Livermore Lab researchers have developed a method that combines additive manufacturing (AM) with an infill step to render a final component which is energetic. In this case, AM is first used to print a part of the system, and this material can either be inert or energetic on its own. A second material is subsequently added to the structure via a second technique such as casting, melt infiltration, a second AM step/process, or other deposition techniques. The result is a final energetic part with some desired safety and/or performance properties.
Chemicals and Materials Technologies
LLNL has developed a liquid-free method that increases the overall mechanical resistance of self-supported, carbon nanotube assemblies through nanoscale reinforcement by gas-phase deposition of a thermally cross-linkable polymer. Polymer-reinforcement increases the strength of CNT yarns after crosslinking. For example, a minimal amount (<200 nm) of poly-glycidyl metacrylate (PGMA) deposited on the yarn, is enough to increase its Young's modulus to values ≥20 GPa.
Free-standing sheets of preferentially aligned CNTs are manufactured by pulling from the edge of CNT arrays (or forests) produced by chemical vapor deposition. Yarns are produced by either inserting twist into pulled CNT sheets or by direct spinning (twisting while pulling) from forests (fig. 1A-B). Inter-nanotube…
LLNL researchers have developed a process and direct ink writing (DIW) inks for fabricating structured carbon aerogels. This approach gives control over channel size and geometries of organic and carbon aerogels. The 3D printed Resorcinol-Formaldehyde (RF) ink structures are activated to yield high surface area carbon aerogels.
LLNL researchers have developed a new method of separating copper nanowires from copper nanoparticles in a two-phase liquid system, within one step, within a few minutes and with excellent separation results.
LLNL's new method of separation is based on the unique observation that copper nanowires can cross the interface between water and a wide range of hydrophobic organic solvent (e.g. chloroform, hexane, toluene), while copper nanoparticles cannot.
LLNL researchers have developed a novel method of 3D printing regular microstructured architectures and subsequent complex macrostructures from additively manufactured bio-based composite thermoset shape memory polymer composite materials. This technology for 3D additively manufactured parts utilizes up to a 4 axis control DIW system for fabricating bio based thermally cured epoxy based SMP carbon nano-fiber composite parts.
Beyond the proposed printed micro-structure, LLNL inventors have also developed a manufacturing process which allows for not only multi-functional materials to be printed within a single part (printing materials that exhibit shape memory at different temperatures in specific areas of the part), but also the ability to reform macro-structures after a…
Conventional membranes tend to be two dimensional and with relatively large thickness, which limit the achievable permeability. The ultimate goal in membrane technologies is to combine high permeability and high selectivity. LLNL has developed a transformational 3D nm-thick membrane structure using ALD (atomic layer deposition) template approach. Our membrane structure has two independent bicontinuous pore systems separated by a nm-thick membrane. It dramatically increases the number of exchange sites and shortens the exchange pathway.
A ceramic HEPA filter designed to meet commercial and DOE requirements, as well as to minimize upgrade installation logistics for use in existing facilities. Current key performance requirements are described in DOE Standard 3020. The ceramic filter is designed to be nonflammable, corrosion resistant, and compatible with high temperatures and moisture. The ceramic filter will significantly increase filter life span and reduce life cycle costs, and open up new opportunities for overall process gas system and ventilation system design.
Dubbed the "LLNL Chemical Prism", the LLNL system has use wherever there is a need to separate components of a fluid. A few examples include:
- Chemical detection for known and previously unknown chemicals or substances
- Separation of biomolecules from a cellular extract
- Fractionation of a complex mixture of hydrocarbons
- Forensic analysis of chemical specimens
- Sample preparation prior to detection
- Environmental monitoring for or clean-up hazardous waste streams or illicit materials
- Purification of water, ultrapure solvents, high-value fine chemicals, industrial products and pharmaceuticals
- High throughput screening of novel compounds for biological activity, novel pharmaceuticals, and drug discovery…
LLNL has developed novel nanoporous carbon materials for the surface-stress-induced actuator technology. The morphology of these materials has been designed to combine high surface area and mechanical strength. The process allows for the fabrication of large monolithic pieces with low densities and high structural integrity. One actuation technology relies on electrochemically- induced changes of the surface stress, another on surface-chemistry-induced changes in surface stress. The latter allows for a direct conversion of chemical energy into a mechanical response.
LLNL is seeking industry partners to collaborate on quantum science and technology research and development in the following areas: quantum-coherent device physics, quantum materials, quantum–classical interfaces, computing and simulation, and sensing and detection.
The innovators have modified a epoxide-assisted sol-gel method to produce chlorine-free, monolithic REO aerogels in just a matter of hours. This method was demonstrated for the lanthanide series. An important factor in realizing the sol-gel transition with the nitrate precursor was the addition of a key ingredient and moderate heat.. These alcogels can then be dried and calcined to produce chlorine-free, low-density, high surface area REO aerogels covering the lanthanide elements. Nitrogen porosimetry showed pore sizes in mesopore range (<50 nm) and surface areas up to 150 m2/g for the uncalcined samples. Electron microscopy and XRD analysis show that the aerogels are crystalline after calcination, retaining particle sizes less than 20 nm at temperatures up to 1373K.
Livermore researchers have developed two novel TiCl4 based non-alkoxide sol-gel approaches for the synthesis of SiO2/TiO2 nanocomposite aerogels. Composite SiO2-TiO2 aerogels were obtained by epoxide-assisted gelation (EAG route) of TiCl4/DMF solution in the presence SiO2 aerogel particles. Additionally, the same TiCl4/DMF solution was employed to prepare SiO2@TiO2 aerogels by a facile one-step thermo-induced deposition (TID) of TiO2 on silica wet gels supports. After controlled drying in supercritical CO2, high surface area silica-titania aerogels were obtained as fine powders (EAG route) or as crack-free monoliths (TID route).
LLNL uses the additive manufacturing technique known as Electrophoretic Deposition to shape the source particle material into a finished magnet geometry. The source particle material is dispersed in a liquid so that the particles can move freely. Electric fields in the shape of the finished product then draw the particles to the desired location to form a “green body”, much like an unfired ceramic clay body. The green body is then sintered in an appropriate atmosphere to form a durable finished magnetic shape. That shape can then be magnetized to complete the process. The advantage in this method is two-fold from a design point of view. First there is a great deal of spatial geometric design flexibility, and second multiple materials can be used at different locations or as…
LLNL researchers have developed a new method of using silver nanowires for fabrication of ultralight conductive silver aerogel monoliths with predicable densities and excellent properties. Silver nanowire building blocks were prepared by polyol synthesis and purified by selective precipitation. Silver aerogels were produced by freeze-casting nanowire aqueous suspensions followed by thermal sintering to weld the nanowire junctions. As-prepared silver aerogels have unique anisotropic microporous structures with density precisely controlled by the nanowire concentration down to 4.8 mg/cm3 and electrical conductivity up to 51,000 S/m. Mechanical studies show AgNW aerogels exhibit "elastic stiffening" behavior with Young's modulus up to 16,800 Pa.
The LLNL method is based on freeze‐casting of aerosolized and pressurized metal salt solutions and subsequent thermal processing. This method generates both porous particles with sizes down to one micron and macroscopic monoliths with nanometer scale ligaments/struts. The material's density can be controlled during the freeze‐dried stage. Compared to conventional approaches, this method offers high yield, purity, and uniformity.
The LLNL charged particle deposition technology enables fabrication of material via the charged particle induced dissociation of precursor molecules. For the case electron beam induced fabrication of boron carbide, gaseous boron precursor is delivered to a substrate in a vacuum chamber. Surface adsorbed molecules are dissociated by a beam of electrons. Non-volatile fragments remain on the substrate leading to formation of a boron containing deposit.
The vacuum chamber and beam of charged particles are provided by a scanning electron/ion microscope or a large area flood irradiation system. The scanning electron microscope can provide a focused nanoscale beam of electrons or ions which is used to control the deposit feature size down to tens of nanometers. The beam can be…
By combining 3D printing and dealloying., researchers at LLNL have developed a method for fabricating metal foams with engineered hierarchical architectures consisting of pores at least 3 distinct length scales. LLNL’s method uses direct ink writing (DIW), a 3D printing technique for additive manufacturing to fabricate hierarchical nanoporous metal foams with deterministically controlled 3D multiscale porosities. Arbitrary shapes can be printed according to the application requirements. Moreover, the structure of three levels of porosity can be tuned independently which enables application specific multiscale architectures. In this method, DIW is used to extrude a gelbased metals mixture from a small nozzle into 3D periodic porous structures. The "ink" materials used for DIW are…
The novel LLNL technique uses electric fields to drive and control assembly. In the literature such methods have heretofore only formed disordered ensembles. This innovative method increases local nanocrystal concentration, initiating nucleation and growth into ordered superlattices. Nanocrystals remain solvated and mobile throughout the process, allowing fast fabrication of ordered superlattices. Nanocrystals covered by this approach include, but are not limited to, metal nanocrystals, semiconducting nanocrystals (quantum dots), and insulating nanocrystals, or a combination of those. Solvents used in this approach include, but are not limited to, hexane(s), toluene, and chloroform. This process can be easily scaled to cubic meter solution volume and square meter surface area.
LLNL researchers have developed an alternative route to protective breathable membranes called Second Skin technology, which has transformative potential for protective garments. These membranes are expected to be particularly effective in mitigating physiological burden.
For additional information see article in Advanced Materials “Ultrabreathable and Protective Membranes with Sub-5 nm Carbon Nanotube Pores”
LLNL researchers have conceived and performed studies relevant to the development of AM powders synthesized from asteroidal or meteoritical sources and the use of the powder as the feed source for additive manufacturing systems deployed in space. The method includes the steps of locating an asteroid or meteorite, making contact with the asteroid or meteorite, harvesting material from the asteroid or meteorite, and processing material from the asteroid or meteorite to produce high quality powder capable of being used for defect-free AM processing. This powder can then be used for additive manufacturing feed stock in space, and completing the parts or products by the additive manufacturing in space.
LLNL’s Polyelectrolyte Enabled Liftoff (PEEL) process makes changes to the substrate preparation, the holder and liftoff technique, and suggests modifications to the material itself to enable the preparation of large ultrathin free-standing films.
PEEL enables ultrathin films by chemically modifying the deposition substrate and decreasing the interfacial energy so that even thin films with small strain energies will delaminate.
PEEL employs robust, water-based, and self-optimizing surface chemistry to fabricate ultrathin films up to 100 cm2 or more in area.
LLNL’s PEEL technology is used to fabricate free-standing polymer films as thin as 10 nm that are capable of bearing loads ranging from milligrams to grams and deformations of up to 40%.
LLNL researchers have developed the hardware and chemistry to allow additive manufacturing of short carbon fibers in a thermoset polymer matrix which have a high degree of structural alignment over conventional cast or pressed short/chopped carbon fiber polymer composites.
The invention is based on the shear dispersal, alignment and concentration of fiber fraction within a resin system to yield a direct Ink Writable (DIW) system that can be utilized to 3D print complex architectures of highly aligned CF/epoxy resin composite with feature resolutions as low as 250um.
The short carbon fibers can be produced in a range of polymer matrices including bisphenol F epoxy resins and cyanate esters. The apparatus, systems, and methods provide additive manufacturing of a fiber…
Covalent cross-linking of graphene sheets is achieved by using carbon nanoparticles as cross-linker for randomly oriented single layered graphene oxide nanoplatelets. The use of a covalently integrated carbon binder makes these graphene aerogel foams mechanically very robust, and allows one to achieve high bulk electrical conductivities even at low densities.
3D printing involves the layer-by-layer deposition of one, or more, materials. The spatial placement of the material, if carefully controlled, can influence a desired static or dynamic property. The use of 3D printing to build complex and unique energetic components is at the center of LLNL’s architected energetic materials and structures effort. LLNL has developed several different methods for using 3D printing to create articles of energetic materials applicable to high explosives, propellants, and pyrotechnics. Methods being explored include direct printing of energetic materials as well as creating unique scaffold structures for integration with energetics.
LLNL’s polymer/carbon composites exhibit a strong temperature dependent conductivity response. Below a critical temperature such as the glass transition temperature ( Tg) or melting temperature, Tm of the polymeric network, the composite material is electrically insulating, having measured conductivities in the range of 1E-10 S cm-1. Upon being heated through a phase transition, the conductivity abruptly increases; this transition has been shown to be fully reversible and with a low hysteresis upon thermal cycling. Due to the nature of the switching behavior (semiconductor gating) the polymeric component of the composite is not limited to single polymer type and may be a variety of polymer systems including various elastomers, thermoplastics or thermosets, furthermore the critical…
LLNL has developed a method for electroplating nickel oxide/hydroxide electrode materials with very high energy- and power density onto a current collector. The method is especially suitable for coating porous current collectors with high surface areas.
LLNL has developed a new class of nitrogenous ligands for metals and their complexes chosen for their known propensity to chelate metal ions. Further chemical modifications of this scaffold were performed to furnish a novel series of ligands that are capable of coordinating different metal ions.
Nanomaterials that are emerging out of cutting edge nanotechnology research are a key component for an energy revolution. Carbon-based nanomaterials are ushering in the "new carbon age" with carbon nanotubes, nanoporous carbons, and graphene nanosheets that will prove necessary to provide sustainable energy applications that lessen our dependence on fossil fuels.
Carbon aerogels (CAs) are nanoporous carbons that comprise a particularly significant class of carbon nanomaterials for a variety of sustainable energy applications. CAs are specifically promising in that they possess a tunable three-dimensional hierarchical morphology with ultrafine cell size and an electrically conductive framework. They are available as macroscopic, centimeter-sized monolithic materials.
In collaboration with USDA, LLNL has developed and tested in vitro (or ex vivo) production of natural rubber polymer by using NLP-stabilized rubber transferase.
Self-Propagating High Temperature Synthesis
LLNL seeks partners interested in developing and commercializing any or all of these and additional processes for its project as fits the partner's business interest. Examples of novel processing and resultant materials are described below.
High Explosive Consolidation (HEC) is conducted in a unique facility in Georgia that permits the explosive consolidation of powders at temperatures up to 1000°C. The high pressures and rapid consolidation generated during the propagation of the explosive-generated shock wave permit new and unique materials to be formed. The materials can also have very fine, potentially nano-scale, structure. The high rates of compaction resist grain growth and structural coarsening during consolidation and thus nano-scale structures can be retained during…
To overcome limitations with cellular silicone foams, LLNL innovators have developed a new 3D energy absorbing material with tailored/engineered bulk-scale properties. The energy absorbing material has 3D patterned architectures specially designed for specific energy absorbing properties. The combination of LLNL's capabilities in advanced modeling and simulation and the additive manufacturing technique known as direct ink writing allowed LLNL researchers to design and control the material's compression properties with very small feature sizes. The fine control that direct ink writing provides to the manufacturing process further enables specialty properties where desired in the bulk material. Advantages include:
- Controlling directionally dependent properties,…
An LLNL and UCLA team has recently demonstrated a new compound material that can directly convert thermal energy to electrical energy. Basic research is required before this newly invented material can be produced in the form of a thin film and tested at high frequency. The team is interested in partnering with a company from basic research and development through production of a manufacturing prototype.
The nanosphere synthesis process works when a nanostructured substrate is heated above a critical temperature in the presence of a small amount of metal on the nanostructured surface. The metal acts as a particular type of catalyst for nanowire formation. It is periodically segregated within the nanowire in a thermodynamically well-defined process as nanowires grow. The result is periodically-spaced metal nanoparticles within an insulating nanowire. Dense arrays of nanowires can be formed in this way without lithography of any kind.
An invention at LLNL uses a mixture of solid and liquid dielectric media. This combination has properties that are an improvement over either separately. The solid phase, in the form of small pellets, inhibits fluid motion, which reduces leakage currents, while the liquid phase (dielectric oil) provides self-repair capabilities. Also, since the media is removable, the high voltage equipment can be serviced.