Advanced High Temperature Thermal Analysis Apparatus Employing Derivative and Differential Techniques

Abstract

The techniques of thermal analysis, derivative thermal analysis, differential thermal analysis, and a new function, thermal derivative thermal analysis (temperature vs derivative of temperature curves), are combined in this apparatus. High sensitivity is available for detecting small heat effects (less than 0.2 cal/sec) produced by rapid phase transitions in cooling or heating samples, and accurately determining their temperatures. Light from the incandescent sample s is sensed by photoconductive diodes. (Thermocouples with suitable amplifiers may be used for lower temperature studies.) The diode currents after processing are displayed on a dual‐trace storage oscilloscope. The temperatures of the samples, which are heated indirectly by induced radio frequency currents, are measured using a calibrated beam splitter and optical pyrometer. A description of a light source used to demonstrate the various displays by simulating thermal arrests in the cooling or heating curve of an incandescent sample is included. Illustrations are given for typical thermal analysis displays in the Nb‐C, Ti‐C, and V‐C systems.