The transient heat source method thermal conductivity analyzer mainly uses a planar probe, and its core component is a continuous double helix structure thin film formed by etching a conductive alloy (such as nickel alloy) with a linear temperature resistance coefficient relationship. The outer layer is covered with a double-layer Kapton or other insulating material as a protective layer. This design allows the probe to serve as both a heat source and a temperature sensor; During testing, the current passes through the probe and generates heat, causing the temperature to rise. Due to the linear relationship between the resistance of alloys and temperature, the heat loss can be calculated in real-time by monitoring the changes in resistance; After the formation of a transient temperature field in the sample, the instrument records the response curve of temperature over time, and combines it with a preset mathematical model (based on the theory of a disc-shaped heat source with step heating in an infinite medium) to directly calculate the thermal conductivity of the material. This process does not require the destruction of the sample structure and has minimal restrictions on the shape and size of the sample.
Precautions for using transient heat source thermal conductivity analyzer:
1. In terms of safety protection
-Preventing burns: Due to the involvement of heating operations, direct contact with high-temperature components such as newly tested samples and probes should be avoided during instrument operation to prevent burns. Especially when opening the instrument compartment door or replacing samples, extra caution should be taken.
-Electrical safety: Ensure good grounding of instruments to avoid safety issues caused by leakage. Do not dismantle the electrical circuits inside the instrument at will. If any faults are encountered, they should be repaired by professional personnel.
2. Precautions related to samples
-Avoid contamination and damage to the probe: Keep the sample clean to prevent impurities, dust, and other contaminants from adhering to the probe and affecting measurement accuracy. At the same time, when loading and unloading samples, handle them gently to prevent damage to the probe or other critical components.
-Control the moisture content of the sample (for some materials): For some materials with strong moisture absorption, it should be noted that their moisture content may significantly change the thermal conductivity of the material. If necessary, the sample can be pre treated in a dry environment before testing.
3. Environmental condition control
-Stable room temperature environment: Try to use instruments in environments with relatively stable temperatures, as temperature fluctuations can affect measurement results. If constant temperature conditions cannot be guaranteed, the range of environmental temperature changes and their possible impact on the results should be noted in the report.
-Reduce airflow interference: Avoid strong airflow passing through the testing area, such as direct blowing from a fan, as this can accelerate heat loss, interfere with normal heat transfer processes, and increase measurement errors.
4. Key points of operating standards
-Strictly follow the instructions: Different models of transient heat source thermal conductivity analyzers may have specific operating procedures and requirements. It is important to carefully read and follow the user manual of the instrument, and operate it correctly according to the steps.
-Regular maintenance: Regularly clean the dust and debris inside the instrument, check whether the connecting wires are loose, and replace severely worn parts in a timely manner to ensure the stable and reliable performance of the instrument.
5. Prudence in data processing
-Reasonable selection of data intervals: When processing data, it is necessary to select effective data intervals for analysis, excluding abnormal data in the initial stage (such as outliers caused by transient effects at the beginning of heating) and data segments with high noise in the later stage.
-Multi group data averaging: To improve the accuracy and reliability of the results, it is recommended to conduct multiple repeated experiments and then take the average of multiple sets of data as the result.