Metal Matrix Composites

Metallic Prepregs
for the
Composite Industry



Metal matrix composites for applications such as selective reinforcement, crack mitigation, crack repair, rocket motor cases, armor, high stiffness aluminum, high stiffness metal.  

MetPreg® is a metal matrix composite (MMC) made from aluminum reinforced with high-strength, high-stiffness ceramic fibers to form an aluminum matrix composite with high strength and high stiffness at elevated temperatures. The development of MetPreg was a natural out-growth of Touchstone’s concerted materials R&D and industrial problem-solving efforts in support of the aluminum industry.

From a materials standpoint, aluminum (Al) is an attractive material for structural and thermal applications, primarily because of its availability, low cost, light weight, and high thermal conductivity.  It is 66% lighter per unit volume than iron (Fe) and 39% lighter than Ti-6-4.  When alloyed, Al has one of the highest strength-to-weight ratios of all the structural metals.  The initial use of Al alloys for engineering applications coincided with the development of motorized vehicles and the fledgling automotive industry in the early 19th century and has increased steadily over the last 100 years.  Al alloys are extensively used for electrical transmission lines, fracture-resistant parts for airframes and engines, missile bodies, fuel cells, and satellite components.  Al MMCs possess significantly better specific properties than monolithic aluminum alloys while maintaining good thermal conductivity.  For this reason they are of wide interest for structural and thermal applications in the aerospace and automotive industries.

One of the ways of classifying composite materials is on the basis of the shape and size of their reinforcements.  Composites are typically referred to as either continuous fiber or particulate (discontinuously reinforced) composites.  While discontinuous fiber composites have lower cost and are generally easier to process, applications for these materials are limited by their lower strength and stiffness.  Continuously reinforced composites, on the other hand, are much superior in properties, especially in the direction of the fibers.  Recent work on continuously reinforced Al composites has been directed towards developing lower-cost processing routes in order to drive these materials into defense-related and commercial products.

Touchstone has considerable experience in processing MMCs and is currently manufacturing and selling a pultruded aluminum MMC product in the form of a prepreg tape.  Touchstone has also developed an innovative processing technology for creating MMC cylinders and pressure vessels.  The technology uses an existing composites processing method known as filament winding.  Filament winding is one of the oldest manufacturing processes employed in the composites industry.  The process consists of pulling a roving or tow (a bundle of fibers or filaments) through the matrix material in a liquefied form (for example, a resin bath), impregnating or infiltrating the roving material with the matrix material, and “wrapping” the impregnated roving over a mandrel.  Filament winding is considered to be a very robust, inexpensive means of creating large, high-fiber-volume composite structures. 

Combining a low-cost filament winding process with high-performance MMC materials can lead to great improvements in the ability to produce affordable MMC structures by driving down costs and improving manufacturing capabilities.  These products are being marketed under the trade name MetPreg.

Several papers and properties tables on metal matrix composites have been added to this site.

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