The origins of complex CMAS deposits in aircraft engines and their effects on engine degradation

这个博士项目将解决航空业面临的一个主要挑战，因为它努力提高能效，即吸入空气中的沙尘引起的发动机部件腐蚀。吸入的空气中的沙子和灰尘对飞机发动机来说是一个问题，因为它们会在发动机内部熔化，产生所谓的CMAS熔体，这些熔体会渗透并损坏旨在保护发动机部件的热障涂层，对部件寿命和发动机效率造成严重和昂贵的后果。发动机温度越高，熔化的情况就越多。现代燃气涡轮机发动机已经在非常高的温度下运行，以最大限度地提高燃油效率，未来的发动机可能会在更高的温度下运行，这意味着CMAS攻击将是一个更大的问题。此外，由于气候变化引起的荒漠化和沙尘暴等极端天气事件的增加，许多航空公司正在经历更多的沙尘吸入。因此，航空业大力推动技术开发，以最大限度地减少CMAS熔体形成的机会。除此之外，还需要更好地了解矿床形成的条件。该博士学位将为解决这一问题并最终减少航空的经济和环境影响做出重要贡献。该项目的目的是促进对CMAS矿床的起源和性质的理解，而不仅仅是其主要成分CaO，MgO，Al2O3和SiO2。将被研究的主要附加成分是硫，它与广泛的发动机损坏机制有关。硫有各种可能的来源，从摄入的矿物质到火山或人为的SO2气体。盐，NaCl，是飞机发动机内部高温下另一种高度反应性的物质。当这些不同的组分在发动机中相互作用时，产生复杂的CMAS沉积物的反应知之甚少，沉积物的性质，如熔化温度和粘度也知之甚少。这个问题将从两个方向着手：（i）高温试验，和（ii）在役发动机和整机试验的沉积物分析。实验将使用曼彻斯特大学实验岩石学实验室的高温炉。实验样品和发动机沉积物的分析将使用X射线衍射来确定矿物学，扫描电子显微镜来研究CMAS熔体与底层热障涂层相互作用时的纹理，以及拉曼光谱来研究矿物和玻璃的结构状态。

This PhD project will address a major challenge faced by the airline industry as it strives to become more energy-efficient, namely the corrosion of engine components caused by ingestion of airborne sand and dust. Ingested airborne sand and dust are a problem for aircraft engines because, among other effects, they can melt inside the engine to produce so-called CMAS melts that can infiltrate and damage the thermal barrier coatings that are designed to protect engine components, with serious and expensive consequences for component life and engine efficiency. The higher the engine temperature, the more melting will occur. Modern gas turbine engines already run at very high temperatures in order to maximise fuel efficiency, and the engines of the future are likely to run at even higher temperatures, meaning CMAS attack will be even more of a problem. Furthermore, many airlines are experiencing greater sand and dust ingestion as a result of climate change induced desertification and an increase in extreme weather events such as sand storms. There is therefore a major push within the airline industry to develop technologies to minimise the opportunities for CMAS melts to form. Alongside this is a need to better understand the conditions in which the deposits form. This PhD will provide an important contribution to addressing this problem and ultimately reducing the economic and environmental impacts of aviation. The aim of the project is to advance the understanding of the origins and properties of CMAS deposits beyond their main components of CaO, MgO, Al2O3 and SiO2. The main additional component that will be studied is sulfur, which is implicated in a wide range of engine damage mechanisms. There are various possible origins of the sulfur, from ingested minerals to volcanic or anthropogenic SO2 gas. Salt, NaCl, is another highly reactive species at the high temperatures inside aircraft engines. The reactions that produce the complex CMAS deposits which result when these different components interact in the engine are poorly understood, as are the properties of the deposits, such as melting temperature and viscosity. The problem will be approached from two directions: (i) high-temperature experiments, and (ii) analysis of deposits from in-service engines and from whole-engine tests. The experiments will use high-temperature furnaces in the Experimental Petrology laboratories at the University of Manchester. Analysis of experimental samples and engine deposits will use X-ray diffraction to determine mineralogy, scanning electron microscopy to investigate textures as the CMAS melts interact with the underlying thermal barrier coatings, and Raman spectroscopy to investigate the structural state of minerals and glasses.