Study On The Thermal Conductivity Measurement Of Thin Samples By Hot Disk Thermal Constants Analyser

The thermal conductivity, which can directly reflect materials’ capacity of heat transmission, is one of vital thermophysical parameter for its application. Therefore, it’s meaningful to study the measuring method of materials’ thermal conductivity. Recently, the Transient Plane Source Method(TPS) has attracted much more attention due to its short measure time, high accuracy and great adaptability to test samples. This method can be used to measure various types of material, such as solid bulk, powder, liquid, gasses, film and anisotropic materials. Aiming at measuring the thermal properties of materials available as thin slabs, therefore the Hot Disk Slab Method was developed from TPS technology. But now, there is little researchers focused on the Hot Disk Slab Method. During the daily use of Hot Disk slab method, we found that the measuring results were affected by heating power, heating time and the thickness of samples. Meantime, the accuracy of measurement is relatively low.In this work, the fundamental theory of TPS and Hot Disk Slab Method was provided. Then four kinds of high Conductive materials with different thickness were used as test sample to study the relationship between results and heating time, heating power and the change of samples’ thickness. The experimental results indicated that: while the heating power of 316 Stainless Steel, Q235-A Carbon Steel and pure Aluminum were set as 0.40 W, 0.50 W and 1.50 W respectively, their thermal conductivity measuring results got smaller with the increase of transient measuring time. When the transient measuring time increased from 2.5s to 5.0s, 316 stainless steel and Q235-A Carbon steel’s value of thermal conductivity dropped sharply. However, with the further augment of the measuring time, the thermal conductivity decreased slowly and the effect of results diminished with measuring time. As for 316 stainless steel and Q235-A Carbon steel, the thermal conductivity measuring results, which were obtained by using 5501 sensor and 5.0 seconds measuring time, rise up with the increase of heating power, On the other hand, the thermal conductivity of pure Aluminum and pure copper nearly maintain constant with the increase of heating power. The thermal conductivity results measured by 8563 sensor decreased with the increase thickness.In order to decrease the Relative Error of measuring results, we try to correct the formula owing to the existence of heat loss in the measure process. According to the fundamental theory of Hot Disk Slab Method, the total heat losses in transient measuring process were calculated. Eventually, the Hot Disk Slab Method’s modified formulas were obtained in account of the heat losses in transient time.Furthermore, Aluminum and Copper slab samples with the purity of larger than 99.9% were measured by Hot Disk Slab Method. Then the measurement results were compared with the standard materials’ reference data to check the validity of the above modified formula. The results found that the modified relative error of Aluminum and Copper thermal conductivity were decreased by 38.4% and 54.7% respectively.