TCT 426

Thermal Conductivity Tester: furnace/hot-wire method

Absolute determination of the thermal conductivity of ceramic materials in accordance with ISO 8894-1 and ISO 8894-2

Thermal conductivity and thermal diffusivity are the most important thermophysical parameters for characterization of the thermal transport properties of a material or component.
The hot-wire method is an absolute method for direct determination of the thermal conductivity, based on the measurement of the temperature increase of a linear heat source/hot wire (cross-wire technique, according to ISO 8894-1) or at a specific distance from a linear heat source (parallel-wire technique, according to ISO 8894-2).

The hot wire and thermocouple are embedded between two test pieces, which make up the actual test assembly. The time-dependent temperature increase after the heating current is switched on is a measure of the thermal conductivity of the material being tested.

Another variation, the so-called "Platinum Resistance Thermometer Technique" or "T® Technique", is described in ASTM-C 1113. Here an integral temperature measurement is carried out over the entire length of the hot wire; i.e. the hot wire is both heat source and temperature sensor at the same time.

The TCT 426 thermal conductivity tester enables the use of all three of the methods described in easily interchangeable, pre-wired measuring frames.

Key Technical Data

(subject to change)

  • Temperature range
    in accordance with ISO 8894-1, ISO 8894-2 from RT to 1250°C (higher temperatures up to 1500°C are possible depending on the material)
  • Chamber-hood furnace
    with 12 Super-Kanthal heating elements
  • Heating and cooling rates:
    0,01 K/min to 5 K/min
  • Atmospheres:
    air, static
  • Hot-wire capacity:
    0.1 to 50 W (continuously adjustable power in 2 zones)
  • Measurement of the temperature increase with differential thermocouples
  • Test piece dimensions:
    250 mm x 125 mm x 75 mm
    (2 test pieces together make up one test assembly)
  • Measuring frame
    for cross-wire method and parallel-wire method
  • Measuring frame
    for T® technique (optional)


From the year 2006 onwards, the TCT 426 runs under Proteus® Software on Windows®. The Proteus® Software includes everything you need to carry out a measurement and evaluate the resulting data. Through the combination of easy-to-understand menus and automated routines, a tool has been created that is extremely user-friendly and, at the same time, allows sophisticated analysis. The Proteus® Software is licensed with the instrument and can of course be installed on other computer systems.

TCT features:

  • Monitoring of temperature stability in isothermal steps
  • Start of hot-wire current (repeat measurements automatically selectable)
  • Measurement of the time-dependent temperature increase in the test assembly
  • Designation of the evaluation range in the temperature increase curve
  • Calculation of the thermal conductivity according to the relevant evaluation formula
  • Results in tabular and graphic format
  • Integrated databank

You can use the following software with this product:

Proteus® Software


  • Measuring frame for cross-wire method
  • Measuring frame for parallel-wire method
  • Measuring frame for T® technique
  • Muffle case for measurements on dielectric powders or granular materials
  • Muffle case for measurements on carbonaceous materials
  • Machines for test piece preparation




Application brochure: "Material Characterization, Phase Changes, Thermal Conductivity", 24 pages

Application literature


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