Tailoring of Grain Boundary Chemistry of Alumina Ceramics for Corrosion Resistance

9625354目前可用的商用陶瓷通常不适合高腐蚀性应用，因为它们含有可腐蚀的玻璃晶界相。这种相是由于液相烧结添加剂的商业使用或粉末纯度和加工控制不当造成的。在这个项目中，我们对氧化铝陶瓷及其在氟化氢（HF）环境中的腐蚀性能特别感兴趣，以期在氟化工制造中开发改进的建筑材料。杜邦公司的腐蚀研究发现，少量MgO(0.05%)，一种经典的固溶烧结助剂，即使在存在玻璃形成杂质的情况下，也能提高氧化铝在HF中的腐蚀速度。MgO起作用的原子机制尚不清楚，主要是因为它对其他阳离子杂质的影响尚不清楚。芝加哥大学和杜邦公司拟议合作的目标是提高我们对晶界化学及其对腐蚀行为的影响的理解，以期设计耐腐蚀陶瓷。该方法将是开发制造策略，消除或调整玻璃晶界的性质。利用高分辨率成像二次离子质谱法（SIMS）研究了系统设计的氧化铝组合物中痕量掺杂剂和杂质的分布。本研究的主要重点是将氧化铝的晶界化学与大块材料的腐蚀行为联系起来。这些信息将有助于设计耐各种材料腐蚀的商用陶瓷材料。＊＊＊

9625354 Levi-Setti Commercial ceramics that are presently available are generally unsuitable for highly corrosive applications because they contain corrodible glassy grain boundary phases. Such phases result from the commercial use of liquid- phase sintering additives or from poor control of powder purity and processing. In this project, we are interested particularly in alumina ceramics and their corrosion properties in hydrogen fluoride (HF) ambients, with a view to developing improved materials of construction in the fluorochemical manufacturing. Corrosion research at DuPont has led to the discovery that a small amount of MgO (0.05%), a classic solid-solution sintering aid, improves the corrosion rate of alumina in HF, even in the presence of glass-forming impurities. The atomistic mechanism by which MgO functions is not understood, mainly because its influence on other cation impurities is not known. The goal of the proposed collaboration between the University of Chicago and DuPont is to improve our understanding of the grain boundary chemistry and its effect on corrosion behavior, with a view to designing corrosion-resistant ceramics. The approach will be to develop fabrication strategies that eliminate or adjust the nature of glassy grain boundaries. The distributions of trace dopants and impurities in a number of systematically designed alumina compositions will be studied by high resolution imaging secondary ion mass spectrometry (SIMS). %%% The principal focus of this study is to correlate the grain boundary chemistry of aluminum oxide to the corrosion behavior of the bulk material. This information will aid in the design of commercial ceramic materials that are resistant to corrosion by a variety of materials. ***