Thermal-Property Analyzer: Principles and Material Testing Applications

A thermal-property analyzer measures thermal conductivity, thermal diffusivity, and specific heat capacity. It simulates defined heat-flow conditions to quantify heat conduction and heat storage for thermal design and management.

Transient hot-wire method A fine metal wire, commonly platinum, serves as both heater and temperature sensor in a liquid or powder. Constant-power heating produces a logarithmic temperature rise; the temperature-rise curve and heat-conduction equation are used to calculate thermal conductivity and thermal diffusivity. The method is completed in minutes and does not require a strict specimen shape.

Laser flash method A thin solid specimen is heated on its front face by a laser or xenon pulse, while an infrared detector records rear-face temperature versus time. The half-rise time and specimen thickness give thermal diffusivity; density and specific heat capacity allow thermal conductivity to be derived.

Guarded hot plate and heat flow meter methods A flat specimen is placed between heated and cooled plates to establish one-dimensional steady heat flow. The guarded hot plate method calculates conductivity from heating power and temperature difference. A heat flow meter uses a calibrated heat-flow sensor and is suited to rapid testing of materials with low or medium conductivity.

Applications include thermal management of battery electrodes, separators, and electrolytes; thermal protection materials for spacecraft; chip-package materials, thermal grease, and heat-spreading substrates; building insulation, concrete, glass, and aerogels; and heat-transfer studies of metals and alloys during casting, welding, and heat treatment. Selection depends on temperature range, specimen state, conductivity range, accuracy, and specimen geometry. Solid specimens may require a standard flat form, with surface flatness and parallelism controlled to limit contact resistance. High-temperature tests require compatible expansion of the specimen and sensor. Reference materials are used for periodic calibration.