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1061; Report; December 1980.
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Library's review
ABSTRACT:
The decomposition of NaN03 and KN03 has been studied in air, argon, and vacuum with these experimental techniques: differential scanning calorimetry (DSC), chemical analysis, thermogravimetry (TG) and mass spectrometry (MS). Above 840 (.!., 10) and 820 (.!., 20) K, for NaN03 and KN03
Vaporization and decomposition of the nitrates occurred concurrently at 630 Kin addition to vaporization of the decomposition products, superoxide and peroxide. The intrinsic (noncondensible) decomposition products of NaN03 and KN03 are N2, NO and 02. Nitrogen and nitric oxide are the initial decomposition products and oxygen is a product that appears in increasing proportions as decomposition proceeds and at higher temperatures. The rates of weight loss in TG experiments were proportional to the surface area of the salt. In vacuum, the rates of weight loss were 0.12 and 0.17 mg-cm-2-mfn-l for NaN03 and KN03, respectively, at 740 K • The activation enthalpies for NaN03 and KN03 are, respectively, 36.6 and 34.9 kcal-mole-1 (+ 4.9 kcal-mole-1 for a 90% confidence limit) from 630 K to 750 Kin vacuum. The rates of weight loss in static air were approximately 1% of the rates of weight loss of the nitrates in vacuum.
Z. A. Munir, Dissertation Committee Chair
Material Science Division
Department of Mechanical Engineering
University of California, Davis
The decomposition of NaN03 and KN03 has been studied in air, argon, and vacuum with these experimental techniques: differential scanning calorimetry (DSC), chemical analysis, thermogravimetry (TG) and mass spectrometry (MS). Above 840 (.!., 10) and 820 (.!., 20) K, for NaN03 and KN03
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respectively, endothermic decomposition reactions were evident in DSC experiments. These decomposition reactions caused the alkalinity to increase and the amount of nitrite to increase in the nitrates. A statistical screening technique, in conjunction with chemical analysis, determined that of ten selected variables that cause decomposition, temperature was the most important variable. The presence of carbon dioxide or water vapor, high gas flow rates, and low purity of the salts also enhanced decomposition. Salt samples were decomposed in argon where it was observed that the nitrates decomposed almost entirely to nitrite as low as 624 K, a process which was enhanced by corrosion of the stainless steel containers that were used.Vaporization and decomposition of the nitrates occurred concurrently at 630 Kin addition to vaporization of the decomposition products, superoxide and peroxide. The intrinsic (noncondensible) decomposition products of NaN03 and KN03 are N2, NO and 02. Nitrogen and nitric oxide are the initial decomposition products and oxygen is a product that appears in increasing proportions as decomposition proceeds and at higher temperatures. The rates of weight loss in TG experiments were proportional to the surface area of the salt. In vacuum, the rates of weight loss were 0.12 and 0.17 mg-cm-2-mfn-l for NaN03 and KN03, respectively, at 740 K • The activation enthalpies for NaN03 and KN03 are, respectively, 36.6 and 34.9 kcal-mole-1 (+ 4.9 kcal-mole-1 for a 90% confidence limit) from 630 K to 750 Kin vacuum. The rates of weight loss in static air were approximately 1% of the rates of weight loss of the nitrates in vacuum.
Z. A. Munir, Dissertation Committee Chair
Material Science Division
Department of Mechanical Engineering
University of California, Davis
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