UNCERTAINTY OF THE MEASUREMENT OF DC CONDUCTIVITY OF CERAMICS AT ELEVATED TEMPERATURES
Igor Štubňa – Viera Trnovcová – Libor Vozár – Štefan Csáki
The electrical DC conductivity is measured at room and elevated temperatures on green ceramic samples prepared from kaolin. The used arrangement of the sample, with two platinum wire electrodes inserted in the kaolin prism, is suitable for measurements of temperature dependences of the DC conductivity from 20°C to 1100°C in the air. The uncertainty analysis taking into account thermal expansion of the sample, homogeneity of temperature field, measurement regime, corrosion of the electrodes, and overlapping of the electrodes is done for 1000°C. Uncertainties connected with current and voltage measurements and uncertainties connected with used instruments are also considered. The sum of the all partial uncertainties gives an expanded uncertainty of the conductivity measurement. The uncertainty varies with a temperature and reaches the value of ~ 6.5 % at 1000°C.
Keywords: conductivity, temperature dependences of conductivity, uncertainty