N211-059 TITLE: High Temperature, Low Dielectric Constant Ceramic Fibers for Missile Applications
RT&L FOCUS AREA(S): General Warfighting Requirements
TECHNOLOGY AREA(S): Weapons
The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), 22 CFR Parts 120-130, which controls the export and import of defense-related material and services, including export of sensitive technical data, or the Export Administration Regulation (EAR), 15 CFR Parts 730-774, which controls dual use items. Offerors must disclose any proposed use of foreign nationals (FNs), their country(ies) of origin, the type of visa or work permit possessed, and the statement of work (SOW) tasks intended for accomplishment by the FN(s) in accordance with section 3.5 of the Announcement. Offerors are advised foreign nationals proposed to perform on this topic may be restricted due to the technical data under US Export Control Laws.
OBJECTIVE: Develop advanced high temperature ceramic fibers exhibiting high strength, low dielectric constant, low loss tangent, high thermal stability, and high oxidation resistance for missile and projectile system applications.
DESCRIPTION: Missile components such as radomes and control surfaces are subjected to tremendous thermal stress during missile flight. Current missiles use high temperature metals for control surfaces and ceramics (such as silicon nitride or silica) for radomes. Future advanced missiles will require components with greater thermal shock resistance with properties such as those exhibited by ceramic matrix composites (CMCs). However, the only fibers available for incorporation into CMCs are fused silica ("quartz" fibers), Nextel aluminosilicate fibers from 3M, and Nicalon fibers. These fibers suffer from a limitation on service temperature, generally about 1000-1200�C for the oxide fibers, and 1400�C for silicon carbide fibers. In the past, there has been insufficient market potential to support commercial development of fibers for higher temperature service.
Higher temperature fibers are desired, with the capability of surviving 1500�C or higher. For radome applications, fibers with low dielectric constant and low loss tangent are needed. The desired values for dielectrtic properties, mechanical properties, and thermal properties depend on specifics of the radar system and overall weapon design, and can vary. There is no absolute limit for either, but the concepts are discussed in the reference by Walton [Ref 5]. Examples of possible compositions for high temperature, low-dielectric constant fibers include boron nitride (BN) and silicon nitride (Si3N4). Both types of fibers were produced experimentally in the 1975-1995 timeframe but are not available commercially. Availability of high temperature fibers possessing the desired combination of properties (such as high elastic modulus, low dielectric constant and loss tangent, and high strength to elevated temperatures) will enable the development of ceramic matrix composites with vastly improved high temperature properties compared to current CMCs.
Missile components needing these material technology improvements include radomes and control surfaces, since they tend to experience the worst of thermal heat stresses during high-speed flight. As such, the material solutions will need to have electrical properties conducive to radome functionality (e.g., low dielectric constant, low loss tangent) in addition to high thermal stability and high oxidation resistance necessary for both radomes and control surfaces.
Possible applications for the desired technology include tactical missiles, long range guided projectiles, and hypersonic vehicles.
PHASE I: Develop a concept for high temperature ceramic fiber materials that meets the parameters and applications in the Ddescription. Establish concept feasibility of the requirements through analysis, modeling, and experimentation of materials of interest. The Phase I Option, if exercised, will include the initial design specifications and capabilities description to build a prototype solution in Phase II.
PHASE II: Develop and deliver notional full-scale prototypes that demonstrate functionality under the required service conditions including thermal and mechanical stresses. Use evaluation and testing to include high temperature mechanical tests, thermal shock tests, electrical tests, non-destructive testing, and microstructural examinations to show the prototype will meet Navy performance requirements. Develop and propose a Phase III Development Plan to transition the technology to Navy.
PHASE III DUAL USE APPLICATIONS: Support the Navy in transitioning the technology to Navy use in the STANDARD Missile program or other missile and/or projectile programs that could benefit from the material advancement. Support the manufacturing of the components employing the technology developed under this topic and assist in extensive qualification testing defined by the Navy program.
Potential commercial uses for high-speed radome and control surface performance improvements exist in the commercial spacecraft and aircraft industries and satellite communications.
REFERENCES:
KEYWORDS: Missiles; Guided Projectiles; Radomes; Thermal Shock; Missile Erosion; Hypersonics.