Documents / Official release
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.
UNCLASSIFIED//P'O" OP'P'lf!IAL YSIE Ql'.L¥ alloys' superior thermal fatigue resistance gives them great potential for use in TPS; thus, it would be appropriate to revisit this class of alloy after addressing its past problems. Many of the Ni-base alloys are fusion weldable, but the higher strength grades are prone to cracking without special precautions such as preheating the work piece. Most alloys capable of being processed into sheet also can be processed to create a fine grained structure. The fine-grained material can be superplastically formed, which is potentially of very important benefit to making light-gauge, load-bearing structures and TPS components. Finally, although almost all Ni-base alloys contain Cr and Al, both of which improve oxidation resistance by forming a stable, protective scale, this scale begins to lose its effectiveness above about 1,000 °Celsius. A number of effective environmental coatings have been developed by the gas turbine industry for Ni-base alloys. The only concern or unknown for application in a reusable 550 vehicle is the durability of these coatings under very high mass flow conditions, such as during reentry. Refractory Meta I Alloys Refractory metal alloys were discussed briefly earlier in connection with the DynaSoar project. Subsequent to this, there has been limited systematic interest in designing aerospace structures that incorporate refractory metal alloys. There has been interest in using these alloys for high-temperature gas-cooled nuclear reactors, where the operating environment is benign and well controlled, but this has limited relevance to the current discussion of space vehicles required to withstand reentry into the earth's atmosphere. The attraction of refractory metals as a class is the high melting temperature of Mo, Nb, and Ta. Although alloys of these metallic elements exhibit "normal" temperature dependence of mechanical strength, 0.STm of Nb or Mo is still a higher temperature than Ni-base alloys can withstand. Of the three metals, Nb is by far the most attractive because of its lower density, lower elastic modulus, and better (but not good) oxidation resistance. The clear barrier to use of Nb alloys is their reactivity in air at high temperatures. There are coatings for these alloys, but at 1,250 °Celsius, a breach in the coating will cause immediate, catastrophic failure. A reasonable design practice for critical structure, such as the TPS, is to disallow use of any coated material if the material fails catastrophically when the coating is breached. If this practice were the norm, then refractory metal alloys would not be usable in the TPS or other critical hot structure in a reusable 550 vehicle. Ceramic Matrix Composites Ceramic matrix composites (CMCs) are attractive because they are much tougher than, but retain the high-temperature capability of, monolithic ceramics. CMCs' toughness is derived from the fibers used to reinforce the ceramic matrix. When a CMC is loaded in tension and the stress in the ceramic matrix reaches a critical value, microcracks develop. This stress level is known as the matrix microcrack stress. In a monolithic ceramic such as silicon carbide (SiC) or silicon nitride (Si3N4), microcracks would propagate rapidly, causing immediate failure. For this reason, monolithic ceramics are not suitable for tension-loaded applications. This characteristic is mitigated in CMCs by reinforcing the ceramic matrix with high-strength ceramic fibers, typically Al 2O3 or SiC, whose role is to bridge and arrest the cracks. Under continued loading, the fibers also 18 UNCLASSIFIED/ /FOA QFFICilAL WIiii QNLY
Not linked to a story yet.
Official release, from the pursue collection. The PDF is mirrored here; the original link is above. 27 pages are in the text index: search them above, or from the library's search.