Degradation and protection phenomena of high-alloy Fe-Cr alloys in hot, multi-component gas systems

该项目旨在对高合金Fe-Cr合金在SO2和H2O以及含氯沉积物（KCl）下的热气体气氛中的损伤机制进行基础研究。这些材料用作各种燃烧发电厂中的热交换器管的材料。对生物质和生物质共燃发电厂中使用的材料的烟道气侧的损害是一个严重的问题，并且限制了这种发电厂的操作温度。 腐蚀产物的结晶和生长的基本方面将在降解的早期阶段通过随时间变化的老化实验进行研究。高纯度的模型合金（Fe-Cr）和模型气体成分将被用来关注元素Fe，Cr，S和Cl的反应。使用广泛的经典显微镜技术和先进的表征方法（例如X射线近边结构吸收光谱（XANES））对形成的腐蚀区进行定性和定量相分析。经典显微镜与XANES的结合导致对现有反应产物的极其精确的验证。这种方法应有助于显示金属离子和气体组分在反应产物的晶体结构上的扩散和传输路径。在反应过程中，在一个专门设计的光反应堆中，通过原位能量色散X射线衍射，将直接跟踪腐蚀早期阶段的结晶和生长。第一个目的是研究保护性Cr2 O3的形成。为此，使用实验装置，允许材料暴露于热烟气。首先，对三种不同的高合金（Cr>15Ma%）模型合金进行了反应时间为12 h的时效试验

The proposed project aims at the fundamental investigation of the damage mechanisms of high-alloyed Fe-Cr alloys in a hot gas atmosphere under SO2 and H2O and under chlorine-containing deposits (KCl). These materials are used as materials for heat exchanger tubes in various combustion power plants. The damage to the flue gas side of the materials used in biomass and biomass co-fired power plants is a serious problem and limits the operating temperature of such plants. Fundamental aspects of crystallization and growth of corrosion products will be investigated at an early stage of degradation by means of time-dependent ageing experiments. High purity model alloys (Fe-Cr) and model gas compositions are to be used to focus on the reaction of the elements Fe, Cr, S and Cl involved. The qualitative and quantitative phase analysis of the formed corrosion zones is performed using a broad spectrum of classical microscopy techniques and advanced characterization methods, such as X-ray near-edge structure absorption spectroscopy (XANES). The combination of classical microscopy with XANES leads to an extremely precise verification of the existing reaction products. This approach should help to show diffusion and transport paths of metal ions and gas components over the crystal structure of the reaction products. Crystallization and growth at a very early stage of corrosion will be followed directly during the reaction by in-situ energy dispersive X-ray diffraction in a specially designed light reactor.The project aims at three questions. The first objective is to investigate the formation of protective Cr2O3. For this purpose, an experimental setup is used that allows materials to be exposed to a hot flue gas. First, ageing tests are carried out on three different high-alloyed (Cr>15Ma%) model alloys with reaction times 12h