U.S. patent application number 12/324849 was filed with the patent office on 2009-10-08 for detection device and method of anodic oxide film.
This patent application is currently assigned to FOXCONN TECHNOLOGY CO., LTD.. Invention is credited to CHIA-SHOU CHANG, PAI-SHENG WEI.
Application Number | 20090250350 12/324849 |
Document ID | / |
Family ID | 41132258 |
Filed Date | 2009-10-08 |
United States Patent
Application |
20090250350 |
Kind Code |
A1 |
WEI; PAI-SHENG ; et
al. |
October 8, 2009 |
DETECTION DEVICE AND METHOD OF ANODIC OXIDE FILM
Abstract
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.
Inventors: |
WEI; PAI-SHENG; (Tu-Cheng,
TW) ; CHANG; CHIA-SHOU; (Tu-Cheng, TW) |
Correspondence
Address: |
PCE INDUSTRY, INC.;ATT. Steven Reiss
288 SOUTH MAYO AVENUE
CITY OF INDUSTRY
CA
91789
US
|
Assignee: |
FOXCONN TECHNOLOGY CO.,
LTD.
Tu-Cheng
TW
|
Family ID: |
41132258 |
Appl. No.: |
12/324849 |
Filed: |
November 27, 2008 |
Current U.S.
Class: |
205/81 ;
204/406 |
Current CPC
Class: |
G01N 27/48 20130101 |
Class at
Publication: |
205/81 ;
204/406 |
International
Class: |
C25D 21/12 20060101
C25D021/12; C25D 17/00 20060101 C25D017/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 3, 2008 |
CN |
200810066502.9 |
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.
Description
BACKGROUND
[0001] 1. Field of the Disclosure
[0002] 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.
[0003] 2. Description of Related Art
[0004] 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.
[0005] 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.
SUMMARY
[0006] According 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.
[0007] 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.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a diagrammatic view of a detection device
according to an exemplary embodiment for detecting an anodic oxide
film during an anodic oxidation treatment.
[0009] FIG. 2 is a flowchart of a detection method for detecting
the anodic oxide film during the anodic oxidation treatment using
the detecting device of FIG. 1.
[0010] FIG. 3 is a potential-time curve and an associated
first-order differential curve of the anodic oxide film formed by
anodizing an aluminum sheet in a sulfuric acid solution with a
concentration of 15 wt % at a bath temperature of 293K and a
current density of 15 mA/cm.sup.2.
[0011] FIGS. 4-7 show microscopic images of the anodic oxide film
of the aluminum sheet at different anodizing times under the
condition of FIG. 3.
[0012] FIG. 8 is similar to FIG. 3, but shows the potential-time
curve and the associated first-order differential curve of the
anodic oxide film formed by anodizing the aluminum sheet in a
sulfuric acid solution with a concentration of 10 wt % at a bath
temperature of 303K and a current density of 27 mA/cm.sup.2.
[0013] FIG. 9 shows a microscopic image of the anodic oxide film
formed on the aluminum sheet under the condition of FIG. 8.
[0014] FIG. 10 shows the potential-time curve and the associated
first-order differential curve of the anodic oxide film formed by
anodizing the aluminum sheet in a sulfuric acid solution with a
concentration of 20 wt % at a bath temperature of 283K and a
current density of 24 mA/cm.sup.2.
[0015] FIG. 11 shows a microscopic image of the anodic oxide film
formed on the aluminum sheet under the condition of FIG. 10.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0016] Referring to FIG. 1, a detection device for detecting an
anodic oxide film in an anodic oxidation treatment includes a power
source 1, a data acquisition unit 8, a data processor unit 10, a
display unit 11 and a container 14.
[0017] 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.
[0018] 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 FIG. 2. The
detecting method mainly includes the following steps: (a) obtaining
different potentials U of the anodic oxide film at different
anodizing times t by the data acquisition unit 8, recording and
processing the recorded potentials U and times t by the data
processing unit 10 to obtain a potential-time curve 20 and
displaying the potential-time curve 20 by the display unit 11 which
has a potential-time coordinates; (b) differentiating the different
potentials U at different times t by the data processing unit 10 to
obtain first-order differential values U' at different times t; (c)
generating a first-order differential curve 21 by the data
acquisition unit 8 according to the first-order differential value
U' at different times t and displaying the first-order differential
curve 21 by the display unit 11; and (d) judging the pore formation
capability of the anodic oxide film according to a shape of the
first-order differential curve 21. Details of the detection method
will be expatiated with specific anodic oxidation treatment
examples as follows.
[0019] 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/cm.sup.2.
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 FIG. 3.
[0020] 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, t.sub.U'max,
t.sub.Umax, and t.sub.Uconst. The anodizing time t.sub.U'max is the
time that the first-order differential curve 21 has a maximum
value: U'max. The anodizing time t.sub.Umax 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 t.sub.const 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 t.sub.const, 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 t.sub.U'max. The nanopore initiation and growth
stage is from t.sub.U'max to t.sub.Umax. The pore widening stage is
from t.sub.Umax to t.sub.Uconst. After the anodizing time
t.sub.Uconst 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.
[0021] Referring to FIG. 3 again, in the barrier layer formation
stage, the anodic oxide film initially and continuously grows on
the aluminum sheet 9. The initially formed anodic oxide film
significantly increases the electric resistance of the aluminum
sheet 9. The potential U of the anodic oxide film increases with
the increase of the electric resistance. An increasing rate of the
potential U of the anodic oxide film is more and more faster, and
thus the first-order differential value U' of the potential U
increases remarkably until reaching the maximum U'max. According to
the first-order differential curve 21, the maximum first-order
differential value U'max is about 3.96, and the anodizing time
t.sub.U'max is about 2.37s. In other words, a period for the
barrier layer formation stage is about 2.37s. An intersection point
A of the potential-time curve 20 with a vertical line of
t=t.sub.U'max is about (2.37s, 10.08V), i.e., the potential U of
the anodic oxide film reaching 10.08V at the end of the barrier
layer formation stage. FIG. 4 shows the anodic oxide film formed on
the aluminum sheet 9 in the barrier layer formation stage at the
anodizing time of about 2s, which is substantially a barrier layer
consisting mainly of amorphous type oxide which is compact and free
of pores.
[0022] 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 FIG. 3, the first-order differential value
U' of the potential U decreases to zero when the potential U of the
anodic oxide film reaches the maximum Umax. A point B (8.51s,
25.54V) indicates the peak of the potential-time curve 20, i.e.,
the maximum potential Umax of the anodic oxide film is about
25.54V, and the anodizing time t.sub.Umax is about 8.51s. The
nanopore initiation and growth stage is from 2.37s to 8.51s. In
this stage, initially, nanopores are formed on the surface of the
anodic oxide film, which result in the decrease of the first-order
differential value U' of the potential U. Then the current supplied
by the power source 1 to the aluminum sheet 9 for growing the
anodic oxide film thereon functions as a pore current and an anodic
oxide film formation current. The pore current increases because of
growing of the nanopores, while the formation current decreases due
to increase of the resistance of the anodic oxide film. Finally
affected by the pore current, nanopores persistently increase in
size to become pores. FIG. 5 shows the anodic oxide film formed on
the aluminum sheet 9 in the nanopore initiation and growth stage at
the anodizing time of about 6s, which has a plurality of pores.
[0023] In the pore widening stage, the anodic oxide film continues
to growth until it reaches the quasi-steady state at the anodizing
time t.sub.Uconst. 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 FIG. 3,
the anodizing time t.sub.Uconst is about 20.08s. At the anodizing
time t.sub.Uconst, the potential Uconst of the anodic oxide film
decreases to about 17.15V, as indicated by point C. As shown in
FIG. 6, the pores of the anodic oxide film at the anodizing time of
about 12s are apparent. After the anodizing time t.sub.Uconst,
i.e., in the quasi-steady state stage, the potential U of the
anodic oxide film is constant, being 17.15V, and thus the
first-order differential value U' of the potential U is also
constant, being zero. Both of the first-order differential curve 21
and the potential-time curve 20 in the quasi-steady state stage
after the anodizing time t.sub.Uconst are straight and
horizontal.
[0024] 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 U.sub.const. 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 U.sub.const.
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/cm.sup.2 has a
good quality. FIG. 7 shows the pores of the anodic oxide film at
the anodizing time of about 22s; it is obvious that the anodic
oxide film has an excellent pore formation.
[0025] FIG. 8 shows the potential-time curve 22 and the first-order
differential curve 23 of a second specific anodic oxidation
treatment. In this anodic oxidation treatment, the aluminum sheet 9
is anodized in the electrolyte 6 with a concentration of 10 wt % at
a bath temperature of 303K and a current density of 27 mA/cm.sup.2.
It is obvious that the first-order differential curve 23 has two
valleys in the pore widening stage, and thus the anodic oxide film
is poor in quality. As shown in FIG. 9, pitting is generated in the
anodic oxide film, and thus the pore formation of the anodic oxide
film is bad.
[0026] FIG. 10 shows the potential-time curve 24 and the
first-order differential curve 25 of a third specific anodic
oxidation treatment. In the third specific anodic oxidation
treatment, the aluminum sheet 9 is anodized in the electrolyte 6
with a concentration of 20 wt % at a bath temperature of 283K and a
current density of 24 mA/cm.sup.2. Similar to FIG. 8, the
first-order differential curve 25 in FIG. 10 has more than one
valleys in the pore widening stage, and thus the anodic oxide film
has a poor quality. As shown in FIG. 11, pitting also occurs in the
anodic oxide film.
[0027] 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.
* * * * *