predetermined current value, it is not necessary to stop, so movement corresponding to the next processing section is permitted.
In addition, when exceeding a predetermined electric current value, the process which stops immersion, ie, an operation amount, is made into 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 performs the processes of the Ma process, the Mb process,. In other words, depending on the result of comparing the target value with the current value, it may be “intermittent processing”, “partly continuous processing”, or “all continuous processing”. is there.

FIG. 2A is a flowchart showing the surface treatment method according to the present invention described above, and represents that the Mth step (Math to Mnth steps) is repeated. FIG. 2B is a diagram schematically showing the positional relationship between the object to be processed 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.
Even when “I ₁ ≧ I” is satisfied, the actuator position may be Z ₁ <Z. When this condition is satisfied, the “Mth process to Mn process” constituting the Mth process is regarded as one continuous process without being divided. Here, Z ₁ represents the position (height) of the rear side surface of the substrate when the front side surface of the substrate is in contact with the liquid surface, and Z represents the position (height) of the rear side surface of the substrate during the anodic oxidation treatment. [FIG. 2 (b)].

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

In addition, the surface to be processed of the object to be processed by the surface treatment method of the present invention is covered with a multilayer structure of oxide films 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 . For this reason, this invention contributes to provision of the oxide film excellent in the homogeneity of the external appearance of the processing surface.

FIG. 4 is a graph showing the relationship between the voltage and current applied during the formation of the oxide film and the treatment time, and is a voltage-current curve when the treatment is performed by the method of the present invention. In FIG. 4, the solid line represents the voltage, and the dotted line represents the current.
From FIG. 4, in the surface treatment method of the present invention, when held at a low voltage V _M than the maximum voltage V _max during formation of the oxide film, it can be seen that are controlled so as to maintain a predetermined current I ₁ . 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, second Mn 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, second Mn step), a low voltage V to _M- than the last of the voltage V _M to the M step is performed A step P for performing the anodic oxidation treatment by continuously or intermittently dropping the voltage at a predetermined time and a step Q for carrying out the constant voltage treatment at the voltage V _M− 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 becomes possible to obtain an oxide film having higher withstand voltage and corrosion resistance.
It is preferable to repair the film more reliably by repeating such a voltage change between the former voltage (V _M ) and the latter voltage (V _M− ) a plurality of times.

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

FIG. 6 is a graph showing the relationship between the position of the object to be treated and the treatment time in the immersion direction.
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 treatment voltage is high, it can be seen that the entire sample is immersed and the time until the treatment 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 immersed in the electrolyte solution in order, the depth of the electrolyte solution It is preferable to control the position of the object to be processed with respect to the liquid surface of the electrolytic solution so that the object to be processed advances or stops in the direction.
Thereby, the operation | movement where the area | region in which the film | membrane is not yet formed among the to-be-processed surfaces of the to-be-processed object 11 comes in and out with respect to the liquid level of the electrolyte solution 22 can be prevented. Therefore, it is possible to stably form the oxide film in a state where the phenomenon of dielectric breakdown is unlikely to occur.

As described above, as a method for controlling the position of the workpiece 11 with respect to the liquid surface of the electrolytic solution 22, there are two methods described below.
The 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.
The second method is a method of fixing the height position of the object to be processed and adjusting the height of the electrolytic solution with respect to the height position of the object to be processed.
In any method, the position of the workpiece 11 with respect to the liquid surface 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 11 is large (the processing area is wide), the electrolytic cell 21 for storing the electrolytic solution 22 also has a large capacity, and therefore the first method is suitable.

An example of the surface treatment apparatus of the present invention 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 treated in the depth direction of the electrolytic solution in order to immerse the object to be treated up to a specific treatment section in the electrolytic solution. An object to be processed is provided with a function of stopping the object to be processed at a position where the section is immersed in the electrolytic solution. The moving means applies a predetermined voltage over the entire area of the object to be processed and exposes the entire area of the object to be processed from the electrolytic solution every time a series of anodic oxidation processes are completed. The anode means is moved to a position in a direction to pull up the object to be processed from the electrolytic solution.

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 actively reduced, the system for cooling the processing system can be made smaller than the conventional system.
Therefore, the present invention provides an oxide film that is intermittently applied to an object to be processed on a large area by an anodic oxidation treatment including a micro arc oxidation treatment, even with a small current power supply device and a simple electrolyte cooling mechanism. A surface treatment apparatus capable of forming the surface.
In addition, since the surface treatment apparatus of the present invention includes the above-described anode means, an oxide film having a desired film thickness is formed on a large-area workpiece to automatically cover the workpiece. it can.

The “current density” focused on in the present invention is the length around the surface of the target object specified by the liquid level of the electrolytic solution in a state where up to a specific processing section of the target object is immersed in the electrolytic solution. It is a numerical value obtained by dividing the current value by (circumference length), which is a so-called “linear current density”.
In FIG. 3A, when the size of the object to be processed is x1 = 2500 mm, x2 = 3000 mm, and x3 = 50 mm, the length (periphery) around the surface of the object to be processed 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, a very weak current only acts on the periphery (circumferential portion) of the surface of the workpiece to be in contact with the liquid surface of the electrolytic solution. Therefore, according to the present invention, it is possible to stably form the oxide film in a state where the dielectric breakdown phenomenon is unlikely to occur except in the growth region of the oxide film.

In the present invention, an oxide film can be formed only by the action of such a very weak current. Therefore, according to the present invention, there is no need for a power supply device that supplies a large current, and it is possible to sufficiently form an oxide film even with a power supply device with a low current density. Therefore, the present invention provides a surface capable of intermittently forming an oxide film on a workpiece having a large area by an anodic oxidation treatment including a micro-arc oxidation treatment even with a simple electrolyte cooling mechanism. Provide a processing device.
In addition, 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 the workpiece with respect to the workpiece having a large area. To achieve the formation.

  The present invention can be widely applied to a surface treatment method of an object to be processed made of a valve metal. The present invention is suitably used as a surface treatment method for articles used in the internal space of a vacuum apparatus, such as a heater panel, a shower plate, and an inner wall material of a chamber.

  DESCRIPTION OF SYMBOLS 11 To-be-processed object, 21 Electrolyte tank, 22 Electrolyte, 22a Liquid surface, 15a1, 15b1, 15c1, ... 15n1 (15) Oxide film, A, B, C, ... N Processing division.

In order to solve the above problems, the present invention provides the following surface treatment method and surface treatment apparatus. That is,
The invention according to claim 1 sets a plurality of processing sections on the processing surface of the target object made of a valve metal, performs an anodic oxidation treatment by intermittently immersing each processing section in an electrolytic solution, A surface treatment method for forming an oxide film on the surface to be treated,
The anodizing treatment is composed of an Mth step (M is an integer of 2 or more),
The Mth step includes
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 that has finished the Ma process is immersed in the electrolytic solution up to a second process section adjacent to the first process section, and a desired oxide film is formed on the second process section under the same conditions as in the Ma process. The Mb step of forming
The object to be processed after the Mb step is immersed in the electrolytic solution up to the nth processing section, and a desired oxide film is formed on the nth processing section under the same conditions as in the Ma process, and the surface to be processed Mn step (n is an integer of 1 or more) for forming an oxide film over the entire area of
The voltage of V _M 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 is characterized by that.

According to a second aspect of the present invention, in the first aspect, the anodic oxidation treatment is such that the n is 1, and the Mth step, the Ma step, the Mb step,. The Mn process is characterized in that the object to be treated is immersed in the electrolytic solution continuously or intermittently.
Invention according to claim 3, in claim 2, wherein said Mb step, the value of the predetermined current in ... the first Mn step, that is the same as the predetermined current I ₁ in the first Ma step Features.
The invention according to claim 4 is the invention according to claim 1, wherein the first processing section, the second processing section, and the n-th processing section in the object to be processed are sequentially immersed in the electrolytic solution. The position of the object to be processed relative to the liquid surface of the electrolyte is controlled so that the object to be processed advances or stops in the depth direction of the electrolyte.
According to a fifth aspect of the present invention, in the fourth aspect, in order to control the position of the object to be processed with respect to the liquid surface of the electrolytic solution, a height position of the liquid surface of the electrolytic solution is fixed, and the electrolytic solution The height position of the object to be processed is adjusted with respect to the liquid level.
In order to control the position of the object to be processed with respect to the liquid surface of the electrolytic solution, the height of the object to be processed is fixed, and the invention described in claim 6 fixes the height of the object to be processed. The height of the electrolyte surface is adjusted with respect to the height position.
According to a seventh aspect of the present invention, in the first aspect , the voltage VM− is lower than the voltage VM at which the last Mth step is performed, to a voltage VM− lower than the voltage VM− at which the last Mth step is performed. The method further comprises a step P of performing the anodic oxidation process by dropping the voltage continuously or intermittently in a period of time and a step Q of performing the constant voltage process at the voltage VM−.

The invention according to claim 8 is a surface treatment apparatus for performing an anodic oxidation treatment by immersing a workpiece made of a valve metal in an electrolytic solution, and forming an oxide film on the workpiece.
An anode means for forming the oxide film by anodic oxidation on the surface to be processed of the object to be processed;
An electrolytic bath containing the electrolytic solution and having an opening that allows the anode means to be immersed in the electrolytic solution;
Cathode means disposed opposite to the anode means in the electrolyte solution;
In the state where the anode means and the cathode means are immersed in the electrolytic solution, a power supply means for generating an electric current between the anode means and the cathode means to perform the anodization treatment;
In order to immerse the object to be treated up to a specific processing section in the electrolytic solution, the object to be processed is moved in the depth direction of the electrolytic solution, and up to the specific processing section is in the electrolytic solution. A moving means of the object to be processed having a function of stopping the object to be processed in an immersed position,
The moving means applies a predetermined voltage over the entire area of the object to be processed, and each time a series of anodic oxidation processes is completed, from the electrolyte solution to a position where the entire area of the object to be exposed is exposed. The anode means is configured to move in a direction in which the object to be processed is pulled up from the electrolytic solution.
The invention according to claim 9 is a surface treatment apparatus for performing an anodic oxidation treatment by immersing a target object made of a valve metal in an electrolytic solution, and forming an oxide film on the target object.
An anode means for forming the oxide film by anodic oxidation on the surface to be processed of the object to be processed;
An electrolytic bath containing the electrolytic solution and having an opening that allows the anode means to be immersed in the electrolytic solution;
Cathode means disposed opposite to the anode means in the electrolyte solution;
In the state where the anode means and the cathode means are immersed in the electrolytic solution, a power supply means for generating an electric current between the anode means and the cathode means to perform the anodization treatment;
In order to immerse the object to be processed up to a specific processing section in the electrolytic solution, the object to be processed is moved in the depth direction of the electrolytic solution, and a predetermined current value is compared with a value of the processing current. And, when the predetermined current value is exceeded, includes a means for moving the object to be processed having a function of stopping the object to be processed,
The moving means applies a predetermined voltage over the entire area of the object to be processed, and each time a series of anodizing treatment steps is completed, the position where the entire area of the object to be processed is exposed from the electrolytic solution. The anode means is moved in the direction of pulling up the object to be processed from the electrolytic solution, and in a series of anodizing treatment steps subsequent to the series of anodizing treatment steps, the predetermined voltage is applied. A high voltage is applied to the object as a predetermined voltage,
It is characterized by that.

Claims (8)

A plurality of processing sections are set on the processing surface of the target object made of valve metal, and each processing section is immersed in an electrolytic solution continuously or intermittently for anodic oxidation, and the processing surface is oxidized. A surface treatment method for forming a film,
The anodizing treatment is composed of an Mth step (M is an integer of 2 or more),
The Mth step includes
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 that has finished the Ma process is immersed in the electrolytic solution up to a second process section adjacent to the first process section, and a desired oxide film is applied to the two process sections under the same conditions as in the Ma process. Forming the Mb step;
The object to be processed that has finished the Mb step is immersed in the electrolytic solution up to the nth processing section, and a desired oxide film is formed on the n processing section under the same conditions as in the Ma process. A Mn-th step (n is an integer of 1 or more) for forming an oxide film over the entire area,
The voltage of V _M 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,
A surface treatment method characterized by the above. In the anodic oxidation treatment, the n is 1, and the M-th step, the M-th step, the Mb-step,. Dipping in the electrolyte solution,
The surface treatment method according to claim 1. 3. The surface treatment method according to claim 2, wherein a value of a predetermined current in the Mb step,..., The Mn step is the same as a predetermined current I ₁ in the Ma step. 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 object to be processed advances in the depth direction of the electrolytic solution. Or controlling the position of the object to be processed with respect to the liquid level of the electrolytic solution so as to stop,
The surface treatment method according to claim 1. In order to control the position of the object to be processed with respect to the liquid surface of the electrolytic solution, the height position of the liquid surface of the electrolytic solution is fixed, and the height position of the object to be processed with respect to the liquid surface of the electrolytic solution Adjust the
The surface treatment method according to claim 4. In order to control the position of the object to be processed with respect to the liquid level of the electrolytic solution, the height position of the object to be processed is fixed, and the height of the liquid surface of the electrolytic solution with respect to the height position of the object to be processed is fixed. Adjust the height,
The surface treatment method according to claim 4. Following the last Mth step in claim 1,
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,
Step Q for performing constant voltage processing at the voltage V _M− is further provided in order.
A surface treatment method characterized by the above. A surface treatment apparatus for performing an anodic oxidation treatment by immersing an object to be treated made of a valve metal in an electrolytic solution, and forming an oxide film on the object to be treated,
An anode means for forming the oxide film by anodic oxidation on the surface to be processed of the object to be processed;
An electrolytic bath containing the electrolytic solution and having an opening that allows the anode means to be immersed in the electrolytic solution;
Cathode means disposed opposite to the anode means in the electrolyte solution;
In the state where the anode means and the cathode means are immersed in the electrolytic solution, a power supply means for generating an electric current between the anode means and the cathode means to perform the anodization treatment;
In order to immerse the object to be treated up to a specific processing section in the electrolytic solution, the object to be processed is moved in the depth direction of the electrolytic solution, and up to the specific processing section is in the electrolytic solution. A moving means of the object to be processed having a function of stopping the object to be processed in an immersed position,
The moving means applies a predetermined voltage over the entire area of the object to be processed, and each time a series of anodic oxidation processes is completed, from the electrolyte solution to a position where the entire area of the object to be exposed is exposed. The surface treatment apparatus is configured to move the anode means in a direction in which the object to be treated is pulled up from the electrolytic solution.

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