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。特别地，完全稳定的立方体材料在这方面具有很大的意义。该项目研究了与此类应用相关的炉渣和熔体对氧化锆的腐蚀，以便为耐火材料和热/环境屏障涂层的可靠性评估和寿命预测提供基础，这些涂层可能会被硅酸盐熔体降解。我们从CAS、CMAS中选择了七种不同复杂程度的炉渣，并用YSZ材料制作或购买了衬底。更新了加热台显微镜。我们已经表明，这是可能的investaigate润湿行为，这种方式。我们模拟了熔体的碱度和氧化锆溶解后熔体性质的变化。此外，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，在装有熔体的反应坩埚周围有一个保护坩埚。如果给出闭合孔隙度，则该技术是成功的。否则，我们观察到二次烧结渗透熔体。腐蚀动力学受几个过程控制：a）稳定剂Y2 O3从晶粒中浸出，B）氧化锆基质溶解在熔体中，c）现有晶界通过过程（B）扩大，d）通过相变产生新晶粒。来自原生孔隙的额外路径使事情变得更加复杂和快速。尽管这些相互作用，我们观察到一个“准层生产”的腐蚀前沿的进步。因此，可以同时跟踪溶解和渗透过程作为时间的函数。最有前途的方法是单晶的研究和烧结材料的比较。因此，在第一个时期，我们提供了基础（在仪器，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，我们申请再延长两年的资助期，这将使总数延长到4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.