瞬态高温条件下Ti、Zr金属氢化物的释氢机制研究

TiH2 and ZrH2 are widely used in the storage, transfer and transform of hydrogen energy, such as the laser ion source, nuclear fuel, neutron moderator and the preparation of foamed Al alloy. It is of great importance of both application merit and research significance to study the desorption mechanism under transient high temperature of TiH2 and ZrH2, which usually worked under the irradiation of pulsed beams or fast heating-up.The thermal decomposition mechanism of TiH2 and ZrH2 at linear ramp rate has been studied by many researchers with the help of thermal desorption spectroscopy so far. Compared with that, the desorption mechanism of TiH2 and ZrH2 under the irradiation of pulsed energy has not been clearly revealed until now. To solve the problem, the methods of combined experiment diagnosis and numeric simulation are used to study the behaviors of hydrogen desorption under pulsed laser irradiation. The hydrogen desorption rate and surface erosion will be investigated by a pulsed laser induced desorption method and surface morphology analysis. Meanwhile, a heat and mass transfer model will be established to describe the temperature distribution, evaporation, melt, ablation and change of the structure of metal hydride induced by high power energy. The study of this project not only helps to obtain the behavior of hydrogen desorption of metal hydride under pulsed radiation, also lays the foundation of the design of novel laser ion souces, sability analysis of nuclear fuel and preparation process optimization of foamed Al alloy, etc.

TiH2与ZrH2在氢能的存储、传输与转换中应用广泛，如应用于激光离子源、核燃料、中子慢化、泡沫铝合金制备等领域。由于其通常工作在脉冲束流辐照或快速升温环境下，研究其在瞬态高温作用下的释氢机制具有重要的科学与工程应用价值。迄今为止，研究者采用热解吸谱方法揭示了其在缓慢线性升温条件下的热分解规律，但对其在脉冲能量作用下的释氢机制尚未完全掌握。本项目提出采用实验诊断和数值模拟相结合的方法开展TiH2与ZrH2在瞬态高温下的释氢机制研究。实验上，利用脉冲激光热解吸系统在线测量和表面形貌及结构离线分析方法开展释氢规律研究。理论上，建立金属氢化物在脉冲能量作用下的传热与传质模型，揭示材料的温升、气体释放、熔化、烧蚀和相结构改变的物理规律。本工作对阐明金属氢化物在脉冲能量作用下的释氢机制有重要意义，为开展新型激光离子源设计、核燃料稳定性分析、泡沫铝合金制备工艺优化等工作奠定基础。

TiH2与ZrH2在氢能的存储、传输与转换中应用广泛，如应用于激光离子源、核燃料、中子慢化、泡沫铝合金制备等领域。由于其通常工作在脉冲束流辐照或快速升温环境下，研究其在瞬态高温作用下的释氢机制具有重要的科学与工程应用价值。本项目主要在以下三个方面取得进展：（1）建立了脉冲激光作用下TiH2与ZrH2的传热和传质物理模型并进行了数值计算，获得了温度和氢原子浓度随时间和空间的分布情况，获得了表面氢气释放速率、释放量等参数。研究发现，氢的消耗主要发生在距表面0.1 μm的范围内，而温度变化主要发生在距表面1 μm的范围内。（2）建立了脉冲功率作用下TiH2与ZrH2瞬态释气过程的测量方法，发现TiH2放气量随工作次数呈逐渐降低并最终趋于稳定趋势，与数值模拟结果规律一致；发现由于氢原子聚集形成的气泡在高温下穿过熔融的金属表面并破裂，材料表面会形成小的孔洞。（3）采用TG-TDS联用技术研究了TiH2与ZrH2的热分解行为，系统阐述了升温速率、氢浓度、保温温度等参数对氢化钛热分解行为的影响，发现了不同条件下氢化钛材料的相变路径。通过本项目研究，不仅取得了预期的研究成果，而且成果也可推广至其它金属氢化物材料。