ABSTRACT

Since ancient times, the use of high-tin bronze alloys (>17 wt.%) has been mainly limited to the production of specific objects such as mirrors and bells. High-tin bronzes can show distinctive colour reflection, as well as mechanical properties and corrosion resistance that clearly distinguish them from the classical bronze composition (with 8–12 wt.% tin). In the present study samples of archaeological high-tin bronze bells were studied by optical microscopy, SEM-EDX, and Raman imaging with the aim of characterising their microstructural long-term corrosion patterns. Results show the presence of high quantities of δ phase, when compared to the classical bronze composition, which makes some corrosion structures more visible in these alloys. The corrosion morphologies show selective corrosion of different metal phases along depth of corrosion, which were attributed to different oxygen potentials. This study proposes a classification of four types of corrosion structures occurring in two-phase bronzes as a consequence of aeration conditions during burial time and aeration within the corrosion structure.

摘要

自古以来，高锡青铜合金（>17 wt.%）的使用主要限于生产特定的物体，如镜子和铃铛。高锡青铜可以显示出独特的颜色反射，以及机械性能和耐腐蚀性，这与经典青铜成分（含 8-12 wt.% 锡）明显不同。在本研究中，通过光学显微镜、SEM-EDX 和拉曼成像研究了考古高锡青铜钟的样品，目的是表征其微观结构的长期腐蚀模式。结果表明，与经典的青铜成分相比，存在大量的 δ 相，这使得这些合金中的一些腐蚀结构更加明显。腐蚀形态显示不同金属相沿腐蚀深度的选择性腐蚀，这归因于不同的氧势。本研究提出了在两相青铜中发生的四种腐蚀结构的分类，这是由于埋藏期间的曝气条件和腐蚀结构内的曝气造成的。