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Lexington, MA, United States

Grant
Agency: Department of Defense | Branch: Air Force | Program: SBIR | Phase: Phase I | Award Amount: 70.95K | Year: 1991

N/A


Grant
Agency: Department of Defense | Branch: Army | Program: SBIR | Phase: Phase I | Award Amount: 49.50K | Year: 1992

SUPERCRITICAL FLUID NUCLEATION (SFN) IS PROPOSED AS THE MECHANISM FOR AN INNOVATIVE, IMPROVED METHOD FOR THE DISSEMINATION OF ULTRA-FINE PARTICLES. THE CONCEPT, AS APPLIED TO THE STATED TOPIC, INVOLVES THE RAPID EXPANSION OF A SOLUTION OF RIOT CONTROL AGENTS IN SUPERCRITICAL OR NEAR CRITICAL CARBON DIOXIDE FROM A SMALL CANISTER TO PRODUCE A FINE AEROSOL OF SOLID PARTICLES WHOSE SIZE CAN BE CONTROLLED BY EXPANSION CONDITIONS. SFN HAS BEEN DEMONSTRATED PREVIOUSLY FOR ITS ABILITY TO PRODUCE PREDICTABLE PARTICLE SIZES RANGING FROM SUBMICRON TO TENS OF MICRONS AND IS CURRENTLY UNDER EVLAUATION AS A MEANS OF PROVIDING A SUBMICRON MONODISPERSED PARTICLE GENERATED FOR LASER DOPPLER VELOCIMETRY. EXPLOITING SFN TECHNOLOGY AS A MEANS OF DISPERSING RIOT CONTROL AGENTS HAS A NUMBER OF POTENTIAL ADVANTAGES. FIRST, SUBMICRON PARTICLES, WHICH HAVE BENEFICIAL ADSORPTION AND TRANSPORT PROPERTIES, CAN BE PRODUCED. SECONDLY, CARBON DIOXIDE IS NON-TOXIC AND INFLAMMABLE AND BECAUSE GAS EXPANSION IS THE MECHANISM FOR PARTICLE RELEASE, PYROTECHNIC MATERIAL IS ELIMINATED. FINALLY, BECAUSE THE CONCEPT UTILIZES A SOLUTION OF RIOT CONTROL AGENTS IN CARBON DIOXIDE THE PRODUCTION, HANDLING, AND PACKAGING OF NOXIOUS FINE PARTICLES IS ELIMINATED.


Grant
Agency: Department of Defense | Branch: Air Force | Program: SBIR | Phase: Phase I | Award Amount: 70.95K | Year: 1992

THE COATING OF CARBON FIBERS WITH SILICON CARBIDE OFFERS ENHANCED OXIDATION RESISTANCE FOR CARBON/CARBON COMPOSITES. RESEARCH TO FORM A THIN, UNIFORM, COHERENT LAYER ON FIBERS IN A TOW, TAPE, OR 3-D PREFORM IS DESCRIBED. THE RESEARCH INVOLVES THE USE OF AN ADVANCED POLYCARBOSILANE POLYMER WHICH CAN BE CONVERTED TO SILICON CARBIDE. SUPERCRITICAL FLUIDS WILL BE USED TO DISSOLVE THE PRECURSOR POLYMER. A SUPERCRITICAL SOLUTION, BECASUE OF ITS ADVANTAGEOUS TRANSPORT AND SURFACE TENSION PROPERTIES, CAN BE PENETRATE MICROCHANNELS SUCH AS THOSE IN A TIGHTLY PACKED TOW, TAPE, OR 3-D PREFORM. DEPOSITION CONDITIONS TO PRODUCE THE THIN COATING WILL BE DEVELOPED. AFTER COATING, THE POLYMER WILL BE CROSS-LINKED AND PYROLYZED TO SILICON CARBIDE, AND OXIDATION RESISTANCE OF COATED CARBON FIBERS OR PREFORMS WILL BE MEASURED AND COMPARED TO UNCOATED CARBON FIBERS OR PREFORMS. AS A MEANS OF ASSESSING THE VALUE OF THE PHASE II EFFORT, AND ECONOMIC VIABILITY EVALUATION OF THE PROCESS FOR IMPROVED COATED CARBON FIBERS WILL BE MADE ON THE PHASE I PROGRAM.


Grant
Agency: Department of Defense | Branch: Missile Defense Agency | Program: SBIR | Phase: Phase I | Award Amount: 70.95K | Year: 1992

Ceramic composites of silicon carbide fibers in a silicon carbide matrix are currently produced via CVD infiltration (CVI), but the requisite high temperature for CVI can partially degrade the fibers. Infiltrating a SiC precursor polymer into a fiber preform and subsequently converting the polymer at low temperature (


Grant
Agency: Department of Defense | Branch: Army | Program: SBIR | Phase: Phase I | Award Amount: 69.11K | Year: 1996

Research to find supercritical fluid conditions capable of supporting polymerization of hexachlorocyclophosphazene trimer to high molecular weight poly (dichlorophophazene) is proposed. The dichloro polymer is the key intermediate in production steps that lead to a class of polymers having useful engineered applications, often where extremes of temperature and environment exist. A supercritical polymerization process could eliminate the hazards, handling, environmental concerns, and waste disposal costs associated with the current solvent-intensive polyphosphazene processes. The unique extraction and separation properties of supercritical fluids will be exploited to produce poly (dichlorophosphazene) free of contaminants and at a molecular weight useful for further modification. This proposal addresses issues related to solubilizing high molecular weight intermediate and promoting high yield polymerization in the supercritical medium. The cost benefits associated with supercritical fluid polymerization will be evaluated by carrying out an economic viability analysis of the process.

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