DD288759A5 - MIRROR FOR THERMOANALYTIC EXAMINATIONS - Google Patents

Abstract

The invention relates to closable crucible for preparative and thermoanalytical investigations, especially in the high temperature range. A Ubertiegel with lid takes an inner crucible, which is also lockable on. The crucibles consist of materials of the lowest reactivity compared to the sample carrier, sample and possible calibration substance. Preferably, pyrolytically coated graphite is used for the Ubertiegel, which receives a metallic calibration substance for temperature and sensitivity of the Meszanordnung. The closure is done via ground joint, Schraubverschlusz, Labyrinthverschlusz, or Schweiszen. It reduces evaporation losses from the sample, thus protecting the oven and sample tray. The drawing shows the example of a crucible according to the invention with a polished finish in the upper lever. {Thermal analysis; Differential thermal analysis; reactivity; Crucible; Verschlusz; Graphite; Calibration; Temperature; Melt; Sensitivity}

Description

For this 1 page drawing

Field of application of the invention

The invention relates to crucibles for thermoanalytical investigations. Crucibles according to the invention can be used to investigate preparative and differential-thermal analysis samples up to the highest temperatures (T greater than 2000 ° C.).

Characteristic of the known state of the art

Thermal analysis (thermogravimetry, differential thermal analysis) in the temperature range up to 2400 "C is calculated in

Eigenbauvorrichtungen (TRESVIATSKY et al., Neorg., Materialy [1971], 7, 1808-1818) and commercially distributed measuring instruments (company brochures NETZSCH, SETARAM)] carried out.

The manufacturers of the measuring instruments offer open crucibles for receiving the material to be examined. Open crucibles have the disadvantage that evaporation losses irreversibly change the sample and pollute the meter. Melt the to

crawling sample out of the crucibles, the crucible with the sample carrier stick and the

Destroy sample carrier. Even clean crucibles from the sample carrier similar material stick after prolonged exposure

under high temperature by diffusion welding on the sample carrier.

Evaporation losses and the overflow of melts are avoided if welded ampoules serve as a crucible and absorb the sample material. (TRESVIATSKY, DAUB, Diss. A. Bochum 1985, p. 31) When welding, the sample must be cooled so that it does not change as a result of the effect of heat before the measurement. This sets one for the ampoules

Minimum size ahead. The sealed ampoules are much larger and heavier than conventional crucibles, causing the

Sensitivity of the measuring device deteriorates. The ampoules are usually only used once.

Closed-top crucibles have been developed for quasi-isothermal quasi-isomeric experimental conditions for thermogravimetric analysis of overlaying reactions and pre-compression under conditions of equilibrium vapor pressure. Only one sample can be introduced.

(DE-OS 2206714; PAULIKet.al., Thermochimica Acta, 100 (1986) 23-59)

Measuring arrangements of the thermal analysis are usually to be calibrated by preliminary experiments with respect to temperature and sensitivity. To perform the calibration with little time, the sample and reference page of the

Measuring arrangement are each provided with a calibration substance in a measuring operation, or is provided in addition to the sample to be examined, the reference page with a characteristic heat-inducing substance.

The prerequisite is that the difference between the characteristic temperatures several times greater than the product of

Time constant of the measuring device and heating rate during the measurement process is. According to the prior art

are used idento crucible on sample and reference side.

Object of the invention

The aim of the invention is to provide a sealable sample crucible for thermoanalytical investigations, which reduces evaporation losses of the sample, which prevents sticking to the sample carrier by overcrowding melts and diffusion welding, allows multiple internal calibration of temperature and sensitivity in the measurement process.

-2- 288 759 Explanation of the life of the invention

The object of the invention is to develop a closable sample crucible for thermoanalytical investigations, the Evaporation losses of the sample world-wide prevented. The object is achieved in that the sample crucible from an outer sealable container

(Overtiegel) and one odor several inner, also vorschließbaren inserts (inner crucible), wherein the outer

Container can accommodate a suitable calibration substance, while in an internal Einsau the sample to be examined

located. The crucibles or crucible inserts consist of materials of the lowest reactivity to sample carriers,

Calibrant, sample. According to the invention pyrolytically coated graphite for the outer shell of the closable Sample container used. But it can also be made of high-melting-point metals or their alloys or of Ceramics exist. It absorbs the preferably metallic (Au, Ni, Ti, Pt, Ph u. A.) Calibration substances. But it is also derr « According to the invention, the calibration substance (eg Al ₂ O ₃ ) is in an inner crucible. The crucible on the Sample and Referenzseito the measuring arrangement are identical. One or more inner crucibles of the sample crucible, also made of pyrolytically coated graphite or other materials

(Metal, ceramics) take the sample, which is to be examined thermoanalytically. The choice of material pairing is made so that the sample and calibrant come in contact with the least reactive material.

The Innontiogel of the sample of the invention by the next inner crucible or a lid of the material

covered by the inner crucible.

The closure of the crucible with the lids is carried out according to the invention preferably via ground clearance, screw cap, Labyrinth seal. There is also the possibility of granting.

Thus, the sample crucible according to the invention can be weighed together without mixing it, so that the temperature scale can be calibrated at one or more points during the measuring process. This is advantageous if the thermocouples are subject to severe aging, such as the z. B. for WVRh Thermoelementebe'm use up to temperatures of 2400 ⁰ C is known.

Voileile of the invention are:

~ The inclusion of samples in the closed sample wings reduces evaporation losses. The composition of the sample changes less than in open pots. Repeat measurements on a sample become possible and useful. Furnace and sample carriers are less polluted, their service life increases.

- Easy removal of the reusable sample crucible from the sample carrier, rising, creeping melts are caught by the outer crucible and can not stick it to the sample carrier, which usually leads to the destruction of the sample carrier when loosened.

- saving additional calibration attempts. Greater accuracy of temperature and sensitivity calibration relative to the current measurement.

- Higher informative value from itself to the thermoanalytical investigation from the sample material subsequent chemical, phasenanalytischon etc. investigations, up to the execution of sintering tests on formed specimens with subsequent structure evaluation.

embodiment The invention will be explained in more detail in the following embodiment. The accompanying drawing shows a possible Embodiment of a sample crucible for thermoanalytical investigations. A sample crucible consists of an outer transom 1 and a lid 2. The transom 1 receives an inner crucible 3,

which is closed by a cover 4.

The Übertiegel 1 usually consists of a conical lower part and a cylindrical upper part, which together with the Cover 2 encloses, for example via ground clearance in the sample pot a volume as tightly closed. The Closure is made by lifting or / and turning the lid 2 relative to the Transom 1. The Transom 1 takes

an exclusively conical inner crucible 3.

Other embodiments of the sample crucible, such as hemispherical or cylindrical lower parts, other cover variants

and also several inner crucibles are possible.

Claims (6)

1. crucible for thermoanalytical investigations, characterized in that the sample crucible of an outer sealable container, the Ubertiegel (1) and one or mehreron inner,
also closable inner pans (3) to reduce evaporation losses of the sample
and in parallel receives a suitable calibration substance, sample and calibration substance are not mixed and the over- or Ir nentiegel (1) (3) consist of materials of the lowest reactivity with respect to sample or calibration substance. 2. crucible for thermoanalytical investigations according to claim 1, characterized in that the coming into direct contact with the sample carrier Transom (1) consists of pyrolytically coated graphite. 3. crucible for thermoanalytical investigations according to claim 2, characterized in that the transom (1) consists of refractory metals, their alloys or of ceramic. 4. crucible for thermoanalytical examinations according to claim 3., characterized in that the inner crucible (3) made of dam material of the crucible (1). 5. crucible for thermoanalytical investigations according to claim 4, characterized in that the inner crucible (3) made of a different material than the Transom seal (1). 6. crucible for thermoanalytical investigations according to claim 5, characterized in that the cover of the inner crucible (4) or the cover of the bolt (2) via ground-fitting,
Screw cap, Labyririte closure sealed or welded.