Aluminum-modified polysilazanes for polymer-derived ceramic nanocomposites

Patent metadata

Field	Value
Publication number	US-9908905-B2
Application number	US-201514794322-A
Country	US
Kind code	B2
Filing date	Jul 8, 2015
Priority date	Jul 8, 2014
Publication date	Mar 6, 2018
Grant date	Mar 6, 2018

Abstract

Methods for synthesizing aluminum-modified silazanes, their use as polymer-derived ceramic precursors, and polymer-derived ceramics and carbon nanotube core/shell nanocomposites formed therefrom are disclosed.

First claim

We claim:

1. A ceramic nanocomposite comprising:
a plurality of carbon nanotubes having respective sidewalls; and
a layer of a polymer-derived ceramic adjacent said sidewalls, said polymer-derived ceramic being bonded to said sidewalls forming a protective shell thereon, wherein said polymer-derived ceramic is formed from an aluminum-modified silazane that is a room temperature liquid-phase polymer.

2. The ceramic nanocomposite of claim 1 , wherein said carbon nanotubes chemically interface with said aluminum-modified silazane.

3. The ceramic nanocomposite of claim 1 , wherein said silazane is poly(ureamethylvinyl)silazane.

4. The ceramic nanocomposite of claim 1 , wherein said ceramic nanocomposite is resistant to oxidation in flowing air at a temperature of up to about 1000° C.

5. The ceramic nanocomposite of claim 1 , wherein said ceramic nanocomposite is selected from the group consisting of nanowires, nanorods, nanosheets, and combinations thereof.

6. The ceramic nanocomposite of claim 1 , wherein said carbon nanotubes are selected from the group consisting of single-wall carbon nanotubes, double-wall carbon nanotubes, multi-wall carbon nanotubes, and mixtures thereof.

7. A structure comprising:
a substrate having a surface; and
a layer of the ceramic nanocomposite according to claim 1 adjacent said substrate surface.

8. The structure of claim 7 , wherein said layer is resistant to:
oxidation in flowing air at a temperature of up to about 1000° C.; or
laser irradiation up to about 8 kWcm −2 at a wavelength of about 1 μm at 10 kW average power, for about 10 seconds without burning, delamination, or deformation of said layer.

9. The structure of claim 7 , wherein said substrate is selected from the group consisting of metallic surfaces, natural woven fibers, synthetic woven fibers, natural nonwoven fibers, synthetic nonwoven fibers, natural or synthetic mats, natural or synthetic cloth, and combinations thereof.

10. The structure of claim 7 , wherein said substrate is an article of manufacture selected from the group consisting of high temperature sensors, turbine blades, engine parts, microelectronic components, solar cells, electrodes, protective coatings, tubing, wires, pump shafts, cylinders, spindles or sleeves, induction coils, and combinations thereof.

11. A method of forming the ceramic nanocomposite of claim 1 , said method comprising:
mixing the plurality of carbon nanotubes with the aluminum-modified silazane that is a room temperature liquid-phase polymer to yield respective sidewall-functionalized nanotubes comprising a layer of aluminum-modified silazane adjacent said nanotube sidewall;
crosslinking said layer of aluminum-modified silazane to yield a pre-ceramic nanocomposite comprising a solid pre-ceramic layer adjacent the sidewall of the carbon nanotubes, wherein said pre-ceramic layer comprises a crosslinked network of aluminum-modified silicon-based compounds coating the sidewall of the nanotubes; and
converting said pre-ceramic layer to ceramic to yield a ceramic nanocomposite comprising a layer of aluminum-modified polymer-derived ceramic coating the sidewall of the nanotubes.

12. The method of claim 11 , wherein said carbon nanotubes are first dispersed in a solvent system prior to said mixing with said aluminum-modified silazane.

13. The method of claim 12 , further comprising drying said sidewall-functionalized nanotubes to evaporate said solvent after said mixing.

14. The method of claim 11 , wherein said pre-ceramic layer comprises aluminum crosslinkages linking said silicon-based compounds.

15. The method of claim 11 , further comprising reducing said pre-ceramic nanocomposite into a free-flowing powder after said crosslinking prior to said converting.

16. The method of claim 15 , wherein said reducing comprises grinding, milling, pulverizing, and/or crushing the pre-ceramic composition into said powder.

17. The method of claim 11 , wherein said converting comprises pyrolyzing said crosslinked network of aluminum-modified silicon-based compounds.

18. The method of claim 11 , wherein said ceramic nanocomposite is a free-flowing black powder.

19. The method of claim 11 , wherein said aluminum-modified polymer-derived ceramic layer is characterized by aluminum substantially uniformly distributed throughout a polymer-derived ceramic network.

20. A method of forming a polymer-derived ceramic coating, said method comprising:
dispersing a ceramic nanocomposite powder in a solvent system to form a ceramic dispersion, said powder comprising discrete particulates, each of said particulates comprising the nanocomposite according to claim 1 ;
applying said ceramic dispersion to a substrate surface to form a layer thereon; and
heating said layer to evaporate said solvent system and yield a coated substrate having said ceramic nanocomposite coating adjacent said substrate surface.

21. The method of claim 20 , wherein said substrate comprises a metal selected from the group consisting of copper and alloys thereof.

22. The method of claim 20 , wherein said substrate has a planar surface.

23. The method of claim 20 , wherein said substrate has an uneven surface.

24. A powdered composition comprising a plurality of free-flowing particulates, each of said particulates consisting of a ceramic nanocomposite according to claim 1 .

25. The powdered composition of claim 24 , being substantially free of any binders and/or conducting agents.

26. The powdered composition of claim 24 , said powdered composition having a four-point electrical conductivity of at least 0.2 S/cm.

Assignees

• Univ Kansas State

Inventors

• Singh Gurpreet
• David Lamuel

Classifications

• B82B1/00

  Nanostructures formed by manipulation of individual atoms or molecules, or limited collections of atoms or molecules as discrete units · CPC title

• C07F7/21 Primary

  Cyclic compounds having at least one ring containing silicon, but no carbon in the ring · CPC title

• H01M4/661

  Metal or alloys, e.g. alloy coatings (H01M4/669 take precedence) · CPC title

• H01M4/62

  Selection of inactive substances as ingredients for active masses, e.g. binders, fillers · CPC title

• H01M10/052

  Li-accumulators · CPC title