Abstract:
THE THERMAL DIFFUSIVITY AND SPECIFIC HEAT OF MATERIALS IN THIN SECTIONS IS MEASURED AT LOW AND MODERATE TEMPERATURES BY A TRANSIENT HEAT FLOW METHOD WHICH EMPLOYS A SAMPLE PROBE AND A DUAL CHAMBER VESSEL. A SMALL DIAMETER SAMPLE IS HELD ON THE PROBE, WHICH IS SUPPORTED IN THE UPPER CHAMBER. AFTER THE SAMPLE HAS BEEN EQUILIBRATED AT A CHOSEN TEMPERATURE, IT IS QUICKLY LOWERED, MECHANICALLY, THROUGH A TRAP INTO CONTACT WITH A LIQUID IN THE LOWER CHAMBER, WHICH IS ISOLATED FROM THE UPPER CHAMBER, AND WHICH IS MAINTAINED AT A DIFFERENT TEMPERATURE. THE LOWERING IS CONDUCTED IN SUCH A MANNER THAT ONLY THE UNDER OR NEAR SURFACE OF THE SPECIMEN IS BROUGHT IN CONTACT WITH THE LIQUID. THE TEMPERATURE-TIME HISTORY OF THE FAR SURFACE, OBTAINED FROM A THERMOCOUPLE ATTACHED TO THE CENTER OF THIS SURFACE, IS RECORDED ON AN OSCILLOSCOPE.