Thermobalance Honda

Fig. 2. Comparison of the classical Honda thermobalance with present, frequently used equipment...

The historical aspects ofTG have been discussed by Duval (3-5), Wend-Iandt (7), Keattch (23), and others (107-109). Perhaps thejirst thermobalance was that described by Nernst and Riesenfeld (I20X whp used a Nernst quartz torsion microbalance. equipped wit an electric furnace, to study the mass-loss on heating of Iceland spar. opal, zirconia, and other minerals. The Japanese Honda was apparently the first to use the term ihermobalance for an instrument he described in 1915 (9). The French school of thermo-gravimetry began with Urbain in 1912 when he modified two-pan analytical balance into a cril e thermobalance (24). This was followed by the work of Guichard (1923) (10), Vallet (1936), Chevenard (1936), Duval (1950), and many others.The first commercial thermobalance in the United States, which prompted funner work in TG. was that described by Mauer (31) in 1954,... 

The first thermobalance was probably the instrument described by Honda (30) in 1915. This instrument, as shown in Figure 3.18, consisted of a balance with a quartz beam. The sample was placed in a porcelain or magnesia crucible, G, which was suspended in an electrically heated furnace, J. Attached to the opposite end of the balance beam was a thin steel wire helix, E, which was immersed in oil contained in a Dewar flask, H. The Dewar-flask-helix assembly was adjusted by a screw mechanism to maintain the balance beam in a null position. A rather low heating rate was employed, since it took 10-14 hours to attain a temperature of 1000°C. However. Honda used a quasi-isothermal heating cycle in that during a mass-loss transition the furnace temperature was maintained at a constant temperature until the transition was completed. This procedure alone sometimes required 1-4 hours. Convection currents were evident above 300°C, as might be expected from the furnace sample arrangement. A sample mass of about 0.6 g was normally employed. 

The work of Honda did indeed lay the foundation for practically all of the future work in thermogravimetry. His thermobalance enabled the investiga-... 

Numerous other Japanese workers modified the Honda thermobalance and also developed new instruments. The results of their studies have been summarized in a monograph by Saito 19). 

Honda [42, 43] laid the broad foundations of modern thermogravimetry, introducing the thermobalance International Union of Pure and Applied Chemistry (lUPAC) was established The first commercial thermogravimeter was produced [35]... 

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