Method and apparatus for structural coloration of metallic surfaces

Patent metadata

Field	Value
Publication number	US-2018010253-A1
Application number	US-201715644309-A
Country	US
Kind code	A1
Filing date	Jul 7, 2017
Priority date	Jul 8, 2016
Publication date	Jan 11, 2018
Grant date	—

Abstract

Materials for, and methods of, colorizing a metallic surface with micro-gratings using vibration cutting technologies are provided. Micro-gratings on aluminum, brass, and stainless steel surfaces can be rapidly created to effect, under illumination, at least one color observable in the visible spectrum using elliptical vibration texturing, a vibration-assisted mechanical cutting process. The modified metallic surface can display multiple visible colors, an iridescent effect caused by changes in one or more cutting parameters employed to produce the micro-gratings, the angle of illumination by an incident light, and/or the viewing angle of the surface under illumination.

First claim

What is claimed is:

1 . A method of modifying a metallic surface, the method comprising:
creating with a cutting tool on the metallic surface at least one series of periodic features perpendicular to a desired cutting direction, wherein the at least one series of periodic features are parallel or substantially parallel and the cutting tool is vibrated at a distinct frequency while simultaneously displaced along the desired cutting direction across the metallic surface, and wherein a rate of the displacement of the cutting tool is different from the distinct frequency of the vibration of the cutting tool, and wherein a value of the distinct frequency f is in a range of less than or equal to the ultrasonic range.

2 . The method according to claim 1 , wherein the rate of the displacement of the cutting tool is less than the distinct frequency of the vibration of the cutting tool.

3 . The method according to claim 1 , wherein a spacing d between adjacent periodic features perpendicular to the desired cutting direction is defined by the equation:

d
=

2

π



v

ω

,

wherein ν is the rate of the displacement of the cutting tool and ω is an angular frequency of the vibration of the cutting tool.

4 . The method according to claim 1 , wherein the metallic surface comprises aluminum, brass, titanium, zinc, magnesium, niobium, tantalum, iron, stainless steel, chromium, nickel, or an alloy of any combination thereof.

5 . The method according to claim 1 , wherein the metallic surface comprises aluminum, brass, or stainless steel.

6 . The method according to claim 1 , wherein the cutting tool comprises single-crystalline diamond.

7 . The method according claim 1 , wherein the vibration of the cutting tool comprises an elliptical trajectory having two orthogonal components with identical frequencies.

8 . A metallic surface prepared according to the method of claim 1 , capable of displaying light of a distinct value of wavelength λ, wherein the distinct value of the wavelength λ is determined by the equation:
d (sin θ i +θ m )= mλ,

wherein d is a spacing distance between adjacent periodic features perpendicular to the desired cutting direction, θ i is an angle of illumination by an incident light, θ m is an angle of viewing, and m is an integer indicating the order of diffraction of the incident light by the periodic features.

9 . The metallic surface according to claim 8 , wherein the spacing distance d is in a range of from 300 nm to 2000 nm.

10 . The metallic surface according to claim 8 , wherein the distinct value of the wavelength λ is in a range of from 380 nm to 750 nm.

11 . A method of producing an iridescent metallic surface, the method comprising:
defining on the metallic surface a plurality of distinct regions of the same or different shapes and sizes, wherein a number of distinct regions corresponds to a number of colors desired for the iridescent metallic surface to display; creating with a cutting tool on a first distinct region of the metallic surface at least one series of periodic features perpendicular to a desired cutting direction, wherein the at least one series of periodic features are parallel or substantially parallel, wherein the cutting tool is vibrated at a distinct frequency while simultaneously displaced along the desired cutting direction across the metallic surface, and wherein a rate of the displacement of the cutting tool is different from the distinct frequency of the vibration of the cutting tool; and repeating the treatment of the first distinct region of the metallic surface in each additional region of the metallic surface, wherein the distinct frequency of the vibration of the cutting tool is held constant while the rate of the displacement of the cutting tool varies from each distinct region to each other distinct region of the metallic surface, or wherein the rate of the displacement of the cutting tool is held constant while the distinct frequency of the vibration of the cutting tool varies from each distinct region to each other distinct region of the metallic surface.

12 . The method according to claim 11 , wherein the rate of the displacement of the cutting tool is less than the distinct frequency of the vibration of the cutting tool.

13 . The method according to claim 11 , wherein a spacing d between adjacent periodic features perpendicular to the desired cutting direction is defined by the equation:

d
=

2

π



v

ω

,

wherein ν is the rate of the displacement of the cutting tool and ω is an angular frequency of the vibration of the cutting tool.

14 . The method according to claim 11 , wherein the metallic surface comprises aluminum, brass, titanium, zinc, magnesium, niobium, tantalum, iron, stainless steel, chromium, nickel, or an alloy of any combination thereof.

15 . The method according to claim 11 , wherein the cutting tool comprises single-crystalline diamond.

16 . The method according to claim 11 , wherein the vibration of the cutting tool comprises an elliptical trajectory having two orthogonal components with identical frequencies.

17 . A metallic surface prepared according to claim 13 , capable of displaying light having at least one distinct value of wavelength λ, wherein the number of the at least one distinct values of λ is determined by the number of the distinct regions defined on the metallic surface, and wherein each of the at least one distinct value of 2 is determined by the equation:
d (sin θ i +θ m )= mλ,

wherein d is the spacing distance between adjacent periodic features in the desired cutting direction, θ i is an angle of illumination by an incident light, θ m is an angle of viewing, and m is an integer indicating the order of diffraction of the incident light.

18 . The metallic surface according to claim 17 , wherein the spacing distance d is in a range of from 300 nm to 2000 nm.

19 . The metallic surface according to claim 17 , displaying light of at least one distinct value of wavelength λ, wherein each of the at least one distinct value of wavelength λ is in a range of from 380 nm to 750 nm.

20 . An apparatus for treating a metallic surface, the apparatus comprising:
an actuated stage; a motion generator mounted on the actuated stage, the motion generator being configured to engage a cutting tool integrated therein in sinusoidal vibrating motion with the metallic surface at an adjustable frequency of less than or equal to the ultrasonic range; a linear motion actuator configured to displace the vibrating cutting tool across the metallic surface;

Assignees

• Univ Hong Kong Chinese

Inventors

• Guo Ping
• Yang Yang

Classifications

• C23C22/53

  Treatment of zinc or alloys based thereon · CPC title

• C23C22/57

  Treatment of magnesium or alloys based thereon · CPC title

• B05D7/14

  to metal, e.g. car bodies (involving a chemical reaction between the metal and the coating C23) · CPC title

• C23C22/56

  Treatment of aluminium or alloys based thereon · CPC title

• C23C22/58 Primary

  Treatment of other metallic material · CPC title