Title

PHASE DIAGRAM STUDIES OF NH₄NO₃-KNO₃ BINARY SYSTEM FOR AUTOMOTIVE AIR BAG APPLICATIONS

PHASE DIAGRAM STUDIES OF NH₄NO₃-KNO₃ BINARY SYSTEM FOR AUTOMOTIVE AIR BAG APPLICATIONS

Authorship

CHIEN, WENMING; CHANDRA, DHANESH; FRANKLIN, JENNIFER; RAWN, CLAUDIA J.; HELMY, ABDEL K.

CHIEN, WENMING

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CHANDRA, DHANESH

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FRANKLIN, JENNIFER

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RAWN, CLAUDIA J.

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HELMY, ABDEL K.

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DOI

10.5151/2594-5327-3091

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Abstract

The solid-state phase transitions in ammonium nitrate (NH₄NO₃) and potassium nitrate (KNO₃) solid solutions and the equilibrium NH₄NO₃-KNO₃ (AN-KN) phase diagram have been investigated by using the differential scanning calorimetry (DSC) and high temperature X-ray diffractometry. Samples of several different compositions were made for these analyses in a special “Dry Room” with very low humidity. The equilibrium 0–25% KNO₃ AN-KN phase diagram was also calculated by using the FactSage computer program. A single (AN III) phase region without any phase transitions between 293 to 373 K was observed for compositions between 5 to 20 wt% KNO₃ in NH₄NO₃ that is critical for the air bag gas generators. The higher temperature KNO₃ (KN I) phase has a wide stability range, from pure 100% KN to 20% KN solution. There is one eutectic and one peritectoid found in 0–25% AN-KN phase diagram. Two new solid-state phases were found in the mid-composition range of AN-KN solid solutions. Details of phase equilibria, lattice expansions during heating will be presented. Phase diagram calculations show a reasonable match of the phase boundaries.

The solid-state phase transitions in ammonium nitrate (NH₄NO₃) and potassium nitrate (KNO₃) solid solutions and the equilibrium NH₄NO₃-KNO₃ (AN-KN) phase diagram have been investigated by using the differential scanning calorimetry (DSC) and high temperature X-ray diffractometry. Samples of several different compositions were made for these analyses in a special “Dry Room” with very low humidity. The equilibrium 0–25% KNO₃ AN-KN phase diagram was also calculated by using the FactSage computer program. A single (AN III) phase region without any phase transitions between 293 to 373 K was observed for compositions between 5 to 20 wt% KNO₃ in NH₄NO₃ that is critical for the air bag gas generators. The higher temperature KNO₃ (KN I) phase has a wide stability range, from pure 100% KN to 20% KN solution. There is one eutectic and one peritectoid found in 0–25% AN-KN phase diagram. Two new solid-state phases were found in the mid-composition range of AN-KN solid solutions. Details of phase equilibria, lattice expansions during heating will be presented. Phase diagram calculations show a reasonable match of the phase boundaries.

Keywords

AN-KN Phase Diagram, DSC, XRD, ammonium nitrate, potassium nitrate

AN-KN Phase Diagram, DSC, XRD, ammonium nitrate, potassium nitrate