Shape memory alloy coating using additive manufacturing

Abstract

A gear pump can include at least one gear having a plurality of gear teeth. At least the plurality of gear teeth can be additively manufactured and can include a substrate and a pitting resistant outer coating additively manufactured on the substrate and configured to prevent pitting due to cavitation. The substrate can include a substrate material and the pitting resistant outer coating includes a pitting resistant material different than the substrate material. The pitting resistant outer coating defines an outer surface layer of the gear teeth.

What is claimed is: 
     
         1 . A gear pump, comprising:
 at least one gear having a plurality of gear teeth, at least the plurality of gear teeth being additively manufactured and comprising:
 a substrate; and 
 a pitting resistant outer coating additively manufactured on the substrate and configured to prevent pitting due to cavitation, 
 wherein the substrate includes a substrate material and the pitting resistant outer coating includes a pitting resistant material different than the substrate material, wherein the pitting resistant outer coating defines an outer surface layer of the gear teeth. 
   
     
     
         2 . The gear pump of  claim 1 , wherein the pitting resistant outer coating further comprises a mixture section that includes a composition having a mixture of the substrate material and the pitting resistant material additively manufactured together. 
     
     
         3 . The gear pump of  claim 2 , wherein the mixture section is a gradient. 
     
     
         4 . The gear pump of  claim 3 , wherein the gradient includes an increasing concentration of the pitting resistant material toward the outer surface layer from the substrate. 
     
     
         5 . The gear pump of  claim 4 , wherein at least the outer surface layer defined by the pitting resistant outer coating only includes pitting resistant material. 
     
     
         6 . The gear pump of  claim 5 , wherein the outer surface layer is about 20 microns thick or more. 
     
     
         7 . The gear pump of  claim 6 , wherein the gradient is about 50 microns thick or more. 
     
     
         8 . The gear pump of  claim 1 , wherein the pitting resistant material includes a shape memory alloy. 
     
     
         9 . The gear pump of  claim 8 , wherein the shape memory alloy includes NiTi. 
     
     
         10 . The gear pump of  claim 9 , wherein the substrate material is steel. 
     
     
         11 . A method, comprising:
 additively manufacturing a pitting resistant outer coating on a substrate that is made of a substrate material to form a gear for a gear pump.   
     
     
         12 . The method of  claim 11 , wherein additively manufacturing includes adding a powder of a pitting resistant material to a powder of the substrate material during additive manufacturing, and successively increasing a concentration of the pitting resistant material in successive additive layers to create a gradient extending from the substrate toward an outer surface layer of the pitting resistant outer coating. 
     
     
         13 . The method of  claim 12 , wherein increasing the concentration includes increasing the concentration to pure pitting resistant material after creating the gradient to create the outer surface layer. 
     
     
         14 . The method of  claim 12 , wherein the pitting resistant material is NiTi. 
     
     
         15 . The method of  claim 12 , wherein the substrate material is steel. 
     
     
         16 . A gear for a gear pump, comprising:
 a plurality of gear teeth, at least the plurality of gear teeth being additively manufactured and comprising:
 a substrate; and 
 a pitting resistant outer coating additively manufactured on the substrate and configured to prevent pitting due to cavitation, 
 wherein the substrate includes a substrate material and the pitting resistant outer coating includes a pitting resistant material different than the substrate material, wherein the pitting resistant outer coating defines an outer surface layer of the gear teeth. 
   
     
     
         17 . The gear of  claim 16 , wherein the pitting resistant outer coating further comprises a mixture section that includes a composition having a mixture of the substrate material and the pitting resistant material additively manufactured together. 
     
     
         18 . The gear of  claim 17 , wherein the mixture section is a gradient. 
     
     
         19 . The gear of  claim 18 , wherein the gradient includes an increasing concentration of the pitting resistant material toward the outer surface layer from the substrate. 
     
     
         20 . The gear of  claim 19 , wherein at least the outer surface layer defined by the pitting resistant outer coating only includes pitting resistant material.