ISSN:
1089-7623
Source:
AIP Digital Archive
Topics:
Physics
,
Electrical Engineering, Measurement and Control Technology
Notes:
Equilibrium decomposition pressures of many inorganic substances are difficult to determine using static equilibration methods, particularly at low temperatures where the equilibration time may be excessively long. Additionally, in static experiments metastable conditions can develop so that true equilibrium is not reached. To overcome these problems, the author has previously used a cyclic thermogravimetric technique to study the decomposition of several carbonates. This dynamic method involved cycling the furnace temperature while a gas stream with a fixed partial pressure of CO2 flowed over the sample. This procedure allowed equilibrium to be established rapidly; thus, reliable data were obtained in a much shorter period of time than had been required previously. An alternative cyclic technique for carbonates has now been developed, where the CO2 partial pressure of the flowing gas stream is cycled at a fixed temperature. The cyclic CO2 pressure method has several advantages over other techniques. The decomposition pressure of calcium carbonate as a function of temperature, which is well known, has been measured to test the viability of the cyclic CO2 pressure technique. The results agree well with the previous thermal cycling data and with currently accepted literature values. A detailed description of the cyclic control of the flowing gas stream using a Rockwell AIM-65 microprocessor appears in this article.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.1139749