导温系数测量的一个改进

来源期刊：中南大学学报(自然科学版)1984年第3期

论文作者：薛健

文章页码：1 - 9

关键词：导温系数； 传统方法； 实验条件； 温升法； 测量； 热损； 实验结果； 样品； 程序框图； 改进

摘    要：本文论述了相对温升法测量材料导温系数的原理及实验结果。与传统方法相比,当实验条件符合理论要求时二者结果一致,当实验条件存在热损时,该方法较传统方法精度高。

Abstract: The technigue described here was proposed in 1982, and it has an indepen- dent heat loss diffusivity measurement. According to Parker’s theory, the dif- fusivity can be found from the fundamental relationship of this new method: T₁ / T₂ = （1 + 2 multiply from n - 1 to ∞ （-1）ⁿ exp （-n²ω₁）） / (1 + 2 multiply from n - 1 to ∞ （-1）ⁿ exp （-n²exp （-n²ω₂）） （1） where ω = π²at / L², ω² = ω₁ + △ω, T₁, T₂ the excess temperatures at the corres- ponding time t₁, t₂ of the rear surface temperature time history, and L the thickness of the sample. Using Cowan’s formula, Eg（1） is programmed into a computer and the output data show that, the diffusivity a of measurement is a function of ω₁, △ω, and heat loss parameter. A neodymium glass laser was used in this study. The results of the experiment in which the new technigne had been utilized were presented for Amrco iron and compared with the results based on the traditional t_{1 / 2} method. The elem- entary conclusion is: 1. If the diffusivity measurements are under the ideal boundary and initial conditions, whether t_{1 / 2} method or the new method is usod, the correct diffusi- vity value can always be obtained. 2. When heat loss is existing, if ω, △ω are chosen correctly, the thermal diffusivity by using the new method can be obtained without accounting for the heat losses. For example, under the small heat losses, if ω₁ ≌ 1. 7 and △ω ≌ 0.1, the diffusivity measurement is independent of heat iosses.