BS ISO 19629:2018 pdf free

BS ISO 19629:2018 pdf free.Fine ceramics一Thermophysical properties of ceramic composites
The detector shall be either a quantum radiation detector, a thermocouple or any other means that does not disturb the measurement of the transient response of the specimen. It shall be capable of detecting changes of 0,05 K in the temperature of the test piece, with a linear response over the range of temperature change less than or equalto 5 K.
The choice of the detector depends primarily on both the temperature range in which the measurement is to be performed and the characteristic time of the sample. The first parameter sets the spectral range for which the detection sensitivity of the detector shall be maximum; the second parameter fixes its time constant.
Care shall be taken that the signal comes only from the central area of the back face, that is with a tolerance of 5 % of the diameter of the test specimen.
When used, thermocouples shall be of the separated junction type, the hot junction being the back face of the test piece. They shall be in accordance with EN 60584-1. Electrically non-conductive material shall be coated on the front face and on the rear face, with a thin coating of high thermal conductivity material in order to ensure accurate measurement of surface temperatures.
In order to minimize heat losses, the use of the thermocouples with wires of the smallest possible diameter is recommended.
The thermocouple type most often used is chromel-alumel for measurements from room temperature up to 1 100 K. Semi-conducting couples may also be used: Bi2Te3 from 90 K to 400 K and FeSi2 for temperatures up to 1 100 K. For temperatures over 1 100 K, a non-contact measurement technique is recommended.
The data acquisition system used may be analogue or digital. It shall be equipped with a means of recording the temperature change versus time (before, during and after the pulse) and the time origin.
These means shall be accurate to within 0,02 ms.
The size of the test specimens shall be fixed to meet the requirements for application of the chosen thermal model (for example like the one described in Annex A). Generally a disc of a diameter between 1 to 8mmisused.BS ISO 19629 pdf download.