Methods for producing alloy deposits and controlling the nanostructure thereof using negative current pulsing electro-deposition, and articles incorporating such deposits

Abstract

Bipolar wave current, with both positive and negative current portions, is used to electrodeposit a nanocrystalline grain size deposit. Polarity Ratio is the ratio of the absolute value of the time integrated amplitude of negative polarity current and positive polarity current. Grain size can be precisely controlled in alloys of two or more chemical components, at least one of which is a metal, and at least one of which is most electro-active. Typically, although not always, the amount of the more electro-active material is preferentially lessened in the deposit during times of negative current. The deposit also exhibits superior macroscopic quality, being relatively crack and void free. Parameters of current density, duration of pulse portions, and composition of the bath are determined with reference to constitutive relations showing grain size as a function of deposit composition, and deposit composition as a function of Polarity Ratio, or, perhaps, a single relation showing grain size as a function of Polarity ratio. A specified grain size can be achieved by selecting a corresponding Polarity Ratio, based on these relations. Coatings can be in layers, each having an average grain size, which can vary layer to layer and also in a region in a graded fashion. Coatings can be chosen for environmental protection (corrosion, abrasion), decorative properties, and for the same uses as a hard chrome coating. A finished article may be built upon a substrate of electro-conductive plastic, or metal, including steels, aluminum, brass. The substrate may remain, or be removed.

What is claimed is: 
     
         1 . A method for depositing an alloy of a system comprising at least two elements, one of which being most electro-active and at least one of which being a metal, an alloy deposit having a specified nanocrystalline average grain size, comprising the steps of:
 a. providing a liquid comprising dissolved species of at least two elements of the system, at least one of which elements is the metal and at least one of which elements is the most electro-active;   b. providing a first electrode and a second electrode in the liquid, coupled to a power supply configured to supply electrical potential having periods of positive polarity and negative polarity at different times; and   c. driving the power supply to achieve the specified grain size deposit at the second electrode, with a non-constant electrical potential having positive polarity and negative polarity at different times, which times and polarities characterize a Polarity Ratio.   
     
     
         2 . The method of depositing of  claim 1 , further where said step of driving the power supply comprises driving the power supply to establish a Polarity Ratio, the Polarity Ratio having been selected with reference to a constitutive relation that relates the specified electrodeposited grain size to a corresponding Polarity Ratio. 
     
     
         3 . The method of depositing of  claim 2 , further where said step of driving the power supply comprises comparing the specified average grain size to at least one index grain size and driving the power supply to establish a Polarity Ratio, the Polarity Ratio having been selected with reference to a constitutive relation that relates the at least one index grain size to a corresponding Polarity Ratio and which also includes slope information that relates change in grain size to change in Polarity Ratio. 
     
     
         4 . The method of  claim 3 , the step of driving the power supply comprising driving the power supply with a non-constant electrical potential having both positive and negative polarity, the Polarity Ratio having been determined by:
 a. for a case that the slope information indicates a positive slope at the index grain size, for a specified grain size:
 i. relatively larger than an index grain size, using relatively larger Polarity Ratio than a Polarity Ratio corresponding to the index grain size; and 
 ii. relatively smaller than the index grain size, using relatively smaller Polarity Ratio than the Polarity Ratio corresponding to the index grain size; and 
   b. for a case that the slope information indicates a negative slope at the index grain size for a specified grain size relatively:
 i. larger than the index grain size, using relatively smaller Polarity Ratio than the Polarity Ratio corresponding to the index grain size; and 
 ii. smaller than the index grain size by using relatively larger Polarity Ratio than the Polarity Ratio corresponding to the index grain size. 
   
     
     
         5 . The method of  claim 4 , the step of using a relatively smaller Polarity Ratio comprising using relatively less time at negative polarity. 
     
     
         6 . The method of  claim 4 , the step of using relatively smaller Polarity Ratio comprising using relatively lower absolute value amplitude negative polarity. 
     
     
         7 . The method of  claim 4 , the step of using a relatively larger Polarity Ratio comprising using relatively more time at negative polarity. 
     
     
         8 . The method of  claim 1 , the step of using relatively larger Polarity Ratio comprising using relatively higher absolute value amplitude negative polarity. 
     
     
         9 . The method of  claim 1 , the step of driving the power supply comprising driving the power supply to generate a square wave. 
     
     
         10 . The method of  claim 1 , the step of driving the power supply comprising driving the power supply to generate a sine wave. 
     
     
         11 . The method of  claim 1 , the step of driving a power supply, comprising driving the power supply with a non-constant electrical potential, the Polarity Ratio supplied during deposition having been determined with reference to:
 a. a constitutive relation that relates the specified electrodeposited grain size to a corresponding proportion in the deposit of the active element; and   b. a constitutive relation that relates the corresponding proportion in the deposit of the active element to a Polarity Ratio supplied during deposition.   
     
     
         12 . The method of  claim 11 , the step of driving a power supply comprising the steps of driving the power supply with a non-constant electrical potential, the Polarity Ratio supplied during deposition having been determined by:
 a. identifying a proportion of active element that corresponds to the specified grain size; and   b. identifying a Polarity Ratio that corresponds to the identified proportion that corresponds to the specified electrodeposited grain size.   
     
     
         13 . The method of  claim 12 , the step of driving the power supply comprising:
 a. to achieve an electro-deposit composition having a relatively lower proportion of the relatively most active element than the proportion of that element in an index composition, using relatively greater Polarity Ratio than a Polarity Ratio that corresponds to that index composition based on the constitutive relation; and   b. to achieve an electro-deposit composition having a relatively greater proportion of the relatively most active element than the proportion of that element in the index composition, by using relatively lower Polarity Ratio than a Polarity Ratio that corresponds to that index composition.   
     
     
         14 . The method of  claim 1 , the deposit comprising a coating upon a substrate. 
     
     
         15 . The method of  claim 1 , the deposit comprising an object free-standing from any electrode. 
     
     
         16 . The method of  claim 14 , the substrate comprising steel. 
     
     
         17 . The method of  claim 14 , the substrate comprising aluminum. 
     
     
         18 . The method of  claim 14 , the substrate comprising stainless steel. 
     
     
         19 . The method of  claim 14 , the substrate comprising brass. 
     
     
         20 . The method of  claim 14 , the substrate comprising metal. 
     
     
         21 . The method of  claim 14 , the substrate comprising plastic having an electro-active surface. 
     
     
         22 . A method for depositing an alloy of a system comprising at least two elements, one of which being most electro-active and at least one of which elements is a metal, an alloy deposit having a specified nanocrystalline average grain size, comprising the steps of:
 a. providing a liquid comprising dissolved species of the at least two elements at least one of which elements is the metal and at least one of which elements is the most electro-active;   b. providing a first electrode and a second electrode in the liquid, coupled to a power supply configured to supply electrical potential having periods of positive polarity and negative polarity at different times; and   c. driving the power supply to achieve the specified grain size deposit at the second electrode, with a non-constant electrical potential having periods of positive polarity and negative polarity at different times, the Polarity Ratio supplied during deposition having been determined with reference to:
 i. a first constitutive relation that relates electrodeposited average grain size of a deposit to a proportion of the most electro-active metal in the deposit; and 
 ii. a second constitutive relation that relates the proportion of the most electro-active metal in a deposit to Polarity Ratio during deposition. 
   
     
     
         23 . The method of  claim 22 , further wherein the step of driving the power supply comprises the steps of:
 comparing the specified average grain size to at least one index grain size and, using the first constitutive relation, identifying a proportion of active metal in a deposit corresponding to the specified grain size;   comparing the corresponding proportion of active metal to at least one index proportion of active metal and using the second constitutive relationship, identifying a Polarity Ratio corresponding to the proportion of most active metal that corresponds to the specified grain size; and   driving the power supply to establish the identified Polarity Ratio, that corresponds to the proportion of most active metal that corresponds to the specified grain size.   
     
     
         24 . The method of  claim 23 , wherein said first constitutive relation includes an explicit correspondence between the specified grain size and a proportion of most active metal. 
     
     
         25 . The method of  claim 23 , wherein said first constitutive relation includes an explicit correspondence between an index grain size that differs from the specified grain size, and a proportion of active metal, and also includes slope information that relates change in grain size to change in proportion of most active metal, which enables deriving a proportion of most active metal that corresponds to the specified grain size. 
     
     
         26 . The method of  claim 23 , wherein the second constitutive relation includes an explicit correspondence between the proportion of most active metal that corresponds to the specified grain size and Polarity Ratio. 
     
     
         27 . The method of  claim 23 , wherein said second constitutive relation includes an explicit correspondence between an index proportion of most active metal that differs from the proportion of most active metal that corresponds to the specified grain size, and also includes slope information that relates change in proportion of most active metal to change in Polarity Ratio, which enables deriving a Polarity Ratio that corresponds to the proportion of most active metal that corresponds to the specified grain size. 
     
     
         28 . The method of  claim 22 , further where at least one of the first and second constitutive relations comprises a continuous function. 
     
     
         29 . The method of  claim 22 , further where at least one of the first and second constitutive relations comprises a table. 
     
     
         30 . The method of  claim 22 , further where at least one of the first and second constitutive relations comprises a point and slope information. 
     
     
         31 . The method of  claim 22 , further where at least one of the first and second constitutive relations comprises a formula. 
     
     
         32 . The method of  claim 22 , the deposit comprising a coating upon a substrate. 
     
     
         33 . The method of  claim 22 , the deposit comprising an object free-standing from any electrode. 
     
     
         34 . The method of  claim 22 , the substrate comprising steel. 
     
     
         35 . The method of  claim 22 , the substrate comprising aluminum. 
     
     
         36 . The method of  claim 22 , the substrate comprising stainless steel. 
     
     
         37 . The method of  claim 22 , the substrate comprising brass. 
     
     
         38 . The method of  claim 22 , the substrate comprising metal. 
     
     
         39 . The method of  claim 22 , the substrate comprising plastic with an electro-conductive surface. 
     
     
         40 . A method for determining parameters for depositing at an electrode, an alloy of a system comprising at least two elements, one of which being most electro-active and at least one of which being a metal, the alloy deposit having a specified nanocrystalline average grain size, the deposition using a first electrode and a second electrode, at which the alloy will deposit, the electrodes residing in a liquid comprising dissolved species of at least two elements of the system, at least one of which elements is the metal and at least one of which is the most electro-active element, the electrodes being driven by a power supply configured to provide electrical potential having periods of positive polarity and negative polarity at different times, the method of determining parameters comprising the steps of:
 a. selecting a bath composition comprising dissolved species of the at least two elements of the system;   b. determining a Polarity Ratio to supply to the electrodes during deposition by:
 i. determining a proportion of the most active element in the deposit composition that corresponds to the specified grain size, based on a constitutive relation that expresses average grain size as a function of proportion; and 
 ii. determining a Polarity Ratio supplied during deposit that corresponds to the proportion that corresponds to the specified grain size, based on a constitutive relation that expresses proportion as a function of Polarity Ratio. 
   
     
     
         41 . The method of  claim 40 , the constitutive relation that expresses grain size as a function of proportion comprising at least one point and slope information. 
     
     
         42 . The method of  claim 40 , the constitutive relation that expresses grain size as a function of proportion comprising a table. 
     
     
         43 . The method of  claim 40 , the constitutive relation that expresses grain size as a function of proportion comprising a mathematical function. 
     
     
         44 . The method of  claim 40 , the constitutive relation that expresses grain size as a function of proportion comprising a continuous function. 
     
     
         45 . The method of  claim 40 , the constitutive relation that expresses proportion as a function of supplied Polarity Ratio comprising at least one point and slope information. 
     
     
         46 . The method of  claim 40 , the constitutive relation that expresses proportion as a function of supplied Polarity Ratio comprising a table. 
     
     
         47 . The method of  claim 40 , the constitutive relation that expresses proportion as a function of supplied Polarity Ratio comprising a mathematical function. 
     
     
         48 . The method of  claim 40 , the constitutive relation that expresses proportion as a function of supplied Polarity Ratio comprising a continuous function. 
     
     
         49 . A method for determining parameters for depositing at an electrode, an alloy of a system comprising at least two elements, one of which being most electro-active and at least one of which being metal, the deposit having a specified nanocrystalline grain size, the deposition using a first electrode and a second electrode at which the alloy will deposit, the electrodes residing in a liquid comprising dissolved species of at least two elements of the system, at least one of which is the metal and at least one of which is the most electro-active, the electrodes being driven by a power supply that is configured to provide electrical potential having periods of positive polarity and negative polarity at different times, the method of determining parameters comprising the steps of:
 a. selecting a bath composition comprising dissolved species of the at least two elements,   b. determining a Polarity Ratio to supply to the electrodes during deposition, which corresponds to the specified grain size, based on a constitutive relation that expresses grain size as a function of supplied Polarity Ratio.   
     
     
         50 . The method of  claim 49 , the constitutive relation that expresses grain size as a function of Polarity Ratio comprising at least one point and slope information. 
     
     
         51 . The method of  claim 49 , the constitutive relation that expresses grain size as a function of Polarity Ratio comprising a table. 
     
     
         52 . The method of  claim 49 , the constitutive relation that expresses grain size as a function of Polarity Ratio comprising a mathematical function. 
     
     
         53 . The method of  claim 49 , the constitutive relation that expresses grain size as a function of Polarity Ratio comprising a continuous function. 
     
     
         54 . An article of manufacture of a metal alloy comprising at least two elements the article comprising:
 a. a first layer region having a nanocrystalline structure with a first average grain size;   b. adjacent said first layer region, and in contact therewith, a second layer region having a nanocrystalline structure with a second average grain size, which second size differs from the first size; and   further wherein the article exhibits failure modes that are dominated by phenomena other than the propagation of pre-existing cracks.   
     
     
         55 . The article of  claim 54 , the deposit comprising a coating upon a substrate. 
     
     
         56 . The article of  claim 55 , the coating comprising a coating that protects against corrosion. 
     
     
         57 . The article of  claim 55 , the coating comprising a coating that protects against abrasion. 
     
     
         58 . The article of  claim 55 , the coating comprising a decorative coating. 
     
     
         59 . The article of  claim 55 , the coating comprising a coating that functions as does a hard chrome coating. 
     
     
         60 . The article of  claim 54 , the deposit comprising an object free-standing from any electrode. 
     
     
         61 . The article of  claim 55 , the substrate comprising steel. 
     
     
         62 . The article of  claim 55 , the substrate comprising aluminum. 
     
     
         63 . The article of  claim 55 , the substrate comprising stainless steel. 
     
     
         64 . The article of  claim 55 , the substrate comprising brass. 
     
     
         65 . The article of  claim 55 , the substrate comprising metal. 
     
     
         66 . The article of  claim 55 , the substrate comprising plastic with an electro-conductive surface. 
     
     
         67 . The article of  claim 55 , further wherein, one of the layer regions comprises a region having a nanocrystalline structure with a graded variation in average grain size, such that the graded variation region has a first average grain size at a first location and spaced therefrom, at a second location, the graded variation region has a second, different average grain size, with varying average grain sizes between the first and second locations. 
     
     
         68 . An article of manufacture of a metal alloy comprising at least two elements the article comprising:
 a deposit having a nanocrystalline structure with a variation in average grain size, such that the deposit has:   a first average grain size at a first location; and   spaced therefrom, at a second location, a second, different average grain size, with varied average grain sizes between the first and second locations; and   further wherein the article exhibits failure modes that are dominated by phenomena other than crack propagation from pre-existing cracks.   
     
     
         69 . The article of  claim 68 , the deposit comprising a coating upon a substrate. 
     
     
         70 . The article of  claim 69 , the coating comprising a coating that protects against corrosion. 
     
     
         71 . The article of  claim 69 , the coating comprising a coating that protects against abrasion. 
     
     
         72 . The article of  claim 69 , the coating comprising a decorative coating. 
     
     
         73 . The article of  claim 69 , the coating comprising a coating that functions as does a hard chrome coating. 
     
     
         74 . The article of  claim 69 , the deposit comprising an object free-standing from any electrode. 
     
     
         75 . The article of  claim 69 , the substrate comprising steel. 
     
     
         76 . The article of  claim 69 , the substrate comprising aluminum. 
     
     
         77 . The article of  claim 69 , the substrate comprising stainless steel. 
     
     
         78 . The article of  claim 69 , the substrate comprising brass. 
     
     
         79 . The article of  claim 69 , the substrate comprising metal. 
     
     
         80 . The article of  claim 69 , the substrate comprising plastic with an electro-conductive surface. 
     
     
         81 . An article of manufacture of a metal alloy comprising at least two elements the article comprising:
 a. a first layer region having a nanocrystalline structure with a first average grain size;   b. adjacent said first layer region, and in contact therewith, a second layer region having a nanocrystalline structure with a second average grain size, which second size differs from the first size; and   further wherein the article exhibits failure modes that are dominated by phenomena other than crack initiation and propagation from pre-existing voids.   
     
     
         82 . The article of  claim 81 , further wherein, one of the layer regions comprises a region having a nanocrystalline structure with a variation in average grain size, such that the variation region has a first average grain size at a first location and spaced therefrom, at a second location, the variation region has a second, different average grain size, with varying average grain sizes between the first and second locations. 
     
     
         83 . An article of manufacture of a metal alloy comprising at least two elements, the article comprising:
 a region having a nanocrystalline structure with a variation in average grain size, such that the variation region has a first average grain size at a first location and spaced therefrom, at a second location, the variation region has a second, different average grain size, with varying average grain sizes between the first and second locations;   further wherein the article exhibits failure modes that are dominated by phenomena other than crack initiation and propagation from pre-existing voids.   
     
     
         84 . A method for depositing an alloy of a system comprising at least two elements, one of which being most electro-active and at least one of which being a metal, an alloy deposit having a first layer region having a nanocrystalline structure with a first average grain size adjacent said first layer region, and in contact therewith, a second layer region having a nanocrystalline structure with a second average grain size, which second size differs from the first size, comprising the steps of:
 a. providing a liquid comprising dissolved species of at least two elements of the system, at least one of which elements is the metal and at least one of which elements is the most electro-active;   b. providing a first electrode and a second electrode in the liquid, coupled to a power supply configured to supply electrical potential having periods of positive polarity and negative polarity at different times;   c. driving the power supply for a first period of time to achieve the first specified grain size deposit at the second electrode, with a non-constant electrical potential having positive polarity and negative polarity at different times, which times and polarities characterize a first Polarity Ratio; and;   d. driving the power supply for a second period of time to achieve the second specified grain size deposit at the second electrode, with a non-constant electrical potential having positive polarity and negative polarity at different times, which times and polarities characterize a second Polarity Ratio that differs from the first Polarity Ratio.   
     
     
         85 . The method of depositing of  claim 84 , further wherein, one of the layer regions comprises a region having a nanocrystalline structure with a variation in average grain size, such that the variation region has a first average grain size at a first location and spaced therefrom, at a second location, the variation region has a second, different average grain size, with varying average grain sizes between the first and second locations, the step of driving the power supply for a second period of time further comprises driving the power supply with a non-constant electrical potential having positive polarity and negative polarity at different times, which times and polarities characterize a range of non-constant Polarity Ratios that correspond to a range of different average grain sizes. 
     
     
         86 . A method for depositing an alloy of a system comprising at least two elements, one of which being most electro-active and at least one of which being a metal, comprising the steps of:
 a. providing an electroplating liquid comprising dissolved elements of the system;   b. providing a first electrode and a second electrode in the liquid;   c. driving the power supply for a first period of time with a non-constant electrical potential that characterizes a first Polarity Ratio; and;   d. driving the power supply for a second period of time with a non-constant electrical potential that characterize a second Polarity Ratio that differs from the first Polarity Ratio.   
     
     
         87 . A method for depositing an alloy of a system comprising at least two elements, one of which being most electro-active and at least one of which being a metal, an alloy deposit having a variation in average grain size, such that the variation region has a first average grain size at a first location and spaced therefrom, at a second location, the variation region has a second, different average grain size, with varying average grain sizes between the first and second locations comprising the steps of:
 a. providing a liquid comprising dissolved species of at least two elements of the system, at least one of which elements is the metal and at least one of which elements is the most electro-active;   b. providing a first electrode and a second electrode in the liquid, coupled to a power supply configured to supply electrical potential having periods of positive polarity and negative polarity at different times; and   c. driving the power supply for a period of time with a non-constant electrical potential having positive polarity and negative polarity at different times, which times and polarities characterize a range of non-constant Polarity Ratios, which correspond to a range of different average grain sizes.   
     
     
         88 . A method for depositing an alloy of a system comprising at least two elements, one of which being most electro-active and at least one of which being a metal, comprising the steps of:
 a. providing an electro-plating liquid comprising elements of the system;   b. providing a first electrode and a second electrode in the liquid, coupled to a power supply; and   c. driving the power supply for a period of time characterized by a range of non-constant Polarity Ratios, which correspond to a range of different average grain sizes.