AAWSAP DIRD, Materials for Advanced Aerospace Platforms, January 2010

This Defense Intelligence Reference Document, DIA-08-0912-008, is dated 12 January 2010. It was prepared by the Defense Warning Office's Acquisition Support Division at the Defense Intelligence Agency as one of a series of FY 2009 technology reports under the Advanced Aerospace Weapon System Applications program. It reviews materials for launch vehicles, space vehicles and reusable rocket engines, including aluminum alloys, polymer and metal matrix composites, titanium and nickel alloys, and titanium aluminides. It concludes that newer materials and integrated design could improve on the space shuttle.

From the source:Release of 2026-09-18 Incident: 1/12/10, Las Vegas, Nevada. Released with redactions. This document is a Defense Intelligence Reference Document (DIRD), a technical reference format used by the Defense Intelligence Agency (DIA) to capture baseline knowledge on a specific topic for later analytic use. DIRDs are best understood as reference and synthesis products rather than as original research. It is one of 38 DIRDs produced under the Advanced Aerospace Weapon System Applications Program (AAWSAP) between 2009 and 2011. Because AAWSAP’s scope permitted a broad range of supporting topics, not every DIRD in the series directly concerns aerospace systems or future threat assessment. The following summary reflects the DIRD’s scope and framing at the time of writing and should not be read as implying current validation of the concepts discussed. This DIRD surveys the structural materials needed for advanced aerospace platforms and argues that material choice cannot be separated from overall vehicle design, because launch vehicles, space vehicles, reusable systems, and propulsion hardware each face different temperature, durability, weight, and manufacturing constraints. The report reviews a range of candidate material classes, including advanced aluminum alloys; polymer-, aluminum-, and titanium-matrix composites; titanium alloys; nickel-base alloys; refractory metals; ceramic-matrix composites; carbon-carbon composites; and titanium aluminides. It emphasizes that balancing performance against practical limits such as fabrication methods, cost, inspection, contamination control, and service environment remains a major challenge. Its overall conclusion is that many promising materials exist, but their usefulness depends on application-specific tradeoffs and on closer integration of material selection with design and manufacturing, with some systems judged to be more valuable targets for development than others.

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Figure 4 shows an example of a TI matrix composite (TMC) cross section.
Figure 4. Cross-Section Micrograph of a Ti Matrix Composite. Small, dark centers
of fibers are C monofilament substrates for deposition of SiC (light micrograph).
Materia l system: Matrix alloy - Ti-6242; Fiber - SiC about 5.6-mil-diameter SCS-6
Table 2 shows that the strength and stiffness properties of TMCs can exceed those of
the Ti matrix (or other a.+13 Ti alloys) by more than a factor of two with no increase in
density. So why are TMCs not in widespread use? The foremost reason is cost. Another
reason is the availability of SiC fiber for TMCs.
• During the 1990s, when the U.S. government (mainly DoD) was interested in and
provided development money for TMC R&D, t he most attractive reinforcing fiber was
SCS-6™, which was produced exclusively by Textron Specialty Materials (TSM) in
Lowell, MA.
• Unfortunately (at least in hindsight), TSM made a business decision not to sell fiber
and to instead forward-integrate and sell TMC components or finished TMC mill
products. This decision stemmed in part from TSM's negative business experience
with development of B-based fiber (Boro-SiC™) for first-generation TMCs.
• Prior to making this business decision, TSM did not develop sufficient TMC
manufacturing expertise to properly position itself as a producer of TMC products
with consistent properties.
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