取样对激光法测定导热系数的影响

Effect of sampling on thermal conductivity determination by laser flash method

以建筑陶瓷、石墨砖和Si3N4-SiC砖为主要试样，研究取样数量、取样位置及其方向对激光法测定材料导热系数结果的影响。结果表明，对于均质材料，随着取样数量的增加，导热系数的测定结果趋于其真值，结合目前设备的技术条件，认为取2～3个样品进行测试即可获得较理想的结果；而对于非均质材料，取样位置和方向都对其导热系数的测定结果有很大的影响，这主要是由于非均质材料的结构或组成随着取样位置和方向的不同而造成的，非均质材料的取样数量至少为5个。

Effect of sampling amount, position and direction on thermal conductivity determination by laser flash method was studied by using building ceramics, graphite bricks and Si3 N4-SiC bricks as experimental materials. The results show that： for homogeneous materials, determined thermal conductivity moves close to the true value with the sample number increasing, and with contemporary technical conditions 2-3 samples are needed for satisfactory results; for heterogeneous materials, sampling position and direction have serious influence on thermal conductivity determination, which can be explained by different compositions and structures caused by the un-uniformity of materials, and therefore no fewer than 5 samples are needed.