Chemical method to create metal films on metal and ceramic substrates

Patent metadata

Field	Value
Publication number	US-10273582-B1
Application number	US-201615251035-A
Country	US
Kind code	B1
Filing date	Aug 30, 2016
Priority date	Aug 2, 2016
Publication date	Apr 30, 2019
Grant date	Apr 30, 2019

Abstract

The disclosure provides a method for generating a metallic coating on a substrate using a mixture comprising a precursor compound typically of chromium oxide, a chemical agent typically comprising NH z , and an inert transport fluid. The precursor compound and chemical agent are generally in the form of particulates having mean diameters less than about 100 microns, and the transport fluid is present in an amount sufficient to facilitate application of the mixture to a substrate. The mixture is applied to a substrate and the coated substrate is heated to a temperature exceeding the decomposition temperature of the chemical agent, generating a reducing gas typically comprising CO, H x , and/or NH x . In a particular embodiment, the precursor compound is CrO 2 , Cr 3 O 4 , CrO, or mixtures thereof, the chemical agent is urea, and the coated substrate is placed in a reactor having an inert atmosphere and subjected to a temperature of about 700° C. for about 5 minutes while maintaining an inert gas flow through the reactor.

First claim

What is claimed is:

1. A method of generating a metal coated substrate comprising generating a mixture solution comprising a precursor compound, a chemical agent selected from the group of chemical compounds consisting of a nitrogen-hydrogen containing molecule, ammonia, and a compound containing —NH z , where z is ≥1, that produces reducing gas upon thermal decomposition, and an inert transport fluid, where the precursor compound comprises a metal, and where the reducing gas comprises at least one of CO, H x , NH x , or mixtures thereof, where x is greater than or equal to 1, and where the inert transport fluid comprises at least 30 weight percent of the mixture solution;
coating a surface of a substrate with the mixture solution and forming an adherent layer of the mixture solution in contact with the surface of the substrate, thereby generating a mixture coated substrate;
heating the mixture coated substrate to a decomposition temperature where the decomposition temperature is sufficient to thermally decompose the chemical agent and produce the reducing gas;
maintaining the mixture coated substrate at the decomposition temperature for a period of time sufficient for the reducing gas to contact the precursor material and generate a metallic coating on the surface of the substrate, where the metallic coating comprises a surface layer coating the surface of the substrate and further comprises a layer of adhering material separated from the substrate by the surface layer, and where the surface layer comprises the metal comprising the precursor compound, thereby generating a treated substrate; and
polishing the treated substrate and removing some portion of the layer of adhering material while retaining the surface layer as a coating on the surface of the substrate, thereby generating the metal coated substrate.

2. The method of claim 1 where the precursor compound comprises a metal oxide or metal hydroxide.

3. The method of claim 2 where the chemical agent comprises NH 3 .

4. The method of claim 3 where the decomposition temperature is from about 400° C. to about 1200° C.

5. The method of claim 4 where the precursor compound comprises the metal oxide and the metal comprising the metal oxide is selected from the group consisting of chromium, nickel, or mixtures thereof.

6. The method of claim 1 where the mixture comprises a weight ratio of the chemical agent to the precursor compound of at least 3.

7. The method of claim 1 where the precursor compound comprises a plurality of first particles and the chemical agent comprises a second plurality of particles, where a mean diameter of the first plurality of particles is less than 500 microns and a mean diameter of the second plurality of particles is less than 500 microns, and where generating the mixture solution further comprises:
mixing the first plurality of particles and the second plurality of particles to generate a solid-solid heterogeneous mixture; and
adding the inert transport fluid to the solid-solid heterogeneous mixture in an amount such that the inert transport fluid comprises the at least 30 weight percent of the mixture solution, thereby generating the mixture solution.

8. The method of claim 1 further comprising:
placing the mixture coated substrate in a reactor;
exposing the mixture coated substrate to a heated inert atmosphere in the reactor, where the heated inert atmosphere has a temperature equal to the decomposition temperature, thereby heating the mixture comprising the mixture coated substrate;
generating a reaction gas as the reducing gas contacts the precursor compound;
exhausting some portion of the reaction gas from the reactor, thereby generating the treated substrate; and
removing the treated substrate from the reactor.

9. The method of claim 8 where an inert gas comprises at least 90 volume percent of the heated inert atmosphere, where the inert gas is selected from the group consisting of nitrogen, argon, helium, or mixtures thereof.

10. The method of claim 9 where contacting between the precursor compound and the reducing gas generates a zero valence metal, and where the metallic coating comprises the zero valence metal.

11. The method of claim 1 where the inert transport fluid is selecting from the group consisting of water, ethanol, or mixtures thereof.

12. The method of claim 1 wherein when the chemical agent comprises carbon, the layer of adhering material comprises some portion of the carbon comprising the chemical agent.

13. A method of generating a chromium coated substrate comprising:
generating a solid-solid heterogeneous mixture comprising a precursor compound and a chemical agent comprising urea, CO(NH 2 ) 2 , that produces reducing gas upon thermal decomposition at a decomposition temperature, where the precursor compound comprises a chromium oxide, and where the reducing gas comprises at least one of CO, H x , NH x , or mixtures thereof, where x is greater than or equal to 1, and where the decomposition temperature is from about 400° C. to about 1200° C. and where the precursor compound comprises a plurality of first particles and the chemical agent comprises a second plurality of particles, where a mean diameter of the first plurality of particles is less than 500 microns and a mean diameter of the second plurality of particles is less than 500 microns;
generating a mixture solution by adding an inert transport fluid to the solid-solid heterogeneous mixture in an amount such that the inert transport fluid comprises at least 30 weight percent of the mixture solution;
coating a surface of a substrate with the mixture solution and forming an adherent layer of the mixture solution in contact with the surface of the substrate, thereby generating a mixture coated substrate;
heating the mixture comprising the mixture coated substrate to a temperature at least equal to the decomposition temperature and thermally decomposing the chemical agent and producing the reducing gas; and
maintaining the mixture comprising the mixture coated substrate at the decomposition temperature for a period of time sufficient for the reducing gas to contact the precursor material and generate a chromium coating on the surface of the substrate, where the chromium coating comprises a surface layer coating the surface of the substrate and further comprises a layer of adhering material separated from the substrate by the surface layer, and where the surface layer comprises chromium comprising the chromium oxide of the precursor compound, thereby generating a treated substrate; and
polishing the treated substrate and removing some portion of the layer of adhering material while retaining the surface layer as a coating on the surface of the substrate, thereby generating the chromium coated substrate.

14. The method of claim 13 further comprising:
placing the mixture coated substrate in a reactor;
exposing the mixture coated substrate to a heated inert atmosphere in the reactor, where the heated inert atmosphere has a temperature equal to the decomposition temperature, thereby heating the mixture comprising the mixture coated substrate;
generating a reaction gas as the reducing gas contacts the precursor compound;
exhausting some portion of the reaction gas from the reactor, thereby generating the treated substrate; and
removing the treated substrate from the reactor.

15. The method of claim 14 where the mixture comprises a weight ratio of the chemical agent to the precursor compound of at least 2.

16. The method of claim 13 where the inert transport fluid is selecting from the group consisting of water, etha

Assignees

• Us Navy

Inventors

• Phillips Jonathan

Classifications

• B22F1/00

  Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties · CPC title

• C23C18/02

  by thermal decomposition · CPC title

• B22F9/00

  Making metallic powder or suspensions thereof · CPC title

• H01M4/00

  Electrodes · CPC title

• B82Y40/00

  Manufacture or treatment of nanostructures · CPC title