Rain erosion characteristics of electrodeposited Ni–SiC metal-matrix composite layers

Fibre reinforced plastics (FRP) are finding greater use in aerospace applications. In order to improve the low intrinsic rain erosion resistance of these materials electrodeposited layers consisting of micrometer-sized SiC particles in a Ni matrix were examined. This study presents a microscopic examination of damage caused by water droplet impact at 225 m s−1, from which it was observed that the SiC particles were selectively removed from the surface of the matrix, causing a slight increase in the surface roughness that tended to a maximum value at 1000–2000 impacts of 2 mm diameter water droplets. The depth-dependent concentration of Si in the Ni matrix was estimated from energy-dispersive X-ray spectroscopy (EDX) measurements by varying the accelerating voltages of a range 5–25 kV and fitting the data using a Monte Carlo simulation method. A layer model was put forward that would account for the observed results, showing that SiC was selectively removed from the upper 0.4 μm of the deposit.