Zirconia based thermal barrier coatings for extended temperature ranges

适用于扩展温度范围的氧化锆基热障涂层

• 批准号: 445688870
• 负责人: Privatdozent Dr.-Ing. Mathias Galetz
• 金额: --
• 依托单位: Fachgebiet und Institut für Werkstoffkunde
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/445688870?language=en
• 关键词: Zirconia; based; thermal; barrier; coatings

The research project will focus on two major aspects to increase the operation temperature of gas turbines. On the one hand, possibilities to increase the operation regime of the standard material 8YSZ to temperatures above 1250°C will be investigated. On the other hand, plasma-sprayed monolayers made out of alternative ceramics will be produced, which have compared to 8YSZ an improved phase stability at high temperatures and are suitable for an application at 1600°C. A first focus is a study of the transformation processes under changed process and operation conditions, which are necessary for an evaluation of lifetime in the extended operation regime of future thermal barrier coatings.For an extension of the operation regime of 8YSZ above 1250°C the influence of microstructure on the phase transformation and the sintering behavior of the standard material 8YSZ will be investigated at very high temperatures. As the high temperature stability and hence the lifetime of the thermal barrier coatings at very high temperatures are depending strongly on phase transformation and the sintering behavior, an understanding of the underlying mechanisms and of the development with time of these properties is of fundamental importance for the possible application fields. Both processes are temperature dependent and accelerated at high temperatures, however, there are hints, that with an especially fine-grained microstructure both phase transformation and sintering can be suppressed. In addition, very fast cooling rates can suppress the phase transformation. One objective is therefore, to identify underlying mechanisms to determine a suitable selection of process parameters or special coating processes for a production of coatings, which show due to their microstructural features improved phase stability and sintering behavior. The influence of the cooling rate on the phase transformation will be clarified by specific experiments and could additionally lead to an extension of the operation regime of the standard material 8YSZ.The second part of the project, which is dealing with new materials for an operation at 1600°C, is the development of a thermal barrier coating out of an alternative zirconium based ceramic. For that four representative candidates from the co-doped zirconium oxides were selected, which have compared to 8YSZ an extended temperature stability. The selection includes on the one hand simple systems, in which strategies for doping as stabilization of the tetragonal phase, increasing the fracture toughness, or improving the tetragonality are applied (Ta-Y, Ce/Sc-Y). In addition, the co-doping with alumina will be investigated. Finally, an already commercial available complex doped systems will be selected as a benchmark. Also here it has not been analyzed in depth how processing, microstructure and operation conditions influence the stability of the system.

该研究项目将集中在两个主要方面，以提高燃气轮机的运行温度。一方面，将研究将标准材料8 YSZ的操作制度提高到1250°C以上的温度的可能性。另一方面，将生产由替代陶瓷制成的等离子体喷涂单层，与8 YSZ相比，其在高温下具有改善的相稳定性，并且适用于1600°C的应用。第一个重点是研究在改变工艺和操作条件下的相变过程，这对于评估未来热障涂层在扩展操作范围内的寿命是必要的。为了将8 YSZ的操作范围扩展到1250°C以上，将研究在非常高的温度下微观结构对标准材料8 YSZ的相变和烧结行为的影响。由于热障涂层的高温稳定性以及因此在非常高的温度下的寿命在很大程度上取决于相变和烧结行为，因此理解这些性能的基本机制和随时间的发展对于可能的应用领域具有根本的重要性。这两个过程都依赖于温度，并在高温下加速，然而，有迹象表明，具有特别细晶粒的显微组织，相变和烧结都可以被抑制。此外，非常快的冷却速率可以抑制相变。因此，一个目的是确定潜在的机制，以确定用于生产涂层的工艺参数或特殊涂覆工艺的合适选择，所述涂层由于其微观结构特征而显示出改善的相稳定性和烧结行为。冷却速率对相变的影响将通过具体的实验来阐明，并可能导致标准材料8 YSZ的操作范围的扩展。该项目的第二部分涉及在1600°C下操作的新材料，是开发替代锆基陶瓷的热障涂层。为此，从共掺杂的氧化锆中选择了四种代表性候选物，其与8 YSZ相比具有延长的温度稳定性。一方面，选择包括简单的系统，其中应用掺杂策略来稳定四方相、增加断裂韧性或改善四方性（Ta-Y、Ce/Sc-Y）。此外，将研究与氧化铝的共掺杂。最后，一个已经商业化的复杂的掺杂系统将被选为基准。此外，这里还没有深入分析加工、微观结构和操作条件如何影响系统的稳定性。