U.S. patent application number 12/498455 was filed with the patent office on 2010-02-04 for electroplating method for magnesium and magnesium alloy.
This patent application is currently assigned to SHENZHEN FUTAIHONG PRECISION INDUSTRY CO., LTD.. Invention is credited to CHENG-SHIN CHEN, HONG-JUN QU, JONG-YI SU, REN-NING WANG.
Application Number | 20100025255 12/498455 |
Document ID | / |
Family ID | 41325000 |
Filed Date | 2010-02-04 |
United States Patent
Application |
20100025255 |
Kind Code |
A1 |
SU; JONG-YI ; et
al. |
February 4, 2010 |
ELECTROPLATING METHOD FOR MAGNESIUM AND MAGNESIUM ALLOY
Abstract
An electroplating method for magnesium and magnesium alloys,
comprising: providing a magnesium or magnesium alloy substrate and
pre-treating it to be cleaned; roughening the surface of the
substrate; activating the surface of the substrate; chemically
plating the substrate to form a nickel coating on its surface; and
electroplating the substrate to form, in order, a first nickel
coating, a copper coating, a second nickel coating, and a chromium
coating on the chemically produced nickel coating.
Inventors: |
SU; JONG-YI; (Shindian,
TW) ; CHEN; CHENG-SHIN; (Shindian, TW) ; WANG;
REN-NING; (Shenzhen City, CN) ; QU; HONG-JUN;
(Shenzhen City, CN) |
Correspondence
Address: |
PCE INDUSTRY, INC.;ATT. Steven Reiss
288 SOUTH MAYO AVENUE
CITY OF INDUSTRY
CA
91789
US
|
Assignee: |
SHENZHEN FUTAIHONG PRECISION
INDUSTRY CO., LTD.
ShenZhen City
CN
FIH (HONG KONG) LIMITED
Kowloon
HK
|
Family ID: |
41325000 |
Appl. No.: |
12/498455 |
Filed: |
July 7, 2009 |
Current U.S.
Class: |
205/176 |
Current CPC
Class: |
C23C 18/36 20130101;
C23C 18/1844 20130101; C23C 18/1653 20130101; C25D 3/12 20130101;
C25D 5/14 20130101; C25D 5/42 20130101; C25D 3/38 20130101; C25D
3/06 20130101; C25D 5/48 20130101 |
Class at
Publication: |
205/176 |
International
Class: |
C25D 5/10 20060101
C25D005/10 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 30, 2008 |
CN |
200810303204.7 |
Claims
1. An electroplating method for magnesium and magnesium alloys,
comprising: providing a magnesium or magnesium alloy substrate and
pre-treating it to be cleaned; roughening the surface of the
substrate; activating the surface of the substrate; chemically
plating the substrate to form a nickel coating on its surface; and
electroplating the substrate to form, in order, a first nickel
coating, a copper coating, a second nickel coating, and a chromium
coating on the chemically produced nickel coating.
2. The electroplating method as claimed in claim 1, wherein
roughening the surface of the substrate is carried out by dipping
the substrate in a roughening solution containing pyrophosphate in
a mass concentration of about 350-450 g/L and sodium carbonate in a
mass concentration of about 50-100 g/L for about 10-30 minutes at
about 55-65.degree. C.
3. The electroplating method as claimed in claim 1, wherein
activating the surface of the substrate is carried out by dipping
the substrate in an activating solution containing hydrofluoric
acid in a concentration by volume of about 150-300 ml/L for about
1-5 minutes at about 30-40.degree. C.
4. The electroplating method as claimed in claim 1, wherein
chemically plating the substrate is carried out by immersing the
substrate in a solution containing sodium hypophosphite in a mass
concentration of about 10-30 g/L and basic nickel carbonate in a
mass concentration of about 20-50 g/L for about 20-60 minutes at
about 70-90.degree. C.
5. The electroplating method as claimed in claim 1, wherein
electroplating the substrate to form the first nickel coating is
carried out in a first electrolyte containing a nickel sulphate
component in a mass concentration of about 240-300 g/L, a nickel
chloride component in a mass concentration of about 30-50 g/L, and
a boric acid component in a mass concentration of about 30-50 g/L
at about 50-55.degree. C.; the electric current density through the
first electrolyte is about 1-4 A/dm.sup.2; and the electroplating
lasts for about 4-10 minutes.
6. The electroplating method as claimed in claim 1, wherein
electroplating the substrate to form the copper coating is carried
out in a second electrolyte containing a copper sulphate component
in a mass concentration of about 180-220 g/L, and a sulfuric acid
component in a mass concentration of about 40-80 g/L at about
20-25.degree. C.; the electric current density through the second
electrolyte is about 1-3 A/dm.sup.2; and the electroplating lasts
for about 5-30 minutes.
7. The electroplating method as claimed in claim 5, wherein
electroplating the substrate to form the second nickel coating is
carried out in substantially the same way as was the forming the
first nickel coating.
8. The electroplating method as claimed in claim 1, wherein
electroplating the substrate to form the chromium coating is
carried out in a third electrolyte containing a chromium sulphate
component in a mass concentration of about 240-300 g/L, and a boric
acid component in a mass concentration of about 70-90 g/L at about
30-50.degree. C.; the electric current density through the third
electrolyte is about 1-15 A/dm.sup.2; and the electroplating lasts
for about 1-15 minutes.
9. The electroplating method as claimed in claim 8, wherein the
substrate is subjected to neutralization treatment after the
electroplating process in a neutralization solution including a
sulfuric acid component in a concentration by volume of about 20-50
ml/L, and an oxydol component in a concentration by volume of about
50-100 ml/L for about 1-3 minutes at about 20-30.degree. C.
10. The electroplating method as claimed in claim 1, wherein
pre-treating the substrate includes degreasing and cleaning the
substrate.
Description
BACKGROUND
[0001] 1. Technical Field
[0002] The present disclosure relates to an electroplating method
for magnesium and magnesium alloys.
[0003] 2. Description of Related Art
[0004] Magnesium and magnesium alloys are prone to corrosion such
as galvanic corrosion and therefore, should be surface treated
before being used. A typical surface treatment method now for
magnesium and magnesium alloys is electroplating. After
electroplating, the corrosion resistance and the metallic
appearance of the magnesium and magnesium alloys may be greatly
improved. However, there are some difficulties for electroplating
the magnesium and magnesium alloys because they are highly
chemically active. Additionally, during electroplating, magnesium
and magnesium alloys tend to react with metal ions contained in
electrolytes, which will affect the quality of the
electroplating.
[0005] Therefore, there is room for improvement within the art.
BRIEF DESCRIPTION OF THE DRAWING
[0006] Many aspects of the electroplating method for magnesium and
magnesium alloys can be better understood with reference to the
following drawing. The emphasis of the drawing is placed upon
clearly illustrating the principles of the electroplating method
for magnesium and magnesium alloys.
[0007] The FIGURE is a flow chart of a present embodiment of an
electroplating method for magnesium and magnesium alloys.
DETAILED DESCRIPTION
[0008] Referring to the FIGURE, an electroplating method for
magnesium and magnesium alloys may include the steps S10 to
S70.
[0009] In step S10, a magnesium or a magnesium alloy substrate is
provided. The substrate may be a housing of a mobile phone, a
digital camera, a personal digital assistant, or a note-book
computer. The substrate may also be a housing of a container.
[0010] In step S20, the substrate is pretreated. The pre-treating
step may comprise degreasing and cleaning the substrate. The
degreasing process may be carried out by dipping the substrate in a
degreasing solution for about 5-15 minutes. The mass concentration
of the degreasing solution is about 150-200 grams per liter (g/L).
The temperature of the degreasing solution is about 75-90.degree.
C. After the degreasing process, the substrate is removed from the
degreasing solution and bathed in water. Then, the substrate is
dipped in a sodium hydroxide solution for about 4-10 minutes to be
polished. The sodium hydroxide solution may further include
wax-removing agent(s). The mass concentration of the sodium
hydroxide is about 100-200 g/L, and the mass concentration of the
wax-removing agent(s) in the solution is about 40-80 g/L. The
temperature of the sodium hydroxide solution is about 75-90.degree.
C. After the cleaning process, the substrate is again bathed in
water.
[0011] In step S30, the surface of the substrate is roughened by
dipping the substrate in a roughening solution containing
roughening agent(s) and sodium carbonate for about 10-30 minutes.
The temperature of the roughening solution is about 55-65.degree.
C. The mass concentration of the sodium carbonate in the roughening
solution is about 50-100 g/L. The roughening agent(s) may be
pyrophosphate, the mass concentration of the pyrophosphate in the
roughening solution is about 350-450 g/L. During the roughening
process, the magnesium or magnesium alloy on the surface of the
substrate will chemically react with the compounds in the
roughening solution thereby becoming roughened. The roughened
surface of the substrate enhances the adhesion of metal plating to
the substrate in a subsequent process.
[0012] In step 40, the surface of the substrate is activated. The
activating process is carried out by dipping the substrate in an
activating solution containing hydrofluoric acid for about 1-5
minutes. The temperature of the activating solution is about
30-40.degree. C. Concentration by volume of the hydrofluoric acid
in the activating solution is about 150-300 ml/L. The solution may
further include activating agent(s). During the activating process,
a magnesium fluoride film is formed on the surface of the
substrate.
[0013] In step S50, the substrate is chemically plated to form a
nickel coating on it's surface. The chemical plating process is
carried out by immersing the substrate in a solution containing
sodium hypophosphite and basic nickel carbonate for about 20-60
minutes. The mass concentration of the sodium hypophosphite in the
solution is about 10-30 g/L, and the mass concentration of the
basic nickel carbonate in the solution is about 20-50 g/L. The
temperature of the solution is about 70-90.degree. C. During the
chemical plating, the magnesium fluoride film is dissolved, and
then nickel iron in the solution is deoxidized to nickel and
deposited on the substrate to form the nickel coating.
[0014] In step 60, the substrate is repeatedly electroplated to
form one or more metal coatings on the chemically produced nickel
coating. The electroplated coating may comprise a first nickel
coating, a copper coating, a second nickel coating, and a chromium
coating. The electroplating process may comprise: electroplating
the substrate to form a first nickel coating on the chemically
produced nickel coating; electroplating the substrate to form a
copper coating on the first nickel coating; electroplating the
substrate to form a second nickel coating on the copper coating;
and electroplating the substrate to form a chromium coating on the
second nickel coating. The electroplated coating presents good
appearance and enhances the corrosion resistance of the
substrate.
[0015] Electroplating the substrate to form the first nickel
coating may be carried out in a first electrolyte, with the
metallized surface of the substrate being a cathode, and a nickel
anode being provided and immersed in the first electrolyte. The
first electrolyte may contain a nickel sulphate component in a mass
concentration of about 240-300 g/L, a nickel chloride component in
a mass concentration of about 30-50 g/L, and a boric acid component
in a mass concentration of about 30-50 g/L. The temperature of the
first electrolyte is about 50-55.degree. C. The electric current
density through the first electrolyte is about 1-4 A/dm.sup.2.
Electroplating the substrate with the first nickel coating may last
for about 4-10 minutes. The first nickel coating enhances the
corrosion resistance of the substrate.
[0016] Electroplating the substrate to form the copper coating may
be carried out in a second electrolyte, with the metallized surface
of the substrate being a cathode, and a copper anode being provided
and immersed in the second electrolyte. The second electrolyte may
contain a copper sulphate component in a mass concentration of
about 180-220 g/L, and a sulfuric acid component in a mass
concentration of about 40-80 g/L. The temperature of the
electrolyte is about 20-25.degree. C. The electric current density
through the second electrolyte is about 1-3 A/dm.sup.2.
Electroplating the substrate with the copper coating may last for
about 5-30 minutes. Because the copper coating possesses good
malleability and low porosity, the bonding of the copper coating
and the first nickel coating is enhanced.
[0017] Electroplating the substrate to form the second nickel
coating may be the same to the electroplating of forming the first
nickel coating. The second nickel coating further enhances the
corrosion resistance of the substrate. Because of the copper
coating's good malleability and low porosity, the bonding of the
second nickel coating with the copper coating is enhanced.
[0018] Electroplating the substrate to form the chromium coating
may be carried out in a third electrolyte, with the metallized
surface of the substrate being a cathode, and a chromium anode
being provided and immersed in the third electrolyte. The third
electrolyte may contain a chromium sulphate component in a mass
concentration of about 240-300 g/L, and a boric acid component in a
mass concentration of about 70-90 g/L. The temperature of the third
electrolyte is about 30-50.degree. C. The electric current density
through the third electrolyte is about 1-15 A/dm.sup.2.
Electroplating the substrate with the chromium coating may last for
about 1-15 minutes. The chromium coating prepared by electroplating
in such an electrolyte and under such an electric current density
of the electrolyte has the property to bond well with the second
nickel coating, as described above. The chromium coating presents
high gloss appearance.
[0019] After being electroplated, the substrate is bathed in
water.
[0020] In step S70, the substrate is subjected to neutralization
treatment. The neutralization treatment is carried out by dipping
the substrate in a neutralization solution for about 1-3 minutes to
remove any residual electrolyte adhering to the substrate. The
neutralization solution includes a sulfuric acid component in a
concentration by volume of about 20-50 ml/L, and an oxydol
component in a concentration by volume of about 50-100 ml/L. The
temperature of the neutralization solution is about 20-30.degree.
C. After receiving neutralization treatment, the substrate is
bathed in water to be cleaned.
[0021] The addition of chemically plating the substrate before
electroplating prevents the problems that can occur from reaction
between magnesium and its alloys with ions in the electrolyte used
in electroplating. Thus producing better protected parts of
magnesium and magnesium alloys.
[0022] It is believed that the present 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.
* * * * *