|Acquisition Program: ||PM Future Combat Systems Brigade Combat Team|| Objective: ||Exploit emerging nano-materials technologies to develop and optimize nanocomposites to result in multifunctional materials, such as lightweight structural materials with radio frequency-electromagnetic interference (RF/EMI) shielding.
|| Description: ||Nanocomposites, the integration of nanomaterials into metals, polymers and ceramics, are an area of intense interest to the Army for the design of next generation lightweight structures with enhanced properties and multifunctional capabilities. Lightweight structural systems can be realized through the development of composites having nanoscale reinforcement with the proper morphological control. Metal matrix composite systems such as aluminum or magnesium reinforced through carbon nanotube and/or other dispersoid inclusion is one area of interest. While the nano reinforcement offers enhanced properties as compared to their traditional counterparts, such composites can be engineered for multifunctionality. For example, the aforementioned metal matrix composite can be designed as a structural component with sufficient RF/EMI shielding for sensitive military applications including but not limited to, components for munitions housings/casings. Thus, the goal of this effort is to demonstrate novel nanocomposites designed preferably through the particulate route, with a high strength to weight ratio and RF/EMI shielding equivalent to or better than currently fielded materials in accordance with MIL-STD-461E and other appropriate standards.
|| ||PHASE I: Demonstrate that the impressive properties of nanoscale materials can be imparted to a macro-scale composite. Identify fillers and matrix materials, synthesis and processing technologies/parameters that result in lightweight structural nanocomposite materials suited to replace heavier materials systems that are currently in use. Quantify the effect of nanoscale particulate additives and design on the overall properties of the composite and demonstrate a tensile strength in excess of 600MPa at 5% elongation. Deliver candidate composites to the Army for property validation
|| ||PHASE II: (a) Scale up manufacturing processes for producing prototypes of at least 12" x 12" in size. (b) Modify as required (prototype geometry, composition, processing, etc.) and quantify mechanical properties with respect to the areal density of the nanocomposites. (c) Integrate the electromagnetic interference (EMI) shielding capability into the optimized hybrid nanocomposite structures.
|| ||PHASE III: Potential dual use applications include structural elements for munitions components, helicopters and aircraft, armored transports for counter-terrorism protection, vehicle protection, and Government buildings.
|| References: ||
1. R.Siegel, “Mechanical behavior of polymer and ceramic matrix nanocomposites”, Scripta Materialia, Volume 44, Issue 8, (2001) Pages 2061-2064
2. Srinivasa R. Bakshi, Virendra Singh, Kantesh Balani, D. Graham McCartney, Sudipta Seal, Arvind Agarwal, ”Carbon nanotube reinforced aluminum composite coating via cold spraying,”Surface & Coatings Technology 202 (2008) 5162–5169
3. Junichi Yuuki, Hansang Kwon, Akira Kawasaki, Akira Magario, Toru Noguchi, Junichi Beppu, Masayuki Seki “Fabrication of Carbon Nanotube Reinforced Aluminum Composite by Powder Extrusion Process,” Materials Science Forum (Volumes 534 - 536), Progress in Powder Metallurgy Pages 889-892 DOI 10.4028/www.scientific.net/MSF.534-536.889
4. Chan B. Mo, Seung I. Cha, Kyung T. Kim, Kyung H. Lee, Soon H. Hong “Fabrication of carbon nanotube reinforced alumina matrix nanocomposite by sol–gel process” Materials Science and Engineering A 395 (2005) 124–128
5. Katsuyoshi Kondoh, EL-Sayed Ayman Hamada, Hisashi Imai, Junko Umeda, Tyrone Jones, “Microstructures and mechanical responses of powder metallurgy non-combustive magnesium extruded alloy by rapid solidification process in mass production,” Materials and Design 31 (2010) 1540-1546|
|Keywords: ||light weight, structural, nanomaterials, composites; hierarchical, multi-functional; shielding |
Questions and Answers:
Q: (Our company) has a solid state optically transparent (tailorable for IR transparent) vacuum deposited inorganic material that is very flexible with 2.5 ohms per square that is at TRL 6 for ballistic armor. The technology is UV tolerant. Please let me know if this is of interest. Thank you
A: For the scope of this topic, this technology would not be of interest.
Q: Does carbon nanotube/ceramic composite fit this topic? Thanks.
A: Yes, but in addition to the strength requirement the bulk material must also have a high fracture toughness.
Q: Does a graphene nanoplatelet/polymer composite fit this topic or does interest focus on metal matrix composite systems?
A: A metal matrix would be preferred, however if the polymer based composite can achieve the yield tensile strength metric of 600MPa at 5% elongation it will be considered.
Q: 1. Would nanoparticle reinforced fiber composites fit this topic provided that they can satisfy the strength and fracture tougness requirements?
2. Is there a goal/threshold value for the fracture toughness?
A: 1: A reinforced fiber weave would not fit this topic. We would prefer the metal based system as the strength requirement comes from titanium alloys.
2: There is no specific threshold for the fracture toughness, but (for ceramic systems) we would like to overcome current problems with materials such as boron carbide - they can fracture if dropped and are only good for a single impact if shot.
Q: 1. For effective trade studies, can you please let us know what are the current heavier material systems that are in use?
2. Is the material you are seeking an isotropic composite or can it be orthtotropic? In other words, are the mechanical property requirements valid for all directions of a unidirectional requirement?
3. What specific sections of MIL-STD-461 need to be satisfied in the earlier Phase I efforts?
A: 1. Current materials are typically steels. We would like to compete with titanium and its alloys.
2. The mechanical properties must be valid for all directions.
3. The radiated emissions and radiated susceptibility sections will have to be considered but will be stressed more heavily in the Phase II.