Method for dye-free coloring of one-time anodic aluminum oxide surface

Patent metadata

Field	Value
Publication number	US-10006140-B2
Application number	US-201615211355-A
Country	US
Kind code	B2
Filing date	Jul 15, 2016
Priority date	Jul 15, 2016
Publication date	Jun 26, 2018
Grant date	Jun 26, 2018

Abstract

A method for dye-free coloring of one-time anodic aluminum oxide surface is revealed. First provide a substrate containing aluminum. The substrate containing aluminum is anodized once at room temperature. The anodizing process includes a step of applying a pulse signal on the substrate containing aluminum for a first period of time. Thus a porous aluminum oxide layer is formed on surface of the substrate containing aluminum. The pulse signal includes a part with positive voltage and a part with negative voltage. Then a metal layer is deposited on the surface of the porous aluminum oxide layer. The porous aluminum oxide layer has a first interference wavelength. Next perform a linear regression of the first interference wavelength versus the first period of time. The absolute value of the slope of the regression line obtained ranges from 1.8 to 38.5. The absolute value is positively correlated with the positive voltage.

First claim

What is claimed is:

1. A method for dye-free coloring of a one-time anodic aluminum oxide surface, the method comprising the steps of:
providing a substrate containing aluminum;
performing one-time anodizing of the substrate containing aluminum at room temperature, the one-time anodizing including applying a pulse signal to the substrate containing aluminum for a plurality of first periods of time to thereby form a porous aluminum oxide layer on a surface of the substrate containing aluminum, wherein the pulse signal includes a part with positive voltage and a part with negative voltage;
depositing a metal film on the porous aluminum oxide layer;
performing a linear regression of a plurality of first interference wavelengths of the porous aluminum oxide layer having the metal film deposited thereon versus the plurality of first periods of time, wherein an absolute value of a slope of a regression line obtained ranges from 1.8 to 38.5 and is positively correlated with the positive voltage of the pulse signal; and
determining, from the linear regression, a desired positive voltage and a desired first period of anodizing time for obtaining a desired color of the porous aluminum oxide layer.

2. The method as claimed in claim 1 , wherein:
the positive voltage of the pulse signal is ranging from 20 Volts to 60 Volts;
the absolute value of the slope of the regression line is 2.0±0.5 when the positive voltage is set as 20 V;
the absolute value of the slope of the regression line is 3.5±0.5 when the positive voltage is set as 30 V;
the absolute value of the slope of the regression line is 6.4±0.5 when the positive voltage is set as 40 V;
the absolute value of the slope of the regression line is 16.8±0.5 when the positive voltage is set as 50 V; and
the absolute value of the slope of the regression line is 36.9±0.5 when the positive voltage is set as 60 V.

3. The method as claimed in claim 1 , wherein:
the method further includes a step of immersing the substrate containing aluminum with the porous aluminum oxide layer in an etching solution to perform a pore-widening process for a plurality of second periods of time at least once;
the porous aluminum oxide layer having the metal film deposited thereon has a plurality of second interference wavelengths;
a linear regression of the plurality of second interference wavelengths versus the plurality of second periods of time is carried out and an absolute value of a slope of a regression line obtained ranges from 1.5 to 8.0; and
the absolute value of the slope of the regression line between the second interference wavelength and the second period of time is negatively correlated with the positive voltage of the pulse signal.

4. The method as claimed in claim 3 , wherein:
the absolute value of the slope of the regression line is 7.3±0.5 when the positive voltage is set as 20 V;
the absolute value of the slope of the regression line is 3.4±0.5 when the positive voltage is set as 30 V; and
the absolute value of the slope of the regression line is 2.6±0.5 when the positive voltage is set as 40 V.

5. The method as claimed in claim 3 , wherein:
the surface containing aluminum with the porous aluminum oxide layer is disposed with a protective layer before the step of immersing the substrate containing aluminum with the porous aluminum oxide layer in the etching solution; and
the protective layer is removed after the pore-widening process and then the surface containing aluminum with the porous aluminum oxide layer is immersed in the etching solution to perform the pore-widening process again.

6. The method as claimed in claim 3 , wherein the step of immersing the substrate containing aluminum with the porous aluminum oxide layer in the etching solution to perform the pore-widening process at least once is for allowing the substrate containing aluminum to have various interference wavelengths and different optical properties/colors.

7. The method as claimed in claim 5 , wherein the protective layer is made from material selected from the group consisting of positive photoresist, negative photoresist, tape, and screen-printing inks.

8. The method as claimed in claim 1 , wherein the substrate containing aluminum is selected from the group consisting of a substrate made of pure aluminum, an aluminum alloy substrate, a substrate coated with an aluminum layer, and a substrate deposited with an aluminum alloy layer.

9. The method as claimed in claim 8 , wherein a thickness of the aluminum layer is ranging from 10 nm to 1000 nm.

10. The method as claimed in claim 1 , wherein the metal film is made from metal whose reflectivity is higher than 70% and a thickness of the metal film is ranging from 5 nm to 25 nm.

11. The method as claimed in claim 1 , wherein the metal film is made of material selected from the group consisting of platinum (Pt), aluminum (Al), silver (Ag), gold (Au), iron (Fe), nickel (Ni), cobalt (Co), chromium (Cr), titanium (Ti), Tantalum (Ta), copper (Cu), and their alloys.

12. The method as claimed in claim 1 , wherein the room temperature is ranging from 15 degrees Celsius (° C.) to 35° C.

13. The method as claimed in claim 1 , wherein the step of performing one-time anodizing of the substrate containing aluminum at room temperature is carried out in an acid solution whose concentration is ranging from 0.1 M to 0.9 M.

14. The method as claimed in claim 13 , wherein the acid solution is selected from the group consisting of oxalic acid solution, sulfuric acid solution and organic acid solution.

15. The method as claimed in claim 1 , wherein a waveform of the pulse signal is selected from the group consisting of a square wave, a sine wave, a triangle wave and a sawtooth wave.

16. The method as claimed in claim 1 , wherein an absolute value of the part of the pulse signal with positive voltage is larger than an absolute value of the part of the pulse signal with negative voltage.

17. The method as claimed in claim 1 , further comprising performing one-time anodizing of a target substrate containing aluminum at room temperature, the one-time anodizing including applying an ideal pulse signal to the target substrate containing aluminum for the desired first period of anodizing time to thereby form a porous aluminum oxide layer on a surface of the substrate containing aluminum, wherein the ideal pulse signal includes a part with the desired positive voltage and a part with negative voltage.

Assignees

• Univ Nat Cheng Kung

Inventors

• Chung Chen-Kuei
• Liao Ming-Wei
• Chu Bo-Yu
• Liao Shu-Hsien
• Chen Cheng-Hui

Classifications

• C25D11/024 Primary

  Anodisation under pulsed or modulated current or potential · CPC title

• C25D11/04

  of aluminium or alloys based thereon · CPC title

• C25D11/22 Primary

  for colouring layers · CPC title

• C25D11/24

  Chemical after-treatment · CPC title

• C25D11/10

  containing organic acids · CPC title