Sn元素对氢气阀高压温控Pb-Bi共晶合金熔断性能的影响研究

Effect of Sn Elements on the Fuse Properties of Pb-Bi Eutectic Alloy with High Pressure Resistance and Temperature Control for Hydrogen Valve

摘要:

车载储氢气瓶瓶口阀作为车载高压储氢系统的核心安全部件，需满足70 MPa级储氢系统在极端工况下的热失控防护需求。因此，针对70 MPa车载储氢气瓶瓶口阀用温控熔断合金展开了系统地研究。选取Pb-Bi共晶合金作为基体材料，采用高频真空熔炼炉，在Ar气保护环境下向Pb-Bi共晶合金分别添加1%—5%（质量分数）的Sn元素进行合金熔炼，以制备出额定温度为（110±5） ℃、承受压力为70 MPa的温控易熔Pb-Bi-Sn合金。利用X射线衍射（XRD）、扫描电子显微镜（SEM）、能谱分析（EDS）等表征手段，对合金的熔点、显微组织、物相组成、硬度及抗压强度进行测试和分析。研究结果表明，Sn元素的添加并未形成新的金属间化合物相，相组成主要包括Sn相、Bi相及Pb₇Bi₃金属间化合物相（IMC），Sn元素则是以固溶体相形式存在。由于Sn元素增加了合金的固溶度，改变了合金的原子间距及原子结合力，从而使合金熔点下降、熔化潜热降低及熔化温度范围增加。此外，Sn元素的固溶强化作用与基体中析出Sn相的第二相强化协同，使得合金的强度、硬度均得到显著提升。随着Sn元素含量的增加，合金的硬度及抗压强度均出现上升趋势。当Sn质量分数增至5%时，所制备的(Pb56Bi)5Sn易熔合金的抗压强度达到61.4 MPa、硬度提高至17.28 HV，相较于Pb-Bi共晶合金，其强度提高了29.53%。同时，合金的熔化区间为105.2—112.5 ℃，熔化温度范围为7.3 ℃，能够满足氢气安全阀中温控元件的应用需求。通过在Pb-Bi共晶合金中添加Sn元素制备协同温控易熔合金，为高压氢气储运系统的安全防护提供了材料支撑。(专精特新·特殊环境材料服役行为专辑十五之八)

Abstract:

This study investigates the optimal composition of a fusible alloy with temperature control for the combined valve of a 70 MPa high-pressure on-board hydrogen storage bottle， using Pb-Bi eutectic alloy as the matrix material. By adding Sn elements to Pb-Bi eutectic alloy to design and prepare a temperature-controlled melting alloy with a rated temperature of （110±5） ℃ and the ability to withstand a 70 MPa pressure. Sn elements were added in varying amounts （1%—5%） under an Ar-protected atmosphere using a high frequency vacuum melting furnace， followed by alloy solidification through furnace cooling. The melting point， microtissue， phase composition， hardness and compressive strength of the resulting Pb-Bi-Sn alloy were analyzed using X-ray diffraction （XRD）， scanning electron microscopy （SEM）， and energy-dispersive spectroscopy （EDS）. The results indicate that the addition of Sn element led to the formation of Sn phase， Bi phase and Pb₇Bi₃ intermetallic compound phase （IMC） in the alloy matrix， without the emergence of new intermetallic compounds. Sn element primarily existed as a solid solution phase， increasing the solid solubility of the alloy and altering atomic spacing and binding force. Consequently， the melting point and latent heat of fusion decreased， while the melting temperature range slightly expanded. Additionally， Sn contributed to solid solution strengthening， and the excess Sn phase precipitated from the liquid phase， dispersing uniformly within the matrix as a second phase， thereby enhancing the mechanical properties of the alloy. With increasing Sn content， both hardness and compressive strength exhibited an upward trend. When the Sn content reached 5%， the compressive strength of the （Pb56Bi）5Sn fusible alloy reached 61.4 MPa， reflecting a 10% increase compared to the Pb-Bi eutectic alloy. Futhermore， the （Pb56Bi）5Sn fusible alloy exhibited a melting interval of 105.2—112.5 ℃ with a melting temperature range of 7.3 ℃， demonstrating its suitability for use in the temperature control components of hydrogen safety valves.