Harnessing nanolaminate coatings for high temperature applications

基于MAX或MA B相（其中M是前过渡金属，A是A族元素，X是碳或氮，并且B是硼）的纳米层压涂层结合了联合收割机独特的陶瓷和金属材料性质，为高温环境中的应用提供了显著的潜力。在该项目中，将验证通过各种PVD技术沉积的氧化铝形成MAX和MAB（M = Cr或Ti，A = Al）纳米层压涂层的制造，并阐明其在高温下干燥和潮湿环境下的性能。这是第一次，三种不同的PVD技术可在合作机构在波兰和德国，包括高功率脉冲磁控溅射，直流和反应磁控溅射和封闭空心阴极PVD。比较和联合收割机这些技术的可能性，使一个独特的机会，了解各种沉积参数的纳米层压涂层的性能的影响。涂层将应用于金属间化合物TiAl和陶瓷SiC。该项目将侧重于开发由氧化铝组成的保护性热生长氧化层及其在长期高温暴露期间的演变。一个有前途的寿命改善，预计由于稳定的氧化铝层的富铝基板提供的补充效果，从而防止由于铝耗尽的MAX/MAB相涂层的退化，通过向内扩散到基板材料。此外，众所周知的TiAl的机械性能的劣化的保护，但脆性涂层可以通过沉积韧性MAX或MAB相的纳米层压材料来防止。在碳化硅的情况下，必须防止水蒸气腐蚀。最先进的环境屏障涂层系统基于稀土硅酸盐，具有多达4个不同的层。因此，评估了它们被单层和氧化铝形成的MAX或MAB相基涂层替代的可能性，提供了可持续的原材料使用。将特别注意的纳米层压材料在高温下暴露的粘附性，以及涂层和惰性陶瓷SiC之间的界面设计。通过实验和热力学模拟，采用CALPHAD方法，对纳米层合板和SiC之间的相互扩散过程进行了评价。此外，可选的实施方式的CTE匹配，富铝夹层将根据这些计算，其中AlN是注定的，由于之间的CTE SiC和MAX或MAB相。最后，将进行不同纳米层压涂层TiAl和SiC衬底材料的长期循环氧化测试和在水蒸气气氛中的等温暴露。涂层和未涂层的TiAl合金的力学行为将通过高温环境下的拉伸、疲劳和蠕变试验进行评估。

Nanolaminate coatings based on MAX or MAB phases (where M is an early transition metal, A is an A-group element, X is carbon or nitrogen, and B is boron) combine unique ceramic and metallic material properties, providing significant potential for applications in high temperature environments. Within the project the manufacturing of the alumina forming MAX and MAB (with M = Cr or Ti and A = Al) nanolaminate coatings deposited by various PVD techniques will be validated and their performance at high temperature under dry and wet atmospheres will be elucidated. For the first time, three different PVD techniques available at the partnering institutions in Poland and Germany will be compared, including High Power Pulsed Magnetron Sputtering, DC and reactive magnetron sputtering and Closed Hollow Cathode PVD. The possibility to compare and combine these techniques enables a unique opportunity to understand the influence of various deposition parameters on the performance of the nanolaminate coatings. The coatings will be applied on intermetallic TiAl and ceramic SiC. The project will focus on the development of a protective thermally grown oxide layer composed of alumina and its evolution during long-term high temperature exposures. A promising lifetime improvement is expected for TiAl alloys due to stabilization of the alumina layer by the replenishing effect provided by the Al-rich substrate, thereby preventing the degradation of the MAX/MAB phase coatings due to Al-depletion by inward diffusion into the substrate material. Moreover, the well-known deterioration of the mechanical properties of TiAl by protective, but brittle coatings could be prevented by the deposition of ductile MAX or MAB phase based nanolaminates. In case of the silicon carbide, the necessity for protection against water vapor corrosion is mandatory. The state-of-the art environmental barrier coating systems are based on rare earth silicates with up to 4 different layers. For this reason, their potential replacement by single layered and alumina forming MAX or MAB phase-based coatings is evaluated, providing a sustainable raw material usage. Special attention will be paid to the adhesion of the nanolaminates during high temperature exposure as well as the interface design between coatings and the inert ceramic SiC. Interdiffusion processes between the nanolaminates and SiC will be evaluated by experiments and thermodynamic simulations using CALPHAD methods. Moreover, the optional implementation of a CTE-matched, Al-rich interlayer will be investigated based on these calculations, where AlN is predestined due to a CTE between SiC and MAX or MAB-phases. Finally, long-term cyclic oxidation tests and isothermal exposures in water vapor atmospheres of the different nanolaminate coated TiAl and SiC substrate materials will be performed. The mechanical behavior of the coated and uncoated TiAl alloy will be evaluated by tensile, fatigue and creep tests in high temperature environments.