SU1236286A1 - Crucible furnace for massthermometry measuring of specimens - Google Patents

Description

The invention relates to instrumentation, namely, devices for other physicochemical research of substances.

The purpose of the invention is to improve the measurement accuracy by reducing the effect of convective currents and the electrostatic effect on the sample and increasing the stability of temperature in the furnace.

FIG. 1 shows a diagram of the furnace design; in fig. 2 - reflector; in fig. 3 shows section A-A in FIG. 2; in fig. 4 shows a section BB in FIG. 2; in fig. 5 is a diagram of the movement of gas flows in the working chamber.

The crucible furnace consists of a housing 1 with a cooled lid 2, inside of which there are screens 3 surrounding the working chamber 4, with the main and additional heaters 5 and 6. Above the working chamber 4 there is a shield 7. In the working chamber 4 along the axis there is a reflector. The reflector is made in the form of coaxially installed along the river cone-shaped screens 8-10, forming cavities, which are sequentially communicating with each other. The bottom screen 8 has a blind base 11. And the screens 9 and 10 of the base are open. For example, screens 9 and 10 can be installed on screens 8 and 9 using supports 12 and 13, and screen 8 is mounted on a stand 14 in the working chamber 6. The reflector is made of a plate.

The convective flow reflector is grounded (not shown) and thus performs the additional functions of an electrostatic shield, protecting the sample from electrostatic interaction with the walls of the furnace chamber.

The furnace also contains a lifting / lowering mechanism 15, which allows the distance from the bottom of the working chamber to the sample under study 16 to be adjusted.

The device works as follows.

The test sample 16 on the thread 17 of the hanger is placed in the reflector, after which the working chamber 4 is closed by a shingle 7

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and a cooled lid 2. The change in mass of the sample 16 when heated is continuously recorded by means of a microbalance. The cold gas enters the furnace through the leakage between the lid 7 and the walls of the working chamber 1, reflects from the upper screen 10 of the reflector, flows down the hot wall and, heating up, rises into the gap formed by the screen 8 of the reflector and screen 9 (Fig. 5) . Impact of ascenders

Flows to sample 16 are prevented by the bottom screen 8 of the reflector. The interaction of the upflows with the cold gas flows into the reflector through the suspension opening eliminates the effect of these flows on the sample. The cold gas flows are partially reflected by the screen 9 of the reflector and exits into the holes in the screen 10. As a result, the swinging of the suspension thread is significantly reduced, which causes the sample mass to be normalized.

The furnace provides for measurements in an environment with different oxygen partial pressures (from Horn 1 atm and below) when the sample is heated to a temperature

  K. When heated in an oxygen environment to high temperatures, only platinum has the necessary corrosion resistance. The corrosion effect on the screen is intensified when the measurements are made on the samples, which are highly chemically active substances, for example, some oxides. In addition, in the range of these temperatures, the plate has a slight pressure of its own vapor. Therefore, platinum-1 1Y rolled steel with a thickness of 0.5-1 mm is selected as the material for the manufacture of reflector screens.

The use of the invention makes it possible, compared with the base object, to significantly reduce the fluctuations in the indications of changes in the mass of the sample arising from

of the listed hazard factors, and to increase the measurement accuracy for this sample, for a given measurement sensitivity from –12 µg to –2 µg.

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Claims (2)

1. Crucible furnace for thermomassometric measurements of samples, comprising a housing with a lid, a working chamber, heaters, screens surrounding the working chamber, and a mechanism for raising and lowering the housing, characterized in that, in order to increase the measurement accuracy by reducing the effects of convective flows and electrostatic impact on the sample, the furnace is equipped with a reflector located in the working chamber, made in the form of coaxially mounted tiered cone-shaped screens forming cavities that sequentially communicate They are interconnected, with the lower conical screen having a blind base, and the other conical screens being open, while the reflector is grounded. 2. The furnace according to π. 1, characterized in that the reflector is made of platinum. N3 oo 05 to □ o 05