Nanocrystalline bond coat development

燃气轮机发动机被认为是传统材料系统最恶劣的运行环境之一。对发动机性能、热效率和部件耐久性的日益增长的需求导致了热障涂层(TBC)系统的发展。这些系统通常用于燃气轮机发动机的热段部件，如叶片、叶片和燃烧室，以防止高温氧化和腐蚀。热障涂层通常由氧化钇部分稳定的氧化锆面涂层和MCrAlY(其中M可以是镍和/或钴)粘结涂层组成，通常通过热喷涂技术在要保护的高温合金母材上进行喷涂，例如等离子和/或超音速火焰喷涂。由于过早失效，TBC系统的全部潜力尚未达到，通常发生在粘合涂层-顶层界面。最近的研究表明，有希望的解决方案，以获得增强的性能TBC。特别是，超音速火焰喷涂技术已经生产出了纳米晶粘结涂层。虽然这些粘结涂层与原始的纳米晶原料粉末相比有部分晶粒长大，但它们的氧化和腐蚀性能有所改善，从而提高了热障涂层的性能。然而，这些研究表明，由于原料粉末不可避免地在飞行中氧化，使用超音速火焰来生产粘结剂涂层会促进有害氧化物的形成。寻求在喷涂过程中不生成有害氧化物和不生长颗粒的纳米晶粘结涂层作为生产增强型热障涂层系统的解决方案。这项研究项目的长期目标是通过首先使用CGDS和p-CGDS技术结合使用现有球磨技术生产纳米晶粉末来生产具有更好的分层/开裂性能的增强型TBC系统(短期目标)。

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.