Uncertainty in the Determination of Young's Modulus of Ceramics Using the Impulse Excitation Technique at Elevated Temperatures

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Abstract
In this paper we describe the construction of a laboratory-made apparatus for the dynamical thermomechanical analysis (D-TMA) based on an impulse excitation technique (IET) and estimate the uncertainty of the measurement of Young's modulus of an unfired ceramic sample. The sample was measured during heating up to 1100 °C with a rate of 5 °C/min. Thermodilatometry and thermogravimetry were performed to determine the actual dimensions and mass of the sample in the same temperature regime. We assessed the influence of the repeatability of the directly measured values and the accuracy of the used measurers. We also took into account the inhomogeneity of the temperature field, sample fixing, estimation of Poisson's ratio and data processing. We found that 1) the highest part of the uncertainty comes from measuring the sides of the sample cross-section, 2) the sum of the uncertainties originating from heating the sample is comparable to the sum of the uncertainties at room temperature, 3) a maximal relative expanded uncertainty of Young's modulus is ∼2.6%.