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本文在复合黑体法测量比热的基础上,提出了一种精度更高的激光比热测试方法。在样品的前表面加上一个反射率很高的反射壳体,进入复合黑体空腔内的光能除少部分被反射壳体吸收外,绝大部分被样品所吸收。而对于壳体吸收的那部分能量,本文从理论上推出了一个计算公式,应用此公式以及对激光能量和样品温升的测试,即可以较高的精度确定样品的比热。由于壳体与样品组成一个人造黑体,对激光能量是绝对吸收(当然除了极少部分从进光孔逸漏出去的光能),故可实现绝对测量。通过实测和误差分析,测定Armco纯铁、电解镍比热值的误差均在±3％以内。
In this paper, based on the composite blackbody method to measure the specific heat, a more accurate laser specific heat test method is proposed. In the front surface of the sample plus a reflective shell with high reflectivity, into the composite blackbody cavity light energy except for a small part of the reflected shell absorption, the vast majority of the sample is absorbed. And for the part of the energy absorbed by the shell, this paper theoretically put forward a formula, the use of this formula and the laser energy and sample temperature rise test, that can be higher precision to determine the specific heat of the sample. As the shell and the sample form an artificial black body, the laser energy is absolutely absorbed (except of course, except for a very small part of the light escaping from the optical aperture), it can achieve absolute measurement. Through the measurement and error analysis, the determination of Armco pure iron, electrolytic nickel specific heat value of the error are within ± 3%.