Method of Producing Hybrid Tubular Metal/Ceramic Composites and Resulting Products

Abstract

There are disclosed inventions relating to tubular hybrid metal / ceramic composites and the methods of making them wherein the ceramic chosen has a lower thermal expansion than that of the metal.

Description

CROSS REFERENCE TO RELATED APPLICATIONS [0001] The present invention is a continuation application of U.S. patent application Ser. No. 10 / 764,662, issuing as U.S. Pat. No. 7,153,465, entitled “Method of Producing Hybrid Tubular Metal / Ceramic Composites”, filed on Jan. 26, 2004, which application is a continuation-in-part application of U.S. patent application Ser. No. 09 / 929,873, now U.S. Pat. No. 6,699,810, entitled “Method of Producing Hybrid Metal / Ceramic Composites and Resultant Products”, filed on Aug. 14, 2001, and which application claims the benefit of the filing of U.S. Provisional Patent Application Ser. No. 60 / 442,932, entitled “Method of Producing Hybrid Metal / Ceramic Composites and Resultant Products”, filed on Jan. 27, 2003. The specifications and claims of all said applications are incorporated herein by reference. FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT [0002] The U.S. government has a paid-up license in this invention and the right in limited circumstances to re...

AI Technical Summary

Benefits of technology

This approach results in hybrid metal / ceramic composites with enhanced durability and thermal stability, allowing for longer service life and improved performance under high temperature and pressure conditions, as the ceramic matrix provides load-bearing properties and the metal maintains structural integrity.

Problems solved by technology

Ceramics, including ceramic composites, are inherently brittle, while metals are inherently ductile.

These inherent properties render the attachment of ceramics and ceramic composites to metal structures problematic.

While chemical vapor infiltration (CVI) technology is currently viewed as the industry leader, it is a slow, complex process with many inherent difficulties, including a corrosive gas environment, a high cost for process tooling and a substantial amount (15-25%) of residual porosity.

Although some of these issues have been mitigated by new CVI methods, few metals can tolerate the highly corrosive CVI atmosphere, and those that can (e.g., tungsten alloys) have very high specific gravities, adding substantial weight to the structure.

Although fiber-reinforced ceramics are much less brittle than their monolithic counterparts, they are not ductile like metal components.

In addition, dense ceramics and ceramic composites are difficult to machine.

For these and other reasons, conventional attachment strategies are inadequate.

However, because of the change in density associated with the conversion of the matrix precursor to the finished ceramic, repeated infiltration / firing cycles are required to produce a dense finished ceramic product.

Further, it has not been possible to utilize these prior procedures to include metallic elements as an integrally formed part of the finished ceramic product.

This is due to the fact that the CVI and conventional PIP processes require such high temperatures to convert the preceramic to the finished ceramic product that metallic elements processed therewith are adversely affected.

A particular problem encountered with tubular metal items such as gun barrels is that their service life is limited by erosion, which degrades the weapon's performance.

The high temperature and pressure which results when firing the weapon, together with the aggressive nature of the propellant combustion products, combine to produce thermochemical erosion in the chamber, while friction caused by the exiting projectiles, particularly tracer rounds, induces mechanical erosion in the rest of the barrel and muzzle.

These operating conditions often cause failure of the gun barrel due to thermal expansion of the metal, causing rupturing and / or distortion so as to make the barrel unusable.

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