Vacuum Plasma Processing for Aerospace Engine Applications

AMT AG (Dottingen, Switzerland) has developed low pressure, vacuum plasma, and hybrid processes for plasma spraying coatings of aerospace engine components.   Increasing demands on aerospace engine coating performance has necessitated further development and implementation of low pressure, and vacuum plasma processing.   The comparison of coatings produced in vacuum as compared to standard air plasma spray (APS) will be investigated.  System processes and configurations, and differences, between low pressure and vacuum plasma will be investigated.   These processes will be compared to air plasma spray processes (length of plume, presence of oxygen, etc.).

In contrast to standard atmospheric air plasma spray processes, vacuum processes consists stainless process chambers, high volume vacuum systems, load-locks, gun drives, work-piece manipulators (stings), and high power plasma spray systems.  Even within vacuum systems, considerable differences exist between batch and continuous processes and configurations.  Hybrid systems are also developed which consist of attributes of these latter two systems.  Process and configuration differences between these systems will be examined.

Nickel-based coatings will be produced with low pressure and vacuum plasma in comparison to APS.  The benefits of vacuum plasma processing will be discussed and compared to traditional air plasma spray coatings.  Microstructure and mechanical property evaluations will be conducted for coatings produced.  Microstructural analysis will be conducted evaluating coating buildup, oxides and porosity using optical and scanning electron microscopy.  Spray rates, production rates and other items of importance will also be discussed.