PRODUCTION AND COATING OF PURE BORON POWDERS

A NEW PROCESS IS PROPOSED TO SYNTHESIZE PURE SPHERICAL BORONPOWDERS COATED WITH EITHER TITANIUM OR ZIRCONIUM FOR USE IN ENERGETIC PROPELLANTS AND EXPLOSIVES. THE PROCESS IS BASED ON A PROCESS PREVIOUSLY DEVELOPED BY AERO-CHEM TO PRODUCE PHOTOVOLTAIC SILICON. IT INVOLVES THE REACTION OF VAPOR PHASE SODIUM WITH BORON TRICHLORIDE AND TITANIUM (OR ZIRCONIUM) CHLORIDE AND EXPANSION OF THE PRODUCTS T THROUGH A SUPERSONIC NOZZLE TO PRODUCE THE DESIRED PRODUCT WITH PARTICLE DIAMETERS IN THE RANGE OF 0.5 TO 50 MICRONS. THE METAL COATING IS REQUIRED TO PREVENT OXIDE BUILDUP ON THE BORON SURFACE DURING HANDLING AND IN THE EARLY STAGES OFCOMBUSTION. THE COATING WILL BE APPLIED PRIOR TO EXPOSUREO OF THE NEWLY FORMED BORON PARTICLE TO AMBIENT AIR AND THE COATING THICKNESS WILL BE LIMITED SO THAT THE COMBUSTION ENERGY IS NOT REDUCED BY MORE THAN 10% OF THAT FROM PURE BORON. THE MAJOR RESEARCH PROBLEMS TO BE SOLVED INVOLVE DEFINING THE APPROPRIATE OPERATING CONDITIONS TO PRODUCED COATED BORON PARTICLES AND THE COLLECTION OF THE FINE COATEDPARTICLES FROM HOT SODIUM CHLORIDE VAPOR.