用于储氢的TiZrNi合金的传热机理研究

Study of heat transfer mechanism of TiZrNi alloy for hydrogen storage

钛锆镍(TiZrNi)合金具有吸收大量氢气进入晶格的能力,其中吸收和储存氢气的过程与热导率密切相关,较高的热导率能够加速吸收氢气的过程。研究了无定形态的TiZrNi合金薄膜在室温周围几个温度点的传热机理。通过频域热反射法(Frequency domain thermoreflectance)进行热导率测量,测得的室温热导率(k_(t))低于5 W/(m·K)以下,与一些高熵合金处于同一数量级,但在室温下大约比储氢领域主要研究的有机金属框架材料(metal-organic frameworks)高6倍。并且随着温度从室温上升到400 K,TiZrNi合金热导率缓慢上升。通过四探针法测量电导率(σ),再根据测量塞贝克系数(S)确定实际洛伦兹常数(L),由威德曼-弗朗兹(Wiedemann-Franz law)定律估算电子热导率(k_(e))的值,对比k_(e)与k_(t),结果表明TiZrNi总热导率主要由电子贡献,比例达到80%以上。

TiZrNi alloy has the ability to absorb a large amount of hydrogen into its lattice[1].The thermal conductivity is closely related with hydrogen absorption[2],higher thermal conductivity can speed up the process of hydrogen absorp⁃tion.In this paper,the heat transport mechanism of amorphous TiZrNi alloy film aroundroomtemperature was investiga⁃ted.The frequency domain thermos⁃reflectance(FDTR)was used to measure the thermal conductivity of alloy.The measuredthermal conductivity of TiZrNi is below 5 W/(m·K),as same as the magnitude of that of high entropy alloys(HEA),roughly 6 times of the metal⁃organic frameworks(MOF)materials usually applied in hydrogen storage at room temperature[3].The thermal conductivity(k_(t))of TiZrNi alloy increases slowly as the temperature rises from 300 K to 400 K.The electrical conductivity(σ)was measured by using a four⁃point probe and the Lorentz constant(L)was determined by measuring the Seebeck coefficient(S),then the thermal conductivity of electrons(k_(e))was estimated by using Weidemann⁃Franz law.The electrons roughly accounts for 80%contribution to the thermal conductivity of TiZrNi alloy by comparison of ke andkt.