Journal of Material Sciences & Engineering

Microhardness and Adhesion Strength of PMC’s Coatings by NiCr Alloy

Abstract

Kareem AA and Raheem Z

The use of polymer matrix composites (PMCs) in the gas flow path of advanced turbine engines offers significant benefits for aircraft engine performance but their useful lifetime is limited by their poor environmental resistance. Flame sprayed NiCr graded coatings are being investigated as a method to address this technology gap by providing high temperature and environmental protection to polymer matrix composites. In this research coating was spread with two configuration, coating with bound coat and coating without bound coat. In general the coating with bound coat and coating without bound coat showed increase in micro hardness and adhesion with increase curing temperature; this is due to the microstructural changes the physical splat structure of the coating also changes with heat treatment. All coating failed at the interface between the composites and the coating, failure occurs along the weakest plane within the system, some of the coating systems that have presented fracture at the bond coat/top coat interface. The surface topography of NiCr films was further examined by using AFM atomic force microscopy as a function of curing temperature at 100,200 and 300°C for 1 h each, it can be clearly seen that the island structure was observed and the Rmax increase, the surface became rougher with increasing curing temperature. The surface morphology and microstructure of the coating were examined using SEM.