Methods for tailoring the surface topography of a nanocrystalline or amorphous metal or alloy and articles formed by such methods

Abstract

Electrochemical etching tailors topography of a nanocrystalline or amorphous metal or alloy, which may be produced by any method including, by electrochemical deposition. Common etching methods can be used. Topography can be controlled by varying parameters that produce the item or the etching parameters or both. The nanocrystalline article has a surface comprising at least two elements, at least one of which is metal, and one of which is more electrochemically active than the others. The active element has a definite spatial distribution in the workpiece, which bears a predecessor spatial relationship to the specified topography. Etching removes a portion of the active element preferentially, to achieve the specified topography. Control is possible regarding: roughness, color, particularly along a spectrum from silver through grey to black, reflectivity and the presence, distribution and number density of pits and channels, as well as their depth, width, size. Processing parameters that have been correlated in the Ni—W system to topography features include, for both the deposition phase and the etching phase of a nanocrystalline surface: duty cycle, current density, deposition duration, plating chemistry, polarity ratio. The relative influence of the processing parameters can be noted and correlated to establish a relationship between values for processing parameters and degree of topography feature. Control can be established over the topography features. Correlation can be made for any such system that exhibits a definite spatial distribution of an active element that bears a predecessor spatial relationship to a desired topography feature.

1 . A method of making an article having an at most nanocrystalline surface with a specified topography, the method comprising the steps of:
 a. providing a workpiece having a surface comprising an at most nanocrystalline material comprising at least two elements, at least one of which is metal, and one of which is more electrochemically active than the others, and which more electrochemically active element has a definite spatial distribution in the workpiece, which definite distribution bears a predecessor spatial relationship to the specified topography; and   b. etching the workpiece to remove a portion of the more electrochemically active element preferentially, as compared to any other components of the workpiece, to achieve the specified topography.   
     
     
         2 . The method of making an article of  claim 1 , the step of providing a workpiece comprising electrochemically depositing the at most nanocrystalline material on a substrate to achieve the definite spatial distribution of the more electrochemically active element. 
     
     
         3 . The method of making an article of  claim 2 , the step of electrochemically depositing comprising electrochemically depositing by using pulsed current. 
     
     
         4 . The method of  claim 3 , the step of electrochemically depositing comprising using pulsed current, having a polarity ratio. 
     
     
         5 . The method of making an article of  claim 1 , the step of etching comprising electrochemically etching the surface. 
     
     
         6 . The method of making an article of  claim 2 , the step of etching comprising electrochemically etching the surface. 
     
     
         7 . The method of making an article of  claim 5 , the step of etching comprising electrochemically etching using pulsed current. 
     
     
         8 . The method of making an article of  claim 7 , the step of electrochemically etching comprising using pulsed current, having a polarity ratio. 
     
     
         9 . The method of making an article of  claim 2 , the step of electrochemically depositing comprising electrochemically depositing by using pulsed current, having a depositing Polarity Ratio and the step of etching comprising electrochemically etching using pulsed current, having an etching Polarity Ratio. 
     
     
         10 . The method of making an article of  claim 6 , the steps of electrochemically depositing and electrochemically etching both being conducted in an electrolytic liquid. 
     
     
         11 . The method of making an article of  claim 10 , the steps of electrochemically depositing and electrochemically etching both being conducted in the same electrolytic liquid. 
     
     
         12 . The method of making an article of  claim 10 , the steps of electrochemically depositing and electrochemically etching being conducted in different electrolytic liquids. 
     
     
         13 . The method of making an article of  claim 2 , the step of electrochemically depositing being conducted by choosing deposition parameters that promote segregation of the most electrochemically active element to colony boundaries. 
     
     
         14 . The method of making an article of  claim 13 , the step of choosing parameters comprising using a relatively larger duty cycle sufficient to promote segregation of the most electrochemically active element to colony boundaries. 
     
     
         15 . The method of  claim 1 , the two elements comprising nickel (Ni) and tungsten (W). 
     
     
         16 . The method of  claim 10 , the two elements comprising nickel and tungsten. 
     
     
         17 . The method of  claim 15 , the step of providing comprising electrochemically depositing an at most nanocrystalline Ni—W surface. 
     
     
         18 . The method of  claim 2 , the step of providing comprising using a pulse current having a current density of between 0.01 A/cm 2  and 1.0 A/cm 2    
     
     
         19 . A method for making an article having an at most nanocrystalline surface with a specified topography, comprising the steps of:
 a. providing a workpiece having a surface comprising an at most nanocrystalline material comprising at least two elements, at least one of which is metal, and one of which is more electrochemically active than the others; and   b. etching the workpiece to remove a portion of the more electrochemically active element preferentially, as compared to any other components of the workpiece, to achieve the specified topography;   wherein, at least one of the following steps i and ii is conducted during the providing and etching a workpiece steps:
 i. the step of providing a workpiece is conducted with a value for a parameter for providing selected with reference to a constitutive relation that relates the providing parameter to the specified surface topography property; and 
 ii. the step of etching is conducted with a value for a parameter for etching, selected with reference to a constitutive relation that relates the etching parameter to the specified surface topography property. 
   
     
     
         20 . The method of making an article of  claim 19 , further, wherein the step of conducting at least one of the steps of providing a workpiece with a selected parameter value for providing; and etching with a selected etching parameter value, comprises at least one of the steps selected from the group consisting of:
 i. providing the surface by electrochemical deposition, choosing values for parameters of electrochemical deposition to segregate elements of different electrochemical activity preferentially relative to colony boundaries and interiors;   ii. electrochemically depositing the surface using current, having a relatively higher depositing duty cycle to achieve relatively larger colony structures;   iii. electrochemically depositing the surface using current, having a relatively higher depositing duty cycle to achieve an article topography exhibiting primarily a network of channels;   iv. electrochemically depositing the surface using current, having a relatively lower depositing duty cycle to achieve an article topography exhibiting primarily spaced apart pits;   v. electrochemically depositing the surface by using current, having a relatively lower depositing duty cycle to achieve an article topography exhibiting a relatively lower number density of pits;   vi. electrochemically depositing the surface by using current, having a relatively lower depositing duty cycle to achieve an article topography exhibiting relatively smaller diameter pits;   vii. electrochemically depositing by using current, having a relatively lower depositing duty cycle to achieve an article topography exhibiting a relatively shinier surface;   viii. electrochemically etching using current, having a relatively higher etching duty cycle to achieve an article topography exhibiting primarily relatively larger diameter pits;   ix. etching electrochemically using current, having a relatively higher etching duty cycle to achieve an article topography exhibiting primarily a relatively lower number density of pits;   x. electrochemically etching using current, having a relatively higher etching duty cycle to achieve an article topography exhibiting primarily relatively thicker solid ligaments between pits;   xi. electrochemically etching using current, having a relatively higher etching duty cycle to achieve an article topography exhibiting primarily a relatively duller, and relatively blacker appearance;   xii. electrochemically etching using a relatively higher etching current density to achieve an article topography exhibiting a relatively duller appearance;   xiii. electrochemically etching using a relatively higher etching current density to achieve an article topography exhibiting primarily relatively wider channels;   xiv. electrochemically etching using a relatively higher etching current density to achieve an article topography exhibiting primarily relatively larger pits;   xv. electrochemically etching using a relatively higher etching current density to achieve an article topography exhibiting primarily a relatively larger number density of pits;   xvi. electrochemically etching using a relatively higher etching current density to achieve an article topography exhibiting primarily a relatively shinier surface;   xvii. electrochemically etching using a relatively higher etching duty cycle to achieve an article topography exhibiting primarily relatively deeper pits;   xviii. electrochemically etching using a relatively higher etching current density to achieve an article topography exhibiting primarily relatively deeper pits; and   xix. electrochemically etching using a relatively higher etching current density to achieve an article topography exhibiting primarily relatively deeper channels.   
     
     
         21 . A method for making an article having an at most nanocrystalline surface, comprising the steps of:
 a. providing a workpiece having a surface comprising an at most nanocrystalline material, the material having a thickness, and comprising at least two elements, at least one of which is metal, and one of which is more electrochemically active than the others;   b. sleevelessly, electrochemically, etching the workpiece to remove a portion of the more electrochemically active element preferentially, as compared to any other components of the workpiece, to achieve a surface over which is distributed at least one surface feature of the group consisting of:
 i. a network of channels; and 
 ii. a plurality of pits; 
   which surface feature has a depth of less than the thickness of the at most nanocrystalline material; and   c. providing a lubricating material within the at least one surface feature.   
     
     
         22 . The method of  claim 21 , the step of sleevelessly etching comprising etching the workpiece to achieve a surface over which are distributed pits of controlled size. 
     
     
         23 . The method of  claim 21 , the step of sleevelessly etching comprising etching the workpiece to achieve a surface over which are distributed channels of controlled size. 
     
     
         24 . The method of  claim 21 , the step of sleevelessly etching comprising etching the workpiece to achieve a surface over which are distributed pits of controlled shape. 
     
     
         25 . The method of  claim 21 , the step of sleevelessly etching comprising etching the workpiece to achieve a surface over which are distributed pits at a controlled number density. 
     
     
         26 . The method of  claim 21 , the lubricating material comprising a fluid. 
     
     
         27 . The method of  claim 21 , the lubricating material comprising a particulate. 
     
     
         28 . A method of making an article having an at most nanocrystalline surface with a specified roughness, the method comprising the steps of:
 a. providing a workpiece having a surface comprising an at most nanocrystalline material comprising at least two elements, at least one of which is metal, and one of which is more electrochemically active than the others, and which more electrochemically active element has a definite spatial distribution in the workpiece, which distribution bears a predecessor spatial relationship to a topography, which topography functionally establishes the specified roughness; and   b. electrochemically etching the workpiece to remove a portion of the more electrochemically active element preferentially, as compared to any other components of the workpiece, values for parameters of etching having been selected with regard to the predecessor relationship to achieve the topography and thus, the specified roughness.   
     
     
         29 . The method of  claim 28 , the step of providing a workpiece comprising electrochemically depositing an at most nanocrystalline material using parameters of deposition selected to achieve the definite spatial distribution of the more electrochemically active element. 
     
     
         30 . A method of making an article having an at most nanocrystalline surface with a topography property selected from the group consisting of: roughness, blackness, shininess, number density of pits, size of pits, and spatial distribution of channels, said property having a specified degree, the method comprising the steps of:
 a. providing a workpiece having a surface comprising an at most nanocrystalline material comprising at least two elements, at least one of which is metal, and one of which is more electrochemically active than the others, and which more electrochemically active element has a definite spatial distribution in the workpiece, which distribution bears a predecessor spatial relationship to a topography, which topography functionally establishes the specified selected property to the specified degree; and   b. electrochemically etching the workpiece to remove a portion of the more electrochemically active element preferentially, as compared to any other components of the workpiece, parameters of etching having been selected with regard to the predecessor relationship to achieve the topography and thus, the specified selected property to the specified degree.