Variances in theMeasurement of Ceramic Powder Properties

Abstract

Variances in the measurement of properties used to characterize ceramic powders are discussed in the context of the International Energy Agency's study, Annex II, Subtask 2, which includes chemical and physical measurements for five powders: two grades of silicon nitride, and one grade each of silicon carbide, silicon, and zirconia. The analysis presented here includes results for 39 properties reported by 25 laboratories using approximately 700 samples of the powders. Measurement uncertainties are discussed in the contexts of measurement variations within given laboratories (within-laboratory variance, sometimes called re-peatability), among different laboratories (between-laboratory variance, also called reproducibility), and among different mea-surement techniques (between-methods variance). The analysis shows that the be-tween-laboratory variance tends to be sig-nificantly greater than either the within-lab-oratory or the between-methods variances. The implication of this result is that the most important improvements in powder characterization measurements may be achieved through the standardization of the measurement methodologies.