Active oxidation protection coatings for Mo-Si-B high temperature materials

由于效率的提高，高温稳定材料Mo-Si-B作为燃气轮机的替代材料受到了广泛的研究。在该材料体系中尚未解决的问题是其氧化行为：Mo组分以Mo（IV）氧化物形成的形式显示出粘结。本征材料保护机制-近表面Si和B的氧化及其形成氧扩散限制玻璃层的反应-是不足的。本工作的目的是开发一种新型的活性多层环境屏障涂层，其具有在低温（500 °C至800 °C）下形成的初始保护玻璃层，以及在使用条件（1100 °C至1200 °C）下的高氧捕获能力和氧扩散抑制层。这些层基于填充有颗粒状的含Si-、B-、Ti和/或Al的组分的全氢聚硅氮烷，所述颗粒状的含Si-、B-、Ti和/或Al的组分具有可变的颗粒尺寸和体积分数，并且其将通过浸渍涂覆Mo-Si-B基底材料，随后进行热处理以转化成活性陶瓷材料（层调节）并在类似于使用的条件下进行热处理来施加。在类似使用条件下进行调节和处理后，将采用标准方法对固态样品进行表征。XPS研究将更深入地了解保护层的形成机制，纳米压痕实验可以表征和理解层的机械性能。结果将用于模型开发，以了解物理化学层的形成及其在使用条件下的功能。这将有助于将保护层的开发转移到Mo-Si-B耐火基合金之外。

Due to an increase in efficiency, the high-temperature stabile material Mo-Si-B is intensely investigated as a substitute material in combustion turbines. A problem not solved yet in this material system is its oxidation behavior: the Mo component shows pesting in form of Mo(IV) oxid formation. The intrinsic material protection mechanism– the oxidation of near-surface Si and B and its reaction to form an oxygen diffusion limiting glass layer – is insufficient. Aim of this work is to develop a novel-type, active multi-layer environmental barrier coating with an initial protective glass layer formation at low temperatures (500 °C to 800 °C), and a high oxygen-trapping capacity and oxygen diffusion inhibition layer under service conditions (1100 °C to 1200 °C). These layers are based on a perhydropolysilazane filled with particulate Si-, B-, Ti and/or Al-containing components of variable particle size and volume fraction, and it will be applied by dip coating of Mo-Si-B substrate materials followed by heat treatment for the conversion into an active ceramic material (layer conditioning) and heat treatment under service-like conditions. Standard methods will be carried out for solid-state sample characterization after conditioning and treatment under service-like conditions. XPS investigations will give a deeper insight into protective-layer formation mechanisms and nanoindentation experiments allow to characterize and to understand the layers´ mechanical properties. The results will be used for models development to understand the physicochemical layer formation and their function under service conditions. This will help to transfer the development of protective layers for other than Mo-Si-B refractory based alloys.