Method to apply color coatings on alloys

A method to create a plasmonic colored surface, comprising the steps of:

• (a) anodizing an aluminum alloy substrate in an anodizing bath comprising phosphoric acid, at a constant temperature and a constant direct or pulsed current and/or voltage for a first time period to develop an anodizing layer of between 2 and 10 microns thick having one or more main pores;
• wherein the one or more main pores include one or more side pores;
• wherein the anodizing layer includes a barrier layer;
• (b) reducing the constant direct or pulsed current and/or voltage applied to the anodizing bath for a second time period to change a thickness of the barrier layer and change a width of the one or more main pores in the anodizing layer;
• (c) plating the aluminum alloy substrate in a plating bath at a first current that is increased over a third time period in accordance with a direct current (DC) plating current profile of the plating bath;
• (d) plating the aluminum alloy substrate in the plating bath at a second current for a fourth time period to at least partially fill the one or more main pores and the one or more side pores in the anodizing layer and develop a plasmonic surface;
• and
• (e) sealing the one or more main pores of the anodizing layer resulting in an air gap formed between the one or more main pores and a sealing layer.

A method, comprising the steps of:

• (a) pre-treating an aluminum alloy substrate;
• (b) activating the aluminum alloy substrate;
• (c) anodizing the aluminum alloy substrate in an anodizing bath comprising phosphoric acid, at a constant temperature and a constant voltage for a first time period, to develop an anodizing layer having one or more main pores;
• wherein the one or more main pores include one or more side pores;
• that includes a barrier layer;
• (d) reducing the constant voltage applied to the anodizing bath for a second time period to change a thickness of the barrier layer and change a width of the one or more main pores in the anodizing layer;
• (e) plating the aluminum alloy substrate in a plating bath via multiple plating stages to deposit metal nanorods into the one or more main pores and the one or more side pores of the anodizing layer;
• and
• (f) sealing the one or more main pores of the anodizing layer resulting in an air gap formed between the one or more main pores and a sealing layer.

A method to create a plasmonic colored surface, comprising the steps of:

• (a) anodizing a substrate in an anodizing bath comprising phosphoric acid, at a constant temperature and a constant voltage for a first time period to develop an anodizing layer having one or more main pores;
• wherein each of the one or more main pores include one or more side pores;
• wherein the anodizing layer includes a barrier layer;
• (b) reducing the constant voltage applied to the anodizing bath for a second time period to change a thickness of the barrier layer and change a width of the one or more main pores in the anodizing layer;
• (c) plating the substrate in a plating bath to fill or partially fill the one or more main pores and the one or more side pores and develop a plasmonic surface, at a first current that is increased over a third time period in accordance with a current profile of the plating bath;
• (d) plating the substrate in the plating bath at a second current for a fourth time period;
• and
• (e) sealing the one or more main pores of the anodizing layer resulting in an air gap formed between the one or more main pores and a sealing layer.