Aqueous eletrodeposition of magnetic cobalt-samarium alloys

Abstract

Disclosed are methods and compositions for aqueous electrodeposition of rare earth-transitiona metal alloys (e.g., samarium-cobalt alloys). Also disclosed are nanostructured magnetic coatings comprising a magnetic alloy of a rare earth metal (e.g., samarium) and a transition metal (e.g., cobalt). This abstract is intended as a scanning tool for purposes of searching in the particular art and is not intended to be limiting of the present invention.

1 . A composition for enhancing the aqueous electrodeposition of rare earth-transition metal alloys comprising: a water soluble salt of samarium, a water soluble salt of cobalt, and a complexant. 
     
     
         2 . The composition of  claim 1 , wherein the water soluble salt of samarium is samarium sulfamate. 
     
     
         3 . The composition of  claim 1 , wherein the water soluble salt of cobalt is cobalt sulfate or cobalt sulfamate. 
     
     
         4 . The composition of  claim 1 , wherein the complexant is selected from one or more amine carboxylates, one or more hydroxycarboxylic acids, and combinations thereof. 
     
     
         5 . The composition of  claim 1 , further comprising one or more supporting electrolytes. 
     
     
         6 . The composition of  claim 5 , wherein the one or more supporting electrolytes is selected from ammonium sulfamate, ammounium sulfate, ammonium chloride, and mixtures thereof. 
     
     
         7 . The composition of  claim 1 , comprising from about 0.25M to about 2.0M of the water soluble salt of samarium, from about 0.01M to about 0.5M of the water soluble salt of cobalt, from about 0.05M to about 0.5M of the complexant, and from about 0M to about 3M of one or more supporting electrolytes. 
     
     
         8 . The composition of  claim 7 , comprising about 1M of the water soluble salt of samarium, about 0.05M of the water soluble salt of cobalt, about 0.15M of the complexant, and about 1M of the one or more supporting electrolytes. 
     
     
         9 . A method for electrodepositing a samarium-cobalt coating onto a conducting substrate, comprising:
 a. placing an aqueous solution containing a water soluble salt of samarium, a water soluble salt of cobalt, one or more supporting electrolytes, and a complexant into a plating bath,   b. placing an anode and the substrate to be coated into the bath and connecting the anode and the substrate to a power supply, with the substrate acting as a cathode,   c. adjusting the pH of the bath to a suitable operating level, and   d. applying a current through the anode and substrate causing the samarium and the cobalt to migrate to, and adhere to, the substrate.   
     
     
         10 . The method of  claim 9 , wherein the water soluble salt of samarium is samarium sulfamate. 
     
     
         11 . The method of  claim 9 , wherein the water soluble salt of cobalt is cobalt sulfate or cobalt sulfamate. 
     
     
         12 . The method of  claim 9 , wherein the complexant is selected from one or more amine carboxylates, one or more hydroxycarboxylic acids, and combinations thereof. 
     
     
         13 . The method of  claim 9 , wherein the one or more supporting electrolytes is selected from ammonium sulfamate, ammounium sulfate, ammonium chloride, and mixtures thereof. 
     
     
         14 . The method of  claim 9 , wherein the aqueous solution further comprises boric acid. 
     
     
         15 . The method of  claim 9 , wherein the aqueous solution comprises from about 0.25M to about 2.0M of the water soluble salt of samarium, from about 0.01M to about 0.5M of the water soluble salt of cobalt, from about 0.05M to about 0.5M of the complexant, and from about 0.0001M to about 3M of the supporting electrolytes. 
     
     
         16 . The method of  claim 15 , wherein the aqueous solution comprises about 1M of the water soluble salt of samarium, about 0.05M of the water soluble salt of cobalt, about 0.15M of the complexant, and about 1M of the supporting electrolytes. 
     
     
         17 . The method of  claim 9 , wherein a current density of from about 5 mA/cm 2  to about 600 mA/cm 2  is applied across the anode and cathode. 
     
     
         18 . The method of  claim 9 , wherein the current is applied with pulse current modifications varying with duty cycle and frequency. 
     
     
         19 . The method of  claim 9 , wherein the pH of the solution is from about 4 to about 6.5. 
     
     
         20 . The method of  claim 9 , wherein the solution temperature is adjusted to from about 25° C. to about 60° C. 
     
     
         21 . A samarium-cobalt coating produced by the method of  claim 9 . 
     
     
         22 . A nanostructured magnetic coating comprising a magnetic alloy of a rare earth metal and a transition metal. 
     
     
         23 . The nanostructured magnetic coating of  claim 22 , wherein the rare earth metal is samarium and wherein the transition metal is cobalt. 
     
     
         24 . The nanostructured magnetic coating of  claim 22 , wherein the coating is provided by electrodeposition from an aqueous solution. 
     
     
         25 . The nanostructured magnetic coating of  claim 22 , wherein the alloy comprises SmCo 5  or Sm 2 Co 17 .