Composite compressor impeller with an erosion resistant coating and methods of manufacturing
View Patent ↗Impellers made of composite materials with flow path cavities covered by an erosion resistant coating are manufactured by covering removable molds having shapes corresponding to a negative geometry of the flow path cavities, with the erosion resistant coating using plating or thermal spraying. After shaping and curing a composite material around the molds covered with the erosion resistant coating, the molds are removed, while the erosion resistant coating remains on the composite impeller.
1. A method of manufacturing a composite impeller with flow path cavities having an erosion resistant coating, the method comprising:
providing molds having shapes corresponding to a negative geometry of the flow path cavities;
covering the molds with an erosion resistant coating;
shaping a composite material around the molds covered with the erosion resistant coating, according to a predetermined impeller geometry;
curing the composite material; and
removing the molds to leave the erosion resistant coating on the flow path cavities of the composite impeller, wherein covering the molds with the erosion resistant coating comprises: coating the molds with a sealant; applying a conductive paint over the sealant; and plating an erosion resistant layer over the conductive paint.
2. The method of claim 1 , wherein the composite material includes a resin.
3. The method of claim 1 , wherein the molds are made of a water-soluble material and removing the molds is performed by dissolving in a water-based solution.
4. The method of claim 1 , wherein the sealant is an epoxy paint.
5. The method of claim 1 , wherein the conductive paint includes silver.
6. The method of claim 1 , wherein the plating of the erosion resistant layer comprises:
plating a Ni-based layer over the conductive paint; and
plating the erosion resistant layer over the Ni-based layer using electroless nickel plating (ENP).
7. The method of claim 6 , wherein the plating of the Ni-based layer over the conductive paint is performed using a Woods nickel strike.
8. The method of claim 6 , wherein the Ni-based layer over the conductive paint has a thickness of less than 1 mil.
9. The method of claim 6 , wherein the erosion resistant layer plated using ENP includes diamonds of less than 2 μm size, in a proportion around 35% by volume.
10. The method of claim 1 , wherein the molds are made of a metal and removing the molds is performed by dissolving in an acid solution or in a basic solution.
11. The method of claim 10 , wherein the molds are made of copper or mild steel.
12. The method of claim 10 , wherein the removing of the mold is performed by dissolving in nitric acid.
13. The method of claim 10 , wherein the covering of the molds with the erosion resistant coating is performed by thermal spraying.
14. The method of claim 13 , wherein the erosion resistant coating is made of a ceramic and a metallic glue.
15. The method of claim 14 , wherein (a) the ceramic is WC and the metallic glue is one of (i) a combination of Co and Cr, (ii) Ni, or (iii) a combination of Ni and Cr, or (b) the ceramic is Cr2C3 and the metallic glue is a combination of Ni and Cr.