U.S. patent application number 13/865634 was filed with the patent office on 2014-05-01 for surface treatment process for aluminum alloy and aluminum alloy article thereof.
This patent application is currently assigned to FIH (Hong Kong) Limited. The applicant listed for this patent is FIH (HONG KONG) LIMITED, SHENZHEN FUTAIHONG PRECISION INDUSTRY CO., LTD.. Invention is credited to Kai-Rong LIAO, Cheng-Yang XIONG, Shu-Xiang ZHOU.
Application Number | 20140116883 13/865634 |
Document ID | / |
Family ID | 50545994 |
Filed Date | 2014-05-01 |
United States Patent
Application |
20140116883 |
Kind Code |
A1 |
XIONG; Cheng-Yang ; et
al. |
May 1, 2014 |
SURFACE TREATMENT PROCESS FOR ALUMINUM ALLOY AND ALUMINUM ALLOY
ARTICLE THEREOF
Abstract
A surface treatment process for aluminum alloy includes the
steps of: providing an aluminum alloy substrate containing silicon
element; evenly distributing the silicon element in the substrate
by solution treating the substrate; removing the silicon element
at/near the surface of the substrate by acid treating the
substrate; forming a porous aluminum oxide film on the substrate by
anodizing the substrate; and staining the aluminum oxide film. An
aluminum alloy article treated by the process is also
described.
Inventors: |
XIONG; Cheng-Yang;
(Shenzhen, CN) ; ZHOU; Shu-Xiang; (Shenzhen,
CN) ; LIAO; Kai-Rong; (Shenzhen, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
PRECISION INDUSTRY CO., LTD.; SHENZHEN FUTAIHONG
FIH (HONG KONG) LIMITED |
Kowloon |
|
US
HK |
|
|
Assignee: |
FIH (Hong Kong) Limited
Kowloon
HK
SHENZHEN FUTAIHONG PRECISION INDUSTRY CO., LTD.
Shenzhen
CN
|
Family ID: |
50545994 |
Appl. No.: |
13/865634 |
Filed: |
April 18, 2013 |
Current U.S.
Class: |
205/50 ;
205/188 |
Current CPC
Class: |
C25D 11/246 20130101;
C25D 11/04 20130101; C25D 11/16 20130101; C25D 11/243 20130101;
C25D 11/08 20130101 |
Class at
Publication: |
205/50 ;
205/188 |
International
Class: |
C25D 11/16 20060101
C25D011/16; C25D 11/08 20060101 C25D011/08; C25D 11/24 20060101
C25D011/24 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 31, 2012 |
CN |
201210426259.3 |
Claims
1. A surface treatment process for aluminum alloy, comprising:
providing an aluminum alloy substrate comprising silicon element;
evenly distributing the silicon element in the substrate by
solution treating the substrate; removing the silicon element
at/near the surface of the substrate by acid treating the
substrate; forming a porous aluminum oxide film on the substrate by
anodizing the substrate; and staining the aluminum oxide film.
2. The process as claimed in claim 1, wherein solution treating the
substrate is carried out by positioning the substrate in a chamber
type electrical resistance furnace having an inner temperature of
about 495.degree. C. to about 525.degree. C. for about 8 hours to
about 10 hours.
3. The process as claimed in claim 1, wherein acid treating the
substrate is carried out by dipping the substrate in an acid
solution for about 5 min to about 10 min, the acid solution
comprises nitric acid and hydrofluoric acid in a volume ratio of
about 8-10:1-1.5.
4. The process as claimed in claim 3, wherein after the acid
treatment, the substrate comprises no silicon element from the
surface of the substrate to the depth of about 15 .mu.m to about 25
.mu.m of the substrate, the total content of the silicon element
contained in the substrate decreases about 1.3% to about 1.65%.
5. The process as claimed in claim 1, wherein anodizing the
substrate is carried out in a sulfuric solution having a
concentration of about 120 g/L to about 210 g/L for about 5 min to
about 65 min, the substrate acts as an anode, a stainless steel is
provided and acts as a cathode, a voltage of about 20 V to about
60V is applied to the anode and cathode, producing an electric
current of about 2 A/dm.sup.2 to about 6.5 A/dm.sup.2 in the
sulfuric solution; wherein during the anodizing process, the
sulfuric solution is kept at a temperature of about 3.degree. C. to
about 30.degree. C.
6. The process as claimed in claim 5, wherein the aluminum oxide
film has a thickness of about 5 .mu.m to about 12 .mu.m, the
aluminum oxide film defines a plurality of micro-pores, and
comprises no silicon element.
7. The process as claimed in claim 1, wherein staining the aluminum
oxide film is carried out using a colorant having a concentration
of about 0.2 g/L to about 4 g/L and a pH value of about 4-10, the
colorant has a temperature of about 30.degree. C. to about
60.degree. C., staining the aluminum oxide film last about 5 min to
about 20 min.
8. The process as claimed in claim 7, wherein the colorant is
xanthene dyes, methane dyes, coumarins dyes, cyanine dyes, stilbene
dyes, or oxazine dyes.
9. The process as claimed in claim 7, wherein the pH value of the
colorant is adjusted using an acetic acid, ammonia water, or a
sodium hydroxide.
10. The process as claimed in claim 1, further comprising a sealing
treatment to the aluminum oxide film using boiling water, vapor,
nickel acetate, nickel sulfate, potassium dichromate, or stearic
acid.
11. The process as claimed in claim 10, wherein a hydrated aluminum
oxide film is formed on the aluminum oxide film after the sealing
treatment.
12. The process as claimed in claim 1, further comprising a step of
quenching the substrate after the substrate being solution treated,
the quenching process is carried by dipping the substrate in water
having a temperature of about 20.degree. C. to about 25.degree. C.
for about 3 min to about 5 min.
13. The process as claimed in claim 1, further comprising a step of
chemical polishing the substrate before the substrate being
anodized.
14. The process as claimed in claim 13, wherein the chemical
polishing process comprises the following steps: the substrate is
dipped in a first polishing solution having a temperature of about
70.degree. C. to about 90.degree. C. for about 20 seconds to about
30 seconds, the first polishing solution comprises sulfuric acid
and phosphoric acid in a volume ratio of about 1-1.5:3-5; the
substrate is dipped in a second polishing solution having a
temperature of about 60.degree. C. to about 80.degree. C. for about
20 seconds to about 30 seconds, the second polishing solution
comprises nitric acid and phosphoric acid in a volume ratio of
about 1-1.5:3-5.
15. An aluminum alloy article, comprising: an aluminum alloy
substrate, the substrate comprising no silicon element from the
surface of the substrate to the depth of about 15 .mu.m to about 25
.mu.m of the substrate; an porous aluminum oxide film disposed on
the substrate, the aluminum oxide film comprising no silicon
element, and defining a plurality of micro-pores; and a hydrated
aluminum oxide film disposed on the aluminum oxide film.
16. The aluminum alloy article as claimed in claim 15, wherein the
aluminum oxide film has a thickness of about 5 .mu.m to about 12
.mu.m.
Description
BACKGROUND
[0001] 1. Technical Field
[0002] The present disclosure relates to a surface treatment
process for aluminum alloy and an aluminum alloy article treated by
the process.
[0003] 2. Description of Related Art
[0004] Aluminum alloys are widely used to manufacture housings of
electronic devices. The aluminum alloys are usually anodized and
stained to present colorful appearances. However, the color of the
aluminum alloy may not be uniform due to the silicon element
contained in the aluminum alloy. So, the silicon element is
necessary to be removed from the aluminum alloy.
[0005] The current method to remove the silicon element is to treat
the aluminum alloy using acid. However, treating the aluminum alloy
using acid can remove silicon element at/near the surface of the
aluminum alloy, but not all the silicon element in the aluminum
alloy. Commonly, the silicon element at/near the surface of the
aluminum alloy has a lower density than that of in the inner of the
aluminum alloy. As a result, despite removing the silicon element
at/near the surface, most of the silicon element in the inner would
transmit to the surface of the aluminum alloy to affect the
uniformity of the color.
[0006] Therefore, there is room for improvement within the art.
BRIEF DESCRIPTION OF THE DRAWING
[0007] Many aspects of the disclosure can be better understood with
reference to the following figure. The components in the figure are
not necessarily drawn to scale, the emphasis instead being placed
upon clearly illustrating the principles of the disclosure.
[0008] The figure is a cross-sectional view of an aluminum alloy
article in accordance with an exemplary embodiment.
DETAILED DESCRIPTION
[0009] A surface treatment process for an aluminum alloy may
include the following steps.
[0010] Referring to the figure, an aluminum alloy substrate 10 is
provided. The substrate 10 contains silicon element.
[0011] The substrate 10 is ultrasonically cleaned using absolute
ethanol for about 25 minutes (min) to about 35 min. Then the
substrate 10 is air-dried for about 2 min to about 3 min.
[0012] The substrate 10 is solution treated. A chamber type
electrical resistance furnace (not shown) is provided and set to
have an inner temperature of about 495.degree. C. to about
525.degree. C. The substrate 10 is positioned in the furnace to be
solution treated for about 8 hours to about 10 hours. During the
solution treatment, the silicon element in the substrate 10 takes
place a transmission to evenly distribute in the substrate 10 along
the thickness. That is, the solution treatment makes the density of
the silicon element in the substrate 10 consistent. Thus, the
density of the silicon element at/near the surface of the substrate
10 is greater than the density of the aluminum alloy which is not
solution treated.
[0013] The substrate 10 is removed from the furnace to be quenched
in 5 seconds. The quenching process is carried out by dipping the
substrate 10 in water for about 3 min to about 5 min. The water has
a temperature of about 20.degree. C. to about 25.degree. C.
[0014] The substrate 10 is acid treated to remove silicon element
at/near the surface of the substrate 10. The substrate 10 is dipped
in an acid solution for about 5 min to about 10 min The acid
solution contains nitric acid and hydrofluoric acid in a volume
ratio of about 8-10 : 1-1.5. During dipping, the silicon element
at/near the surface of the substrate 10 chemically reacts with the
hydrofluoric acid to produce silicon tetrafluoride that can be
dissolved in the acid solution, thereby the silicon element at/near
the surface of the substrate 10 is removed. After the acid
treatment, the substrate 10, from the surface to the depth of about
15 micrometers (pm) to about 25 .mu.m, contains no silicon element.
The total content of the silicon element contained in the substrate
10 decreases about 1.3% to about 1.65% after the acid treatment.
Since the silicon element has been evenly distributed in the
substrate 10 after the solution treatment, the acid treatment in
the embodiment can remove much more silicon element compared to the
conventional acid treatment.
[0015] The substrate 10 is chemically polished to smoothen the
surface and enhance the glossiness of the substrate 10. The
chemical polishing process may include the following steps:
[0016] The substrate 10 is dipped in a first polishing solution
having a temperature of about 70.degree. C. to about 90.degree. C.
for about 20 seconds to about 30 seconds. The first polishing
solution contains sulfuric acid and phosphoric acid in a volume
ratio of about 1-1.5 : 3-5. The sulfuric acid and the phosphoric
acid ionize H.sup.+ to chemically react with the aluminum oxide
that may formed on the surface of the substrate 10 in air to
produce Al.sup.3+ and H.sub.2O, thereby removing the aluminum oxide
and smoothening the surface of the substrate 10.
[0017] The substrate 10 is dipped in a second polishing solution
having a temperature of about 60.degree. C. to about 80.degree. C.
for about 20 seconds to about 30 seconds. The second polishing
solution contains nitric acid and phosphoric acid in a volume ratio
of about 1-1.5 : 1-3. The phosphoric acid can chemically react with
the aluminum contained in the substrate 10 to produce an aluminum
phosphate on the surface of the substrate 10, the aluminum
phosphate then dissolves in the nitric acid, thereby enhancing the
glossy of the substrate 10.
[0018] The substrate 10 is anodized. The anodizing process is
carried out in a sulfuric solution having a concentration of about
120 g/L to about 210 g/L for about 5 min to about 65 min. The
substrate 10 acts as an anode, a stainless steel is provided to act
as a cathode. A voltage of about 20 V to about 60 V is applied to
the anode and cathode, producing an electric current of about 2
A/dm.sup.2 to about 6.5 A/dm.sup.2 in the sulfuric solution. During
the anodizing process, the sulfuric acid is kept at a temperature
of about 3.degree. C. to about 30.degree. C. After the anodizing
process, an aluminum oxide film 12 is formed on the substrate 10
(see the figure). The aluminum oxide film 12 has a thickness of
about 5 .mu.m to about 12 .mu.m, and contains no silicon element
which would affect to the substantially staining to the aluminum
oxide film 12. Further, the solution treatment applied to the
substrate 10 can also prevent the transmission of the silicon
element in the inner of the substrate 10 to the surface of the
substrate 10 to affect the substantial staining process. The
aluminum oxide film 12 defines a plurality of micro-pores 121.
[0019] The aluminum oxide film 12 is stained using a colorant
having a concentration of about 0.2 g/L to about 4 g/L and a pH
value of about 4-10. The colorant may be xanthene dyes, methane
dyes, coumarins dyes, cyanine dyes, stilbene dyes, or oxazine dyes.
The pH value of the colorant can be adjusted using an acetic acid,
ammonia water, or sodium hydroxide. The colorant has a temperature
of about 30.degree. C. to about 60.degree. C. Staining the aluminum
oxide film 12 may last for about 5 min to about 20 min, allowing
the micro-pores 121 to be completely filled by the colorant.
[0020] A sealing treatment is applied to the aluminum oxide film
12, using boiling water, vapor, nickel acetate, nickel sulfate,
potassium dichromate, or stearic acid. In the embodiment, boiling
water is selected. The sealing treatment lasts for about 30 min to
about 45 min. After the sealing treatment, a hydrated aluminum
oxide film 14 is formed on the aluminum oxide film 12.
[0021] Referring to the figure, an aluminum alloy article 100 made
by the method above includes the aluminum alloy substrate 10, the
aluminum oxide film 12, and the hydrated aluminum oxide film 14.
The aluminum oxide film 12 is an anodic layer, and defines a
plurality of micro-pores 121 therein. The aluminum oxide film 12
has a thickness of about 5 .mu.m to about 12 .mu.m. The aluminum
oxide film 12 contains no silicon element, thus the aluminum oxide
film 12 has a uniform color after being stained.
[0022] Specific examples of the surface treatment process are
described below. The ultrasonic cleaning in these specific examples
is as described above and always the same.
Example 1
[0023] In air drying the substrate 10: the substrate 10 was dried
by a dryer (not shown) for 2 min.
[0024] In solution treating the substrate 10: the furnace had an
inner temperature of about 525.degree. C., the substrate 10 was
positioned in the furnace to be solution treated for about 8
hours.
[0025] In quenching the substrate 10: the substrate 10 was dipped
in water having a temperature of about 20.degree. C. for 5 min.
[0026] In acid treating the substrate 10: the substrate 10 was
dipped in the acid solution for 5 min The acid solution contained
nitric acid and hydrofluoric acid in a volume ratio of 8:1. After
the acid treatment, the total content of the silicon element
contained in the substrate 10 decreased about 1.3%.
[0027] In polishing the substrate 10: the substrate 10 was dipped
in a first polishing solution having a temperature of about
70.degree. C. for 20 seconds. The first polishing solution
contained sulfuric acid and phosphoric acid in a volume ratio of
1:3. Then the substrate 10 was dipped in a second polishing
solution having a temperature of about 60.degree. C. for 20
seconds. The second polishing solution contained nitric acid and
phosphoric acid in a volume ratio of about 1 : 1.
[0028] In anodizing the substrate 10: the anodizing process was
carried out in a sulfuric solution having a concentration of about
130 g/L for about 15 min. The substrate 10 acted as an anode, a
stainless steel was provided to act as a cathode. A voltage of
about 22 V was applied to the anode and cathode, producing an
electric current of about 2.3 A/dm.sup.2 in the sulfuric solution.
During the anodizing process, the sulfuric acid was kept at a
temperature of about 20.degree. C.
[0029] In staining the aluminum oxide film 12: the aluminum oxide
film 12 was stained using a xanthene dye having a concentration of
about 4 g/L and a pH value of about 5. The xanthene dye had a
temperature of about 30.degree. C. Staining the aluminum oxide film
12 lasted 5 min
[0030] In sealing the aluminum oxide film 12: boiling water was
selected to seal the micro-pores of the aluminum oxide film 12 for
30 min.
Example 2
[0031] In air drying the substrate 10: the substrate 10 was dried
by a dryer for 2 min.
[0032] In solution treating the substrate 10: the furnace had an
inner temperature of about 510.degree. C., the substrate 10 was
positioned in the furnace to be solution treated for about 9
hours.
[0033] In quenching the substrate 10: the substrate 10 was dipped
in water having a temperature of about 15.degree. C. for 5 min.
[0034] In acid treating the substrate 10: the substrate 10 was
dipped in the acid solution for 5 min The acid solution contained
nitric acid and hydrofluoric acid in a volume ratio of 10:1.5.
After the acid treatment, the total content of the silicon element
contained in the substrate 10 decreased about 1.5%.
[0035] In polishing the substrate 10: the substrate 10 was dipped
in a first polishing solution having a temperature of about
75.degree. C. for 20 seconds. The first polishing solution
contained sulfuric acid and phosphoric acid in a volume ratio of
about 1:5. Then the substrate 10 was dipped in a second polishing
solution having a temperature of about 70.degree. C. for 30
seconds. The second polishing solution contained nitric acid and
phosphoric acid in a volume ratio of about 1:1.
[0036] In anodizing the substrate 10: the anodizing process was
carried out in a sulfuric solution having a concentration of about
180 g/L for about 20 min. The substrate 10 acted as an anode, a
stainless steel was provided to act as a cathode. A voltage of
about 30 V was applied to the anode and cathode, producing an
electric current of about 3 A/dm.sup.2 in the sulfuric solution.
During the anodizing process, the sulfuric acid was kept at a
temperature of about 20.degree. C.
[0037] In staining the aluminum oxide film 12: the aluminum oxide
film 12 was stained using a xanthene dye having a concentration of
about 3 g/L and a pH value of about 6. The xanthene dye had a
temperature of about 40.degree. C. Staining of the aluminum oxide
film 12 lasted 10 min.
[0038] In sealing the aluminum oxide film 12: boiling water was
selected to seal the micro-pores of the aluminum oxide film 12 for
40 min.
Example 3
[0039] In air drying the substrate 10: the substrate 10 was dried
by a dryer for 3 min.
[0040] In solution treating the substrate 10: the furnace had an
inner temperature of about 495.degree. C., the substrate 10 was
positioned in the furnace to be solution treated for about 10
hours.
[0041] In quenching the substrate 10: the substrate 10 was dipped
in water having a temperature of about 20.degree. C. for 5 min.
[0042] In acid treating the substrate 10: the substrate 10 was
dipped in the acid solution for 10 min The acid solution contained
nitric acid and hydrofluoric acid in a volume ratio of 9:1. After
the acid treatment, the total content of the silicon element
contained in the substrate 10 decreased about 1.65%.
[0043] In polishing the substrate 10: the substrate 10 was dipped
in a first polishing solution having a temperature of about
80.degree. C. for 30 seconds. The first polishing solution
contained sulfuric acid and phosphoric acid in a volume ratio of
about 1:4. Then the substrate 10 was dipped in a second polishing
solution having a temperature of about 80.degree. C. for 30
seconds. The second polishing solution contained nitric acid and
phosphoric acid in a volume ratio of about 1:2.
[0044] In anodizing the substrate 10: the anodizing process was
carried out in a sulfuric solution having a concentration of about
200 g/L for about 60 min. The substrate 10 acted as an anode, a
stainless steel was provided to act as a cathode. A voltage of
about 55 V was applied to the anode and cathode, producing an
electric current of about 5.5 A/dm.sup.2 in the sulfuric solution.
During the anodizing process, the sulfuric acid was kept at a
temperature of about 5.degree. C.
[0045] In staining the aluminum oxide film 12: the aluminum oxide
film 12 was stained using a xanthene dye having a concentration of
about 1 g/L and a pH value of about 5. The xanthene dye had a
temperature of about 60.degree. C. Staining the aluminum oxide film
12 lasted 20 min.
[0046] In sealing the aluminum oxide film 12: boiling water was
selected to seal the micro-pores of the aluminum oxide film 12 for
35 min.
[0047] It is believed that the exemplary embodiment and its
advantages will be understood from the foregoing description, and
it will be apparent that various changes may be made thereto
without departing from the spirit and scope of the disclosure or
sacrificing all of its advantages, the examples hereinbefore
described merely being preferred or exemplary embodiment of the
disclosure.
* * * * *