Nanotube/metal substrate composites and methods for producing such composites

Abstract

Carbon nanotubes are grown directly on metal substrates using chemical vapor deposition. Metal substrates are comprised of catalysts which facilitate or promote the growth of carbon nanotubes. The nanotube coated metal substrates have applications including, but not limited to, heat transfer and thermal control, hydrogen storage, fuel cell catalytic reformers, electronics and semiconductors, implantable medical devices or prostheses, and tribological wear and protective coatings.

Description

BACKGROUND OF THE INVENTION [0001] One of the most significant spin-off products of fullerene research, which lead to the discovery of the C60 “buckyball” by the 1996 Nobel Prize laureates Curl, Kroto, and Smalley, are nanotubes based on carbon or other elements. Carbon nanotubes are fullerene-related structures which consist of graphene cylinders closed at either end with caps containing pentagonal rings. A carbon nanotube is essentially a seamless honeycomb graphite lattice rolled into a cylinder. The single-walled nanotube (SWNT) diameter is about 1-3 nm, with lengths of 100's to 1000's nanometers. The multi-walled nanotube is comprised of about 10-100 concentric tubes with an internal diameter of about 1-10 nm and an outer diameter of up to about 50 nm. The density of carbon nanotubes is about 1.3-1.4 g / cm3 and the surface areas are typically on the order of 103 m2 / g. [0002] Carbon nanotubes (CNT's) have been demonstrated for use in various electronic and chemical-mechanical dev...

AI Technical Summary

Benefits of technology

[0010] The present invention teaches a method and apparatus to prepare carbon nanotubes on metal substrate in a greatly simplified and advantageous manner for lower cost production of such composites. According to the present invention, carbon nanotubes (SWNT's or MWNT's) can be grown directly on metal substrates to produce metal-carbon nanotube composites. Our invention teaches a method for preparing the metal substrates and for growing nanotubes directly on the surface using chemical vapor deposition (CVD). Other nanotube growth processes such as laser vaporization can also utilize this technique and are contemplated as being within the scope of our invention.

[0011] Our invention is based upon the discovery that nanotubes can be grown directly onto metal substrates containing these catalysts which eliminates the need to separate the nanotubes prior to deposition or to combine the nanotubes with other substrates used in an application. Our method does not require the use of other support materials such as alumina or silica which are commonly used. This method also does not require the deposition of metal catalysts by solution or other means (e.g., plasma or ion implantation). Furthermore, the growth of carbon nanotubes directly onto metal substrates provides a production cost reduction since no additional materials (e.g., catalysts, supports, and digestion media) are needed.

Problems solved by technology

This digestion process can sometimes decompose or alter the nanotubes, and can be time-intensive and expensive.

The difficulty with state-of-the-art nanotube production processes is that the metals must first be deposited on a high surface area support such as alumina or silica, which must be dissolved to separate the nanotubes.

However, this approach did not recognize the advantages of using copper-based substrates with these and other metals to promote nanotube growth while at the same time maximizing thermal and electrical conductivity by using high thermally and electrically conductive materials.

Nor did the prior art recognize that cleaning preparation of the metal substrates is important to providing a reactive nanotube growth site.

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