| 摘要 |
1,074,366. Thermal analysis apparatus. IMPERIAL CHEMICAL INDUSTRIES Ltd. Feb .17, 1966 [March 10, 1965], No. 10212/65. Heading G1N. A sample and a reference in a differential scanning calorimeter are heated differentially by means of focused radiation to maintain their temperatures equal. The sample and reference mounted in metal blocks 10, 11 are heated equally by means of a projection lamp (23) Figs. 1 and 2 (not shown) and the average temperature of the blocks is increased by increasing the current supplied to the lamp. A second projection lamp (35) is pivotally mounted on the opposite side of the blocks and is initially placed so that it heats both blocks equally. If the temperature of the sample or reference changes the temperature difference is sensed by a pair of thermocouples consisting of constantan wire 19 and copper wires 12, 13. The differential output is applied to a recording potentiometer 46, through a magnetic amplifier 45, the needle being connected to lamp (35) to rotate it and so maintain the temperatures equal. The average temperature of the blocks is indicated by the voltage between wires 38, 40 and is compared with a reference voltage at 39, the difference being used to control the current through main lamp (23). The reference voltage is varied to vary the heating. A rotatable stop (29) is placed between lamp (23) and the sample and reference for additional control of the heating. A modification is referred to in which the average temperature is measured by means of a separate thermojunction beneath blocks 10, 11. The blocks are covered by a glass dome (47) lined with copper foil and having two windows to admit the heating radiation. Instead of rotating the lamp (35) it is stated that the radiation therefrom may be differentially blocked. The power supplied to the sample or reference to keep the temperatures equal is indicative of the heat changes in the sample. The device is calibrated by means of a sample having a known transition energy or by placing a resistance in hole 22 in one block and passing a measured electrical pulse through it. |
