导热脂低温热导率的测试研究

Research and Measurement of Thermal Conductivity of Thermal Conductive Grease at Cryogenic Temperature

导热脂的低温热导率是研究宇航用导热脂的重要参数,"瞬态热线法"是常用的测量方法之一,但受使用条件限制,实际应用中容易产生较大误差。本文提出采用改进的"瞬态热线法"即对标准流体与试样进行测量比对的方法,用于导热脂低温热导率的测量,减小了测试方法的系统误差,因而保证了测量的相对误差小于6%。在测量装置上,采用廉价的康铜丝取代了传统使用的铂丝,设计采用了容易进行拆洗的低温试验装置。文章讨论了影响导热脂低温热导率的因素。提出测量加热时间要在2s～3s之内以防止对流,分析了比对状态的误差影响,并给出了两种导热脂低温热导率与温度关系曲线。分析表明本文提出的试验方法可以满足宇航用导热脂研究的需求.

The thermal conductivity at cryogenic teinperature is one of important properties for the thermal conductive grease applied in aerospace. A transient hot-wire method is one of measurement methods in common use. Because of applied conditions the system error is large easily. In order to reduce the system error in measurement method of thermal conductivity of the thermal conductive grease at cryogenic temperature, an improved transient hot-wire method is adopted. The measuring equipment is compared with the normal data, and the measured relative error is less than 6%. In measuring equipment, a traditional platinum wire is replaced by the cheap Constantan wire, and in the design to the experimental device that dismantles to wash easily is adopted in the design. Factors influencing thermal Conductivity of the thermal conductive grease at cryogenic temperature are discussed, and it is put forward that the heating-up time for measurement should be in 2 s-3 s to prevent convection, the measured relative error compared with the normal data is analyzed, and two kinds of the curves between thermal conductivity of the thermal conductive grease at cryogenic temperatures are given in the paper. By the analysis shows that the improved transient hot-wire method is satisfaction method at cryogenic temperature for aerospace.