Thin film sensor techniques for the instrumentation of ceramic/metal interfaces in next generation aero gas turbines

Shepherd, RS

Abstract

The growth of thrust and improved aeroengine efficiency has been gained by
increased temperatures throughout the engine. This has been achieved by improved
material technology and the continuous cooling of components complemented by the
addition of thermal barrier coatings (TBC) to turbine and combustion chamber
components. The aggressive nature of the application process of the TBC has
previously made the measurement of metal surface temperature and strain
exceedingly difficult on components to which it is applied.
In the present study magnetron sputter-deposited thin film sensor techniques have
been developed specifically for compressor and turbine applications of noble metal
thermocouples and strain gauges. The deposition, patterning and evaluation of
reactively sputtered aluminium oxide, type R platinum thermocouples as well as
PdCr and PtW dynamic strain gauges is reported. A sputtered NiCoCrAlY coating
has been developed to replace the vacuum plasma spray process currently used in the
TBC system. The most favourable location for the thin film sensor is at the
metal/ceramic interface of the TBC system. However, in order to protect the sensor
from the aggressive TBC process, the sensor has been deposited in a novel
installation between two layers of NiCoCrAlY bond coat. Several trials have been
performed to fabricate this package on turbine blade material substrates.
This work has demonstrated that the proposed sensor structure is feasible. However
there are problems with delamination due to contamination and residual stress and
with poor electrical insulation and these have limited the high temperature testing
that could be performed. The novel techniques developed are already being utilised
in measurement applications on components without TBCs. This work has been
performed in an industrial context. The extensive project and risk management
activities are reported.

Citation

Shepherd, R. Thin film sensor techniques for the instrumentation of ceramic/metal interfaces in next generation aero gas turbines. (Thesis). University of Salford

• Thesis Type: Thesis
• Deposit Date: Sep 19, 2011
• Publicly Available Date: Sep 19, 2011
• Award Date: Jan 1, 1999