Multi-Step Electrodeposition Technique for Hierarchical Porous Coatings with Tunable Wickability, Wettability and Durability

Abstract

Porous metal coatings are produced by multi-step electrodeposition method involving application of higher current density at lower duration and lower current density for longer durations. During higher current step, the evolved hydrogen bubbles serve as the self-collapsing templates to deposit the metal ions and during lower current density at longer duration step, the coating is applied to improve the bond strength. The multi-step depositions by alternating these steps provides the development of more complex porous structures that can have desired interconnectivity between the pores and have desired morphology, and desired wettability and wickability characteristics, and have a good bond strength between the coated layers as well as coated layers and the base substrate.

1 . A multi-step electrodeposition method comprising:
 providing an electrolyte comprising positive and negative ions;   placing an anode electrode and a metal substrate cathode electrode in the electrolyte; and   implementing a multi-step process between the anode electrode and the cathode electrode, wherein the multi-step process comprises three or more steps of alternating a low current density step sufficient to produce deposition of a metal layer but insufficient to produce dynamic templating deposition of metal on the substrate and a high current density step sufficient to produce dynamic templating deposition of metal on the substrate.   
     
     
         2 . The method of  claim 1 , wherein the multi-step method comprises:
 a first step comprising a low current density for long duration without evolution of hydrogen bubbles supporting dynamic templating deposition to provide a base layer to support the following deposition;   a second step comprising a high current density for a short duration with simultaneous deposition of metal and evolution of hydrogen bubbles and dynamic templating deposition; and   a third step comprising a low current density for long duration with deposition of metal without evolution of hydrogen bubbles supporting dynamic templating deposition.   
     
     
         3 . The method of  claim 2 , wherein the multi-step method further comprises:
 a fourth step comprising a high current density for a short duration with simultaneous deposition of metal and evolution of hydrogen bubbles supporting dynamic templating deposition; and   a fifth step comprising a low current density for long duration with deposition of metal without evolution of hydrogen bubbles supporting dynamic templating deposition.   
     
     
         4 . The method of  claim 3 , wherein the multi-step method further comprises:
 a sixth step comprising a high current density for a short duration with simultaneous deposition of metal and evolution of hydrogen bubbles supporting dynamic templating deposition; and   a seventh step comprising a low current density for long duration with deposition of metal without evolution of hydrogen bubbles supporting dynamic templating deposition.   
     
     
         5 . The method of  claim 1 , wherein the multi-step method comprises:
 a first step comprising a high current density for a short duration with deposition of metal and simultaneous evolution of hydrogen bubbles supporting dynamic templating deposition;   a second step comprising a low current density for long duration with deposition of metal without evolution of hydrogen bubbles supporting dynamic templating deposition;   a third step comprising a high current density for a short duration with deposition of metal and simultaneous evolution of hydrogen bubbles supporting dynamic templating deposition; and   a fourth step comprising a low current density for long duration with deposition of metal without evolution of hydrogen bubbles supporting dynamic templating deposition.   
     
     
         6 . The method of  claim 5 , wherein the multi-step method further comprises:
 a fifth step comprising a high current density for a short duration with deposition of metal and simultaneous evolution of hydrogen bubbles supporting dynamic templating deposition; and   a sixth step comprising a low current density for long duration with deposition of metal without evolution of hydrogen bubbles supporting dynamic templating deposition.   
     
     
         7 . The method of  claim 6 , wherein the multi-step method further comprises:
 a seventh step comprising a high current density for a short duration with simultaneous deposition of metal and evolution of hydrogen bubbles supporting dynamic templating deposition; and   an eighth step comprising a low current density for long duration with deposition of metal without evolution of hydrogen bubbles supporting dynamic templating deposition.   
     
     
         8 . The method of  claim 1 , wherein the metal comprises copper, aluminum, titanium, platinum, gold, palladium, silver and alloys thereof; graphite; or graphitic carbon. 
     
     
         9 . The method of  claim 1 , wherein the current density comprises from 10 to 2500 mA/cm 2  at a voltage from 2V to 100 V. 
     
     
         10 . The method of  claim 1 , wherein the electrolyte composition comprises CuSO 4 , H 2 SO 4  or H 2 O. 
     
     
         11 . The method of  claim 1 , wherein the multi-step process deposits a total layer thickness comprises from 5 to 500 μm. 
     
     
         12 . The method of  claim 1 , wherein the multi-step process deposits a total layer thickness comprises from 10 to 100 μm.