TECHNOLOGICAL ACHIEVEMENTS Photonic Sensors Computer-Aided Structural Design Artificial Vision Virtual Therapy FalconView Near-Field Antenna Measurements Millimeter Wave Radar Near-Field Sampling Applied Chaos Three-Dimensional Vision Solar Energy Fused Silica Radomes Pulse Combustion Monodisperse Aerosol Generation Digital Signal Processing BASIC DISCOVERIES TABLE of CONTENTS

Fused-Silica Radomes

Radomes — the structures that shield a missile's sensors — must withstand rapid high heating and harsh weather while maintaining a special quality that allows radio signals to pass through them.

Courtesy Defense Visualization Information Service GTRI scientists developed an improved technique for producing radomes, the structures that shield a missile's sensors, that are now widely used for intelligent missile systems such as the Patriot shown here.

That was part of the challenge of a research project first presented to the Engineering Experiment Station (now Georgia Tech Research Institute) in the late 1950s.

Highly regarded for their work in high-temperature ceramic materials, Tech researchers developed a slip-cast fused silica technique for forming refractories of massive size and complex shapes — structures such as radomes and missile nose cones, and rocket engine components.

Researchers developed several improvements to the fused-silica process over the years. In 1970, researchers discovered that manipulating the rate of heating, temperature and the time at temperature affect the development of the ceramic's mechanical strength in a phenomenon called sintering. The result was 50 percent stronger than previous efforts, yet maintained the requisite electromagnetic properties.

By the end of the 1980s, Tech researchers learned that adding aluminoborosilicate fibers to the mix strengthened the material. A further refinement was made when they found that short fibers - - meaning lengths 20 or 30 times their diameter versus fibers measuring 100 times their diameter — doubled radome strength with only a minimal loss of density.

The shorter fibers also prevented clumping during slip casting, a condition that results in lower density and strength, and large flaws.

Fibers increase the amount of energy needed to break the fused silica material. And should a crack develop, it would run into a fiber and follow the fiber along a tortuous path.

The radomes developed at Tech are widely used for intelligent missile systems such as the Patriot.

For more information, contact retired GTRI employees Joe Harris at 770-279-7291 or Jesse D. Walton at 404-634-2033.

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Last updated: October 25, 1999