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Iron Oxide Determination by X-Ray Fluorescence for In-Process Control of Solid Propellant and Premixes

Published online by Cambridge University Press:  06 March 2019

Reuel E. Lamborn
Affiliation:
Thiokol Chemical Corporation Brigham City, Utah
Foster J. Sorenson
Affiliation:
Thiokol Chemical Corporation Brigham City, Utah
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Abstract

Finely divided iron oxide is used as a burning-rate catalyst in several solid rocket propellants. The concentration is critical and must be accurately determined as a quality control point before the propeltant is cast in the motor case and cured, in addition to the iron oxide, the propellant used for ignition of the Air Force Minuteman first stage contains a polymeric binder system, a solid oxidizer, and a metal powder. This composition makes it difficult to determine accurately the iron content by wet methods in the time available daring the propellant processing cycle. The use of X-ray fluorescence has been investigated as a means of satisfying the analysis time requirements while meeting the prescribed accuracy of ±1% of the amount of iron oxide present. Procedures for preparing test specimens have been developed and instrument operation conditions chosen which yield satisfactory precision. When ten specimens from each of three premixes were analyzed for iron content, the observed within-mix mean relative standard deviation was 0.28%; for propellant analyzed under the same conditions, the mean relative standard deviation was 0.35%. Factors affecting mix-to-mix accuracy, such as particle size and shape and interelement absorption and enhancement effects, have been investigated. Accuracy is adequate for in-process control of the iron oxide level in the premix, but further work is required before satisfactory control of propellant is achieved.

Type
Research Article
Copyright
Copyright © International Centre for Diffraction Data 1962

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References

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