Method of restricting propellant grains

Claim 1

IN A METHOD OF RESTRICTING A GRAIN OF SOLID ROCKET PROPELLANT COMPRISING 50 TO 90 PARTS BY WEIGHT OF A SOLID INORGANIC OXIDIZING SALT SELECTED FROM THE GROUP CONSISTING OF THE AMMONIUM, ALKALI METAL, AND ALKALINE EARTH METAL SALTS OF NITRIC, PERCHLORIC, AND CHLORIC ACIDS AND 5 TO 50 PARTS BY WEIGHT OF A BINDER COMPRISING A RUBBERY COPOLYMER OF A VINYL SUBSTITUTED HETEROCYCLIC NITROGEN BASE AND A CONJUGATED DIENE, WHEREIN CERTAIN SURFACES OF SAID GRAIN ARE RESTRRICTED BY ADHESIVELY BONDING RUBBERY RESTRICTING MATERIAL COMPRISING SAID COPOLYMER TO SAID SURFACES, THE IMPROVEMENT COMPRISING APPLYING TO SAID SURFACES A THIN LAYER OF AN AQUEOUS SOLUTION OF 1.5 TO 25 WEIGHT PERCENT OF A WATER SOLUBLE CHROMIUM COMPOUND, AND THEN BONDING SAID RESTRICTING MATERIAL TO THE THUS TREATED SURFACES, SAID CHROMIUM COMPOUND BEING SELECTED FROM THE GROUP CONSISTING OF CHROMIC AACID, CHROME NITRATE, CHROMIC SULFATE, CHROMOUS CHLORIDE, AMMONIUM DICHROMATE, POTASSIUM DICHROMATE, SODIUM CHROMATE, AND SODIUM DICHROMATE.