Application De L’ultrason A L’étude De L’homogénéité Des Briques Réfractaires

The quality of refractory bricks such as their ability to resist to thermal shocks essentially depends on the homogeneity of their structure. The imperfections observed in the structure of some refractory bricks arise from the mode of their preparation. Thus, the homogeneity of bricks manually elaborated with refractory clays and sintered at 1280°C was studied. The speed of ultrasounds in different areas of the bricks was measured with an ultrasound auscultation device. The results point out the speeds of ultrasounds may vary from one zone to another revealing heterogeneities into some bricks. This technique allows showing the distribution of possible heterogeneities in these materials

Experimental setup for the measurement of the electrical resistivity and thermopower of thin films and bulk materials

An experimental setup was developed for the simultaneous measurements of the electrical resistivity and the thermopower in the temperature range going from 77 up to 330 K. The system combines accuracy, rapidity, few efforts for the sample mounting, and is fully automated. Pressure contacts are used for contacting the thermocouples to the sample and the sample to the heat sink, making possible the measurement of both thin films and bulk materials with a great flexibility on their geometrical dimensions. Tests of the system have been made on a 99.98% pure Ni bulk sample and on PbTe/BaF2 thin films for illustration