System and method for scale removal from a nickel-based superalloy component

Abstract

A system for cleaning scale from a nickel-based superalloy component is described. The system includes a molten salt, caustic alkaline solution, and an electrical charging device that provides at least 3 V DC to the molten salt bath. The system further includes a water rinse, a soap and water solution, an acid pickling solution, and an acetone rinse. The water rinse is air-agitated, the soap and water solution is acoustically coupled to an ultrasonic device, and the acid pickling solution is fluidly coupled to an agitator. The system includes a component positioning device structured to selectively, and successively, position the component within the molten salt bath, the water rinse, the soap and water solution, the acid pickling solution, the soap and water solution again, and the acetone rinse. The system includes a number of heating devices to provide selected temperatures to various selected solutions.

1 . A method comprising, in order:
 immersing a Ni-based superalloy component in a molten salt bath;   electrically charging the molten salt bath to at least 3 V DC;   immersing the component in water;   rinsing the component a first time in at least one of a soap and water solution and an acetone solution;   immersing the component in agitated acid pickling solution; and   rinsing the component a second time in at least one of the soap and water solution and the acetone solution.   
     
     
         2 . The method of  claim 1 , wherein the agitated acid pickling solution comprises 50% HNO 3  and 50% H 3 PO 4  by volume. 
     
     
         3 . The method of  claim 2 , further comprising heating the agitated acid pickling solution to at least 175° F. 
     
     
         4 . The method of  claim 1 , wherein the molten salt bath is a caustic alkaline solution. 
     
     
         5 . The method of  claim 1 , further comprising heating the molten salt bath to at least 900° F. 
     
     
         6 . The method of  claim 1 , wherein the electrically charging comprises electrically charging to between 3V and 6V DC with straight polarity. 
     
     
         7 . The method of  claim 1 , wherein the electrically charging comprises electrically charging to 3.5 volts DC at 1000 Amps. 
     
     
         8 . The method of  claim 1 , wherein the electrically charging comprises electrically charging to 4 volts DC at 1000 Amps. 
     
     
         9 . The method of  claim 1 , wherein the electrically charging comprises electrically charging to 5 volts DC at 1000 Amps. 
     
     
         10 . The method of  claim 1 , wherein the electrically charging comprises electrically charging to 6 volts DC at 1000 Amps. 
     
     
         11 . The method of  claim 1 , wherein the immersing the component in water further includes immersing the component in air agitated water. 
     
     
         12 . The method of  claim 1 , wherein the soap and water solution comprises an ammonia soap solution, the method further comprising applying ultrasonic energy to the soap and water solution. 
     
     
         13 . A method comprising, in order:
 immersing a Ni-based superalloy component in a molten salt bath comprising a caustic alkaline solution;   electrically charging the molten salt bath to at least 3 V DC;   immersing the component in air-agitated water;   rinsing the component a first time in an ammonia soap and water solution;   immersing the component in agitated acid pickling solution; and   rinsing the component a second time in the ammonia soap and water solution, rinsing the component a second time in the acetone solution.   
     
     
         14 . The method of  claim 13 , further comprising performing the electrically charging for at least 2 hours. 
     
     
         15 . The method of  claim 14 , further comprising heating the molten salt bath to at least 900° F. before the immersing the Ni-based superalloy component. 
     
     
         16 . The method of  claim 13 , further comprising performing the immersing the component in air-agitated water for at least five (5) minutes. 
     
     
         17 . The method of  claim 13 , further comprising immersing the component in the agitated acid pickling solution for at least one (1) hours. 
     
     
         18 . The method of  claim 17 , further comprising heating the agitated acid pickling solution to at least 175° F. before the immersing the component in the agitated acid pickling solution. 
     
     
         19 . The method of  claim 13 , further comprising heating the ammonia soap and water solution to at least 160° F. 
     
     
         20 . The method of  claim 19 , further wherein the rinsing the component the first time is performed for at least one hour, and wherein the rinsing the component the second time is performed for at least 30 minutes. 
     
     
         21 . The method of  claim 13 , further including rinsing the component again in an ultrasonic acetone rinse for at least 30 minutes to at least 160° F. 
     
     
         22 . A system, comprising:
 a molten salt, caustic alkaline solution (solution) and a first heating device thermally coupled to the solution, the first heating device structured to heat the solution to at least 900° F.;   an electrical charging device electrically coupled to the solution, the electrical charging device structured to provide at least 3 V DC at least 800 amps;   an ammonia soap and water solution and a second heating device thermally coupled to the ammonia soap and water solution, the second heating device structured to heat the ammonia soap and water solution to at least 160° F.;   an ultrasonic device acoustically coupled to the ammonia soap and water solution;   an acid solution and a third heating device thermally coupled to the acid solution, the third heating device structured to heat the acid solution to at least 175° F.;   an agitator fluidly coupled to the acid solution; and   a component positioning device structured to selectively contact a Ni-based superalloy component with the solution, the ammonia soap and water solution, and the acid solution.   
     
     
         23 . The system of  claim 22 , wherein the Ni-based superalloy component comprises at least one of an internal chamber and an internal crevice having a scale formed therein. 
     
     
         24 . The system of  claim 23 , wherein the scale comprises one of a sulfidation and an oxidation scale. 
     
     
         25 . The system of  claim 22 , further comprising an acetone rinse, and wherein the component positioning device is further structured to selectively contact the Ni-based superalloy component with the acetone rinse. 
     
     
         26 . The system of  claim 20 , wherein the acid solution comprises 50% HNO 3  and 50% H 3 PO 4  by volume. 
     
     
         27 . The system of  claim 20 , wherein the acid solution comprises 50% to 80% HNO 3  and 20% to 50% H 3 PO 4  by volume.