Nanocrystalline bond coat development

燃气涡轮发动机被认为是传统材料系统中最恶劣的操作环境之一。人们对发动机性能、热效率和部件耐久性的要求越来越高，这导致了热障涂层（TBC）系统的发展。这些系统通常用于燃气涡轮发动机的热部件，如叶片、叶片和燃烧室，以防止高温氧化和腐蚀。tbc通常由氧化钇-部分稳定的氧化锆面漆和MCrAlY（其中M可以是Ni和/或Co）结合涂层组成，通常通过热喷涂技术（如等离子体和/或HVOF喷涂）应用于要保护的高温合金母材上。由于过早失效，TBC系统的全部潜力尚未充分发挥，通常发生在粘结层-面涂层界面。最近的研究显示了获得增强TBC性能的有希望的解决方案。特别是利用HVOF制备了纳米晶键合层。虽然与原始的纳米晶原料粉末相比，这些结合层表现出部分晶粒生长，但它们表现出更好的氧化和腐蚀行为，从而提高了TBC性能。然而，这些研究表明，使用HVOF来生产结合涂层，由于不可避免的原料粉末在飞行中氧化，促进了有害氧化物的形成。在不产生有害氧化物和在喷涂过程中不生长晶粒的情况下生产纳米晶结合涂层是生产增强型TBC体系的解决方案。该研究项目的长期目标是通过首先使用CGDS和p-CGDS技术结合使用现有铣削技术生产纳米晶粉末来生产非氧化的纳米晶MCrAlY结合涂层，成功生产出具有更好分层/开裂性能的增强TBC系统（短期目标）。预计非氧化纳米晶结合层将在分层/开裂方面表现出优越的性能。

Gas turbine engines are considered to be amongst the most hostile operating environments for conventional material systems. Increasing demands for higher engine performance, thermal efficiency and durability of components have led to the development of thermal barrier coating (TBC) systems. These systems are typically used on the hot section components of gas turbine engines, such as blades, vanes and combustors for protection against high temperature oxidation and corrosion. TBCs typically consist of an yttria-partially-stabilized zirconia top coat and a MCrAlY (where M can be Ni and/or Co) bond coat usually applied by thermal spray techniques such as plasma and/or HVOF spraying on the superalloy base metal to be protected. The full potential of TBC systems is yet to be reached due to premature failure, usually occurring at the bond coat-top coat interface. Recent studies have shown promising solutions to obtain enhanced performance TBC. In particular, nanocrystalline bond coats have been produced by HVOF. Although these bond coats exhibited partial grain growth compared to the original nanocrystalline feedstock powder, they exhibited improved oxidation and corrosion behaviour, thus enhancing the TBC performances. However, these studies have revealed that the use of HVOF to produce the bond coat promotes the formation of detrimental oxides due to unavoidable in-flight oxidation of the feedstock powder. The production of nanocrystalline bond coat without the formation of harmful oxides and grain growth during spraying is sought as the solution to producing enhanced TBC systems. The long term objective of this research project is to successfully produce enhanced TBC systems that will exhibit better performances with respect to delamination/cracking, by first producing non-oxidized nanocrystalline MCrAlY bond coats using both CGDS and p-CGDS techniques combined with nanocrystalline powder production using existing milling techniques (shorter term objective).It is expected that non-oxidized nanocrystalline bond coats will exhibit superior performances with respect to delamination/cracking.