Corrosion of ZrO2 by slags and melts

含氧化锆材料是替代含碳耐火材料的潜在候选材料。特别是完全稳定的立方体材料在这方面有很大的兴趣。该项目研究了与此类应用相关的炉渣和熔体对氧化锆的侵蚀，以便为耐火材料和可能被硅酸盐熔体降解的热/环境屏障涂料的可靠性评估和寿命预测提供基础。我们从中科院选择了七种炉渣，从不同复杂程度的CMA中选择了七种，并用YSZ材料制造或购买了基板。对加热台显微镜进行了改造。我们已经证明，用这种方法研究润湿行为是可能的。我们模拟了熔体的碱度和氧化锆溶出后的性质变化。此外，还开发了测量这种溶解的饱和值的方法，并提取了第一个数字。开发了一种特殊的坩埚类型的实验，在装载熔体的反应坩埚周围设置一个保护性坩埚。如果给出闭合孔隙度，这项技术是成功的。另外，我们观察到了熔体渗入的二次烧结。腐蚀动力学受以下几个过程控制：a)稳定剂Y_2O_3从晶粒中析出，b)氧化锆基质溶解在熔体中，c)工艺(B)使现有晶界变大，d)通过相变产生新的晶界。来自原生孔隙度的额外路径使事情变得更复杂和更快。尽管有这些相互作用，我们观察到腐蚀前沿的“准层产生”推进。因此，可以同时跟踪溶出和渗透过程作为时间的函数。最有希望的方法是研究单晶，并与烧结材料进行比较。因此，在第一阶段，我们提供了基础(在设备、方法和分析方面)。这项工作被认为是成功的，但持续时间比预期的要长。因此，我们申请延长两年的资助期，将总资助期延长至四年。

Zirconia containing materials are potential candidates for the replacement of carbon containing refractories. In particular fully stabilized cubic materials are of great interest in this respect. The project investigates the corrosion of Zirconia by slags and melts relevant for such applications in order to provide the basics for the evaluation of reliability and life time prediction of refractories and thermal/environmental barrier coatings with a potential of beeing degraded by silicate melts. We have chosen seven slags from CAS, CMAS with varying complexity and made or bought substrates from YSZ materials. A heating satge microscope was renovated. We have shown that it is possible to investaigate the wetting behavior this way. We have simulated the basicity of the melts and the change in character by dissolution of Zirconia. Furthermore methods to measure saturation values for this dissolution were developed and first numbers extracted. A special crucible type of experiment was developed, with a protective crucible around a reactive crucible loaded with the melt. The technique is successful, if closed porosity is given. Otherwise we observe secondary sintering by infiltrating melt. The kinetics of corrosion are controlled by several processes: a) stabilser Y2O3 is leached from the grains, b) zirconia matrix is dissolved in the melt, c) existing grain boundaries get enlarged by process (b) and d) new grains are produced via phase transformations. Additional paths from primary porosity makes things more complex and faster. Despite these interactions we observe a "quasi-layer producing" advance of the corrosion front. Hence it is possible to follow the dissolution and penetration process simultaneously as a function of time. The most promising approach is the investigation of single crystals and the comparison to the sintered material. Thus in the first period we have provided the basement (in terms of apparatus, methods and analytics). This work is regarded as successful, but has lasted longer then anticipated. Therefore we apply for a further funding period of two years, which would prolong the total to 4 years.