DETECTION DEVICE AND METHOD OF ANODIC OXIDE FILM
A device for detecting an anodic oxide film during an anodic oxidation treatment includes a container receiving an electrolyte therein, an aluminum sheet immersed in the electrolyte, a power source supplying a current to the aluminum sheet to form an anodic oxide film on the aluminum sheet, a data acquisition unit measuring a potential of the anodic oxide film at a time, a data processor unit calculating a differential value of the potential, and a display unit displaying a differential curve generated according to the differential values of the potentials at different times. The quality of the anodic oxide film can be judged by reading the shape of the differential curve.
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1. Field of the Disclosure
The disclosure generally relates to detection devices and detection methods, and more particularly to a detection device and method for detecting an anodic oxide film during an anodic oxidation treatment.
2. Description of Related Art
Anodic oxide films have drawn much attention for industrial and nanotechnology uses because of their unique pore formation capability, which not only increases corrosion resistance but has the added value of enhanced cosmetic appearance. The anodic oxide film is composed of a porous layer. During an anodic oxidation treatment, a current density, a bath temperature, and an acid concentration of an electrolyte may influence a pore formation capability of the anodic oxide film. For example, a burnt film may be formed at a higher current density, and pitting and burning tend to occur at a lower acid concentration or when a concentration of a sulfate increases. However, to examine the texture of the anodic oxide film always involves the use of an electronic microscope and preparation of specimens, which is tedious and laborious.
For the foregoing reasons, there is a need in the art for a detection device and method for detecting an anodic oxide film which overcome the limitations described.
SUMMARYAccording to the disclosure, a device for detecting an anodic oxide film during an anodic oxidation treatment includes a container receiving an electrolyte therein, an aluminum sheet immersed in the electrolyte, a power source electrically connected to the aluminum sheet for supplying a current to the aluminum sheet to cause an anodic oxide film to grow on the aluminum sheet, a data acquisition unit measuring a potential of the anodic oxide film, a data processor unit calculating a first-order differential value of the potential at a time, and a display unit displaying a first-order differential curve generated according to the differential values of the potentials at different times. During a period between the time when the potential of the anodic oxide film reaches a maximum and the time when the potential of the anodic oxide film starts to become constant, if only one valley is formed on the first-order differential curve, the anodic oxide film is excellent; should there be more than one valleys formed on the first-order differential curve, the anodic oxide film has a poor quality.
Other advantages and novel features of the disclosure will be drawn from the following detailed description of the exemplary embodiments of the disclosure with attached drawings.
Referring to
An electrolyte 6, such as a solution including sulfuric acid, phosphoric acid, chromic acid, and organic acid, is filled in the container 14. The container 14 is received in a constant temperature device 7 to maintain a constant anodizing temperature during the anodic oxidation treatment. An aluminum sheet 9 functions as an anode and has a bottom end extending into the electrolyte 6 and a top end electronically connected to a positive pole 2 of the power source 1. An aluminum post 4 functions as a cathode and has a bottom end extending into the electrolyte 6 and a top end electronically connected to a negative pole 3 of the power source 1. Thus the power source 1 can supply a current to the aluminum sheet 9. The power source 1 can be adjusted to change a current density flowing through the aluminum sheet 9. A calomel electrode 5 is utilized as a reference electrode. The calomel electrode 5 has a bottom end extending into the electrolyte 6, and a top end connected to a reference terminal 82 of the data acquisition unit 8. An input terminal 81 of the data acquisition unit 8 is connected to the top end of the aluminum sheet 9, an earth terminal 83 of the data acquisition unit 8 is connected to the ground, and an output terminal 84 of the data acquisition unit 8 is connected to an input terminal 13 of the data processor unit 10. The display unit 11 is connected to an output terminal 12 of the data processor unit 10.
During the anodic oxidation treatment, the power source 1 supplies the current to the aluminum sheet 9 to cause an anodic oxide film to continuously grow on the aluminum sheet 9 until reaching a quasi-steady state. A pore formation capability of the anodic oxide film can be detected during the anodic oxidation treatment according to a detecting method shown in
In one specific anodic oxidation treatment, the electrolyte 6 is a sulfuric acid solution with a concentration of 15 wt %. The aluminum sheet 9 is anodized in the sulfuric acid solution at a bath temperature of 293K and a current density of 15 mA/cm2. The data acquisition unit 8 measures the potential U of the anodic oxide film at a frequency f of 100 Hz. The potential U of the anodic oxide film is converted to digital signal and sent to the data processor unit 10. The data processor unit 10 records the potential U of the anodic oxide film at the anodizing time t as U(t). Accordingly, the potential U of the anodic oxide film at the anodizing time t−1 is recorded as U(t−1), and the potential U of the anodic oxide film at the anodizing time t+1 is recorded as U(t+1). Then the data processor unit 10 calculates the first-order differential value U′ of the potential U according to a formula of U′=[U(t)−U(t−1)]*f. Thus a potential-time curve 20 is obtained according to the potentials U of the anodic oxide film at the anodizing times t, and a first-order differential curve 21 is obtained according to the first-order differential values U′ at the anodizing times t. Finally both of the potential-time curve 20 and the first-order differential curve 21 are displayed on the display unit 11, as shown in
The potential-time curve 20 and the first-order differential curve 21 can be divided into four segments, which correspond to four stages of the growth of the anodic oxide film, i.e., a barrier layer formation stage, a nanopore initiation and growth stage, a pore widening stage, and a quasi-steady state stage. The four stages are divided by three anodizing times, tU′max, tUmax, and tUconst. The anodizing time tU′max is the time that the first-order differential curve 21 has a maximum value: U′max. The anodizing time tUmax is the time that the potential-time curve 20 has a maximum value: Umax, and at this time, the first-order differential value U′ of the potential U is zero. The anodizing time tconst is the time that the first-order differential curve 21 and the potential-time curve 20 start to become straight and horizontal. In other words, from the anodizing time tconst, the potential U of the anodic oxide film is constant, the first-order differential value U′ of the potential U is zero. The barrier layer formation stage is from the start of formation of the anodic oxide film (i.e., t=0) to the anodizing time tU′max. The nanopore initiation and growth stage is from tU′max to tUmax. The pore widening stage is from tUmax to tUconst. After the anodizing time tUconst is the quasi-steady state stage. The pore formation capability of the anodic oxide film is judged according to an amount of valleys of the first-order differential curve 21 in the pore widening stage. If the first-order differential curve 21 has only one valley in the pore widening stage, the anodic oxide film formed on the aluminum sheet 9 is excellent. In contrast, if the first-order differential curve 21 has more than one valleys in the pore widening stage, the quality of the anodic oxide film is poor.
Referring to
In the nanopore initiation and growth stage, the potential U of the anodic oxide film continues to rise until reaching the maximum Umax. However, the increasing rate of the potential U of the anodic oxide film in the nanopore initiation and growth stage is slower. As shown in
In the pore widening stage, the anodic oxide film continues to growth until it reaches the quasi-steady state at the anodizing time tUconst. The pores of the anodic oxide film widen persistently and become apparent. According to the first-order differential curve 21 and the potential-time curve 20 of
In the pore widening stage, the potential-time curve 20 declines, and the potential U of the anodic oxide film decreases gradually form Umax to Uconst. The first-order differential curve 21 goes from zero to a minimum, and then lifts to zero again when the potential U of the anodic oxide film reaches Uconst. One valley is formed in the pore widening stage of the first-order differential curve 21 when the first-order differential value U′ of the potential U reaches the minimum U′min, which is indicated by point D. The time t and the minimum U′min at the point D are about 10.27s and −1.71. According to the yardstick, if the first-order differential curve 21 has only one valley in the pore widening stage, the anodic oxide film formed in this specific anodic oxidation treatment that the aluminum sheet 9 is anodized in a sulfuric acid solution of 15 wt % concentration at a bath temperature of 293K and a current density of 15 mA/cm2 has a good quality.
It is to be understood, however, that even though numerous characteristics and advantages of the disclosure have been set forth in the foregoing description, together with details of the structure and function of the disclosure, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the disclosure to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.
Claims
1. A method for detecting an anodic oxide film during an anodic oxidation treatment, comprising steps of:
- acquiring potentials of the anodic oxide film at different anodizing times by a data acquisition unit;
- calculating differential values of the potentials at the different anodizing times by a data processor unit;
- generating a differential curve according to the differential values of the potentials and displaying the differential curve on the display unit; and
- judging a pore formation capability of the anodic oxide film according to a shape of the differential curve.
2. The method of claim 1, further comprising generating a potential-time curve according to the potentials of the anodic oxide film at the different anodizing times, and displaying the potential-time curve associated with the differential curve on the display unit.
3. The method of claim 2, wherein during a period of the anodizing times from a time when a corresponding potential of the anodic oxide film reaches a maximum to a time when a corresponding potential of the anodic oxide film starts to become constant, if only one valley is formed on the differential curve, the anodic oxide film is excellent, and if more than one valleys are formed on the differential curve, the anodic oxide film is bad.
4. A device for detecting an anodic oxide film during an anodic oxidation treatment, comprising:
- a container receiving an electrolyte therein;
- an aluminum article extending into the electrolyte;
- a power source electrically connected to the aluminum article for supplying a current to the aluminum article to cause an anodic oxide film to grow on the aluminum article;
- a data acquisition unit measuring potentials of the anodic oxide film at different times;
- a data processor unit calculating differential values of the potentials at the different times; and
- a display unit displaying a differential curve generated according to the differential vales of the potentials.
5. The device of claim 4, wherein the container is received in a constant temperature device for maintaining a constant anodizing temperature during the anodic oxidation treatment.
6. The device of claim 4, wherein the power source can be adjusted to change a current density through the aluminum article.
7. The device of claim 4, wherein the aluminum article is connected to a positive pole of the power source, the device further comprising another aluminum article connected to a negative pole of the power source, and a calomel electrode function as a reference electrode.
8. The device of claim 7, wherein the calomel electrode has one end extending into the electrolyte, and another end connected to a reference terminal of the data acquisition unit, an input terminal of the data acquisition unit being connected to the aluminum article, and an output terminal being connected to the data processor unit.
9. The device of claim 7, wherein the data processor unit generates a potential-time curve according to the potentials of the anodic oxide film at the different times, and the display unit displays the potential-time curve associated with the differential curve.
10. The device of claim 4, wherein the electrolyte is a solution including one of sulfuric acid, phosphoric acid, chromic acid, and organic acid.
Type: Application
Filed: Nov 27, 2008
Publication Date: Oct 8, 2009
Applicant: FOXCONN TECHNOLOGY CO., LTD. (Tu-Cheng)
Inventors: PAI-SHENG WEI (Tu-Cheng), CHIA-SHOU CHANG (Tu-Cheng)
Application Number: 12/324,849
International Classification: C25D 21/12 (20060101); C25D 17/00 (20060101);