Hotblox Dielectric Materials

ATC's Hotblox Dielectrics are a line of injection moldable high temperature and moderately high temperature ceramic and polymer dielectric materials with dielectric constants between 1.5 and 5.5 with low loss. These materials have applications as radomes, elevated temperature antenna parts, antenna nosecones, etc. The Hotblox Dielectric materials are classified as the 70 series and 700 series. The 70 series materials are polymer composites with moderately high max. continuous use temperature or high-heat-short-duration applications. The 700 series materials are sintered ceramics with max. continuous use temperatures near 900 °C. Within both of the series there are several different dielectric constant materials available over the range mentioned above.

In addition, ATC can develop custom dielectric materials to suit a specific application.

General Properties

Hotblox 70 and 700 Series Dielectric Materials Properties

Missile Radomes

ATC has demonstrated the ability to injection mold large radomes. As part of a missile radome project, ATC injection molded radomes that are eighteen inches in height and seven inches in diameter. During this work, molding times, temperatures and procedures were optimized. A full-sized radome was manufactured free of defects. The process time, during this work, was approximately 2 hr. With further optimization the time could be reduced to 0.5 hr. or less.

Antenna Parts

ATC developed two dielectric materials for a conformal antenna where one part has half the dielectric constant of the second part. The parts needed to be injection molded to keep cost to a minimum. 

This antenna is a complex shape with two significant thin sections.  Current manufacturing studies of ceramic versions of the antenna parts have focused on machining the complex shapes from blocks of ceramic material. It has been estimated that machine time for the pieces for one antenna element is approximately eight hours. Since the parts are delicate, there will also be significant scrap in the production process.  ATC developed an efficient molding process for the Hotblox antenna pieces.  Currently, ATC is able to produce each piece in less than two hours.  ATC was able to accomplish this despite using a mold that was not designed for the Hotblox molding process.  ATC estimates that it could reduce production times to less than one half hour in the future.

IRBAS

The use of the Hotblox binder system as a binder for IRBAS has several potential advantages over the traditional processing of IRBAS. A Hotblox/IRBAS pre-ceramic material can be easily molded by injection, resin transfer or compression molding. These processes can be used to minimize scrap waste, improve surface finish and increase production speed. With modern injection molding and resin transfer molding equipment the entire process can be precisely controlled and the need to scrap parts minimized. With the molding processes available for Hotblox, surface finishes can be very good requiring little if any final machining or polishing. Also, modern molding equipment and automation allow for very fast production times.

Sub-scale (~4 in. tall) IRBAS/Hotblox radomes have been successfully molded by the resin transfer method. This radome was molded in a resin transfer mold and the rms surface roughness along the length of the radome is on average 1.7 microns. The mold that this radome was molded in was a machined steel proof-of-concept mold where the machining marks were hand-polished in an attempt to remove them. If a better surface finish were required, a more highly polished mold is all that is required reducing or eliminating final part polishing.

Contact ATC for more information on Hotblox Dielectric Materials.