Elucidating Emerging Phenomena Associated with Deposit-Induced Corrosion at Elevated Temperatures
Abstract
The hot-section components of marine and aero turbine engines must endure harsh environments often in combination with some form ofmechanical loading. These factors contrive to limit component service life and/or performance. At present, there is no good correlation between the environmental properties of a given material and its durability in a modern engine. This lack of correlation imposes advancement limitations, including the development of an accurate physics- and chemistry-based cumulative damage model (CDM) for components. To be accurate, a CDM must consider environmental degradation together with component mechanical damage, e.g., creep and fatigue. While the latter is generally well understood owing to extensive past research, the same cannot be stated about environmental degradation resistance, particularly under complex (i.e., more realistic) conditions. Indeed, the weakest link in developing a full CDM is the lack of ability to accurately account for environmental degradation which may or not be associated with effects on mechanical properties. At the same time, any exacerbating role of mechanical load on environmental degradation of components must be understood. Deposit-induced corrosion of components is a particularly significant issue due to engine design advances that have increasseverity of deposit-induced corrosion can be linked to the SO2/SO3 content in the atmosphere, component thermal history, and the chemistry of the deposits. For instance, deposits found in degraded engines have been shown to contain Na, Ca, K, Mg, S, and O; however, the roles of complex deposit chemistry on corrosion and the associated potential impact of mechanical loading and properties are very poorly understood. Moreover, unforeseen modes of degradation are being observed. Adding to lack of understanding is the chemical complexity of turbine-engine alloys and coatings; a complexity that favors mechanical strength at the expense of environmental resistance. This proposed effort, in collaboration with both university and company partners, will significantly advance current testing, materials development and performance-prediction capabilities by a systematic approach that will achieve the following main research objectives: 1.Establishing a better understanding of actual engine conditions and the modes of component degradation that are most prevalent in current and advanced engines; 2.Further developing laboratory-scale testing procedures that better reflect component duty cycles in order to accurately duplicate the primary modes of degradation found in service;3.Elucidating the important reactions between atmospheric deposits and engine-component materials that are leading to emerging modes of attack; and4.Developing methodologies to incorporate this new understanding into both mitigation strategies and durabiosed initiative will be interactions with key engine OEMs that are relevant to NAVSEA and NAVAIR, i.e., GE, Rolls-Royce and Pratt &Whitney, and collaborative linkages with universities and Navy-supported STTR/SBIR projects. With input received from ONR (i.e., Dr. David Shifler), the industry and university collaborations will be with researchers who will provide expertise to this timely initiative. Such a dedicated project to effectively address corrosion-related issues relevant to advanced gas turbine operations is bothunprecedented and essential to engine durability advancements.This proposed initiative will have the further benefit of educating students and professionals in the area of high temperature corrosion, an area in which far too few scientists are being educated in the U.S.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jun 09, 2021
- Source ID
- N000142112596
Entities
People
- Brian T Gleeson
Organizations
- Office of Naval Research
- United States Navy
- University of Pittsburgh