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APPARATUS FOR INVESTIGATING PHASE TRANSFORMATIONS AND REACTIONS IN SUBSTANCES UNDER QUASI-ISOTHERMAL CONDITIONS
APPARATUS FOR INVESTIGATING PHASE TRANSFORMATIONS AND REACTIONS IN SUBSTANCES UNDER QUASI-ISOTHERMAL CONDITIONS
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机译：准等温条件下物质的相变和反应研究的装置
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1391121 Differential thermal analysis MAGYAR OPTIKAI MUVEK 5 May 1972 [17 Aug 1971] 21003/72 Heading G1N [Also in Division G3] In an apparatus for the investigation of phase transformations and reactions of a material by differential thermal analysis, a material sample 1, Fig. 2 is placed in crucible 2 within an electric furnace 15, while an inert reference material 3 which does not suffer chemical or physical changes when heated, is placed in a crucible 4. The temperatures of the sample and reference materials are sensed by thermocouples 6, 5 respectively connected in series opposition in a bridge. A mirror galvanometer 9 is deflected by an amount depending upon the difference in temperatures sensed and activates either a photo-cell 11 or 12 by reflecting light from a light source 10 depending upon which material has the higher temperature. This causes a switching device 13 and a programme regulator 14 to control the heating current of the furnace accordingly. Thereby the temperature of the sample can be rapidly increased as long as no change takes place in the sample such as phase transformation or reaction in its crystal structure, in which event quasi-isothermal conditions are ensured by the control arrangement. The temperature of the sample 1 is measured by a galvonometer 8 and recorded on a photosensitive strip 17. When a phase transformation occurs (point b in curve TA) the temperature of the sample stops increasing and remains steady until point c, and a finite differential temperature obtains which is used as described above to control the furnace. The apparatus thus controls the rate of phase transformation, and this rate may be reduced to a minimum so that phase transformations occur at practically isothermal and thus equilibrium conditions.
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