Cold sprayed metal matrix composites
View Patent ↗A method of manufacturing homogenous metal matrix composite (MMC) powders and using the powders as the feedstock with cold spray deposition is described to produce composite coatings and freestanding bulk forms. Measured quantities of metal and ceramic powders having predetermined particle sizes are blended to produce homogeneous MMC powders. Spray parameters and procedures are controlled to produce dense, strong and well-bonded MMC coatings on any substrate.
1. A method for forming a metal matrix composite coating comprising:
providing a metal matrix powder having a particle range of from 20 to 55 microns;
providing a ceramic reinforcing powder having a particle size of from 1 to 30 microns;
combining from 5 to 50 volume percent of said ceramic reinforcing powder with a predetermined volume of said metal matrix powder;
wet blending said metal matrix powder with said ceramic reinforcing powder to form a metal matrix composite;
said wet blending step comprising adding a liquid carrier to form a slurry and adding high density zirconia or alumina balls in a range of from 20 to 50 wt % to said slurry;
drying said slurry to form a dry metal matrix composite material in powder form;
removing said balls and any large particles or agglomerates that may have formed;
providing a substrate;
forming a supersonic gas jet using a converging/diverging spray nozzle;
introducing said metal matrix composite powder into said supersonic gas jet; and
depositing said metal matrix composite powder at supersonic speed onto a surface of said substrate using said supersonic jet such that said metal matrix composite powder plastically deforms and bonds to said substrate and itself upon impact with said substrate surface trapping said reinforcing powder.
2. The method according to claim 1 wherein said metal matrix powder is selected from the group consisting of aluminum, nickel, titanium, silicon, and mixtures thereof.
3. The method according to claim 2 wherein said ceramic reinforcing powder is selected from the group consisting of boron carbide, tungsten carbide, silicon carbide, titanium carbide and mixtures thereof.
4. The method according to claim 2 , wherein said ceramic reinforcing powder is selected from the group consisting of silicon nitride, boron nitride, titanium nitride, and mixtures thereof.
5. The method according to claim 2 wherein said ceramic reinforcing powder is selected from the group consisting of aluminum oxide, zirconium oxide, silicon oxide and mixtures thereof.
6. The method according to claim 2 wherein said ceramic reinforcing powder is a combination of two or more carbides, nitrides, and oxides.
7. The method according to claim 6 wherein said wet blending step comprises adding a liquid carrier to said metal matrix powder and said ceramic reinforcing powder.
8. The method according to claim 7 wherein said blending step comprises using an inverse kinematic motion.
9. The method according to claim 8 further comprising decanting said liquid carrier from said metal matrix composite powder.
10. The method according to claim 1 wherein said removing step comprises sifting said metal matrix composite powder.
11. The method according to claim 10 further comprising feeding said metal matrix composite powder to said spray nozzle at a feed rate of from 1.0 grams/min to 3.0 grams/min at a pressure in the range of from 200 to 500 psi using a carrier gas selected from the group consisting of helium, nitrogen, an inert gas and mixtures thereof.
12. The method according to claim 11 wherein said carrier gas comprises helium and said feeding step comprises feeding said helium to said nozzle at a flow rate of from 5 SCFM to 50 SCFM.
13. The method according to claim 12 wherein said depositing step further comprises passing said metal matrix composite powder through said nozzle using a main gas selected from the group consisting of helium, nitrogen, and mixtures thereof at a main gas temperature in the range of from 200 degrees Fahrenheit to 1,250 degrees Fahrenheit and at a spray pressure in the range of from 200 psi to 500 psi.
14. The method according to claim 13 further comprising maintaining said nozzle at a distance from 10 mm to 50 mm from said surface.
15. The method according to claim 14 wherein said surface is the surface of deposited metal matrix composite or the substrate surface.
16. The method according to claim 1 wherein said combining step comprises combining from 15 to 25 volume percent of said ceramic reinforcing powder with a predetermined volume of said metal matrix powder.
17. The method according to claim 1 wherein said high density zirconia or alumina balls adding step comprises adding balls having a diameter in the range of from 2 to 4 mm.
18. The method according to claim 1 wherein said combining step comprises combining from 5 to 50 volume percent of a carbide having a 1 to 15 micron particle size with an aluminum alloy powder having a 20 to 50 micron particle size so as to produce a discontinuously reinforced aluminum powder.