Investigation of structural integrity and corrosion behaviour of thermal barrier coating

摘要

When aluminium alloys are exposed to different chemical environment at high temperature, corrosion is a life-limiting factor. In this investigation, nano composites of double layer CSZ and SiAlON thermal barrier coating were deposited on the aluminium alloy substrate using atmospheric plasma spraying technique. The anti-corrosion behaviour of the CSZ and SiAlON double layer coating as well as substrate were investigated in 3.5% NaCI solution and H_2SO_4 solution by potentiodynamic polarisation method. The results reveal that the coated sample shows highest corrosion resistant than the bare metal. To understand the degree of corrosion behaviour in coating, SEM analysis is carried out. On the other hand, the structural integrity and hardness of the surface of coatings were investigated by using scratch test. The scratched surfaces were inspected by SEM and phase analysis was carried by EDX and the results were characterised. The scratch test shows a better hardness resistance even at high load.